Evaluation ofCoxiella burnetiiStatus in Dairy Cattle Herds with Bulk-tank Milk Positive by ELISA and PCR

Coxiella burnetii abortion in a dairy farm selling artisanal cheese directly to consumers and review of Q fever as a bovine abortifacient in South America and a human milk-borne disease

Coxiella burnetii is a highly transmissible intracellular bacterium with a low infective dose that causes Q fever (coxiellosis), a notifiable zoonotic disease distributed worldwide. Livestock are the main source of C. burnetii transmission to humans, which occurs mostly through the aerogenous route. Although C. burnetii is a major abortifacient in small ruminants, it is less frequently diagnosed in aborting cattle. We report a case of C. burnetii abortion in a lactating Holstein cow from a dairy farm producing and selling artisanal cheese directly to consumers in Uruguay, and review the literature on coxiellosis as a bovine abortifacient in South America and as a milk-borne disease. The aborted cow had severe necrotizing placentitis with abundant intratrophoblastic and intralesional C. burnetii confirmed by immunohistochemistry and PCR. After primo-infection in cattle, C. burnetii remains latent in the lymph nodes and mammary glands, with milk being a significant and persistent excretion route. Viable C. burnetii has been found in unpasteurized milk and cheeses after several months of maturing. The risk of coxiellosis after the consumption of unpasteurized dairy products, including cheese, is not negligible. This report raises awareness on bovine coxiellosis as a potential food safety problem in on-farm raw cheese manufacturing and sales. The scant publications on abortive coxiellosis in cattle in South America suggest that the condition has probably gone underreported in all countries of this subcontinent except for Uruguay. Therefore, we also discuss the diagnostic criteria for laboratory-based confirmation of C. burnetii abortion in ruminants as a guideline for veterinary diagnosticians.

Molecular detection of Coxiella burnetii infection in small mammals from Moshi Rural and Urban Districts, northern Tanzania

Coxiella burnetii is an obligate intracellular bacterium that causes Q fever, a zoonotic disease of public health importance. In northern Tanzania, Q fever is a known cause of human febrile illness, but little is known about its distribution in animal hosts. We used a quantitative real-time PCR (qPCR) targeting the insertion element IS1111 to determine the presence and prevalence of C. burnetii infections in small mammals trapped in 12 villages around Moshi Rural and Moshi Urban Districts, northern Tanzania. A total of 382 trapped small mammals of seven species were included in the study; Rattus rattus (n = 317), Mus musculus (n = 44), Mastomys natalensis (n = 8), Acomys wilson (n = 6), Mus minutoides (n = 3), Paraxerus flavovottis (n = 3) and Atelerix albiventris (n = 1). Overall, 12 (3.1%) of 382 (95% CI: 1.6-5.4) small mammal spleens were positive for C. burnetii DNA. Coxiella burnetii DNA was detected in five of seven of the small mammal species trapped; R. rattus (n = 7), M. musculus (n = 1), A. wilson (n = 2), P. flavovottis (n = 1) and A. albiventris (n = 1). Eleven (91.7%) of twelve (95% CI: 61.5-99.8) C. burnetii DNA positive small mammals were trapped within Moshi Urban District. These findings demonstrate that small mammals in Moshi, northern Tanzania are hosts of C. burnetii and may act as a source of C. burnetii infection to humans and other animals. This detection of C. burnetii infections in small mammals should motivate further studies into the contribution of small mammals to the transmission of C. burnetii to humans and animals in this region.

Coxiella burnetii in the environment: A systematic review and critical appraisal of sampling methods

Q fever is a zoonotic disease caused by the intracellular bacterium, Coxiella burnetii. Its primary mode of transmission is by inhalation of aerosols originating from infected animals and contaminated environments. The organism has a very low infective dose, can persist in the environment for long periods of time and large outbreaks fuelled by windborne spread have been previously reported. Detection of C. burnetii in the environment is therefore important during human and animal outbreak investigations and for the control and prevention of Q fever. This study aimed to systematically review and critically appraise the published literature on sampling methods used to detect C. burnetii from different environmental samples. A search of four electronic databases with subsequent hand searching identified 47 eligible articles published since 1935. These articles described sampling of dust, air, soil and liquids in attempts to detect C. burnetii during 19 Q fever outbreaks and in 28 endemic settings. Environmental positivity was most commonly associated with ruminant livestock populations. Evidence describing spatio-temporal characteristics and associated geographical dispersion gradients was limited. The most commonly tested sample type was dust which also yielded the highest bacterial loads of >10⁸ bacteria/cloth. The MD8 (Sartorius) air sampler was used widely for air sampling. Soil was the only sample type for which a validated laboratory protocol was established specifically for C. burnetii. Each environmental sample type has its advantages and limitations which are discussed in detail and a simplified framework to guide decisions around environmental sampling for C. burnetii is provided. In any type of environmental sampling, it is recommended to use standardized and validated methods and to match the most ideal sampling strategy and timing with the research context. These conditions are essential to be considered when designing future Q fever management plans that involve environmental sampling for C. burnetii.

Molecular Detection of Coxiella burnetii in Cattle on Ulleung Island, Korea: A Population-based Study with Four Years of Follow Up

In a population-based study with 4 years of follow up, we evaluated the prevalence of Coxiella burnetii in cattle on Ulleung Island, Korea. In this study, the rates of C. burnetii infection in cattle on Ulleung Island were determined by PCR and were found to be 0.3-1.0% in the period 2011-2014. All 17 C. burnetii partial 16S rRNA gene sequences from PCR-positive cattle were identical and 2 geographic representatives were included in our analysis. The nucleotide sequences of the 2 samples showed high (98.4-100%) identity with C. burnetii sequences obtained from the GenBank. In this long-term tracking study, the number of cattle positive for C. burnetii on Ulleung Island was low. To prevent the transmission of C. burnetii on Ulleung Island, control strategy should include biosecurity improvement in surveillance, livestock management, administering suitable tests before purchasing animals to detect C. burnetii shedders, and restricting movements between herds.

Herd prevalence and genotypes of Coxiella burnetii in dairy cattle bulk tank milk in Gyeongsang provinces of South Korea

Coxiella burnetii is the causative agent of the zoonotic Q fever, and its reservoirs include ticks and livestock, which are key sources of transmission to humans. Although there have been several studies on the prevalence of C. burnetii antibodies in dairy cattle bulk tank milk (BTM), there is a lack of information on the molecular detection of C. burnetii in BTM in South Korea. Thus, this study was designed to assess milk shedding of C. burnetii in BTM from dairy cattle herds. Among the 607 BTM samples collected from 41 counties in Gyeongsang provinces in 2015, 108 (17.8%) from 23 (56.1%) counties tested positive for C. burnetii by PCR. Because the 16S rRNA sequences of C. burnetii from all 108 PCR-positive samples were identical, two representative samples (BTM-GB-10 and BTM-GN-63) are described in this paper. These sequences showed high identity (96.9-100%) to other C. burnetii sequences deposited in GenBank. Phylogenetic analysis showed that these two sequences were clustered with existing C. burnetii strains. The relatively high prevalence rates of C. burnetii in BTM detected in this study suggest that C. burnetii is prevalent among dairy cattle herds in South Korea. Thus, implementation of continuous monitoring and control strategies for domestic animals is needed to prevent disease transmission and protect public health.

Prevalence and Risk Factors of Coxiella burnetii Antibodies in Bulk Milk from Cattle, Sheep, and Goats in Jordan

This large-scale cross-sectional study was conducted to determine the prevalence, geographical distribution, and risk factors for the presence of antibodies against Coxiella burnetii in bulk tank milk derived from dairy cattle, sheep, and goats in Jordan. Bulk milk samples were collected from 78 dairy cattle, 48 sheep, and 23 goat farms from various places in Jordan according to the density of these animal species in each region of the country. The samples were tested for C. burnetii antibodies using the CHEKIT Q-Fever Antibody ELISA kit. A standardized questionnaire was also used to collect data from each farm to identify and rank the risk factors for the presence of C. burnetii antibodies. The results revealed that 62.9% (95% confidence interval: 55.1 to 70.0%) of the tested ruminant farms were positive for C. burnetii antibodies. Positive results were obtained from 70.9% (60.6 to 79.5%) of dairy cattle farms, 52.1% (38.3 to 65.5%) of sheep farms, and 56.0% (37.1 to 73.3%) of goat farms. Six factors were associated with the presence of these antibodies on cattle farms, and five factors were associated with these antibodies on sheep and goat farms (chi-square test). The multivariate logistic regression model revealed that large dairy cattle farms, farms that add new animals to the herd, farms that infrequently clean the feeders, and farms in particular areas are 28.6, 19.9, 8.0, and 6.4 times more likely, respectively, to have animals with C. burnetii antibodies. Sheep and goat farms that mix their animals with those from other farms, graze more than 5 km, and infrequently sanitize the feeders were 8.0, 0.06, and 13.6 times more likely, respectively, to have animals with C. burnetii antibodies. These data reveal the widespread exposure of Jordanian ruminants to C. burnetii and suggest a high risk for public health.