Explainer: Bangladesh strain of Nipah virus confirmed, what this means for Kerala

Scientists at the National Institute of Virology (NIV) in Pune have confirmed that the strains of the Nipah Virus found in the outbreak in Kerala are the same as the ones found in Bangladesh.

According to a report in the Times of India, scientists at the institute had studied throat swab samples obtained from an infected patient to reach this conclusion.

Speaking to TNM, Kerala Health Secretary Rajeev Sadanand said, “The strain of the virus is a 98.4% match with the virus that is typically found in Bangladesh.”

According to a study published by Scientific Reports Journal, the Nipah Virus is broadly grouped into one of two types either Malaysia strain (NiVm) or Bangladesh strain (NiVb) and both have been observed to be extremely fatal. During the 1998 outbreak in Malaysia, a unique strain of the virus was isolated from pigs, which were found to be the primary source of infection during that outbreak.

The Bangladesh strain ‘NiVb’ has been the cause of recurrent outbreaks between 2001 and 2015 in Bangladesh and Northeast India.

Differences in the strain

Studies have shown certain differences between the two strands of the virus. It has been noticed that NiVb has a shorter incubation period with a range of anywhere from 5 to 14 days and that patients infected with this strain typically present with severe respiratory related symptoms when compared to those who are affected by the NiVm strain of the virus. Those who have been affected by the Malaysian strain, however, often present with a period of contraction of the muscles known as myoclonus. Furthermore, it has been noted that the source of infection for this strain has been through pigs who have been called the ‘amplifying host,’ for the virus.

The Bangladesh strain of the virus has been known to cause repeated outbreaks though the source of the same has not always been confirmed, however fruit bats are the known hosts. It has been noted that contaminated fruits and date/palm sap have contributed to the spread of this virus. Human to human transmission has also been seen with the NiVb strain.

‘No new positive cases in Kerala’

Sadanand also said that the situation is stable at present and that ‘no new positive cases’ had been confirmed. “People are coming into the clinics and hospitals saying they feel like they have symptoms of Nipah but a lot of that can also be attributed to the fact that there is a fear amongst everyone. The first case was discovered around May 17 and with almost 13 days having passed, we are nearing the end of the incubation period,” said the Health Secretary.

Kerala Health Minister, KK Shailaja also reiterated that the situation was under control, but that the state is prepared should a setback occur. “A separate isolation ward will be set up at KCMH. Ventilator, X-ray, lab facilities will all be arranged at the ward. High-level alert will be put in place until June 10,” she said in a statement to the Deccan Chronicle.