[Tularemia outbreak in the province of Cuenca associated with crab handling]

Abstract

Objective: To report the clinical and epidemiologic characteristics of 19 patients diagnosed of tularemia at our hospital following an epidemic outbreak occurred in our health area.

Methods: Retrospective analysis of clinical records of patients admitted to our hospital who were examined at the Infectious Diseases Clinic and had clinical findings and epidemiologic data consistent with tularemia during the period from June 1998 to March 1999.

Case definition: A patient was considered to fulfill the case definition when clinical symptoms, epidemiologic data and the following laboratory criteria were met: antibody titer to Francisella tularensis (tube agglutination test) > or = 1/128 in the convalescence serum specimen, seroconversion or recovery of the microorganism from biological material.

Results: Nineteen patients with a median age of 60 years. Males predominated (63.1% male patients); all of them had handled red crayfish from the same source (río Mayor). The incubation period ranged from 0 to 15 days (mean 4.88 days). All patients presented with the ulceroglandular form. Seventy-three percent of patients received doxycycline. Only one patient relapsed. Water samples from the reservoir of the depuration plant of the river were positive to F. tularensis by PCR. This same result was confirmed in stomach and hepatopancreas of crayfish fished in río Mayor in the second half of July.

Conclusions: The most likely hypothesis of this outbreak was the contamination of the river water with animals dead from tularemia which, together with the characteristics of the transmission mechanism (wounds caused by crabs) had contributed to the acquisition of this disease in humans. Interestingly too, red crayfish as the source of infection.