Between November 2016 and February 2017, three people in Ahmedabad, Gujarat, tested positive for the Zika Virus. The first was a woman who developed a fever after delivering a baby, and who recovered within a week. The other two cases—a pregnant woman in her early 20s, and a 65-year-old man—were identified during screenings conducted in January and February 2017. The existence of these cases however, was not publicly known until much later—on 26 May, the World Health Organisation published a report regarding these cases on its website. The WHO said that the Indian government had notified it of the cases only in mid May—over six months after the first case was diagnosed. The report was followed by a significant outrage among the public-health community, much of which was severely critical of the government’s delay in informing WHO.
Zika is a vector-borne virus—it is transmitted by a living organism—which can lead to microcephaly, a birth defect due to which children develop unusually small heads and resultantly, neurological defects. A Zika epidemic broke out in Brazil in 2015, during which over 50 children were born with microcephaly. Countries such as Brazil and India, due to their dense population and tropical climates, are particularly prone to the spread of such a virus. In the book The Secret Life of Zika Virus, Kalpish Ratna examines the evolution of the Zika virus, and what India can learn from the spread of the disease in Brazil. In the following extract, Ratna examines two ways to read an epidemic: one is scientific, and the other, personal.
This extract is part of The Caravan’s short series on Zika. The series includes a photo essay on the lingering effects of the virus in Recife, Brazil, and a reporton why the Indian media’s response to the emergence of Zika in India fell short.
Perhaps the time is right to step back a little and review what a year of living with Zika has meant. How do we read an epidemic?
The index used to gauge the transmissibility of a disease, and therefore the progress of an epidemic, is called the Basic Reproductive Number, R0 (R Naught). This number quantifies how many other individuals one patient can infect with an illness.