Experts Remain Cautious on Nipah Virus Outbreak

  • by Molly Walker, Staff Writer, MedPage Today

India’s outbreak of Nipah virus should be monitored closely, especially if there is evidence that this is a respiratory-spread strain, said experts contacted by MedPage Today.

Nipah virus is currently on the World Health Organization (WHO) list of Blueprint priority diseases due to their public health risk and lack of countermeasures were they to cause an epidemic. This list also includes Zika and Ebola.

Reports from India’s The News Minute put the death toll from the current Nipah virus outbreak at 15 as of today — there are also two confirmed cases “under treatment,” and as of May 30, there have been eight more suspected cases.

Stephen Luby, MD, of Stanford University in Palo Alto, California, said the unease about Nipah virus centers around two factors: its high case fatality rate of 75%, and the fact that the virus can be transmitted from person-to-person.

“We don’t need to lose sleep immediately, because the person-to-person transmission tends to be inefficient,” Luby told MedPage Today — about 1 in 12 people transmit the virus. “Most people who get infected don’t pass it along, and because it’s inefficiently transmitted, you get short trains of transmission that tend to end on their own.”

But he added that there may be some cause for concern, because viruses can change, and some strains of Nipah are more likely to go into the respiratory tract than others.

Peter Hotez, MD, PhD, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston, said Nipah virus has generally produced fairly small outbreaks in the past: “When I think of global health infectious diseases, I tend to think they fall into two lines — neglected tropical diseases, which are chronic and debilitating, and the high-death-rate pathogens, like Ebola, Nipah, and SARS, that produce impressive outbreaks in terms of the number of people who die,” he told MedPage Today.

Hotez characterized Nipah virus as an “emerging infection” — one that researchers didn’t know about until an outbreak in Malaysia that was linked to pigs in 1998. Researchers traced the virus back to fruit bats, where the pigs were exposed to material dropped by the bats, followed by pig-to-pig, and eventually, pig-to-human transmission.

But this current outbreak in Kerala seems similar to the type of transmission seen in Bangladesh, Hotez said — where the originators are bats, but people are exposed through contact with palm tree sap contaminated by these bats.

“The virus strain in Bangladesh has more of a respiratory component, and we would be concerned about Nipah because of person-to-person respiratory transmission,” although all of this is still speculative, he said.

Luby said his main concern with the current outbreak would be for healthcare workers who may lack the supplies and institutional support in place to protect themselves from saliva and other secretions.

“If those systems are not safe, a variant of Nipah can go into a healthcare system and spread wildly. It emphasizes the importance of precautions in dealing with ill patients, and the importance of reaching out to folks outside of high-income countries to ensure patient and healthcare worker safety.”

Hotez also pointed out that there is not yet a vaccine against Nipah virus, although some progress is being made on that front. For example, the Coalition for Epidemic Preparedness Innovations announced on Wednesday that it awarded a grant of up to $25 million to Profectus BioSciences and Emergent BioSolutions for the development of a Nipah virus vaccine.

Luby also cited the potential use of a monoclonal antibody, M102.4, which showed promise against the virus in certain types of monkeys, but treatment must be given early. There is lack of diagnostic testing and antivirals against Nipah virus, but the reason is that there hasn’t been a lot of work done with the virus yet, he added.

Hotez pointed out that the WHO has yet to declare the current outbreak a Public Health Emergency of International Concern, but that this outbreak should continue to be watched closely: “If this virus is showing evidence of human-to-human transmission, like the Bangladesh strain, we’re going to have to take this very seriously.”

Source: Medpage Today


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