Seroprevalence of toxocariasis in blood donors of Gualeguaychú, Argentina

Seroprevalence of human toxocariasis in Latin America and the Caribbean: a systematic review and meta-analysis

Introduction

The current study aimed to quantitatively synthesize available evidence regarding the seroprevalence of human toxocariasis in Latin America and the Caribbean.

Methods

A systematic research involving six electronic databases was conducted using a research strategy that combined MeSH terms with free terms. Article selection and information extraction were performed using a double and independent approach. The Newcastle-Ottawa tool was used to assess the risk of bias in the included articles. The meta-analysis used the random-effects approach, with subgroup analysis and sensitivity analysis for risk of bias also being performed.

Results

We included 101 articles with a total of 31,123 participants. The studies were conducted between 1990 and 2022, with Brazil accounting for the largest number of studies (n = 37). The overall seroprevalence of human toxocariasis was 31.0% (95% CI: 27.0-35.0%, I2 = 99%). The prevalence of the main characteristics observed in seropositive patients were as follows: ocular toxocariasis (30.0%), asymptomatic (26.0%), and presence of dogs at home (68.0%). In addition, the seroprevalence was lower in studies including only adults than in those including children or both. In contrast, no differences in seroprevalences were found between studies conducted in the community and hospital.

Conclusion

The overall seroprevalence of human toxocariasis in Latin America and the Caribbean was high. Notably, our findings showed that the seroprevalence was increased among populations who kept a dog at home but was decreased in populations comprising only adults. Our findings can be used to establish epidemiological surveillance strategies for the prevention and early identification of toxocariasis.

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.

Anti-Toxocara spp. antibodies in an adult healthy population: serosurvey and risk factors in Southeast Brazil

OBJECTIVE

To evaluate the frequency of anti-Toxocara spp. antibodies in an adult healthy population.

METHODS

The study was performed by interviewing 253 blood donors, from 19 to 65 years of age, in a hematological centre in Presidente Prudente, São Paulo, southeast Brazil. A survey was applied to blood donors in order to evaluate the possible factors associated to the presence of antibodies, including individual (gender and age), socioeconomic (scholarship, familial income and sanitary facilities) and habit information (contact with soil, geophagy, onycophagy and intake of raw/undercooked meat) as well as the presence of dogs or cats in the household. ELISA test was run for detection of the anti-Toxocara spp. IgG antibodies. Bivariate analysis followed by logistic regression was performed to evaluate the potential risk factors associated to seropositivity.

RESULTS

The overall prevalence observed in this study was 8.7% (22/253). Contact with soil was the unique risk factor associated with the presence of antibodies (P=0.017 8; OR=3.52; 95% CI=1.244-9.995).

CONCLUSIONS

The results of this study reinforce the necessity in promoting preventive public health measures, even for healthy adult individual, particularly those related to the deworming of pets to avoid the soil contamination, and hygiene education of the population.

The infectivity and antigenicity ofToxocara caniseggs can be retained after long-term preservation

Suspensions of fertilized eggs of Toxocara canis were mixed with 2% neutral formalin and preserved at 4 degrees C. When, after storage for 0, 12, 18, 21 and 24 months, samples of the eggs were incubated at 30 degrees C for 12 days, 96.8%, 92.6%, 74.1%, 51.0% and 19.3% of the eggs in the samples were found to embryonate. The embryonated eggs produced from the fertilized eggs preserved (in 2% neutral formalin at 4 degrees C) for 0, 12, 18 and 21 months were then tested for their infectivity to BALB/c mice, each mouse being given 800 embryonated eggs. The numbers of larvae recovered from the mice and the sites from which they were recovered, 2 or 14 days post-infection, appeared unaffected by the length of storage of the eggs. The infected mice all had similar eosinophil counts in their peripheral blood and similar serum titres of Toxocara-specific IgM and IgG antibodies, and cultures of their spleen cells produced similar amounts of interleukin-4, interleukin-5 and interferon-gamma when stimulated with concanavalin A. The results of SDS-PAGE indicated that egg preservation for at least 21 months had no effect on the excretory-secretory antigens in samples of medium from cultures of infective larvae released from the eggs. In summary, at least 50% of the fertilized eggs preserved in 2% neutral formalin at 4 degrees C for 21 months could fully embryonate and then had the same infectivity and antigenicity as embryonated fresh eggs.

In vitro and in vivo effects of Enterococcus faecalis CECT7121 on Toxocara canis

The aim of the present paper was to evaluate the larvicidal effect of Enterococcus faecalis CECT7121 (Ef7121) on the Toxocara canis cycle both in vitro and in vivo. For the in vitro experiments, T. canis larvae were incubated with the supernatants of Ef7121 (EI) and mutant Ef7121 (EIm), in a pre-culture of Ef7121 (EII) and in a fresh culture with Ef7121 (EIII) and the Ef7121 mutant strain (EIIIm). The viability of the larvae was calculated after a 48 h incubation. A significant reduction of the viability of T. canis larvae was observed in EI, EII and EIII. A decrease of this inhibitory effect was observed in EIm and EIIIm (p = 0.008). In the in vivo experiments, mice were orally inoculated with three doses of Ef7121. To study the probiotic persistence in the intestine, the animals were sacrificed every four days and their intestines were dissected. The initial average bacterial levels were 9.7 x 10(4) for Ef7121 (colony forming units/g). At the end of the assay the levels were 1.46 x 10(4). No bacterial translocation was detected in mesenteric lymphatic nodules and spleen. Ef7121 interference with the biological cycle was evaluated in mice challenged with T. canis. The interference was significant when the mice were challenged with probiotic and T. canis simultaneously (p = 0.001), but it was not significant when the challenge was performed 15 days after administration of the bacterial inoculum (p = 0.06). In conclusion, Ef7121 possessed in vitro and in vivo larvicidal activity.

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.

Frequency and risk factors for toxocariasis in children from a pediatric outpatient center in southeastern Brazil

To estimate the frequency of anti-Toxocara sp. antibodies, and evaluate factors associated with this infection, sera from 242 male and female children, aged from one to fifteen years old, attended at the Hospital of the Federal University of Uberlândia, Minas Gerais State, Brazil, were analyzed by ELISA. Information on the patients was collected and registered using an investigative questionnaire, and details on possible clinical alterations were obtained from the medical charts of 187 patients. Of a total of 242 samples, 21 (8.7%) were positive for anti-Toxocara sp. antibodies. The presence of dogs and cats and the school variable (place of contact), appeared to be significantly associated (p < 0.05) with a positive serology. Respiratory symptoms and eosinophil counts greater than 20% also showed a positive statistical correlation with a positive serology for Toxocara sp.. Factors such as sex and age, and symptoms like headache, stomach ache, convulsive crises and anemia were not associated with toxocariasis.

An epidemiological study of gastrointestinal parasites of dogs from Southern Greater Buenos Aires (Argentina): age, gender, breed, mixed infections, and seasonal and spatial patterns

A total of 2193 fecal samples from owned dogs were collected during the 2003-2004 period in Southern Greater Buenos Aires, and were evaluated for the presence of intestinal parasites by a flotation-centrifugation method. The overall prevalence was 52.4%, and the 11 species found were: Ancylostoma caninum (13%), Isospora ohioensis complex (12%), Toxocara canis (11%), Trichuris vulpis (10%), Sarcocystis sp. (10%), Giardia duodenalis (9%), Isospora canis (3%), Hammondia-Neospora complex (3%), Dipilydium caninum (18 cases), Cryptosporidium sp. (5 cases), and Toxascaris leonina (1 case). There was no significant difference in the overall prevalence between genders (female = 50.4%, male = 54.6%), and breeds (pure = 52.3%, mixed = 53%), but prevalence in puppies (<1 year) was higher than in adult dogs (62.7% versus 40.8%, respectively). Only the prevalence of A. caninum differed between genders, with higher values for males. The prevalences of six of the parasite species showed a decreasing trend with increasing host age, and an inverse pattern was found for two other species. The prevalences of three protozoa were significantly higher in pure-breed dogs, and those of two nematodes were significantly higher in mixed-breed dogs. The prevalences of T. canis, A. caninum, and T. vulpis were spatially heterogeneous with a clear Southwest-Northeast gradient. Only prevalences of Sarcocystis sp. and G. duodenalis showed seasonal variation. The frequency distribution of the number of species per fecal sample did not differ from a random distribution. Results obtained throughout the world were discussed.

[Toxocariasis in adults]

PURPOSE

Toxocariasis is a widespread zoonotic parasitosis that is frequent in France. It is due to the presence of larvae of roundworms belonging to the genus Toxocara in the human body. Clinical signs are often non-specific. The disease can be asymptomatic or can lead to death. Toxocariasis can be thought of because of clinical signs or presence of hypereosinophilia, but the diagnosis is made by specific serology. Since there is no consensus to date regarding treatment, prevention is of paramount importance.

CURRENT KNOWLEDGE AND KEYPOINTS

Recent studies point out the frequency of this parasitic disease that is often asymptomatic. The serological diagnosis remains the main tool for the diagnosis of toxocariasis.

FUTURE PROSPECTS AND PROJECTS

Further studies on toxocariasis should focus on the prevalence of this disease in French population regarding the probability of infection: living in the countryside, food habits, hygiene and presence of dogs in the neighborhood. Tools of the biological diagnosis (mainly serological techniques) should be improved, but, especially, studies should focus on the evaluation of specific treatment in order to give unquestionable guidelines on this point.

Human toxocariasis: frequency of anti-Toxocara antibodies in children and adolescents from an outpatient clinic for lymphatic filariasis in Recife, Northeast Brazil

In a transversal study on a sample of 386 children and adolescents from an outpatient clinic for filariasis in Recife, Northeast Brazil, the frequency of anti-Toxocara antibodies and its relation to age, gender, number of peripheral eosinophils, Wuchereria bancrofti microfilariae and intestinal helminths was determined. The total anti-Toxocara IgG antibody frequency was 39.4%, by ELISA technique. The difference in frequency between males (40.1%) and females (37.6%) was not statistically significant. The 6 to 10-year-old subset presented the highest frequency of anti-Toxocara antibodies (60%), and within this age group there was a statistically significant male bias. There was also a significant association between the number of eosinophils and the presence of anti-Toxocara antibodies. Intestinal parasite frequency was 52.1%, but no association was found between this data and the presence of anti-Toxocara antibodies. In the present sample, 42.2% of the patients were Wuchereria bancrofti carriers, however, again this was not associated with the presence of anti-Toxocara antibodies. In conclusion, anti-Toxocara antibodies were highly prevalent in this sample. The present data show that there is no cross correlation between anti-Toxocara IgG antibody and the presence of intestinal helminths and filariasis.

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.

Human toxocariasis: a seroepidemiological survey in the municipality of Campinas (SP), Brazil

The occurrence of human Toxocara infection was evaluated in three neighborhoods of the periphery of the Campinas municipality (Jardim Santa Mônica, Jardim São Marcos and Jardim Campineiro) in 1999. Forty residences and 138 residents were randomly selected by drawing lots and were submitted to a seroepidemiological survey, which included blood collection for the immunoenzymatic detection (ELISA) of anti-Toxocara antibodies and a blood count, and the application of a semi-structured questionnaire for the evaluation of epidemiological data. Significant levels of anti-Toxocara antibodies were detected in 23.9% of the 1999 samples. No significant difference in the frequency of infection according to age was observed. Environmental contamination with Toxocara eggs was observed in 12.3 and 14.0% of 57 soil samples collected in the same region in December 1998 and July 1999, respectively. Univariate analysis and multiple logistic regression of the data obtained from the questionnaires and of the results of the serological tests, suggest a significant influence of socioeconomic variables on the frequency of human infection with Toxocara under the conditions prevalent in the study area.