Abstract

Background and Aim: Q fever, caused by Coxiella burnetii, is a globally distributed zoonosis with major public health and livestock production implications. Dromedary camels (Camelus dromedarius) are increasingly recognized as important reservoirs, particularly in arid and semi-arid regions. In Jordan, however, comprehensive national-level data integrating serology, molecular detection, and spatial epidemiology are lacking. This study aimed to estimate the serological and molecular prevalence of Q fever in camels, identify associated risk factors, and describe the spatial distribution of infection across Jordan. 

Materials and Methods: A nationwide cross-sectional study was conducted between July and October 2022 using a two-stage cluster sampling design. A total of 468 camels from 31 villages across all camel-rearing governorates were sampled. Serum samples were tested for anti-C. burnetii antibodies using a commercial indirect multi-species enzyme-linked immunosorbent assay, while whole blood was examined for C. burnetii DNA using conventional polymerase chain reaction (PCR) assays targeting IS1111 and CB-1 genes. Survey-weighted prevalence estimates were calculated, and risk factors were evaluated using univariate and multivariate survey-weighted logistic regression. Spatial distribution was mapped at the governorate level. 

Results: The weighted prevalence of Q fever was 88.75% (95% confidence interval: 79.26%–98.23%) using parallel interpretation of serological and molecular tests. Individually, prevalence was 44.02% by enzyme-linked immunosorbent assay and 68.93% by PCR. Significant risk factors included age ≥3 years, contact with other camel herds, Sofor breed, light or absent tick infestation, and improper disposal of abortion materials. Co-herding with other species and a history of abortion were associated with reduced odds of positivity. Marked spatial heterogeneity was observed, with the highest prevalence in Tafilah governorate and the lowest in Zarqa. 

Conclusion: This first nationwide, integrated serological, molecular, and spatial study demonstrates an exceptionally high burden of Q fever in Jordanian camels, highlighting their critical role as a reservoir. The findings underscore the urgent need to incorporate camels into national Q fever surveillance and control programs within a coordinated One Health framework involving animal, human, and environmental health sectors. 

Keywords: camel epidemiology, Camelus dromedarius, Coxiella burnetii, Jordan, molecular detection, Q fever, risk factors, spatial distribution.