The overall prevalence of hydatidosis in cattle slaughtered at the municipal abattoir of Wolaita Soddo is estimated to be 60 (15%). This result aligns with previous studies reporting rates of 13.9%- 24% from different regions of Ethiopia (1–3, 7, 16, 30). Conversely, it is lower than earlier findings, such as 33.3% in Yabello (15), 40.2% in Hawasa (16), 44.6% in Shashemene (23), 55.7% in Jimma (31), 96.6% in Hawsa (32) from various parts of Ethiopia. This study is also higher than the earlier reports of 5.6% in Asella (33) and 6.5% in Debre Berhane (34), 10.7 in Haramaya (22) and 10.9 in Wolaita Sodo (9) from Ethiopia.
The variations in the prevalence mentioned above in different regions of the country can be attributed to the differences in the types of Echinococcus found in different geographical locations, as well as differences in culture, social behaviour, and attitudes towards dogs in those areas. The occurrence of hydatidosis was lower compared to other regions due to the origin of the slaughtered animals, with the majority of cases coming from lowland areas near the woreda. The environmental conditions, such as high temperature and low humidity, were unfavourable for the survival of Echinococcus eggs, contributing to the lower prevalence. Thompson and Mc Manus (35) suggested that environmental factors like humidity and temperature influence the natural selection of infective eggs from adult dog tapeworms. On the other hand, the higher prevalence can be attributed to information obtained from the Soddo veterinary clinic and Soddo town municipality, which have implemented a program to control rabies and associated diseases by destroying stray dogs without legal owners in the study area every 2–3 years. This program carried out in previous years, has helped reduce the dog population and interrupt the life cycle of hydatidosis. Urquhart et al. (36) also argued that in areas without specific measures for hydatidosis control, the incidental benefit of destroying stray dogs for rabies control has a significant impact on reducing hydatidosis in both humans and animals.
There is no statistically significant risk factors were identified for hydatidosis (P ≥ 0.05) in this study. This finding is consistent with previous studies (1, 2, 16, 37) and contradicts the earlier reports (2, 7, 8, 15, 34). Nevertheless, animals were exposed to hydatidosis infection regardless of their body shape and condition, as people in the area preferred meat from fat animals, particularly for cutting meat consumption (‘’Kurt’’). The prevalence of hydatidosis tends to increase with the age of the animal (cattle) due to the practice of culling infected young cattle early by selling or slaughtering them before they reach old age, as older cattle have lower acquired immunity against hydatid infection. This is supported by the fact that Taeniid eggs cannot develop into metacestode in older animals (1, 16, 38). Additionally, the number of ingested eggs by the intermediate host depends on the level of contamination and the infectivity of the eggs (39).
Regarding the size of hydatid cysts, out of the 176 cysts recovered from 60 cattle with hydatidosis in this study, it was more observed in small sizes (47.7%) than medium (29.5%), and large size cysts (22.7%). This finding is supported by the findings of Belachew et al.(7) and Kumsa(2). However, Gautama and Pal (8), and Kebede and Zekarias (23) contradict these findings who stated that large and medium cyst cysts were more observed than the small size cyst of Bovine Hydatidosis harboring. This distribution may be attributed to the fact that a higher number of cysts are small in size due to the infected cattle being slaughtered before the cysts grow larger, and the limited immune response of the hosts to contain these cysts (40). The intermediate hosts and the characteristic lesions of hydatidosis are fluid-filled cysts that develop slowly over several months, with large cysts often found in older animals (41).
The predilection sites of hydatid cysts in the internal organs of examining cattle were more observed in the lungs (20.5%) followed by the liver (15.25%), spleen (3.5%) and kidney (4.75%) in the study area. This suggests that the presence of cysts was more prominent in the lungs compared to the liver and other organs. This observation is consistent with previous studies (1–3, 7–9, 16, 23). The higher prevalence of calcified cysts in the liver may be due to the relatively higher reticuloendothelial cells and abundant connective tissue reaction of the organ (42). Additionally, the lungs and liver serve as the primary capillary sites for migrating oncospheric echinococcus (hexane embryo) (17, 43).
A total of 176 cysts were recovered from 60 cattle harboured by hydatidosis. Among these cysts, the percentage of sterile cysts (59.1%) was higher than fertile ones (40.9%). This sterile cyst was also more encountered in the spleen than in other internal organs in the study area. The findings of this study align with those of previous research (1, 2, 8, 16, 17). Nevertheless, this finding is contradicted by earlier studies in Ethiopia which stated that fertile cysts are more observed than sterile cysts (7, 15, 23). The reduced fertility of hydatid cysts observed in this research could be attributed to the younger age of the cattle under examination, as older animals tend to have a higher number of fertile cysts. Previous studies have indicated that fertile cysts take longer to develop in livestock (44). This notion was further supported by Soulsby (41), who suggested that fertile cysts are more commonly found in older animals, while sterile cysts are prevalent in younger animals. It is also known that cysts can be either fertile or sterile, with the ratio of sterile cysts varying among different host species: over 90% in cattle, 20% in pigs, and 8% in sheep (20). However, the fertility rates of cysts may differ based on factors such as geographical location, host species, cyst site, size, and type (45). Hydatidosis is a significant zoonotic disease with implications for public health and the economy in many countries worldwide. The prevalence of hydatidosis in a particular area may be influenced by various social, cultural, environmental, and epidemiological factors (43). The limitations of this study included the security problem as well as constraints related to funding, equipment, and reagents.