Posted on 04TH JUL 2018
tagged Nipah Encephalitis, India

A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases

Date: Tue 3 Jul 2018
Source: MediBulletin [edited]

Putting to rest suspense about the source of the Nipah virus infections in Kerala, scientists from the Indian Council of Medical Research have now found the virus in bats that were caught from the affected areas. At least 17 people died of Nipah infection in Mallapuram and Kozhikode districts of Kerala over April and May [2018].

While the 1st batch of bats caught from the well in Kozhikode in the house from where the 1st case was reported, had tested negative; of the 2nd batch of 52 fruit bats, 19.2 percent were found to carry the virus. The findings will be published in The Lancet. Health minister J P Nadda was informed about the findings in a meeting last week.

In the meeting, scientists from ICMR and public health officials also told the minister that circumstances have now improved enough for the state to be declared Nipah free. The incubation period of Nipah is 5 to 14 days. The last case was in May [2018] and now that 2 incubation periods have elapsed without any fresh cases, the specter of the dreaded disease seems to be finally receding.

Communicated by:

[It is good to learn that there have been no additional cases of Nipah virus infection in Kerala. As was mentioned earlier, it is not surprising that the bats taken from the well were negative for the virus. Giant fruit bats (flying foxes genus _Pteropus_), the reservoir of Nipah virus in Bangladesh and Malaysia, do not roost in wells. They roost in tree tops. The species sampled in the 2nd batch of bats was not mentioned, but were likely flying foxes. It is fortunate that virus positive bats were found in this 2nd sampling. As commented earlier, bats "may only be infectious for a week or 2, and then they clear the virus and they're no longer infectious," said Jonathan Epstein, a veterinarian and epidemiologist at EcoHealth Alliance, New York, who has, for over a decade, studied Nipah outbreaks and the bats that cause them, in Malaysia, India and Bangladesh. "That's why these outbreaks are relatively rare events, given the fact that these bats are so abundant and so common but very few of them are ever actually shedding virus at a given time."

Epstein and others conducted an experimental study of _Pteropus_ bats in 2011 and found that the time window in which the bats are capable of passing on the infection to other animals or humans is quite small. In fact, the virus can't be found in experimentally infected bats after a few weeks. The few bats in an infected population that could be shedding the virus may be doing so in low quantities and for a short duration.

"Finding that bats don't have Nipah virus at the time of sampling certainly doesn't mean that it didn't come from those bats, particularly _P. medius_," Epstein said. "The overwhelming abundance of evidence really shows that this bat is the reservoir for Nipah virus on the subcontinent in Bangladesh and in India." - Mod.TY

Maps of India can be accessed at:

HealthMap/ProMED map available at:
Kerala State, India:]

See Also
Nipah virus - India (13): (KL) 20180611.5851326
Nipah virus - India (12) 20180603.5836554
Nipah virus - India (11): (KL) 20180602.5835342
Nipah virus - India (10): (KL) 20180602.5833137
Nipah virus - India (09): (WB ex KL) susp. 20180530.5829184
Nipah virus - India (08): (KR ex KL) susp. 20180529.5826769
Nipah virus - India (07) 20180528.5822566
Nipah virus - India (06): (KL,KA) 20180526.5819777
Nipah virus - India (05): (KL,TG) 20180525.5817917
Nipah virus - India (04): (KL, KA) 20180524.5815473
Nipah virus - India (03): (KL) conf. 20180522.5812214
Nipah virus - India (02): (KL) conf 20180521.5809003
Nipah virus - India: (KL) susp 20180521.5807513
Nipah virus, fatal - India (West Bengal) (02) 20070511.1514
Nipah virus, fatal - India (West Bengal) 20070508.1484
Undiagnosed deaths - Bangladesh, India (04) 20070504.1451