Table 1.

Characteristics and main results of the eligible studies ordered by molecular prevalence of Coxiella burnetii in bulk-tank milk samples.

Author	Year	Country	Study area	Average herd size	Period of study	Risk factor analysis	Gross national income per capita [38]	Is Q fever a mandatory notifiable disease?	Molecular approach	Target gene	N herds in study area	Percentage of herds sampled	BTM(i) samples tested	Positive BTM samples	Prevalence	95% CI
Boroduske et al. [43]	2017	Latvia	Nationwide	8.6	2015	Yes	High-income	Yes	qPCR	IS1111	5040	5	252	27	10.7	7.2	14.9
Kargar et al. [23]	2013	Iran	Johrom	3.7	–	Yes	Upper-middle-income	Yes	nPCR	com1	3000	3.3	100	11	11	5.5	18.0
Seo et al. [44]	2018	South Korea	Gyeongsang	74	2015	No	High-income	Yes	nPCR	16S rRNA	869	69.9	607	108	17.8	14.8	20.9
Rahimi et al. [45]	2010	Iran	Chaharmahal and Bakhtiari	48	2008	No	Upper-middle-income	Yes	nPCR	com1	95	29.5	28	5	17.9	5.5	34.5
van Engelen et al. [46]	2014	Netherlands	Nationwide	71.7	2009–2011	Yes	High-income	Yes	qPCR	IS1111	20,746	1.5	309	58	18.8	14.6	23.3
Anastácio et al. [47]	2016	Portugal	Nationwide	21.7	2009–2013	Yes	High-income	No	PCR	IS1111	1712	2.6	45	9	20	10.9	33.8
Velasova et al. [48]	2017	UK	Nationwide	133	2014–2015	No	High-income	No	qPCR	icd/IS1111	10,491	2.1	220	57	25.9	20.3	31.9
Czaplicki et al. [49]	2012	Belgium	Wallonia	28.5	2006	Yes	High-income	No	qPCR	IS1111	5086	1	50	15	30	8.7	51.3
Magnino et al. [50]	2009	Italy	Cremona, Montova and Pavia	180	2007–2008	No	High-income	No	PCR	IS1111	3550	11.2	400	161	40.2	35.5	45.1
Valla et al. [51]	2014	Italy	Nationwide	42.5	2011–2013	No	High-income	No	PCR	IS1111	30,000	1.1	344	138	40.1	35.0	45.4
Contreras et al. [37]	2015	Colombia	Monteria	150–600	2012	No	Upper-middle-income	No	PCR	IS1111	3341	0.3	11	5	45.5	16.7	75.8
Astobiza et al. [52]	2012	Spain	Bizkaia	46.1	2009–2010	No	High-income	No / Yes(ii)	qPCR	IS1111	178	100	178	92	51.7	44.4	59
Muskens et al. [25]	2011	Netherlands	Nationwide	65.7	2007	No	High-income	Yes	qPCR	IS1111	21,313	1.6	341	193	56.6	50.7	61.9
Vicari et al. [34]	2013	Italy	Lombardy	182	2011	No	High-income	No	PCR	IS1111	5750	5	287	173	60.3	54.5	65.9
Bauer et al. [53]	2015	USA	Indiana	145.3	2011	No	High-income	Yes	qPCR	IS1111	1225	25.8	316	193	61.1	55.6	66.4
Gyuranecz et al. [54]	2012	Hungary	Nationwide	14.5	2010–2011	No	High-income	Yes	qPCR	IS1111	17,172	0.1	15	10	66.7	40.5	88.7
APHIS [55]	2007	USA	18 states(iii)	162.6	2007	No	High-income	Yes	qPCR	IS1111	54,100	1	528	406	76.9	73.2	80.4

(i): BTM: bulk-tank milk samples, one per herd; PCR: conventional PCR; qPCR: real-time PCR; nPCR: nested PCR. (ii) mandatory notification in Basque Country. (iii) California, Idaho, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, New Mexico, New York, Ohio, Pennsylvania, Texas, Vermont, Virginia, Washington, Wisconsin.