Differentiating New from Newly Detected: Melioidosis in Yap, Federated States of Micronesia

Melioidosis is a bacterial infection caused by exposure to water or soil that contains Burkholderia pseudomallei (Bp). Burkholderia pseudomallei is endemic to many tropical and subtropical areas of the world. In 2013, the first case of melioidosis was recognized in Yap, the Federated States of Micronesia. Six additional cases were identified in the subsequent 3 years. An investigation was initiated to understand the epidemiology of melioidosis in Yap. Serum from family and community members of the identified cases were tested for antibodies to Bp. Archived serum from a 2007 Zika serosurvey were also tested for antibodies to Bp. Sequencing of bacterial isolates was performed to understand bacterial phylogeny. Soil and water were tested for the presence of Bp in the environment by culture and PCR. None of the affected patients had a history of travel to melioidosis-endemic countries. Two of the 34 (5.8%) samples from the field investigation and 67 (11.7%) of the historical samples demonstrated serologic evidence of prior Bp exposure. No Bp were detected from 30 soil or water samples. Genotype analysis showed highly related Bp isolates that were unique to Yap. Melioidosis is likely to be endemic to Yap; however, it has only recently been recognized by the clinical community in country. Further investigation is needed to understand the local sites that harbor Bp and represent the highest risk to the community.