Sarcocystis spp. in sheep and goats: frequency of infection and species identification by morphological, ultrastructural, and molecular tests in Bahia, Brazil.

Sarcocystis spp. are cyst-forming coccidia that infect numerous animals species, including several livestock species. Despite the importance of sheep and goat production in Brazil, little it is known about the Sarcocystis species that infect small ruminants in the country and their potential impact on meat condemnation due to the presence of macroscopic cysts of the parasite. The aims of the present study were to determine the frequency of infection by Sarcocystis spp. in goats and sheep intended for human consumption in Bahia State, Brazil, as well as to identify the parasite species in selected samples. The entire tongue, esophagus, and heart were collected from 120 goats and 120 sheep. Tissues were examined for Sarcocystis spp. by macroscopic evaluation, light microscopy, electron microscopy, and molecular tests. Microscopic cysts of Sarcocystis spp. were detected in 95.8 % of sheep and 91.6 % of goats. Using either transmission electron microscopy or partial sequencing of the 18S region of the ribosomal DNA (rDNA) for species identification, Sarcocystis tenella and Sarcocystis arieticanis were observed in sheep and Sarcocystis capracanis in goats. Macroscopic cysts were not detected in the analyzed samples. We concluded that goats and sheep destined for human consumption in Bahia possess high frequencies of Sarcocystis infection. Carcass condemnation due to Sarcocystis macrocysts seems to be rare in the studied region. S. arieticanis and S. capracanis were confirmed for the first time by electron microscopy or by molecular tests in small ruminants from Brazil.

Quantification of Leishmania infantum DNA in the bone marrow, lymph node and spleen of dogs.

The aim of the present study was to quantify the parasite load of Leishmania infantum in dogs using real-time PCR (qPCR). Bone marrow, lymph node and spleen samples were taken from 24 dogs serologically positive for L. infantum that had been put down by the official epidemiological surveillance service. According to the clinical signs the dogs were classified as asymptomatic or symptomatic. After DNA extraction, the samples were subjected to qPCR to detect and quantify L. infantum DNA. Out of the 24 dogs, 12.5% (3/24) were classified as asymptomatic and 87.5% (21/24) as symptomatic. Real-time PCR detected L. infantum DNA in all the animals, in at least one biological sample. In particular, 100% of bone marrow and lymph node scored positive, whereas in spleen, the presence of DNA was detected in 95.9% (23/24). In addition, out of 24 animals, 15 were microscopically positive to amastigote forms of L. infantum in bone marrow. No statistical significant difference was found in the overall mean quantity of DNA among the different biological samples (P = 0.518). Considering each organ separately, there was 100% positivity in bone marrow and lymph nodes, while among the spleen samples, 95.9% (23/24) were positive. Regarding the different clinical groups, the overall mean parasite load varied significantly (P = 0.022). According to the results obtained, it was not possible determine which biological sample was most suitable tissue for the diagnosis, based only on the parasite load. Therefore, other characteristics such as convenience and easily of obtaining samples should be taken into consideration.