The first serosurvey of equine coxiellosis in Iran CURRENT STATUS: POSTED

Coxiella burnetii, Horse, Iran, Q fever, Serology. Abstract Background: Q fever is a hyper endemic zoonosis in middle east countries. In Iran, serologic studies have been done in cattle, sheep, goat, camel and human. There is any report of Q fever in horse populations and this study is the first serosurvey in this area. Results: A total of 177 serum samples from North and South of Iran were randomly collected and were analyzed for Q fever by a commercial ELISA kit. Anti C.burnetii antibodies were detected in 5.64% of sera samples. Results of this study indicated that there was no significant difference in seroprevalence in different sexes, ages and breed groups. Conclusions: This is the first report of Q fever in horses of Iran and our study shows that the impact of Q fever disease on horses' health status in the studied area appears to be important. However, Additional studies are needed to assess whether the horse can be used as a relevant transmission risk indicator for Q fever in this area.

Background Q fever is a zoonosis caused by Coxiella burnetii, a compulsory intracellular gram -negative bacterium capable of infecting both a wide range of animals and humans [1]. The organism is distributed worldwide, although serological surveys in New Zealand found no evidence of infection [2]. The seroprevalence of Q fever in regions and individual herds or flocks can be wide -ranging [3].
The horse's role as a C. burnetii reservoir infection was not adequately investigated. Serological evidence of C. burnetii infection in horses has long been reported. Study results were variable, ranging from non -detection of any evidence of infection [4] to An estimated 52.5 percent seroprevalence [5]. In addition, C. burnetii was suggested by a recent report as a potential abortifacient in French horses [6]. However, it remains unclear how horses are involved in the Q fever epidemiology [7,8]. In fact, the few serological surveys available [5,7,9,10] Suggest that horses can be exposed to C. burnetii naturally, but these studies are old and conducted with less sensitive serological tests than ELISA tests [11]. Furthermore, C. burnetii DNA Occasionally, was reported in samples of aborted equine or placental fetuses [6].
Just as recently reported cases of human Q fever from Iran [19].
There is no report on serology of Q fever in horses in Iran based on our knowledge. We studied the presence of anti -C.burnetii antibodies in horses in certain locations in Iran and showed that the impact of Q fever disease on horses ' health status in the studied area.

Results
Numbers of total serum and seropositive samples were presented in Table 1 in different locations, sex, breed and age groups. Anti -C. Burnetii antibodies were detected in 10 horses (8females and 2males), 9 horses belonging to the province of North Khorasan and 1 horse belonging to the province of Iran (p=0.026). The overall seroprevalence rate for horses was 5.64% (95% CI=2.7-10.1). Results of this study indicated that there was no significant difference in seroprevalence in different sexes, age and breed groups. Discussion p>Based on our knowledge, there is no report on Q fever serology in Iran's horses and this study is Iran's first research. The overall seroprevalence rate for horses in this study was 5.64 percent. Anti C. Burnetii antibodies in current research were detected in 10 horses (8 females and 2 males), 9

Seroprevalence of C. burnetii among horses in Poland and
horses belonging to the province of North Khorasan and 1 horse belonging to the Kerman province of Iran. (p=0.026). Horses are kept with goats in North Khorasan and given the rate of abortion in these goats; infectious agents such as Q fever can be easily transmitted from goats to horses. Bamberg and et al described a Q -fever outbreak associated with a horse -boarding ranch that had purchased two herds of goats. This Q -fever outbreak was caused by exposure to infected goats. A cohort analysis between ranchers and persons revealed statistically significant associations between goat contact and seropositivity [25]. In goats, several studies also show that latently infected but seemingly healthy goats can also shed the organism in their vaginal secretions [26].
Results of this study indicated that there was no significant difference in seroprevalence rates in different age (p=0.44) and breed groups (p=0.06); however, seroprevalence rates were higher in Torkaman horses. In this topic, there is any report compared to our results.
It is necessary to consider horses as reservoirs for C. Burnetii. The detection of C. burnetii DNApositive placentas in horses in the northern part of the Netherlands indicates that the contaminated environment has a true reservoir rather than a spillover effect in the south. Horses had previously been discussed as a risk factor in the outbreak of Q fever [8]. Detection of C. burnetii in equine aborted fetuses and neonates, suggested that C. burnetii together with other common pathogens, should probably be considered in equine abortion [6].

Conclusion
Serological results of present study provide indirect evidence that C. burnetii has been transmitted to horses in Iran. Our study shows that the impact of Q fever disease on horses' health status in the studied area appears to be low, but quite important. Additional studies are needed to assess whether the horse can be used as a relevant transmission risk indicator for Q fever in this area. Horses are typically a domestic species at the interface of infected domestic ruminants with humans, particularly in the areas studied.
One of the limitations of our study was the small number of positive cases that made it impossible for us to analyze statistics properly risk and epidemiological factors. The combination of molecular and serological testing provides the best understanding of the significance of Q fever in the horses' population.

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Availability of data and material: The raw data collected during the present study are available from the corresponding author upon request.