Last week the Daily Herald reported that two cases of chikungunya virus CHIKV were laboratory confirmed on St. Martin. The article stated that CHIKV is in the Pacific Islands, Asia and India, but until now not in the Caribbean islands. While it is true that these are the first laboratory confirmed cases of CHIKV in the Caribbean, it is highly probable that the virus has been circulating in the Caribbean for some time. Not documenting the virus sooner probably results from a failure to invest in public health research and infrastructure.
CHIKV is similar to dengue virus DENV in that it is a viral disease transmitted by mosquitoes. Like DENV, CHIKV is what is called an ARBO virus. ARBO viruses are transmitted to humans through the bite of blood sucking vectors such as mosquitoes and other biting flies or ticks. There are over 400 types of ARBO viruses (although all are not a threat to humans). While every year each country is supposed to report prevalence, incidence, morbidity and mortality data to the Pan American Health Organisation (PAHO), the difficulty surrounding ARBO viral diagnosis causes many potential problems when data is compiled in each respective country.
According to the World Health Organisation (WHO) there is a great deal of variability in the clinical illness associated with ARBO viral infections, and it is not appropriate to adopt a detailed definition of what constitutes a definite diagnosis. Laboratory confirmation is emphasised. Additionally, many clinical signs can result in differential diagnoses as it is difficult to distinguish many ARBO viral infections clinically from each other and a wide spectrum of other bacterial and parasitic infections.
There are also no single, simple diagnostic criteria available. In a laboratory, ARBO viruses are diagnosed by isolation of the virus, by serology or by molecular diagnostic methods. However, tests requiring the identification of the virus or the viral genome are expensive and require specialised laboratories. While, there are some commercial kits available for diagnosis many concerns surround their validity resulting from inadequate sensitivity and specificity. Simply stated, often times, the results of these tests result in missed diagnosis.
In 2000, the 42nd Directing Council of PAHO adopted resolution CD42.R14 urging countries to participate in the regional exercise to measure performance with respect to 11 defined Essential Public Health Functions (EPHF). This exercise would allow countries to carry out interventions to develop their capacity and improve public health practice. In the sub-region of the English-speaking Caribbean and Antilles, countries exhibited low-intermediate performances in nearly all of the essential public health functions with only one function, reducing the impact of emergencies and disasters in health perform adequately (EPHF 11). The lowest performance was exhibited in the areas of public health research and quality assurance (EPHF 9, EPHF 10).
Despite the growing threat from emerging/re-emerging ARBO viruses, 14 years after the PAHO resolution, very few laboratories in the region have capabilities for diagnosing highly infectious diseases such as viral haemorrhagic fever, severe acute respiratory syndrome, etc. Countries often ship specimens to other regions for confirmation resulting in delayed responses to outbreaks. Laboratory-based surveillance would play a significant role in timely outbreak response and the regular analysis of laboratory data would allow for the prediction of circulating disease characteristics for citizens and the region.
In the Caribbean region the control and prevention of HIV/AIDS (reproductive health) is a priority area for infectious disease funding. HIV/AIDS is an important concern as the Caribbean region is the second most affected region in the world in terms of HIV prevalence rates. Based on 2009 data, about 1.0 per cent of the adult population (240,000 people) is living with the disease.
However, due to the nature of how ARBO viral diseases are spread (a bug bite), it is critical that an investment be made in public health infrastructure and research so that evidenced based ARBO viral control and prevention can become priority areas.
This effort must not be left to single islands but rather one of the entire Caribbean community. It is my suspicion that many ARBO viruses have been circulating and continue to actively circulate in the Caribbean. It is now time to come together as a Caribbean community and work towards prevention and control. This can be accomplished through investments in public health research laboratory capacity, improvements in communication networks and increased data sharing.
Dr. Teresa E. Leslie
President and Founder
Eastern Caribbean Public Health Foundation, St. Eustatius.