On a break from dancing to songs covered by a Cambodian pop star in Phnom Penh, members of two families clad in blue jumpsuits who appeared by their beds told the story of a child they were forced to watch being led out of the hospital earlier this month. It was the hospital’s only case of the deadly virus — a response as laudable as it was shocking, considering that the child came from a rural village that, in what the two Cambodian men told The Nation of Singapore, is filled with chicken sellers who never wash their hands and who mistake fevers as intestinal problems.

The disturbing news came as Donald Trump signaled for the first time that the United States would need to build another large military base in Asia, upping the possibility of what the Cambodia story demonstrates are the dangers of contagion: the multiple airports and densely packed cities of Asia — particularly rural Cambodia and Vietnam, a U.S. ally — make it an easy place for the virus to spread and kill.

When a girl is infected with the virus, she also infects not only other children, she infects the uncle who fed her the meat that made her sick. So even though the United States helped Cambodia investigate and determine how this sickness was happening, Cambodian officials told the two men not to reveal the details of the epidemic. “It would have led to more people being infected,” said Tine Lareth, an assistant professor of epidemiology at the University of Miami’s School of Public Health.

With U.S. President Donald Trump backing the prime minister of the Philippines in his campaign to crackdown on alleged drug lords on his home island, Duterte has become a geopolitical proxy in the south-east Asian region. China, which has bases in Cambodia, and Vietnam, which has U.S. forces stationed in its port city of Cam Ranh Bay in Vietnam, will have an incentive to make sure that Mr. Trump doesn’t follow through on his campaign promises. So will South Korean Prime Minister Hwang Kyo-ahn. As the Center for Strategic and International Studies’ Asia director, the former foreign minister said this week that the virus represents a problem not just for Cambodia, but for its neighbors. “The latest outbreak of Nipah virus has piqued the concern of friends and partners in the region,” said Mr. Hwang, who made his remarks in Tokyo. “Their primary concern is that Nipah is possibly the result of a failed containment effort that could have an adverse effect on social, economic and political stability in Cambodia and the region.”