Juan Angel Basualdo

A wide diversity of zoonotic intestinal parasites infects urban and rural dogs in Neuquén. Patagonia, Argentina

The presence of parasites was investigated by the examination of 1944 dog faecal samples collected from urban (n=646) and rural (n=1298) areas of the province of Neuquén, Patagonia, Argentina. Parasitic agents (PA) were found in 37.86% of samples. A total of 15 different PA were detected, including Toxocara canis (16.35%), Taenia spp./Echinococcus spp. (12.65%), Trichurisvulpis (6.06%), Giardia spp. (1.29%), Toxascaris leonina (0.56%), Ancylostomacaninum (0.41%), Dipylidium caninum (0.31%), Diphyllobothrium spp. (0.10%), among others. Several of these PA are recognized as zoonotic agents. Therefore, the results of this investigation revealed that local population is exposed to a broad spectrum of zoonotic parasites by means of environmental contamination with dog faeces. Prevalence of PA was slightly higher in rural (40.06%) than in urban (33.44%) locations. Distribution of groups of PA (cestodes, nematodes, and protozoa) showed statistical differences between both habitats. Prevalence of cestodes (18.18%) and protozoa (11.86%) was significantly higher in the rural environment than in urban areas and nematodes (29.10%) were more frequent in urban locations. Infection of dogs with Linguatula serrata and Cryptosporidium sp. was demonstrated for the first time in Neuquén. Rural dogs of the study area are under hydatic disease control program, which includes treatment with praziquantel every 6 weeks; thus, the finding of high level of cestode infection in these areas is of great relevance. The epidemiology of zoonotic parasitic infections in urban and rural dogs showed different patterns and, in consequence, different control measurements should be applied in each location.

Intestinal parasitoses and environmental factors in a rural population of Argentina, 2002-2003

We evaluate the prevalence of intestinal parasites in 504 people and the degree of association between environmental variables and parasites found in population, soil and water in a rural area of Argentina during 2002-2003. A structured survey was used to evaluate the environmental variables and fecal-human, soil and water samples were analyzed. The prevalence of parasites was 45.4%. Most prevalent protozoa were Blastocystis hominis (27.2%) and Giardia lamblia (6.9%), while the most prevalent helminth was Ascaris lumbricoides (3.8%). The analyzed environmental variables showing association (p < 0.05) with presence of parasites in population were: cardboard-tin or wooden house, dirt floor, home or communal water pump, faucet outside the house or public faucet and cesspool or latrine. Parasite forms were found in 82.3% of the soil samples and in 84.2% of the water samples. In both samples we found parasites that were also found in people. In this study we have found deficient sanitary conditions associated with presence of parasites in population and we have evidenced that contaminated soil and water were the source of these parasites.

First genotyping of Giardia lamblia from human and animal feces in Argentina, South America

The purpose of this study was to investigate the genotypes of Giardia lamblia from human and animal feces and their epidemiological and clinical characteristics in Argentina, South America. Seventy isolates, 60 from humans (adults and children), eight from dogs and two from cows were processed by polymerase chain reaction-restriction fragment length polymorphism. Data corresponding to demographic, socio-cultural and environmental variables and presence/absence of signs/symptoms were collected. The triosephosphate isomerase gene was amplified from 43 (71.66%) of the 60 human fecal samples. Among these, 3/43 (6.98%) were genotype AII and 40/43 (93.02%) were genotype B. Assemblage AII was detected in three children who lived together in a shantytown and they were oligosymptomatic and none had diarrhea. This genotype was not found in animals. Genotype B showed a high prevalence in both adults and children. It was also found in polysymptomatic people, many of whom presented diarrhea. It was also found only in one dog. The present study represents the first contribution to the knowledge of G. lamblia genotypes in Argentina.

Related factors to human toxocariasis in a rural community of Argentina

The objective of this study was to evaluate the relationship between toxocariasis frequency and demographic, environmental, sanitary variables, eosinophylia, and other intestinal parasites in a rural population of Argentina. Serological examination of 100 individuals was carried out by using ELISA technique for the detection of anti-toxocara antibodies. Eosinophiles in peripheral blood, presence of intestinal parasites, and demographic, environmental, and socio-cultural data were evaluated. Eighty-one feces samples of dogs belonging to the studied people were analyzed to detect eggs of Toxocara canis. Thirty of them were from 30 dogs and 51 were pools from dog feces. Samples of dirt from around the homes (n: 47) and from public park (n: 4) were taken. To determine the associations, the c(2) and Fisher tests were used. The seroprevalence was 23%. Eosinophilia in peripheral blood was detected in 86.95% seropositive individuals and in 37.66% seronegative individuals (p < 0.001, OR = 11.03). Of the 23 people with positive serology, 69.56% had at least one intestinal parasite. All individuals with positive serology had dogs in their homes. Among the dog owners there was a significant association between the presence of anti-toxocara antibodies and home flooding. Eggs of T. canis were detected in the feces of 5/81 dogs and three of these dogs belonged to individuals with positive serology. Eggs of Toxocara spp. were found in 41.17% of the dirt samples, eight of which came from the area surrounding the homes of individuals with positive serology (p = 0.032; OR = 4.36). Taking into account all the variables influencing the frequency of toxocariasis in this population, the implementation of Public Health programs specifically focused on anti-parasitic treatment of dogs is recommended.

Molecular characterization of Echinococcus isolates indicates goats as reservoir for Echinococcus canadensis G6 genotype in Neuquén, Patagonia Argentina

Human cystic echinococcosis is a highly endemic zoonotic disease in the province of Neuquén, Patagonia Argentina, although a hydatid control programme has been carried out since 1970. Human infection due to Echinococcus canadensis (G6 genotype) is frequent in Neuquén. However, the reservoir for this species remains undetermined in a region where camels are absent. We investigated the fertility, viability and molecular epidemiology of hydatid cysts obtained from local goats, pigs and sheep in order to identify the possible reservoirs of E. canadensis (G6). We also analyzed isolates from infected dogs. A total of 67 isolates were identified by the DNA sequencing of the mitochondrial cytochrome c oxidase subunit 1 gene. Cysts from sheep (n=16), goats (n=23) and pigs (n=18) and adult worms from 10 infected dogs were analyzed. The fertility of the hydatid cysts was 78.6%; 90.4% and 94.4% for sheep, goats and pigs, respectively. We detected E. canadensis (G6) in 21 of 23 goat samples and in 1 dog isolate, E. canadensis (G7) in all the pig isolates, E. granulosus sensu stricto (G3) in 1 sheep and the G1 genotype in 15 sheep, 2 goats and 9 dog samples. The G1 haplotypes included the common sheep strain sequence and 2 microvariants of this sequence. E. granulosus sensu stricto (G3) is described for the first time in South America. We conclude that goats act as reservoir for E. canadensis (G6) in Neuquén, and that control strategies may have to be adapted to local molecular epidemiology to improve the control of parasite transmission.

Screening of the municipal water system of La Plata, Argentina, for human intestinal parasites.

The La Plata River, though severely contaminated by intestinal parasites through the discharge of tons of crude fecal material from a main sewage channel, nevertheless provides drinking water to two-thirds of La Plata, Argentina, after conventional purification at a processing plant. With intestinal parasitosis being endemic here, we investigated the importance of this water in transmitting such pathogens to the citys populace by means of standard methodology for sample acquisition and processing involving filter-concentration of waterborne particulates. Of 14 tap-water samples collected from the distribution network, 12 pertained to four zones (A-D) within the city center; while the remaining 2 were obtained near the processing plant, 15 kilometers outside the city. Although parasites were found within the samples derived from the four urban zones, none were detected in the specimens obtained near the plant. The four downtown areas differed from each other as to the quantity and nature of the parasites present in their water: whereas zones A and B registered similar lower levels of contaminants, C and D exhibited higher values significantly different from the former two and from each other. Given an average parasite count/l citywide of 0.38 and a probability of encountering a parasite within 11 of water of 0.32, the municipal network is seen to contribute to the transmission of intestinal parasites. A routine system of water-quality control is therefore needed throughout the city along with the establishment of infrastructures for locating and eliminating peripheral sources of contamination.

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.

Presencia de parásitos intestinales en paseos públicos urbanos en La Plata, Argentina

With the aim of recovering and identifying parasitic elements we studied soil samples from allpublic place of La Plata, Argentina (urban area). We surveyed 23 places during March and April,2000 and at the time of study we measured both the pH and moisture content of each sample taken.We detected 552 parasitic elements, with 98 corresponding to protozoon cysts, 106 to helmintheggs and 348 to nematode larvae. We conclude that the soils in surveyed public places arecontaminated with parasites of animal as well as human origin.

Cryptosporidium infection in calves from a rural area of Buenos Aires, Argentina

Dairy calves less than 1 month of age are commonly infected with Cryptosporidium spp. The objective of the present study was to evaluate the prevalence of Cryptosporidium spp. among dairy calves <or=30 days old, with and without diarrhoea, in a rural area of Buenos Aires, Argentina. A total of 280 calves were studied. For each calf a single faecal sample was obtained and processed by water-ether concentration. The microscopic search was carried out using a modified Ziehl-Neelsens acid fast method. The population was stratified according to days of life. The samples were classified according to macroscopic characteristics. The intensity of infection was estimated semiquantitatively according to the average number of oocysts in 20 randomly selected fields observed at 1, 000 x. Analysis of a single sample of each 280 calves revealed that 48 calves eliminated oocysts. The overall prevalence of cryptosporidial infection was 17%. The analysis of the macroscopic characteristics of the faeces of all the studied calves showed that 57.1% were diarrhoeic. The 100% of the infected calves were <or=14 days old. The prevalence according to age group was: 37.5% for <or=7 days, and 21.4% for >or=8<or=14 days. Both normal and diarrhoeic faeces with blood were negative for Cryptosporidium spp. The 37.5% of diarrhoeic faeces without blood were positive, showing a presence of mucus of 83.3%. The 66.7% of samples with mucus showed an average of 10 oocysts/field. The relationship between intensity of infection and age group showed that 66.7% of positive samples from calves <or=7 days old, presented an average of >10 oocysts/field. This study shows that Cryptosporidium spp. is one of the causes of calf neonatal diarrhoea in a rural area of Buenos Aires, Argentina. The highest intensity of infection reported for the <or=7-day-old group demonstrates that these animals are, from an epidemiological point of view, an important source of contamination of water and soil of the area.

First report of Enterocytozoon bieneusi from dairy cattle in Argentina.

Fecal specimens were obtained from a total of 70 dairy calves less than two months old on 11 municipalities in Buenos Aires, Argentina. After removal of fecal debris by sieving and sucrose flotation, specimens were subjected to PCR to detect the presence of Enterocytozoon bieneusi. PCR revealed a 14.3% of prevalence for E. bieneusi with 10 positive calves from 7 municipalities. Gene sequence analysis conducted in all samples positives by PCR revealed the presence of six genotypes; four previously reported in cattle as well as humans (D, I, J, and BEB4), one never reported in cattle before but previously reported in humans (EbpC), and one novel genotype (BEB10). These results constitute the first molecular characterization of E. bieneusi in Argentina, and suggest a potential risk of zoonotic transmission in this area.