Now, one Zika case reported from Tamil Nadu, India

zika-microcephaly - Photo WHO

There seems to be low-level transmission of Zika virus in India

After three adults tested positive for Zika virus in Ahmedabad district, Gujarat in January this year, an adult male from Krishnagiri district in Tamil Nadu has now tested positive for the Zika virus. Zika infection in the 27-year-old male was diagnosed on July 1 this year. This is the first case of Zika virus infection from Tamil Nadu.

According to the State Health Secretary Dr. J. Radhakrishnan, the patient reported with fever and other symptoms generally associated with Zika infection and was treated as an outpatient at a remote primary health centre at Natrampalayam panchayat.

“His samples were first tested for dengue and Chikungunya but they turned negative. So we tested his blood and urine samples for Zika and they tested positive for Zika. We sent his urine samples to NIV [National Institute of Virology, Pune] and reconfirmed Zika infection. He has completely recovered and is doing well,” Dr. Radhakrishnan says.

Local transmission

“He has not travelled to countries or places where Zika virus transmission is currently going on. Preliminary investigation reveals that no one from his immediate family has travelled to any country where Zika virus is in circulation. We think it is due to local transmission,” Dr. Radhakrishnan says.

According to him, his wife had delivered three months ago and has tested negative for Zika.

Unlike in the three cases in Ahmedabad, the patient has been counselled. “Counselling of the patient was done. We have particularly counselled him about the possibility of transmitting the virus through sexual activity,” he says.

According to a report in The Hindu, approximately 200 suspected cases of the virus were tested at King Institute of Preventive Medicine and Research, Chennai, and this is the first one that has tested positive.

Low-level transmission in India

“There seems to be low-level transmission going on in India for years. Nobody has been looking for this virus in India till we saw the virus causing microcephaly in newborns in Brazil. We have tested nearly 40,000 samples so far but picked up only three cases in Ahmedabad and now one in Tamil Nadu,” says Dr. Soumya Swaminathan, Director-General of the Indian Council of Medical Research (ICMR). “It is possible that we may pick up more cases from different parts of the country, which would indicate that the virus is present in India.” Zika virus was first reported in India in the 1950s.

“We don’t know why the Zika virus has not caused the same problems like microcephaly in newborns and Guillain-barre syndrome in adults as seen in Brazil. It could be because the virus is different or due to host immunity [people already exposed to the virus and have developed immunity to the virus] or other factors. These are not fully understood,” Dr. Swaminathan says.

“It is early stage to speculate about the epidemiology and disease profile of Zika,” she says.

Screening for birth defects and microcephaly in newborns and Guillain-barre syndrome has just started. “A year from now we will have more data,” Dr. Swaminathan says.

Published in The Hindu on July 10, 2017