Detection of Environmental Sources of Histoplasma capsulatum in Chiang Mai, Thailand, by Nested PCR

Abstract

Histoplasmosis is a systemic mycosis caused by inhaling spores of Histoplasma capsulatum, a dimorphic fungus. This fungus grows in soil contaminated with bat and avian excreta. Each year, patients with disseminated histoplasmosis have been diagnosed in Chiang Mai, northern Thailand. No published information is currently available on the environmental sources of this fungus in Chiang Mai or anywhere else in Thailand. The aim of this study was to detect H. capsulatum in soil samples contaminated with bat guano and avian droppings by nested PCR. Two hundred and sixty-five samples were collected from the following three sources: soil contaminated with bat guano, 88 samples; soil contaminated with bird droppings, 86 samples; and soil contaminated with chicken droppings, 91 samples. Genomic DNA was directly extracted from each sample, and H. capsulatum was detected by nested PCR using a primer set specific to a gene encoding 100-kDa-like protein (HcI, HcII and HcIII, HcIV). Histoplasma capsulatum was detected in seven of 88 soil samples contaminated with bat guano, one of 21 soil samples contaminated with pigeon droppings and 10 of 91 soil samples contaminated with chicken droppings. The results indicate the possibility of the association of bat guano and chicken droppings with H. capsulatum in this area of Thailand.

Histoplasmosis Infections Worldwide: Thinking Outside of the Ohio River Valley

“…In Thailand, the AIDS epidemic has been responsible of a dramatic upsurge of disseminated histoplasmosis with more than 1200 cases reported to the Ministry of Public Health from 1984 to 2010 65 . A survey of histoplasmin sensitivity conducted in this country between 1966 and 1968 showed positivity rates of 7–14% in the northern region and 15–36% in the Southeast and Southern regions 43 , overlapping with areas containing Penicillium marneffei as determined by PCR 65 .…”

Effect of Pigeon Keeping on Health and Family Life

“…The infections which have been found to be transmitted from pigeons to humans include campylobacters [33], Chlamydia psittaci, [34,35], Cryptococcus neoformans/Candida albicans [36][37][38][39], Escherichia coli [40,41], Histoplasma capsulatum (from fungus growing on dried feces) [42], Salmonella enterica/S. typhimurium [33,[42][43][44] and viral infections (transmitted by mosquitoes feeding on infected birds) [45,46].…”

“…typhimurium [33,[42][43][44] and viral infections (transmitted by mosquitoes feeding on infected birds) [45,46]. Not only are the pigeon keepers/breeders/ fanciers at risk to develop the above diseases, but also member of their families who reside with them [24] and are exposed to bird droppings or feather dust.…”

Histoplasmosis in Pulmonary Infection Patients from Hospitals in Hanoi, Vietnam

“…The occurrence of histoplasmosis in Asia has been recently reviewed with cases of histoplasmosis from India, Malaysia, Singapore, Indonesia, Thailand, South Vietnam and Japan, but the autochthonous nature of the cases reported has not been established unequivocally [8,12,13]. Recently, H. capsulatum was recovered from environmental sources contaminated with bat guano and chicken droppings in Thailand [14]. In Vietnam, two histoplasmosis cases were reported from Southern Vietnam, however, the endemicity of the disease has not been studied.…”