Angiostrongylus vasorum: interação parasito, hospedeiros e ambiente

Abstract

Angiostrongylus vasorum, parasite of the cardiorespiratory system in dogs, has heteroxenic biological cycle in which the intermediate hosts are terrestrial and aquatic molluscs. Generally, canids are infected by eating the intermediate hosts or paratenic hosts containing infective larvae (L3). This work brings together four experiments were divided into chapters. In Chapter 1 we evaluated the survival of L1 in the environment using 207 samples of 50 g of stool pool of dogs infected with A. vasorum on waterproof cellophane paper type in places under incidence of sunlight in shady locations, in the refrigerator (4 ° C) and freezer (-20 ° C). We conclude that the L1 A. vasorum support for a longer period of time at lower temperatures (4 ° C) with respect to room temperature (25 ° C) and the direct sunlight on the stool stimulates the migration of the larvae and increases mortality of the same . In Chapter 2 we study the susceptibility, growth, oviposition and larval development in 282 P. canaliculata infected with 500 first stage larvae (L1) of A. vasorum. The larval recovery ranged from 38.2% to 65.9%. L1 were found until 19 dpi, larvae of the second stage (L2) of 11 to 25 dpi and third stage larvae (L3 ) from 19 dpi. The infected snails had higher number of eggs per clutch. However, the rate of onset and the size of the shell were lower in the infected group compared to the control group. This is the first report of experimental infection of P. canaliculata by A. vasorum, confirming its specificity in relation to the intermediate host and indicating the importance of epidemiological surveys targeted to the parasite and this mollusk. In chapter 3 we evaluated the susceptibility and the feasibility of Gallus gallus domesticus as paratenic host of A. vasorum, 17 chickens from Cobb were randomly divided into two groups. The animals in group A were inoculated with L3 of A. vasorum, and group B ate snails infected with L3 of A. vasorum. At thirty days post-infection the chickens were sacrificed and the muscles and organs were placed in a pepsin-HCl solution (1% HCl (37%), 1% pepsin) for 3 hours in an oven at 40 ° C for L3 recover. In group A, 1,863 L3 were recovered by chicken. In group B, 2585 L3 were recovered. A dog that ingested organs and tissues of a group of chicken eliminated the larvae of A. vasorum in their feces 51 days after infection. After 107 days began the treatment with fenbendazole daily doses of 25 mg / kg for 21 days. The L3 to remain viable for 30 days and the infection dog indicate that Gallus gallus is a paratenic potential host for this parasite. In Chapter 4 was analyzed parasitological aspects of the infection in pregnant bitch, we evaluated the existence of anti-A.vasorum antibodies in 15 the breast milk of infected dogs and the kinetics of anti-A. vasorum antibodies in the serum of their pups. In addition, we evaluated the elimination kinetics of first stage larvae (L1) of A. vasorum in the feces of dogs in the estrus phase, pregnancy and lactation. There was transfer of anti- A. vasorum for puppies and these decrease over time in relation to the values found in mothers'. By 45 days after birth of puppies (ABP) antibodies were detected in the serum of all pups at day 90 and only 1 chick presented ABP response to the antigen. After 105 days there was no reaction to the antigen in the sera of pups. No larval form was detected in milk samples. The whey showed antibodies at 15 days ABP and at 30 days was not detected antigen-antibody reaction. There was elimination of L1 A. vasorum in bitch feces in all reproductive phases. Since the second half of pregnancy was an increase in the number of larvae in the feces. This increase coincided with the increase in prolactin levels in pregnant bitches.