Cross-sectional serological study of canine Leishmania infection in Fortaleza, Ceará state, Brazil.

Visceral leishmaniasis (VL) is one of the most important reemerging parasitic disease in the world. The domestic dog is the main reservoir in urban environments. The aim of this work was to extend the knowledge on canine Leishmania infection in the city of Fortaleza in northeastern Brazil, identifying the risk factors inherent in dog susceptibility to the infection. Two populations were analyzed, domestic dogs from clinics and the Veterinary Hospital Unit of Ceará State University and stray dogs captured by the Center for Zoonosis Control in Fortaleza. Blood samples were collected and centrifuged and the sera were stored at -20 degrees C. ELISA, with soluble crude Leishmania chagasi antigens (LTCC - WDCM731) was used for diagnosis. A total of 1,381 samples were tested, 750 from domestic and 631 from stray dogs. The seroprevalence of canine VL was 21.4% (135/631) in stray dogs and 26.2% (197/750) in domestic dogs. The seroprevalence of Leishmania infection in the six administrative regions of the city (Secretarias Executivas Regionais, or SER) among stray dogs was highest in SER V, representing 31.4% of the cases, with large dogs more infected (27.7%). Among domestic dogs Leishmania infection was most prevalent in SER V (38.5%) and VI (37.6%). The dogs' age (1-6 years), large size, environment with dense vegetation and presence of clinical signs compatible with Leishmania infection were associated with the illness in domestic dogs. The frequency of the infection varied seasonally. The seroprevalence was greatest in July and December. These results confirm Fortaleza is an endemic area for canine VL and suggest some variables associated with increasing infection risk in dog populations.

The susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis.

Over the last few years, several cases of feline leishmaniasis (FL) with cutaneous and visceral forms have been reported around the world. Nonetheless, the real susceptibility of cats to infection with Leishmania spp. and the outcome of leishmaniasis in these animals are poorly understood. Experimental studies on feline models will contribute to the knowledge of natural FL. Thus, in order to determine the susceptibility of domestic cats (Felis catus) to experimental infection with Leishmania braziliensis, 13 stray cats were infected with 10(7) promastigotes by the intradermal route in the ear and nose simultaneously and followed up for 72 weeks. Soon after infection, the earliest indication of a lesion was a papule on the ear at 2 weeks post-infection (w.p.i.). The emergence of satellite papules around the primary lesion was observed about 4 w.p.i. Two weeks later these papules coalesced and formed a huge and irregular nodule. Thereafter, there was lesion dissemination to the external and marginal surface of the ipsilateral ear, and later to the contralateral ear. At 10 w.p.i., some nodules became ulcerated. Nose lesions presented a similar evolution. At both sites, the largest lesion sizes occurred at 10 w.p.i. and started to decrease 15 days later. Ear and nose nodules healed at 32 and 40 w.p.i., respectively. Specific L. braziliensis IgG antibody titers (optical density> or = 0.01 as positive result) were detected as early as 2 w.p.i. (0.09 +/- 0.02) in only three animals (23%), and all cats had positive titers at 20 w.p.i. (0.34 +/- 0.06). Only three animals (38%) continued to show positive serology at 72 w.p.i. (0.08 +/- 0.02). Up to that time, none of the cats had lesion recurrence. In a feline model of cutaneous leishmaniasis, it seems that there is no correlation between active lesions and positive serology. The implications of these data are discussed.