DT Next Explains: Here's all you need to know about Zika, Nipah and Chandipura viruses

CHENNAI: The Chandipura virus has claimed 16 lives in Gujarat. A 14-year-old boy in Kerala died due to Nipah virus. And, more than 38 cases of Zika virus have been reported in Maharashtra.

Easy transmission and high rate of infection by these 3 viruses have put the health departments in other states, including Tamil Nadu, on high alert.

Since viruses don’t vanish completely, public health experts opined that an increase in the human-animal interference and presence of viruses in environmental reservoirs can lead to a recurrence of the infection several years later too.

“In a favourable climate, these viruses tend to grow and impact human beings upon transmission. Environmental factors and climate change have led to an increased conflict between humans and animals. There is no need to panic but caution is important,” said a senior official from the State Health Department in TN.

Gopal Dhinakar Raj, veterinary scientist and retired professor from Tamil Nadu Veterinary and Animal Sciences University, averred that the increase in human-animal interference enables the virus to resurface again and again, leading to an increase in zoonotic infections.

“New transmissions take a long time to impact humans and cross-species transmission does not succeed often. It brings a new environment for the pathogen to survive so it takes a very long time for new transmissions,” he pointed out. “However, resurfacing of old viruses happens easily because the human body has already been exposed to it. Once it overcomes the immunity system, they can infect humans.”

Zika Virus Disease

A mosquito-borne viral disease, Zika Virus Disease (ZIKV) is caused by the Zika virus, which is primarily transmitted through the bite of an infected female Aedes mosquito.

The first trace of the virus goes back to 1952-53, as a study published in the Journal of Immunology in April 1954 showed the presence of antibodies against Zika.

The study revealed that one sixth of the tested blood samples showed immunity to the virus, indicating the infection earlier. Out of 13 samples tested, one from Tiruvallur was found to have antibodies against Zika.

Zika virus was reported in India in 2017 with several people being infected in Gujarat at first, and then sporadic outbreaks reported in different parts of the country, including Tamil Nadu, Rajasthan, Madhya Pradesh, Tamil Nadu, Karnataka, Kerala, Delhi, Uttar Pradesh and Maharashtra.

Currently, other than symptomatic treatment, there is no vaccine or drug available to prevent or treat the disease.

Symptoms

• Fever, skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache
• Lasts upto 2-7 days
• Transmitted from mother to foetus, through sex and also blood transfusion.
• Incubation period of the virus is 2-7 days but may extend to a few weeks
• One out of five people may develop symptoms, but the health department guidelines say that the disease is usually mild, with approximately 80% of people with the infection being asymptomatic
• Newborns can develop microcephaly, and other neurological syndromes such as Guillain Barre Syndrome (associated with ZIKV in some cases)

Nipah Virus

A zoonotic virus belonging to the Paramyxoviridae family, Nipah virus can cause severe respiratory and brain diseases in humans. Large fruit bats of Pteropus genus are the natural reservoir of Nipah virus.

The infection to humans may occur after direct contact with infected bats, infected pigs, or from other infected people.

The first case was recorded in 1998 in Malaysia and Singapore. It was initially identified as a mysterious illness affecting pig farmers and veterinarians in Malaysia, and later detected in Singapore among abattoir workers who had handled imported pigs from Malaysia.

The outbreak in Malaysia occurred from September 1998 to April 1999, resulting in 265 cases and 105 deaths. In Singapore, there were 11 cases and one death.

The virus was isolated and identified as a new member of the Paramyxoviridae family in 1999, and was named Nipah virus after the village of Kampung Sungai Nipah in Malaysia, where the first case was reported.

In India, two outbreaks were reported during 2001 and 2007 in West Bengal. In 2018, there was an outbreak in Kozhikode and Malappuram districts of Kerala, with 18 confirmed cases and 17 deaths.

On July 12 last year, the Central Surveillance Unit, National Centre for Disease Control, Ministry of Health and Family Welfare declared a Nipah virus outbreak in Kozhikode and Malappuram districts again. Two fatalities have been reported in Kozhikode.

A few days back, one more 14-year-old patient had died due to the Nipah virus infection.

Currently, there is no specific treatment or vaccine available, but early diagnosis and supportive care can improve survival chances. Wearing protective gear and avoiding close contact with sick animals could also help.

Symptoms

• Headache, cough, sore throat, breathlessness, and encephalitis
• Spreads through direct contact with infected animals such as bats, pigs, and horses, consumption of contaminated food items such as fruits and raw date palm sap, and also transmission through close contact with an infected person’s bodily fluids
• Infection detected through RT-PCR on respiratory secretions, urine and cerebrospinal fluid.

Chandipura Virus

Primarily affecting children, the Chandipura virus is a member of the Rhabdoviridae family. The rare viral disease results in encephalitis in humans, and is transmitted through the bite of an infected sand fly.

The first case of Chandipura virus was reported in 1965 in Chandipura, Maharashtra, and was named after the city. Since then, outbreaks have been reported in Gujarat, Maharashtra, and Andhra Pradesh.

In July 2024, Sabarkantha district of Gujarat reported a Chandipura Virus Encephalitis outbreak among children. This has raised significant public health concerns due to the rapid spread and the severity of symptoms with high mortality rate. So far, 15 cases and 8 deaths have been reported in Gujarat.

There is no specific treatment or vaccine available for Chandipura virus, but using repellents to prevent sand fly bites can offer protection against the virus. In the case of infection, supportive care is crucial.

Symptoms

• Fever, headache, vomiting, seizures and encephalitis
• Usually transmitted through the bite of infected sand flies or mosquitoes and ticks, upon direct contact with infected animals or humans and also due to contaminated food and water
• High mortality rate ranging from 50-75% and primarily affects children under the age of 15 years
• Coma and death in severe cases within 24-72 hours of the onset of symptoms