Covid-19 arrived in Cambodia a year ago, on Jan. 23, when a Chinese national flew in from Wuhan, the city where the illness was first detected, and soon fell sick with a fever. A P.C.R. test came back positive.
For Cambodia, a developing country with a rudimentary health care system and multiple direct flights from Wuhan, the new disease presented an especially high risk.
Dr. Jessica Manning, a public health researcher with the National Institute of Allergy and Infectious Diseases who had been working in Cambodia for years, also saw an opportunity: helping the country join the global effort to watch for new diseases.
In those early days of Covid-19, researchers did not know how accurate the P.C.R. tests were or whether the virus was spawning new strains with potentially different properties. The Cambodian report helped confirm the accuracy of the P.C.R. test, and it revealed that only minor changes in the sequences were appearing. The virus did not seem to be mutating substantially — an indication that the disease would be easier to test for, treat and vaccinate against.
For Dr. Manning, the exercise was proof that even a small research outpost in the developing world could successfully detect new or unexpected pathogens and glean important information about them. As such, her lab and others like it could serve as an early-warning system for the next potential pandemic.
Watching for novel pathogens in Southeast Asia has recently become an important part of the global effort to understand the pandemic. In late January, a group of researchers, most at the Pasteur Institute in Cambodia, announced that it had used metagenomic sequencing to discover a coronavirus closely related to the one that causes Covid-19 in a bat captured in Cambodia in 2010.
“This is what we were looking for, and we found it,” Dr. Veasna Duong, the leader of the study, told Nature in November. “It was exciting and surprising at the same time.”
That finding has drawn attention from researchers who want to better understand how and when viruses cross between species.
Dr. Duong is looking in particular at places where people come near fruit bats. “This kind of exposure might allow the virus to mutate, which might cause a pandemic,” he told the BBC last month.