Epidemiology of rabies: characterization of vírus isolated from domestic and wild animals of the semiarid region of Patos, Northeastern Brazil
In the semiarid of the State of Paraíba there are few reports of rabies occurrence, and it is said that caprines, ovines and asinines are resistant to rabies and the use of vaccines in these species is uncommon. This work aimed to study the situation of rabies in the semiarid of Patos-PB, establishing the diagnosis in domestic and wild animals. For the study, 12 foxes (Dusicyon vetulus) were captured alive; 192 insectivorous bats (Molossus molossus), captured at the "Centro de Saúde e Tecnologia Rural-CSTR", of the "Universidade Federal de Campina Grande-UFCG", Patos-PB; and 8 bats (M. molossus) sent by residents of the city of Patos. Captured foxes were submitted to blood collection and then sacrificed using ketamine and T-61. Other 287 foxes and 8 raccoons (Procyon cancrivorus) road-kills collected from the roads serving the Patos municipality were examined. Other 74 samples from different domestic animals sent by the Pathology section of the Veterinary Hospital of the CSTR-UFCG were also included. The wild animals, once shipped to the Virology Laboratory of the CSTR-UFCG, were necropsied and brain fragments were submitted to the fluorescent antibody test (FAT) and mouse inoculation test (MIT) for rabies diagnosis. Among the 581 materials, 50 (8.60%) were positive by FAT, and 47 (8.09%), confirmed by MIT. Concerned to animal species, 19/41 bovines; 12/299 foxes; 1/5 ovines; and 2/6 canines were positive for both FAT and MIT. Caprine, equine and bat samples presented discrepant results between the FAT and MIT, from 2/6 to 1/6; 3/11 to 2/11; 9/200 to 8/200, respectively. All the isolates were sent to the Rabies Laboratory of the "Departamento de Medicina Veterinária Preventiva e Saúde Animal", "Faculdade de Medicina Veterinária e Zootecnia", "Universidade de São Paulo-FMVZ-USP", for extraction of nucleic materials, to perform the antigenic and genetic typing. Antigenic and genetic typing based on M1 gene was conducted at the Canadian Food and Inspection Agency, Fallowfield, Otawa, Canada, sponsored by the IICA ? Inter-American Institutes for Cooperation on Agriculture. The genetic characterization of the N gene and the phylogenetic analyses were made at the National Institute of Infectious Diseases, Toyama, Tokyo, by the researchers of the College of Bioresources Sciences, Nihon University, Kanagawa, Japan. The biologic behavior of the isolates was studied in mice through intracerebral inoculation by registering the incubation and the clinical periods at its first passage. The biologic behavior of a fox isolate was assessed in caprines and ovines, by experimental inoculation through intramuscular route. The same isolate was used for the challenge of asinines and equines that had been vaccinated with a commercially available inactivated virus vaccine. The vaccinated animals showed measurable levels of neutralizing antirabies antibodies and the results of challenge indicated the efficacy of this vaccine against the fox isolate. According to the results of antigenic and genetic typing, it can be concluded that in the region, the epidemiology of rabies is complex, revealing the existence of virus variants maintained in populations of domestic dogs, foxes and hematophagous and insectivorous bats.
Advisor:Fumio Honma Ito; Raul José da Silva Girio; José Antonio Jerez; Samir Issa Samara; Silvio Arruda Vasconcellos; Fumio Honma Ito
School:Universidade de São Paulo
Source Type:Master's Thesis
Keywords: animal rabies
Date of Publication:06/29/2004