The epidemiology and public health importance of toxocariasis: A zoonosis of global importance

Genetic blueprint of the zoonotic pathogen Toxocara canis

Toxocara canis is a zoonotic parasite of major socioeconomic importance worldwide. In humans, this nematode causes disease (toxocariasis) mainly in the under-privileged communities in developed and developing countries. Although relatively well studied from clinical and epidemiological perspectives, to date, there has been no global investigation of the molecular biology of this parasite. Here we use next-generation sequencing to produce a draft genome and transcriptome of T. canis to support future biological and biotechnological investigations. This genome is 317 Mb in size, has a repeat content of 13.5% and encodes at least 18,596 protein-coding genes. We study transcription in a larval, as well as adult female and male stages, characterize the parasite’s gene-silencing machinery, explore molecules involved in development or host–parasite interactions and predict intervention targets. The draft genome of T. canis should provide a useful resource for future molecular studies of this and other, related parasites.

Toxocara canis is a zoonotic parasite of major worldwide socioeconomic importance. Here, the authors sequence the genome and transcriptome of T. canis, and highlight potential mechanisms involved in development and host–parasite interactions that could support the pursuit of new drug interventions.

Seroprevalence of human Toxocara infections in the Roma and non-Roma populations of Eastern Slovakia: a cross-sectional study

Socioeconomic conditions and health of the Roma population, the most numerous minority in Europe, are worse than that of the non-Roma population. Information about the occurrence of human toxocarosis and other parasitic diseases in the Roma population is scarce or completely missing. The aim of this study was to map the seroprevalence of toxocarosis in the population living in segregated Roma settlements and to compare the data with the occurrence of antibodies in the non-Roma population of Eastern Slovakia. The seropositivity to Toxocara in 429 examined Roma inhabitants of segregated settlements reached 22·1%, while only 4/394 samples of the non-Roma population were found to be positive (odds ratio 27·7, P < 0·0001). Headache, muscle pain, influenza-like symptoms and diarrhoea occurred significantly more often in seropositive persons than in seronegative individuals. In the Roma population positivity was not influenced by gender, level of education and poverty, but age, lack of sanitary facilities and heating with wood significantly increased the risk of infection. It can be assumed that besides the high prevalence of toxocarosis, other parasitic diseases and communicable diseases will also be more prevalent in the Roma population living in segregated settlements.

Seroepidemiology of Toxocara infection in patients with vision impairment and blindness in durango, Mexico

Background

Toxocara infection is a cause of vision impairment and blindness. We aimed to determine the seroprevalence and correlates of Toxocara infection in patients suffering from vision impairment and blindness in Durango City, Mexico.

Methods

Through a cross-sectional seroprevalence study, 204 patients with vision impairment and 19 blind patients were studied for the presence of anti-Toxocara IgG antibodies in Durango City, Mexico. Seroprevalence association with socio-demographic, housing, clinical, and behavioral characteristics of participants was also investigated.

Results

Five (2.5%) of the 204 patients with vision impairment, and none of the 19 patients with blindness were positive for anti-Toxocara IgG antibodies. In total, five of the 223 (2.2%) patients were positive for anti-Toxocara IgG antibodies. Seropositivity to Toxocara was not associated with age, sex, educational level, socio-economic status, presence of underlying diseases or behavioral characteristics of the patients. In contrast, multivariate analysis showed that Toxocara seropositivity was associated with living in a house with soil floor (odds ratio (OR) = 11.14; 95% confidence interval (CI): 1.57 - 78.74; P = 0.01).

Conclusions

This is the first report of Toxocara exposure in patients with vision impairment and blindness in Mexico, and of an association of Toxocara exposure with living in a house with soil floors. Results suggest a low Toxocara exposure in these patients in Durango, Mexico. The risk factor associated with Toxocara exposure identified in this study warrants for further investigation.

Toxocara cati (Nematoda: Ascarididae) in Didelphis albiventris (Marsupialia: Didelphidae) from Brazil: a case of pseudoparasitism

Eggs of Toxocara cati were found in the feces of Didelphis albiventris from a peridomestic urban environment in Brazil. Negative fecal tests following short-term captivity of the opossums, as well as the absence of ascaridids during necropsy, suggest the occurrence of pseudoparasitism. Implications of the findings for the epidemiology of toxocariasis are discussed.

Field evaluation of the efficacy and safety of a combination of spinosad and milbemycin oxime in the treatment and prevention of naturally acquired flea infestations and treatment of intestinal nematode infections in dogs in Europe

Two separate randomised, blinded, multicentre field trials were conducted to evaluate the efficacy and safety of a combination of spinosad and milbemycin oxime (MO) (Trifexis(®), Elanco Animal Health) in the treatment and prevention of naturally acquired flea infestations and intestinal nematode infections in European dogs. Treatments using Trifexis(®) and each control veterinary product (CVP) were administered once on Day 0 in both field studies. In the flea field trial, 11 veterinary clinics in France participated in the study. On Day 0, whole body flea comb counts were conducted on all dogs being evaluated for enrolment. Dogs with ≥7 fleas on Day 0 were enrolled, treated once on Day 0 with spinosad/MO or the CVP (Stronghold(®); selamectin) and then underwent post-treatment flea counts on Days 14 and 30. There were 150 spinosad/MO treated dogs and 71 CVP treated dogs included in the flea effectiveness population. Effectiveness against fleas (% reduction in geometric means; GM) was 98.97% and 97.37% for the spinosad/MO treated dogs, and 97.43% and 93.96% for the CVP dogs on Days 14 and 30, respectively, compared to the pre-treatment baseline flea counts. Of the spinosad/MO dogs, 89.3% and 80.0% had no live fleas on Days 14 and 30, compared to 77.5% and 70.4% of the CVP dogs, respectively. In the nematode field trial, data from 10 veterinary clinics in France and 19 in Ireland were pooled. Faecal samples from dogs at each clinic were analysed. A positive result at screening (parasite eggs from Toxocara canis, Toxascaris leonina, Trichuris vulpis or Ancylostoma caninum) allowed for enrolment. Dogs were randomised to spinosad/MO or the CVP (Milbemax(®); MO/praziquantel). On Day 8, a post-treatment faecal sample was taken and analysed. Of 2333 dogs screened for nematode eggs, 238 dogs were positive with one or more of these nematodes, and 229 were enrolled in the study. Of the 229 dogs, 151 were treated with a single dose of spinosad/MO, and 77 were treated with a single dose of CVP. Post-treatment effectiveness against all nematodes (% reduction GM) was achieved with reductions of 98.57% and 97.57% for the spinosad/MO treated dogs and CVP dogs, respectively, as compared to the pre-treatment baseline faecal egg counts. Trifexis(®) was shown to be safe and effective against natural infestations of fleas as well as mixed and single intestinal nematode infections in client owned dogs in Europe when administered as a single oral administration at the recommended dose.

Canine fecal contamination in a metropolitan area (Milan, north-western Italy): prevalence of intestinal parasites and evaluation of health risks

Intestinal parasites of dogs represent a serious threat to human health due to their zoonotic potential. Thus, metropolitan areas presenting high concentrations of pets and urban fecal contamination on public areas are at sanitary risk. Major aim of this survey was to determine prevalence of zoonotic parasites in dog fecal samples collected from public soil of Milan (north-western Italy). Differences in parasites prevalence distribution were explored by a geographical information system- (GIS-) based approach, and risk factors (human density, sizes of green parks, and dog areas) were considered. The metropolitan area was divided into 157 rectangular subareas and sampling was performed following a 1-kilometer straight transect. A total of 463 fecal samples were analyzed using centrifugation-flotation technique and ELISA to detect Giardia and Cryptosporidium coproantigens. A widespread fecal contamination of soil was highlighted, being fecal samples found in 86.8% of the subareas considered. The overall prevalence of intestinal parasites was 16.63%. Zoonotic parasites were found, such as Trichuris vulpis (3.67%), Toxocara canis (1.72%), Strongyloides stercoralis (0.86%), Ancylostomatidae (0.43%), and Dipylidium caninum (0.43%). Giardia duodenalis was the most prevalent zoonotic protozoa (11.06%), followed by Cryptosporidium (1.10%). Faeces from subareas characterized by broad green areas showed to be particularly prone to infection.

Toxocara seroprevalence among clinically healthy individuals, pregnant women and psychiatric patients and associated risk factors in Shandong Province, Eastern China

BACKGROUND

Toxocarosis is a widespread zoonosis caused by the ascarid nematodes Toxocara canis and Toxocara cati, which primarily infect dogs and cats, respectively. Most human infections with Toxocara are asymptomatic; however, some infected individuals may develop a serious illness and even death. Nevertheless, epidemiological knowledge regarding the prevalence and risks associated with Toxocara infection is limited in China. Therefore, we performed a cross-sectional pilot study and estimated the seroprevalence of Toxocara infection in humans in Shandong Province, eastern China for the first time, from June 2011 to July 2013, involving clinically healthy individuals, pregnant women and psychiatric patients, aiming to attract public attention to Toxocara infection.

METHODOLOGY/PRINCIPLE FINDINGS

Seroprevalence of Toxocara was determined using an enzyme-linked immunosorbent assay based on a cross-sectional study conducted in Qingdao and Weihai, Shandong Province, eastern China. Factors potentially associated with Toxocara infection were identified by logistic regression analysis. The overall Toxocara seroprevalence among the study population (n = 2866) was 12.25%, and a significantly higher seroprevalence in psychiatric patients (16.40%, 73/445) than that in clinically healthy individuals (13.07%, 187/1431) and pregnant women (9.19%, 91/990) was revealed. Univariate analyses suggested that keeping dogs at home (OR = 0.06, 95% CI 0.05-0.08, P<0.001), contact with cats and dogs (OR = 0.42, 95% CI 0.33-0.53, P<0.001) and exposure with soil (OR = 0.37, 95% CI 0.28-0.49, P<0.001) were risk factors associated with Toxocara infection.

CONCLUSIONS/SIGNIFICANCE

The present study revealed, for the first time, that human infection with Toxocara is common in eastern China, posing a significant public health concern. Increasing human and dog populations, population movements and climate change all will serve to increase the importance of this zoonosis. Further studies under controlled conditions are necessary to define potential morbidity associated with Toxocara infection.

Seroepidemiology of Toxocara canis infection among primary schoolchildren in the capital area of the Republic of the Marshall Islands

BACKGROUND

Toxocariasis, which is predominantly caused by Toxocara canis (T. canis) infection, is a common zoonotic parasitosis worldwide; however, the status of toxocariasis endemicity in the Republic of the Marshall Islands (RMI) remains unknown.

METHODS

A seroepidemiological investigation was conducted among 166 primary school children (PSC) aged 7-12 years from the capital area of the RMI. Western blots based the excretory-secretory antigens of larval T. canis (TcES) was employed, and children were considered seropositive if their serum reacted with TcES when diluted at a titer of 1:64. Information regarding demographic characteristics of and environmental risk factors affecting these children was collected using a structured questionnaire. A logistic regression model was applied to conduct a multivariate analysis.

RESULTS

The overall seropositive rate of T. canis infection was 86.75% (144/166). In the univariate analysis, PSC who exhibited a history of feeding dogs at home (OR = 5.52, 95% CI = 1.15-26.61, p = 0.02) and whose parents were employed as nonskilled workers (OR = 2.86, 95% CI = 1.08-7.60, p = 0.03) demonstrated a statistically elevated risk of contracting T. canis infections. Cleaning dog huts with gloves might prevent infection, but yielded nonsignificant effects. The multivariate analysis indicated that parental occupation was the critical risk factor in this study because its effect remained significant after adjusting for other variables; by contrast, the effect of dog feeding became nonsignificant because of other potential confounding factors. No associations were observed among gender, age, consuming raw meat or vegetables, drinking unboiled water, cleaning dog huts with gloves, or touching soil.

CONCLUSIONS

This is the first serological investigation of T. canis infection among PSC in the RMI. The high seroprevalence indicates the commonness of T. canis transmission and possible human risk. The fundamental information that the present study provides regarding T. canis epidemiology can facilitate developing strategies for disease prevention and control.

Intestinal parasites of owned dogs and cats from metropolitan and micropolitan areas: prevalence, zoonotic risks, and pet owner awareness in northern Italy

Intestinal parasites of dogs and cats are cosmopolitan pathogens with zoonotic potential for humans. Our investigation considered their diffusion in dogs and cats from northern Italy areas, specifically the metropolitan area of Milan and two micropolitan areas of neighboring provinces. It included the study of the level of awareness in pet owners of the zoonotic potential from these parasites. A total of 409 fresh fecal samples were collected from household dogs and cats for copromicroscopic analysis and detection of Giardia duodenalis coproantigens. The assemblages of Giardia were also identified. A questionnaire about intestinal parasites biology and zoonotic potential was submitted to 185 pet owners. The overall prevalence of intestinal parasites resulted higher in cats (47.37%−60.42%) and dogs (57.41%−43.02%) from micropolitan areas than that from the metropolis of Milan (dogs: P = 28.16%; cats: P = 32.58 %). The zoonotic parasites infecting pets under investigation were T. canis and T. cati, T. vulpis, Ancylostomatidae, and G. duodenalis assemblage A. Only 49.19% of pet owners showed to be aware of the risks for human health from canine and feline intestinal parasites. Parasitological results in pets and awareness determination in their owners clearly highlight how the role of veterinarians is important in indicating correct and widespread behaviors to reduce risks of infection for pets and humans in urban areas.