How did the Zika virus get to India? Or has it always been here?

Thursday, 1 June 2017

The three people found infected with the Zika in Ahmedabad, Gujarat have no history of travel to Zika-affected countries. The implication of this is that that the transmission of the Zika in Ahmedabad could be local and that the disease is already prevalent in the area, said experts. This view is based on recent analyses of a 1954 report that indicated that Zika virus could have circulated in the India in the past. However, its findings are inconclusive.

Zika is a viral disease transmitted by the bite of an Aedes mosquito and can also be sexually transmitted. The Zika virus generally causes a mild and temporary infection in adults with symptoms like fever and rashes. But Zika infections have also been linked to incidences of Guillain-Barré syndrome, a nervous system disorder caused by a person’s own immune system attacking nerve cells, causing muscle weakness, and sometimes, paralysis. The biggest danger from the Zika virus is to pregnant women and their foetuses. Zika infections in pregnant women can lead to congenital defects in in their newborns such as microcephaly, in which the brain of the infant is small and underdeveloped.

As per guidelines issued by the Government of India to prevent and control Zika, the Integrated Disease Surveillance Programme should track clustered cases of acute febrile illness, which are people having fever, chills and joint pain. The programme is supposed to do this by gathering data from communities and hospitals. Surveillance for Zika also involves looking for people who have travelled to areas with ongoing transmission such as Brazil and Mexico.

“We checked if the patients travelled to these countries within the incubation period of the infection,” said Dr AC Dhariwal, director of National Centre for Disease Control. “Since there was no history of travel, the transmission is presumed to be local.”

Dhariwal said that the Zika virus strain found in the three Ahmedabad cases is of Asian origin. This strain was one of the many found in Brazil, which had one of the biggest outbreaks in 2015 and an abnormal rise in the cases of microcephaly.

“But the same strain was also found in Singapore last year,” clarified Dhariwal. “The cases were milder there.”

In response to queries by Scroll.in, a spokesperson for the World Health Organisation country office in India said in an email that cases of Zika in India are not unexpected since all countries with Aedes mosquitoes are at risk for local Zika virus transmission.

“Although Zika is no longer a Public Health Emergency of International Concern, WHO maintains that vigilance to Zika needs to remain high,” said the spokesperson in an email response. “Reporting of Zika cases reflects the country’s efforts to implement key WHO recommendations related to surveillance as well as their commitment to the International Health Regulations, which requires all member countries to report public health events to WHO.”

India did report the cases to WHO but more than four months after the first case in the country was confirmed.