Diagnosis of Nipah virus infection in Kerala tougher than in 2018: Expert

Mid-2020 Covid-like panic is back in some parts of northern Kerala. In the wake of a fresh outbreak of the Nipah virus claiming two lives, Dr A S Anoop Kumar, the director of critical care medicine at Aster MIMS hospital in Kozhikode who played the foremost role in detecting the virus in 2018 and then containing its spread, says that unlike last time when patients had encephalitis symptoms, this time they displayed respiratory infections, making early diagnosis relatively difficult.

Two others who are infected with the virus – the second victim’s daughter and brother-in-law – are in an isolation ward in Kozhikode district, according to state health officials.

Kozhikode in north Kerala is the epicentre of the viral attack, this time as well as in 2018. Studies suggest that the spread of the virus, transmitted to humans from fruit bats, could be due to deforestation which has brought wildlife into direct contact with humans. It is spread from bodily fluids of infected bats and infected people, and in some strains from infected pigs.

“The symptoms last time were mostly convulsions, unconsciousness, headache and so on. This time patients showed viral pneumonia, cough among children, etcetera,” Dr Kumar told Open on the phone from Kozhikode. In the deadly 2018 Nipah outbreak in Kerala, 17 people had died and all of them had symptoms of encephalitis. It was Dr Kumar who found something very unusual about fever deaths in a family within a short span of time and intensified an investigation before he and his collaborators zeroed in on the Nipah virus. He gets the credit for first identifying the outbreak of Nipah virus in Kerala in the early morning on May 17, 2018, and then helped prevent the spread of the viral disease whose mortality rate is 89%.

The incubation period of the virus is estimated to be 4-14 days and in rare cases it may take as high as 21 days.

The people killed due to infection from the Nipah virus this time are two men aged 44 and 40. One died on August 30 and the other on September 12. “More samples are being sent for testing at the National Institute of Virology (NIV), Pune,” Kerala’s health minister Veena George said, adding that two labs in the state are also equipped enough to confirm Nipah virus infections.

The two deceased were admitted to local private hospitals in Kozhikode district due to fever. They had contact with each other. Nipah virus is a zoonotic virus transmitted from animals to humans. Studies have shown that although the virus is mainly transmitted first to humans through fruit bats, there are also cases when it has spread through pigs.

Dr Kumar said it is too early to confirm how infectious the virus outbreak is this year. He added that in India, except in the state of Jammu & Kashmir, instances of fruit bats causing the Nipah virus are common, although the reasons for it are not known. “It is not that the Nipah outbreak happens only in Kerala. It is that we are able to detect it here. There are chances that in other parts of the country, it is often not detected,” he says.

According to an advisory released by Kerala health minister Veena George, who said that health authorities had so far identified two areas in Kozhikode district for containment, people in the region have been asked to use masks and observe social distancing. Some other instructions are similar to those issued in the height of the Covid-19 pandemic that includes sanitising hands, use of N95 masks, regular washing of hands with soap, etcetera.

The two strains of the Nipah that is often found in the country are 1) the Bangladeshi strain that spreads from infected humans to humans, which is not highly infectious but with a high mortality rate and 2) the Malaysia strain. According to an academic paper published in the National Library of Medicine titled ‘Transmission Routes for Nipah Virus from Malaysia and Bangladesh’, “Nipah virus infection in humans is associated with a higher death rate in (the) Bangladesh (strain than in the) Malaysia (one). Additionally, Nipah virus spreads from person to person in Bangladesh but not in Malaysia.”

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