Abstract
Fever is not a disease in itself but it is a symptom that indicates a disease in the body. Fever of unknown origin (FUO) was defined as a temperature of 38.3 °C or higher with a minimum duration of 3 weeks without an established diagnosis after an intensive 1-week investigation in the hospital. The current study was carried out for detection of some possible zoonotic causes of FUO. A total of 200 serum samples collected from patients attending Fever hospitals were subjected to serological examination for detection of Brucella antibodies by Rose Bengal plate test (RBPT) as well as detection of antibodies of Toxoplasma gondii, Leishmania infantum and Rickettsia conorii by Enzyme Linked Immunosorbent Assay (ELISA). It was recorded that the overall frequency of detection of Brucella was 9% and males (14.6%) showed higher detection rate compared to that of females (4.5%). In addition, the highest detection rate was observed in age group 45 – 65 years (15.9%) followed by the age group 15 - < 30 years (9.2%) then the age group 30 - < 45 years (5%) with statistical significant association between these frequencies. Also, the overall frequency of detection of T. gondii Abs was 6% and females (6.3%) showed higher detection frequency compared to that of males (5.6%) with statistical significant association. Moreover, the highest detection rate was observed in age group 15 - < 30 years (7.9%) followed by the age group 45 – 65 years (6.8%) then the age group 30 - < 45 years (3.8%) with statistical significant association between these frequencies. Serological investigation of L. infantum clarified that only three samples showed serological reaction with percentage of 1.5 %. In addition, males’ frequency was higher than that of females (2.24 % vs 0.9%) with non-significant association between them. Moreover, the age group impact on the detection rate also showed non-significant association. Finally, serological investigation of Rickettsia conorii also clarified that only three samples showed serological reaction with percentage of 1.5%. In addition, males’ frequency was higher than that of females (2.25 % vs 0.9%) with non-significant association between them.

Key words: Seroepidemiology, FUO, Brucella, Toxoplasma, Leishmania, Rickettsia