In total, we live with about 850,000 viruses with the capacity to infect humans. And these are just the known ones, as there are still many to be discovered, which means that new vaccines must be developed for many of them, e.g. The Nipah virus that is currently causing an outbreak in India.
The Nipah virus was first discovered more than two decades ago after an outbreak among pig farmers in Malaysia. Within months it had spread to Singapore through infected pigs. The outbreak caused nearly 300 cases and more than 100 deaths.
Since then, no other outbreaks have been reported … in Malaysia. But in 2001, the virus appeared in Bangladesh and India, where it has continued to break out at regular intervals. In Bangladesh, they occur almost every year, and studies have linked infections to consumption of fermented date palm juice contaminated with bat urine. For now It is not clear exactly when and how the virus It went from bats to humans in the current outbreak in Kerala, but this is one of the most important assets in understanding the mechanisms of transmission and infection and thus being able to treat them.
The Nipah outbreak is the fourth to hit Kerala (India) in five years; the previous one was in 2021. Although these outbreaks typically affect a relatively small geographic area, they can be deadly, and some scientists worry that further spread among humans could make the virus more contagious. Your mortality It is between 40% and 75% depending on the strainRajib Ausraful Islam, a doctor specializing in bat-borne pathogens, says: “Every outbreak is a concern as it gives the pathogen a chance to change itself.”
The virus can cause fever, vomiting, breathing problems and inflammation of the brain. That transmitted mainly by fruit bats, but in addition to humans it can also infect domestic animals such as pigs. It is transmitted by contact with bodily fluids from infected animals or humans, and there are still no approved vaccines or treatments.
In this latest outbreak, the bat-borne Nipah virus has infected six people (two of whom have died) since it emerged in late August. More than 700 people were tested for infection over the past week. State authorities schools, offices and public transport networks are closed.
The problem for experts is that the strain circulating in India and Bangladesh is different from that which arose in Malaysia: While the latter spread from animals to humans, there was little human-to-human transmission, but the version behind the latest outbreak in Kerala can be transmitted from person to person and is much more deadly.
The kinder side of this virus (or at least the less urgent) is It is not easily transmitted between people like other animal-borne infections, making it less likely to spread across national borders, says Danielle Anderson, a virologist at the Royal Melbourne Hospital in Australia. A study published in 2019 of nearly 250 cases of Nipah virus in Bangladesh over 14 years found that about a third of human infections were transmitted to another person, but “I wouldn’t expect it to spread globally,” adds Anderson. “Nothing to the extent we’ve seen with the COVID-19 pandemic.”
The high mortality rate of the virus also makes it less likely to spread quickly through the population. According to Christopher Broder, a specialist in emerging infectious diseases, “it is not in the best interest of the virus to kill everyone it infects. The strain is circulating in Kerala hasn’t changed much since it first appeared more than two decades ago in Bangladesh, although future outbreaks could be larger if it mutates into a milder but more infectious strain. “It is also likely that yet-to-be-discovered variants are already circulating.”
An important step in preventing outbreaks of Nipah and other bat-borne viruses is develop better ways of managing wildlife who live close to the communities. Studies on Hendra virus, another bat-borne pathogen closely related to Nipah, suggest that infected bats shed more virus particles when stressed, increasing the chance of the disease spreading to livestock and then to humans.
One approach that could go a long way toward preventing future outbreaks is to restore forested areas to improve bat habitat, which would provide them with a more reliable food source and reduce the risk of overflow.
Another way to reduce the risk of new outbreaks caused by bats is to “plant more trees that produce fruits that are tasty to bats but not to humans – concludes Islam -. This could help prevent infected bats from contaminating food. “We must learn to live safely with bats.”