Tamil Nadu has reported its first case of Zika virus in a 27-year-old man in N. Puttur, Natrampalayam Panchayat, Denkanikottai Taluk in Krishnagiri district.
Subsequent tests at the National Institute of Virology, Pune, found the urine sample positive for Zika.
Earlier three cases of Zika had been detected in Ahmedabad, Gujarat in January.
Zika virus is a mosquito-borne flavivirus that was first identified in Uganda in 1947 in monkeys through a network that monitored yellow fever. It was later identified in humans in 1952 in Uganda and the United Republic of Tanzania.
The first large outbreak of disease caused by Zika infection was reported from the Island of Yap (Federated States of Micronesia) in 2007.
In July 2015 Brazil reported an association between Zika virus infection and Guillain-Barré syndrome.
Zika virus is primarily transmitted to people through the bite of an infected Aedes mosquito, which can also transmit chikungunya, dengue and yellow fever.
Zika virus can also be transmitted through sex and has been detected in semen, blood, urine, amniotic fluids, saliva as well as body fluids found in the brain and spinal cord.
Zika virus may present a risk to blood safety. People who have donated blood are encouraged to report to the blood transfusion service if they subsequently get symptoms of Zika virus infection, or if they are diagnosed with recent Zika virus infection within 14 days after blood donation.
The Aedes aegypti mosquito is considered the main vector of Zika virus transmission because it sustains most Zika virus outbreaks. Zika virus may be imported by infected travellers into an area that may not have Zika virus transmission at that point of time. If those travellers are bitten by local Aedes aegypti mosquitoes the mosquitoes can transmit the virus to others, potentially setting off a cycle of transmission.
Zika virus and its complications such as microcephaly and Guillain-Barré syndrome represent a new type of public health threat with long-term consequences for families, communities and countries.
Microcephaly is a condition where a baby’s head is smaller than those of other babies of the same age and sex. Microcephaly happens when there is either a problem in utero, causing the baby’s brain to stop growing properly, or after birth when the head stops growing properly.
Children born with microcephaly often have developmental challenges as they grow older. In some cases, children with microcephaly develop entirely normally. Microcephaly can be caused by a variety of environmental and genetic factors such as Down syndrome; exposure to drugs, alcohol or other toxins in the womb; and rubella infection during pregnancy.
Guillain-Barré syndrome is a rare condition in which a person’s immune system attacks his or her nerves. People of all ages can be affected, but it is more common in adult men.
Categories in the Zika virus country classification scheme (WHO):
Category 1: Area with new introduction of Zika virus since 2015 or area where the virus has been re-introduced, with ongoing transmission.
Category 2: Area either with evidence of Zika virus circulation before 2015 or with transmission but the area does not satisfy the criteria for 1 or 3. Areas in category 2 may also experience an outbreak of Zika.
Category 3: Area with interrupted transmission but with potential for future transmission.
Category 4: Area with established Aedes aegypti mosquitoes but no known documented past or current transmission.