Tick-borne diseases in the Union of the Comoros are a hindrance to livestock development: Circulation and associated risk factors.

Tick-borne diseases (TBD) occur in many temperate countries and are economically important in most tropical and subtropical areas, affecting dairy and beef cattle, as well as small ruminants. Four major tick-borne diseases have been detected in eastern and southern Africa: East Coast fever (ECF) caused by Theileria parva, Theiler 1904, anaplasmosis caused by either Anaplasma marginale, Theiler 1910, Anaplasma centrale, Theiler 1911, or Anaplasma ovis, Bevan 1912, babesiosis caused by Babesia bovis, Babes 1988 and Babesia bigemina, Smith & Kilborne 1893, and heartwater caused by Ehrlichia ruminantium Cowdry 1925. A cross-sectional survey was undertaken to determine the antibody prevalence of these TBDs and to identify the risk factors for TBD infections in the Union of the Comoros. In 2016 and 2017, 903 individual animal serum samples were collected from 429 separate farms, where the farmers answered individual questionnaires. The antibody prevalence of anaplasmosis, babesiosis (B. bigemina) and heartwater was determined by enzyme-linked immunosorbent assays (ELISA) and the antibody prevalence of ECF was assessed using an immunofluorescence antibody test (IFAT). The relationship between TBD seropositivity and livestock-related variables was assessed by multivariate analyses with standard logistic regression models. The results showed that these four TBDs were present in the Union of the Comoros with a global antibody prevalence of 15% (95% CI [12.7%; 17.3%]) for anaplasmosis, 9.2% (95% CI [6.5%, 11.9%]) for B. bigemina babesiosis, 5.3% (95% CI [3.2%, 7.4%]) for ECF and 4.6% (95% CI [3.2%, 6%]) for heartwater. We compared these findings with the abundance and distribution of several tick species known to be TBD vectors and we found a significant correlation between Rhipicephalus appendiculatus and ECF, and between Amblyomma variegatum and heartwater. We also found that two major variables were significantly correlated with B. bigemina antibody prevalence ("island" and "breeding area"), four variables were significantly correlated with anaplasmosis antibody seroprevalence ("island", "number of cattle per farmer", "number of farmers per village" and "breeding area"), two were significantly correlated with ECF antibody prevalence ("number of farmers in village" and "presence of ticks"), and three were significantly correlated with heartwater ("island", "number of cattle per farmer" and "number of farmers in the village"). Our findings confirmed livestock exposure to the four targeted TBDs of major concern for livestock development. Consequently, raising farmers' awareness and setting up a period of quarantine should be considered a priority.

Impact of East Coast fever on Grande Comore: assessment taking a participatory epidemiology approach.

East Coast fever (ECF), one of the most serious tick-borne diseases in sub-Saharan and eastern Africa, was introduced to the island of Grande Comore in 2002 through zebu import from Tanzania, resulting in at least a 10% loss of livestock. A participatory epidemiology initiative was launched in 2015 to gain a better understanding of ECF epidemiology. Thirty-six villages were investigated involving 36 focus group sessions and 120 individual questionnaires. Farmers' knowledge of ECF and of priority diseases affecting the country was assessed, and the impacts of ECF and other major diseases were compared by a scoring method. The results showed that 69.4% (95% CI [51.3, 87.5%]) of the farmers had good to very good knowledge of ECF. The most important cattle diseases on Grande Comore were considered to be East Coast fever, heartwater, babesiosis, and cutaneous diseases. About 58% of the farmers (95% CI [49.2, 66.8%]) use curative treatments when cattle were sick. Between January and September 2015, the ECF incidence was estimated at 18.5% (95% CI [15.5, 21.4%]), and 87.5% (95% CI [72.7, 100%]) of the cattle infected by ECF died. The ECF incidence estimated in our study was found to be less when compared to that observed in Tanzania even though the climatic conditions in the Union of the Comoros are suitable for the biological vector of ECF, the tick species Rhipicephalus appendiculatus. Access to chemical treatment and its effectiveness against ECF, as well as controlling borders and organizing quarantine, are discussed.

Impact and Epidemiological Investigations into the Incursion and Spread of Peste des Petits Ruminants in the Comoros Archipelago: An Increased Threat to Surrounding Islands.

Late October 2012, a great number of deaths of unknown origin occurred in goat herds in the suburbs of Ngazidja, located in the Comoros archipelago. Few weeks later, laboratory testing requested by the animal health authorities resulted in the identification of peste des petits ruminants (PPR) infection. Notably, the Index case could be attributed to a sick goat imported from Tanzania. Viral isolation was successful from the lungs leading to the whole N nucleoprotein gene sequencing. Phylogenetic analysis revealed that the strain belongs to the lineage III which includes strains of eastern African origin. In addition, to evaluate the impact of PPR on the Comorian indigenous domesticated ruminant population, a cross-sectional PPR serological survey was conducted between April and July 2013. A low overall PPRV antibody prevalence 2.24% (95% CI [1.38; 3.08]) was detected with a Grande Comore prevalence of 3.34% (IC = [2.09; 4.63]) with a limited spread of the disease mainly due to farm practices such as limited contacts between farm animals and rapid slaughtering of sick animals.