Helminth and protozoan parasites in dogs and cats in Belgium

This study investigates the level of helminthic and protozoal infestation over the last 10 years in strays, well-cared-for dogs and cats. Determination of the prevalence of infections was based either on faecal examination or on worm counts at necropsy. Of 2324 faecal flotations (NaCl sp.gr. 1.20) of stray dogs, 34.2% had eggs or proglottids of one or more worm species consisting of Toxocara canis (17.4%), Toxascaris leonina (10.1%), Uncinaria stenocephala (11.4%), Trichuris vulpis (7.0%) and cestodes (2.1%). Isospora oocysts were observed in 5.2% of the dogs. The data on the distribution of the various worm species in the positive dogs indicate that T. canis eggs were by far the most common (50.9%). Necropsy data from 212 infected dogs indicate that 38.9% were infected with T. canis and 33.7% with T. leonina. The overall prevalence of worm infestation of 246 well-cared-for kennel dogs, based on worm egg counts by the McMaster technique, was 36.1%. Of 30 feline faecal samples examined by flotation, 83.3% were positive for parasites, including Toxocara cati (60%), Ancylostoma tubaeformae (36.6%), Taenia (Hydatigera) taeniaeformis (20%) and coccidia (30%). Toxocara cati was the most frequently found worm species at the necropsy of 25 cats (52%). Toxoplasma was not observed.     

Toxocara eggs shed by dogs and cats and their molecular and morphometric species-specific identification: is the finding of T. cati eggs shed by dogs of epidemiological relevance?

Intestinal infections with Toxocara cati and Toxocara canis in their definitive host (felids and canids, respectively) are diagnosed by egg identification in faeces using coproscopical techniques. The Toxocara species is assumed to comply with the species from which the examined faeces were obtained, i.e. T. cati in cats and T. canis in dogs. We isolated and measured Toxocara eggs from faecal samples of 36 cats and 35 dogs from Switzerland and identified the Toxocara species by PCR. Amongst the isolates originating from dogs, 24 (68.5%) were determined as T. canis and 11 (31.5%) as T. cati. In all samples originating from cats, only T. cati was identified. Based on PCR identification, eggs of T. canis (n=241) and T. cati (n=442) were measured, revealing statistically significant different (p<0.001) mean sizes of 62.3 by 72.7 μm for T. cati and 74.8 by 86.0 μm for T. canis eggs. Considering that coprophagy is not unusual for dogs, a considerable percentage of Toxocara infections coproscopically diagnosed in dogs, as well as assumptions on anthelminthic resistance in regularly treated dogs, might in fact relate to intestinal passages of eggs following the uptake of other animals' faeces.     

Prevalence of Toxocara spp. and other parasites in dogs and cats in Halifax, Nova Scotia.

Several cases of visceral larva migrans syndrome in children led to an investigation of the ova of Toxocara spp. and other species in stool specimens from stray dogs and cats in Halifax, Nova Scotia. Fecal samples from 474 stray dogs and 299 stray cats were examined. Ova of Toxocara canis or cati were present in stools from 26.6% of the dogs and 25.1% of the cats. In dogs the prevalence of Toxocara canis was noticeably greater in puppies (56.1%) than in mature animals (11.9%).     

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.     

Ascarid infections of cats and dogs

The ascarids Toxocara canis, Toxocara cati, and Toxascaris leonina are probably the most common gastrointestinal helminths encountered in small animal practice. Both T. canis and T. cati can cause serious disease in kittens and puppies; T. leonina is generally less pathogenic. Prenatal transmission assures that virtually all puppies are born infected with T. canis. Transmammary transmission is probably the major route of infection for kittens with T. cati. In addition, all three species of worm produce resistant eggs and use paratenic hosts to facilitate transmission. Much is now known about the complex biology and life history of T. canis. However, many questions, such as those concerning the mechanisms of larval survival within host tissues and of larval reactivation and migration during pregnancy, await further study. The mechanism of resistance to ascarid infections in cats and dogs has not been clearly defined. Ascariasis is traditionally thought to be a disease of young animals, with older animals being considered immune. However, at least in the case of T. canis, adult dogs can be repeatedly infected. A wide range of anthelmintics is available with extremely high efficacy against patent ascarid infections. The problem of prenatal infection with T. canis may be overcome by strategic use of the newer benzimidazole-carbamates, and the production of ascarid-free puppies now seems possible. However, complete larvicidal activity against somatic stages has not been convincingly demonstrated. Visceral larva migrans-like syndromes are now being recognized in dogs and cats. In addition, visceral larva migrans in children due to T. canis continues to be a significant zoonotic disease in North America and underscores the need for the veterinary profession to control ascarid infections in cats and dogs at every opportunity.     

Ascarid nematodes in domestic and wild terrestrial mammals

The biology of the ascarid nematodes has been discussed in the context of their important economic role in farm animals, pet animals and zoo animals with special attention to carnivores and primates. In farm animals, infection with the most common roundworm of horses (Parascaris equorum) and swine (Ascaris suum) depend on many factors such as environmental conditions (larval development in the egg and egg survival), age of the host, breed, husbandry system, hygiene and treatment schedule. The monoxenic ascarids Toxocara canis and T. cati are the most important nematodes in carnivorous animals (dogs, cats, foxes) and carnivores in the zoo. In the period of March 2000 till March 2001, 57.1% of examined representatives of Felidae, Ursidae and Canidae in the Zoological Garden of Wroc?aw were found to be infected with ascarids (T. canis, T. cati, Toxascaris leonina). The prevalence of T. canis in the Canidae was 66.7%, of T. cati in the Felidae was 14.3%, while 57.1% of the Felidae carried T. leonina infection. Ascaris lumbricoides, a typical parasite of primates, was found in some gorillas, chimpanzees and orang-utans during parasitological survey.     

Differentiation of Toxocara canis and T. cati eggs by light and scanning electron microscopy

In this study, we investigated the morphological identification of Toxocara canis and T. cati eggs on the basis of light and scanning electron microscopic (SEM) observations. T. canis and T. cati eggs used in this study were recovered from the uteri of respective gravid female worms. Measurement of egg size was not helpful in the differentiation of these species, because approximately 90% of eggs measured were of similar size. Using SEM, we were able to differentiate T. canis eggs from T. cati eggs based on their respective characteristic surface structures. Both species have subspherical eggs with markedly pitted surfaces like those of a golf ball, but the surface pitting in T. canis is more coarse than that in T. cati. In this study, however, these differences were not absolute, as 16% of T. canis and 29% of T. cati eggs showed surface pitting that was uncharacteristic of their species. Of the 16% of T. canis eggs that could not be differentiated by surface structure, 3% had pitting resembling T. cati, and the remaining 13% showed intermediate type surface pitting. Similarly, 5% of T. cati eggs resembled T. canis, and 25% of these were of intermediate type. Light microscopic observation yielded results similar to those of SEM, indicating that light microscopy is also a useful tool for the identification of Toxocara eggs.     

Distribution of Toxocara infection in the environment and in definitive and paratenic hosts in Estonia

The aim of the study was to elucidate the distribution and possible transmission routes of Toxocara spp. infection in Estonia. Out of 454 faecal and sand samples collected from park lawns and sandpits in the town of Tartu, 19 were Toxocara positive (4.2%). Out of the 45 sandpit samples 17.8% were Toxocara positive. Cat faeces was found in 21 sandpit samples. Parasitological necropsies were performed on 41 euthanised stray dogs and 27 cats in the Tallinn Dog Home. Additionally, 13 wild free-roaming brown rats (Rattus norvegicus) were captured from the Tallinn Dog Home territory, necropsied and studied for the presence of Toxocara larvae. Toxocara canis adults were found in 14.6% of the dogs and Toxocara cati (syn. mystax) adults in the small intestines of 48.2% of the cats examined. Larval infection was detected in the kidney and liver in 5 dogs (12.2%). Our study demonstrated only low-level larval Toxocara infections in adult dogs. Toxocara larvae were not found in cats and brown rats. According to the results of this study, cats more often carry Toxocara infection than dogs. Under our conditions, stray and free-roaming cats are the main contaminators of the environment with Toxocara eggs. Children playing in sandpits are the main risk group for larval toxocarosis.     

Echinococcus multilocularis and Toxocara canis in urban red foxes (Vulpes vulpes) in Brussels, Belgium

During the last decades, European red foxes (Vulpes vulpes) have been implicated in the transmission of several viral or parasitic pathogenic agents to domestic animals and humans. In urban areas, risks of zoonoses transmission are likely to increase as a result of a higher rate of intra- and inter-species contacts. Foxes occur on 35% of the Brussels-Capital Region area and local densities reach up to 4 family groups per square kilometre. According to the directive 2003/99/ECC, a first survey for the presence in foxes of Echinococcus multilocularis and Toxocara canis was conducted in Brussels from 2001 to 2004. None of 160 foxes were found to be infected with E. multilocularis and 24 of 134 foxes were found to be infected with T. canis. Considering numbers of examined foxes, the sensitivity and the specificity of tests used for diagnosis, the 95% credibility intervals for the true prevalence of E. multilocularis and T. canis were estimated in a Bayesian framework to be 0 to 1.87% (median value of 0%) and 12.7 to 26% (median value of 18.7%), respectively. For T. canis, a significantly higher risk to be a carrier occurs in cubs and a significantly lower risk in adults.     

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.     

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.     

Echinococcus multilocularis in dogs from two French endemic areas: no evidence of infection but hazardous deworming practices

The life cycle of the zoonotic parasite Echinococcus multilocularis is predominantly sylvatic, involving foxes as definitive hosts infected by predation of rodents, the intermediate hosts. The North-Eastern French departments of Meuse and Haute-Sa?ne are highly endemic, with an estimated fox prevalence of 41% and 36% respectively. Although most of the parasites' biomass occurs in foxes, domestic dogs can also be infected, leading to a major risk of human infection due to the close proximity of dogs and owners. In the present study, dog faeces were collected after praziquantel treatment provided by veterinarians. In all, 860 faecal samples were collected throughout Meuse (n=493) and Haute-Sa?ne (n=367). Intestinal helminth eggs were isolated from the faeces using a flotation technique and observed by microscopy. Parasite species were identified in samples positive for taeniid eggs by sequence analysis after PCR amplification. To study the factors associated with infestation, each sample was linked to a questionnaire filled in by the dog owners. Taeniid eggs were observed in seven faecal samples (0.8%) but none of them were positive for E. multilocularis. Thus, the apparent prevalence of E. multilocularis in dog populations is lower than 1.00% for Haute-Sa?ne and lower than 0.75% for Meuse. In Haute-Sa?ne, a high proportion of dogs observed suspected preying on rodents were not dewormed monthly. In endemic areas, these dogs must be considered at risk of transmitting E. multilocularis to humans.     

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.     

Detection of patent infections of Echinococcus granulosus ("sheep-strain", G1) in naturally infected dogs in Kosovo

A survey was carried out to assess the occurrence of canine echinococcosis in naturally infected dogs in Kosovo. Using the flotation-ovassay technique, taeniid eggs were found in 23 (7.5%) out of a total of 305 dogs. Eggs from other helminths were detected as well: hookworms 139 (45.5%), Trichuris sp. 87 (28.5%), Toxocara sp. 42 (13.7%), Toxascaris leonina 21 (6.8%) and Dipylidium caninum eight (2.6%). From 21 of the 305 samples (6.9%), taeniids eggs could be collected. Using PCR primers specific for Echinococcus granulosus ("sheep strain", G1), four of these samples (1.3%) resulted positive. The E. granulosus isolates originated from each one stray dog, hunting dog, sheepdog and pet dog. A semi-quantitative analysis showed low to moderate egg counts (2-10 per 1 g faeces) in dogs positive for E. granulosus ("sheep strain", G1) whereas specimens with high (11-20) or very high numbers (> 20) of taeniid eggs were negative in the E. granulosus PCR. Using specific primers for the detection of E. multilocularis, all samples containing taeniid eggs were negative. This is the first report on identification of E. granulosus in dogs from Kosovo where human cystic echinococcosis is a significant medical problem.     

Echinococcus multilocularis infections in domestic dogs and cats from Germany and other European countries

A cross-sectional survey was conducted to estimate the prevalence of Echinococcus multilocularis and E. granulosus infections in domestic dogs and cats from Germany and other European countries. Faecal samples of 21,588 dogs and 10,650 cats routinely submitted to a private veterinary laboratory between June 2004 and June 2005 were examined using the ZnSO(4)-NaCl flotation method. Taeniid eggs were detected in 54 (0.25%) and 37 (0.34%) of the canine and feline faecal samples, respectively. Taeniid eggs were separated and subjected to a DNA preparation and a modified two-step PCR for the detection of Echinococcus spp. based on mitochondrial 12S rRNA genes. PCR products from Echinococcus-negative but cestode-positive reactions were cloned and sequenced to determine the Taenia species. E. multilocularis DNA was specifically amplified in 43 (0.24%) and 25 (0.23%) of the samples from dogs and cats, respectively. E. granulosus DNA was not detected in any sample, while, E. multilocularis-positive samples were detected in dogs from Germany only, those of cats originated from Germany, Denmark and The Netherlands. The prevalence of E. multilocularis egg-positive canine samples was significantly higher in southern (0.35%) than in northern Germany (0.13%). In contrast, no significant regional difference was observed in cats from Germany. Taeniid eggs from Echinococcus-negative samples and from a few samples with macroscopically detected Taenia sp. proglottids were identified as eggs of T. crassiceps (n=8), T. martis, T. serialis, T. polyacantha, T. taeniaeformis and T. pisiformis in dogs (n=1 of each) and T. taeniaeformis (n=11) in cats. The spectrum of cestodes detected in domestic dogs and cats indicate the consumption of small rodents as infection source. The high proportion of E. multilocularis-positive samples, suggest domestic dogs and cats as a possible source of E. multilocularis infection for humans.     

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.     

Prevalence and intensity of Echinococcus multilocularis in red foxes (Vulpes vulpes schrencki) and raccoon dogs (Nyctereutes procyonoides albus) in Otaru City, Hokkaido, Japan

A survey was done in an attempt to investigate the epidemiological status of Echinococcus multilocularis in red foxes and raccoon dogs in Otaru city from June to September 1999. Sixty-seven red foxes (Vulpes vulpes schrencki) and 13 raccoon dogs (Nyctereutes procyonoides albus) were captured, and postmortem examinations were conducted with them. Thirty-eight red foxes (56.7%) and 3 raccoon dogs (23.1%) were found to be infected with E. multilocularis. The total biomass of E. multilocularis in all infected red foxes and raccoon dogs were 2,817,000 and 1,515 worms, respectively. Nine of the infected red foxes harboring more than 100,000 worms accounted for 90.6% of the total biomass. No significant differences in the prevalence were observed between male and female, and juvenile and adult. However, the worm burden was higher in juvenile than in adult foxes. In one of the infected raccoon dogs, mature worms and eggs of E. multilocularis were found in the intestine and fecal sample, respectively. This result suggested that the raccoon dogs are probably playing a small role in the egg contamination of the environment. The validity of coproantigen ELISA for diagnosis of foxes was confirmed by comparing the results of autopsy, egg examination and coproantigen ELISA using rectal fecal samples.     

Estimation of canine intestinal parasites in Córdoba (Spain) and their risk to public health

The prevalence of gastrointestinal parasites in dogs was studied in the province of Córdoba (southern Spain), with special attention to those parasites that can be transmitted to man. The experiment was completed with the examination of soil samples from public parks and city gardens. The study was carried out over a population of 1800 animals entered in the Control Animal Centre (CECA) by coprological methods, and within this group, 300 dogs were sacrificed and necropsied. The prevalence of any intestinal parasitic infection was 71.33%. The following parasites of the gastrointestinal tract were recorded: Isospora canis (22%), Isospora (Cystoisospora) spp. (10.22%), Sarcocystis (2.5%), Hammondia/Neospora (1.94%), Giardia canis (1%), Dipylidium caninum (13.2%), Taenia hydatigena (7.66%), Taenia pisiformis (4%), Uncinaria stenocephala (33.27%), Toxascaris leonina (14.94%), Toxocara canis (17.72%) and Trichuris vulpis (1.66%). Related to public health, it is important to point out the presence of T. canis only in puppies younger than one year and Uncinaria, more frequent in adult dogs. Soil samples of parks revealed the presence of eggs of Toxocara, and it suggests the existence of real risk for human infection.     

Prevalence of chlamydia, toxoplasma, toxocara and ringworm in farm cats in south-west England

The prevalence of infection with Chlamydia psittaci, Toxoplasma gondii, Toxocara cati and Microsporum canis was examined in 51 cats on 22 sheep farms in the Bristol area. Serum antibody to C psittaci and T gondii was present in 45 per cent and 47 per cent of cats, respectively. At the time of sampling C psittaci was isolated from 6 per cent of the cats, T cati was identified in 63 per cent of faecal samples but neither T gondii nor M canis was isolated. When examined according to the farm of origin, 22.7 per cent of farms had cat populations with no evidence of infection with C psittaci or T gondii. Of the remainder, 45.5 per cent supported cat populations with evidence of both infections and 31.8 per cent had evidence of T gondii infection alone. None of the farms had cat populations with evidence of C psittaci infection alone. Two of the cats infected with C psittaci were excreting viable organisms in the faeces. The possible significance of this to the epidemiology of ovine enzootic abortion is discussed.     

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.