Viral and Bacterial Zoonotic Agents in Dromedary Camels from Southern Tunisia: A Seroprevalence Study.

The rapid spread of SARS-CoV-2 clearly demonstrated the potential of zoonotic diseases to cause severe harm to public health. Having limited access to medical care combined with severe underreporting and a lack of active surveillance, Africa carries a high burden of neglected zoonotic diseases. Therefore, the epidemiological monitoring of pathogen circulation is essential. Recently, we found extensive Middle East respiratory syndrome coronavirus (MERS-CoV) prevalence in free-roaming dromedary camels from southern Tunisia. In this study, we aimed to investigate the seroprevalence, and thus the risk posed to public health, of two additional viral and two bacterial pathogens in Tunisian dromedaries: Rift Valley fever virus (RVFV), foot-and-mouth disease virus (FMDV), Coxiella burnetii and Brucella spp. via ELISA. With 73.6% seropositivity, most animals had previously been exposed to the causative agent of Q fever, C. burnetii. Additionally, 7.4% and 1.0% of the dromedaries had antibodies against Brucella and RVFV, respectively, while no evidence was found for the occurrence of FMDV. Our studies revealed considerable immunological evidence of various pathogens within Tunisian dromedary camels. Since these animals have intense contact with humans, they pose a high risk of transmitting serious zoonotic diseases during active infection. The identification of appropriate countermeasures is therefore highly desirable.

Prevalence of Middle East Respiratory Syndrome Coronavirus in Dromedary Camels, Tunisia.

Free-roaming camels, especially those crossing national borders, pose a high risk for spreading Middle East respiratory syndrome coronavirus (MERS-CoV). To prevent outbreaks, active surveillance is necessary. We found that a high percentage of dromedaries in Tunisia are MERS-CoV seropositive (80.4%) or actively infected (19.8%), indicating extensive MERS-CoV circulation in Northern Africa.

First serological evidence of the Rift Valley fever Phlebovirus in Tunisian camels.

Rift Valley fever (RVF) is a mosquito-borne zoonosis that severely impacts livelihoods, national and international economies, and human health. Few studies have investigated the prevalence of this infection in Tunisian livestock. The present report aimed to update the epidemiological status and identify the risk factors associated with this RVF virus infection in the one-humped dromedary camel from arid areas. A total of 470 sera of apparently healthy camels (Camelus dromedarius) were collected from six governorates from southern and central Tunisia. Samples were tested by a competitive Enzyme Linked Immunosorbent Assay (ELISA). An overall, 162 camels (34%, 95%CI: 0.1-0.4) were seropositive to RVF virus antigen. Logistic regression model revealed three potential risk factors associated with the infection. A meaningful high seropositivity was observed among aged camels (>10 years-old) (40%) (P=0.001; OR=3.367). Besides, camels raised in small flocks particularly intended for meat production showed a high level of seropositivity (37%) (P=0.013; OR=13.173). Animals having close contact with other ruminants showed high seroprevalence (37%) (P=0.022; OR=10.919). This report indicated that Tunisian one-humped dromedaries were exposed to this virus and may contribute to its dissemination among farmers and other livestock. Furthers studies are urgently required to isolate and characterize this virus, evaluate the potential risk of human infection particularly in farmers, veterinarians and slaughterhouse workers and finally to program a serious strategy for RVF control.