Helminth parasites in the intestinal tract of indigenous poultry in parts of Kenya

INTRODUCTION Indigenous poultry, which account for about 70 % of the Kenyan poultry population, are kept by a majority of the rural population under the free-range system of production. Indigenous poultry are a major source of protein and income to the population as they are hardier than the exotic faster-growing and more productive breeds of poultry. That helminthiasis, though not clinically manifested, contributes to production losses in the poultry industry in developing countries is becoming more apparent. Several studies have been carried out on free-ranging poultry and the prevalence of gastrointestinal parasites in the region. A study on rural, scavenging chicken from Morogoro, Tanzania found that all of the 600 chickens examined were infected with 1 or several species of helminths with an average number of helminths per bird of 4.8 ± 1.7 during the wet seasons and 5.1 ± 1.8 during the dry season. Other studies showed infection prevalences of 88 % for roundworms in Leku, southern Ethiopia, and 93.5 % for mixed infections from Dschang market in western Cameroon, respectively. The type of management system adopted greatly influences the parasitic load of poultry. It has been shown that chickens reared under the cage system gave negative results for helminth parasites whereas free-ranging chickens had the highest helminth infection rate. Most of the helminth parasites were nematodes. The present study was undertaken to establish the prevalence of helminthiasis in free-ranging indigenous poultry as it contributes to poor poultry productivity, which affects the small scale farmer. The study was to serve as a database on the most common helminths in indigenous poultry. This is important in controlling the prevalence of helminthiasis.


INTRODUCTION
Indigenous poultry, which account for about 70 % of the Kenyan poultry population, are kept by a majority of the rural population under the free-range system of production.Indigenous poultry are a major source of protein and income to the population as they are hardier than the exotic faster-growing and more productive breeds of poultry.That helminthiasis, though not clinically manifested, contributes to production losses in the poultry industry in developing countries is becoming more apparent 2 .Several studies have been carried out on free-ranging poultry and the prevalence of gastrointestinal parasites in the region.A study on rural, scavenging chicken from Morogoro, Tanzania 6 found that all of the 600 chickens examined were infected with 1 or several species of helminths with an average number of helminths per bird of 4.8 ± 1.7 during the wet seasons and 5.1 ± 1.8 during the dry season.Other studies 3,5 showed infection prevalences of 88 % for roundworms in Leku, southern Ethiopia, and 93.5 % for mixed infections from Dschang market in western Cameroon, respectively.
The type of management system adopted greatly influences the parasitic load of poultry.It has been shown that chickens reared under the cage system gave negative results for helminth parasites whereas free-ranging chickens had the highest helminth infection rate 1 .Most of the helminth parasites were nematodes.
The present study was undertaken to establish the prevalence of helminthiasis in free-ranging indigenous poultry as it contributes to poor poultry productivity, which affects the small scale farmer.The study was to serve as a database on the most common helminths in indigenous poultry.This is important in controlling the prevalence of helminthiasis.

MATERIALS AND METHODS
Intestinal samples of 456 indigenous poultry were collected from Kariokor Market, Nairobi.Poultry from various parts of the country are collected and slaughtered there.The samples were separated into foregut, midgut and hindgut, using ligatures, labelled and preserved in 10 % neutral buffered formalin.The sample sections were later opened using scissors and their contents washed into Petri dishes using normal saline.The worms were stored in bottles, fixed in 70 % ethanol and then stored in 10 % formalin before identification.The worms were identified using dichotomous keys 7,8 .Microscopic examination of faeces for helminth eggs was done at ×40-60 magnification after making a direct smear of the faeces or after filtering the faeces in normal saline through a cheese cloth and centrifuging the contents 4 .

RESULTS
Out of a total of 456 specimens observed in the study, 414 were found to be positive whereas 42 were negative for helminthiasis, giving a prevalence rate of 90.78 %.The specimens used in the study came from chickens derived from various towns in Kenya, including Nairobi, Machakos, Kitui, Makueni, Nyahururu and Bomet.Their infection rates are shown in Fig. 1 Most of the helminths were found in the mid-and hindguts with the exception of C. dignopora and T. tenius which were present only in the mid-and hindguts, respectively, and S. trachea which was the only helminth found in the foregut.The latter usually inhabits the respiratory tract.

DISCUSSION
The method used in the present study to quantify the level of helminthiasis is reliable as helminths were observed di-rectly whereas many cases of helminthiasis go unnoticed since clinical symptoms are often undetected.Diagnosis of worm infections by examination of fresh droppings for presence of eggs or segments is also unreliable even in some cases of heavy infection.Although the present study only covers a small area of Kenya where indigenous poultry occur, it does give an indication of the level of helminthiasis in several parts of the country.In Nairobi, Machakos and Nyahururu, the 100 % positive cases could be attributed to the small number of specimens examined (fewer than 20 from each town), which made it less likely that negative cases would be found.By contrast, from Makueni (91.46 % prevalence), 150 specimens and from Bomet (86.59 % prevalence), 116 specimens were examined.Generally, a high percentage of helminthiasis was observed in the present study.This may pose a major problem to the small scale poultry farmers by lowering productivity in the industry.The helminths compete for nutrients with the host and also cause inflammation and lesions in the intestinal tract that interfere with digestion and assimilation of nutrients by the host.
In the absence of control of the parasites and treatment of infected birds, a high helminth load is to be expected in freeranging poultry as the intermediate hosts of the helminths are normally ingested by the poultry.For example, the larval form of Railletinia sp. is found in various intermediate hosts such as ground and dung beetles as well as ants, and the larval stage of H. gallinarum is found in earthworms.Nematodes were the most common helminths.Seven species of nematodes were identified whereas only 2 species of cestodes were seen.Trematodes were not observed in the study as snails and fish serve as intermediate hosts.Poultry are found in the homestead and rarely have access to aquatic conditions, which are habitats of these intermediate hosts.
A control measure that can greatly reduce the helminth load in poultry is one that interferes with the life cycle of the parasite.The intermediate host should not have access to the faeces of poultry since free-ranging poultry will eventually feed on potential intermediate hosts.
Although the disposal of poultry droppings is unquestionably the most important preventive measure towards the control of helminth infestation because faeces is the source by which intermediate hosts become infected, this is not applicable in a rural setting.Such drop-pings can be spread out thinly on land out of reach of poultry or in places rarely frequented by poultry.The dehydrating effect of the sun and wind on the droppings will quickly destroy the parasitic material in the droppings and the droppings will also enrich the land as a fertiliser.Such a practice can be accompanied by rotation of the birds from one area to another in order to reduce parasitism among birds.