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Eradicating global infectious disease: Two steps forward and one step back?

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By: Jessica Hostetler, PhD

Source: CDC

The world made some good progress recently toward controlling or eliminating several diseases. Such gains are often long and hard fought. Vaccines are often a primary tool for eliminating diseases, which makes the rise in vaccine scepticism in many developed nations all the more troubling and fears of disease resurgences and outbreaks all too real.

The good news for disease control started in July with the commendation from the World Health Organization (WHO) to India for its work in eliminating yaws earlier in May of 2016. Yaws, often described as a “forgotten disease,” is a chronic skin disease caused by the bacterium Treponema pallidum, which is closely related to the organism that causes syphilis. It affects primarily children in poverty-stricken, crowded communities in about 13 countries with limited access to clean water, sanitation, and healthcare and can lead to severe disfigurement if not treated. Yaws is treated by a single dose of oral (Azithromycin) or injected (Benzathine penicillin) antibiotic. India tackled yaws through a campaign spanning years. “Highly targeted awareness and early treatment campaigns in vulnerable communities enabled treatment of yaws cases and interruption of disease transmission,” said Dr. Khetrapal Singh, the WHO Regional Director for South-East Asia in a WHO July press release. The success in India as the first country to eliminate yaws under the 2012 WHO neglected tropical diseases (NTD) roadmap gives renewed momentum toward global eradication in the remaining yaws-endemic countries by 2020.

More good news followed on September 5th with the announcement from WHO that Sri Lanka is now free of malaria. It is a large turnaround from the historical burden of the disease which was as high as 5 million cases per year in the 1930’s followed by a highly successful elimination program resulting in only 17 recorded cases in 1963. However, due to multiple factors, potentially including “human migrations, asymptomatic parasite-carriers, vector-reintroduction, behavioural changes in the vector and the emergence of drug and insecticide resistance,” cases soared again to half a million or more cases per year in the 1970s and 1980s. With a renewed focus on global malaria elimination in the 2000s, Sri Lanka has become a remarkable success story. As laid out in the WHO September press release, Sri Lanka’s strategy for elimination included targeting the parasites and the mosquitoes transmitting them through “mobile malaria clinics in high transmission areas” to give “prompt and effective treatment,” which reduced disease transmission and the parasite reservoir. Work such as this requires large teams of people for “effective surveillance, community engagement and health education.” But given Sri Lanka’s proximity to India, where malaria is still endemic, active surveillance for newly introduced cases will be essential to keep the disease at bay.

On September 27th, 2016, the Pan American Health Organization (PAHO) certified that the region of the Americas is free from endemic measles. This news isn’t strictly “new” as the last locally transmitted case of measles in the Americas occurred in Venezuela in 2002. Certification as being disease-free is a long process, however, and the Americas continued to experience over 5000 imported measles cases between 2003 and 2014, necessitating careful documentation to ensure local transmission had ended. Measles is a highly contagious virus and causes fever and a characteristic rash. It can lead to severe symptoms including “pneumonia, brain swelling and even death.” This is a historical success, but the WHO reports that measles still caused over 100,000 deaths globally, mostly children, in 2014. Continued vigilance and worldwide vaccination compliance are needed to maintain gains and reduce the disease where it still spreads endemically.

Such good news represents decades of hard work from international organizations, national governments and NGOs and many field workers on the ground. These efforts represent the best of humanity in working to alleviate suffering and eradicate disease. One of the primary tools in the fight against infectious diseases remains the development and mass administration of vaccines. In the US, vaccination skepticism has been growing for years on the heels of a now-retracted study in The Lancet in 1998 that proposed a link between the Measles-Mumps-Rubella (MMR) vaccine and the development of autism. While there is no evidence that vaccinations or vaccine ingredients cause autism in any way, the paper caused lasting damage to the public perception of vaccinations. A recent study examining American Academy of Pediatrics Periodic Surveys from 2006 and 2013 reports that while most parents no longer cite autism as a reason for avoiding vaccines for their children, many are now avoiding vaccinations because they are “unnecessary.” An increasing number of pediatricians (up from 6% in 2006 to 11% in 2013) report always dismissing patients for “continued vaccine refusal” citing both a lack of trust in the physician-patient relationship and concern for other patients as primary reasons. Non-compliance with vaccinations is largely viewed as the driver behind an outbreak of measles in and around the Disneyland resort in California in 2014-2015 as 67% of those with infections (who were vaccine eligible) “were intentionally unvaccinated because of personal beliefs.” Vaccination rates in some California communities had fallen below the level required for protection of the population; this spurred a controversial tightening of regulations requiring vaccinations for all public-school educated children with no exemption for religious or personal beliefs.

The international news is even more concerning with a recent global survey (with a commentary in Science) looking at attitudes toward vaccination showing that 41% of respondents from France and 31% of respondents from Japan disagreed with the statement that vaccines are safe. Russia had the highest scepticism about the importance of vaccines at 17%. The survey notes that “Countries with high levels of schooling and good access to health services are associated with lower rates of positive sentiment, pointing to an emerging inverse relationship between vaccine sentiments and socio-economic status.” The WHO reports that vaccines prevent 2-3 million deaths per year from diphtheria, tetanus, pertussis (whooping cough), and measles, but that as many as 1.5 million children under the age of 5 died from vaccine-preventable diseases in 2008. Vaccine-scepticism and outbreaks from vaccine non-compliance represent an alarming and avoidable threat as we aim to eliminate vaccine-preventable diseases from the world. As a perspective by Dr. Douglas S. Diekema in the New England Journal of Medicine notes, we must set a high goal in the US and globally to improve childhood vaccination rates through increased and free access to vaccines, but also swift rebuttals of unbalanced or incorrect reporting on vaccinations. The physician-patient relationship may offer the best opportunity to educate and “influence the vaccine-hesitant.”

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Written by sciencepolicyforall

October 21, 2016 at 9:34 am

Posted in Essays

Tagged with , , , , ,

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