Drug Control in Australia: Where to Next?

Review

Abstract

Substance use and associated disorders are increasingly recognised as a global health issue. As attitudes towards drug use disorders evolve, varying drug control policies worldwide are called into question. Nations such as the United States of America utilise the criminal justice system to place sanctions on those contravening drug control policy, which often results in cycles of incarceration, further drug use, and poverty. In contrast, Portugal has revolutionised its approach to drug control since the turn of the century by decriminalising all drugs to great effect. In view of this wide spectrum of attitudes towards drug control, the future of Australia’s approach to drug control policy is examined. 

 

Introduction

The International Classification of Diseases defines substance use disorders as “continuing drug consumption despite severe adverse consequences”.[1] A report by the office of National Drug Control Policy in 2010 outlined the detriments of substance use disorders using a biopsychosocial paradigm (Figure 1).[1, 2]

Figure 1: The biopsychosocial adverse outcomes related to substance use disorders [1, 2]

Substance use disorders are managed through three main drug policy approaches: decriminalisation, criminalisation, and harm minimisation. Decriminalisation involves prohibiting and regulating drugs but excluding sanctions from criminal law jurisdiction, whereas criminalisation is the attribution of criminal offences to drug-related activities.[3, 4] Harm minimisation strives to decrease adverse consequences without aiming to reduce consumption.[1] Substance use disorders are perpetuated by social stigma and thus the political context is a key determinant of long-term health outcomes.[3]

Benefits and detriments of different policy approaches

Criminalisation of drugs, and the subsequent incarceration of drug users, provides the immediate benefit of removing the individual from an environment that exacerbates their drug use, and prevents the community from being threatened by drug-affected behaviour. Additionally, incarceration allows the government to demonstrate the work being done to tackle drugs in a manner that is tangible and easily understood by the general public. However, punitive drug law enforcement alone may fail to address or even worsen health complications of drug use. It can marginalise populations at risk of poorer health and increase barriers to seeking health services, as illustrated by the growing epidemic of HIV/AIDS and hepatitis C amongst injecting drug users.[5] Moreover, drug law enforcement has minimal impact on the drug market itself, although there is some evidence that it may alleviate a degree of associated harm.[1, 6]

Advantages of the harm minimisation approach include curbing the progression of the HIV/AIDs epidemic through safe needle programs and deterring criminal behaviours.[1, 7] This is achieved through demand and supply reduction, prevention campaigns, and improved access to treatment and harm reduction.[8] Critiques of this approach include maintaining demand for the illicit drug market, and ineffectively addressing all biopsychosocial facets of substance use disorders.[8]

The main benefit of decriminalisation is that it reframes drug use as a public health problem, which allows for reallocation of funds from drug-related criminal justice proceedings and the prison system to rehabilitation services focusing on long-term health outcomes.[3] This, coupled with a shift in criminal justice focus to high-level drug offenders, ultimately results in less drug use and better long-term health outcomes.[3] Decriminalisation addresses substance use disorders in a biopsychosocial context and identifies it as a key public health issue, both key steps in arresting the perpetuation of stigma which only serves to isolate drug users from health services.[3] Criticisms of decriminalisation include potential for increased accessibility to drugs and a cheaper street value, which could result in increased uptake of drug use.[9]

In 2009, Antonio Costa, the executive director of the United Nations Office on Drugs and Crime, affirmed that “drug use should be treated as an illness in need of medical help”, and appealed for universal access to drug treatment.[2] In 2011, the Global Commission on Drug Policy emphasised that it was time to “end the criminalization, marginalization and stigmatization of people who use drugs but who do no harm to others”.[1] The World Health Organization and the United Nations echoed this view in their joint statement published in June 2017, stating that to ignore such a call to “[review] and [repeal] punitive laws….[including] drug use or possession of drugs for personal use” would be to “[violate] the most fundamental human rights protected in international treaties and in national laws and constitutions”.[10] This strong stance against discrimination in health care settings reflects the global shift in attitudes towards drug policy, from incarceration to rehabilitation of drug offenders. 

Drug control approaches worldwide

Criminalisation: the United States

The United States (US) has a strong stance of criminalisation towards illicit drugs and has a low threshold to prosecute drug offenders.[3] Its prison population has increased by almost 800% since 1980, in marked disproportion to its population growth, with 47% of all inmates imprisoned for drug-related crimes, and many with drug use disorders.[3] In 2010 alone, US $80 billion was spent on continuing incarceration of inmates.[3] Drug users, possessors and traffickers are treated equally in this criminal system, with mandatory minimum prison sentences.[3]

Without adequate rehabilitation services or emphasis on drug use and use disorders as a public health issue, the high rates of recidivism are unsurprising, often resulting in a cycle of criminality, incarceration and poverty, with subsequent economic burden on the community.[3] This is an issue fuelled by media sensationalism, portraying

Where drug courts – legal committees which redirect non-violent drug offenders from incarceration to treatment – have been trialled in the US, they have proven to decrease crime rates (7-14%) and recidivism (up to 35%), and improving rehabilitation uptake, treatment outcomes and stability of the family unit.[2] Such models are estimated to reduce health care costs related to substance use disorders by US $4 for every US $1 spent.[2]

While marijuana is considered illicit under US federal law, states are able to make independent laws, which are only disregarded in cases concerning juveniles, cross-border trafficking, or organised crime.[9, 11] Presently, over half of American states have legalised medicinal marijuana, and eight have further allowed recreational use.[9] Given the relatively recent legalisation of marijuana, data on its impact on usage patterns is currently conflicting, and more time is required for reliable assessment.[9] Studies have indicated that diversion of black market marijuana from legalised to criminalised states is likely to decrease marijuana prices, although the degree and impact of this is uncertain.[12, 13] Notably, there are significant economic benefits associated with the legalisation of marijuana.[9] In Colorado, where recreational marijuana use is legal, marijuana tax and licensing fees have been implemented, together generating over US $70 million in the first year alone.[9] This revenue was subsequently funnelled into school construction and youth and substance use programs).[9]

Criminalisation: Central Asia

Central Asian countries, such as Tajikistan, Kazakhstan, and Uzbekistan, have adopted an increasingly stringent approach to drugs.[14] In the year following the September 11 attacks, these countries received US $187.5 million from the US government to improve border control, counter-terrorism measures and counter-narcotics initiatives.[14] Between 2004 and 2007, a strong criminal justice-based approach was further reinforced in Central Asia with funding from international agencies, other foreign governments and national budgets directed to legal action against drug use.[14]

Further, national campaigns in Central Asia often label drug users as evil, increasing the stigma and discrimination which perpetuates cycles of drug use.[15] Little or no rehabilitation or treatment is available for substance users, with such countries preferring a model of criminalisation and incarceration.[14] For example, opioid substitution treatment is prohibited in Tajikistan and Turkmenistan, minimally available in Uzbekistan and Kyrgyzstan, and non-existent in Kazakhstan.[14] The lack of treatment for drug users and increasing accessibility of opiates has resulted in a growing HIV epidemic in Central Asian prison systems with poor long-term health outcomes.[14]

Decriminalisation: Portugal

Prior to 2001, drug use was criminalised in Portugal, yet rates of heroin use and drug trafficking continued to increase.[3] Consequently, the Portuguese government drafted a law decriminalising all drugs purchased, possessed or consumed for personal use. This law also had a public health focus towards rehabilitating those with substance use disorders, and a punitive focus towards high-level drug trafficking. This involves a committee of two medically-trained persons and one legally-trained person, deciding first whether an offence is protected by this law, and then whether the offender is suffering from a drug use disorder.[3] This law only aimed to decriminalise low-level drug offences; strict laws remain against high-level offenders and drug traffickers who propagate this vicious cycle and endanger the general community.[16]

After this law was passed, Portugal reduced its burden on the criminal-justice system, allowing more funding allocation towards public health endeavours, including prevention campaigns, treatment, and facilities.[17] Treatment uptake consequently increased, resulting in decreasing rates of drug-associated illnesses.[4, 18] During the four years following decriminalisation in 2000 to 2006, there was a significant decrease in the incidence of new cases of HIV/AIDS amongst drug users in Portugal, from almost 1400 to 400 persons.[18] Decreased rates of new hepatitis B and C infections have also been evident, attributed to the improved treatment and rehabilitation programs afforded by decriminalisation.[17, 18] Moreover, absolute numbers of drug-related deaths by each prohibited substance decreased; the total number of drug-related deaths decreased from 400 in 1999 to 290 in 2006.[18]

Importantly, while some speculated that decriminalisation would lead to lower prices of drugs and subsequent higher rates of usage, the cost of drugs did not decrease.[19] In fact, the rates of cannabis and cocaine use after decriminalisation have been three times lower than before.[18] Further, data extrapolations have predicted lower lifetime prevalence rates of drug use for almost all drug categories post-decriminalisation.[18]

Decriminalisation: West Africa

West African countries must contend with both international drug cartels and the growing transit of illicit substances to Europe and North America. Consequently, local consumption of illicit substances has increased, especially among younger persons, with significant economic, health and social consequences.[20] While data is scarce, in 2008 it was estimated there were 1.8 million intravenous drug users in Sub-Saharan Africa, of whom 12% were thought to be living with HIV.[20, 21]

In 2014, the West Africa Commission on Drugs published a declaration specifically stating that “criminalisation of drug use worsens health and social problems, puts huge pressures on the criminal justice system and incites corruption”, and that “drug use must be regarded primarily as a public health problem”, mirroring the movements of Portugal.[20] Despite these recommendations, there is currently no evidence that any West African countries have been successful in implementing drug decriminalisation policies.

Drug policy in Australia and the way forward

In 1985, the Australian Government adopted an official national drug policy of harm minimisation.[1] In the 2002-03 financial year, the Australian Government allocated $3.2 billion to managing illicit drugs, 75% of which was spent on drug law enforcement, aiming to decrease drug and drug-related crime, and improve public health and safety.[1, 16] Despite this investment, a staggering 400 Australians die yearly from heroin overdose, and most areas have a demand for substitution products far out-weighing the supply, notwithstanding the costly co-payment.[1] The methadone substitution program and syringe exchange services available in Australia have made an impact, yet with a growing affected population and the root cause unaddressed, the need is largely unmet.[1] Harm minimisation still perpetuates discrimination and marginalisation of drug users, instead, decriminalisation can reduce stigma and is essential to better health outcomes.[3]

The Australia21 report, published in 2012, was effective in initiating a debate on drug reform. The report not only illustrated the harmful effects of criminalising possession and personal use on drug-dependent individuals in an Australian context, but also highlighted the potential health benefits of some currently illicit drugs.[1, 8] This report left Australians to decide which legal system would allow for better biopsychosocial health and economic stability for the community with respect to those consuming drugs – rehabilitation or incarceration.

Australia should act to follow countries like Portugal that have prospered from revolutionising drug policy with respect to low-level offences and reform to decriminalise all drugs. As supported by the Global Commission on Drug Policy, a move towards decriminalisation of low-level drug offenses in Australia would allow for decreased economic burden on the criminal justice system, reallocation of funds to drug rehabilitation programs, and a sharpened focus on the illegality of high-level drug trafficking offenses.[3] Viewing drug use as a public health problem is the key first step to reducing stigma and consequently improving access to treatment and long-term health outcomes.

Conclusion

Criminalisation marginalises those afflicted with drug use disorders, who are already burdened with significant health, social and economic disadvantage. Where there is demand, there is supply, and tackling drug use disorders with criminal law is simply too late to create a meaningful impact on the individual or society at large. Poverty breeds poverty; while incarceration may remove the immediate threat from society, it does nothing to address the root cause.

Substance use disorders are a medical condition and public health problem, not a moral choice. Epitomised by Portugal, decriminalisation of drugs and rehabilitation fortifies a community, not just immediately, but with long-term positive effects in the workforce and crime rates, spanning generations. Substance use disorders, therefore, need to be reframed from a criminal, punitive problem, to one befitting the biopsychosocial model of health. Fortunately, throughout the world this is increasingly becoming the case.

Raquel Maggacis

Raquel Maggacis is a final year medical student at the University of Queensland. She has a keen passion for public health endeavours and hopes to one day intertwine this with a career as a medical physician.

Acknowledgements

Sophie Lim, Vector Associate Editor 

Conflict of Interest

None declared

Correspondance

raquel.maggacis@uqconnect.edu.au 

References

  1. Wodak AD. The need and direction for drug law reform in Australia. The Medical Journal of Australia. 2012;197(6):312-3.
  2. Madras BK. Office of National Drug Control Policy: a scientist in drug policy in Washington, DC. Ann N Y Acad Sci. 2010;1187:370-402.
  3. Sapp CE. Rehabilitate or incarcerate? A comparative analysis of the United States’ sentencing laws on low-level drug offenders and Portugal’s decriminalization of low-level drug offenses. Cardozo Journal of International & Comparative Law. 2014;23(1):63-97.
  4. Félix S, Portugal P, Tavares A. Going after the Addiction, Not the Addicted: The Impact of Drug Decriminalization in Portugal. IDEAS Working Paper Series from RePEc. 2017.
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  7. Webster IW. Managing legal and medical complexities in caring for people with drug and alcohol problems: a call for change. Med J Aust. 2016;204(4):141-2.
  8. The prohibition of illicit drugs is killing and criminalising our children and we are all letting it happen. [press release]. Canberra2012.
  9. Homel PB, Rick. Marijuana legalisation in the United States: An Australian perspective. Canberra: Australian Institute of Criminology; 2017 June 2017.
  10. Joint United Nations statement on ending discrimination in health care settings [press release]. World Health Organisation2017.
  11. Adler J. Symposium Marijuana, Federal Power, and the States: Introduction. Case Western Reserve Law Review. 2015;65(3):505-12.
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  13. Hall W, Weier M. Assessing the public health impacts of legalizing recreational cannabis use in the USA. Clin Pharmacol Ther. 2015;97(6):607-15.
  14. Latypov A. Understanding post 9/11 drug control policy and politics in Central Asia. Int J Drug Policy. 2009;20(5):387-91.
  15. Wolfe D. Paradoxes in antiretroviral treatment for injecting drug users: access, adherence and structural barriers in Asia and the former Soviet Union. Int J Drug Policy. 2007;18(4):246-54.
  16. Willis K. Measuring the effectiveness of drug law enforcement. Trends and Issues in Crime and Criminal Justice. 2011;406(1):1-7.
  17. Hughes CE, Stevens A. What Can We Learn From The Portuguese Decriminalization of Illicit Drugs? British Journal of Criminology. 2010;50(6):999-1022.
  18. Greenwald G. Drug Decriminalization in Portugal: Lessons for Creating Fair and Successful Drug Policies. Washington, DC: Cato Institute; 2009.
  19. Felix S, Portugal P. Drug decriminalization and the price of illicit drugs. Int J Drug Policy. 2017;39:121-9.
  20. Drugs WACo. Not Just in Transit: Drugs, the State and Society in West Africa. West Africa Commission on Drugs; 2014.
  21. Mathers BMD, Louisa; Phillips, Benjamin; Wiessing, Lucas; Hickman, Matthew; Strathdee, Steffanie A; Wodak, Alex; Panda, Samiran; Tyndall, Mark; Toufik, Abdalla; Mattick, Richard P. Global epidemiology of injecting drug use and HIV among people who inject drugs: a systematic review. The Lancet. 2008;372(9651):1733-45.

 

Sugar tax – A Sweet Solution for Obesity?

Review

Abstract

Background

The rising prevalence of obesity and obesity-related illnesses parallels the increase in sugar consumption across the globe. To limit consumption of sugar and tackle obesity, the World Health Organization has recommended that member states implement a tax on sugar. Such a tax is envisioned to reduce sugar consumption at a societal level, generate stable revenue for governments, and drive product reformulation. However, at present there is insufficient evidence to suggest any beneficial effect of a sugar tax on the incidence and prevalence of obesity.

Aim

This review examines the effectiveness of a sugar tax as an obesity prevention strategy.

Methods

A qualitative review of modelling and observational studies investigating the link between sugar tax and obesity, and conducted over the past ten years, was carried out. 

Findings

Modelling studies suggest that a tax on high-sugar foods and beverages is likely to have beneficial effects on obesity as increased price of taxed items leads to reduced consumption. However, observational studies suggest little benefit of a sugar tax on actual obesity rates in a population. Taxes in combination with other policy and regulatory approaches, for example health food subsidies and education campaigns, might be more effective than a tax on its own.

Conclusion

A tax on sugar is likely to be a step in the right direction as it would raise public awareness of the negative health effects of excess sugar and de-normalise consumption of excess sugar.

 

Introduction

The obesity epidemic

Over the past few decades, overweight and obesity have risen to epidemic proportions all over the globe. In 2014, more than 1.9 billion adults were overweight and 600 million were obese.[1] In 2013, 42 million children under the age of five were either overweight or obese, and this is predicted to increase to 70 million by 2025.[2] The growing prevalence of childhood obesity is particularly alarming given that it is a predisposing factor for lifelong obesity.[3] Obesity, defined as having a body mass index (BMI) greater than or equal to 30, is a major risk factor for non-communicable diseases such as cardiovascular disease, diabetes, cancer, and mental illness.[4] Since non-communicable diseases were responsible for 68% of all deaths in 2012, [5] it is apparent that the health burden of obesity is high.

Obesity is a complex heterogenous disease that arises from an interplay between our genes and the environment we live in. Highly energy-dense diets combined with a lack of adequate physical activity leads to a positive caloric balance and hence weight gain in genetically susceptible individuals. Our diet and physical activity are increasingly shaped and driven by broader social, cultural, economic, and political landscapes that are often beyond individual control and awareness.[6] The modern obesogenic environment, which provides easy access to calorie-rich processed food and encourages sedentary lifestyle, is mismatched to human physiology that evolved to survive in an environment of food scarcity.[7] At a population level, obesity can be viewed as a manifestation of a global economic system that currently prioritises wealth creation over health creation.[8]

Obesity’s sweet tooth

In recent decades, the rising prevalence of obesity has closely paralleled the burgeoning consumption of sugar all over the world.[9] Sugar is recognised as one of the biggest risk factors for obesity,[10-15] and the leading source of sugar in the diet is sugar sweetened beverages (SSBs).[15] Therefore, the current review will focus on SSBs as a proxy for sugar and the discussion about policies aimed at limiting sugar intake (i.e. sugar taxes), will predominantly revolve around SSBs.

SSBs are non-alcoholic beverages with added sugar and include soft drinks, fruit drinks, sports drinks, energy drinks, iced tea and coffee, and lemonade. SSBs are becoming increasingly popular in low- and middle-income countries, with Latin America and Asia leading the world in consumption.[16] The worldwide impact of SSBs on the burden of adiposity-related cardiovascular disease, cancer, and diabetes is estimated at a total of 8.5 million (95% CI: 2.8 – 19.2) disability-adjusted life years (DALYs) [17].

Limiting the intake of free sugars to less than 10% of total daily energy consumption is strongly recommended by the World Health Organisation and the US Dietary Guidelines Advisory Committee.[18, 19] For every additional serving of SSB per day, the likelihood of a child becoming obese increases by 60% over the course of two years.[20] The energy obtained from SSBs is added to an individual’s total energy intake rather than displacing other sources of calories due to the poor satiating properties of sugar in liquid form.[21] The net increase in calorie consumption is likely to contribute to an increase in body mass. Given the high burden of obesity-related illnesses on healthcare systems [17] and the strong evidence linking excess consumption of SSBs to obesity in children and adults,[15, 22] a reduction in SSB consumption is warranted. A decrease in consumption is especially pertinent as the major SSB consumers are children, adolescents and poorly educated individuals from lower socio-economic strata of society who may be less aware of the harmful effects of added sugar.[10]

Sugar tax as an obesity prevention strategy?

Population health interventions aimed at curbing the consumption of excess sugar are pertinent to curtail the obesity epidemic. Price is one of the key factors influencing food purchasing behaviour. People tend to reduce consumption of unhealthy foods in response to increased prices of such products.[23] To discourage purchase of SSBs and address the growing burden of obesity, countries such as France, Mexico, the UK, and Hungary, and several jurisdictions in the USA, have implemented a tax on sugar.[10] Following implementation of a €0.11 per 1.5 L excise tax on SSBs, which translated to a 6% price increase, France saw a 6.7% decline in demand for cola in the first two years.[24] SSBs are a sensible target for a sugar tax as they have a high calorie density with no additional nutritional value [10, 25] and can be clearly defined for policy implementation.[2]

A number of assumptions underscore the success of an SSB tax [26]: first, the tax must be passed onto consumers, leading to an increase in cost; second, SSBs follow the law of demand; and finally, the tax leads to a significant net reduction in energy intake despite substitution by consumers, for example by increasing consumption of fruit juices with comparable caloric content.[27] While a tax on sugary drinks may not be the silver bullet for obesity on its own, it has the potential to slow the epidemic. For this reason, recommendations to implement diet-related taxes should be taken seriously.[28, 29]

The success of an SSB tax as an obesity prevention strategy remains controversial. The plethora of studies investigating the link between sugar taxation and obesity prevention demonstrate conflicting results. There is currently no consensus regarding the best approach to implement a sugar tax. Furthermore, existing meta-analyses on the topic show inconsistent findings and are unable to include many primary studies in their analysis owing to methodological inconsistencies.

 Methods

Electronic databases (PubMed and Web of Science) were searched for relevant journal articles between 1 January 2007 and 1 July 2017. The year 2007 was chosen to ensure included studies were relevant to modern dietary habits and practices.

The following search strategy was used: (tax* OR price* OR economic* OR financial*) AND (sugar OR sweetened OR beverage* OR drink*) AND (intake OR consumption OR demand OR sale* OR diet OR weight OR overweight OR obes* OR body mass index OR BMI).

Searches were limited to articles published in English. Relevant articles were also identified by searching the reference lists of included studies. Abstracts were assessed for suitability of inclusion. Studies that were found to be suitable were read in full and their salient features reported here.

Economic feasibility of a sugar tax

Consumers do not bear the full costs of their decisions when it comes to high-calorie foods and beverages.[30] It is estimated that an individual with a BMI between 30 and 35 will accumulate 30% higher medical costs than a normal weight individual;[31] this increases to 50% in individuals with a BMI greater than 35.[32] In Canada, obesity-related healthcare costs are close to $6 billion [33] whereas in Australia this figure is close to $10.7 billion.[34] In addition to direct healthcare costs, there are indirect costs to the community associated with absenteeism and obesity-related premature death.[35]

A number of modelling studies have reported substantial healthcare cost savings and stable revenue streams from a tax on sugar.[14, 36-38] For example, annual healthcare cost savings of $23.6 billion (95% CI: 9.33 – 54.9) and annual revenue of $12.5 billion (95% CI: 8.92 – 14.1) have been predicted for a tax of $0.01 per ounce of sugar in the United States (US).[39] Importantly, a sugar tax combined with a fruit and vegetable subsidy is deemed to be poverty neutral,[37] an important consideration given the significantly higher relative cost of fresh produce,[40] especially in rural and remote communities. The revenue generated from an SSB tax can be used to cover the healthcare costs of obesity, support subsidies on healthy food options, and fund public and school education campaigns promoting childhood nutrition and obesity prevention.

Effectiveness of a sugar tax for preventing obesity

Of various taxes on “unhealthy” foods, a tax on sugar was modelled to have the biggest health gain in the Australian population, equating to 270,000 DALYs (95% CI: 250,000 – 290,000) averted.[37] The effect of a sugar tax on BMI was found to be modest, equating to a BMI reduction of 0.1 in males and 0.06 in females, and a decline in obesity prevalence of 2.7% in males and 1.2% in females [36]. In a study modelling the German population, a 20% SSB tax was shown to reduce the prevalence of obesity by 4% in males aged 20 to 29.[41] Similarly, a modelling study by Cancer Research UK estimated that a 20% tax on SSBs could prevent 3.7 million people from becoming obese by 2025. Significant, albeit small, inverse associations between SSB taxes and weight gain have been reported by other modelling studies.[15] These could represent important changes over time and alter the prevalence of obesity at a population level.[42] Importantly, reductions in energy consumption were more pronounced in low- and middle-income groups.[38, 41, 43]

One of the biggest limitations of these studies is that they are population models.[37] They rely on national data which may be outdated and assume a linear relationship between weight changes and energy consumption without accounting for substitution behaviour by consumers and often relies on self-reported data.[41] The substitution effect is an obvious confounder in studies that do not classify fruit juices as SSBs, despite juices often containing more sugar than soft drinks.[14] Another limitation of modelling studies is the lack of information on long-term SSB price elasticity that is specific to geographic and economic subgroups.[14]

Six months after implementation of an SSB excise tax ($0.01 per ounce), consumption of SSBs decreased in Berkeley, California (–21%) and increased in comparable neighbouring cities that did not levy a sugar tax (+4%). Of the 124 people who reported changing drinking habits as a result of the tax, 82% reported drinking SSBs less frequently and 40% reported drinking smaller sizes because of the tax.[44] Similarly, following introduction of an SSB tax (1 peso/litre) by the Mexican government, the purchase of SSBs declined by an average of 6% during the first year of the tax and this decline was greater in low income groups.[45] The average Mexican purchased 4.2 litres less taxed beverages than expected during the first year, however, purchase of untaxed beverages increased by 13 litres on average.[45] Whether the increased consumption of untaxed beverages compensated for the reduced caloric intake due to the decline in taxed beverages was unable to be determined, so the effect of the sugar tax on net caloric intake remains to be seen. Given their short time frame, these observational studies provide no indication of the effect of a sugar tax on actual obesity rates in a population.

Similarly, surveys investigating consumers’ purchasing behaviour may not necessarily predict their actual purchasing habits.[46] This is critical in light of the fact that a 20% tax on SSBs did not result in an appreciable reduction in consumers’ likelihood to buy SSBs, despite their perception that they were more expensive.[46] Notwithstanding these pitfalls, a review of cross-sectional and longitudinal studies investigating the impact of sugar taxes on weight gain found several studies that demonstrated an inverse association between price increase of SSBs and point prevalence of overweight and obesity.[13] However, the magnitude of change reported in these studies was small.[13]

Outlook

Reduced consumption of sugar by virtue of an SSB tax may not necessarily translate to decreased body weight, particularly if unhealthy alternatives still exist. A tax on SSBs will only be effective in reducing obesity when there is no substitution with another untaxed high-calorie food or beverage.[47] A tax on sugar-rich foods (e.g. confectionary) in conjunction with a tax on SSBs would reduce the likelihood of substitution and therefore increase the effectiveness of the public health intervention. Taxes on high-fat foods will need to be considered in the future as adjuncts to the sugar tax. Given the complexity of taxing foods high in sugar and fat, and limited research on their effectiveness, this requires further study.

In addition to reducing calorie intake through a sugar tax, other aspects of the obesogenic environment that require monitoring and regulation include food labelling, food portions, food advertisements, and plain packaging. A sugar tax on its own is unlikely to be the panacea for obesity prevention. It is widely accepted that taxes have the potential to reduce sugar consumption, drive production reformulation, and generate substantial revenue for governments.[16] While it appears plausible that reduced sugar consumption and product reformulation would be beneficial to tackle obesity, whether this is actually the case remains to be seen. To address the obesity epidemic, a number of other population level policy measures, including advertising restriction, reformulation targets, health star rating systems, promotion of healthy transport choices, and sustained high-impact education campaigns are warranted.[48]

While the effect of sugar taxes on SSB consumption and obesity have been carried out in some low- and middle-income groups,[38, 41, 43] there is a paucity of literature from developing nations on the impact of decreasing SSB consumption on obesity rates. This is pertinent given that low- and middle-income nations are disproportionately impacted by obesity and related non-communicable diseases.

Conclusion

Obesity and obesity-related diseases are a significant burden on healthcare systems around the world. The global prevalence of obesity has increased and excess consumption of sugar, in particular SSBs, is one of the strongest drivers of that increase. To curb the obesity epidemic, a number of countries have adopted various forms of sugar taxes. While theoretically and economically sound, a sugar tax on its own might be insufficient to curb the obesity epidemic. However, a tax on sugar is likely to be a step in the right direction as it would raise public awareness of the adverse health effects of excess sugar and de-normalise excess consumption. A tax on SSBs can also encourage industry to reformulate its products with lower sugar levels. Taxes in combination with other policy and regulatory approaches, for example subsidies to healthy foods, graphic warning labels, and awareness campaigns, might be more effective to curb the obesity epidemic than a tax on its own. A sustained, focussed, and multi-pronged public health intervention worked in the past against Big Tobacco. There is no reason to believe that similar perseverance will not work against Big Sugar.

Saiuj Bhat

Saiuj is a first year medical student at the University of Western Australia with a passion for understanding the social and commercial determinants of health. He also has an interest in tissue engineering, in particular organoid technology, and the promising that holds for many aspects of medicine in the future. He graduated last year with Honours in pharmacology.

Conflicts of interest

None declared

Correspondance

saiujbhat59@hotmail.com

References

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Dengue in the Pacific Islands

Review

Abstract

Without a fully effective vaccine, prophylactic measures, or sufficient treatment options, dengue has emerged as a significant global health threat. The Pacific Islands are particularly susceptible to dengue as they provide favourable conditions for the Aedes mosquito population, the vector responsible for spreading the virus. Strong public health protocols with an emphasis on vector control are considered to be the best way to combat dengue in this region. However, for a variety of social, economic, environmental and political factors, vector surveillance and control mechanisms are failing. This review seeks to provide an overview on the emergence of dengue in the Pacific Islands, why this region is susceptible due to virus and vector factors, and what has been done and can be done in the future to contain the dengue threat in this region.

 

Introduction

Dengue virus is a vector-borne disease primarily spread by the Aedes mosquito population; it is one of the most significant infectious diseases that remains without definitive prevention or treatment options. Due to a variety of environmental and social factors, the Pacific Islands are particularly susceptible to dengue and other arbovirus.[1, 2] This has significant associated morbidity, mortality and economic cost, particularly when patients contract ‘severe dengue’.[1-3] A diagnosis of dengue can be based on clinical signs and/or laboratory diagnosis, whilst a diagnosis of ‘severe dengue’ is based on serious complications including plasma leakage, severe haemorrhage or severe organ impairment.[3] These clinical manifestations and complications of dengue can cause severe illness, particularly in susceptible patient groups including children.[3]

Treatment options are limited particularly in resource poor settings, and thus preventing dengue and recognising outbreaks is critical.[3] Dengvaxia, a world-first dengue vaccine, has recently been approved for use in endemic settings, with the World Health Organization recommending high-risk nations implement it as part of their vaccination program.[4-6] However, the vaccine has variable levels of efficacy, and is not yet considered a cost-effective solution.[5, 6] Whilst dengue remains a growing threat, the Pacific Island region must urgently develop alternative cost-effective diagnostic, detection, treatment and prevention strategies.[4, 7, 8]

Methods

The intended focus of this literature review was dengue in the Pacific Island region. An Ovid MEDLINE search was conducted combining the search terms “Dengue”, “Aedes” and “Pacific”. Grey literature and data was also sourced from the World Health Organization (WHO) and other non-profit organisations. Additional resources were identified through analysing the articles retrieved through these searches.

Epidemiology

Prevalence

Dengue has been reported in several Pacific Island nations since the 1950s, but in the past decade the incidence has grown exponentially.[1, 9] Whilst in 2000 there was only 50 reported cases per 1000 people, by 2012 this had grown to 350 per 1000.[1] It is difficult to determine reliable data on the endemic levels of dengue in the Pacific Islands, as this depends on accurate and timely reporting to the Pacific Public Health Surveillance Network, still under development.[2] However, whilst dengue is not endemic in all Pacific Islands, it is emerging in previously untouched islands including the Solomon Islands and Papua New Guinea.[9] From 2016 to 2017 alone, there has been an unusual increase in dengue illness reported in the Solomon Islands, Vanuatu, Fiji and Palau.[10] With this growth, some reports indicate that the vast majority of the Pacific Island population will be infected at some point in their lives.[1] In Samoa, one study showed 96% of the population tested positive for IgG antibodies, indicating prior infection.[11] With 89% of 18-25 year olds testing positive, this demonstrated that most Samoans first contracted dengue during childhood, when dengue illness is more likely to be fatal.[7, 11]

Outbreaks

Dengue typically follows an epidemic pattern with 1 of the 4 serotypes causing outbreaks across the Pacific every three to five years. However, the number of outbreaks of concurrent serotypes has been growing.[2] After an outbreak of a single serotype, this strain of the virus tends to circulate throughout the region until the next outbreak of a different strain occurs.[12] A single outbreak can affect a large portion of the population, with the 2009 outbreaks affecting 14 Pacific nations.[13] During such outbreaks, complications increase, placing a burden on hospital resources, with 4% of the Federated States of Micronesia’s population requiring hospitalisation during the Kosrae state outbreak.[14] The frequency of outbreaks appears to be increasing,[4] though this may be due to improved surveillance.

The virus

Dengue virus (DENV) is a single-stranded, positive-sense RNA virus of the Flavivirus genus.[15] There are four serotypes DENV-1 to DENV-4. Though they only share 65% of their genomes, their clinical syndromes are nearly identical, and they all occupy the same ecological niche.[16, 17] Dengue epidemics usually result from introduction of a single serotype from hyper-endemic countries, which will remain dominant in the region for several years.[12,18,19] However, in 2012, outbreaks of all four DENV serotypes were noted in a single year [20]. Each DENV serotype has caused outbreaks or been prevalent in the Pacific Islands at various times (Table 1).

Table 1: Dengue Serotypes and Epidemiology

DENV Serotype Notable related epidemiology and outbreaks
DENV-1 The most prominent serotype in 2012-2013, causing the largest-ever documented outbreak affecting New Caledonia.[21]
DENV-2 Caused recent outbreaks in Tuvalu and a current outbreak in Samoa.[10, 22]
DENV-3 After 18 years of absence, has recently become the dominant serotype in the Pacific islands causing five ongoing outbreaks [23].
DENV-4 Caused one outbreak since 2012, is rare in the Pacific Islands [10].

 

Repeated infection of DENV of the same serotype is associated with increase risk of progressing to severe dengue, which is associated with higher morbidity and mortality if left untreated.[24] Those living in endemic areas such as the Pacific Islands are at an increased risk of being reinfected and thus complications are more common.

The Vector

Dengue, zika, chikungunya and other arboviruses are transmitted to humans through the bites of infected Aedes mosquitoes.[25] Aedes aegypti is the primary vector in the Pacific Islands and is widespread across the region except for Futuna and other isolated islands.[26,27] Aedes aegypti is associated with human migration and urbanisation, enabling it to be dominant in the region, however, Aedes albopictus, Aedes polynesiensis and nine other potential vectors have also been identified in the Pacific Islands.[27, 28]

Aedes mosquitoes begin their transmission cycle upon acquiring the dengue virus from the blood of a viraemic person; the virus then replicates in mosquito midgut epithelium before shedding its progeny into the haemocoel, which then disseminates into secondary target tissues such as salivary glands.[29] During the next feeding event, the mosquito transmits the virus to the host through saliva.[29,30] Aedes aegypti is capable of repeatedly transmitting the virus through this process irrespective of its number of hosts.[30]

The introduction of Aedes aegypti into different islands has been spurred by human migration; there have been intense population migrations in the Pacific Islands since European colonization.[31] Though the first dengue epidemic in the Pacific Islands was reported in the 1880s, descriptions of Aedes aegypti didn’t emerge until the 1960s in Fiji and Tonga.[20, 32, 33] Aedes aegypti then spread during World War II, when travel between the Pacific Islands and Asia, Europe, and America became more frequent.[34] Recent studies have now identified genetic variability in nine locations across Fiji, New Caledonia, Tonga and French Polynesia, suggesting a link between human migration and Aedes aegypti populations, possibly related to island isolation and environmental conditions.[25]

Several factors influence the transmission of DENV from mosquitoes to humans, including climate.[30] Higher temperatures enable the virus to replicate in higher concentrations, enhancing the vectors’ risk for pathogen transmission and contributing to the high prevalence of dengue infection in the tropical Pacific Islands[30] Globally, climate-induced variations in modelled Aedes aegypti populations were strongly correlated to historical dengue cases between 1958 to 1995.[35] Recent research from New Caledonia, where dengue spread by Aedes aegypti is a major public health problem, showed that the epidemic dynamics of dengue were predominantly driven by climate in the last forty years.[36] Another study found a positive correlation between dengue infection and El Nino southern oscillation in ten countries, with evidence of infection spreading from larger islands to smaller surrounding islands.[37] It is predicted that global warming will increase the latitudinal and altitudinal distribution of Aedes aegypti and subsequently DENV.[38,39]

Dengue Surveillance Methods

Dengue surveillance and tracking is essential to enable timely epidemic responses.[8] Though representatives from the Pacific Islands believe there is adequate surveillance infrastructure and systems, governments have not emphasised prevention. These systems must be strengthened to more accurately track dengue epidemiological data [8, 40]. Given financial difficulties, this may be better accomplished through alternative mechanisms.

One such alternative is the transport of serum and blood samples internationally.[41] When a new serotype emerges in one Pacific country, this is often followed by outbreaks in neighbouring countries [42]; using blood samples to identify emerging serotypes enables surveillance of viral spread across the region. Filter paper (FP)-dried blood spots have minimal health risk and so are not bound by dangerous goods regulations present in several Pacific nations [43]. Blood spiked with cultured DENV can be blotted on FP-cards and the serotype determined using reverse-transcriptase polymerase chain reaction.[44]. The serotype and genotype of DENV can be identified using FP-dried serum even after being transported over thousands of kilometres at tropical temperatures.[41] This method of surveillance particularly useful in the Pacific Islands, where samples may need to be transported over long distances.

Another method to monitor dengue levels is the use of international travellers as ‘sentinels’, so that the risk of dengue infection can be estimated through proxies who travelled to particular areas.[45] Patterns of local dengue incidence in the Pacific Islands were shown to be closely correlated with patterns of dengue incidence imported from the Pacific to New Zealand.[46] However, this method is more commonly retrospective and cannot provide an indication of outbreaks. A combination of both methods could be implemented to cheaply and effectively improve dengue surveillance in the regions.

Dengue Prevention and Control, Now and in the Future

Strategies and Policies

Many nations have been attempting to meet the WHO infectious disease strategy objectives (Figure 1) by implementing policies that address vector surveillance, health education for vector control and dengue prevention, and emergency response capacity.[8] However, an urgent policy review to combat dengue is needed, with a focus on emphasising dengue in climate change and environmental medicine policies.[48] It is also essential that dengue is classed as a notifiable disease across all Pacific Islands through legislation.[48]

Figure 1: Outline of the World Health Organization Infectious Disease Strategy [47]

A Dengue Vaccine

Although several live-attenuated dengue vaccines are undergoing phase III clinical trials, currently Dengvaxia (CYD-TDV) is the only vaccine that is licensed and registered for use in individuals aged 9-45 years and living in dengue endemic areas.[40] Modelling has shown that Dengvaxia would only have the highest net benefit and be most cost-effective if the majority of the population is vaccinated in dengue-endemic nations.[52] The WHO has recommended that nations with a high burden of disease, defined as seroprevalence >70% in 9 year-olds, introduce the vaccine.[4, 1] However, many nations worldwide are still debating this, and Dengvaxia is not currently licensed for use in Pacific Island nations.[5, 51]

From the two major phase III clinical trials for Dengvaxia, overall vaccine efficacy against severe dengue was 79%, however, this varied by serotype, age at vaccination, and previous dengue infection.[52] For those with a previous dengue infection, vaccination efficacy was 78%, however, it was only 38% for those with no prior infection.[52] In fact, a study has shown that Dengvaxia can also increase the risk of hospitalisation when seronegative individuals are vaccinated and later experience natural secondary dengue infection.[51] The pooled efficacy for those older than 9 years old was higher than those under 9 years of age, who have a higher risk of severe dengue (66% vs 44%).[3, 52] Finally, in terms of serotype, vaccine efficacy was shown to be higher against serotypes 3 (72%) and 4 (77%) than for serotypes 1 (55%) and 2 (43%).[52]

Further study is ongoing to determine whether dengue illness and hospitalisation has reduced in nations that have implemented Dengvaxia.[53, 54] However, with varying efficacy, and questions regarding long-term safety and cost-effectiveness, it is predicted that vaccination will only be possible in the Pacific Islands if it is priced competitively.[53, 54] Thus, for the time being, vector control will remain the focus of dengue control strategy in the Pacific Islands, with the aim of integrating vaccination once it is more efficacious and cost-effective.[55] At present, it is far more affordable and effective to combat dengue by improving vector control mechanisms, and vaccination will be most useful as an adjunct if appropriate for specific nations.

Vector Control: Currently Used Methods

Vector control currently offers the best option for preventing dengue, but delivery of prevention programmes in the Pacific Islands is often inefficient, ineffective or both.[7] Several mechanisms exist in various Pacific Islands to control outbreaks once they occur, however some of the most common efforts, such as pesticide spraying, have limited effectiveness.[56]

Factors that increase the risk of dengue transmission have included poor household drainage and hygiene problems, issues that can be addressed by health education programs to build a ‘prevention attitude’ among Pacific residents.[57, 58] However, it is believed that improving health education, awareness campaigns and technical support is necessary to ensure successful vector control.[8] Environmental factors such as buckets of stagnant water, allowing mosquitoes to breed, and host larvae and pupae, are other key risk factor which could be targeted through education campaigns.[59] Chemical treatment of breeding sites, insecticide spraying and biological control by introducing predators are mechanisms already utilised by some Pacific Islands which could be further implemented for vector control in the future.[60]

Vector Control: Innovative Approaches

Novel vector-based approaches aimed at controlling dengue include the use of obligate intracellular bacterium Wolbachia pipientis,[61] which interferes with reproduction in over 40% of insect species.[62] Although Wolbachia does not occur naturally in Aedes aegypti species, transinfection has been shown to be successful.[63] Recent studies in Cairns, Australia have shown stable transinfection of natural A. aegypti populations with the wMel strain of Wolbachia, rising to near-fixation within a matter of months and remaining established in those field sites unaided.[64] The antiviral activity of wMel has shown to be highly effective in laboratory studies even one year after field release.[65] The evidence supports the long-term stability of Wolbachia against the dengue virus, however, the effects on reduction of human disease in dengue-endemic regions is yet to be established, this is currently under investigation in Indonesia and Vietnam.[61]

Another promising vector control method is the sterile insect technique (SIT), which has historically been successful against a multitude of agricultural pests.[66] In the 1960s, large-scale SIT programs enabled the elimination of A. aegypti from 23 American countries.[67] SIT has recently re-emerged as a vector control strategy due to innovative technological advances including genetic modification of mosquitoes.[68] Using SIT, Cuba has come close to the eradication of A. aegypti [69] and Singapore has kept levels of the mosquitoes down for more than 30 years.[70] Though neither of these methods is currently used widely in Pacific Islands, these innovative strategies are potential cost-effective vector reduction methods.

Emergency Response Capacity

There is a significant need to grow emergency-response and outbreak-response to combat dengue.[8] Currently, the WHO and Red Cross manage the majority of outbreak control, both logistically and financially[14, 71] The Pacific Public Health Surveillance Network has provided some support in capacity building, and multiagency response teams have successfully been implemented during some outbreaks, but there remains a need to engage Pacific Directors and Ministers of Health to help prepare these multidisciplinary response teams for future outbreaks.[2, 14]

Conclusion

Dengue remains a significant threat in the Pacific Islands, with prevalence levels and the number of outbreaks continuing to increase. Until Dengvaxia or another dengue vaccine has a proven cost-effective public health benefit beyond the currently calculated values, it is unlikely to be deployed in Pacific Islands.[5, 51] The best hope for containing dengue is by improving region-wide surveillance and cost-effective, sustainable vector control mechanisms [6-8]. This requires Pacific Island governments to integrate dengue prevention into their environmental and public health policy, and work to improve vector surveillance and control methods, which may involve implementing innovative approaches [8, 48]. Another area that requires significant improvement is outbreak response, and upskilling all Pacific doctors to appropriately respond to dengue outbreaks [8, 60]. Ultimately, until the objectives outlined by the WHO are addressed, dengue will remain a growing challenge in the Pacific Islands.[7, 47] These islands must engage with the growing body of organisations working in the region to develop new and innovative surveillance and control approaches and combat dengue in the future.[7]

Madeleine Marsland and Dunya Tomic

Madeleine is a fourth year medical student who is interested in global health and research. She combines these interests in her role as Chief of Editorials and Publications for the Pacific Medical Students’ Association, and is also undertaking research with the Department of Anatomy and Developmental Biology at Monash University. She hopes to pursue global health research and policy.

Dunya is a fourth year medical student at Monash University with a particular interest in clinical research and medical ethics. She hopes to one day combine this with a career as a physician.

Conflicts of interest

None declared

Correspondance

dtom4@student.monash.edu

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