A super-spreading ewe infects hundreds with Q fever at a farmers' market in Germany
2006

Q Fever Outbreak Linked to a Farmers' Market in Germany

Sample size: 299 publication 10 minutes Evidence: high

Author Information

Author(s): Porten Klaudia, Rissland Jürgen, Tigges Almira, Broll Susanne, Hopp Wilfried, Lunemann Mechthild, van Treeck Ulrich, Kimmig Peter, Brockmann Stefan O, Wagner-Wiening Christiane, Hellenbrand Wiebke, Buchholz Udo

Primary Institution: Robert Koch-Institute

Hypothesis

Is there a link between the farmers' market and the outbreak of Q fever?

Conclusion

The outbreak was linked to a single infected ewe at the farmers' market, leading to significant public health recommendations.

Supporting Evidence

  • 299 cases of Q fever were linked to the farmers' market outbreak.
  • The mean incubation period for the disease was 21 days.
  • 25% of the reported cases were hospitalized.
  • Close proximity to the sheep pen was identified as a significant risk factor.
  • Wind direction did not significantly affect the spread of the disease.
  • 65% of serum samples tested positive for Q fever antibodies.
  • 85% of cases reported having spent time near the sheep pen.
  • Clinical attack rates were estimated at 20% for adults and 3% for children.

Takeaway

A sick sheep at a market made a lot of people sick with Q fever, so now we need to be careful about showing pregnant sheep in public.

Methodology

The study involved case control and cohort studies to identify risk factors and confirm the outbreak source.

Potential Biases

Potential recall bias in reporting attendance at the market.

Limitations

The study relied on self-reported data and may have underreported cases.

Participant Demographics

The mean age of cases was 54 years, with a gender distribution of 53% male and 47% female.

Statistical Information

P-Value

<0.001

Confidence Interval

95% CI = 22 – 3601

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1186/1471-2334-6-147

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