Quantifying sources of environmental contamination with Toxocara spp. eggs

A rich body of work has reported levels of infection with Toxocara species in definitive hosts, and the frequency of eggs in the environment, in many different regions and situations. These have greatly increased our understanding of the relationship between egg excretion from companion and wild animals and the risk of human infection by inadvertent ingestion of eggs from soil and other environmental reservoirs. Nevertheless, it is difficult to compare studies directly because of vagaries in sampling and laboratory methods, a preponderance of prevalence rather than abundance data, and a lack of studies that systematically sample different sympatric definitive host populations. Such comparisons could be instructive, for example to determine the relative contributions of different definitive host populations and categories to environmental contamination in specified areas, and hence guide priorities for control. In this article we use estimates of host density and infection levels in the city of Bristol, UK, as a case study to evaluate the relative contribution of sympatric cats, dogs and foxes to overall environmental contamination with eggs. Results suggest that dogs, especially those less than 12 weeks of age, dominate total egg output, but that this is modified by degree of access to public areas and removal of faeces, such that foxes could take over as the primary source of eggs. Results and conclusions are likely to differ among specific locations. The general aim is to show how an improved quantitative framework for epidemiological studies of Toxocara spp. egg contamination can help to advance understanding and the effectiveness of control strategies in future.     

Seroprevalence,risk factors,and clinical symptoms of Toxocara spp. infection among children 3-15 years old in northern Iran

The World Health Organization has categorized toxocarosis as a neglected tropical disease despite its significant impact on high-risk groups such as children. This study aimed to investigate the seroprevalence, risk factors, and clinical symptoms of Toxocara spp. infection among children 3–15 years old in northern Iran. A total of 386 children were enrolled in the study. All serum samples were tested for the presence of IgG antibodies against Toxocara spp. infection using an enzyme-linked immunosorbent assay. Moreover, relevant risk factors and clinical symptom data were obtained using questionnaires. Data analysis was performed using the SPSS software version 24. The overall seroprevalence of Toxocara spp. infection was found 2.85 % (11/386). However, Toxocara spp. infection was high for some risk factors, including eating soil (14.3 %), contacting cats (6.7 %), and consuming raw vegetables (3.7 %). However, there were no statistically significant differences regarding the risk factors and socio-demographic characteristics. Considering the clinical symptoms, Toxocara spp. infection was different in children with eosinophilia (20 %), ocular disorders (8.3 %), skin disorders (7.7 %), liver disorders (4.5 %), and stomach ache (4.2 %), although not statistically significant. The results revealed that the seroprevalence of Toxocara spp. infection was relatively low in children in northern Iran. It is suggested to conduct more studies in different parts of Iran to gain a deeper understanding of the toxocarosis seroprevalence and its status in high-risk groups such as children with asthma, hypereosinophilic syndrome, allergic skin disorders, and epilepsy.     

Studies on flotation techniques for the recovery of helminth eggs from soil and the prevalence of eggs of Toxocara spp in some Kansas public places

A technique for extracting Toxocara spp eggs from soil had a recovery efficiency ranging from 53% to 68%. Using the technique, 50 of 232 (22%) soil samples from city and university properties were found to be contaminated with eggs of Toxocara spp. Of 50 samples from highway rest areas, 8 (16%) were contaminated. From a public health standpoint, it was particularly noteworthy that 9 of 23 (39%) samples from sandboxes in student family quarters were contaminated with Toxocara spp eggs.     

Environmental contamination by eggs of Toxocara species

A study was conducted to determine the level of contamination with Toxocara spp. eggs in parks and playgrounds in several central Illinois communities. A total of 135 composite 50-g soil samples were collected from 23 parks and public places in three cities in central Illinois. Of these soil samples, 22 (16.3%) contained from one to thirteen Toxocara spp. eggs. A total of 40 fecal samples were collected from the same parks. Toxocara spp. eggs were found in two (5%) of the samples.     

Examination of Australian backyard poultry for Salmonella,Campylobacter and Shigella spp., and related risk factors

Worldwide, foodborne illness is a significant public health issue in both developed and developing countries. Salmonellosis, campylobacteriosis and shigellosis are common foodborne gastrointestinal illnesses caused by the bacteria Salmonella spp., Campylobacter spp. and Shigella spp. respectively. These zoonotic diseases are frequently linked to eggs and poultry products. The aim of this study was to investigate the presence of these pathogens in Australian backyard poultry flocks and to determine risk factors for these pathogens. Poultry faeces samples were collected from 82 backyards and screened for Salmonella spp., Campylobacter spp. and Shigella spp. using qPCR. A questionnaire was administered to the backyard poultry owners to assess their knowledge regarding management of poultry and eggs and to identify potential risk factors that may contribute to the presence of zoonotic pathogens in the flocks. One composite faecal sample was collected from each backyard (82 samples). Composite sampling here means taking one or more grab samples from a backyard to make up approximately 10 grams. Four per cent of samples, that is 4% backyards tested, were positive for Salmonella spp., 10% were positive for Campylobacter spp. and none were positive for Shigella spp. A higher infection rate was seen in multi-aged flocks (24%) compared with the single-aged flocks (3%). The survey found that many participants were engaging in risky food safety behaviours with 46% of participants responding that they washed their eggs with running water or still water instead of wiping the dirt off with a damp cloth to clean the eggs and 19% stored their eggs at room temperature. This study demonstrated that backyard poultry may pose a potential risk for salmonellosis and campylobacteriosis. Additionally, Australian public health and food safety regulations should be modified and effectively implemented to address the risks associated with backyard poultry husbandry.     

Detection and identification of Toxocara canis DNA in bronchoalveolar lavage of infected mice using a novel real-time PCR

Toxocarosis is a zoonosis with worldwide distribution caused by Toxocara spp. of dogs and cats. In humans, diagnosis relies mainly on detection of parasite-specific antibodies. Although serological assays in current use have defined sensitivity and specificity, the problem of cross-reactivity still remains, particularly in areas of endemic polyparasitism. Microscopic detection of the parasite in tissue biopsies is not recommended for diagnosis because larvae can be difficult to locate, and finding the parasite eggs in faeces is not applicable since the larvae do not develop to the adult stage in the human host. In this study we describe a novel real-time PCR (‘Nemo-PCR’) that, in combination with DNA sequencing, allows the detection and identification of Toxocara canis and other nematodes in the Superfamily Ascaridoidea. Results indicate that this approach can detect Toxocara spp. DNA in bronchoalveolar lavage (BAL) of experimentally-infected mice. For diagnostic purposes further studies are necessary to evaluate this assay including testing human BAL fluid. The availability of such a direct assay would improve diagnosis of toxocarosis particularly for patients with pulmonary signs and symptoms.     

Recovery threshold of Toxocara canis eggs from soil

The purpose of this study was to evaluate the threshold of Toxocara canis eggs form soil samples through utilisation of a centrifuge-flotation technique (CFT). Aliquots of soil (1 g each) were artificially contaminated with known numbers of T. canis eggs (1, 10, 25, 50, 100, and 200 eggs). The threshold was evaluated based on a CFT using zinc sulphate (Zn₂SO₄) and sodium nitrate (Na₂NO₃) solutions at a specific gravity of 1.20. The number of eggs recovered was directly proportional to the number of eggs employed to seed the soil. Both solutions enabled full recovery of samples containing merely three eggs; only Zn₂SO₄ demonstrated efficiency in soil contaminated with a single egg. A recovery rate of 100% was obtained for all tests with samples containing 10 and 25 eggs for Zn₂SO₄ and Na₂NO₃, respectively_. There was no difference in the mean number of recovered eggs regarding either the efficacy of the solutions or the repetition of evaluations in the same trial (p > 0.05). Therefore, the CFT is efficient for the detection of Toxocara eggs, even in samples containing low egg numbers.     

Contamination of soil with Toxocara eggs in urban (Prague) and rural areas in the Czech Republic

Contamination of soil with feline and canine ascarid eggs in public parks, backyards and sand pits in Prague, Czech Republic was investigated in this work. Soil samples from shelters and rural areas were also collected. The comparison of soil from different areas (urban, rural, backyards and shelters) exhibited significant difference (chi(2)=32.16, d.f.=3 and p<0.0001). The highest rate of contamination (45%) was found in backyards inhabited by feral cats. The eggs of Toxocara spp. were found in 20.4% of parks, 10% of shelters and 5% of rural samples. Mean egg density per sample from Prague parks was 6.2 eggs/100g of soil. In 126 composite samples from children's and pits, the prevalence of Toxocara eggs was 11.90%. The number of eggs in positive samples varied from 2 to 22 (per 100g). A high proportion (46.9%) of eggs was fully embryonated. There was no difference between the sand pits with or without formal exclusion of dogs (chi(2)=0.6, d.f.=1 and p<0.0001).     

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.     

Prevalence of Toxocara spp. eggs in the soil of public parks in Ankara, Turkey

One hundred and seventy soil samples from forty-six public parks in Ankara area were examined to determine the level of contamination with Toxocara spp. eggs. 30.6% of the 170 soil samples were contaminated with Toxocara spp. eggs. The number of eggs in the positive soil samples varied from 1 to 10. A high proportion of the eggs was fully embryonated. The findings demonstrate the common occurrence of these eggs in locations likely to be important in the transmission of visceral larva migrans. Of 19 fecal collected, 5 (26.3%) contained Toxocara spp. eggs. Eggs of Ancylostomidae, Toxascaris leonina, Trichuris spp., Taenia spp. and Enterobius vermicularis were also recovered from 17.6, 4.1, 2.4, 1.8 and 1.2% of soil samples, respectively.     

Investigation of soil contaminated with Toxoplasma gondii oocyst in urban public environment,in Brazil

In this study, we determined the occurrence of Toxoplasma gondii oocysts in soil samples from public places. A total of 120 samples were collected from 24 sites, including squares, parks, university, hospitals in the city of Recife. The recovered oocysts were subjected to a nested-PCR test, and nine sites (9/24) were found to be positive for gene of apicomplexan parasites. The PCR product was sequenced, and 8.33% (10/120) of the samples showed 100% similarity to T. gondii DNA. T. gondii oocysts were detected in 75% (3/4) of the evaluated hospital soil samples and in 23.81% (5/21) soils samples from the public squares and parks. The results of this study demonstrate the potential of the soil in the areas analyzed as a source of T. gondii infection and therefore highlight the importance of devising educational strategies on the use of these sites, in addition to future cleaning protocols in public areas.     

A survey on Toxocara cati eggs on the hair of stray cats: A potential risk factor for human toxocariasis in Northeastern Iran

The objective of this study was to investigate the presence of Toxocara eggs on the hair of stray cats. The total number of stray cats trapped and included in the trial was 167 that were collected weekly from different residential areas of Mashhad, in northeastern Iran, from November 2016 to December 2017. Among the 167 cats, 18 (10.8%) of them were positive to T. cati eggs in their hair. In the positive cats, 7 (39%) were adult, 1 (6%) was juvenile and 10 (55%) were kittens. Overall, the mean number of eggs from positive cats was 3.9 ± 1.7 eggs per gram (epg) of hair per cat with an average of 3.1 ± 1.4 in adults, 4.9 in juveniles and 4.3 ± 1.6 in kittens. In total, 39.9% of the eggs recovered were non-viable 35.5% were viable, 22.2% were embryonating and 2.3% were embryonated which embryonated eggs were found only in juveniles. Based on our data, kittens were responsible for 61.7% of the total number of eggs. The age of the cat was found to be an important risk factor associated with parasitic infection.. This study showed that cat hair contaminated by T. cati eggs in different developmental stages represents of potential source for human toxocariasis.     

Evaluation of the effect of Toxocara cati infection in the mouse model of allergic asthma: Exacerbation of allergic asthma symptoms and Th2 types of response

Toxocariasis is considered a neglected disease despite the importance of Toxocara spp. infections for human health and is little recognized as a significant problem by public health institutions in developing countries. Epidemiological studies suggest that infection with Toxocara cati contributes to the development of allergic asthma.In the present study, we investigated the effect of T. cati infection on experimental allergic airway inflammation using murine model. BALB/c mice were infected by oral administration with 500 embryonated T. cati eggs followed by ovalbumin (OVA) sensitization and challenge to induce allergic airway inflammation. Infection with T. cati in combination with OVA treatment leads to exacerbation of pulmonary inflammation, eosinophilia, airway hyperresponsiveness, OVA specific IgE. Cytokines measurement in bronchoalveolar lavage indicated that the levels of IL-4 and IL-5 in BAL fluid significantly increased after T. cati infected, OVA treated or a combination of both. Increased level of IL-5 was measured in the lungs of T. cati-infected or OVA-treated mice compared with controls. Moreover, combining infection and OVA treatment significantly increase the level of these cytokines.A direct association between T. cati infection and asthma was found in murine model. Although a wide range of helminth species have been demonstrated to modulate allergic responses, most notably the intestinal nematode T. cati, increases airway hyperresponsiveness, lung histopathology, eosinophil recruitment, and Th2 cytokines in alum-sensitized models of airway allergy.     

An investigation of Leishmania spp. in Didelphis spp. from urban and peri-urban areas in Bauru (São Paulo, Brazil)

Blood and bone marrow samples were taken from 112 Didelphis spp., collected between March 2005 and February 2006, from urban and peri-urban areas of Bauru, São Paulo State, Brazil, to evaluate the hypothesis that these animals might constitute a reservoir of Leishmania spp. Anti-Leishmania ssp. antibodies were screened in the serum samples using an enzyme-linked immuno-sorbent assay (ELISA) and the polymerase chain reaction (PCR). PCR was performed on fragments of DNA samples from Leishmania spp. using primers 13A and 13B, and showed a positive outcome in 91.6% of the 112 samples tested. Of the 107 samples analyzed by ELISA, 71% were positive. Evidence of epidemiological risk factors such as a circulating parasite and freely moving vectors suggests that Didelphis spp. may participate in the transmission cycle of Leishmania spp. in Bauru.     

Observations on the occurence and specificity of anti-bodies produced by infected hosts against the acetyl-cholinesterase present in some common gastrointestinal nematode parasites

Sera from hosts infected with a variety of nematodes were examined for the presence of antibodies against nematode acetylcholinesterase (AChE). Antibodies were detected in the serum from hosts infected with Oesophagostomum spp., Ostertagia spp. and Trichostrongylus spp., but not in serum from hosts infected with Cooperia pectinata or Haemonchus spp., Toxocara spp. or Trichuris vulpis. In those infections in which anti-AChE antibodies were found, some individual animals failed to produce detectable antibodies. The enzyme appeared to possess antigenic specificity at the genus but not the species level.     

Dogs and pigs are transport hosts of Necator americanus: Molecular evidence for a zoonotic mechanism of human hookworm transmission in Ghana

Hookworm infection (Necator americanus and Ancylostoma spp) causes significant morbidity in resource‐limited countries. Dog and pig ownership is associated with human infection, although the mechanism through which animals increase risk remains unknown. We first confirmed this association in Kintampo North, Ghana, using a retrospective analysis and serology, followed by a prospective molecular study of animal faeces. As a proxy of exposure to dog faeces, we analysed immunoreactivity of human serum to the zoonotic nematode Toxocara canis. Anti‐Toxocara antibodies were present in 62% of samples (n = 89), and reactivity was associated with dog ownership. A subsequent prospective study revealed that 43% of dog and 56% of pig faecal samples contained hookworm eggs by microscopy. PCR analysis confirmed the presence of N. americanus DNA in 47% of samples from dogs and 56% pig samples. Nematode larvae were successfully cultured from samples collected from 36 dogs and seven pigs. These results demonstrate that dogs and pigs have a likely role in the transmission of N. americanus in endemic communities.     

Parasitology and urban livestock farming in nigeria: prevalence of ova in faecal and soil samples and animal ectoparasites in Makurdi

Domestic environmental pollution resulting from urban livestock farming was investigated in Makurdi using parasitological techniques. The test tube flotation technique was used for the parasitological analysis of animal faecal matter and soil samples collected from residential premises. Ectoparasitic fauna of dogs, goats, sheep and cattle cohabiting with humans within the same residential compound were also collected and identified. The hand-picking and body brushing methods were employed to search for ticks, fleas, lice and mites. Of the 150 soil samples examined, 55 (36.7 %) were positive for 1 or more eggs of helminth parasites. There was no significant difference in the distribution of eggs in the soil samples from the 3 areas sampled (Chi2 = 0.046, df = 2, P > 0.05). Ascaris species were the dominant parasite eggs found. Of the 180 faecal samples examined, 107 (59.4 %) were positive for 1 or more eggs of helminth parasites. Chi-square analysis showed no significant difference in the level of infection of different animal faeces sampled (Chi2 = 5.74, df = 4, P > 0.05). Ascaris species were again the dominating helminth parasite eggs found. There was also no significant difference in the prevalence of helminth eggs in the animal faecal samples from the 3 areas sampled (Chi2 = 5.99, df = 4, P > 0.05). A total of 1908 ectoparasites was recovered (ticks: 32.80 %; lice: 22.43 %; fleas: 22.06 % and mite: 22.69 %). There was no significant difference in infestation animals between sexes (Chi2 = 0.10, df = 4, P > 0.05). The predominant genus encountered for ticks were Amblyomma, while Linognathus (43.90 %), Ctenocephalides (97.38 %) and Sarcoptes (58.89 %) were most predominant for lice, fleas and mites respectively. The public health implications of the findings, especially as these relate to the increasing incidence and prevalence of zoonotic infections, are discussed.     

Enteric parasites of free-roaming,owned, and rural cats in prairie regions of Canada

The objective of this study was to determine prevalence, intensity, and zoonotic potential of gastrointestinal parasites in free-roaming and pet cats in urban areas of Saskatchewan (SK) and a rural region in southwestern Alberta (AB). Fecal samples were analyzed using a modified double centrifugation sucrose flotation to detect helminth eggs and coccidian oocysts, and an immunofluorescence assay to detect Giardia and Cryptosporidium. Endoparasite prevalence was higher in samples from rural AB cats (41% of 27) and free-roaming SK cats (32% of 161) than client-owned SK cats (6% of 31). Parasites identified using morphological and molecular techniques included Toxocara cati, Toxascaris leonina, Baylisascaris-type eggs, Eucoleus aerophilus, Taenia taeniaeformis, Isospora spp., Cryptosporidium spp., and zoonotic genotype A of Giardia duodenalis. This study demonstrates significant differences in endoparasite prevalence in feline populations, and the value of molecular techniques in fecal-based surveys to identify and determine parasite zoonotic potential.     

Helminth parasites of dogs from two resource-limited communities in South Africa

Biological samples were collected from dogs in resource-limited communities in the North-West and Gauteng Provinces of South Africa to assess the prevalence of helminth parasitism. These samples included adhesive tape peri-anal skin swabs and fresh faecal samples for helminth examination, and thick and thin blood films (smears) and whole-blood samples in anticoagulant for examination of filarial nematode microfilariae and haemoprotozoa. The eggs of Ancylostoma caninum, Toxocara canis, Toxascaris leonina, Dipylidium caninum and taeniids were identified. None of the blood samples and smears tested positive for microfilariae of Dirofilaria immitis or Dipetalonema spp. or for haemoprotozoa. The adhesive tape swabs were negative for cestode eggs and segments. Most of the helminth parasites identified in this study are zoonotic and consequently are regarded as a public health hazard.     

Prevalence,quantitative load and genetic diversity of Campylobacter spp. in dairy cattle herds in Lithuania

Background

Campylobacteriosis is a zoonotic disease, and animals such as poultry, pigs and cattle may act as reservoirs for Campylobacter spp. Cattle shed Campylobacter spp. into the environment and they can act as a reservoir for human infection directly via contact with cattle or their faeces or indirectly by consumption of contaminated food. The aim of this study was to determine the prevalence, the quantitative load and the genetic strain diversity of Campylobacter spp. in dairy cattle of different age groups.

Results

Faecal samples of 200 dairy cattle from three farms in the central part of Lithuania were collected and examined for Campylobacter. Cattle herds of all three farms were Campylobacter spp. positive, with a prevalence ranging from 75% (farm I), 77.5% (farm II) to 83.3% (farm III). Overall, the highest prevalence was detected in calves (86.5%) and heifers (86.2%). In contrast, the lowest Campylobacter prevalence was detectable in dairy cows (60.6%). C. jejuni, C. coli, C. lari and C. fetus subsp. fetus were identified in faecal samples of dairy cattle. C. upsaliensis was not detectable in any sample. The high counts of Campylobacter spp. were observed in faecal material of dairy cattle (average 4.5 log₁₀ cfu/g). The highest numbers of Campylobacter spp. were found in faecal samples from calves (average 5.3 log₁₀ cfu/g), whereas, faecal samples from cows harboured the lowest number of Campylobacter spp. (average 3.7 log₁₀ cfu/g). Genotyping by flaA PCR-RFLP analysis of selected C. jejuni isolates showed that some genotypes were present in all farms and all age groups. However, farm or age specific genotypes were also identified.

Conclusions

Future studies are needed to investigate risk factors related to the degree of colonisation in cattle. Based on that, possible measures to reduce the colonisation and subsequent shedding of Campylobacter in cattle could be established. It is important to further investigate the epidemiology of Campylobacter in the cattle population in order to assess associated risks to public health.