Zika is no longer a medical emergency for WHO. What is the situation in India?
The virus remains a threat. But the emergency was called off as the virus is here to stay, and long-term effort is required to address it. A rigorous surveillance programme must be in place to prepare for any outbreak of the virus. However, Zika is not a priority as compared to diseases such as dengue and chikungunya. In India, after testing approximately 35,000 samples, we have found three positive. This indicates that Zika is not as highly prevalent as dengue and chikungunya.
Doesn’t India have the right climate and abundant mosquitoes that carry the Zika virus (ZiV)?
In urban settings, where the aedes aegypti (which carries the virus) is abundant, ZiV has the potential to cause an outbreak. However, in the absence of recent serological data from India, or virus isolations, it is difficult to predict the potential impact of ZiV in the country. Most people do not show any specific symptoms, and only one in five people infected may develop a mild disease. The most common symptoms are fever, rash, joint pain and conjunctivitis. Serious mortality and morbidity is not associated with this virus.
But we now have laboratory-confirmed cases of ZiV disease in the country.
When a pathogen is recognised as emerging in any part of the world, an alert goes out, and efforts start to detect its presence in other areas. Zika may not be a recent introduction to India — sometimes diseases are present but are not known. Back in 1953, NIV (then known as Virus Research Centre) had tested blood samples from localities with more than average rainfall against 15 viruses. Zika was one of them. In Bharuch district of the then Bombay state, Gujarat and Nagpur, antibodies against the virus were detected. Again, the Chandipura virus, associated with encephalitis, which had a high fatality rate among children in central India in 2003-04, was first recognised in the 1950s. Similarly, studies showed that the Crimean-Congo haemorrhagic fever (CCHF), which was identified in 2011 in India, had been present in the country for a long time. With such examples from history for arboviruses [viruses that are transmitted by mosquitoes, ticks, or other arthropods], it is difficult to predict the extent of Zika’s impact.
Zika has been shown to trigger microcephaly (a birth defect where a baby’s head is smaller than expected when compared to babies of the same sex and age) in babies born to mothers infected with the virus while pregnant. Is that a major concern?
Research has shown some link between ZiV fever and microcephaly in newborns by mother-to-child transmission, as well as neurological conditions in infected adults, including cases of Guillain-Barre Syndrome (in which the body’s immune system attacks part of the peripheral nervous system). But again, there are just three cases in the country, and two women who were infected delivered healthy babies. There is no need to panic. Research is under way worldwide on ZiV. In a paper published in the Indian Journal of Medical Research in May last year, I explained that answers to various questions will emerge only with time. This virus has lived a ubiquitous life for decades in tropical and equatorial zones, and the presence of antibodies has been reported in Africa and Asia. It has not shown dramatic evolutionary mutations, but the vector biology and disease pathogenesis of ZiV is far from clear. There are no data on birth prevalence of ZiV, and its possible relation with congenital infection in the country. Hence, the level of preparedness is being stepped up.
What steps can be taken other than those by the Indian Council of Medical Research (ICMR) towards enhanced human surveillance for ZiV?
Citizens have to ensure there is no mosquito breeding on their premises. Hospital-based surveillance is important but surveillance of mosquitoes is extremely challenging. There is need to impose penalties in case mosquito-breeding is found in buildings, societies or even homes. This is a tool in our hands to reduce the source of the disease.
Pune-based National Institute of Virology (NIV) conducts research on human viruses of public health concern, including re-emerging viruses such as Chandipura, H1N1, Japanese Encephalitis, Dengue, avian influenza, etc., all of which cause considerable mortality and morbidity. NIV confirmed India’s first three cases of Zika virus infection — all in Ahmedabad.