Risk factors for contracting plague in Nkayi district, Zimbabwe.

OBJECTIVE

To identify risk factors for contracting plague among the three to 16 year old age group.

DESIGN

A matched case control study, carried out in two parts.

SETTING

Nkayi District--a plague endemic area in Zimbabwe.

SUBJECTS: A total of 86 cases were randomly selected from a line listing of all reported plague cases in the district. Two neighbourhood controls were selected from households at least 500 m on either side of the case household.

MAIN OUTCOME MEASURES: Maximum likelihood estimate of the odds ratio (OR) for the 17 risk factors studied (grouped as personal, environmental, domestic animals and rat reports).

RESULTS

Risk factors which were significantly associated with contracting plague were having a sick cat in the household (OR 3.4, 95% CI 1.1 to 13.0), herding cattle (OR 1.7, 95% CI 1.0 to 3.0), and age 10 years or older (OR 2.2, 95% CI 1.2 to 4.1). In a logistic model, only having a sick cat was found to be independently associated with being a case (OR 3.9, 95% CI 1.3 to 12.2).

CONCLUSION

The presence of a sick domestic cat was identified as a risk factor for acquiring bubonic plague during this outbreak. Communities should be informed that sick cats may act as a warning of potential plague, and that if cats become sick they should be removed from the household.