Rickettsial exposure in ruminants from Somalia

Area of Science:

• Veterinary Microbiology
• Zoonotic Diseases
• Public Health Entomology

Background:

• Rickettsia species are Gram-negative, obligate intracellular bacteria transmitted by ticks, posing zoonotic risks.
• Rickettsiosis status in Somalia's livestock and human populations remains largely uncharacterized.
• Amblyomma ticks are vectors for Rickettsia africae, a significant zoonotic pathogen.

Purpose of the Study:

• To investigate the serological evidence of Rickettsia species exposure in livestock in Somalia.
• To determine the prevalence of antibodies against Rickettsia africae and Rickettsia rhipicephali in ruminants.
• To assess potential zoonotic implications of Rickettsia spp. in the studied regions.

Main Methods:

• Cross-sectional study involving 372 serum samples from goats, cattle, and sheep in Benadir and Lower Shabelle regions.
• Indirect immunofluorescence assays (IFA) used to detect antibodies against R. africae and R. rhipicephali.
• Serological analysis with two-fold serial dilutions starting from 1:64.

Main Results:

• Overall seropositivity for Rickettsia spp. was 50.5% (188/372) with titers ranging from 1:64 to 1:2048.
• R. africae antibodies detected in 21.0% (78/372), R. rhipicephali in 10.2% (38/372), and co-reactivity in 19.4% (72/372).
• Cattle exhibited the highest seroreactivity (90.2%), followed by sheep (28.6%) and goats (28.4%). Cattle and sheep were significantly more likely to be seropositive than goats.

Conclusions:

• This study presents the first serological evidence of Rickettsia spp. exposure in ruminants in Somalia.
• Cattle demonstrate a heightened susceptibility to Rickettsia infection, suggesting their role as potential sentinels for human exposure.
• Findings highlight the need for further investigation into Rickettsia spp. prevalence and associated zoonotic risks in Somalia.