Is Zika here to stay? More than 131 people have tested positive in Jaipur’s Shastri Nagar and Sindhi camp neighbourhoods over the past one month, raising fears of the viral infection becoming endemic to cause annual outbreaks.

There are reasons for concern. For one, the environmental conditions in India are conducive not just for the virus to thrive but also the mosquito that spreads it.

Zika is a mosquito-borne virus that belongs to the Flaviviridae family, which includes dengue and Japanese Encephalitis viruses. It thrives in tropical conditions and causes disease in the Pacific islands, Africa, South America and south and south-east Asia.

The disease is spread by the aedes aegyti mosquitoes, which also spreads dengue and chikungunya. So a Zika outbreak can potentially occur in all the places that have reported dengue or chikungunya.

What’s as worrying is the likelihood of Zika being missed or misdiagnosed even in clinical settings because around 80% of those infected have no symptoms and those who fall ill have mild and non-specific symptoms.

Zika infection may cause fever, rash, joint and muscle pain, headache and conjunctivitis , with the symptoms typically lasting two to seven days. The treatment is symptomatic and there is no vaccine. It has caused no deaths. Hundred and seventeen of the 131 infected people in Jaipur have recovered.

Zika virus infection was not an issue of public health concern until the infection in pregnant women was linked with microcephaly, a birth defect in which the baby’s head is smaller than normal because of abnormal brain development. Pregnant women who get infected also risk their unborn baby, having a stillbirth or preterm birth. In adults and older children, it can cause neurological disorders including Guillain-Barré syndrome, and myelitis .

With 26 million births each year and one in five of the deliveries still happening outside a health centre or hospital, hundreds of thousands of babies will be at risk of microcephaly and neurological abnormalities if the infection takes root in India.

Zika was first identified in monkeys in Uganda in 1947 and in humans in Uganda and Tanzania in 1952. From the 1960s to 1980s, caused mild fever across Africa and Asia, but the 2015-16 outbreak in Brazil and South America linked the infection to microcephaly in newborns and GBS, which promoted WHO to declare the Zika a Public Health Emergency of International Concern on February 1 to November 23, 2016.

Zika has been reported in 86 countries, with the first confirmed case in India in Gujarat in February, 2017, when three people tested positive in Ahmedabad, which was followed by one case in Krishnagiri district in Tamil Nadu in July of the same year.