The advent of a new tetravalent vaccine against the dengue virus has thrown new light into the evidence-based management of dengue. An article recently published in the New England Journal of Medicine revealed that this vaccine confers about 80% protection to children vaccinated between 4 and 16 years of age without any major side effects. It was a double-blind, placebo-controlled, randomised, multi-centre trial which included 20,017 participants from the dengue-endemic countries. However, apart from promoting the use of the vaccine, gaining control over dengue will also require a holistic approach that has to include within its ambit vector control and proper case management.
Dengue is essentially a tropical disease that occurs in the countries around the Equator; hot weather and intermittent rainfall favour the sustenance of Aedes aegypti — the vector transmitting the dengue virus —and Aedes albopictus, a minor contributor. Aedes eggs can remain dormant for more than a year and will hatch once they come in contact with water. Urbanisation, poor town planning, and improper sanitation are the major risk factors for the multiplication of such mosquitoes. Aedes mosquitoes cannot fly beyond a hundred metres. Hence, keeping the ambience clean can help prevent their breeding. Further, these mosquitoes bite during the daytime, so keeping the windows shut in the day hours is also useful.
Shortage of skilled manpower
Many other source reduction activities can be undertaken, including preventing water stagnation and using chemical larvicides and adulticides. These chemicals need to be applied in periodic cycles to kill the larvae that remain even after the first spray.
Unfortunately, the number of skilled workers available for such measures is low; many posts in government departments remain vacant despite there being a dire public health need. Due to this deficiency of manpower, active surveillance is not being done in India, says the National Vector Borne Disease Control Program.
Also, dengue cases are often under-reported due to political reasons and also to avoid spreading panic among the common people. Further, there is a lack of coordination between the local bodies and health departments in the delivery of public health measures. A comprehensive mechanism is required to address these issues.
Moreover, epidemiological measures are essential in the management of any communicable disease. Singapore uses one successful model of mapping and analysing data on dengue, using Geographical Information System (GIS). This involves mapping the streets with dengue cases for vector densities.
Dengue is mostly an asymptomatic infection, and only a very few develop severe disease. Those very young or very old and those who have a chronic ailment are at a greater risk of developing severe disease. But the worldwide case fatality rate is as low as 0.3%. The dengue virus has four serotypes and only a second infection with a different serotype will cause a severe disease.
Fluid management is the cornerstone in the management of severe diseases like dengue hemorrhagic fever and dengue shock syndrome. Here, the role of platelet depletion in exacerbating the condition of a patient is overemphasised even by many medical personnel. Contrary to the common belief, platelet transfusions are not needed even in cases of active bleeding, as per the guidelines of the World Health Organization (WHO). Coagulation abnormalities are not due to a reduction in the number of platelets alone. This is why the WHO recommends fresh whole blood or packed cell transfusion in the event of bleeding. The platelet count will increase automatically as fever subsides.
Alternative medicine drugs
Finally, despite the adequate and well-formed guidelines for the management of dengue cases by the WHO and the Indian government, the usage of complementary medicines like Nilavembu kudineer (a Siddha medicine) and papaya leaf extract are rampant among the people. Nilavembu sooranam , which reportedly contains about nine different substances, has been widely promoted for use to treat dengue fever despite the safety of and complex interactions among its different constituents not having been tested.
The efficacy of Nilavembu kudineer in the management of several other diseases is based on very primitive forms of research like case reports, in-vitro studies, and animal studies. There are case reports where Andrographis paniculata, an active constituent of Nilavembu sooranam , showed anti-fertility effects in animal models, causing abortion. Even meta-analysis of various studies has shown that there is no credible evidence for the use of papaya extract in dengue fever. However, for unknown reasons, even some pharmaceutical companies are being allowed to market papaya extract pills.
In Tamil Nadu, complementary medicine practitioners often argue that a proper double-blind, randomised, placebo-controlled trial cannot be conducted as it involves huge money and manpower. Though this argument is partially correct, patients cannot be treated as guinea pigs. For any medicine, safety is more important than efficacy. Every modern medicine drug has come out after rigorous safety and efficacy studies for around 10 years, with an informed declaration of the side effects. Hence, instead of carrying out distribution of medicines like Nilavembu kudineer , the government can concentrate its energies on other public health activities.
Modern medicine is not against any complementary medicine; when such a medicine is approved after rigorous testing, modern medicine will absorb it, and there are many examples of that. However, in the absence of evidence, the efficacy of such medicines remains in the realm of belief instead of science.
Dhileepan Selvarajan is a consultant physician and cardiologist based in Thiruvarur, Tamil Nadu
