[The epidemiology of Q fever in the northern area of Huelva, Spain].

OBJECTIVE

The aim of the present study is to know the prevalence, incidence and clinical presentation of the acute Q fever in the north of the Huelva district.

METHODOLOGY

a) Prevalence: 1,654 serum were randomly collected from the health district and distributed by their origin, age and sex. The methodology used was the indirect immunofluorescence, Coxiella burnetii phase II as antigen. Were regarded as positives those serum whose titles were equal or higher to 80; b) Incidence: prospective study of every case treated in hospital during 1996-1997 plus every referred patient from the different "Health Centers". An acute case of Q fever was established as a feverish syndrome of more than 2 days plus a title equal or higher to 320 against C. burnetti phase II antigen, and c) Clinical data: all the patients were clerked and similar form was filled up including the following items: pneumonia, hepatitis, headache, persistent fever, etc.

RESULTS

a) Prevalence: it was 5.08%, more frequent in men than in women; b) Incidence: 21 new cases over two years, an incidence of 12.70 cases per 100,000 population, and c)

CLINICAL PRESENTATION

feverish syndrome plus hepatitis in 100% of the cases, just two pneumonia were recorded and in 4 cases the clinical picture was associated to immunological symptoms with persistent fever.

CONCLUSION

A discrepancy between incidence and prevalence has been pointed out which makes us think that the majority of the Q fever cases in this area debut as a self restricted feverish syndrome which does not require specialized treatment.