Maharashtra reported 140 cases of the Zika virus disease in 2024, its highest since 2021, said a situation report published by the World Health Organization on Wednesday.

The state had reported one case in 2021, three in 2022 and 18 in 2023. It accounted for most of India’s 151 reported Zika cases in 2024, with Karnataka reporting 10 cases and Gujarat recording one.

The Zika virus is transmitted primarily by the Aedes species of mosquito, which bites during the day. Symptoms of infection include fever, rashes, headache and joint pain. The virus can also be transmitted sexually, from mother to fetus during pregnancy and through blood transfusions.

Most infections are asymptomatic, but the Zika virus can lead to serious complications such as congenital Zika syndrome, microcephaly in newborns and neurological disorders such as the Guillain-Barré syndrome.

In its report, the WHO cited data from India’s Integrated Disease Surveillance Programme and noted that Pune district was the epicentre of the outbreak with 125 cases. Ahmednagar reported 11 cases, while Kolhapur, Sangli, Solapur and Mumbai Suburban districts recorded a case each.

The Integrated Disease Surveillance Programme is a decentralised state-based system of surveillance for communicable and non-communicable diseases aimed at detecting early warning signs of infectious disease outbreaks.

Of Karnataka’s 10 cases, seven were in Bengaluru Urban while three were in Shivamogga. Gujarat’s lone case was in Gandhinagar.

On July 3, the Union government had issued an advisory for all states after the initial detection of cases in Maharashtra.

The National Centre for Disease Control has since been monitoring the outbreak, with state-level laboratories conducting surveillance. Vector control measures have also been intensified, particularly in affected areas, and authorities have been closely monitoring pregnant women who test positive for the virus.

As of December 31, no cases of microcephaly or Guillain-Barre syndrome were reported that could be associated with the Zika outbreak.

The WHO, however, said: “The State IDSP [Integrated Disease Surveillance Programme] Unit does not routinely disaggregate the number of ZVD [Zika virus disease] cases (e.g. pregnancy status), therefore the number of ZIKV [Zika virus] infection among pregnant women is unknown.”

The WHO advised enhancing mosquito control measures such as eliminating breeding sites, using insect repellents and protecting households with screens and nets. It also recommended that pregnant women practice safer sex or abstain from sexual activity to prevent transmission.

The health agency has not issued travel or trade restrictions related to the outbreak.