Seroprevalence of Toxocara spp. in a rural population in Central African Gabon

One health approach to toxocariasis in quilombola communities of southern Brazil

BACKGROUND

Toxocariasis has been listed among the most neglected parasitic diseases worldwide, with approximately one fifth of the global population exposed, particularly those living under poverty. In Brazil, communities of descendants of enslaved blacks (quilombola) have historically had some of the highest rates of vulnerability and poverty, characterized by lack of health assistance, poor quality of life, and nutritional insecurity.

METHODS

A cross-sectional sampling of quilombola individuals living in four communities of southern Brazil, as well as their dogs and the soil, was carried out from December 2021 to March 2022. Sociodemographic and other information such as water source, alimentary habits, and dog and cat ownership were gathered using a semi-structured questionnaire for assessing toxocariasis risk factors. Human serum samples were tested by ELISA for anti-Toxocara spp. IgG antibody detection was carried out on dog feces and hair, and soil samples were surveyed for presence of Toxocara spp. eggs.

RESULTS

Overall, 172/208 individuals (82.7%, 95% CI = 77.0-87.2) were seropositive, the highest seroprevalence rate to date in Brazil. Male gender (P = 0.029), educational level (P = 0.026), and drinking water source (P = 0.043) were associated with seropositivity by univariate analysis. Final logistic regression revealed increased odds (P = 0.017, OR = 7.6, 95% CI = 1.5-42.7) to have seropositivity in individuals > 50 years old (< 10 years old). As expected, individuals with soil contact were more likely seropositive (P = 0.038, OR = 4.4, 95% CI = 1.1-18.8). Although retrieved in only 5/96 (5.2%) dog feces, Toxocara spp. eggs were found in 18/60 (30.0%) soil samples.

CONCLUSIONS

The high vulnerability and seroprevalence observed in quilombola communities clearly demand a One Health approach for detection, monitoring, and prevention of infection by Toxocara spp. in both human and dog populations.

One health approach to toxocariasis in Brazilian indigenous populations, their dogs, and soil contamination

Introduction

Although socioeconomic vulnerability and lifestyle factors may contribute to the transmission of Toxocara spp., no study has investigated indigenous populations in Brazil using the One Health approach.

Methods

Accordingly, this study assessed anti-Toxocara spp. antibodies in Brazilian indigenous people and healthcare professionals by enzyme-linked immunosorbent assay. Presence of Toxocara spp. eggs (feces and hair) in dogs as definitive hosts and in soil samples of the indigenous communities were also recovered and molecularly investigated.

Results

Overall, 342/463 (73.9%) indigenous individuals and 46/147 (31.3%) non-indigenous healthcare professionals were seropositive for Toxocara spp. In addition, T. canis eggs were retrieved from 9/194 (4.6%) dog fecal samples and 4/204 (2.0%) dog hair samples, mainly from the Paraná State communities (3/42; 7.1%). Soil contamination was observed only in the Paraná State communities (36/90; 40.0%), with the molecular detection of T. canis. River water consumption was also associated with indigenous seropositivity (Odds ratio, 11.4).

Discussion

Indigenous individuals in Paraná State communities were 2.72-fold more likely to be seropositive than those in São Paulo State, likely due to a lack of sanitary infrastructure. In this scenario, a primarily soil-transmitted disease may also have become waterborne, with embryonated eggs probably spread to water supplies by rain. Full-time healthcare professionals in daily contact with indigenous communities were 9.2-fold more likely to be seropositive than professionals who visited sporadically, suggesting exposure to Toxocara spp. during their work and raising health concerns. In addition, the findings herein showed a significantly higher seroprevalence in indigenous people than in healthcare workers (χ2 = 85.5; p < 0.0001), likely due to overtime exposure to Toxocara spp. In conclusion, Brazilian indigenous communities are highly exposed to toxocariasis, with poor infrastructure and contact with contaminated river water as associated risk factors and a higher risk of infection in healthcare professionals working full-time in these communities.

Molecular investigation of Toxocara infection from the serum of people living with HIV in Alborz, Iran

BACKGROUND

Toxocara infection is one of the most common neglected infections of poverty and a helminthiasis of global importance. Traditional diagnostic methods such as antibodies detection in serum samples are limited due to cross-reactivity and poor sensitivity. The use of molecular base methods for diagnosis of Toxocara infection in Iran has not been fully explored. The purpose of the current study was to estimate the prevalence of Toxocara infection from serum samples of people living with HIV in Alborz province, Iran using serological and molecular methods.

METHODS

Blood samples were collected from 105 people living with HIV. Epidemiological data of participant were obtained through a structured questionnaire to investigate the risk factors. Patients CD4⁺ T cell count were recorded. Anti-Toxocara IgG antibodies were detected by ELISA, with a cut-off point of 11. PCR was performed to detect genetic material of Toxocara species in the serum samples.

RESULTS

The mean CD4⁺ count in HIV-infected individuals with positive toxocariasis serology was 255.1 ± 21.6 cells/µL. Seropositivity for Toxocara species was observed in 12/105 (11.4%) people living with HIV. Three samples gave positive results on PCR analysis. Based on the data, a statistically significant relationship was found between anti-Toxocara IgG antibodies seropositivity and underlying conditions (p = 0.017). No significant statistical association was observed between seropositivity for Toxocara and gender, age, exposure to domestic animals or pet keeping, education levels, and occupation (p > 0.05). The findings of PCR confirmed Toxocara DNA in 3/12 (25.0%) serum samples.

CONCLUSION

These findings demonstrated for the first time that people living with HIV from Alborz province, are being exposed to this zoonosis and a relatively high seroprevalence of Toxocara in HIV/AIDS people needs comprehensive health education regarding personal hygiene and how to avoid exposure to this parasite infection, especially in people with an impaired immune system.

Toxocara canis seropositivity in different exposure groups in the Khyber Pakhtunkhwa province of Northwest Pakistan

Human toxocariasis is a highly prevalent zoonosis worldwide but is underreported in most countries. This study was conducted to evaluate Toxocara canis seropositivity in different exposure sub-groups located in the Mardan, Swabi, and Nowshera districts of the Khyber Pakhtunkhwa province of Northwest Pakistan. A total of 400 blood samples were collected from males 15 years of age and older with no animals, with livestock, with dogs and/or cats living in the house, and from butchers and veterinarians or para-veterinarians. Serum was tested using a commercial ELISA kit for detection of IgG antibodies against T. canis. Proportion seropositive was presented for each group and differences between groups were evaluated using the chi-square or Fisher's exact test as appropriate. Possible risk factors obtained through administration of a questionnaire were also evaluated for each sub-population. Overall T. canis seroprevalence was 14.2%, with a significant difference found between the seroprevalence of individuals with no animals (5.0%; 5/100), individuals with dogs and/or cats living in the household (8.0%; 8/100), individuals with livestock (18.0%; 18/100), veterinarians or para-veterinarians (24.0%; 12/50), and butchers (28.0%; 14/50) (p < 0.001). Significant differences in seropositivity by income bracket, education level, and working in the fields were found for some sub-groups. Study findings demonstrate that certain sub-populations, in Northwest Pakistan, may be at greater risk of T. canis infection. Development and implementation of targeted preventive strategies may, therefore, be needed.

Toxocariasis in children with digestive system diseases

Toxocariasis is common among children and causes digestive diseases. The aim of the work was to study the development of toxocariasis in children with digestive diseases. The serum levels of specific IgG to Toxocara canis and Ascaris, levels of IL-4 and TNF-α were determined in 63 children. In addition, tests for parasites and a retrospective survey in order to assess sanitation and hygiene practices were conducted. All children were divided into two groups: group I includes 19 (30.2%) patients seropositive for toxocariasis, and group II – 44 (69.8%) children without any parasites. The level of IL-4 was higher in group I (18.0 ± 6.4 pg/ml) than in group II (7.2 ± 2.0 pg/ml) (P < 0.001. While the level of TNF-α did not differ significantly between groups I (4.5 ± 2.1 pg/ml) and II (3.6 ± 1.1 pg/ml) (P > 0.05). A higher incidence of Toxocara was observed among rural residents (78.9%). Children with toxocariasis more often had soil-pica (42.1%), played with dogs (100%), and did not wash their hands (84.2%) compared to the group of uninfected children. It was noted that hygienic habits and place of living contribute to Toxocara canis infection. IL-4 levels were considerably higher in group I than in group II that can be accounted for the host immune response activation, at the same time, the levels of TNF-α did not differ. Children without toxocariasis had also increased levels of IL-4, which may be related to past helminthic infection. Keywords: children., digestive diseases, interleukin-4, toxocariasis, tumor necrosis factor - α

Human toxocariasis, a silent helminthic disease revealed in Savannakhet, Lao PDR

Toxocariasis is a zoonotic helminthiasis caused by the migrating larvae of Toxocara canis and T. cati, common roundworms of dogs and cats. Our previous study in Savannakhet Province of Lao PDR showed an infection rate of 44.1% of Toxocara spp. in dogs. Thus, we investigate if this previous high prevalence in the definitive hosts influenced the occurrence of human toxocariasis. For that we used a 38 kDa recombinant protein derived from T. canis larvae excretion secretion products in ELISA. Human serum samples were collected in the Lahanam area of Savannakhet province. The population attending the study in Lahanam village were aged from 7 to 59 years old (y/o) 65.9% (54/82) were male and 34.1% (28/82) were female. The total percentage of seropositivity to Toxocara sp. was 30.4% (25/82). Males were more likely to test positive for toxocariasis with a risk ratio of 2.70 (CI95 0.87–4.93). No significant differences between ages were seen. However, it was possible to observe an increase of optical density (OD) values in ELISA according to age. The awareness of the health system on the high prevalence of seropositivity to Toxocara sp. in Savannakhet can prevent irreversible consequences as permanent vision loss and seizures caused by this silent chronic disease revealed in the Lahanam area.

•

The first survey for human toxocariasis was carried out in Savannakhet, Lao-PDR.

•

Seropositivity was higher in males than females.

•

Despite no reported clinical cases of toxocariasis 30.4% of seropositivity was found.

•

People are at risk of exposure to Toxocara sp. larvae in Savannakhet, Lao-PDR.

A new ELISA and western blot technique based on recombinant TES antigen and/or larval antigen for the detection of toxocariasis in humans

Serological antibody detection by enzyme-linked immunosorbent assay (ELISA)- and immunoblot-based methods constitutes the best indicator of human Toxocara infection. Nevertheless, the availability of serological tests, particularly western blots (WB), evaluated for sensitivity and specificity is limited. Therefore, an Anti-Toxocara-ELISA immunoglobulin g (IgG) prototype (Proto-ELISA) and an Anti-Toxocara-Westernblot (IgG) prototype (Proto-WB) were evaluated by testing 541 human sera pre-determined for Toxocara infection by an established in-house Anti-Toxocara-ELISA (IH-ELISA). To evaluate sensitivity and specificity of the newly developed ELISA and WB prototypes, results were compared to IH-ELISA and a commercial WB (Com-WB). Compared to the IH-ELISA, a sensitivity of 93.1% (229/246) and a specificity of 94.6% (279/295) of the Proto-ELISA with a Cohen's κ of 0.88 were obtained. The sensitivity of the Proto-WB was 76.7% (240/313) and specificity was 99.6% (227/228) with a Cohen's κ of 0.73 compared to those of Com-WB. A comparison to the IH-ELISA revealed 91.5% (225/246) sensitivity and 94.6% (279/295) specificity of the Proto-WB with a Cohen's κ of 0.86. Cross-reactivity was observed for some samples positive for Ascaris and Trichinella spp. in the Proto-ELISA, Proto-WB and Com-WB. Overall, the evaluated ELISA and WB prototypes showed high sensitivity and specificity, indicating high reliability of these newly developed tests.

Seroepidemiology, modifiable risk factors and clinical symptoms of Toxocara spp. infection in northern Iran

Toxocariasis is one of the most important and widespread neglected tropical infectious diseases. We designed a cross-sectional study to assess the seroepidemiological aspects of toxocariasis among the general population in northern Iran. A total of 630 rural subjects were enrolled to participate in the study. The presence of anti-Toxocara immunoglobulin G (IgG) was tested using a commercially available enzyme-linked immunosorbent assay. A structured questionnaire was also used to evaluate the potential risk factors and related clinical signs/symptoms. The presence of anti-Toxocara IgG antibodies was detected in 148 of the 630 rural subjects (23.5% [95% confidence interval {CI} 21.8 to 25.1]). By multivariate analysis, age (odds ratio [OR] 2.89 [95% CI 1 to -8.3], p=0.04), eating improperly washed vegetables (OR 4.05 [95% CI 2.47 to 6.64], p<0.001), contact with dogs (OR 3.31 [95% CI 2.13 to 5.12], p<0.001) and exposure to soil (OR 3.56 [95% CI 2.13 to 5.13], p<0.001) were significantly associated with the seroprevalence of Toxocara. The clinical study also demonstrated that the seroprevalence of Toxocara infection was significantly associated with asthma (OR 3.78 [95% CI 1.63 to 8.75], p<0.001) and ophthalmic disorder (OR 1.83 [95% CI 1.04 to 3.21], p=0.034). The findings proved that residents of rural communities in tropical regions may be heavily exposed to Toxocara spp. We highly recommend more investigations in high-risk groups.

Serodiagnostic methods for diagnosing larval toxocariasis

Toxocariasis is a human infection primarily caused by larvae of Toxocara canis from dogs, and also by T. cati from cats. Children have a more significant risk of acquiring the infection due to their closer contact with pets, and greater chances of ingesting soil. Diagnosis of toxocariasis is based on clinical, epidemiological, and serological data. Indirect IgG ELISA is a widely used serodiagnostic method for toxocariasis, with native T. canis TES most commonly used as the antigen. Western blots, using the same antigen, can be used to confirm positive ELISA findings to reduce false-positive results. Improvements in Toxocara serodiagnosis include the use of recombinant TES antigens, simpler and more rapid assay formats, and IgG4 subclass detection. Also, incorporation of recombinant T. cati TES protein increases the diagnostic sensitivity. Development of antigen detection tests using polyclonal and monoclonal antibodies, nanobodies, or aptamers can complement the antibody detection assays, and enhance the effectiveness of the serodiagnosis.

Seroprevalence of human toxocarosis in Europe: A review and meta-analysis

Toxocarosis is distributed worldwide and represents the most prevalent zoonotic helminth infection in industrialized countries, thereby posing a substantial risk for public health. Thus, toxocarosis is one of CDC's Neglected Parasitic Infections that has been targeted for public health action. This systematic review and meta-analysis summarizes Toxocara seroprevalence in general populations from Europe, populations suspected of Toxocara infection and defined risk groups. Random-effects meta-analysis of proportions based on 41 publications resulted in an overall seroprevalence of 6.2% (95% CI: 4.7-8.3%) in the general population of Europe. Subgroup analysis according to decades (1970-2010s) revealed a significant increase in seroprevalence, with the highest value (12.4%; 95% CI: 6.5-22.3%) in the 2010s (χ²=17.87, df=4, P=0.001). There were no significant differences between pooled prevalence rates of European sub-regions (χ²=3.01, df=3, P=0.389). Furthermore, meta-analysis of seroprevalence according to age groups, based on data from 22 publications, indicated a significantly higher pooled seroprevalence of 14.9% (95% CI: 8.5-24.8%) in people more than 50 years of age than in younger age cohorts (χ²=8.33, df=2, P=0.016). Occupational groups exposed to contaminated soil and infected animals bear substantial risk for acquiring Toxocara infection. Due to the close link between animal infection and human Toxocara exposure, a "One Health" approach for the prevention of Toxocara infection in both humans and animals is required.

Seroprevalence of Toxocara spp. antibodies in humans in Africa: A review

BACKGROUND

Human toxocariasis occurs worldwide and is caused by nematodes of the species of the genus Toxocara. Infection occurs by the ingestion of eggs and is usually asymptomatic or oligosymptomatic. However, severe manifestations occur. The burden of disease and its public health impact remain ill-defined. The aim of this review was to summarize all available data on the seroprevalence of toxocariasis on the African continent and factors associated with seropositivity.

METHODS

Twenty-seven original papers published between 1991 and 2017 were identified that provided data suitable for this review. Case-control studies were included and the seroprevalence in the (healthy) control group was used as a surrogate parameter.

RESULTS

Antibodies against Toxocara spp. were found to be frequent in most populations and regions in Africa with the exception of two publications, one from the Democratic Republic of the Congo and one from Djibouti, where all participants were seronegative. The highest proportion of participants with antibodies was found on the island of La Réunion with 359 out 387 study participants being positive (92.8%). Factors associated with seropositivity were reported across studies, including-among others-older age, contact with soil via geophagia, agricultural activity or playing with soil, contact with animals, especially dogs, and low socio-economic status, defined as absence of water supply or poor housing. Three Egyptian studies found male gender to be associated with toxocariasis, whereas in La Réunion females were at increased risk.

CONCLUSIONS

Exposure to toxocariasis seems to be very frequent and common in large parts of the African continent. However, no data are available for most countries. The public health impact of human toxocariasis and the frequency of severe manifestations remain unclear.

Prevalence of Toxocara and Toxascaris infection among human and animals in Iran with meta-analysis approach

BACKGROUND

Toxocariasis is a worldwide zoonotic parasitic disease caused by species of Toxocara and Toxascaris, common in dogs and cats. Herein, a meta-analysis was contrived to assess the prevalence of Toxocara/Toxascaris in carnivore and human hosts in different regions of Iran from April 1969 to June 2019.

METHODS

The available online articles of English (PubMed, Science Direct, Scopus, and Ovid) and Persian (SID, Iran Medex, Magiran, and Iran Doc) databases and also the articles that presented in held parasitology congresses of Iran were involved.

RESULTS

The weighted prevalence of Toxocara/Toxascaris in dogs (Canis familiaris) and cats (Felis catus) was 24.2% (95% CI: 18.0-31.0%) and 32.6% (95% CI: 22.6-43.4%), respectively. Also, pooled prevalence in jackal (Canis aureus) and red fox (Vulpes vulpes) was 23.3% (95% CI: 7.7-43.2%) and 69.4% (95% CI: 60.3-77.8%), correspondingly. Weighted mean prevalence of human cases with overall 28 records was 9.3% (95% CI: 6.3-13.1%). The weighted prevalence of Toxocara canis, Toxocara cati, and Toxascaris leonina was represented as 13.8% (95% CI: 9.8-18.3%), 28.5% (95% CI: 20-37.7%) and 14.3% (95% CI: 8.1-22.0%), respectively.

CONCLUSION

Our meta-analysis results illustrate a considerable prevalence rate of Toxocara/Toxascaris, particularly in cats and dogs of northern parts of Iran. The presence of suitable animal hosts, optimum climate and close contact of humans and animals would have been the reason for higher seroprevalence rates of human cases in our region. Given the significance clinical outcomes of human Toxocara/Toxascaris, necessary measures should be taken.

Low Toxocara Seroprevalence in People in Rural Durango, Mexico

The epidemiology of Toxocara infection in rural Mexico is largely unknown. Therefore, we sought to determine the seroprevalence of Toxocara infection in rural people in a northern Mexican state. We performed a cross-sectional seroprevalence study of 641 people living in rural Durango State including 282 subjects of the general population, 214 subjects of Huichol ethnicity, and 145 subjects of Mennonite ethnicity. Sera of participants were analyzed for the presence of anti-Toxocara immunoglobulin G (IgG) antibodies using a commercially available enzyme immunoassay. Three (0.5%) of the 641 subjects tested were positive for anti-Toxocara IgG antibodies. Of the 3 Toxocara seropositive subjects, two were females, aged 19 and 39 years, and one was male, aged 59 years. They had contacted with dogs, cleaned cat excrement, consumed unwashed raw fruits, contacted soil, or lived in a house with soil floors. Seroprevalence of Toxocara infection was similar among the 3 groups of population studied: 0.4% for the general population, 0.9% for Huicholes, and 0.0% for Mennonites (P = 0.41). In conclusion, the Toxocara seroprevalence found in subjects in rural Durango is low as compared with those reported in people from rural areas in other countries.

Visceral larva migrans detection using PCR-RFLP in BALB/c mice infected with Toxocara canis

Toxocara canis is an important zoonotic roundworm distributed worldwide. The infective larvae of T. canis are one of the causes of visceral larva migrans (VLM), a clinical syndrome in humans. Diagnosing VLM is difficult, and the differential diagnosis of the larval development stage is limited. Therefore, this experimental research aimed to diagnose T. canis larvae using a molecular method, not only in liver tissue, which is the most commonly affected tissue, but also in the limb muscles, lungs and brain tissues. For this purpose, 24 BALB/c mice were infected with 1000 embryonated T. canis eggs. Necropsies were performed on the second, fourth, seventh and 14th days post-infection. While a part of the samples were digested with pepsin-HCl, the molecular method was used for the remainder of the samples to replicate the mitochondrial DNA adenosine triphosphate (ATP) synthase subunit-6 gene region of T. canis. BbsI, a restriction endonuclease, was used to determine the specificity of the amplicons obtained from Polymerase chain reaction (PCR). The detection limit for embryonated eggs was recorded. The PCR results showed that the sensitivity of the PCR analysis was 83.3% in the liver (with 88.8% accuracy), 87.5% in the lungs (with 91.6% accuracy) and 75.0% in the brain, forelimb and hindlimb muscles (with 83.3% accuracy). In all tissues, the test specificity was determined to be 100%. In this study, the molecular method was applied to only experimentally infected BALB/c mice tissues; thus, it is suggested that it can be also employed in different paratenic hosts and materials possibly infected with T. canis.

Preliminary Evidence for the Absence of Cystic Echinococcosis in Gabon: A Cross-Sectional Pilot Survey in Humans and Definitive Hosts

Cystic echinococcosis (CE) is a globally endemic zoonosis caused by the larval stage of the Echinococcus granulosus sensu lato (s.l.) complex. Although the disease is known to be highly prevalent in certain parts of North and East Africa, data on CE, both in humans and definitive hosts, are extremely scarce for Central Africa. The present study assessed the epidemiology of CE in humans and dogs in rural Gabon. An ultrasound and serologic survey was conducted in volunteers from rural villages in Gabon. A two-step approach was used for serological testing with an indirect hemagglutination assay as a screening test and Western Blot as a confirmatory test. Fecal dog samples were analyzed microscopically, and polymerase chain reaction (PCR) amplification of nad1 and cox1 genes was performed when taeniid eggs were visible. Regional hospitals and the national reference center for parasitology in Gabon were contacted for information about previous cases of CE. Randomly selected communities were invited to participate. Three hundred and forty-eight human volunteers from these communities were screened. No suspected cases of CE were detected. Definitive host screening was performed from 128 fecal samples from representative subregions, but no eggs from E. granulosus s.l. were found. No documented cases of echinococcosis were reported from the local health-care institutions and the national diagnostic reference center in Gabon. Cystic echinococcosis seems to be very rare or absent in Gabon. The reason for this lack of evidence for echinococcosis is unknown, but the absence of livestock may play a major role.

Toxocarosis in children: poor hygiene habits and contact with dogs is related to longer treatment

The objective of this study was to investigate the main clinical signs and symptoms of toxocarosis in children and the treatment results. The study group consisted of 66 seropositive children aged 2 to 16 years, evaluated in an outpatient clinic in north-eastern Poland for 24 months. Male gender and living in urban areas predominated in the study population. Children presented with non-specific symptoms, of which the most common was abdominal pain or tenderness, which was reported by 39 (59%) patients. Absolute eosinophil counts were increased in 32 (48%) children. Total IgE concentrations were increased in 31 of 55 (56%) tested children. All evaluated children received albendazole as a first-line treatment. In 19 cases, additional treatment with albendazole and/or diethylcarbamazine was provided. The analysis of possible causes of prolonged treatment revealed that significant risk factors were geophagia [odds ratio (OR), 6.3; 95% confidence interval (95% CI), 1.8–21.8; p < 0.01] and daily contact with a dog [OR, 5.9; 95% CI, 1.3–27.3, p < 0.05]. We hypothesise that poor hygiene habits and daily contact with a dog pose a risk of reinfection and limits treatment efficiency. Because of non-specific signs and frequent lack of eosinophilia, physicians should maintain high levels of suspicion for toxocarosis, particularly in patients who live in regions heavily contaminated with Toxocara eggs.

Toxocariasis in humans in Africa - A systematic review

BACKGROUND

Toxocariasis is a globally distributed zoonosis. The most important definitive hosts are dogs, whereas humans serve as paratenic hosts. Transmission to humans occurs by accidental ingestion of eggs, e.g. by consumption of contaminated fruits or vegetables. Although exposure to Toxocara is usually considered as relatively benign, it is implicated in a range of neurological, ophthalmologic and other organ-specific conditions, some of them with grave consequences. This review provides an overview on the epidemiology, presentation and risk factors of exposure to Toxocara in Africa.

METHODS

A systematic search was performed for studies published after January 1st, 1990, in English, French, Portuguese, Spanish, Dutch or German. The review was prepared according to PRISMA guidelines. Studies on toxocariasis in human populations and contamination in human environments were included.

RESULTS

Sixty-five papers were included. Antibodies against Toxocara spp. in humans were found to be very common across Africa. Severe manifestations have been reported mainly from North Africa. Environmental contamination including soil, vegetables and fruits sold on markets was demonstrated in various locations in Africa.

CONCLUSIONS

Exposure to Toxocara is prevalent across the African continent. However, the complication frequency, the impact of the condition on the individual and the public health relevance of this zoonosis, and the economic impact have never been systematically evaluated.

Prevalence of Toxocara species infection in the U.S.: Results from the National Health and Nutrition Examination Survey, 2011-2014

Toxocariasis is one of the most common neglected infections of poverty in the U.S. with a reported National Health and Nutrition Examination Survey (NHANES) III (1988–1994) seroprevalence of 13.9% based on enzyme immunoassay testing. We reviewed NHANES data from 2011–2014 to assess current levels. Sera collected from NHANES 2011–2014 participants six years and older were tested for exposure using rTc-CTL-1 antigen, a more sensitive and specific recombinant antigen for IgG antibodies for Toxocara spp. These results were subdivided into children (age 6–17) and adults (age ≥ 18) and then compared between various sociodemographic characteristics. Given prior associations of Toxocara exposure with atopic disease and lead exposure, we also reviewed laboratory values including complete blood counts and blood and urine lead levels. Data from 13,509 individuals with Toxocara antibody results were examined including 3337 children (15.2%) and 10172 adults (84.8%). Overall seroprevalence was 5.1%. In adults increased antibody positivity occurred with non-White ethnicity, male gender, less than college-level education and lower income. Among children, increased antibody positivity was solely related to a lack of health insurance. Additionally, seropositivity was associated with increased blood lead and eosinophil levels in adults and both blood and urine lead levels in children. Relative to NHANES III (1988–1994), current data suggest an overall decrease in Toxocara spp. seroprevalence from 13.9% to 5.1%, however this may be artificially lowered due to difference in testing methods used. Persistent disparities appear to be associated with at-risk populations such as minority ethnicity and low socioeconomic status.

Toxocariasis is a pervasive helminth infection transmitted to humans via embryonated eggs from soil contaminated by the feces of dogs and cats (Toxocara canis and T. cati, respectively). The most recent seroprevalence study of Toxocara infection in the United States used the National Health and Nutrition Examination Survey (NHANES) III data collected from 1988 to 1994. At-risk groups identified included male gender, non-White ethnicity and low education and socioeconomic status. Since the original study, dogs and cats have increased in number and an improved testing platform has been created using rTc-CTL-1 antigen to Toxocara spp. with a sensitivity and specificity of 90% and 99%, respectively. In this study, we assessed current seroprevalence based on the NHANES data from 2011 to 2014 using the more specific testing platform. Although overall seroprevalence appears to have decreased from 13.9% to 5.1%; persistent disparities remain associated with at-risk populations including minority ethnicity and low socioeconomic status. Continued work is needed to improve awareness of disease transmission and treatment amongst the general population as well as veterinarians who may care for dogs and cats within the United States and take responsibility for education of the public.