Zika and wildlife
The book adds to the mystery of the Zika virus and its vector
We review two new books—one on the Zika virus and the other on the mismanagement of India's wild spaces
IT'S A book that attempts to answer the questions around the Zika virus, its vector and the disease it causes. Where did it come from? Where has it been hiding for so long? Why has it become so deadly this time? What have researchers learned about the virus, its vector and its alternate host? When did it come to India? In truth, there are no easy answers to these questions, but the author brings out the complexity of viral, vector-borne diseases like the chikungunya, dengue and Zika fevers. The Secret Life of Zika Virus puts things in perspective. Though we know that zoonotic diseases emerge from a degraded environment, we continue to wilfully destroy habitats such as forests. And each new disease is turning out to be deadlier than the one before. While the dengue virus and the chikungunya virus immobilise, and even kill, the patient, Zika goes a step beyond— it harms the unborn child. The infection triggers microcephaly in children born to infected mothers. These children are born with a small skull and a deformed brain.
The book starts with three cases—two women and a man—reported in India in May 2017. In November, 2016, one of the women had just delivered a baby when she fell sick, while the other woman tested positive in January 2017 during her pregnancy. Unless we know about the disease, we cannot protect these children.
Unfortunately, we don’t. We have known about the Zika virus as far back as in 1947, when it was isolated from the Zika Forest in
The Zika virus usually attacks the placenta as the defence of this tissue is not very developed. Since it does not make evolutionary sense for the virus to kill the foetus, it infects the foetus and deformed babies are born
Uganda. Researchers at the Uganda Virus Research Institute were trying to understand the yellow fever. But they did not explore the unrelated symptoms such as inactivity, rough coat and paralysis in inoculated mice and also ignored that the younger mice were more affected. There is a reason the virus affects the baby profoundly even though the symptoms experienced by the mother are very benign. Three places in the human body are easier to invade: the brain, the genital tract and the placenta. The Zika virus usually attacks the placenta as the defence of this tissue is not very developed. Since it does not make evolutionary sense for the virus to kill the foetus, it infects the foetus and deformed babies are born. Since 1947, the virus has been spotted across the world. It was reported in India in 1954. But there were no reported cases of fever caused by the virus anywhere outside Africa. It was only in the early 1970s that fever cases were reported from Indonesia. The book talks about the disease in the Ame-ricas, much before the virus was identified in the Zika Forest. Information about Christopher Co-lumbus’ second journey to America in 1494 suggests he suffered an illness that led to arthritis. The authors say that this could be due to chikungunya, dengue or the Zika virus. Images of the microcephalic Aztec man are common and Co-lumbus had even mentioned the fact that people in the area lacked intelligence and were easy to control. This could mean that the virus is of Am-erican origin. Then the authors go on to figure out where the vector, Aedes aegypti, came from. It is quite likely that it came from Africa and equally likely that it originated from Asia. But the more pertinent question that one would ask is whether the Aedes is actually the vector. Though three cases in India have been reported in India, the 12,647 mosquitoes tested for the presence of the virus in the country have tested negative for the presence of the virus. In 2007, the island of Yap in the Pacific Ocean reported a fever. The population of the island is small and it was possible to test each person for the causal pathogen. When they tested, it was found that three-fourths of the population had the Zika virus. However, none of the mosquitoes tested positive for the virus. This could mean that the disease not only spreads through the very common Aedes, but it also spreads through an alternate vector, about which we know nothing. Now consider this question: does the Zika virus cause microcephaly? In Brazil’s current epidemic, of the 4,783 babies initially identified as microcephalic, 1,103 were investigated. But viral particles were found only in 19 babies. What then is causing the disease? There are no answers. As you go through the book, be prepared to be drawn into a world of history, science, war and slaves. Everything is threaded in a single narrative. Often, you may find interesting information, which has little significance to the disease. But surrender to the story and it will make sense, even the personal anecdotes.