Nipah virus — Unbound and unpredictable

August 7, 2019 0 By S Harachand

When the NiV outbreak occurred in Kerala, it was confirmed within 12 hours of notification, and that too, with no help from outside the country. This was made possible by the quick action of the Virus Research and Diagnostic Laboratory (VRDL) and a strong public health response launched by the Department of Health and Family Welfare, Government of Kerala, which also involved the private hospital sector. The Integrated Disease Surveillance Programme of the National Centre for Disease Control, the Indian Council of Medical Research (ICMR)-VRDL scheme, and the Global Health Security Agenda in India scheme and the Global Health Security Agenda in India helped this rapid diagnosis and response. The spread of the outbreak was also contained by a swift public health response by the state and the Ministry of Health and Family Welfare, Government of India, ICMR and its institutes.

Prompt intervention by the state government, smooth coordination with the research lab network and above all, an instantaneous response and efficient management by a team of doctors with hands-on experience from last year’s outbreak was able to limit a probable outbreak in 2019 to a single incident.

Certainly, public health authorities deserve due credits for working as an agile, well-oiled system to obviate the possibility of a catastrophic health crisis in a thickly populated state. Even in 2018, Kerala was able to contain the infection from spreading wide, with the best possible effort in the instance. This was despite the fact that the people involved were all new to NiV. This year too, the state was on top of the situation when NiV raised its hood for the second time. But success should not give way to complacency or the belief that the threat is over and there is no need to worry anymore, warn sceptics.

This deadly pathogen showed up in 2018, and went underground only to resurface again at the exact time of the subsequent year to confirm that NiV is now endemic to the region.

Virologists say that they had alerted the authorities about the chances of a comeback, as NiV follows a seasonal pattern in outbreaks.

”An NiV infection is usually self-limiting. But we are yet to fully understand the virology of this somewhat newly emerged organism,” comments Dr Anoop Kumar AS, Chief of Critical Care Medicine at Baby Memorial Hospital, Kozhikode.

Strain to strain variations are observed in NiV. Genetic sequencing has already confirmed that the NiV strains circulating in Bangladesh and India (NiV-B) are different from the strains identified in Malaysia and Singapore (NiV-M).

Human-to-human transmission, as discussed, is more common with NiV B than the Malaysian strain. Lineage diversity needs to be taken into consideration in order to identify strains specific to a region, as well as for the detection of all circulating strains.

According to studies the reproductive number of NiV is less than 0.5 and hence it cannot sustain transmission. This means that it is unlikely to cause a major outbreak in the current scenario. However, the epidemiology can change when the NiV is introduced to different settings such as urban slums or overcrowded hospitals. One of the real concern about the virus is whether it gains sustained human to human transmission capability which can result in sustained and catastrophic outbreak as we have seen with Ebola in west Africa and DRC Congo.