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Q Fever Dairy Herd Status Determination Based on Serological and Molecular Analysis of Bulk Tank Milk
Author(s) -
Anastácio S.,
Carolino N.,
SidiBoumedine K.,
Silva G. J.
Publication year - 2016
Publication title -
transboundary and emerging diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.392
H-Index - 63
eISSN - 1865-1682
pISSN - 1865-1674
DOI - 10.1111/tbed.12275
Subject(s) - coxiella burnetii , herd , q fever , seroprevalence , bulk tank , serology , veterinary medicine , biology , abortion , dairy cattle , zoology , ruminant , antibody , pregnancy , medicine , immunology , virology , pasture , ecology , genetics
Summary Ruminants are recognized as the main reservoirs of Coxiella burnetii . EFSA highlighted the lack of knowledge about Q fever prevalence in many European countries. A cross‐sectional study was carried out in randomly selected dairy herds ( n = 109) from central Portugal to screen for C. burnetii infection and to correlate it with herd factors. Bulk tank milk ( BTM ) samples from cattle ( n = 45) and small ruminant ( n = 64) herds were tested by ELISA and PCR . The apparent seroprevalence of Q fever was estimated in 45.9% (95% CI: 36.3–55.7) being higher in small ruminants (51.6; 95% CI: 39.6–63.4) than in cattle (37.8; 95% CI: 25.1–52.4). The shedding of C. burnetii in BTM was detected in 11.9% (95% CI: 7.1–19.4) of BTM , and it was higher in cattle (20%; 95% CI: 10.9–33.8) than in sheep and mixed herds (6.3%; 95% CI: 2.5–15). A high bacterial load (≥ 3 × 10 3 bacteria/ml) was observed in 85% of PCR ‐positive BTM . A significant correlation was found between the bacterial load and positive samples on ELISA ( P < 0.001). Antibody positivity was significantly associated with the increased herd size ( P < 0.01) and the occurrence of abortion ( P < 0.05), whereas the shedding of C. burnetii was significantly associated with the report of infertility ( P < 0.05). The results highlight that serological and molecular methods in combination are a useful tool to screen for Q fever and to clarify the herd infection status. The shedding of C. burnetii through milk is important, especially in dairy cattle, and thus, the role of milk as a potential source of infection among dairy workers should not be neglected. To our knowledge, this is the first study reporting C. burnetii infection in dairy livestock in Portugal showing that Q fever is significant in dairy herds, leading to economic losses and being a risk for public health, which highlights the need of implementation of control measures.