Serological prevalence of Coxiella burnetii in captive wild ruminants in Saudi Arabia

Serological investigation of Coxiella burnetii infection (Query fever) in livestock in Makkah Province, Saudi Arabia

Background and Aim

Query fever (Q fever) is an endemic zoonotic disease and ruminants are considered to be the primary source of infection in humans. It is caused by Coxiella burnetii which is an obligate intracellular bacterial pathogen with a worldwide distribution. This study estimated the prevalence of Q fever in livestock with a history of abortion in Makkah Province, Saudi Arabia.

Material and Methods

Sera from 341 camels, 326 sheep, and 121 goats of either sex from various locations (Makkah, Jeddah, AL-Taif, AL-Qunfudah, AL-Laith, and AL-Kamil) were examined using a Q fever indirect enzyme-linked immunosorbent assay.

Results

Among the 788 serum samples, 356 animals had anti-Coxiella burnetii immunoglobulin G antibodies with an overall seroprevalence of 45.4%. Significant differences were observed in seroprevalence between species and locations. Camels had the highest percentage of Q fever-positive sera, with a prevalence of 50.4%, followed by goats (44.6%) and sheep (36.8%), with a high significant difference between animals (p = 0.000). The prevalence was significantly higher in Makkah (65.4%) than in Jeddah (28.8%).

Conclusion

C. burnetii infection is prevalent in agricultural animals, especially camels maintained at livestock farms in Makkah province. Therefore, these animals considered as the main source of Q fever infections in Saudi Arabia, which is also a reason for the abortion in these animals. Therefore, there is an urgent need for further studies on Q fever infection with interventional approaches for prevention and control.

Genetic diversity of wild rodents and detection of Coxiella burnetii, the causative agent of Q fever, in Saudi Arabia

Throughout history, wildlife has been regarded as a major source of infectious diseases. Rodentia, the most speciose order of mammals, whose members are recognised hosts of more than 60 zoonotic diseases, represent a potential threat to human health. Recently, epidemiological data from Saudi Arabia indicated an actual growth in the number of emerging and/or re-emerging cases of several zoonoses. However, there is a lack of studies focusing on the molecular taxonomy of rodents and the pathogens they may harbour in this region. In this study, the first molecular characterisation of six rodent taxa in this region is provided, based on partial Cyt B and 16S genes. The data confirm the spread of rodent-associated C. burnetii strains in Jazan, southwestern Saudi Arabia. The PCR targeting IS111, the multi-copy transposase gene, revealed 17.5% (36/205) positive samples, whereas the second nested PCR, targeting the single-copy Com1 gene, revealed 16.6% (34/205) positive samples. Phylogenetic and network analyses indicated the presence of four haplotypes of C. burnetii within the studied localities. One major haplotype (H-2) was observed in all rodent species and from 18 localities. The infection rates of C. burnetii among studied species, localities and habitats were not significantly different (>0.05). Our results facilitate the assessment of the health risk associated with rodents and the development of strategies to control the increasing impacts of Q fever.

Flock Management Risk Factors Associated with Q Fever Infection in Sheep in Saudi Arabia

Q fever is a zoonotic disease caused by Coxiella burnetii (C. burnetii), an intracellular, Gram-negative bacterium that infects humans and domestic ruminants. Information on flock management factors associated with Q fever seropositivity in Saudi Arabia is very scarce. Therefore, the objective of this study was to identify the animal and flock management factors associated with Q fever seropositivity. For the assessment of risk factors, a case-control study was carried out. Cases (n = 25) were flocks that had recent abortions within the previous two weeks and were PCR positive for C. burnetii. Control flocks (n = 25) had no history of recent abortion and were PCR negative for C. burnetii. A questionnaire was developed to collect information about the flock management risk factors possibly associated with Q fever exposure in sheep. A total of 2437 sheep serum samples, collected from infected (n = 1610, 10-150 samples/flock) and non-infected (n = 827, 10-65 samples/flock) flocks, were tested for C. burnetii antibodies using a commercial ELISA kit between May 2018 and April 2019. In addition, 521 samples, including 50 aborted materials, 173 vaginal swabs, 134 faecal, and 164 milk samples, were collected for PCR testing. Infected flocks were 100% seropositive (within-flock seroprevalence ranging between 13.8% and 60%) and 100% PCR positive (with animal shedders of C. burnetii through aborted materials and/or vaginal fluids, feces, and milk). However, in non-infected control flocks, 28% were seropositive (within-flock seroprevalence ranging between 6.7% and 20%) and none had C. burnetii shedders. Epidemiological data were analyzed using mixed-effect logistic regression with a random effect for the flock. The results identified three protective factors: flocks with a lambing pen (odds ratio (OR): 0.46; 95% CI: 0.28-0.76), change bedding after removing aborted materials (OR: 0.42; 95% CI: 0.23-0.76), and flocks that isolated aborted ewes (OR: 0.41; 95% CI: 0.25-0.67), as well as two risk factors: flocks infested with ticks (OR: 2.78; 95% CI: 1.65-4.70) and flocks with a history of Q fever (OR: 3.03; 95% CI: 1.42-6.50). These results could be used to improve sheep flock biosecurity measures to prevent the introduction and reduce exposure of sheep and humans to Q fever infection.

Seroprevalence and risk factors of Q-fever (C. burnetii infection) among ruminants reared in the eastern region of the Kingdom of Saudi Arabia

Q-fever is a worldwide spread zoonotic disease associated with severe illness in humans and abortions and stillbirths in ruminants. Ruminants are major sources of human infection where subclinical carriers shed the bacteria in various secretions and excreta. The goal of the current study was to investigate the prevalence and risk factors of Coxiella burnetii infection among cattle, sheep, and goats in the eastern province of the Kingdom of Saudi Arabia (KSA). A total of 1310 serum samples were collected through a designed cross-sectional study from private farms and slaughterhouses in the study area and examined against antibodies of C. burnetii using ELISA. A multivariate logistic regression analysis was built to detect risk factors of C. burnetii infection among examined species. The prevalence of C. burnetii infection among examined animals was 9.2% (CI, 7.7-10.8)-15.6%, 9.1%, and 5.8% among goats, cattle, and sheep, respectively). The risk of getting C. burnetii infection among old animals (> 1 year old) was 23 times higher than the risk among young animals (< 1 year old) (95% CI, 10.04-53.01; P < 0.01). Goats were 2.27 (95% CI, 1.41-3.66; P < 0.01) and 3 times at higher risk than cattle and sheep, respectively, of getting C. burnetii infection. In conclusion, C. burnetii infection is widespread among different ruminant species of the eastern province of KSA which represents a high risk for environmental contamination and disseminating the infection to humans and animal species in that area. Also, our findings may reflect the disease status in other countries of the Arabian Gulf area.

Long-Term Dynamics of Coxiella burnetii in Farmed Red Deer (Cervus elaphus)

Several aspects of the dynamics of Coxiella burnetii that are relevant for the implementation of control strategies in ruminant herds with endemic Q fever are unknown. We designed a longitudinal study to monitor the dynamics of exposure to C. burnetii in a red deer herd with endemic infection in order to allow the design of Q fever-specific control approaches. Other relevant aspects of the dynamics of C. burnetii – the effect of herd immune status, age, season, and early infection on exposure, the average half-life of antibodies, the presence and duration of maternal humoral immunity, and the age of first exposure – were analyzed. The dynamics of C. burnetii in deer herds seems to be modulated by host herd and host individual factors and by particular host life-history traits. Red deer females become exposed to C. burnetii at the beginning of their second year since maternal antibodies protect them after birth and during the main pathogen shedding season – at the end of spring-early summer. Infection pressure varies between years, probably associated with herd immunity effects, determining inter-annual variation in the risk of exposure. These results suggest that any strategy applied to control C. burnetii in deer herds should be designed to induce immunity in their first year of life immediately after losing maternal antibodies. The short average life of C. burnetii antibodies suggests that any protection based on humoral immunity would require re-vaccination every 6 months.