#17,266
Although novel influenza and coronaviruses top our list of pandemic concerns there are lesser threats - like Monkeypox, Lassa Fever, and Nipah - that are regarded as having either epidemic, or potentially even pandemic, potential.
Among these, Nipah - a bat borne henipavirus related to both Australia's Hendra virus and the recently discovered Langya virus in China - has the highest fatality rate and is often listed as a virus of concern.
- In 2015's Blue Ribbon Study Panel Report on Biodefense a bi-partisan panel described a fictional biological attack on Washington D.C. using a genetically engineered Nipah virus as part of their presentation.
- Five years ago, in the Johns Hopkins Clade X exercise, a genetically altered Nipah virus (spliced onto a parainfluenza backbone) was the cause of their fictional pandemic.
- Also in 2018, in WHO List Of Blueprint Priority Diseases, we saw Nipah and Henipaviral diseases listed among the 8 viral threats in need of urgent accelerated research and development.
Since then, we've seen sporadic outbreaks in Bangladesh and India. Unlike COVID-19 - which appears to kill roughly 1% of those infected, human infection with the Nipah virus is fatal between 70% and 90% of the time.
Nipah often finds its way into humans via the consumption of raw date juice which can be contaminated by bat saliva and feces. Collection of date palm juice is a seasonal activity (December - May) in Bangladesh, which not surprisingly, is the same time period that defines their Nipah season.
Over the past two weeks Bangladesh has reported 8 Nipah cases (5 fatal) (see Lisa Schnirring's CIDRAP report Bangladesh reports more Nipah virus cases).
In the 2013 paper The pandemic potential of Nipah virus by Stephen P. Luby, the author wrote (bolding mine):
Characteristics of Nipah virus that increase its risk of becoming a global pandemic include: humans are already susceptible; many strains are capable of limited person-to-person transmission; as an RNA virus, it has an exceptionally high rate of mutation: and that if a human-adapted strain were to infect communities in South Asia, high population densities and global interconnectedness would rapidly spread the infection.While the Nipah outbreaks we've seen have only demonstrated limited human-to-human transmission, each outbreak provides the virus with additional opportunities to better adapt to humans, and potentially increase its threat.
In addition to bats and humans - other mammals have been infected in the wild (horses, pigs, and dogs) - and many others have been experimentally infected in the lab (including guinea pigs, hamsters, ferrets, squirrel monkeys, and African green monkeys).
All of which brings us to a new Dispatch, published in the CDC's EID Journal, that describes the detection of NiV antibodies in cattle, dogs, and cats in proximity to known outbreaks in humans. First the abstract and a few excerpts from the dispatch, after which I'll return with a bit more.
Volume 29, Number 2—February 2023
Dispatch
Nipah Virus Exposure in Domestic and Peridomestic Animals Living in Human Outbreak Sites, Bangladesh, 2013–2015
On This Page
Ausraful Islam, Deborah L. Cannon, Mohammed Ziaur Rahman, Salah Uddin Khan, Jonathan H. Epstein, Peter Daszak, Stephen P. Luby, Joel M. Montgomery, John D. Klena, and Emily S. Gurley
Abstract
Spillovers of Nipah virus (NiV) from Pteropus bats to humans occurs frequently in Bangladesh, but the risk for spillover into other animals is poorly understood. We detected NiV antibodies in cattle, dogs, and cats from 6 sites where spillover human NiV infection cases occurred during 2013–2015.
Henipaviruses are batborne zoonoses that have caused fatal neurologic and respiratory disease outbreaks in humans, horses, and pigs. In Bangladesh, the Indian flying fox (Pteropus medius) is the known natural reservoir for Nipah virus (NiV). NiV causes annual outbreaks in humans in Bangladesh, where the primary mode of spillover is through consumption of date palm sap contaminated by P. medius bats (1); NiV infection is a particular concern for public health because of the high case-fatality ratio and the risk for person-to-person transmission (2).
Domestic and peridomestic animals have been important intermediate hosts for zoonotic henipavirus transmission in outbreaks occurring in Australia, Malaysia, and the Philippines (3,4). One cross-sectional study suggested possible exposure of livestock to henipaviruses in Bangladesh (5). Three instances in which animal contact was associated with human NiV infections in Bangladesh have been reported (1,6,7), although little is known about the transmission mechanisms of henipaviruses into livestock and peridomestic animals in Bangladesh. Our study aimed to detect prior NiV infection among livestock and peridomestic animals living in proximity to humans with spillover cases and identify possible exposure pathways in Bangladesh.
(SNIP)
Conclusions
Our study found that a small proportion of domestic animals (e.g., cattle and goats) had evidence of NiV antibodies, whereas evidence of antibodies were more common in peridomestic animals (e.g., cats and dogs). Because peridomestic dogs and cats roam around freely, they may have scavenged bat carcasses or placentas underneath the roost without knowledge of the owners. Previous studies have described henipavirus infection among dogs and cats in other countries (4,11,15).
Characterizing the risk factors for infection and the potential role of domestic animals as intermediate or amplifying hosts in Bangladesh would provide a more complete understanding of the ecology of NiV in Bangladesh. In addition, to avoid potential spillover, owners of domestic animals could be advised to not feed them dropped fruit.
Dr. Islam is a veterinarian at icddr,b (formerly known as the International Centre for Diarrhoeal Disease Research, Bangladesh). His primary research interests include zoonotic pathogens.
Enhancing preparation for large Nipah outbreaks beyond Bangladesh: Preventing a tragedy like Ebola in West Africa
Halsie Donaldson, Daniel Lucey
Highlights
- Nipah epidemiology has differed in Malaysia, Bangladesh, and the Philippines.
- Beyond Bangladesh, there is a need to enhance preparedness for large Nipah outbreaks.
- Nipah epidemics beyond South Asia should be prevented to avoid a tragedy like Ebola in West Africa.
Abstract
The Nipah virus has been transmitted from person-to-person via close contact in non-urban parts of India (including Kerala May 2018), Bangladesh, and the Philippines. It can cause encephalitis and pneumonia, and has a high case fatality rate.
Nipah is a One Health zoonotic infectious disease linked to fruit bats, and sometimes pigs or horses. We advocate anticipating and preparing for urban and larger rural outbreaks of Nipah.
While a Nipah epidemic is probably the worst-case scenario, and will hopefully never come to pass, there are plenty of other pandemic contenders out there (MERS-CoV, Lassa Fever, HPAI H5N6, Virus X, etc.) that carry a much greater fatality rate than COVID, and would give humanity a very bad time indeed.
As we stumble towards the `official' end of the COVID pandemic (hopefully the virus gets the memo), the next global health crisis may already be simmering in a bat, rat, or cat somewhere in the world, waiting for an opportunity to begin a its world tour.
And when that happens, we'd better be more prepared than we were when SARS-CoV-2 emerged. Because the next one could be far worse.
