The southern Indian state of Kerala has issued an alert after it confirmed that two people have died from the rare Nipah virus.

One of the deaths occurred earlier this month while the other took place on 30 August, both in the state's Kozhikode district, officials said.

Two relatives of a victim have also tested positive for the virus and are being treated in hospital.

The is the fourth Nipah outbreak in Kerala since 2018.

The Nipah virus infection is a "zoonotic illness" transmitted from animals like pigs and fruit bats to humans, according to the World Health Organization.

It can also be transmitted through contaminated food and through contact with an infected person.

People who contract the virus sometimes show no noticeable symptoms, while others show signs of acute respiratory problems. In severe cases, a Nipah infection can result in foetal encephalitis - a serious condition that affects the brain.

The mortality rate among those who contract the virus is high as there is no medicine or vaccine available to treat the infection. Treatment is limited to managing symptoms and supportive care.

India's Health Minister Mansukh Mandaviya on Tuesday said the federal government had dispatched a team to experts to Kerala to assess the situation and assist the state government in managing the outbreak.

The state's Health Minister Veena George said on Wednesday that tests had shown that the virus strain in the current outbreak was the same as the one found in Bangladesh earlier.

She also said that teams from the National Institute of Virology in the western city of Pune would set up a mobile lab at Kozhikode Medical College to test for the virus and carry out surveys on bats.

Ms George has said that 168 contacts of the two people who died have been identified and are being tested for the virus.

The state government has set up a control room in Kozhikode to monitor the situation and health workers have been instructed to follow infection control protocols.

Seven villages in Kozhikode have been declared containment zones and authorities have shut some schools and offices in the district, Reuters news agency reported.

Kerala Chief Minister Pinarayi Vijayan said the state government was taking the deaths "very seriously" and asked people to exercise caution by wearing face masks and visit hospitals only for emergencies.

But he added that there was no reason to panic as people who were in contact with those who had died due to the virus were undergoing treatment.

Kozhikode reported its first - and the worst - Nipah outbreak in 2018 when 17 of the 18 confirmed cases died.

In 2019, one case was reported in Ernakulam district and the patient recovered. But in 2021, a 12-year-old infected boy in Chathamangalam village died.

An investigation published by Reuters in May found that Kerala, which is a tropical state and is witnessing rapid urbanisation and rapid tree loss created "ideal conditions for a virus like Nipah to emerge".

Experts say that due to habitat loss, animals are living in closer proximity to humans and this helps the virus to jump from animals to humans.