TEMPO.CO, Jakarta - Indonesia experienced plague outbreaks in the early 20th century, particularly in Java. The disease, caused by the bacterium Yersinia pestis, is one of the deadliest known infections and is transmitted through fleas living on rats.
Although no human cases have been recorded in recent years, researchers warn this does not mean Indonesia is completely free from the disease.
BRIN researcher Ristiyanto said the plague may be in a “silent period.”
“There is a term called the silent period, which is a period when a disease is not detected for a long time, but actually still has the potential to reappear,” he said in a written statement on Monday (March 13, 2026).
He added that the bacterium, along with its vectors and reservoirs such as fleas and rats, is still found in several enzootic areas in Indonesia.
Environmental changes, he noted, play a key role in increasing the risk of re-emergence. Deforestation, land-use change, and population growth have disrupted ecosystems and pushed rodent habitats closer to human settlements.
“This condition increases the chances of disease transmission through the bite of fleas carrying the bacteria,” he said.
Another BRIN researcher, Muhammad Choirul Hidajat, also pointed to climate change as a factor contributing to rising flea populations. “The combination of environmental changes, the presence of vectors and reservoirs, and increasing interaction with humans are the main risk factors that need to be anticipated,” he said.
He added that rats, the main reservoir of Yersinia pestis, remain widely found across Indonesia, and transmission to humans can occur through infected fleas.
Although no human cases have been reported for more than a decade, several areas in Java, including Pasuruan, Boyolali, Sleman, and Bandung, are still classified as plague focus areas. Choirul stressed this should not be taken lightly, noting that the absence of cases does not mean the disease has disappeared.
As a preventive measure, he called for stronger integrated surveillance covering humans, animals, and disease vectors, alongside improved sanitation and monitoring of former endemic zones.
“The plague in Indonesia may currently be ‘asleep’. However, without vigilance and good environmental management, this disease has the potential to reappear,” he said.
The study, titled Environmental Changes and Risk of Plague Epidemics in Indonesia, was conducted through collaboration between BRIN, the Ministry of Health, and international partners from China and France.
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