A hangout for bats, tourists and now virus sleuths
Scientists search caves at Thai national park for species believed to be linked to COVID-19
Many virologists believe the horseshoe bat, an avid bug eater, may be linked to the coronavirus. And a Thai national park report identified a species of horseshoe bat in the caves.
The area around the caves, Photharam district in Ratchaburi province, has tied its fortunes to bats — drawing tourists, fertilizer companies and, most important of late, chiropterologists, scientists who study flying mammals.
At the local economy’s tiny, fluttering heart — some bats can vary their heart rate by 800 beats per minute — is Khao Chong Phran Temple, which owns the limestone grottoes where the bats shelter during the day. In one cave alone, there are 3 million bats from 10 different species.
Nearly one-quarter of the world’s mammal species are bats, and their ability to fly while hosting a petri dish of viruses makes them both zoological marvels and efficient vectors of disease. Infectious diseases that are believed to have emerged from bats in recent decades include coronaviruses that cause severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), along with other viruses like Nipah, Hendra and Ebola.
Most of these viruses were transferred from bats to an intermediate host, like a palm civet or camel, before making their way to humans.
Although the coronavirus that causes COVID-19, which came to public attention in late 2019, has not been conclusively traced to bats, in Yunnan province in southwestern China, a researcher found evidence in horseshoe bats of a virus that closely resembles it. Horseshoe bat droppings from Cambodia have also shown some linkages. And the same bat family was the natural reservoir for the SARS coronavirus.
The discovery of the possible connection between horseshoe bats and the coronavirus linked to COVID-19 prompted Dr. Supaporn Watcharaprueksadee, deputy chief of the Center for Emerging Infectious Disease of Thailand and a specialist in bat-borne viruses, to investigate whether bats in Thailand may share a similar viral load.
Supaporn said her team has found no trace of a coronavirus similar to the one that causes COVID-19 in the bats of Khao Chong Phran Temple, although other coronaviruses have been discovered there. Nor has she found any horseshoe bats there.
Testing of human residents in and around Khao Chong Phran, including of guano collectors who have spent decades in proximity with bats, turned up no antibody evidence of the virus, either.
Although Thailand was the first country outside of China to confirm a case of COVID-19 — in a Chinese tourist visiting in early January — the nation had appeared since May to have all but strangled local transmission. Thais have been generally vigilant about wearing face masks, and the country’s borders were ordered closed to prevent the virus from arriving from abroad.
But in recent weeks, the coronavirus has begun spreading across the country after first being identified in migrant communities working along the porous border with Myanmar. Thailand went from no cases of local transmission in months to reporting hundreds of cases a day in late December and January.
Xenophobia has spiked, along with chiroptophobia, the fear of bats.
In the view of the guano collectors of Khao Chong Phran, which is not far from the frontier with Myanmar, the anxiety caused by bats is overblown. There are 17 species of bats in the area, and only two are fruit-eating bats tied with the spread of disease, they say.
“Even before my grandfather’s generation, we collected guano from the caves,” said Jaew Yemcem, 65, resting on the temple grounds with her bare feet nestled in soft mounds of bat excrement. “They were fine, and we are fine.”