NEW DELHI: A benign version of the Zika virus, which hit the headlines after an outbreak in several countries in 2015-2016, is likely residing within thousands of people in India and could lead to a public health concern in a few years, a study has found.
The study, which tries to explain why the virus remains hidden, says that India’s Zika is genetically distinct from two other pathogenic global strains -- African and Asian -- as it is unable to efficiently infect mosquitoes.
This discovery by the Indian Council of Medical Research and the National Institute of Virology, Pune, has explained why despite more than a year of surveillance and screening of over 35,000 samples, only four cases have been detected in India.
“India’s Zika virus strain does not replicate profusely as do the foreign Zika strains and mosquitoes do not pick up and transmit the Indian Zika virus strain with efficiency and therefore cannot spread it profusely as they do chikungunya and dengue viruses,” says a paper on the study published this month.
The scientists have also cautioned that if India’s Zika strain mutates to more efficiently infect mosquitoes, it could become a major public health problem in the future -- in the same way that chikungunya re-emerged in India about a decade ago after years of dormancy.
The scientists say it is possible that the four cases are only the “tip of the iceberg,” and there may be many patients who have not developed symptoms.
They add that it may be useful to make microcephaly — a condition in babies where the head is significantly smaller than expected — a notifiable disease and use it to estimate the burden of Zika in the country.
In early 2015, a widespread epidemic of Zika virus, which started in Brazil, spread to other parts of South and North America. It also affected several islands in the Pacific, and Southeast Asia.
In February 2016, the World Health Organisation declared the outbreak a public health emergency of international concern as evidence grew that Zika could cause birth defects as well as neurological problems.
The virus can be transmitted from an infected woman to her foetus and cause microcephaly and other severe brain anomalies in infants. In adults, it can lead to Gullain-Barre syndrome, in which the body’s immune system attacks nerves, leading to several complications.