As the Nipah Virus is in the news Crystal’s Uncle David Waltner-Toews recently shared a excerpt from his Book On Pandemics (Greystone Press, 2000) on his blog. I thought I would re-blog here as well since there have been a lot of questions and concerns about the Nipah Virus especially as we come into the Lunar New Year.
Jan 28, 2026: Nipah Virus In India: What Is Actually Going On? Timeline Explained
India has confirmed two Nipah virus cases in West Bengal since December, with health authorities containing the situation amid misinformation and heightened airport screenings in parts of Asia.
Nipah Virus – From my Book On Pandemics (Greystone Press, 2000). David Waltner-Toews.
In late 1998 reports came out of Malaysia about an outbreak of Japanese encephalitis, caused by a virus related to West Nile virus and transmitted by mosquitoes. Since Japanese encephalitis is endemic in that part of the world, these reports were interesting but not terribly surprising. By December, eleven people had fallen ill and four had died; farms were fogged with insecticides, people were vaccinated, and the outbreak was declared over. By February 1999 there were twenty-five cases, with thirteen deaths; in mid-March, it was reported that ninety-eight people had fallen ill, forty-four of them fatally, within a three-day period. Thousands of homes and pig farms had been fogged with insecticides and thousands of people vaccinated with a Japanese encephalitis vaccine. Later the same month, there were reports that abattoir workers in Singapore had come down with encephalitis after slaughtering pigs from Malaysia. Japanese encephalitis is transmitted by mosquitoes. How could this be Japanese encephalitis? Was this, in fact, not Japanese encephalitis but a new disease?
Shortly afterward, the disease was being described as “Hendra encephalitis,” and later, because it first appeared in the village of Sungai-Nipah, as Nipah virus encephalitis. A new disease, characterized by fever and coughing followed by drowsiness and sometimes a coma, seemed to have come out of nowhere. It seemed to start in pigs and spread from there to dogs and people; older animals were more likely to become severely ill, with unsteady gait and frothing at the mouth. Scientists and investigators from around the world joined forces to investigate.
Reports from the Centers for Disease Control and Prevention in Atlanta sounded both excited and anxious. This virus had never been seen before. No one knew how it was transmitted or what it was capable of doing. Scientists wore gowns, gloves, and battery-operated respirators as they slogged their way through the pig farms at the center of the epidemic.
Even as the scientific investigation proceeded, the Malaysian army came in. More than a million pigs were slaughtered and buried. By the time the epidemic was over, in May 1999, 265 people from Perak, Negeri Sembilan, and Selangor states in Malaysia—mostly workers on pig farms—had fallen ill with encephalitis; more than a hundred died.
Where had the disease come from? Because pteropid bats (flying foxes) were suspected of being the main reservoirs of the related Australian Hendra virus, investigators pursued that avenue as one of several leads. Flying foxes (Pteropus spp.), which have a brain structure similar to that of primates and flying lemurs, are an interesting bunch. They are megabats, classified as megachiroptera to differentiate them (as if we couldn’t tell) from microchiroptera, the microbats. Megabats have keen eyesight and roost in trees rather than in caves or houses. Some of the males sing in courtship. The females have single babies and nurse them at breasts. They eat fruit and nectar and are important for the survival and spread of flowering and fruiting plants in Africa, Asia, and Oceania.
Bats of various species are home to a variety of interesting viruses, including Hendra, Nipah, and, as we subsequently discovered, SARS-CoV and SARS-CoV-2, as well as those that cause Ebola and Marburg hemorrhagic fevers in Africa. Not only that, but a group of researchers from California State University have proposed that the Chamorro people of Guam, who have one of the world’s highest rates of a fatal, progressive paralysis, amyotrophic lateral sclerosis, better known as als, or Lou Gehrig’s disease, are being poisoned by a neurotoxin. This toxin, which comes the fruit of the palm-like cycad Cycas micronesica, is concentrated in, among other places, flying foxes, which the Chamorro cook up in coconut milk. Megabats are important for the ecological sustainability of the planet. They are gregarious, and they are excellent social role models for children. They apparently taste pretty good, too, and are sold as food in many east Asian markets. And they are potentially deadly and not to be messed with. A lot like us, then.
But how would the virus get from fruit-eating bats to pigs and people working on pig farms? And why in 1998–99? A plausible story that has emerged from the investigations brings together a complex set of interactions. Sadly, the story is both messy and increasingly common.
The El Niño–Southern Oscillation (enso) phenomenon is a huge natural cycle of oceanic and air currents across the southern Pacific. It was called El Niño by the Peruvians because it arrives just after Christmas, El Niño being the Spanish term for the Christ child. enso has been related to a wide variety of natural events, from the upwelling (and disappearance) of anchovies in Peru to monsoon rains and droughts in South and eastern Asia and all the way over to the east coast of Africa.
Scientists think that the enso cycles have been getting more frequent and more severe, probably as the result of human-induced climate change. The 1997–98 enso was the worst on record to that date, resulting in a major drought through Southeast Asia. Even as the drought deepened, Indonesian forestry companies slashed through the forests of the area with wild abandon, and desperate Indonesian and Malaysian farmers set fires to clear land. That year, millions of acres burned out of control, and a haze of smoke covered the region, casting the landscape into shadow. Because the sun was blocked by the smoke, the forests and scrublands that were not directly destroyed by the fires suffered huge drops in a variety of crops, including many flowering and fruiting plants. This is where we get back to the fruit bats. With forests disappearing and fruiting and flowering plants deeply depressed in the smoky haze, the flying foxes were running out of options.
In the late 1980s, Malaysia (a Muslim country) had dramatically increased pig production to meet the needs of the Chinese in Southeast Asia, especially in Singapore, which was phasing out farming because it was running out of land. The Malaysians, being conscientious about land use efficiency, grew mango trees on their pig farms. In fact, mango production expanded at about the same rate as pig production in the 1980s and 1990s.
The Malaysians also let the pigs go into outside enclosures for fresh air. Guess what. The fruit bats found the fruit trees. They pooped into the open pig pens and dropped partially eaten fruits. The pigs, which will eat anything, ate everything; the virus came along for the ride. The viruses liked the pigs. Only a few pigs got sick, but the virus had a multiplicative heyday. The farmers picked up the virus from the pigs. Only a mass slaughter of pigs stopped the epidemic.
In several years following the epidemic, there were outbreaks of encephalitis, clinically appearing as fever, headaches, and “altered levels of consciousness,” in Bangladesh and West Bengal State in India. In these countries, people who climbed date palms and drank raw palm juice were getting the disease. The palm juice was collected in open-topped clay pots. Fruit bats, feeding in the same trees, had apparently dropped half-eaten bits of fruit, as well as, possibly, feces, onto the pots. In this case the preventive measures were simpler and less traumatic than in Malaysia: put cloth covers on the pots.