Role of Cannomys badius as a natural animal host of Penicillium marneffei in India

Abstract

Infection by Penicillium marneffei in human immunodeficiency virus-positive patients in India has recently been described; the aim of our study was to survey wild rodents and their associated environment in order to identify the natural populations of this fungus. Surveys recovered P. marneffei from the internal organs of 10 (9.1%) of 110 bamboo rats (Cannomys badius) examined from Manipur state, India, an area endemic for penicilliosis marneffei. Identification of the isolates was based on a detailed study of their morphological characteristics, in vitro conversion to fission yeast form, and exoantigen tests. Multilocus microsatellite typing (MLMT) of the isolates revealed five genotypes. No genotypes were shared between sample sites, and all bamboo rats were infected with a single genotype within sample sites, demonstrating spatial genetic heterogeneity. One MLMT genotype was identical to that seen in a human isolate, suggesting that either coinfection from a common source or host-to-host transmission had occurred. This demonstrates the utility of an MLMT-based approach to elucidating the epidemiology of P. marneffei.

FIG. 1.

Map of Manipur state, showing the locations of the Senapati and Tamenglong districts where bamboo rats were trapped. Bamboo rats were trapped on four separate bamboo plantations within the Tamenglong district.

FIG. 2.

(A) Lactophenol blue mount of 7 days' growth of P. marneffei (isolate VPCI 214) showing characteristic biverticillate and monverticillate penicilli. Magnification, ×425. (B) Lactophenol blue mount of 3 days' growth of P. marneffei isolate (VPCI 214), showing fission yeast form. Magnification, ×425.

FIG. 3.

Neighbor-joining tree showing the relationships between the 10 recovered isolates and the CBS 101038 clinical isolate. Numbers following the districts refer to the bamboo plantations where the bamboo rats were trapped.