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

INTRODUCTION In order to meet the ever-increasing demand for animal protein in Nigeria and at the same time generate additional income, most families in urban areas now engage in livestock farming. The economic benefits of urban livestock farming notwithstanding, it is important to note that the practice of breeding cows, sheep, goats and pigs in and around human dwellings has increased human–animal contact, with serious zoonotic implications. Nwoke observed with distress that this association has now made it possible for parasites and pathogens naturally harboured by these livestock (and hitherto restricted to animals) to commonly infect people. Increase in the prevalence of faeco-oral zoonotic diseases in South America and Africa have for long been a subject of investigation. Considering environmental deterioration accompanying increased urban livestock farming and burgeoning urban population in Nigeria, increased incidence of zoonotic helminthiasis is expected. The incidence and prevalence of zoonotic infections is on the increase especially in developing countries. Among helminth zoonoses affecting humans in Africa are those with domestic and/or peridomestic cycles and reservoirs in pigs, dogs, goats and cattle. Serious contamination of the urban environment with animal faeces have been reported in Chile, Abidjan, Malaysia and Nigeria. Though the entire urban population is at risk of contracting zoonotic infections either through direct contact with animals or indirectly through ingesting food, water, vegetables or soil contaminated with animal faeces, animal breeders, occupants of the residences where animals are raised and abattoir personnel are most at risk. Zoonotic helminth pathogens that may be contracted from dogs, goats, sheep, pigs and cattle in Nigeria include Toxocara species, Echinococcus species and Taenia species. In addition, these animals also naturally harbour ectoparasites such as ticks, fleas, mites and lice. The clinical features resulting from these infestations and the pathological consequences of the diseases transmitted by these parasites in domestic animals have been widely documented in Nigeria and elsewhere. The economic losses resulting from ectoparasitism of livestock runs into billions of US dollars worldwide. Ectoparasites such as ticks, lice, fleas and mites may parasitise humans and have been incriminated in the mechanical transmission of pathogens while sucking human blood and in causing direct damage to the skin by vesication, irritation, invasion of tissues and stimulation of allergic responses. Incidence of the tapeworm (Dipylidium caninum) in children who had accidentally swallowed dog fleas (Ctenocephalides canis) and the infestation of 41.5 % of school children in Badagry near Lagos with Tunga penetrans, a flea that can cause serious inflammation of the feet, leading to ulceration and fibrosis, are all public health consequences of the close association with livestock. Human infestations resulting from mites (Sarcoptes scabiei) and ticks from dogs, cats, goats and cattle occasionally occur as a result of frequent close contact with these animals. Human babesiosis, tick paralysis and intensive pruritic dermatitis sometimes progressing to papular eruption have been reported amongst livestock handlers in parts of Africa and Australia. Having observed the large concentration of roaming livestock scavenging for food and littering streets of Makurdi with their faeces, this study was designed to investigate the environmental and public health implications of urban livestock rearing especially as it relates to zoonotic helminthiasis. The objectives were to collect and identify ectoparasitic fauna of dogs, goats, sheep, pigs and cattle being


INTRODUCTION
In order to meet the ever-increasing demand for animal protein in Nigeria and at the same time generate additional income, most families in urban areas now engage in livestock farming.The economic benefits of urban livestock farming notwithstanding, it is important to note that the practice of breeding cows, sheep, goats and pigs in and around human dwellings has increased human-animal contact, with serious zoonotic implications.Nwoke observed with distress that this association has now made it possible for parasites and pathogens naturally harboured by these livestock (and hitherto restricted to animals) to commonly infect people 21,22 .Increase in the prevalence of faeco-oral zoonotic diseases in South America and Africa have for long been a subject of investigation 24,28 .Considering environmental deterioration accompanying increased urban livestock farming and burgeoning urban population in Nigeria, increased incidence of zoonotic helminthiasis is expected.
The incidence and prevalence of zoonotic infections is on the increase especially in developing countries 17 .Among helminth zoonoses affecting humans in Africa are those with domestic and/or peridomestic cycles and reservoirs in pigs, dogs, goats and cattle.Serious contamination of the urban environment with animal faeces have been reported in Chile, Abidjan, Malaysia and Nigeria 2,17,28,29 .Though the entire urban population is at risk of contracting zoonotic infections either through direct contact with animals or indirectly through ingesting food, water, vegetables or soil contaminated with animal faeces, animal breeders, occupants of the residences where animals are raised and abattoir personnel are most at risk 7,21,24,33 .
Zoonotic helminth pathogens that may be contracted from dogs, goats, sheep, pigs and cattle in Nigeria include Toxocara species, Echinococcus species and Taenia species 9 .In addition, these animals also naturally harbour ectoparasites such as ticks, fleas, mites and lice.The clinical features resulting from these infestations and the pathological consequences of the diseases transmitted by these parasites in domestic animals have been widely documented in Nigeria and elsewhere 4,15,26,31,34 .The economic losses resulting from ectoparasitism of livestock runs into billions of US dollars worldwide 18,5 .
Ectoparasites such as ticks, lice, fleas and mites may parasitise humans and have been incriminated in the mechanical transmission of pathogens while sucking human blood and in causing direct damage to the skin by vesication, irritation, invasion of tissues and stimulation of allergic responses 1,32 .Incidence of the tapeworm (Dipylidium caninum) in children who had accidentally swallowed dog fleas (Ctenocephalides canis) 20 and the infestation of 41.5 % of school children in Badagry near Lagos with Tunga penetrans, a flea that can cause serious inflammation of the feet, leading to ulceration and fibrosis, are all public health consequences of the close association with livestock 1 .Human infestations resulting from mites (Sarcoptes scabiei) and ticks from dogs, cats, goats and cattle occasionally occur as a result of frequent close contact with these animals.Human babesiosis, tick paralysis and intensive pruritic dermatitis sometimes progressing to papular eruption have been reported amongst livestock handlers in parts of Africa and Australia 4,22,28 .
Having observed the large concentration of roaming livestock scavenging for food and littering streets of Makurdi with their faeces, this study was designed to investigate the environmental and public health implications of urban livestock rearing especially as it relates to zoonotic helminthiasis.The objectives were to collect and identify ectoparasitic fauna of dogs, goats, sheep, pigs and cattle being raised by urban farmers and to parasitologically analyse faecal and soil samples collected from within residential premises for ova of animal helminths.

Study area
Makurdi, the capital of Benue State, Nigeria, is fast becoming a metropolitan centre with attendant health, social, housing and environmental problems.It lies between latitude 07°15'-07°45'N and longitude 08°15-08°40'E.The town lies in the guinea savanna vegetative belt and on the bank of the 2nd-largest river in Nigeria, River Benue.The river divides the town into north and south banks and the town covers an area of 16 km 2 (Fig. 1).The river constitutes the main source of water supply for the inhabitants of the town.The sudden influx of commercial and developmental activities that resulted from rapid urbanisation has side-lined many indigenous people and urban migrants, consequently, the populations of poorer residential areas such as Wadata, Wurukum and North Bank are beginning to swell.These 3 high-density residential areas were selected for sample collection.

Wadata
Wadata constitutes a reasonable population of the town, located along the bank of the river towards the western end of the town.The area is densely populated with inadequate water supply, sanitary and waste management.Drainages are open and blocked by piles of rubbish.In addition to residential houses, there is a market, a prison yard, an abattoir, a rice mill, and thriving burnt-brick production along the bank of the river (Fig. 1).The inhabitants of this area are largely Hausas and Jukuns who are active fishermen.The majority of the Hausa residents combine livestock keeping and other forms of petty trade.It is therefore very common for many households to keep goats, sheep and cattle on residential premises and to practice free-range systems of husbandry.

Wurukum
This is another residential settlement within the metropolis; the actual study was conducted in a portion called Angwan-Jukun.It is known for its unhygienic conditions, overcrowding, poor state of housing and lack of clean water.Heaps of refuse block access to the road while municipal waste disposal facilities are non-existent.The Jukun ethnic group used to be the predominant residents but this is rapidly changing owing to the in-flux of other ethnic groups as a result of lower rents.Landmark facilities include a rice-mill, an abattoir and vegetable farms along the river bank.The predominant animals kept by the residents inthis area are goats and pigs which are reared under a free-range system.Their faeces are usually used as manure for the vegetable farms.

North Bank
The north bank area is located across the river towards the north; the actual study site is the area called Angwan-Sariki (Fig. 1).The area is densely populated and there are prominent gully erosion sites and these gullies serve as refuse dumps.The residents in this area are also engaged in free-range rearing of cattle, sheep and goats, trading and other small-scale businesses.The majority of the residents lack clean water and depend on the river for water.Sanitary conditions are poor and most drainages are blocked with piles of rubbish.

Parasitological examination of soil for eggs of helminths
The test tube flotation method was used 5,19 .Five grams of the soil sample were mixed thoroughly with distilled water.The suspension was strained through a net mesh to remove coarse particles.The filtrate was centrifuged for 3 minutes and the supernatant decanted.The resultant sediment was further broken-up by shaking and tapping the tube.The sediment was mixed with zinc sulphate solution (specific gravity of 1.2).This was added up to the brim of the test tube until a positive meniscus formed and allowed to stand for a 5 minutes with a cover slip to collect any floating eggs.The cover slip was then removed and examined microscopically.

Parasitological examination of faecal samples
Faecal samples were collected from the ground using stainless steel teaspoons to put the material into specimen bottles containing normal saline solution (0.85 % NaCl).Each sample solution was washed and filtered through fine grades of mesh sieves sized 90, 60 and 30 into sieve tubes to prevent loss of adult parasites and ova.The filtered solution was poured into centrifuge tubes and centrifuged for 5 minutes at 1500 rpm using an electric centrifuge.The supernatant was then poured off leaving behind the sediments, after which 1 or 2 drops of the sediment were placed on a glass slide and viewed under a light microscope for identification of ova, larvae and adults helminth parasites.Parasites were identified using the keys provided 26 .The direct wet mount technique was also used for fresh specimens, and isolation of visible worms 32,27 .

Sampling methods for ectoparasites
Ectoparasites were collected from dogs, goats, sheep, pigs and cattle with the assistance of members of the household.Ticks were collected using the handpicking and hair-brushing methods 16 .The entire animal's body was inspected and brushed with special attention paid to the ears, the area around the eyes, the axillae and the groin as recommended 26 .Fleas, mites and lice were collected by combing and brushing the animal's entire body surface onto a white cloth dipped in formalin to prevent fleas from jumping and mites and lice from creeping away 32 .

Preservation and identification
Ectoparasites collected were transferred to the laboratory in clearly labeled specimen bottles containing 70 % alcohol.The sex and type of animal from which the parasites were collected was noted and recorded on each specimen bottle.Ticks, lice, mites and fleas were identified using keys and illustrations 26,32,28 .

RESULTS
Of the 150 soil samples collected from residential premises where livestock farming is practiced, 55(36.7 %) were positive for 1 or more parasite ova.Ascaris species were most frequently encountered, and comprised A. suum (22.8 %), T. vitulorum (13.2 %), Toxocara canis (19.8 %) and T. cati (9.5 %) (Table 1).Soil samples collected from various homes revealed high levels of contamination with animal faeces.There was, however, no significant difference in the prevalence of eggs in the soil and level of contamination in the 3 areas sampled (χ 2 = 0.046, df = 2, P > 0.05).More premises in Wurukum, however, recorded a higher percentage (44 %) of homes with ova of parasites than Wadata and North Bank.Compounds visited had no special provision for the disposal of animal faeces and animal faeces were treated as household refuse.
A total of 221 domestic animals were examined for ectoparasite infestation (43 cattle, 45 sheep, 45 goats, 44 pigs and 44 dogs) and 1908 ectoparasites were recovered.Ticks accounted for 32.80 % of all ectoparasites while lice, fleas and mites accounted for 22.43 %, 22.06 % and 22.69 %, respectively (Table 4).The highest infestation rates were seen in cattle and pigs.While 75 % of the cattle examined had ticks, 88.63 % of the pigs were infested with fleas (Tunga species) (Table 3).There was no significant difference in the rates of infestation between male and female animals (χ 2 = 0.10, df = 1, P > 0.05).
Amblyomma species were the most dominant ticks encountered (40.10 %) and were recovered from 38.79 % of all animals that were infested with ticks.Linognathus species (43.90 %), Ctenocephalides species (97.38 %) and Sarcoptes species (58.89 %) were the most predominant species of lice, fleas and mites, respectively (Table 4).A comparison of the 3 study sites showed that even though more ectoparasites were encountered in the North Bank area, this difference was not statistically significant (χ 2 = 1.83, df = 4, P > 0.05).The distribution of the ectoparasites in the 3 areas showed no consistent pattern (Fig. 3).Fig. 2: Prevalence of helminth eggs and larvae in faeces of examined animals.

DISCUSSION
The widespread contamination of residential compounds with eggs of animal helminth parasites observed in this study is epidemiologically significant.These findings agree with others reported elsewhere 33,29,14 and in Nigeria 10,8,2 .The presence of potentially pathogenic helminth parasites in the home environment highlights the risk of human infection.The viability of these parasite eggs under different environmental conditions is focal in the transmission of zoonotic diseases.Contamination of residential compounds with eggs and larvae of animal helminth parasites as observed in this study indicates the possibility of transmission of soil-borne zoonotic infections.
Nigeria is currently experiencing an unprecedented rise in urban livestock farming 21,22 .The large concentration of roaming farm animals or those restricted within residential homes reduces hygienic standards and increases the risk of acquiring zoonotic diseases.Epidemiological data on zoonotic diseases in Nigeria scarce but immunological studies in other developing countries reported high numbers of visceral larva migrans cases in children, which was attributed to the tendency of children to swallow soil while playing and soil contaminated with helminth ova and larvae of domestic animals 25 .Apart from the risks resulting from the accidental ingestion of contaminated soil, handling of these animals could also predispose humans to infections.Serological surveys in Djibouti amongst livestock handlers and abattoir personnel concluded that abattoir personnel and livestock breeders carried more zoonotic infections which are transmitted by contact with animals than other population groups 7 .
The heavy infestation of animals cohabiting with humans by ectoparasites of veterinary and medical importance has severe consequences for arthropodborne zoonotic diseases.Species encountered in this study and infestation rates observed agree with findings reported in some parts of Nigeria 15,30,12,16,34 and elsewhere 4,31 .The predominance of ticks, especially species incriminated in the transmission of babesiosis and other livestock diseases, has serious economic consequences for livestock farmers and the industry.Anaemia may also result in heavy infestation, thereby weakening the animals and even killing younger ones.
The ability of these traditional animal ectoparasites to bite humans and suck human blood and sometimes transmit zoonotic diseases is the main concern in this study.Ticks from dogs and other livestock have been reported to occasionally bite humans and transmit Lyme disease, tick paralysis, human babesiosis and relapsing fever in parts of North America, Africa and Australia 32,20,28 though these diseases have never been reported in Nigeria.Mild dermatitis sometimes progressing to papular eruption in humans infested with scabies mites have been documented 6 .Dog and cat fleas on the other hand have been reported to transmit Dipylidium caninum in children who accidentally swallow infected fleas while with pets 28,32 .School children in Badagry near Lagos, Nigeria, were infested with Tunga penetrans, a flea that can cause serious inflammation of the feet, leading to ulceration and fibrosis 1 .They explained the high prevalence of infestation to close association of children with large numbers of pigs (another host) that roam about in the area.
The large concentrations of roaming animals as well as those restricted within residential homes reduces hygienic standards and increase the risk of acquiring arthropod-borne zoonotic infections.Though human infestation with ticks and other ectoparasites is not widespread in Nigeria, the dismantling of the biological barriers between livestock and man has resulted in the emergence and re-emergence of new zoonotic infections 24 .
The usage of residential premises to rear livestock also poses serious challenges to ectoparasite control.Traditionally, ectoparasites are controlled using effective insecticides either by spraying on animals or by dipping the animals in swim pits.Some of the organophosphorus compounds used are toxic to humans and their application within the domestic environment may have serious residual consequences.Some ectoparasite species are capable of living for prolonged periods independent of the host and may also develop resistance to chemicals used for their control.Other obstacles to controlling vector-borne zoonotic infections include: diversity of social, cultural and administrative structures, inadequate education of the population and overcrowding of both animals and humans in an already deteriorating urban environment 17,24 .
Urban livestock farming will no doubt exacerbate the environmental and public health problems being experienced in many urban areas in the developing world.It is a common experience these days to see livestock roaming in and around houses in search of food.While feeding, they defecate indiscriminately, seeding residential and recreational areas with excreta-borne pathogenic organism 14,29,23 .The large concentration of these livestock scavengers in search of food in The benefits of urban livestock farming, especially in meeting the demand for essential animal protein notwithstanding, it is important to note that helminth zoonoses are becoming a major health problem in developing countries with domestic and peridomestic cycles and reservoirs in pigs or cattle 24 .The enforcement of already existing prohibition on stray and roaming animals in urban areas will go a long way to preventing environmental pollution.For the urban livestock farmers, interactive health education, highlighting the zoonotic disease implications of cohabiting with animals will enhance the adoption of more responsible and hygienic animal handling and production.