Epidemiology and Clinical Features of Human Infection with Coxiella burnetii in Denmark During 2006–07

Abstract

Query (Q) fever was virtually unknown in Denmark in 2005, when, after the introduction of new sensitive diagnostic methods for Coxiella burnetii, an increasing number of positive cattle created concern among people with frequent exposure. This led to a dramatic rise in examinations for Q fever among humans in the following 2 years. The aim of our study was to assess indication for testing and symptoms in individuals with serological signs of infection with C. burnetii. We performed a case-review study of seropositives among all humans tested for Q fever in 2006-07 in Denmark. Seropositive cases were categorized with acute infection: 4-fold increase in immunoglobulin G (IgG) phase II or concomitant IgM phase II ≥ 1 : 256 and IgG phase II ≥ 1 : 1024; and previous infection: IgG phase II ≥ 1 : 1024. A borderline result was defined as: IgG phase II = 1 : 512. Physicians completed a questionnaire retrospectively. Of the 1613 people tested, 177 (11%) were seropositive [37 (2%) acute infection, 140 (9%) previous infection], 180 had a borderline result. Among 127 seropositives responders, 31% were tested due to symptoms compatible with Q fever after a possible exposure to C. burnetii, 64% were asymptomatic and were tested following relevant exposure only; 64% were males, 43% farmers, 39% veterinarians, 84% had been exposed to cattle. The most frequently reported symptoms were asthenia (25%), myalgia (21%), fever (17%) and headache (13%). About two-thirds of seropositives reported asymptomatic infections, and were tested for Q fever because of concern for occupational exposure to cattle. One-third of the seropositives reported symptoms consistent with Q fever, the majority being mild. Our study provided important evidence that increased requests for Q fever testing in 2006-07 arose from heightened public awareness of the disease, and not from an outbreak of clinical disease. Nonetheless, Q fever should be considered endemic in Denmark.

Adverse Pregnancy Outcomes andCoxiella burnetiiAntibodies in Pregnant Women, Denmark

“…Findings of adverse pregnancy outcome in infected women, high seroprevalence in animal studies, and large human outbreaks have placed increasing focus on Q fever in several European countries, including Denmark ( 1 – 4 ). In ruminants, infection with C. burnetii is associated with high numbers of bacteria in the placenta, and the infection is known to cause abortion, retained placenta, endometritis, and infertility ( 5 , 6 ).…”

“…A recent study of the seroprevalence of C. burnetii in cattle found that bulk-tank milk samples tested positive for C. burnetii at 59 of 100 randomly selected farms ( 16 ). In addition, the reported prevalence of antibodies to C. burnetii among veterinarians in Denmark ranges from 36% to 47% ( 1 , 2 , 17 ). These findings show that exposure to C. burnetii is common in this country in the animal reservoir and in those who are occupationally exposed to livestock or who live in rural areas with livestock contact.…”

Acute Q fever in febrile patients in northwestern of Iran

“…In similar studies, 35.5% in Mali [29], 21.74% in Croatia [30] and 8.7% [27] in Denmark were previously infected with Q fever. In a systematic review conducted in Africa, human seroprevalence was <8% with the exception of studies among children and in Egypt, it was 10–32% [39].…”

“…In similar studies conducted in France, Denmark, Mali and Croatia 2.1% (of 179794), 2.3% (of 1613), 3.9% (of 165) and 5.8% (of 552) of febrile suspected patients were diagnosed to have acute Q fever, respectively [27–30]. The rate of infection in this study was reported much higher than the so-called as in the current study, patients with epidemiological risk factors (having high-risk occupation or living in areas close to livestock or having a history of keeping animals) and clinical risk factors (having a nonspecific febrile illness) were enrolled as the cases and which increased the chance of finding acute Q fever patients.…”

Risk of adverse pregnancy outcome in women exposed to livestock: a study within the Danish National Birth Cohort

“…In pig farmers and veterinarians, exposure to Y. enterocolitica is likely, and individuals working with cattle, sheep, or goats would have a risk of verocytotoxin-producing E. coli or C. burnetii exposure [17,18,30].…”