Risk factors and socioeconomic effects associated with spread of peste des petits ruminants (PPR) in Turkana county, Kenya
Abstract
Livestock keeping is the main source of livelihood for most pastoral households found
in arid and semi arid lands (ASAL) of Kenya which are characterized by prevalence of
diseases, extreme climatic features of drought, flooding, low investments, fragile
ecosystems and high poverty levels as challenges to the pastoral livestock sector growth.
Small stock keeping is one of the major livelihood activities for the pastoral
communities which contribute heavily to pastoral household subsistence and market
income. A major constraint to small stock keeping is emerging viral diseases including
PPR that is a relatively new, highly contagious and often fatal disease of sheep and goats
that has caused devastating losses in Kenya since it was first officially reported in 2007
in the Turkana County.
Peste des petit ruminants has since spread to almost all ASAL pastoral counties in
Kenya. Efforts to control the disease in Kenya have been limited due to lack of
epidemiological information while the risk factors and socio-economic effects
associated with the spread of the disease in Turkana District are not fully known. As
such it has not been clear how effective the control activities implemented had been in
stemming the spread of the disease in Kenya.
The general objective of the study thus was to assess the risk factors and socio-economic
effects associated with the spread of PPR in Turkana County, while the specific
Determine the disease socio economic impact and (4) Document and evaluate the
control strategies of the disease in Turkana County of Kenya.
The risk factors associated with the spread of PPR in Turkana County were identified
using participatory epidemiology (PE) methodologies. The data on community
participatory appraisal of PPR disease was validated with field pathological samples that
were collected and the PPR virus RNA analyzed with qRT-PCR both in fresh frozen
samples and formalin fixed tissues. Histology samples were also examined for
pathological lesions associated with PPR. Further participatory risk assessment
questionnaires were used to determine community perception of PPR on the risk factors.
The level of herd immunity was determined using serological methods namely cELISA
tests to analyze in 969 serum samples (431 from sheep and 538 from goats) collected in
six divisions of Turkana county that formed the study area. The socio economic impact
of PPR in Turkana County was determined using data derived from PE methodologies,
key informants interviews and secondary data. The current control strategies on PPR in
Turkana Kenya were determined using participatory epidemiology methodologies and
were subsequently documented. A stochastic PPR compartmental model comprising
maternal antibody, susceptible, exposed, infectious and recovered was developed based
on field parameters; it was then used to evaluate the appropriateness of vaccination
Results of PE exercises showed that the Turkana community was in agreement that PPR
in sheep was associated with migration (p<0.001), herd mixing (p<0.001), raids
(p<0.001), and dry season (p<0.01) while in goats PPR was associated with migration
(p<0.001), herd mixing(p<0.001), raids (p<0.001), mountain pastures (p<0.001) and dry
season (p<0.001) . However the risk factors significantly associated with the spread of
PPR in Turkana County were sharing of water points with odds ratio of 2.022 (p<0.001)
particularly during wet season of 2009. Sick nursing mothers were also identified as risk
factor during the wet season of 2010 with odds ratio of 1.621 (p<0.049). In a subsequent
sero-epidemiological study species was significantly associated with presence of PPR
antibodies in a mixed herd of sheep and goats and thus considered risk factors where
goat had Odds ratio= 1.644; (p<0.001). Unvaccinated sheep had odds ratio of 4.24
(p<0.000) compared to the vaccinated sheep while adult goats had odds ratio of 2.381
(p<0.003) in relation to kids for association with presence of PPR antibodies.
The level of herd immunity within the flocks in Turkana was found to be 39.6% in goats
which was significantly (p<0.001) higher than that of sheep at 31.6%. In both species,
middle aged group between 6 months and 24 months were found to have low seropositivity
of between 14.2% and 18.2% rendering this group vulnerable during PPR
outbreak. The sero-epidemiological survey established that high demographic changes in
Apart from drought, livestock diseases were the second most important factor that
disrupt livestock livelihood with PPR being ranked as the disease with highest
destructive impact on the small stock benefits to the Turkana community. The socio
economic impact of PPR was found to be enormous in that it threatens to destroy sheep
and goats that constitute the largest herd of livestock reared; their herd composition
ranging between 42% and 64.4% of the total animal kept across the wealth groups. Lose
of small stock would in essence destroy a source of animal food products which
constitute 29.4% of all the food consumed by a Turkana household and is mainly
consumed by the youthful workforce of morans and girl herders in the age group 13 to
18. The study established that the direct economic losses due to PPR in Turkana County
alone for the year 2010 were in the tune of Kenya Shillings 11.1 billion.
The current control strategies on PPR in Turkana County, Kenya have been found to be
mainly local methods of using herbs as well as reducing contact between sick herds and
healthy herds. Local methods that reduced animal contacts such as running away from
sick herds and local sanctions such as restricted movement or/and access to public water
points and pastures were consistent with scientific control method of creating sanitary
belts. Vaccination was perceived to be among the most effective control method but was
not easily accessed and the community had little knowledge about it; thus was ranked
lowly among other control methods.
Publisher
University of Nairobi
Description
PhD