Epidemiology and Infection

Original Papers

Tularaemia, typhus, and malaria

Risk factors for pneumonic and ulceroglandular tularaemia in Finland: a population-based case-control study

H. ROSSOWa1a2, J. OLLGRENa3, P. KLEMETSa3, I. PIETARINENa4, J. SAIKKUa5, E. PEKKANENa3, S. NIKKARIa2, H. SYRJÄLÄa6, M. KUUSIa3 and J. P. NUORTIa3a7 c1

a1 Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, Helsinki, Finland

a2 Centre for Biothreat Preparedness, CB Defence and Environmental Health Centre, Finnish Defence Forces, Helsinki, Finland

a3 Department of Infectious Disease Surveillance and Control, National Institute for Health and Welfare (THL), Helsinki, Finland

a4 Occupational Healthcare Services, Terveystalo Oulu, Oulu, Finland

a5 Etelä-Pohjanmaa Central Hospital, Seinäjoki, Finland

a6 Oulu University Hospital, Oulu, Finland

a7 School of Health Sciences, University of Tampere, Finland

SUMMARY

Few population-based data are available on factors associated with pneumonic and ulceroglandular type B tularaemia. We conducted a case-control study during a large epidemic in 2000. Laboratory-confirmed case patients were identified through active surveillance and matched control subjects (age, sex, residency) from the national population information system. Data were collected using a self-administered questionnaire. A conditional logistic regression model addressing missing data with Bayesian full-likelihood modelling included 227 case patients and 415 control subjects; reported mosquito bites [adjusted odds ratio (aOR) 9·2, 95% confidence interval (CI) 4·4–22, population-attributable risk (PAR) 82%] and farming activities (aOR 4·3, 95% CI 2·5–7·2, PAR 32%) were independently associated with ulceroglandular tularaemia, whereas exposure to hay dust (aOR 6·6, 95% CI 1·9–25·4, PAR 48%) was associated with pneumonic tularaemia. Although the bulk of tularaemia type B disease burden is attributable to mosquito bites, risk factors for ulceroglandular and pneumonic forms of tularaemia are different, enabling targeting of prevention efforts accordingly.

(Received June 17 2013)

(Revised October 11 2013)

(Accepted November 02 2013)

(Online publication December 02 2013)

Key words

  • Case-control study;
  • epidemiology;
  • Francisella tularensis ;
  • risk factors;
  • tularaemia

Correspondence

c1 Author for correspondence: Professor J. Pekka Nuorti, Department of Epidemiology, School of Health Sciences, FIN-33014, University of Tampere, Finland. (Email: Pekka.Nuorti@uta.fi)

Footnotes

  This study was presented in part at the Infectious Disease Society of America (IDSA) Annual Meeting, San Francisco, CA, 2001, abstract no. 865; and the 27th International Congress on Occupational Health – ICOH 2003, 23–28 February 2003, Iguassu Falls, Brazil.

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