The Epidemiology and control of East Coast fever and other vector-borne diseases: perceptions of the pastoral communities in Northern Rift Valley Province, Kenya
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Date
2009Author
Kipronoh, Kipruto K
Type
ThesisLanguage
enMetadata
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A participatory epidemiological study was conducted among the Pokot and Tugen
communities in Northern Rift Valley, Kenya, to assess the status of tick-borne infections
and obtain livestock keepers' perceptions of how the diseases impact on livelihoods in
pastoral and agro-pastoral production systems. In addition a serological survey was
carried out to assess antibody prevalence of priority vector-borne diseases namely ECF,
Anaplasmosis and Babesiosis, as perceived by the livestock keepers and serum samples
were collected from 190 animals of all age groups. Only calves over 4 months of age
were sampled to avoid confusion with passively transferred colostral antibodies. Thick
and thin blood smears were prepared from the marginal ear vein of all the animals bled.
Lymph node biopsy smears were also collected from animals suspected to be sick based
on symptoms of disease for microscopic examination. Whole body tick counts were
carried out on cattle selected for sampling and tick samples were collected for
identification and assessment of infection prevalence.
The choice of these communities to participate III the exercise was based on their
economic dependence on livestock, cultural beliefs and practices and the nature of their
ecological setting, typical for pastoral and agro-pastoral production systems. The
objectives of the study were 1) to study the pattern of East Coast fever and the
distribution of the vector tick in pastoral areas of the Northern Rift Valley; 2) to estimate
the incidence and mortality of ECF and other important vector-borne diseases; 3) to
estimate the sero-prevalence of East Coast fever and other vector-borne diseases; and 4)
to assess factors influencing the sero-prevalence of ECF and other vector-borne diseases
and control practices by the pastoral livestock keepers.
The study was conducted in 22 Pokot and 22 Tugen manyattas/villages in different sublocations
that were purposely selected on the basis of accessibility and security. Group
discussions and Key-informant interviews were organised through the local leaders while
others were held without prior arrangement. Some of the data collection methods used
included, proportional piling, seasonal calendars, participatory mapping, disease impact
matrix scoring and focused group discussions alongside key informant interviews. Semi
structured interviews were used for probing and clarification of results from the
exercises. A total of 658 livestock keepers were interviewed in 22 village meetings each
in West Pokot and Baringo districts over a period of two months. Eleven of the villages
werepredominantly pastoral (where 175 livestock keepers were interviewed), while the
remaining 483 livestock keepers were interviewed in 33 villages in agro-pastoral
production system.
The most important livelihood sources were reported to be livestock keeping, crop
farming, small scale business and bee keeping. Households in both communities
depended largely on livestock as the major source of livelihood. The enterprise was
ranked as a priority in both study districts by 95.5 %; 21122 and 90.9%; 20122 of the
groups in West Pokot and Baringo districts respectively. The main species of livestock
kept were cattle, goats, sheep and poultry in order of preference. Donkeys and camels
were ranked fifth and sixth positions in importance respectively. Crop farming was
ranked as the second most important livelihood activity after livestock by both
communities mainly as a supplement of household economy.
All the households in pastoral divisions kept the zebu cattle as their main breed. On the
other hand, 83.9% of the households in agro-pastoral divisions had zebu crossbreds while
the remaining 16.1% kept pure-bred zebu. Grazing was purely on communal pasture in
pastoral divisions whereas in agro-pastoral areas, grazing was mainly in individual land
holdings (85.7% of the respondents) with communal grazing being practiced by only
14.3% of the respondents. In both production systems, water for livestock was mainly
from streams and rivers (for 80.1%. of the herds) with the remaining 19.9% getting water
from other sources including communal boreholes, dams and piped water sources. More
than 85% of the households in both systems practiced tick control with frequencies
varying from weekly regimes to only at the sight of ticks on animals
Major constraints affecting livestock keeping were reportedly livestock diseases, shortage
of feed, lack of water/distant watering points, insecurity, wildlife menace and poor
markets. Livestock diseases were ranked as the main constraint in pastoral areas whereas
shortage of animal feed was considered to be of major importance in agro-pastoral areas.
Vector-borne diseases particularly tick-borne (ECF and heartwater) and trypanosomosis
(transmitted by tsetse flies) were the main examples of diseases noted to seriously limit
livestock production in these areas. East Coast fever was scored as the most important
disease across the study areas based on the results from proportional piling. The disease
was given the highest relative mean score of 42.2 by all the groups in pastoral areas and
47.4 by 92% of the groups in agro-pastoral areas). This was followed by trypanosomosis
with a relative mean score of 23.8 and 25.5 by 80% and 92% of groups in pastoral and
agro-pastoral areas, respectively. Mean Incidence of ECF was higher in calves up to 2
years and was estimated at 37.9% compared to 17.7% and 19.4% for weaners and adults
respectively. Mortality due to ECF was 23% for calves and approximately 10% for both
adults and weaners.
Results from various group discussions demonstrated good agreement among informants
with Kendalls' coefficient of concordance (W) values ranging between 0.43 and 0.60 (p <
0.05 - P < 0.01). In all the groups, impact ofECF was found to be the highest. Ticks were
perceived to be present in high numbers during the wet season and the inter-phase.
Equally, high cattle losses resulting from ECF were reported to occur during the wet
season. This underscored the role seasons, which may be the source of tick infestation
and subsequent disease outbreaks.
The sera-prevalence for Tparva A. marginale and B. bigemina determined by ELISA
were 25.8, 53.2 and 53.7, respectively. The prevalence estimates for A. marginale and
B.bigemina were significantly higher in pastoral than agro-pastoral production systems (p
= 0.002 and 0.001 respectively). They were also significantly different in cattle grazed in
communal pastures and those in private paddocks (p = 0.001). However, no significant
difference was observed for antibody prevalence for T parva between the two grazing
management systems.
There was evidence from the study that herd disease control was mostly in the hands of
livestock keepers and majority (67%) of them carried out animal drug administration on
their own with very few of them seeking expert consultation.
Based on the findings from this study and given the role played by livestock to
livelihoods in these areas, the economic importance of ECF and other TBDs and the
livestock keepers' knowledge of the diseases, there is need for stakeholders in the
livestock industry, to reconsider developing control options that are supportive of the
production systems. This calls for the establishment and/or strengthening of their
collaborative network in an effort to come up with alternative control strategies of ECF
and other VBDs including the option of immunization, Integrated Control of Ticks and
Tick-borne Diseases (lCTTBD) and introducing mobile veterinary clinics with the aim of
developing better ways of delivering the technologies to the marginalised pastoral
communities.
Citation
Master of Science in Veterinary Epidemiology and EconomicsPublisher
University of Nairobi Department of Public Health, Pharmacology and Toxicology