Human toxocariasis and direct contact with dogs

Toxocariasis in man is traditionally thought to be contracted through the ingestion of eggs from contaminated soil. The disease may manifest itself in different syndromes such as ocular larval migrans, visceral larval migrans and covert toxocariasis. This paper assesses the evidence for the soil contamination hypothesis and proposes that direct contact with dogs may provide a better explanation of the epidemiology of the disease. Hair was collected from 60 dogs from various places in Ireland and the UK and examined for the presence of Toxocara canis eggs. T. canis eggs were found in the hair of 25 per cent of the dogs; in total, 71 eggs were recovered, of which 4.2 per cent were embryonated and 23.9 per cent were embryonating. The maximum densities of the embryonating and embryonated eggs were 180 and 20 eggs per gram of hair, respectively, much higher than the densities reported for soil samples. It is suggested that dogs infected with T. canis may infect people by direct contact.     

The investigation of Toxocara canis eggs in coats of different dog breeds as a potential transmission route in human toxocariasis

This study was undertaken to determine the prevalence of Toxocara canis eggs on the coats of dogs (a potential etiological factor for human toxocariasis) and to see if there were mainly a dog breed and coat type effects for the presence of eggs on the coat. Hair samples were collected from the different breeds of 51 domestic pet dogs and examined for the presence of T. canis eggs. A total of 62 T. canis eggs (all viable) were found in 21.56% of the dogs. Forty-nine (79.03%) of the eggs recovered were unembryonated, 8 (12.90%) were embryonating, and 5 (8.06%) were embryonated. The maximum densities of the embryonating and embryonated eggs were 93 and 8.45 eggs per gram (epg) of hair, respectively. The number of eggs recovered was much higher than those previously reported for soil samples. Although the statistical analysis for all dogs in this study showed that there were no breed (P>0.4), coat type (P>0.8), sex (P>0.1), age group (P>0.1) and hair length (P>0.3) effects for the presence of T. canis eggs per gram of hair, the majority of dogs (82%) with T. canis eggs in their coats were breeds that had double coats with thick undercoats suggesting that the coat characteristic may play a role for providing a suitable environment for the development of T. canis eggs. Also 82% of infected dogs were under 1 year of age indicating that the age of dog is a very important risk factor. The present study indicates that direct contact with T. canis infected dogs may be a potential etiological factor for human toxocariasis.     

Transfer of infection-induced immune protection to Toxocara canis in a mouse model

Groups of mice were vaccinated twice with soluble extracts of embryonated eggs, females or males of Toxocara canis, or horse serum, and infected with 2,000 homologous embryonated eggs. Recovery of larvae on the fifth day by digestion of mesenteric lymph nodes, liver, lung, brain, and carcass revealed a slight but nonsignificant protection elicited by the parasite materials. Other groups were immunized by homologous infections. A single, 200-day-old infection increased importantly the number of larvae resulting from a challenge, possibly by inducing an immunosuppression in the host. Two infections given within 11 months protected partially against the larvae of a challenge, particularly by trapping the parasites in the liver. Transfer of mesenteric lymph node cells from twice infected mice reduced the total number of parasites, and the liver and lung parasitism of a challenge in the recipients, whereas transfer of serum decreased the total number of parasites and the brain and carcass parasitism. The combination of cells and serum acted synergistically in lungs and brain but antagonistically in liver and carcass.     

Patent Toxocara canis infections in previously exposed and in helminth-free dogs after infection with low numbers of embryonated eggs

The outcome of Toxocara canis infections in the canine host depends on the migratory pathway of parasite larvae (somatic or tracheal) which is considered to be related to the host's age and its immune status. However, field studies attest high prevalences of patent T. canis infections in adult animals. The controlled induction of patent infections with low doses of embryonated eggs was investigated in 18 beagles in a 7-month study until their 16th life month. The animals were assigned to three groups, each consisting of three vertically infected dogs (with a short patent infection as pups before anthelmintic treatment) and three helminth-free dogs. At study days 10 and 40, the animals of groups 1 and 3 were given each 100 embryonated T. canis eggs. In each case, group 1 was treated 10 days post-infection with Milbemax, while dogs of group 3 remained untreated. Control group 2 was not experimentally infected but treated as group 1. Two weeks after first egg administration, a sharp increase of specific antibody reactions in ELISA and increased eosinophilic counts indicated larval invasion in all infected dogs. 42-56 days following first infection, patent infections were detected coproscopically in all animals of group 3, but in none of the uninfected dogs (group 2) or the infected and treated dogs (group 1). Following a 3-month observation period, all animals of the three groups were treated with piperazine citrate to eliminate intestinal infections and all were administered 100 embryonated eggs. Subsequently, patent infections developed in animals of all groups: in one of the infected and treated animals of group 1, in five of the so far not infected control group 2 and in four of the dogs with previous patent infections (group 3). Susceptibility to patent infections was not significantly altered in T. canis-free dogs compared to dogs with previous patent infection (vertically acquired or experimentally induced). However, dogs of group 1 treated with Milbemax after repeated egg administration developed a significantly increased resistance to patent infections as compared to control dogs (group 2). Observed prepatency periods were between 40 and 56 days and did not differ in the three groups. Even in urban areas, facing high infection pressure with Toxocara eggs maintained by a high dog and fox population, dogs of all ages are at risk to develop patent T. canis infections.     

Acquired immunity to Toxocara canis infection in mice

Acquired immunity develops against Toxocara canis infection in mice, and NIH mice are more immunoresponsive than CD1 mice. Twice infected NIH female mice showed 27% reduction in the total larval recoveries compared with non-sensitized controls. Twice-infected NIH male, and CD1 (both sexes) mice showed a negligible reduction in the total recoveries, though a significant (P less than 0.05) number of larvae were retained in the liver compared with the non-sensitized controls. All twice-infected mice showed a significant reduction in the number of larvae recovered from the brain compared with once-infected mice. Vaccination using ultraviolet irradiated embryonated eggs gave the best protection against reinfection. Excretory/secretory antigen afforded less protection, whilst whole adult worm vaccine and whole L2 culture vaccine gave no protection. Vaccinated mice had a higher 'free:penetrating ratio' of larvae in their intestine than similarly challenged but non-vaccinated mice. When the ileum was examined histologically 9 h post-infection, an inflammatory reaction was seen around the penetrating larvae in the sensitized and vaccinated mice but not in untreated controls, suggesting a role played by the intestine in the resistance against T. canis infection in mice.     

Infectivity and pathogenicity of 14-month-cultured embryonated eggs of Toxocara canis in mice

Infectivity and pathogenicity to mice of embryonated eggs of Toxocara canis, that had been maintained in 2% formalin for 14 months at 4 degrees C, were evaluated by immunological and pathological assessment at 1, 4, 8, 12, 16, 20, 24, 28, 42 and 67 weeks post-infection (WPI). On each date, three infected mice and two age-matched uninfected mice were sacrificed for serum collection and histological processing of the liver, lungs, musculature, and brain. Infectivity assessment by enzyme-linked immunosorbent assay (ELISA) revealed that the overall immunological pattern of infected mice tended to be towards the Th2 type response. Serum IgG1 antibody titers in infected mice were significantly higher than that of the uninfected control mice throughout the trial (P<0.05). On the other hand, no significant difference in titers of IgG3 antibody, an indicator for the Th1 type response, was observed between the infected and control mice, except at eight WPI (P<0.05). Pathogenicity was assessed semiquantitatively by comparing the mean number or diameter of inflammatory foci as well as histopathological changes in the liver, musculature, brain, or lungs of the infected mice and the control mice. Each hematoxylin and eosin (H&E) stained tissue section slide was examined under 100x magnification and 15 random fields were counted. Degree of inflammatory injury among the four organs was scored and categorized into four levels: normal (0), mild (1+), moderate (2+), and severe (3+). An index of inflammatory injury (mean score of experimental group/mean score of 10 control groups of 20 uninfected mice) of 2-3 is considered as moderate to severe, 1-2 as mild to moderate, and 0-1 as normal to mild. Histopathological changes were moderate to severe in the liver and lungs, mild to moderate in the musculature, and only normal to mild in the brain throughout the trial. It is noteworthy that apocrine-like change in epithelial cells of the bile duct was observed in most of the infected mice from eight WPI onward. Furthermore, larvae trapped by organized granulomas were found in soft tissue near the musculature at 12, 20, and 28 WPI. Altogether, not only were the infectivity and pathogenicity of the 14-month-cultured T. canis embryonated eggs retained, the hatched larvae were also capable of eliciting some special pathological changes in the murine host.     

Risk of Toxocara canis eggs in stray and domestic dog hair in Egypt

The aim of the study was to assess whether the hair of stray and domestic dogs in Egypt was contaminated with the eggs of the zoonotic parasite Toxocara canis, and also to identify risk factors for T. canis for contamination. Paired samples of hair and feces were collected from 53 stray and 47 domestic dogs, and hair samples were obtained from a further 11 stray and 9 domestic dogs. All samples were examined to identify T. canis eggs and, if eggs were found, their maturation stage. Eggs were identified in 26.6% of stray and 10.7% of domestic dog's hair samples. A significantly increased risk of embryonated T. canis eggs in hair samples was found in stray dogs (p=0.04), stray dogs had 3.18 (95% CI: 1.04-9.74) times the odds of having T. canis eggs present compared with domestic dogs. There was also a significant difference (p=0.02) between the mean quantity of eggs per gram in stray (77.6±6.54) and domestic (48.7±6.65) dog's hair. Fecal examination found a T. canis egg prevalence of 35.8% and 21.3% in stray and domestic dogs, respectively. As no domestic dogs which were positive from hair samples had negative fecal samples, this indicates that the presence of T. canis eggs in hair is probably due to self contamination. Two stray dogs had positive hair samples but negative fecal samples indicating that contamination may also be environmental. As both non-embryonated and embryonated T. canis eggs were found in the hair of domestic dogs, direct contact with dogs may be a potential risk factor for transmission of T. canis eggs to humans.     

Effect of fenbendazole on Toxocara canis larvae in tissues of infected dogs.

The effect of fenbendazole therapy was studied in six dogs fed 10,000 embryonated Toxocara canis eggs. At 47 days after they were fed T canis, four dogs were given fenbendazole in two divided doses totaling 50 mg/kg of body weight each day for 14 days. Two infected dogs were not given fenbendazole. All dogs were necropsied at the end of treatment and the foci were counted in the lungs; their skeletal muscles were digested in 1% trypsin for the recovery of larvae. The T canis larvae were not recovered from the skeletal muscle of the four infected dogs treated with fenbendazole; 15 and 42 larvae/100 g of skeletal muscle were recovered from the two nonmedicated infeected dogs. The number of grossly visible foci on surfaces of lungs in treated dogs was markedly less than in the nonmedicated infected dogs. The results indicate that fenbendazole might be effective in preventing prenatal infection in dogs.     

Hair coat contamination with zoonotic helminth eggs of farm and pet dogs and foxes

Infections of dogs with Toxocara canis and Echinococcus multilocularis pose an infection-risk particularly for contact persons. We examined specimens of hair coat and faeces of 124 farm dogs, 118 household dogs, 49 kennel dogs, 15 puppies from two litters, and 46 red foxes. Microscopically identified eggs of Toxocara or taeniids were further investigated by species-specific PCRs. In farm dogs, eggs of E. multilocularis or T. canis were identified in each 2.4% of faecal samples, eggs of T. cati (gastrointestinal passage) in 7.3%, respectively. Household dogs excreted eggs of T. canis (0.8%) and of T. cati (2.5%). In kennel dogs, eggs of T. canis (4.1%), but not of T. cati were detectable. Coat samples contaminated with eggs of Toxocara spp. were found from farm dogs (5.6%), household dogs (1.7%) and kennel dogs (2.0%). Taeniid eggs were isolated from the coat samples from only two farm dogs (1.6%); a molecular species determination was not achieved. In six intrauterinely infected puppies, Toxocara-eggs were found in 17/38 samples taken within six weeks. No intact Toxocara eggs could be isolated from the coat of nine puppies from a second litter 13 days after deworming. Of the 46 red foxes investigated (dissection and faecal samples) 13 (28.3%) were infected with E. multilocularis and 20 (43.5%) with Toxocara. Eggs of taeniids and Toxocara were found in 13% (in three cases confirmed as E. multilocularis) and 21.7%, respectively, of the coat samples. None of the retrieved Toxocara eggs in the coat samples were embryonated. Thus, an infection of humans through the transmission of E. multilocularis eggs after direct contact with dogs or foxes is conceivable, whereas a corresponding infection risk by Toxocara eggs must be critically challenged.     

Transmission trials, ITS2-PCR and RAPD-PCR show identity of Toxocara canis isolates from red fox and dog.

Toxocara canis isolates from dog and from red fox were compared in transmission trials and with molecular analysis using RAPD-PCR technique and comparison of the ITS2 sequence. After oral infection of bitches with 20,000 embryonated T. canis eggs of vulpine and canine origin, the vertical transmission to pup's was examined. All animals of both groups developed typical clinical symptoms of toxocarosis. The haematological, serological, parasitological and post mortem results showed no differences between both isolates except for the infectivity of T. canis stages in mice where the fox isolate showed a significant higher infectivity than the dog isolate. The RAPD-PCR showed a similarity coefficient of 0.95, similar to the range of intraspecific variation in Toxocara cati and Toxascaris leonina specimens as outgroups. The ITS2 comparison showed a 100% identity between both isolates with no intraspecific variations. Therefore, the study shows that the fox and the dog isolate of T. canis were identical in infectivity, transmission and molecular structure; a host adaptation could not be found and the fox has to be seen as a reservoir for T. canis infections in dogs. Considering the increasing number of foxes in urban areas the importance of helminth control in dogs is stressed.     

A critical look at the importance, prevalence and control of toxocariasis and the possibilities of immunological control

The visceral infection of humans with Toxocara canis is particularly prevalent in children and may cause a variety of symptoms that commonly persist for 6-24 months. The ocular infection usually causes permanent loss of visual acuity. Human infection is acquired by ingestion of embryonated T. canis eggs with contaminated dirt. Review of recent reports indicates that patent T. canis infection is widely prevalent in the general population of dogs all over the world (3-81%) and results in a substantial contamination of the ground (0.3-87%). The results of sensitive and specific serological tests suggest that about 7% of the clinically healthy human population of the United States, about 5% of that of Canada, and about 4% of that in Great Britain is infected with the parasite. Control of transmission of the parasite to man is often attempted by eliminating the infection in dogs, reducing the population of dogs and the environmental contamination with their feces, and educating the public about the zoonotic potential of toxocariasis. The evidence reviewed indicates that these methods are only marginally effective. Because T. canis relies on congenital and lactogenic transmission to persist in nature, only a procedure that effects the sustained killing of the reservoir larvae in the tissues of the bitch, or of newly-acquired parasites, is expected to be successful. Research with mice, rabbits and dogs demonstrated that prior infections of the host induce the development of protective immunity to reinfections. This procedure, however, leaves remnant populations of larvae from the immunizing infections that are resistant to anthelmintics and to the effect of prior irradiation. Hyperimmunization with partially-purified extracts of T. canis larvae induced 37% resistance to a challenge in mice when the extract was administered alone, and 76% resistance when administered with lipopolysaccharide adjuvant. Production of complete resistance, however, will probably require the prior control of the immunosuppression induced by the parasite. T. canis infections inhibit the production of homologous protective immunity and antibody responses to heterologous antigens, probably by interfering with the activity of helper T-cells, competing with protective antigens, and suppressing antibody synthesis. The evidence indicates, however, that an anti-T. canis vaccine to eliminate the parasite in dogs is feasible.     

Investigations into the prevention of prenatal and lactogenic Toxocara canis infections in puppies by application of moxidectin to the pregnant dog

Aim of the investigation was to examine whether two administrations of moxidectin to pregnant dogs could prevent pre-natal and lactogenic infections of puppies with reactivated Toxocara canis larvae. Four pregnant beagles, infected experimentally with 20 000 embryonated eggs of T. canis, were treated subcutaneously with 1 mg moxidectin per kg body weight on days 40 and 55 of pregnancy (5-13 days before parturition). One further dam and its puppies served as untreated control. Two applications of moxidectin completely prevented pre-natal and lactogenic infections in the puppies. Neither intestinal stages nor somatic larvae were found in the dams or their corresponding puppies. All puppies and dams of the treatment group remained coproscopically negative until 42 days after parturition. The administration of moxidectin did not show any side effects in the dams. None of the puppies of the treated dams showed any pathological abnormalities. In the untreated dam one adult and 26 somatic larvae of T. canis were detected at necropsy. All puppies of the untreated dam showed a patent T. canis infection from day 28 post-natum (p.n.); 296 pre-adult and adult stages of T. canis were spontaneously eliminated and 51 intestinal stages and five somatic larvae of T. canis were recovered at necropsy. In contrast to the puppies of the treated dams all negative control puppies showed blood eosinophilia after parturition and elevated liver enzyme levels.     

Effects of milbemycin on adult Toxocara canis in dogs with experimentally induced infection

To determine the efficacy of a formulation of milbemycins in treating patent infection with Toxocara canis, 8 male and 7 female, 10-week-old, ascarid-free Beagles each were given 125 embryonated eggs of T canis. All dogs developed patent infection within 56 days. On post-infection day 70, the dogs were assigned to 1 of 3 groups of 5 dogs each; members of 1 group were given a placebo, while dogs of the other 2 groups were given either 5.68 or 34.08 mg of the milbemycin formulation, respectively. In both groups of dogs given the drug, the number of eggs passed per gram of feces decreased precipitously. However, a few eggs still were found in the feces of several dogs of each group on the day of necropsy (postinfection day 75). Worms or fragments of worms were passed by the treated dogs from the day of treatment until the day on which necropsy was performed; however, most worms were passed during the first 2 days after treatment. At necropsy, only dogs of the control group were found to harbor adult T canis.     

Influence of murine Toxocara canis infection on plasma and bronchoalveolar lavage fluid eosinophil numbers and its correlation with cytokine levels

Toxocara canis is a nematode of the Ascaridae family that normally parasites the small intestine of canid species. Humans are accidentally infected upon ingestion of embryonated eggs, and can manifest several clinical alterations such as fever, hepatomegaly, splenomegaly, respiratory symptoms, muscle pain and anorexia. In the present work, we investigated the kinetics of tissue distribution of L2 larva in lungs, liver, kidney, brain, skeletal muscle and myocardium. Also, we analyzed the blood and bronchoalveolar lavage fluid (BAL) for levels of IL-6, IFN-gamma, eotaxin and Regulated on Activation Normal T Cell Expressed and Secreted (RANTES) in experimental murine T. canis infection. We observed liver, lung and kidney lesions correlated to larva migration as early as the first day of infection. After the seventh post-infection day, larva could also be detected in brain, skeletal muscle and heart, as an indicator of biphasic migration pattern. Increased inflammatory activity was detected in BAL and plasma of infected animals, as was an intense eosinophil migration associated with an increase in the levels of all the cytokines studied. In conclusion, our results establish a tight correlation between tissue lesions caused by larva migration and increased plasma levels of pro-inflammatory and eosinophil chemotactic cytokines. Thus, murine T. canis infection may prove to be useful in understanding the role of cytokines in infection.     

雏半番鸭呼肠孤病毒的致病性

从鸭体、禽胚和细胞 3个方面探讨了雏半番鸭呼肠孤病毒 FZ2 株的致病性。经试验表明 ,在实验室条件下 ,该株病毒可导致雏番鸭、雏半番鸭发病、死亡 ,对雏番鸭的致死率为 14 .3%～ 4 1.7% ,对雏半番鸭的致死率高达 38.5 % ,且死亡鸭表现出与自然感染呼肠孤病毒病死的雏番鸭、雏半番鸭相同的病变 ;人工感染幸存鸭大多生长发育明显受阻。该株病毒经尿囊腔途径接种 ,对番鸭胚、半番鸭胚、北京鸭胚、SPF鸡胚的致死率分别为 10 0 %、96 %、2 8%和 0 ,致死鸭胚的肝脏、脾脏表面见白色坏死点。经蛋传试验表明 ,该株病毒有可能经胚蛋垂直传染。以该株病毒在番鸭胚成纤维细胞 (MDEF)上连续传接 10代 ,结果细胞病变 (CPE)仍不明显 ,表明其不易适应 MDEF。由此可见 ,该株雏半番鸭源呼肠孤病毒具有较强的致病力     

High pressure processing treatment prevents embryonation of eggs of Trichuris vulpis and Ascaris suum and induces delay in development of eggs

High hydrostatic pressure processing (HPP) is an effective non-thermal treatment used to inactivate pathogens from a variety of food and food products. It has been extensively examined using prokaryotic organisms and protozoan's but has had limited study on metazoans. Treatment using HPP has been shown to be effective in inactivating nematode larvae in food and preventing embryonation of Ascaris suum eggs. We conducted experiments using eggs of the canine whipworm Trichuris vulpis collected from naturally infected dogs and A. suum eggs from naturally infected pigs. We observed a delay in development of eggs of T. vulpis in a preliminary experiment and conducted 2 experiments to test the hypothesis that appropriate HPP levels can induce a delay in embryonation of nematode eggs. In experiment 1, nonembryonated T. vulpis eggs in tap water were packaged in sealable bags and exposed to 138-600 megapascals (MPa; 1 MPa=10 atm=147 psi) for 60s in a commercial HPP unit. In a second experiment, nonembryonated eggs of A. suum were exposed to 138-600 MPa and treated for 60s in the same commercial HPP unit. Embyronation of T. vulpis eggs was delayed by 4 and 5 days for eggs treated with 207 and 241 MPa but eventually eggs developed and the numbers of embryonated eggs was similar to controls on day 55. Embryonation of T. vulpis eggs treated with 345 or 350 MPa was delayed by 9 days and never reached more than 5% of eggs embryonated. On day 55 post treatment, 95% of control nontreated T. vulpis eggs were embryonated, 100-65% of eggs treated with 138-276 MPa were embryonated, a maximum of 5% of eggs treated with 345-350 MPa were embryonated, and 0% of eggs treated with ≥ 400 MPa were embryonated. T. vulpis eggs treated with ≥ 400 MPa did not undergo cell division. Embryrnation of A. suum eggs was delayed by 4, 10, and 16 days for eggs treated with 207, 241, and 250MPa, respectively, compared to nontreated control eggs. A. suum eggs treated with 207 MPa eventually embryonated to similar % embryonation values as controls and 138 MPa treated eggs but eggs treated with 241 or 250 MPa were always <5% embryonated. A. suum eggs treated with ≥ 300 MPa did not undergo cell division. On the final day of examination at day 56 after treatment, the % of embryonated eggs was 92% nontreated controls, 94% treated with 138 MPa, 84% treated with 207 MPa, 2% treated with 241 or 250 MPa, and 0% treated with 276, 200, 345, 400, or 414 MPa, respectively.     

新城疫病毒在鸡胚不同组织增殖的研究

不同新城疫病毒Ｆ４８Ｅ８、Ｎ－７９、ＬａＳｏｔａ和分离株Ｘ以１∶１００００稀释接种９日龄ＳＰＦ鸡胚,每胚０．２ｍｌ,结果发现,Ｆ４８Ｅ８和分离株Ｘ毒力较强,可在５０小时左右致死鸡胚,ＬａＳｏｔａ和Ｎ－７９较弱。Ｆ４８Ｅ８和Ｘ株接种鸡胚的肌肉、肝脏、脑和尿囊液均有大量病毒存在,而Ｎ－７９和ＬａＳｏｔａ只在尿囊液中有大量病毒存在,胚体病毒极少。     

Immunity of swine to Ascaris suum

Swine were hyperimmunized to Ascaris suum by giving multiple oral inoculations of embryonated eggs. Sera and lymphocyte lysate from these pigs were administered parenterally to 4-week-old pigs. The latter animals were no more resistant to larval migration than control pigs receiving sera or lymphocyte lysate from non-immunized pigs. Other pigs were infected with transmissible gastroenteritis (TGE) virus, allowed to recover and challenged with embryonated ascarid eggs. They likewise were no more resistant to ascarid larval migration than control pigs.     

Failure of Heterakis bonasae to transmit Histomonas meleagridis

Studies were conducted to determine whether Heterakis bonasae eggs from bobwhite quail infected with Histomonas meleagridis would transmit histomoniasis to turkeys. Fifteen helminth-free bobwhites were inoculated per os with embryonated H. bonasae eggs. Each bobwhite was then infected with H. meleagridis via rectal inoculation. Bobwhites that developed cecal lesions rarely retained mature H. bonasae. H. bonasae eggs recovered from bobwhites exposed to or known to have concurrent H. meleagridis infections were inoculated per os to eleven helminth-free turkeys. None of the turkeys developed H. meleagridis infections.     

Contamination of dog hair with eggs of Toxocara canis

Toxocara canis, the common intestinal nematode of dogs and foxes, is the parasite responsible for human toxocarosis. It has recently been shown that dogs may harbour eggs of the parasite in their fur. To further investigate this claim a population of 100 stray dogs was examined to establish the prevalence and intensity of adult toxocaral worm infection in the intestines and eggs harboured in the hair. A novel method of washing the eggs from the hair was used. Sixty-seven percent of dogs were found to have T. canis eggs on their hair with a mean egg retrieval of nearly 584 eggs per gram from positive dogs. The age of the dog was found to be the only significant factor to influence the prevalence and intensity of eggs, with 95% of all the eggs recovered found on puppies. Thirty-nine percent of dogs were found to have adult T. canis worms in their intestine, although a significantly higher percentage of puppies (80%) were infected with worms than adults (22.5%). Puppies also had more worms per infection than adults and have a strong positive correlation between egg and worms numbers whereas adults did not. These studies show that stray dogs, particularly puppies, potentially harbour considerable numbers of eggs on their hair, at densities far higher than those reported in the soil or the general environment.