A Survey of Ectoparasites, Cestodes and Management of Free-range Indigenous Chickens in Rural Zimbabwe

INTRODUCTION The importance of rural poultry in national economies of developing countries and its role in improving the nutritional status and incomes of many small-scale farmers and landless communities has long been recognised 3,8,12. Lack of measurable indicators of its contribution to macroeconomic indices such as gross domestic product results in rural poultry not being rated highly in the mainstream of national economies 7. In Africa, rural chickens are more widely distributed than other livestock species. Surveys in many African countries have reported that the main function of rural chickens from the farmer 's perspective is to provide meat and eggs for home consumption 13,24. The development of poultry health programmes requires reliable information on the epidemiology of diseases, which is lacking in village chicken pro


INTRODUCTION
The importance of rural poultry in national economies of developing countries and its role in improving the nutritional status and incomes of many small-scale farmers and landless communities has long been recognised 3,8,12 .Lack of measurable indicators of its contribution to macroeconomic indices such as gross domestic product results in rural poultry not being rated highly in the mainstream of national economies 7 .
In Africa, rural chickens are more widely distributed than other livestock species.Surveys in many African countries have reported that the main function of rural chickens from the farmer 's perspective is to provide meat and eggs for home consumption 13,24 .
The development of poultry health programmes requires reliable information on the epidemiology of diseases, which is lacking in village chicken pro-duction systems 17 .Some limited work has been published on the ectoparasite and gastrointestinal helminth fauna of scavenging chickens in Zimbabwe 2,14,18 and studies in East Africa 15,20,22 have shown high parasite burdens.
It is essential to identify the parasites commonly occurring in backyard or freerange poultry in rural Zimbabwe in order to plan strategies for improvement of production.The aim of this study was to provide information on husbandry aspects of free-range chickens in selected rural districts of Zimbabwe and document the species of ectoparasites and cestodes affecting them.

Study area
The study was conducted in 8 districts of Zimbabwe, namely Chikomba, Goromonzi, Mazowe and Zvimba from the highveld and Zvishavane and Mberengwa from the lowveld (Fig. 1), and Chiweshe (highveld) and Chivhu (lowveld) not shown in Fig. 1.The highveld covers most of the northern half of Zimbabwe and is 1000-1500 m above sea level.The temperature ranges from 25-30 °C during the rainy season and 15-20 °C during the dry season, and mean annual rainfall ranges between 800 and 1200 mm.The lowveld covers most of the southeastern half of the country and is 900 m above sea level.The area is hot throughout the year with temperatures ranging from 23-24 °C.The mean annual rainfall is between 400 and 650 mm.

Study animals
A minimum number of 25 free-range chickens were randomly sampled from different households in each of the 6 districts shown in Table 1.The birds were inclusive of both young and adult of an indigenous breed common in Zimbabwe and had no history of treatment against ecto-and endoparasites using commercial remedies.The minimum age of chickens sampled was 6 weeks.

Recovery and identification of ectoparasites
Hosts were examined under good illumination to locate the ectoparasites on the head, feet and among feathers of the different parts of the body.The legs and featherless areas of the body with any seborrhea or crusts were scraped for microscopic examination.The skin scrapings were processed according to a method already described 19 .After isolation from the host the lice and mites were dehydrated in 80, 90 and 100 % methanol before clearing in xylene and mounting on a slide prior to microscopic examination and identification.Ticks were preserved in 70 % alcohol before identification.
All identifications to generic and species level was as recommended 21,25 based on the morphological characteristics and anatomical location of the parasite on the host.

Recovery and identification of cestodes
The digestive tract of each chicken was separated into small intestines and large intestines including caeca.Each segment was opened into a separate container.The mucosae of the separated parts were scraped off using a glass slide and thoroughly washed in tap water over a sieve with 200 µm apertures.Cestodes were recovered from the washings using a stereoscopic microscope and preserved in 70 % alcohol for identification.Cestodes were processed and identified following described methods and identification keys 9,11,21 .

Information on management of rural chickens
Structured interviews were carried out by the authors in a number of households in the Chiweshe and Goromonzi (Highveld) and Chivhu, Zvishavane and Mberengwa (lowveld) districts (Table 3) and were conducted with the persons directly responsible for the management of the chickens.Information regarding the principal sources of the chickens, purpose of keeping chickens, management system, type of housing, type of feed and the frequency of feeding was recorded.

Data processing
Prevalence of infection (%) was calculated for each ectoparasite and cestode species per district as follows:

Number of infected chickens Total number of chickens examined
× 100 Frequencies of husbandry parameters were computed using Excel.

RESULTS
A total of 270 birds from 6 districts was examined and 11 species of ectoparasites (Table 1) and 9 species of cestodes (Table 2) were recovered.
The highest numbers of cestode species were recorded in the highveld districts of Goromonzi (7) followed by Mazowe (6)  and Zvimba (5).Chikomba district had the least, with only 3 cestode species recorded.In the lowveld, 4 species were recorded in Zvishavane district and 2 in Mberengwa.Raillietina (Pironnella) sp. and Cotugnia digonopora are new records for Zimbabwe.The most frequently encountered cestode species across the districts were R. tetragona and R. echinobothrida, which were recorded in all districts, and the least frequent was R. (Pironnella), which was recorded only in 1 chicken.
The main purpose of keeping chickens in all districts was for meat and the majority of households raised their own chickens, with a few households buying from commercial breeders (Table 3).The chickens were mainly kept extensively in all districts and the common housing was of a rustic type.The households who practised feeding of chickens either fed them in the morning or towards evening and the type of feed was mainly home-mixed grains.

DISCUSSION
Results from this survey show that ectoparasites and cestodes are common in rural free-range chickens in Zimbabwe, and climatic conditions influence the abundance and diversity of these groups of parasites, with the highveld region (high rainfall) having a higher prevalence and diversity than the lowveld region (low rainfall).
Eight species of ectoparasites have been reported to occur in the Goromonzi district  1,18 .Of the 3 species mentioned above, M. stramineus has been reported to reduce weight gain and egg production in free-range chickens 4 , cause irritation and loss of plumage 5 .Argas sp., although found in lower frequency and limited to only 2 districts, has been implicated as a cause of high mortalities due to the blood-sucking habit of the parasite and may also act as a vector of Aegyptianella sp. and Borrelia sp., 6 and the larvae have been reported to cause paralysis in chickens 16 .The nymphs and adults of the tick are temporary obligate parasites and only visit birds when feeding, indicating that the prevalence recorded in this study could have been higher if the parasite was searched for where the birds were housed at night.The prevalence of cestode species in free-range chickens in Zimbabwe has been recorded in the Goromonzi district 18 and in the Harare metropolitan area 10 .Only 1 cestode species, R. cesticillus, was recorded at a very low prevalence 10 .Six cestode species were recorded 18 with the following prevalences; R. tetragona (94 %), R. echinobothrida (66 %), Hymenolepis sp (62 %) with A. cuneata, Skrjabinia cesticillus and Choanotaenia infundibulum having a prevalence of ≤60 %.The previously recorded prevalences of the different ces-tode species are comparable with the findings of this study.However, the authors did not isolate Cotugnia digonopora, Davainea proglottina and Raillietina (Pironnella) spp., which were present in 3 districts in this study.The difference in the coverage of study areas might have strongly influenced the differences in the diversity of species recorded, since the former study 18 covered only 1 district compared with 6 districts in this study.
Respondents from all districts surveyed in this study mentioned a variety of reasons for keeping chickens, with the majority of households keeping them for meat.This is partly in agreement with studies reported from Tanzania, 25 where meat and eggs were predominant.Although all respondents provided housing for their chickens, the majority provided a rustic type of housing and this is   attributed to lack of funds and resources to built adequate housing 23 .Result also show that supplementary feeding of the chickens was not routinely practised and hence scavenging was the major feeding system.The high prevalence of cestodes recorded in this study can be attributed to the scavenging diet that includes a variety of species of arthropods and molluscs that act as intermediate hosts to these parasites 17 .

Table 2 :
Number and prevalence (% in brackets) of

Table 3 : Summary of information collected on the management of free-range chickens during the survey.
n = Number of owners interviewed.