Public health and economic importance of livestock diseases with the emphasis on zoonoses including brucellosis, Q-fever and Rift Valley Fever in Somali region, Ethiopia

Background
Horn of Africa (HoA) is the home of the largest pastoralist communities in the world. The pastoralist communities live in arid and semi-arid lands of the region characterized by harsh climatic conditions. The reality of climate change is becoming more visible in recent years. The pastoralist communities are the most vulnerable victims to climatic hazards more than any society on earth. Moreover, diseases, malnutrition, conflicts and poor health services exacerbated the threats to the livelihood of these communities.
Aims
The aim of this PhD thesis is to establish public health and economic importance of livestock diseases with the emphasis on zoonoses including brucellosis, Q-fever and rift valley fever in humans and livestock in Somali region of Ethiopia. Specifically we aimed:
• To estimate seroprevalence of brucellosis, Q-fever and rift valley fever in humans and livestock
• To identify the risk factors for transmission of zoonotic diseases between humans and livestock
 To assess community awareness on zoonotic diseases
 To investigate the risky practices among pastoral and agro-pastoral communities
 To evaluate livestock trade in Somali region
 To identify livestock diseases including zoonoses that can hinder livestock trade
 To map livestock trade routes and identify the highest concentrated livestock markets
Methods
This PhD thesis is composed of three major components. First, we estimated the seroprevalence of brucellosis, Q-fever and rift valley fever in humans and livestock in Adadle woreda of Somali region. Secondly, we assessed community awareness about zoonotic diseases, their risky practices that favor zoonotic diseases transmission and the most reported livestock diseases in the area. Finally, we studied livestock trade and its associated livestock diseases.
A multi-stage cross sectional cluster study to estimate the seroprevalence of brucellosis, Q-fever and RVF in humans and livestock. Logistic regression was used to estimate the apparent seroprevalence of humans and livestock. We also used uni and multivariable analysis to identify the predictors for seropositivity. Generalized Estimating Equation (GEE) model was used to account the potential correlation within herds. Finally, Pearson’s correlation coefficient was calculated to check the correlation between humans and livestock prevalence.
Both quantitative and qualitative methods were used to assess community awareness on zoonoses and livestock trade in the study area.
Principal findings
The individual seropositivity of Q-fever by species was 9.6% (95% CI 5.9-15.1) in cattle, 55.7% (95% CI 46.0-65.0) in camels, 48.8% (95% CI 42.5-55.0) in goats, 27.0%(95% CI 20.4-34.0) in humans and 28.9% (95% CI 25.0-33.2) in sheep. In humans, seropositivity of Q-fever in males was 28.9% vs 24.2% in females (OR= 1.3; 95% CI 0.6-2.5). Camel seropositivity of Q-fever was significantly associated with age (OR= 8.1; 95% CI 2.8-23.7). The individual apparent seroprevalence of RVF was 13.2% (95% CI 8.7-18.8) in humans, 17.9 % (95% CI 11.0-27.8) in cattle, 42.6% (95% CI 34.8-50.7) in camels, 6.3% (95% CI 3.3-11.6) in goats and 7.4% (95% CI 4.7-11.5) in sheep. Camels had the highest seropositivity of both Q-fever and RVF. The camel seropositivity was 55.7% (95% CI 46.0-65.0) and 42.6% (95% CI 34.8-50.7) for Q-fever and RVF respectively. Generally, there was only a weak correlation between human and livestock seropositivity for both Q-fever and RVF. Only cattle and camels were found seropositive for brucellosis by iELISA. The individual seroprevalence of brucellosis was 2.8(0.9-6.4) in humans, 1.5% (95% CI 0.2-5.2) in cattle and 0.6% (95% CI 0.0-3.2) in camels.
Awareness level on zoonoses in agropastoralists was relatively higher than in pastoralists. Only family size was statistically significant (p<0.05) in association with awareness level in multivariable analysis. About three-quarters of respondents did not know about “zoonoses”. The diseases/syndromes reported as zoonoses were anthrax, cough, hemorrhagic septicemia, foot and mouth disease and tuberculosis. Raw milk consumption, animal birth assistance without protective material, and throwing aborted fetus in the field were among risky practices reported. Poor veterinary services, lack of livestock market, insufficient animal health professions and animal diseases were reported as problems in the area. Some perceptions were recorded which states that knowing about zoonoses as bad idea since people will get afraid from their livestock if they knew about zoonoses.
Small ruminant species dominated the livestock trade. Most of the traders sold their animals to near local markets. Gode, Jigjiga and Harteshek were the dominant livestock markets to sell respectively. High input trade costs were reported like transportation, broker, tax, treatment, feed, labor and personnel costs. The main factors hindering livestock trade were drought, disease, security, conflicts, hard currency exchange rate fluctuation and poor market. The reported trade problems exacerbate if drought and/ diseases occur. Trypanosomiasis, anthrax, sheep and goat pox, helminthiasis, foot and mouth disease (FMD), tick infestation, contagious caprine pleuropneumonia, diarrhea, nasal discharge and Nairobi sheep disease were the most common outbreaks reported to hinder livestock trade.
Livestock demand increased during Arafa, Mowlid, Eid-Al Adha religious ceremonies, and during the rainy season. Gode was the main livestock market in the area and received high numbers of animals from various parts of the surrounding zones as well as neighboring Somalia. The major livestock trade destinations reported were Somaliland, Puntland, Saudi Arabia, United Arab Emirates, Oman, Qatar, Egypt and Yemen (no market currently due to war). The customs and revenue authority reported that livestock export increased during strong control of contraband activities and vice-versa. Informal livestock trade share was high in the current livestock trade. The major livestock diseases targeted by the quarantine office were; FMD, brucellosis, sheep and goat pox, camel pox, ovine and bovine pasteurollosis, and Peste des petits ruminants (PPR). Export animals were vaccinated according to the type of vaccines requested by the importing countries.
Conclusions
This study showed the exposure of RVF in humans and livestock for the first time in the country. The low awareness level on zoonoses, risky practices and misconception about zoonoses might increase the risk of zoonotic infections transmission between humans and animals in the area. Thus, community awareness and education about zoonoses is essential. Further research on socio-culture perspective on zoonoses awareness and risky practices is required. Collaboration between public and animal health sectors for further investigation on these zoonoses using the One Health concept is indispensable.
Despite the existing livestock trade challenges, livestock trade supported many poor pastoralist communities. The dominant livestock markets could be used as critical points for zoonotic disease control interventions in the future. Knowledge on livestock trade and its associated diseases, routes and systems in place can contribute to designing appropriate policies and strategies that could improve the economy, health and well-being of pastoralist communities in Somali region.