Small Ruminant Brucellosis: Serological Survey in Yabello District, Ethiopia

RESULTS

Overall prevalence: In this study total of 384 small ruminant sera samples (213 goats and 171 sheep) were subjected to RBPT for screening and RBPT positive sera were subjected to CFT for confirmation. Among the total 384 sera sample tested, 9 (2.34%) were positive for brucellosis by RBPT. The sera screened positive by RBPT were retested using CFT and 6 sera were found positive for Brucella antibodies. Therefore, the overall prevalence of brucellosis in small ruminants this study was proved to be 1.56%.

Potential risk factors of small ruminant brucellosis: The prevalence of brucellosis in this study in sheep and goat was found to be 1.17 and 1.88%, respectively. Statistical analysis revealed that there was no significant difference (p>0.05) in the seroprevalence of Brucella antibodies between the two species (Table 1).

Small ruminant brucellosis among male and female animals was known to be 0.68 and 2.10%, respectively. Statistical analysis revealed that there was no significant different (p>0.05) in the seroprevalence to Brucella antibodies between male and female animals (Table 2).

Prevalence of small ruminant brucellosis in young animals was 0% while that of adult was 2.30%. Statistical analysis of the data showed that there was no significant difference (p>0.05) in the seroprevalence of Brucella antibodies and age group (Table 3).

Questionnaire survey: In this survey, 89 household heads were interviewed and their responses were summarized as follows:

History of occurrence and stage of abortion: Out of the 89 household heads interviewed 80 (90%) proved the occurrence of abortion to be associated with the disease in the sheep and goats in their flock and 34 (42.5%) reacted that abortion occurs more frequently in sheep while 46 (57.5%) responded it happens more frequently in goats (Table 4). Out of 80 interviewed, 42 (52.8%) responded it happens at late stage of pregnancy. Again out of 80 interview 57 (71.6%) responded that abortion occurs in animals kidding/lambing for first time (Table 4).

History of retention of fetal membranes and method of discarding: Out of 89 respondents, 33 (37%) of respondent have awareness of retention of fetal membranes (RFM) due to the disease in sheep and goats in their flock. The respondent also asked about method of handling and discarding of the fetal membranes, aborted fetus, uterine fluid and of these interviewees, 82 (92.1%) replied that they threw to open environment. About 88 (98.88%) respondents replied that they handled aborted fetus and fetal membranes without protective gloves (Table 5).

Table 1:	Seroprevalence of small ruminant brucellosis between species

Table 2:	Seroprevalence of small ruminant brucellosis between sexes

Table 3:	Seroprevalence of small ruminant brucellosis between ages
F: Frequency

Table 4:	Abortion-Occurrence, stage of pregnancy and parity number
F: Frequency

Table 5:	Occurrence, handling and discarding method of aborted fetuses and fetal membranes
F: Frequency

Table 6:	Milk consumption habit and method of consumption
F: Frequency

Milk consumption habit and method of consumption: Out of 89 members of the interview 88 (98.88%) replied that they consume sheep and goats milk and only 1(1.12%)) answered do not consume sheep and goats milk. With regard to the method of consumption, 63 (71.6%) replied that they consume boiled and 25 (28.4%) replied they consumed raw (Table 6).

DISCUSSION

The overall seroprevalence of small ruminant brucellosis in Yabello district of Borana zone was proved to be 1.56% (6/384). The species specific prevalence of the disease was confirmed to be 1.88 and 1.17% in goats and sheep, respectively. The finding of the current study was in agreement with the finding of Bekele et al. (2011), around Jijiga, who showed prevalence of 1.61 and 2.0% in sheep and goats, respectively and Tshale et al. (2006) in Somali region who proved prevalence of 1.6 and 1.7% of brucellosis in sheep and goats, respectively.

The prevalence of brucellosis in small ruminants in this study was relatively lower than the finding by Ashenafi et al. (2007), who reported the prevalence of 3.2% in sheep and 5.8% in goats in pastoral regions of Afar. The difference might be due to differences in the sample size or the variation in herding practices. In the Afar region, mixing of animals from the various areas is common at communal grazing and watering areas. In Borana pastoralist there is cultural indigenous range and water holes management knowledge governing pasture and water holes and thus settlement is based in some predetermined scenario which allow some group of the community or clan to use the resource (Oba, 1998).

The prevalence of brucellosis in this study in sheep and goat was found to be 1.17 and 1.88%, respectively. Statistical analysis revealed that there was no significant difference in the seroprevalence to Brucella antibodies between the two species (p>0.05). This could be attributed to the fact that sheep are at higher risk of acquiring Brucella infection than goats (Radostitis et al., 2000).

Small ruminant brucellosis among male and female animals was known to be 0.68 and 2.10%, respectively. Statistical analysis revealed that there was no significant different (p>0.05) in seroprevalence to Brucella antibodies between male and female animals. This could be best justified by the fact that male animals are less susceptible to Brucella infection, due to the absence of Erythritol (Dwight and Yuen, 1999).

The prevalence of small ruminant brucellosis in young animals was 0% while that of adult was 2.30%. Statistical analysis of the data showed that there was no significant difference in seroprevalence to Brucella antibodies and age group (p>0.05). This fact might be explained by the fact that brucellosis is essentially a disease of sexually mature animals. Younger animals tend to be more resistant to infection and frequently clear an established infection, although latent infections can occur (Quinn et al., 1994; Walker, 1999).

Awareness of the community about the occurrence of abortion in relation to the stage of pregnancy and parity number has been assessed through interview. Accordingly greater proportion of the respondents replied that it takes place in later stages of pregnancy and in animals kidding/lambing for first time.

The respondents were asked about method of handling and discarding of the fetal membrane, aborted fetus, uterine fluid and greater proportion of the respondents replied that they throw to open environment and they handle without protective glove. Throwing to the environment might also expose the materials to the dog which act as mechanical vector of brucellosis, handling and contact of such material plays important role in transmitting the disease in small ruminant and man.

Milk consumption habit and method of consumption were also assessed and almost all replied that they consume sheep and goats milk, method of consumption asked and majority replies they consume boiled. Since there is close contact between humans and their livestock, which sometimes share the same housing enclosures, brucellosis is a significant health risk for the entire community.

Awareness of the community about transmission of small ruminant brucellosis to human was tried to assess by open-ended question and majority of the interviews explain that, if pregnant woman consumes milk from aborted animals, she might also abort. In addition, this idea in the community might reduce risk to the women in some amount. This idea also agree with scientific actuality that, the virulence of B. melitensis partly measured by their capacity to cause brucellosis in human being and cattle, that are not considered natural or preferred host, even though in this species the disease sporadically lead to abortion (Davidson et al., 1990).

CONCLUSION

This study indicated that brucellosis was known to occur among small ruminant in Yabello district of Borana zone, Ethiopia. Species, sex and age of the animals were proved to influence the occurrence of brucellosis among small ruminants. The occurrence of brucellosis among small ruminants in the study area might poses a huge productivity and reproductivity problem among small ruminants and will be a public health risk to the human population in the area. Therefore, attention towards best control and prevention methods brucellosis among small ruminants is essential to mitigate the economic losses in the sheep and goat industry in the study area in particular and the country as a whole. Thus, the results warrant further investigations to elucidate the animal and human health significance small ruminant brucellosis in the area.

ACKNOWLEDGMENTS

The work incorporated in this study was undertaken using the research grant allocated by College of Agriculture and Veterinary Medicine, Jimma University. The researchers are grateful to the University in particular and government of Ethiopia, in general, for providing them the research fund.

We wish to express our gratitude to National Animal Health Diagnostic and Investigation Center (NAHDIC) at Sebeta, Ethiopia for the support we received in testing the samples. Lastly yet very importantly, the researchers would like to use this opportunity to thank sheep and goats owners in Yabello district of Borana zone, Oromia Regional State, Southern Ethiopia, who helped them in samples collection and contributing significantly in the work during the study.