Feral pigs as hosts for Amblyomma sculptum (Acari: Ixodidae) populations in the Pantanal, Mato Grosso do Sul, Brazil.

The Pantanal in Brazil is the largest floodplain of the world. This ecosystem, rich in wildlife, has a large feral pig population. Such a large host biomass must have a strong influence on the parasite fauna. In this work, we evaluated the role of feral pigs in the maintenance of Amblyomma sculptum (formerly Amblyomma cajennense), the most prevalent tick species in the Pantanal. Tick infestations were evaluated on 243 feral pigs and their environment. The suitability of domestic pigs, representing their feral relatives, to A. sculptum adults and nymphs was assessed experimentally. Tick infestation of feral pigs was strongly associated with that of the environment: 96 and 97 % of the ticks, respectively, were A. sculptum. The infestation prevalence on this host species was close to 90 % in the dry season and 100 % in the wet season and mean infestation intensity was above 30 ticks in both seasons. Suitability of pigs as hosts for A. sculptum was shown by the high proportion of nymphs and female ticks found engorging on captured feral pigs and adequate biological parameters displayed by ticks from experimental infestations of domestic pigs. Other tick species on feral pigs, albeit in much lower numbers, were Amblyomma parvum and Ornithodorus rostratus. Results show that feral pigs feed a high proportion of the A. sculptum adults and nymphs in their territories and should be a target for tick-borne diseases studies. This is particularly relevant to public health because all the main tick species found on feral pigs are aggressive to humans as well.

Pathogenesis of Trypanosoma evansi infection in dogs and horses: hematological and clinical aspects / Patogênese da infecção pelo Trypanosoma evansi em cães e cavalos: aspectos hematológicos e clínicos

Trypanosoma evansi caused severe anemia in horses and pronounced leukopenia in dogs, both naturally infected. The horses presented microcytic normochromic anemia and the dogs showed microcytic hypochromic anemia. The clinical signs observed were fever, anemia, edema of the legs and lower parts, weakness and inappetence. Light microscopic studies demonstrated that Trypanosoma evansi produced several alterations in erythrocytes of dogs and horses. These pathologic changes included vacuolation, acanthocytes, dacrocytes, codocytes, microspherocytes and bizarre shapes. Mature erythrocyte were observed adhered to trypanosomes. Erythrophagocytosis was also demonstred.

Trypanosoma evansi produziu severa anemia em cavalos e pronunciada leucopenia em cães, ambos naturalmente infectados. Os cavalos apresentaram anemia microcítica normocrômica e os cães desenvolveram uma anemia microcítica hipocrômica. Os sinais clínicos foram febre, anemia, edema das pernas e porções inferiores, fraqueza e inapetência. Estudos com microscopia ótica demonstraram que o Trypanosoma evansi produziu várias alterações nos eritrócitos dos cães e cavalos. Estas alterações patológicas incluíram vacuolação, acantócitos, dacrócitos, codócitos, microesferócitos e formas bizarras. Eritrócitos maduros foram observados aderidos a tripanosomas. Eritrofagocitose foi também observada.