DEPARTMENT OF ANIMAL AND ENVIRONMENTAL BIOLOGY,

FACULTY OF SCIENCE, IMO STATE UNIVERSITY OWERRI,

P.M.B 2000 OWERRI, NIGERIA

ABSTRACT

In a seven months (February to August, 2002) prevalence study of intestinal helminth parasites of dogs in the New Owerri area of Imo State, Nigeria, using both direct and concentration methods six helminth parasites were recorded. These included Hookworm, Strongyloides sp, Toxocara canis, Trichuris vulpis, Diphylidium caninum and Taeniid eggs. Of the 554 faecal specimens of dog sampled, 454 (81.9%) were infected with one or more helminth parasites. Hookworm infections had the highest prevalence (22.2%), followed by Taeniid eggs (19.4%) with Strongyloides sp as the least (12.9%). While there was no significant variation amongst the prevalence of the helminth parasites and study areas (P>0.05), male dogs were significantly more infected than female dogs (P<0.05). Younger animals less than 36 months of age had significantly higher prevalence than the older animals (P<0.05). Infection was independent of the breeds of dog (P>0.05). The public health implications of some of the parasites encountered as well as lapses on the veterinary services in the new Owerri area are discussed.

Available literature on the endoparasitic fauna of dogs in Nigeria are limited to most work done in Western region. These include those of Idowu et al (1977), Olufemi and Bobade (1979), Oduye and Otesile (1977) as well as Nwoke (2000, 2001).

In northern Nigeria, Dada and Belino (1979) reported on the prevalence and public health significance of helminth ova in dog faeces deposited on the streets of Zaria while Abanobi and Anosike (1994) recorded a prevalence of 64.7% amongst feacal deposits of dogs examined in the river Hawal valley, Nigeria.

In the entire southeastern Nigeria especially Imo State where dogs are bred in large numbers, aspects of intestinal helminth parasitism is very scanty (Anosike et al 2000). The present study is to fill this information vacuum, assess the danger associated with free-roaming dogs and strengthen the strategy to promote public enlightenment on the danger of strayed dogs and the importance of taking dogs for appropriate care.

This study was carried out between February and August 2002. The study area is a newly created Estate in Owerri Urban called World Bank-assisted Housing Estate in Owerri West Local government area of Imo State. The estate which was located about 7 kilometers from Owerri Municipal council was created about eight years ago. The inhabitants are mainly Igbos, Calabar people and few foreigners.

World Bank-Assisted Housing Estate comprises of three areas mainly: Area l, Area M and Area N. the estate has only one market, one Catholic Church and few other Church denomination buildings. Most houses are of same construction styles which normally are occupied by a single house hold. About 1000 and 150 completed and uncompleted houses respectively exist in the area.

For security purposes and other reasons, half of these occupied houses have one or two dogs. Some of these dogs are found in market place, corners of roads and play grounds of children.

Prior to the sample collection, dog owners in the area were duely informed on the need for the investigation. Efforts were made to identify various faecal specimens against dogs that defecated them. Thus, this really helped to sex the specimen. However this was not easy. Most of the specimens collected were labelled against the dogs seen or in most cases, the dog owners assisted the team.

The respective ages and species of various dogs were collected from the owners. Most houses showed their dogs birth certificates issued from vatenary clinic centers.

Collected samples were usually examined soon after collection. However, if not examined the same day, the collected samples were preserved in 4% formalin for late observation.

Both direct and concentration methods of Anosike et al (2002) were adopted. The eggs (ova) as well as larvae were also identified and counted.

Six helminth parasites namely: Hookworm, Strongyloides sp, Toxocara canis, Trichuris vulpis, Diphylidium caninum and Taeniid eggs were recovered. Of the 554 faecal specimens sampled, 454 (81.9%) were infected. Specific rates of occurrence of the various helminth parasites are shown in table 1. Four of the six helminth parasites encountered are nematodes, two cestodes while there was no trematode recovered. Hookworm infection has the highest occurrence (22.2%), followed by Taeniid eggs (19.4%) while Strongyliodes sp had the least occurrence (12.9%).

n 454 (infected)

Three study locations were sampled for the presence of helminth parasites of dogs in the new Owerri, Imo State. These are areas L, M, and N. In area l, a total of 205 specimens were examined, 165 (80.5%) were infected. In area M, 149 (83.2%) out of 179 specimens harboured helminth parasites while 140 (82.45%) of the 170 faecal specimens had helminth parasites.

The sex-related prevalence of helminth parasites of dogs in the study area is shown in table 2. Of the 554 specimens sampled, 304 and 250 were males and females respectively. Of these, 267 (87.8%) and 187 (74.8%) males and females were infected respectively. In area l, N, and M, more males than females were infected. A chi-square analysis showed that males were significantly highly infected than female dogs (P<0.05).

Table 3 depicts the age –related prevalence of helminth parasites of dogs in the study area. The ages of dogs were categorized mainly into two groups. Those less than 36 months and those greater than 36 months. Of the 554 dogs specimen sampled, 388 and 166 belonged to the 0-36 months old and 37 months and above age respectively. Prevalences of 87.1% and 69.9% were recorded for dogs within the 0-36 months old and 37 months and above age groups respectively.

Statistical analysis showed that younger animals less then 36 months of age had significantly higher prevalence than the older animals (X_23df = 23.34 at P<0.05). All the various breeds of dogs were infected (table 4). Infection of dog was independent of breed (P>0.05).

TABLE 3: AGE-RELATED PREVALENCE OF HELMINTH PARASITES OF DOGS

This study on the parasitism of dogs in the new Owerri area of Imo State Nigeria shows that dogs of different age groups, breeds as well as sexes harbored various types of helminthes parasites. Six different helminth parasites were encountered. This observation is similar to the reports of Olufemi and Bobade (1979) in Ibadan, Dada and Belino (1979) in Zaria, Onwuliri et al (1993) in Jos, Thompson et al (1986) in a Caribbean community. Idowu et al (1977) gave a comprehensive three-year analysis of parasitic diseases of dogs and cats in Ibadan Nigeria. They showed that nematodes are the predominant helminths involved in dog parasitism, similar to the results of this study. Four of the six helminths recovered during this study are nematodes with hookworms, Strongyloides and Toxocara canis predominating. This observation could have bearing on the life cycle pattern of these parasitic nematodes which could be through per os, per -cutans or vertical transmission. These are major survival strategies exhibited by parasitic nematodes (Onwuliri et al 1993).

There was no significant differences in the prevalence of helminth parasites of dogs and the various study locations. This similarity in the prevalence of these parasites regarding study locations could be attributed to the nature of the different environments. The areas are similar to each other in microecology, behaviour of dog owners as well as indiscriminate defeacation by both dogs and children in the area.

Observations into the sex-related prevalence of dogs showed that males were significantly infected than the females. Male dogs have higher free-ranging than females. This is in line with the reports of Idowu et al (1977) in Ibadan area of Nigeria and Onwuliri et al (1993) in Jos Plateau. They attributed such observations to both immunological and hormonal factors inherent in the dogs. However, further studies are needed to elucidate the major factors responsible for sex-dependent prevalence observed herein.

Animals below 36 months of age had more infections than the older animals. This is indeed expected considering the fact that most infections especially with hookworms could be through vertical transmissions. It is also plausible that the puppies could get infected during the first ten days of delivery (Myazaki 1991). The younger animals are heavy feeders and a lot more viral than the older animals that are less voracious and active. Thompson et al (1986) in a Caribbean community and Dada & Belino (1979) in Zaria as well as Anosila et al (2002) in the Ebonyi Benue River Valley also subscribed to this observation.

The existence of some of these helminth parasites amongst the sampled dogs in the new Owerri Area of Imo state, Nigeria has some public health implications. Naturally, there are links between dog parasitism and transmission of diseases, including zoonosis. Dog infection can easily be transmitted to man. This becomes necessary in view of recent trend of increased number of free-roaming dogs used primarily for house security. Besides, to some, dog meat is a delicacy.

The presence of T. canis amongst dogs in this study location is significant. When it is parasitic in humans, it causes "larva migrans", being unable to mature and migrate as a larvae into various organs of the human body. T. canis causes Toxocariasis in dogs and cats. It is worldwide. In endemic areas, dogs especially those kept outdoors are frequently infected (Miyazaki 1991). As noted by Anosike et al (2002), pups are infected not only by ingesting the matured eggs in the soil or the third-stage larvae in the paratenic host, but also by ingesting larvae parasitic in the dam through her placenta or milk. They observed that as the dam licks her pup’s faeces for about 10 days after delivery, she might be infected occasionally by ingesting immature worms in the faeces. Humans are infected mainly by swallowing mature eggs. In addition, eating the meat of a paratenic host may result in intake of larvae hidden therein. For prophylaxis, it is most important to avoid swallowing mature eggs. This being so, the habit of washing hands well after playing \with dogs or in a sand pit is recommended. Considering the fact that children in these areas plays in the various sandpits available which as well is a common place of defecation for dogs, infective ascarid eggs abound. This calls for thorough and careful cooking of meat and liver before eating as Miyazaki (1991) noted three cases of this infection considered to be caused by eating the chicken and cattle liver raw. It is also recommended that sufficient care should be taken to treat dogs by their owners and dispose properly their faeces in order to prevent dispersal of Toxocara eggs. It is especially necessary to be careful when a dog is kept indoors.

D. caninum was also encountered during the study. It is usually known as the "dog tapeworm", because of wide distribution among dogs. To prevent this infection in man, the faeces of dogs be properly disposed off. D caninum has been recorded for stray dogs in Zaria, Nigeria (Dada and Belino 1979), in the Ebonyi / Benue river valley southeastern Nigeria (Anosike et al 2002) as well as elsewhere in Bermuda (Williams and Menning 1961).

The major root of infection by Strongyloids spp being the cutaneous invasion by females of parasitic generation (f-from females) larvae from wet soil. Therefore contact of bare skin with the soil should be avoided.

George and sprinkle (1974) documented a case of human strongyloides apparently contacted from an asymptomatic colony of dogs. There should be public enlightenment campaign by sanitary Health officers on the dog parasitism in both rural and urban settings. Indeed, the public should be health educated on the dangers of using dogs as house pets or security guards.

Presently in the new Owerri area of Nigeria canine health management is poor as dog owners rarely sought for professional advice similar to the observations of Abanobi and Anosike (1994); Anosike et al (2002). There are lapses on the veterinary services in the new Owerri area in particular and Nigeria in general. Because of the number of dogs in most households in Nigeria and their co-habitation with man in several households, dogs have been closely tied with the health status of many communities (Abanobi and Anosike 1994). Therefore, an area of community health that can plausibly be influenced by high dog population within communities is the risk of parasitic disease in which dogs are implicated as intermediary or collateral host.

The aforementioned observations therefore are of special implications for both veterinary and community health care service delivery in Nigeria. This calls for good personal hygiene, adequate environmental sanitation, public health education as well as employing prophylactic or therapeutic treatments of dogs in most of the housing estates in Nigeria. This could undoubtedly minimize the risk of contracting zoonotic infections.

Recently there is a resurgence of interest in community based mass de-worming programmes in contemporary Nigerian health services delivery system. It is plausible that the expected benefits of such program will spill over to zoonotic helminthiaisis. Such benefits could also be potentiated of complementary progammes for mass de-worming of dogs in communities where the dog ownership is rampant and open defecation practice is introduced. As it is, it should be made compulsory for people in this area not to own dogs without adequate veterinary services by veterinary doctors. This would be useful for regular routine check-ups for these dogs including de-worming of these dogs for healthier animals.

The authors are very grateful to Professor, M.O.E, Iwuala of the department of Biological Sciences, Federal University of Technology Owerri for his comments on the initial draft of this manuscripts.