Toxocariasis, Intestinal Parasitoses and Eosinophilia in Schoolchildren from Argentina.

The purpose was to analyze the relationship between toxocariasis, intestinal parasitosis, eosinophilia, pet ownership and signs and symptoms present in 370 schoolchildren (3-12 years old) of Argentina. The positive serology for toxocariasis was 19.5%, associated with eosinophilia and possession of cats as pets. The stool testing revealed 70.0% of parasitized children. Its frequency was 44.9% helminthes and 53.5% protozoan resulting single significant presence of protozoa in children aged 10-12 years. The species were: Blastocystis hominis (45.7%), Enterobius vermicularis (43.2%), Giardia intestinalis (16.2%), Hymenolepis nana (2.4%), Ascaris lumbridoides (1.6%) and Trichuris trichiura (0.3%). The survey showed 13.0% of children with sporadic abdominal pain and 13.5% with pruritus ani. The results indicate relationship between positive serology and eosinophilia compatible with a clinical aspect of covert toxocariasis self-limiting, associated with cats ownership; in school children from our region who also have high frequency of intestinal parasitoses.

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.

Effect of Paecilomyces lilacinus on the viability of oncospheres of Taenia hydatigena.

Paecilomyces lilacinus (Thom) Samson is a saprophytic hyphomycete from the soil with biological activity on helminth eggs. We evaluated the influence in vitro of P. lilacinus on the viability of the oncospheres from Taenia hydatigena, a parasite cestode of dogs and sheep. The eggs were exposed to the fungus strain in sterile distilled water and observed by light microscopy at days 4, 7 and 14 post-inoculation, and the viability was evaluated. The viability found in the exposed P. lilacinus oncospheres was significantly different in all observations. P. lilacinus exercised a negative biological activity on T. hydatigena eggs in vitro.

[Purification and breaking techniques for cysts of Giardia spp]. / Técnicas de purificación y ruptura de quistes de Giardia spp.

The purpose of this study was to optimize and evaluate the purification techniques, isolation and breaking of cysts of Giardia spp from fecal samples to isolate DNA. Filtrated fecal samples were tested in 3 purification techniques: Telleman solution, sucrose and Telleman plus sucrose. The sucrose solution let us to isolate the cysts with less detritus. The cleaned cysts were splited in 3 techniques to test the breaking: osmotic shock and heat, chemistry degradation and thermic shock, enzymatic action and mechanic effect. Only the last method was successful and showed bands in agarose gel. The result of this study shows a routine and common method which could be used in the previous steps to the PCR technique for the genotypification of these parasites.

Técnicas de purificación y ruptura de quistes de Giardia spp / Purification and breaking techniques of cysts of Giardia spp

El objetivo de este trabajo fue optimizar y evaluar las técnicas de purificación, aislamiento y ruptura de quistes de Giardia spp a partir de heces formoladas para la obtención de ADN. La materia fecal filtrada fue sometida a 3 técnicas de purificación, utilizando soluciones de formol-éter, sacarosa y formol-éter más sacarosa. La solución de sacarosa permitió aislar los quistes con menos detritos. Los quistes purificados fueron tratados con 3 técnicas para la ruptura de los mismos: shock osmótico y calor, degradación química y shock térmico, acción enzimática y efecto mecánico. Solamente con la técnica de shock térmico, acción enzimática y efecto mecánico se observaron bandas fluorescentes en geles de agarosa. Los resultados de este trabajo permiten contar con una metodología de rutina, simple, que podría ser usada en los pasos previos a la técnica de PCR para la genotipificación de este parásito.

The purpose of this study was to optimize and evaluate the purification techniques, isolation and breaking of cysts of Giardia spp from fecal samples to isolate DNA. Filtrated fecal samples were tested in 3 purification techniques: Telleman solution, sucrose and Telleman plus sucrose. The sucrose solution let us to isolate the cysts with less detritus. The cleaned cysts were splited in 3 techniques to test the breaking: osmotic shock and heat, chemistry degradation and thermic shock, enzymatic action and mechanic effect. Only the last method was successful and showed bands in agarose gel. The result of this study shows a routine and common method which could be used in the previous steps to the PCR technique for the genotypification of these parasites.

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.

Distribution of intestinal parasitoses in relation to environmental and sociocultural parameters in La Plata, Argentina.

Environmental parameters influencing the distribution of parasite species in three neighbourhoods of differing socioeconomic conditions in La Plata, Argentina were analysed. Coproparasitological screenings were performed in children up to 14 years old from a marginal zone (100), a suburban neighbourhood (101), and an urban area (91) in 1999--2000. The presence of parasite species in environmental samples (water and soil) and the degree of association among parasite communities was documented and evaluated. The prevalence of infection in each population was 73.0%, 54.4% and 35.2%, respectively. The frequencies of helminths and pathogenic protozoa were both higher in the marginal zone, where sanitary and environmental conditions were significantly inferior compared with the other zones. The high prevalence of intestinal parasites in this infantile population was related to parasitic contamination of the soil and water sources in addition to deficient sanitary and sociocultural conditions. Calculation of an equitability index revealed that the specific richness was less equitable once socioeconomic conditions and hygienic practices were improved. This study demonstrates the need to implement management practices for the control of intestinal parasitoses in accordance with the environmental and sociocultural characteristics of a given ecosystem.

Clinical status and parasitic infection in a Wichí Aboriginal community in Salta, Argentina.

In a study, carried out in 2000, of the clinical and parasitological status of a Wichi Aboriginal community living in the suburbs of Tartagal, northern Salta, Argentina, 154 individuals were screened for parasitic infections. Ninety-five faecal samples were also obtained from the same population. Ninety-three percent of the subjects were positive for 1 or more of the parasites investigated by direct test and 70.5% of them had parasitic superinfection. The most frequent helminths were Strongyloides stercoralis (50.5%) and hookworm (47.4%). We found low reinfection rates and a long reinfection period after treatment and provision of safe water and sanitation. Serum reactivity of these patients was analysed by enzyme-linked immunosorbent assay and indirect immunofluorescent assay and 22.1% of them had anti-Toxocara antibodies, 16.2% were positive for a complex antigen of Leishmania braziliensis, 29.9% were positive for a complex Trypanosoma cruzi antigen, and 17.5% were positive for a specific Trypanosoma cruzi antigen, Ag 163B6/cruzipain.

Biological interaction between soil fungi and Toxocara canis eggs.

Fungi from the soil of public areas in La Plata, Argentina were isolated and evaluated for their biological interaction with Toxocara canis eggs in vitro. We isolated and identified two fungal species: Fusarium pallidoroseum and Mucor hiemalis. Each species was co-cultured with T. canis eggs in sterile distilled water. The samples were observed by light and scanning electron microscopy (SEM) at days 4, 7 and 14 post-inoculation. Under the conditions of our experiments, F. pallidoroseum exhibited a high ovicidal activity on T. canis eggs, whereas M. hiemalis exhibited no such effects.

Biological activity of Paecilomyces genus against Toxocara canis eggs.

Saprophytic soil fungi can exert ovicidal and ovistatic effects on helminths with differing degrees of efficiency. The representatives of such fungi from temperate regions, Paecilomyces lilacinus (Thom) Samson and P. marquandii (Masse) Hughes, exhibit recognized ovicidal activity on some nematodes. We evaluated the action in vitro of P. lilacinus and P. marquandii on the zoonotic canine roundworm eggs of Toxocara canis. Eggs exposed and unexposed to fungal samples were observed by both light and scanning electron microscopy on days 4, 7 and 14 post-inoculation. Ovicidal activity of P. lilacinus on T. canis eggs was considered to be high and that of P. marquandii to be intermediate.

Anthelmintic efficacy of tinidazole against the progression of Toxocara canis larvae to the brain in mice.

The anthelmintic effect of tinidazole (100 mg/kg per day for 3 successive days) was tested in male Swiss CF-1 mice infected with second-stage Toxocara canis larvae at challenge doses of 250, 500, 1000, and 1500 embryonated eggs per mouse. The drug was given orally on days 3-5 postinfection (p.i.) to one-half of the animals, and all mice were killed on day 40 p.i. The number of larvae recovered from each mouse's brain and skeletal muscle was then scored in both groups. Tinidazole yielded a highly significant reduction in the total recovery of larvae from the test animals' brains at the second and third inoculum levels but no statistically significant reduction at the highest larval dose as compared with the values obtained in the untreated control animals.

[Asthma and covert toxocariasis]. / Asma y toxocarosis encubierta.

The relationship between asthma and covert toxocariasis was studied in 38 patients with asthma and 44 control individuals (without asthma). Inclusion/exclusion criteria were determined. An ELISA test based on the detection of Anti-Toxocara canis (E/S antigen) serum immunoglobulin G (Ig G) and E (Ig E) was determined in both groups. Ordinary allergens and E/S antigen of T. canis injections were used to evaluate cutaneous reactivity. The seroprevalence in patients with asthma was 68.42%, and in the control individuals was 13.63%. This difference was significant. The percentage of asthmatic patients with two antitoxocara antibodies was 26.31% and 4.54% in control individuals. All asthmatic patients with antitoxocara IgE had cutaneous reactivity to Ag E/S. We conclude that the asthmatic patients with IgE and IgG antitoxocara suffer a covert toxocarosis.

[Intestinal parasite infections in a periurban community from the Province of Buenos Aires, Argentina]. / Estudio de las infecciones por enteroparásitos en una comunidad periurbana de la provincia de Buenos Aires, Argentina.

A survey for intestinal parasites was performed on 38 individuals within the urban area of La Plata City (Province of Buenos Aires, Argentina). This community is composed of brick-factory workers who also live in the factory premises. An analysis for intestinal parasites was done on fecal samples collected serially and by means of anal swabs and thereafter preserved in formol solution. At the same time, the occurrence of the parasites under study as well as that of commensal organisms was investigated in water and soil samples within the factory environs. Information was also obtained from the members of this community as their age, sex, birthplace, and recent travels, either abroad or to the interior of Argentina. The prevalence of the pathogens and commensal parasites was 89.5%. The frequency of protozoans and helminths was: G. lamblia 26.3%, B. hominis 65.8%, A. lumbricoides 7.9%, H. nana 2.6%, Uncinaria sp. 7.9%, S. stercoralis 2.6% and E. vermicularis 42.1%. None of these parasite or commensal organisms were present in the water samples investigated. Four out of 20 soil samples analyzed contained parasitic elements: T. canis eggs (one), G. lamblia cysts (two) and A. lumbricoides eggs (one). These results indicated that most important factors causing such a high prevalence of coproparasites were the poor conditions of personal and community hygiene in combination with the frequent travels to the north and the northeast of the country, regions which are endemic parasitic areas. The implementation of programs on health education and communal sanitation would contribute in the control of this health problem.

Relationship between parasitical inoculum and immunological parameters in experimental toxocariasis.

Swiss female mice were inoculated with different infective doses of Toxocara canis eggs to evaluate the percentage of recuperated larvae in different organs and immunological parameters such as spleen index (SI), liver index (LI) and lung index (LuI) and blood eosinophilia during 3 weeks post infectionem (p.i.) with only one challenge. It was found that T. canis larvae arrived at the liver between 10 and 15 hours p.i. by the food-fishhook technique. When the inoculum was more than 200 eggs, there was a reinvasion of liver and lungs at 504 hours p.i. The larval arrival at the brain was delayed in an inverse relationship to the inoculum but the percentage of recovery was about 7 and 8%. The organic indexes were in a direct relationship with the inoculum size and the increase in eosinophilic levels in massive infections (2000 eggs) was in agreement with a strong immune response.

[Frequency of finding helminths eggs in canine stool samples collected in public places in the La Plata city, Argentina]. / Frecuencia de hallazgo de huevos de helmintos en materia fecal canina recolectada en lugares públicos de la ciudad de La Plata, Argentina.

A study was carried out in order to determine the level of contamination with helminth eggs in different sectors of the city of La Plata, Argentina. A total of 351 fecal pools were collected from streets (328) and parks and public places (23) of this locality. Of these fecal pools, 117 (33.3%) contained eggs of at least one helminth species. The overall frequencies found were: Uncinaria sp. 16.0%, Trichuris vulpis 9.7% and Toxocara canis 10.5%.