Pitiose cutânea em bovinos na região Sul do Rio Grande do Sul / Cutaneous pythiosis in cattle in the Southern region of Rio Grande do Sul, Brazil

Descreve-se a ocorrência de pitiose cutânea em bovinos de corte na região sul do Rio Grande do Sul. Os animais foram introduzidos em área alagada e desenvolveram lesões cutâneas ulcerativas e úmidas, de tamanhos variados, localizadas na região distal dos membros e no chanfro nasal. Histologicamente, as lesões eram caracterizadas por múltiplos granulomas com hifas intralesionais, melhor observadas pela coloração de metenamina nitrato de prata de Gomori, e circundadas por abundante tecido conjuntivo fibroso. O diagnóstico foi realizado com base na epidemiologia, lesões macroscópicas e histológicas e pela reação imuno-histoquímica positiva com anticorpo policlonal anti-Pythium insidiosum. A morbidade foi de 23,8 por cento e os animais adoeceram 15-90 dias após a introdução na área alagada. Em todos os casos as lesões evoluíram para a cura sem tratamento. Sugere-se que a doença possa ser mais frequente em bovinos do que se supõe, principalmente em áreas alagadas da região Sul do Rio Grande do Sul.

An outbreak of cutaneous pythiosis is described in cattle from southern Rio Grande do Sul, Brazil. Cattle were introduced into flooded pastures and developed ulcerative and wet cutaneous lesions on distal limbs and Planum nasale. Histologically, the lesions were characterized by multiple granulomas with intralesional hyphae, better seen in the methenamine silver stain, and surrounded by abundant fibrous tissue. Diagnosis was based on epidemiology, gross and histological lesions, and by positive immuno-histochemical reaction with anti-Pythium insidiosum polyclonal antibody. Morbidity was 23.8 percent and lesions were observed 15-90 days after cattle were introduced in the flooded area. Affected cattle had spontaneous healing without treatment. It is suggested that the disease is more frequent than what was earlier thought, mainly in flooded areas of the Southern region of the Rio Grande do Sul State.

Efecto de la calidad del agua de criaderos de mosquitos (Diptera: Culicidae) sobre la patogenicidad e infectividad de las zoosporas del hongo Leptolegnia chapmanii (Straminipila: Peronosporomycetes)

Effect of water quality in mosquito breeding sites on the pathogenicity and infectivity of zoospores from the fungus Leptolegnia chapmanii (Straminipila: Peronosporomycetes). The fungus Leptolegnia chapmanii is highly pathogenic to mosquito larvae in Argentina. We studied if physical and chemical characteristics of the water from mosquito breeding sites affect pathogenicity, and the infectivity of zoospores of L. chapmanii. Water samples were taken from pools filled by rains, urban ditches with domestic waste water, pools filled by overflow from Río de la Plata, and flower vases from the Cemetery of La Plata city. Sub-samples of water were analyzed for physical and chemical characteristics, while other sub-samples were used for laboratory bioassays. Containers with 150 ml of water samples, 25 Aedes aegypti larvae, and 2.8 x 105 zoospores of L. chapmanii, were incubated under controlled environment, and larval mortality was recorded after 48 h. There were highly significant differences among mortalities in water from cemetery vases (70.2%), rain pools water (99.5%), and pools with water from Rio de la Plata (95%). There were no significant differences among larval mortalities in water from ditches, rain pools and Río de la Plata pools. Leptolegnia chapmanii was successful as a biological control agent in all kinds of tested water qualities, producing high larval mortality. Rev. Biol. Trop. 57 (1-2): 371-380. Epub 2009 June 30.

Leptolegnia chapmanii es un potente patógeno de larvas de mosquitos. El objetivo del trabajo fue determinar si las características físico-químicas del agua de criaderos de culícidos de importancia sanitaria a nivel mundial afectan la patogenicidad e infectividad de las zoosporas de L. chapmanii. Se tomaron muestras de cuatro tipos de agua en Argentina: de lluvia, de zanja, del Río de La Plata, y de floreros del cementerio local. A una parte del agua se le realizaron estudios físicos-químicos, y otra parte fue utilizada en ensayos. Se colocó 150 ml de cada muestra en recipientes plásticos, con 25 larvas sanas de Aedes aegypti y 2.8 x 105 zoosporas de L. chapmanii. Fueron incubadas a 25 ºC y 12-12 (L-O). La mortalidad larval fue registrada a las 48 horas. Se utilizaron tres recipientes y un control por tratamiento, con tres repeticiones realizadas en distintos días. Se observaron diferencias altamente significativas entre la mortalidad larval en aguas de floreros del cementerio (70.2%), aguas de lluvias (99.53%), y del río de La Plata (95%). No hubo diferencias significativas entre la mortalidad larval en agua de zanja, lluvia y río. Leptolegnia chapmanii resultó exitoso en los cuatro tipos de aguas evaluados, produciendo elevados niveles de mortalidad larval.