This is a pre-submission version of our recent letter to the Lancet. The final published version can be accessed here.
Following widespread criticism about inadequate action during the Ebola epidemic in West Africa(1), the global response is once again being tested by two re-emerging infectious disease threats in the form of Zika and yellow fever viruses. The public health and scientific response has been unprecedented. On 1 February 2016, the World Health Organization (WHO) declared a Public Health Emergency of International Concern (PHEIC)(2) in regard to the then suspected link between Zika virus infection and congenital and neurological complications, most notably microcephaly and Guillain-Barré syndrome (GBS). The current resurgence of yellow fever in Central Africa, though not currently considered a PHEIC, has also triggered a strong response in the form of mass vaccination campaigns in Angola and the Democratic Republic of Congo (DRC). As of 1 September 2016, more than 10 million people have been vaccinated against yellow fever in these two countries. Calls by the WHO’s International Health Regulations Emergency Committee for rapid sharing of data related to Zika virus have also been largely heeded, both by health authorities and researchers, and facilitated by agreements from major publishers to make openly accessible all data related to Zika virus(3). New and critical information is emerging weekly regarding the expanding spectrum clinical manifestations of Zika virus infection, pregnancy-associated risks of infection and congenital abnormalities, viral pathogenesis, the role of non-vector-borne transmission modes, predictions of geographic expansion and health burden, and the development of diagnostics and vaccine candidates. In turn, these are resulting in improved recommendations for the control and management of Zika virus disease and its complications that are updated with the latest evidence.
As the Zika epidemic enters a new phase of sustained transmission in Asia, however, these two emergencies also point to major gaps in our ability to contain the geographic spread of new and emerging infections. To date, there have been 11 official reports of inadequately vaccinated Chinese workers diagnosed with yellow fever after returning to China from postings in Angola. In Singapore, the first cluster of locally-transmitted Zika virus infection, reported on 27 August 2016, was characterised by involvement of a large number of migrant workers in the construction industry. These examples highlight the potential dangers of infectious diseases following the geographic movements of migrant workers. The International Labour Organization (ILO) estimates that there are 150 million migrant workers globally, a fifth of whom are located in Asian countries excluding the Middle East.(4) A quarter of migrant workers are in the manufacturing and construction sector. The status of migrant workers as a vulnerable population is codified in the International Convention on the Protection of the Rights of All Migrant Workers and Members of Their Families, but out of the 48 ratifying states, none is a net importer of labour. Construction workers in particular live and work in conditions known to be highly permissive for transmission of vector-borne diseases. In Singapore, contractors can be heavily penalised for allowing mosquito breeding on construction sites. In 2015 alone, more than 100 Stop Work Orders were issued to construction sites found to be breeding mosquitoes, as well as more than 900 Notices to Attend Court and 100 prosecutions for repeat offences regarding mosquito breeding in construction sites.(5) But often, preventive measures, screening and healthcare for workers is under the purview of employers in the private sector, which are not best placed and should not be relied upon to protect the wider public health in the context of a rapidly changing international emergency. At the heart of this are also issues of power and trust: while workers have access to some forms of health care, these are often provided by employer-contracted providers, who are often seen as colluding with employers against the best interests of workers.(6) Punitive measures that result in fear of dismissal or deportation are also likely to add as a deterrant to workers to come forward for diagnosis and treatment when symptomatic. And where workers are able to access care, this should be evidence based, empowering, and sensitive to their needs.
The introduction of sustained yellow fever transmission in Asia would have disastrous consequences, while the risk of sexual transmission of Zika virus once infected workers return to their home countries should not be underestimated. In this context, the international community should work to develop specific guidelines for vulnerable populations such as migrant workers who in the course of employment experience an increased risk of infection in a foreign country and inadvertently pose a risk of onward transmission upon returning to their home country. In the context of the current Zika outbreak, this should at a minimum include provisions for employers and health providers to give adequate counselling to workers returning from Zika-affected areas and their sexual partners, particularly with regard to the prevention of onward transmission. Better intersectoral coordination can ensure that evidence-based recommendations are adhered to in a manner that protects the public health and respects the rights and cultural sensitivities of this vulnerable population. Where economics and epidemics collide, we owe a duty of care to those caught in the middle.
Clarence C Tam1,2, Mishal S Khan1,2, Helena Legido-Quigley1,2
1Saw Swee Hock School of Public Health, National University of Singapore, Singapore
2London School of Hygiene & Tropical Medicine, London, United Kingdom
1. Clift C. Is Yet Another Ebola Report a Symptom of the Problem or the Solution? | Chatham House [Internet]. Available from: https://www.chathamhouse.org/expert/comment/yet-another-ebola-report-symptom-problem-or-solution
2. WHO statement on the first meeting of the International Health Regulations (2005) (IHR 2005) Emergency Committee on Zika virus and observed increase in neurological disorders and neonatal malformations. WHO. World Health Organization; 2016.
3. Dye C, Bartolomeos K, Moorthy V, Kieny MP. Data sharing in public health emergencies: a call to researchers. Bull World Heal Organ. 2016;94:158.
4. International Labour Organization. ILO global estimates on migrant workers. Geneva; 2015.
5. Ministry of the Environment and Water Resources. Parliamentary Q&A: Oral Reply by Mr Masagos Zulkifli, Minister for the Environment and Water Resources, to Parliamentary Questions on Dengue [Internet]. 2016. Available from: https://www.mewr.gov.sg/news/oral-reply-by-mr-masagos-zulkifli–minister-for-the-environment-and-water-resources–to-parliamentary-questions-on-dengue
6. Ho O. Worker with crushed finger gets just 1 day off, Manpower News & Top Stories – The Straits Times [Internet]. The Straits Times. 2016 [cited 2016 Sep 9]. Available from: http://www.straitstimes.com/singapore/manpower/worker-with-crushed-finger-gets-just-1-day-off