Coxiella burnetii in bulk tank milk samples from dairy goat and dairy sheep farms in The Netherlands in 2008

Abstract

In 2007, a human Q fever epidemic started, mainly in the south eastern part of The Netherlands with a suspected indirect relation to dairy goats, and, to a lesser degree, to dairy sheep. This article describes the Q fever prevalences in Dutch dairy goat and dairy sheep bulk tank milk (BTM) samples, using a real-time (RT) PCR and ELISA. Results of BTM PCR and ELISA were compared with the serological status of individual animals, and correlations with a history of Q fever abortion were determined. When compared with ELISA results, the optimal cut-off value for the RT-PCR was 100 bacteria/ml. In 2008, there were 392 farms with more than 200 dairy goats, of which 292 submitted a BTM sample. Of these samples, 96 (32.9 per cent) were PCR positive and 87 (29.8 per cent) were ELISA positive. All farms with a history of Q fever abortion (n=17) were ELISA positive, 16 out of 17 were also PCR positive. BTM PCR or ELISA positive farms had significantly higher within-herd seroprevalences than BTM negative farms. In the south eastern provinces, the area where the human Q fever outbreak started in 2007, a significantly larger proportion of the BTM samples was PCR and ELISA positive compared to the rest of The Netherlands. None of the BTM samples from dairy sheep farms (n=16) were PCR positive but three of these farms were ELISA positive. The higher percentage of BTM positive farms in the area where the human Q fever outbreak started, supports the suspected relation between human cases and infected dairy goat farms.

Bulk tank milk surveillance as a measure to detect Coxiella burnetii shedding dairy goat herds in the Netherlands between 2009 and 2014

“…Before the start of the vaccination campaign in 2008, BTM ELISA results showed that 87 (29.8%) out of 292 voluntarily submitted BTM samples from dairy goat farms were serologically positive ( Van den Brom et al, 2012b). Our study shows that within a year after vaccination BTM ELISA results were significantly higher compared with the period before.…”

“…In this retrospective cohort study, 28% of all dairy goat farms tested C. burnetii BTM PCR positive in at least 1 of the first 3 rounds of the surveillance program in 2009. Compared with 2009, a slightly higher proportion of dairy goat farms was BTM PCR positive in 2008 (32.9%; 95% CI = 30.2-35.6), although that prevalence was measured in voluntarily submitted BTM samples from 74.4% of the Dutch dairy goat farms (Van den Brom et al, 2012b). As surveillance programs for C. burnetii based on BTM samples from dairy goat farms are a relatively new phenomenon, only a small number of studies from other countries described results of C. burnetii BTM testing.…”

“…The test was performed according to the manufacturer's instructions and results are presented in 3 classes: negative (<100 bacteria/mL), high positive (≤100 to <10,000 bacteria/mL based on PCR), and very high positive (PCR ≥10,000 bacteria/mL), as proposed by Van den Brom et al (2012b). In October 2009, a surveillance program based on BTM testing became mandatory for all dairy sheep and dairy goat farms with more than 50 animals, and BTM samples were tested twice a month during the lambing season, between December 1 and June 30.…”

“…by C. burnetii, the highest area under the receiver operator curve of the ELISA was at a PCR cutoff of 100 bacteria/mL (Van denBrom et al, 2012b), and this value was used during the BTM surveillance program which started in October 2009.…”

Coxiella burnetii infection in sheep and goats: a public risk health, Colombia

“…In a study performed in Germany, C. burnetii DNA was found in 5% of 39 flock's sheep 27 . In the Netherlands, C. burnetii DNA was detected in 33% of 292 goat farms 28 . In Italy, C. burnetii DNA was amplified in 18% of 199 goats and sheep farms with reproductive history 29 .…”