# Serological Investigation and Epidemiological Analysis of Bovine Leptospirosis in Egypt
## 3 Results
### Serological and Epidemiological Findings  
This study found that 236 animals had antibodies against _Leptospira_, reflecting a seroprevalence of 39.33%. As shown in Table 2, cattle of small stakeholders from Dikirnis and Belkas presented the highest prevalence rate (11.33%), followed by those from Mansoura (8.67%), with animals from Sherbin locality showing the lowest recorded seroprevalence (8%).  
The epidemiological findings and potential risk factors associated with occurrence of the disease are shown in Tables 2-6. As mentioned earlier, Chi-square analysis of different assumed determinants of animals had antibodies against _Leptospira_ showed that age, sex, and clinical signs were significantly associated with the seropositivity to _Leptospira_. Regarding age, a significant association was observed between the frequency of ELISA-positive samples and age (\(p<0.0001\)). As illustrated in Table 3, all cattle aged over 1 year old showed higher prevalence rates than those \(<\)1 year old. However, the highest prevalence rate (22%, 132/600) was observed among those aged 3-5 years, whereas the lowest prevalence rate was recorded among those cattle \(<\)1 year old (2.66%). Regarding sex as a potential variable among the studied animals (Table 4), a significant difference was observed between male and female cattle (\(p\leq 0.0001\)). Notably, the highest infection rate was observed among  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Locality**} & **No. of** & **ELISA** & **ELISA** & **\(\chi^{2}\)** & \(p\)**-Value** & **Prevalence** \\  & **Examined** & **Positive** & **Negative** & **\(\chi^{2}\)** & **\(p\)**-Value** & **(\%)** \\ \hline Sherbin & 180 & 48 & 132 & 76.54 & \(<\)0.0001 ** & 8\% \\ \hline Dikrnis & 144 & 68 & 76 & 0.680 & 0.409 N.S & 11.33\% \\ \hline Belkas & 168 & 68 & 100 & 11.44 & 0.0007 ** & 11.33\% \\ \hline Mansoura & 108 & 52 & 56 & 0.167 & 0.683 N.S & 8.67\% \\ \hline Total & 600 & 236 & 364 & 35.76.81 & \(<\)0.0001 ** & 39.33\% \\ \hline \hline \end{tabular}  
*: Highly significant. N.S: Non-significant.  
\end{table}
Table 2: Prevalence of leptospirosis in cattle according to locality.  
female animals (35.33%), while male animals showed an infection rate of 4% (24/600). Moreover, a significant difference (_p_ < 0.0001) was noted between the frequencies of positive results via ELISA and different clinical signs recorded (Table 5). In this concern, the highest frequency rate of leptospirosis was reported in cattle who exhibited bloody milk 75% (24/32) followed by those that experience a drop in milk production 72.72% (32/44) and repeat breeders 66.67% (24/36). However, as shown in Table 5, a low frequency rate 26.92% (28/104) has been recorded for cattle with fever. Moreover, the frequency rates of leptospirosis in clinical and subclinical mastitis cases were 38.89% (28/72) and 28.57% (24/84), respectively. The present study used Binary Logistic Regression to determine predictors for the ELISA test result. Using univariate analysis of risk factors, it was found that age was the significant predictor for this, while the results of multivariate binary logistic function for clinical signs related to the infection revealed that repeated breeder and drop milk yield were best predictors with estimates (1.9 and 1.7), respectively, and they seem to be distinct predictors that can be used to predict ELISA results (Table 6). Furthermore, as depicted in Table 7, LDA was conducted to classify ELISA results using clinical signs and demographic data as predictors. Accordingly, our findings showed that 304/364 (83.5%) negative cases were correctly classified, whereas 120/236 (50.8%) positive cases were correctly classified, with an overall classification accuracy of 70.7%.