Small ruminant breeding appears to be an opportunity for income generation in the context of poverty alleviation in some African countries (Duteurtre et al., 2002; Dedieu et al., 2011; Iñiguez, 2011; Orskov, 2011; MUSALLAM et al., 2015) . This is the case in Cameroon, where small ruminants (sheep and goats) play a very important role in the pastoral economy, accounting for 20% of the protein needs of Cameroonians (Njoya, 2010). This production is mainly concentrated in the northern regions of Cameroon (INS, 2019). Toxoplasmosis has a wide distribution in these areas unlike abortive chlamydia and is very harmful to both human and animal health. In combination with this, they cause significant economic losses in the livestock industry in these areas. This study provides substantial epidemiological data on the seroprevalence of toxoplasmosis and abortive chlamydia in small ruminant livestock in Cameroon.
The individual seroprevalence of Toxoplasma gondii obtained in the present study (31.01% (329/1061) with 35.93% in sheep and 25.91% in goats) was lower than those obtained in Burkina Faso (58.8%) (Bamba et al., 2012), in Tunisia (36.8%) (Lahmar et al., 2015), in Spain (37.31%) (García-Bocanegra et al., 2013) and in China (61.65%) (Li et al., 2021). However, lower prevalence have been found in small ruminants in Mexico (14.8%) (María de la Luz et al., 2022), in Mali (4.47 %) (Sidibe et al., 2019), in Pakistan (19.88%) (Tasawar, 2010), in Nigeria (11.29%) (Kamani, Mani and Egwu, 2010) and in Bangladesh (12.2%) (Sah et al., 2018). The different sero-detection techniques used could explain the differences observed. Moreover, the studies carried out in hot zones sometimes reaching temperatures of 45⁰C, did not favour the survival of oocysts in the environment for more than an hour thus limiting the indirect mode of transmission (Kamani, Mani and Egwu, 2010; Bamba et al., 2012; Sidibe et al., 2019). For abortive chlamydia, the seroprevalence of 4.24% obtained was lower than those obtained in Eastern Saudi Arabia (21.7%) (Fayez et al., 2021), in Western Turkey (25.81%) (Malal, Karagül and Akar, 2020) in Jordan (19.06%) (Al-Qudah et al., 2004). This remains similar to that recorded in Mali (3.55%) (Sidibe et al., 2019). This difference results from the variation in climatic conditions in the study areas noted by some authors, but also from differences between sheep and goat breeds, husbandry practices, hygiene, timing of sampling and the serological test used (Qin et al., 2015; Fayez et al., 2021). However, this study showed no signiﬁcant difference in the seroprevalence of Chlamydia abortus antibodies between sheep and goats at the individual level.
A co-infection of 1.82% (95% CI: 0.37 - 3.27) was obtained between Toxoplasma gondii and Chlamydia abortus in the present study. The presence of Chlamydia abortus in small ruminant farms would significantly (p=0.02) increase the risk of Toxoplasma gondii infestation. This co-infection was reported in the 2013 study by Romano and Coppens, where it was shown that Toxoplasma and Chlamydia tend to conform to their respective intracellular developmental programs, regardless of the presence of the other organism in the cell. The normal growth of each pathogen is highly dependent on the ability of the pathogen to maintain a threshold level of interaction between its vacuole and host cell organelles (Romano and Coppens, 2013). However, an infection with Chlamydia abortus could create a depressed state in the animals, thus allowing an infestation with Toxoplasma gondii.
Univariate analysis in this study showed that region (p=0.0001), species (p=0.0001), sex (p=0.0002), age (p=0.0002) and breed (p=0.01) were the risk factors associated with Toxoplasma gondii seroprevalence on small ruminant farms in Cameroon. The breed (p=0.0001) and the presence of abortion (p=0.0003) were identified as risk factors strongly associated with the seroprevalence of Chlamydia abortus. The Adamawa region (46.04% (95% CI: 39.16 - 52.9) had significantly (p=0.0001) high Toxoplasma gondii seroprevalence. This region has a savannah climate with a dry winter according to the Köppen-Geiger classification, unlike the other regions in the study (North and Far North). Rainfall in this region is much higher in summer than in winter. Over the year, the average temperature in Adamawa is 21.8°C and the average rainfall is 951.9 mm (Données-Mondiale, 2022). This type of climate favours the development and expansion of this pest (Qin et al., 2015; Fayez et al., 2021). The sheep species was significantly more infected (35.93% (95% CI: 31.87 - 39.97)) (p=0.0001) with Toxoplasma gondii than the goats in these areas. This result was similar to those obtained in Nigeria (Kamani, Mani and Egwu, 2010), in Southern Spain (García-Bocanegra et al., 2013) and in Tunisia (Lahmar et al., 2015). Sheep are generally associated with large cattle for grazing unlike goats, which favours greater contact with this infectious agent. Females (33.94% (95% CI: 30.60 - 37.26)) tested significantly more infested with Toxoplasma gondii than males as observed in the Lahmar study in Tunisia (Lahmar et al., 2015); probably due to greater sensitivity to protozoan parasites in females than in males (Alexander and Stimson, 1988).
Small ruminants aged 3-5 years were significantly more infested with Toxoplasma gondii than young animals (41.90% (95% CI: 36.16 - 47.64)). This observation was also highlighted by Qin et al. (2015) and was associated with continuous and increasing exposure to infectious oocytes in the environment (Qin et al., 2015). The Oudah breed in the sheep species was significantly more infected with Toxoplasma gondii (38.38%) than the other breeds and the Sahel goat in the goat species was more infected with Chlamydia abortus (33.33%). These breeds were used in sedentary, transhumant or nomadic farming systems which favours their permanent contact with these pathogens (Meyer, Faye and Karembe, 2004). The occurrence of abortions on small ruminant farms in our study was strongly associated with Chlamydia abortus infection as mentioned in the report of the Observatory and monitoring of the causes of abortions in ruminants Report 2019 (SCAR, 2020). This could be justified by the fact that Chlamydia abortus is the leading cause of abortion in small ruminants (the second being Campylobacter) although its prevalence was low in this study (Guillaume and Maud, 2017).