All about Zika
after hundreds of babies with undersized heads were born in Brazil. The writers claim that Zika virus — the name comes from Zika Forests in Uganda — is not new to India and has been here since at least 1953. However, only three confirmed cases have been reported thus far. One was in November 2016 when a 34-year-old women was tested positive for Zika after having delivered a normal infant. She recovered a week later. Another pregnant woman was found infected with Zika in January 2017, but the government has not released any information about her or the baby. The third case relates to a 64-year-old man who was found carrying Zika during a surveillance drive by the Ahmedabadbased B J Medical College.
These cases only came to light after the Union government reported them to the World Health Organization (WHO) in May this year. In light of this, the writers thought it a good idea to offer readers information on the source of the virus, its transmission and the potential damage it can cause. They have tried to stitch together research and scientific studies, some even dating back to the 14th and 15th centuries, and patterns of diseases across continents. They believe that a lot more research is required, but whatever information they have gathered during the course of their writing challenges the basic premise that the prime vector of the Zika virus is the Aedes aegypti mosquito, which also transmits dengue and chikungunya.
Unlike dengue and chikungunya, Zika can be sexually transmitted. “Zika can affect the developing brain of the unborn baby. It can produce a life threatening paralysis. It may have any, all, or none, of these effects. It may be totally benign, a mild fever that passes without a trace,” they write. Though, the sexual transmission has been inadequately investigated, Zika poses a serious threat to 24 million pregnancies each year in India. The researchers have already explored 43 strains of the Zika virus sampled between 1947 and 2007.
So should the governments eradicate the Aedes aegypti when the threat perception looms large? The writers think otherwise. They quoted an example of 18 countries, including Brazil, that eradicated the mosquito in 1962 using DDT spray on a war footing. Still Brazil encountered one million cases of dengue. “There are many exhaustive lists of reasons the exercise failed. But these always overlook the obvious: Aedes aegypti is a tree-hole dweller. Cut down a tree, and the evicted mosquito will move right in with you.”
Since Aedes aegypti is considered the prime transmitter of the Zika virus, the writers delved into its history of origin. This is where the book loses momentum. Though the writers tried to romanticise the sex life of mosquitoes, the effort is too ponderous to be compelling: “The wingbeat of the male mosquito is his love song. The female tunes her wingbeat to match that frequency. Romance is only sparked off when they are in tune with each other…The female exudes an aggregation pheromone that gets the guy going — not in groups of ten or twenty, but in thousands.”
The writers also tried to challenge the ancient wisdom that Aedes aegypti travelled from Africa to Americas during the slave trade as eggs in water casks on board ships in the midseventeenth century. The writers quote incidents to show that diseases such as yellow fever, the “granddaddy of viral diseases”, again caused by Aedes aegypti, existed in the Americas even before the slave trade.
The book gains pace in the second half when the authors chronicle the lives of researchers who lost their lives while studying viruses because they let mosquitoes bite them so that they could study the pattern of the disease. But it was not until 1927 that an infectious particle that could pass through a bacterial filter was discovered and called a virus. By 1948, researchers scientifically established that the vector for Zika virus was Aedes africanus, a close relative of Aedes aegypti.
The writers strongly feel that climate and environmental changes have been the drivers of dengue and chikungunya, and Zika appears no different. They believe the response to Zika has been knee-jerk and is incorrectly focused on mosquito control, or exhortations to avoid infected areas, sex and pregnancy at all costs. These are unimaginative and patently unworkable solutions. The writers conclude by saying the Zika phenomenon is nothing less than a planetary alarm and our response to it will decide Earth’s future. Kalpish Ratna Speaking Tiger 263 pages; ~299