A Q Fever Outbreak with a High Rate of Abortions at a Dairy Goat Farm: Coxiella burnetii Shedding, Environmental Contamination, and Viability

• Published in: Applied and environmental microbiology Vol. 84; no. 20
• Main Authors: Álvarez-Alonso, Raquel, Basterretxea, Mikel, Barandika, Jesús F, Hurtado, Ana, Idiazabal, Jasone, Jado, Isabel, Beraza, Xabier, Montes, Milagros, Liendo, Paloma, García-Pérez, Ana L
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 01.10.2018
• Subjects: Abortion; Aerosols; Agricultural pollution; Alpine environments; Arthralgia; Bacteria; Caprinae; Cell culture; Contamination; Coxiella burnetii; Dairy farms; Deoxyribonucleic acid; DNA; Dust; Dust control; Environmental monitoring; Epidemics; Excretion; Farms; Feces; Food contamination; Genotypes; Goats; Inoculation; Mucus; Myalgia; Outbreaks; Parturition; Public and Environmental Health Microbiology; Q fever; Seroconversion; Shedding; Vagina; Vero cells; Viability; Workers; SNP; Coxiella burnetii; dust; goats; MST; viability
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.01650-18

This study describes a Q fever outbreak in a herd of 77 Alpine goats which suffered a high rate of abortions (81% [58/72]) in January 2017 and presents the results of monitoring the contamination and viability of in the farm environment several months after the outbreak. Over the course of 7 months, we studied bacterial shedding by 35 dams with abortions to monitor infection dynamics and the duration of excretion. The highest bacterial shedding load was observed in vaginal mucus, followed by in feces and in milk. Conversely, the duration of shedding was longer through feces (5 months after abortion) than milk (3 months). DNA was detected throughout the study in aerosol samples periodically collected indoors and outdoors from the animal premises. Mouse inoculation and culture in Vero cells demonstrated the presence of viable isolates in dust collected from different surfaces inside the animal facilities during the period of time with the highest number of abortions but not in dust collected 2, 3, and 4 months after the last parturition. Some workers and visitors were affected by Q fever, with attack rates of 78% (7/9) and 31% (4/13), respectively. Affected people mostly showed fever and seroconversion, along with myalgia and arthralgia in two patients and pneumonia in the index case. The genotype identified in animal and environmental samples (SNP1/MST13) turned out to be very aggressive in goats but caused only moderate symptoms in people. After the diagnosis of abortion by Q fever in goats, several control measures were implemented at the farm to prevent contamination inside and outside the animal facilities. This work describes a 7-month follow-up of the excretion by different routes of genotype SNP1/MST13 in a herd of goats that suffered high rate of abortions (81%), generating high environmental contamination. Some of the workers and visitors who accessed the farm were infected, with fever as the main symptom but a low incidence of pneumonia. The detected strain (SNP1/MST13 genotype) turned out to be very aggressive in goats. The viability of was demonstrated in the environment of the farm at the time of abortions, but 2 months after the last parturition, no viable bacteria were detected. These results highlighted the importance of implementing good biosafety measures at farms and avoiding the entrance of visitors to farms several months after the end of the kidding period.