This study was undertaken to determine the seroprevalence of Q fever in domestic livestock in Saudi Arabia. Serum samples from 489 camels, 428 cattle, 630 sheep and 423 goats, of either sex, from different localities were tested for antibodies against C. burnetii using a Q fever indirect enzyme-linked immunosorbent assay (ELISA). A subsample of 307 animals of different species was simultaneously tested for C. burnetii antibodies by ELISA and indirect immunofluorescence (IFA). The overall seroprevalence was 30.71%. Prevalence by species was 51.53%, 30.67%, 34.04% and 12.38% in camels, cattle, goats and sheep, respectively. Significant differences in seroprevalence were recorded between species and locations. The prevalence was overtly higher in adult as compared to young animals. No significant difference was recorded between male and female animals. There was a close agreement between ELISA and IFA results in cattle and camels while the results of the two tests were at variance in sheep and goats. The results indicate that the domestic livestock and the camel are the source of Q fever endemicity in Saudi Arabia.

During 2012 and 2013, a total of 1970 serum samples from animals, comprising 428 cattle, 630 sheep, 423 goats and 489 camels of either sex were investigated for seroprevalence of antibodies against C. burnetii. The animals were selected randomly at farms, markets, slaughter-houses and free ranged herds in different locations. They were all divided into young (sexually premature) and adult (sexually mature) animals according to the following criterion: in bovines; young is less than 2 years and adult is equal to or more than three years - in sheep/goats young is less than 1 year and adult equal or more than 1 year and in camels young is less than 4 years and adult equal or more than 4 years. Camels belonged to Maghater, Majahim and mixed breeds; sheep belonged to Najdi, Naimi and Harri breeds and goats belonged to Ardi and Demasqi breeds. All cattle were locally born and bred Friesian-Holstein. The systems under which animals are kept are either intensive or extensive (housed). Animals held under intensive rearing system are those which are under the shade and food was provided in the same place while those under extensive system are kept in a paddock and they are allowed free ranging for few hours every day (free-ranged). All animals were clinically normal at the time of sampling, except some camels that harboured ticks. None of the adult female animals included in this study was pregnant while some females were lactating. Also, none of the sampled adult females had a history of abortion or stillbirth although many of them belonged to herds where abortions of unknown etiology have been previously recorded in some herd members.

The overall seroprevalence of Q fever in Saudi Arabian farm animals is 30.71%. This relatively high prevalence indicates that Saudi Arabia is an important endemic focus of Q fever. A close agreement between ELISA and IFA results is recorded in camels and cattle but not sheep and goats. The prevalence of Q fever in camels exceeds 51% reflecting the poor management and hygienic conditions under which these animals are kept and their frequent exposure to contaminated dust and sand during sandstorms in the desert. The high prevalence of Q fever in camels, coupled with the widespread habit of consuming raw camel milk, underscore the key role of camels in the transmission of human Q fever in Saudi Arabia. Efforts should, therefore, be made to reduce the prevalence of Q fever in the Kingdom’s animals using different control measures, including introduction of animal vaccination, and to protect workers at higher risk of exposure to infection.

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