A recent Nipah virus outbreak in Kerala, India, was halted due to improved detection capabilities. G. Arunkumar tells the story of his involvement.
Julie’s Biggest Takeaways:
Because bats are the normal reservoir, Nipah virus outbreaks appear to be seasonal, with an increase in cases coinciding with the spring, when the bat reproduction season is.
Once a person is infected through direct contact with the virus, the virus is transmitted person-to-person through respiratory droplets.
Family clusters combined with the right incubation time acted as a clue that a Nipah virus outbreak had begun.
Molecular tests improved virus detection during the 2018 Nipah outbreak because patients presented symptoms within a few days, which was too short for them to have developed antibodies. Molecular tests allowed identification of infected patients within days. Previous outbreaks have taken weeks to months, or even years, to identify the infectious virus.
A single crossover event in the recent Nipah outbreak led to person-to-person transmission within the 22 additional individuals. Hospital infection control practices are important to reduce transmission to healthcare workers and hospital attendants.
“Most of the Nipah outbreaks, you find a lot of hospital transmission from the infected patient to healthcare workers, the other patients in the ward as well as the patient attendants.”
“The only virus that can cause encephalitis in a family cluster is Nipah. With other encephalitis viruses like herpes or Japanese encephalitis virus, you don’t see family clusters.”
“Nipah virus is a level 4 pathogen, so the cultivation can be only done in a level 4 laboratory. But molecular tests allow you to test for it at a lower level laboratory, such as a BSL-3 lab, because you inactivate the virus. You are only focusing on RNA. The risk can be reduced.”
“When you use serological diagnosis, the antibodies are detectable only after 8-10 days after onset of illness. Nipah is a very, very acute, serious fatal disease. Many people may die before they develop antibody. So we need to use a combination of real-time PCR and antibody.”
“This is the first time in the history of Nipah that the diagnosis was done in country. All the previous diagnoses were done at CDC Atlanta.”
Links for This Episode:
- Department of Virus Research at Manipal Academy of Higher Education
- Journal of Clinical Microbiology Review on Nipah virus
- HOM Tidbit: NPR piece interviewing K. B. Chua and others
- HOM Tidbit: Science article first describing Nipah virus
- MTM Listener Survey
History of Microbiology Tidbit:
In today’s History of Microbiology tidbit, I want to highlight the scientist who first identified Nipah virus. Of course, discovery was really a team effort, and if you read the Science paper that first identified Nipah, there’s something like 20 authors. But the lead author, K. B. Chua, is Kaw Bing Chua, a medical microbiologist who was a student at the University of Malaya in Malaysia during the time of the first Nipah outbreak.
During a new infectious disease outbreak, the source of infection, including the route of transmission, is a mystery. One first suspect is mosquitos, which can transmit many different types of microbes in their bites. But Chua, along with neurologist C.T. Tan who was treating Nipah patients at the University, both realized there was a clue in the patient demographics: none of the sick were muslim. About two thirds of malaysians are muslim, but none of the nipah patients were. Muslims avoid pigs, not only by not eating pork, but also by not handling pigs. This was the first clue that led Chua to investigate pig samples, and find the virus in pig respiratory tracts. From here, the scientific team went on to show that Nipah virus can infect a number of animals, including dogs and cats as well as fruit bats, as we discussed early in the show.