Wild animals, just as other living beings, are subject to changes in their natural environment determined by evolution processes and by alteration or damages to their natural ecosystems by anthropogenic actions¹. In particular, cavern-like environments are used by middle-sized (carnivorous, edentates and marsupials) and small-sized (bats and mice) animals as shelters or in search for food. Frequently, these environments are part of their activity area including their territory and, in some cases, these can be modified by human activities. These environments, as well as other sites where microclimatic conditions favorable for the development of the H. capsulatum pathogen are established, represent an infection risk for mammals in general, including the human being¹. Emmons², in 1958, evidenced for the first time the relationship between bats' habitat and the presence of the pathogen. In Mexico, Aguirre-Pequeño³, in 1959, and Gonzalez-Ochoa⁴, in 1963, corroborated this relationship.

ISOLATES, INFECTION, AND DISEASE REGISTERS

Although there are reports on the isolation of the fungus from bird droppings, the disease itself or natural infection in these animals has not been described in the corresponding literature. In India, Chandel and Kher⁵, described an unusual case of histoplasmosis in camels (Camelus dromedarius). Table 1 depicts the disease registers reported for wild-terrestrial mammals made by different authors and classified according to Wilson and Reeder⁶. The subclinical infection in wild mammals has been detected in a captive population ⁷, by using a skin test with the fungal histoplasmin antigen in order to determine past or present infection, finding a global response of positive intradermoreaction of 44.79%, distributed among: primates -. Cebidae Fam., 15.15% and Callitricidae Fam. 6.25%; carnivorous -. Procyonidae Fam., 86.49% and Felidae Fam.,50%, demonstrating with this study that there is a high rate of infection caused by the fungus in captive animals⁷. Recently, at the Africam Safari, located in the state of Puebla, MX, Arely et al. described the natural infection by H. capsulatum in a mara or Patagonian hare (Dolichotis patagonum). In Guadalajara, Jalisco, MX, Espinosa et al. referred infection in a captive leopard.

Figure 1. Night pollination of cacti by bats

Kunz⁸, in 1988, compiled data on bats natural infection published around the world, where the fungus has been isolated. Studies performed by Fernandez-Andreu⁹ and by Taylor et al.^10-11 include new isolates that represent first records for the American continent and Mexico. During the last 10 years a large number of H. capsulatum isolates have been obtained from infected bats in Mexico.

Figure 2. Infraworld and fertilizing god in "Zapotec" culture, Oaxaca, MX

The relevance of natural infection with the fungus in bats is a very interesting issue, considering different aspects such as environmental education of the population poorly informed on the real value of bats as ecosystem moderators (Figure 1), as active participants of biodiversity processes, as hosts to the fungus, besides other interesting aspects, including archaeological ones (Figure 2). Vincent et al.¹², in 1986, through DNA fragments analysis by restriction enzymes (RFLP), determined the genetic polymorphism of two fungal strains isolated from infected animals, an opossum and a cat¹², which they grouped molecularly under class 2, which encompasses almost all the H. capsulatum strains isolated in the USA. This suggests that both humans and wild or domestic animals are exposed to the same type of strains from different infection sources in nature. During the last years, research groups from the Laboratories of Fungi Immunology and Molecular Mycology of the Department of Microbiology and Parasitology of the Medicine School at UNAM, in association with mastozoologists from the Zoology Laboratory of the Iztacala Campus from UNAM have studied and grouped fungal isolates from bats naturally infected and captured in the Mexican territory. This research has allowed to identify a molecular-geographic pattern of the fungus associated both to wild hosts and to humans¹³.

REFERENCES

1. González-Zepeda I, Vargas-Yáñez R, Velasco-Castrejón O, Taylor ML. Histoplasmosis. Rev Fac Med (UNAM) 1998;41:12-15.
   
2. Emmons CW. Association of bats with histoplasmosis. Public Health Rep 1958;73:590-595.
   
3. Aguirre-Pequeño E. Aislamiento de Histoplasma capsulatum del guano de murciélago en cuevas del noreste de Mexico. Gac Med Mex 1959;89:243-257.
   
4. González-Ochoa A. Relaciones entre el hábitat del murciélago y el Histoplasma capsulatum. Rev Inst Salubr Enf Trop (Méx) 1963;23:81-86.
   
5. Chandel BS, Kher HN. Occurrence of histoplasmosis like disease in camel (Camelus dromedarius). Indian Vet J 1994;71:521-523.
   
6. Wilson DE, Reeder DM. Mammals Species of the World. A Taxonomic and Geographic References. 2nd ed. Washington: Smithsonian Institution Press, 1993.
   
7. Costa EO, Diniz LSM, Fava Netto C, Arruda C, Dagli MLZ. Epidemiological study of sporotrichosis and histoplasmosis in a captive Latin American wild mammals, Sao Paulo, Brazil. Mycopathologia 1994;125:19-22.
   
8. Kunz TH. Ecological and Behavioral Methods for the Study of Bats. London: Smithsonian Institution Press, 1988.
   
9. Fernández-Andreu CM. Aislamiento de Histoplasma capsulatum en murciélagos en Cuba. Rev Cubana Med Trop 1988;40:36-43.
   
10. Taylor ML, Toriello C, Pérez-Mejía A, Martínez MA, Reyes Montes MR, Espinosa-Avila L, Chávez-Tapia C. Histoplasmosis in the State of Guerrero, Mexico: A biological approach. Rev Mex Mic 1994;10:49-62.
    
11. Taylor ML, Chávez-Tapia CB, Vargas-Yañez R, Rodríguez-Arellanes G, Peña-Sandoval GR, Toriello C, Reyes-Montes MR. Environmental conditions favoring bat infection with Histoplasma capsulatum in Mexican shelters. Am J Trop Med Hyg 1999;61:914-9.
    
12. Vincent RD, Goewert R, Goldman WE, Kobayashi G, Lambowitz AM, Medoff G. Classification of Histoplasma capsulatum isolates by restriction fragment polymorphims. J Bacteriol 1986;165:813-818.
    
13. Taylor ML, Chávez-Tapia CB, Reyes-Montes MR. Molecular typing of Histoplasma capsulatum isolated from infected bats, captured in Mexico. Fung Genet Biol 2000;30:207-12.