Detection of Toxoplasma gondii (T. gondii) DNA in blood can help to diagnose the disease in its acute phase; however, it must be considered that hemoglobin, present in blood, can inhibit polymerase activity, making impracticable the detection of DNA in samples. Mice were experimentally infected via oral route with ME49 and BTU2 strains cysts and RH strain tachyzoites; polymerase chain reaction was used to detect T. gondii DNA in mice sera 18, 24, 48, 96, and 192 hours post infection (PI). Toxoplama gondii DNA was detected in only one animal infected with BTU2 strain, genotype III (isolated from a dog with neurological signs) 18 hours PI. The agent's DNA was not detected in any sample of the other experimental groups. New studies must be carried out to verify the technique sensitivity in researches on this agent's genetic material using sera samples of acute-phase toxoplasmosis patients, especially in cases of immunosuppression.

Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, a coccidian protozoan of worldwide distribution. The seroprevalence in canine population can be an alternative for measuring T. gondii urban spreading. A total of 780 blood samples from dogs were collected, during the yearly anti-rabies campaign, carried out by the Department of Veterinary Hygiene and Public Health, School of Veterinary Medicine and Animal Husbandry (FMVZ), São Paulo State University, UNESP, together with the county health authorities, in August 1999. Using Indirect Fluorescent Antibody Test (IFAT) for detecting antibodies anti-T. gondii in the sera samples, we observed that 258 dogs (33.1%) were positive. The associations between the serological results and the epidemiological variables were studied. Statistically significant differences were not found regarding sex (32.2% male and 34.3% female reactors). Dogs without a defined breed showed seropositivity statistically higher than the pedigreed group. The occurrence of infection was considered higher with age.

Visceral leishmaniasis is a zoonotic disease caused by parasites of the Leishmania genus. Dog is the major source of infection to man, especially in urban areas. The authors report a case of visceral leishmaniasis in a pit bull female dog from Bocaina, São Paulo, Brazil. The animal presented clinical signs compatible with leishmaniasis, including skin lesions in the body and partial damage of the external ears. The indirect fluorescent antibody test (IFAT) demonstrated a titer of 1280, and promastigote forms of Leishmania sp were isolated by the culture of bone marrow puncture. Cytological analysis of the lymph node and smear of the bone marrow puncture revealed macrophages containing amastigote forms of Leishmania sp in their inner region. The test of Polymerase Chain Reaction (PCR) utilized the primers LINR4 and LIN19, which amplify 720 base pairs, specific for Leishmania sp. The authors discuss the importance of techniques for a quick and precise diagnosis to this serious zoonosis with great impact in animal and public health.