Common reservoirs for Penicillium marneffei infection in humans and rodents, China

Abstract

Human penicilliosis marneffei is an emerging infectious disease caused by the fungus Penicillium marneffei. High prevalence of infection among bamboo rats of the genera Rhizomys and Cannomys suggest that these rodents are a key facet of the P. marneffei life cycle. We trapped bamboo rats during June 2004-July 2005 across Guangxi Province, China, and demonstrated 100% prevalence of infection. Multilocus genotypes show that P. marneffei isolates from humans are similar to those infecting rats and are in some cases identical. Comparison of our dataset with genotypes recovered from sites across Southeast Asia shows that the overriding component of genetic structure in P. marneffei is spatial, with humans containing a greater diversity of genotypes than rodents. Humans and bamboo rats are sampling an as-yet undiscovered common reservoir of infection, or bamboo rats are a vector for human infections by acting as amplifiers of infectious dispersal stages.

Figure 1

Spatial distribution of sampling sites for Penicillium marneffei, Guangxi Province, People’s Republic of China. 1, Bose; 2, Hechi; 3, Nanning; 4, Liuzhou; 5, Guigang; 6, Guiling; 7, Luchan; 8, Hezhou; Black signifies origin of human-associated isolates, and red signifies origin of bamboo rat–associated isolates; both types were found in some sites.

Figure 2

Neighbor-joining tree of the relationship between multilocus microsatellite type genotypes of human and bamboo rat associated Penicillium marneffei isolates, Guangxi Province, People’s Republic of China. Identical genotypes shared between humans and rats are in boldface. Scale bar indicates nucleotide substitutions per site.