Is Microspiridial Infection in Animals a Potential Source for Human Microsporidiosis?

Microsporidiosis is an emerging infectious disease among a rapidly-broadening clinical spectrum of diseases that can cause significant morbidity in immunocompromized and immunocompetent patients, especially in patients with acquired immunodeficiency syndrome (AIDS). Acquired infection seems to occur from personto-person transmission or from other sources (eg water, food, and animals). Several microsporidia species that are pathogenic for humans have been identified in domestic and wild animals. The aims of this study were to determine the presence of microsporidian spores in stool samples from animals and to identify the species implicated in infection, in Portugal. A total of 352 stool samples from animals (117 pets, 99 animals from the Zoo, 51 bovines, and 85 sylvatic animals) were studied. Modified trichrome stain, IFA with MAb 3B6 and PCR with species-specific primers for Enterocytozoon bieneusi, Encephalitozoon intestinalis, E. cuniculi, and E. hellem SSU-rRNA gene followed by nucleotide sequencing were the methods used. Microsporidian spores were identified in stools from 32 (27%) pets and 15 (15%) animals from the Zoo, presenting 38 (81%) of these animals with low to moderate parasite loads. All stool samples from small rodents were negative for microsporidia by MT and IFA. By PCR, 13 isolates (4 from cats, 3 from dogs, 1 from a white-fronted marmoset, and 5 from bovines) were identified as being E. bieneusi-positive and confirmed by sequencing. In conclusion, animals in close contact with humans harbor microsporidia species also identified in humans, releasing spores into the environment with feces that can be a source of human infection. This study sets the framework for further studies on the epidemiology of microsporidia infection in Portugal. animals (Wright and Craighead, 1922; Levaditi et al, 1923; Didier et al, 1995; Deplazes et al, 1996a,b; Mathis et al, 1996, 1999; Black et al, 1997; Mansfield et al, 1997; Bornay-Llinares et al, 1998; Pulparampil et al, 1998; Breitenmoser et al, 1999; Del Aguila et al, 1999; Rinder et al, 2000; Snowden et al, 2000; Dengjel et al, 2001; Buckholt et al, 2002; Graczyk et al, 2002; Lores et al, 2002; MullerDoblies et al, 2002; Fayer et al, 2003; Lobo et al, 2003; Sulaiman et al, 2003). Although this fact supports the hypothesis that human infections may be a zoonosis, direct evidence of transmission from animals to humans is still lacking. Persons or animals infected with these parasites release spores into the environment through feces, urine or respiratory secretions that may be potential sources of infection. In Portugal, 51, 18 and 7% of microsporidian spores were detected, respectively, in feces, pulmonary specimens, and urine of AIDS patients (Matos et al, 2001, 2002), and 46% in feces from immunocompetent individuals (Lobo et al, 2002). The great majority of the intestinal infections were symptomatic, ranging from gastrointestinal complaints without diarrhea, transient diarrhea (in immunocompetent patients) to chronic diarrhea (in immunocompromized patients). This study aimed to identify potential animal sources (domestic and sylvatic animals) of human Correspondence: Olga Matos, Unidade de Protozoários Oportunistas/VIH e outras Protozooses, Instituto de Higiene e Medicina Tropical, Rua da Junqueira 96, 1349-008 Lisboa, Portugal. Tel: 3512-1363-2600; Fax: 3512-1363-2105; E-mail: [email protected] INTRODUCTION Microsporidia are obligate intracellular protozoan parasites infecting a broad range of vertebrates and invertebrates. During the past decade, several genera of microsporidia have been identified in immunocompromized patients, especially those with acquired immunodeficiency syndrome (AIDS) (Weiss, 2001), and more recently in immunocompetent persons (Weiss, 2001; Matos et al, 2001, 2002; Lobo et al, 2002). Microsporidia can cause a wide spectrum of intestinal or disseminated pathologies depending on the infectious species involved and also on the immune status of the host. Routes of transmission and sources of human microsporidial infections have been difficult to ascertain. Acquired infection seems to occur from person-to-person transmission or from other sources (eg water, food, and animals). Several microsporidia species pathogenic to humans have been identified in domestic and wild