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Histoplasmosis outbreak among Dominican Republic tunnel workers exposed to bat guano

February 05 2018

Between July and September 2015, an outbreak of severe unexplained fevers affected almost every member of a work crew in the Dominican Republic (DR). Of 35 workers in the team, all healthy adult males, 25 were hospitalized and a further 3 died.

Initially leptospirosis was suspected, but patients did not respond to antibiotics. Subsequently, a pathologist found yeast cells while examining a BAL sample microscopically. As outbreaks of histoplasmosis had never been reported previously in the DR, local physicians were unfamiliar with diagnostic techniques and management, so they enlisted the help of the DR Ministry of Public Health and the CDC Mycotic Diseases Branch. Antibody testing on serum and antigen testing (immunoassay) on urine/serum revealed the presence of Histoplasma capsulatum.

Interviews with the patients revealed that the crew had been removing bat guano from access tunnels for several weeks without adequate respiratory protection – workers were provided with loose-fitting paper masks that were not fit for this purpose, and were so uncomfortable that many workers chose not to wear them. Histoplasma is known to form pockets (or ‘hotspots’) within the environment, which release large numbers of spores when disturbed, so shovelling large volumes of bat guano in a poorly-ventilated space was a particularly high-risk activity.

Several lessons can be learned from this outbreak. Firstly, greater awareness of this disease among clinicians should help to expedite diagnosis and treatment in future cases. Secondly, inexpensive point-of-care diagnostics such as lateral flow assays would be invaluable in cases like this where local resources are limited. More generally, it also gives a stark warning to employers about the importance of providing appropriate protective equipment to workers handling biohazardous materials.

Read the full paper: Armstrong et al (2017) Outbreak of Severe Histoplasmosis Among Tunnel Workers—Dominican Republic, 2015. Clin Infect Dis.