Dispersion of Echinococcus granulosus eggs from infected dogs under natural conditions in Patagonia, Argentina.

Cystic echinococcosis caused by Echinococcus granulosus is a major zoonosis of public health significance in the Patagonian region of Argentina. This investigation sought to test the hypothesis that the persistence and dispersion of the parasite eggs can be explained by physical and meteorological parameters along with final host infection and behaviour. This observational study was carried out over a five-year period within an enclosure where two dogs harbouring a worm burden ranging from 100 to 1000 mature adult E. granulosus, as well as two uninfected dogs, had previously been kept for six months. Environmental canine faeces, topsoil, pond water, and sediment samples were examined to control for the presence of eggs and coproantigens of the parasite using microscope-based techniques and copro-ELISA plus copro-Western Blot tests. The parasite eggs were detected up to 41 months later in faeces from infected dogs, soil and sediment, and coproantigen tests remained positive for up to 70 months in faeces. Overall, parasite eggs were found within a maximum distance of 115 m from the contaminated dog faeces deposition site. Our findings indicate that under Patagonian environmental conditions, egg persistence and dispersion seem to be related to the worm burden and habits of the infected dog, to prevailing wind direction and to the existence of low bushes as well as natural bodies of water. The present study is the first to provide direct evidence of interaction between bioclimatic conditions and E. granulosus egg dispersion under Patagonian field conditions.

Evaluation of the presence of Echinococcus granulosus sensu lato in the environment and in hosts in a region endemic for hydatidosis in the province of Chubut (Argentina).

In the province of Chubut (Argentina), hydatidosis is an endemic disease. This province has had a program for control of this disease since 1984. The aim of the present study was to evaluate the presence of Echinococcus granulosus sensu lato in the environment and hosts in a region characterized as endemic and inhabited by indigenous people whose sustenance economy is based on the extensive rearing of sheep. To this end, we carried out an observational, descriptive and transversal study. Sheep sera, water samples, soil samples and canine fecal matter collected from the environment and adult specimens of E. granulosus s.l. were analyzed for strain studies by genotyping. Also there were analyzed serum samples of resident persons to detect E. granulosus antibodies. The frequency of sera positive for hydatidosis was 17.5% in lambs and 28.57% in sheep older than one year of age. The frequency of canine echinococcosis was 25%, and the strain found corresponded to E. granulosus s.l. G1. Samples of canine fecal matter showed presence of taeniid eggs and three of the samples were positive for the coproantigen. The results indicate the circulation of the G1 strain and its presence in the environment under the dry climate conditions of Patagonia. These findings provide useful information for the evaluation of the effectiveness of control actions that may be implemented in a region endemic for hydatidosis.

A descriptive study of the occurrence and significance of lipids in Taenia hydatigena eggs.

The aim of this work was to investigate the lipid content of Taenia hydatigena eggs and to evaluate the role of lipids in the maintenance of embryo viability. The total lipid content of the egg was 4.5% (w/w). Five classes of neutral lipids were identified: esterified cholesterol, free cholesterol, triacylglycerols, diacylglycerols and free fatty acids. Our results suggest that triacylglycerols play a key role in the maintenance of embryo viability. In addition, we found that T. hydatigena eggs remain metabolically active by mobilisation of stored triacylglycerols. This study contributes to the understanding the survival strategies of a member of the Taeniidae family in the environment outside the host.

Comparison of preparation techniques of mixed samples (fungi-helminth eggs) for scanning electron microscopy by critical point drying.

We compared three preparation techniques for critical point drying of fungus Paecilomyces lilacinus (Thom) Samson with Toxocara canis (Werner) Johnston and Taenia hydatigena Linneo eggs by scanning electron microscopy. We evaluated filtration (first), centrifugation (second), and phytoplankton network (third) in critical point drying methods. The first and third methods were advantageous for T. canis eggs because they preserved the quantity and quality of samples to obtain better images definition. The best technique for T. hydatigena eggs was the addition of phytoplankton network in critical point drying which preserved these helminth eggs.

Presence and persistence of intestinal parasites in canine fecal material collected from the environment in the Province of Chubut, Argentine Patagonia.

We investigated the presence of intestinal parasites in canine feces collected from public squares in Comodoro Rivadavia, Chubut, Argentina (45 degrees S, 68 degrees W) and determined the persistence of Echinococcus granulosus eggs in those droppings under natural environmental conditions in that region. In the first experiment, we analyzed 163 fecal samples collected from urban squares during 8 months time and found parasitic elements in 46.6%. The presence of parasites was independent of the condition of the feces (fresh or dried; P>0.05). Parasites potentially pathogenic in man were present, such as Toxocara species (spp.), Taenia spp./Echinococcus spp., Uncinarias spp., and Entamoeba spp. In the second experiment, we analyzed two canine fecal samples contaminated with E. granulosus eggs, deposited for 41 months within the natural environment. These parasitic elements persisted during the entire study as attested by light microscopy and the ELISA coproantigen test. We propose the study of the presence of intestinal parasites in canine feces within the environment as a general strategy for identifying and monitoring areas of risk for canine-related zoonoses since we were able to demonstrate the persistence of E. granulosus eggs in deposited canine feces for over 3 years within the area studied.