UC Davis: melioidosis antibodies persist for years after infection, complicating tests as bacterium spreads in the U.S.

Researchers from the UC Davis School of Medicine and Mahidol University in Thailand have published a study in The Lancet Microbe on how antibodies change over time after melioidosis infection, according to a release on newswise.com. newswise.comnewswise.comnewswise.comOpen source ↗ The work looks at how blood tests for this disease should be read in diagnosis and surveillance.

Melioidosis is caused by the soil-dwelling bacterium Burkholderia pseudomallei, found in tropical and subtropical soil and surface water. It is treated with antibiotics, and its fatality rate is 10% to 50%. People and animals can be infected through contact with contaminated soil, dust or water. Symptoms include fever, stomach pain and seizures, and the disease can resemble pneumonia, tuberculosis or cancer, which is why it is sometimes called "the great mimicker".

Antibody persistence in the Thai cohort

The researchers followed people in Thailand after confirmed melioidosis infections to measure how long antibodies against the bacterium remain detectable. They examined antibody responses to two promising diagnostic targets. Antibody levels can persist for years after infection, so a positive result may reflect past infection rather than recent disease.

According to Kristen Aiemjoy, assistant professor at the UC Davis Department of Public Health Sciences and co-senior author, antibody tests may be especially useful where the disease is rare or newly emerging, since few people have been previously exposed. newswise.comnewswise.comnewswise.comOpen source ↗ Where the disease has circulated for decades, earlier infections make results harder to interpret.

Range of the bacterium

Melioidosis is endemic in northern Australia and Southeast Asia, particularly northeast Thailand. Recent evidence suggests that its range is expanding. In 2022, researchers from the Centers for Disease Control and Prevention linked multiple human infections to soil and water in Mississippi, in a paper published in the New England Journal of Medicine. That finding provided some of the strongest evidence that the bacterium has become established in the continental United States. Reports of the disease are also increasing in South Asia and Africa.

Scientists have warned that climate change could enlarge the areas where the bacterium can survive. Aiemjoy noted that once the organism is established in soil and water, it can persist and replicate for long periods, creating an ongoing risk of exposure. The study is published in The Lancet Microbe, article 101450.