MOSCOW, September 25, Salma Sultanova. There is another outbreak of the Nipah virus in India. In the southern state of Kerala, six people were infected and two died. Several schools, offices, and public transport route networks were closed. Some scientists fear that the active spread of the pathogen among people will lead to greater infectiousness. What is known about the virus and whether it will spread beyond Asia — in the material .
Outbreaks of the Nipah virus have become more frequent
This is the fifth outbreak to hit Kerala in the last five years. The previous one was in 2021, Nature reports. According to Rospotrebnadzor, since May, 26 people with suspected infection have been under observation in medical institutions. The Indian government has taken control of the situation, and neighboring states do not want Kerala residents to visit their territory.
This is not a completely new virus for us. Nipah was first recorded in Malaysia in 1998. Then from 238 to 265 people fell ill. The death toll ranged from 105 to 109, indicating a high mortality rate. This was confirmed by subsequent epidemics.
In March 1999, Nipah struck Singapore. Of the 11 patients, one died. The outbreak ended with a ban on the import of pigs from Malaysia.
In Bangladesh, outbreaks of the virus occurred almost every year from 2001 to 2013, especially during the winter months. The mortality rate during the first epidemic in 2001 was 69 percent, and in 2013 it rose to 83 percent. In total, from April 2001 to March 31, 2012, 209 people became infected, 161 died.
India, like Bangladesh, has also had outbreaks, although not as frequently. The first time was in West Bengal in 2001. Of the 66 infected, 45 died. A second outbreak occurred in the same region in 2007, when Nipah was confirmed in five people. Everyone died. In May 2018, 18 cases were reported in Kerala. The patients suffered from acute respiratory syndrome and encephalitis. 17 people died, the mortality rate from Nipah then exceeded 90 percent. In 2021, a 12-year-old child fell ill in Kerala, also with a fatal outcome.
In 2014, the virus reached the Philippines. The disease was confirmed in 17 people, nine died.
According to the head of Rospotrebnadzor Anna Popova, Russia has a test system for detecting the Nipah virus, but not a single case has been registered yet. The agency is doing everything to prevent infection from entering the country.
What is the Nipah virus
Nipah (NiV) is an enveloped pleomorphic virus whose genome consists of single-stranded negative-sense RNA. Viral RNA encodes six structural proteins: nucleocapsid, phosphoprotein, matrix protein, fusion protein, glycoprotein and RNA polymerase. The glycoprotein and hybrid protein are located throughout the envelope of the virus; it is with their help that it attaches to the host cell and then enters it.
“Nipah is a classic zoonosis, that is, an infection transmitted from animals to humans. Ebola and coronavirus belong to the same group. Zoonoses have different mortality rates, but in Nipah it is very high — from 45 to 75 percent. Now this virus is attracting a lot of attention «the attention of virologists and epidemiologists, since it has been clearly proven that it can be transmitted from person to person. The spread can have serious consequences,» says Olga Karpova, Doctor of Biological Sciences, Professor, Head of the Department of Virology, Faculty of Biology, Moscow State University named after M.V. Lomonosov.
Infection caused by the virus can damage the brain, lungs, heart, kidneys and spleen. In humans, it occurs both asymptomatically and in acute respiratory form. In severe cases, there is a risk of developing fatal encephalitis. The first signs are fever, headache, myalgia (muscle pain), vomiting and discomfort in the throat. Then — dizziness, drowsiness, altered consciousness and neurological signs indicating acute encephalitis. Sometimes atypical pneumonia and acute respiratory failure occur.
The incubation period is from four to 21 days. However, it can be longer. For example, during the Nipah outbreak in Malaysia, the disease made itself felt after two months. An infected person is expected to remain contagious for 21 days after the onset of symptoms.
How is Nipah transmitted and how contagious is it
“The reservoir of this virus is bats. The infection is carried by all the fluids they secrete: blood, urine, saliva. Often these secretions end up on fruits or in palm juice. A person who eats them becomes infected. There is also a transmission link between bats, for example, pigs. The infection can spread to a person from them. And people are already infecting each other. As you can see, there are a lot of ways of spread,» explains Professor Karpova.
Nipah's natural reservoirs are frugivorous bats of the family Pteropodidae — in particular, species belonging to the genus Pteropus. Apparently, the infection does not harm the animals themselves. The transmission links also vary. For example, while the outbreaks in Malaysia and Singapore were linked to pigs, in the Philippines it was horses. Infection occurs through eating unprocessed meat from infected animals or contact with their secretions. You can become infected from a person through contact with their fluids: droplets from the respiratory tract, blood, urine.
«No one can answer how contagious Nipah is. So far this is a fairly local story. If an outbreak occurs somewhere, it is more likely due to population migration rather than the virus. The degree of danger of the virus for people is assessed by the R0 index. For example, in rubella it is 16-18, and for coronavirus it is about 2. The R0 index of Nipah is not yet known,» says the virologist.
Olga Karpova adds that there is a certain tendency of spread — so far within one area. However, given the high migration flows, the situation should be closely monitored.
According to Daniel Anderson, a virologist at the Royal Melbourne Hospital in Australia, the virus does not spread as easily between people as other animal-borne infections. This reduces the likelihood of it going outside India. A 2019 study in Bangladesh showed that out of 248 patients who became ill between 2001 and 2014, only 82 became infected from humans.
«I don't think it's going to spread around the world. It's not going to be anything like what we've seen with COVID-19,» Anderson continued.
Echoes an expert in emerging infectious diseases at the Uniformed Services University School of Medicine in Bethesda. Christopher Broder.
«The high mortality rate of the virus makes it impossible for it to spread quickly through the population. Killing everyone it infects is not in Nipah's interest. The strain circulating in Kerala has not changed much since it first appeared more than two decades ago in Bangladesh. Future outbreaks could The only way to get bigger is if it mutates into a milder but more contagious strain, and there are likely variants already circulating that we haven't detected yet.»
How to protect yourself from infection
The vaccine for Nipah has not yet been created. There is only the option of palliative care — that is, aimed at alleviating symptoms.
«Patients are transferred to therapy, nothing more can be done. They lower the temperature, prescribe plenty of fluids, support the cardiac system — everything is as with any viral infection» , says Olga Karpova.
According to the expert, the vaccine should be created as soon as possible. Recombinant and genetically engineered vaccines are the best way to combat the disease. They are cheaper to produce and transport, do not contain the virus itself, and are quite safe.
Increasing awareness of risk factors can also reduce the spread of Nipah. The European Center for Disease Prevention and Control advises actively identifying new cases, tracing contacts of infected people, maintaining quarantine, avoiding close contact, using protective equipment and remembering good hygiene. Control measures must also be applied to animal vectors. Thus, the slaughter of infected cattle helped stop the outbreak that raged in Malaysia. In addition, it is necessary to regularly prevent infections in animals susceptible to the virus and protect fruit trees from them.