Seasonal variation among tuberculosis suspects in four countries

Mabaera, Biggie; Naranbat, Nymadawa; Katamba, Achilles; Laticevschi, Dumitru; Lauritsen, Jens M.; Rieder, Hans L.

doi:10.1016/j.inhe.2009.06.006

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Volume 1, Issue 1 , Pages 53-60, September 2009

Seasonal variation among tuberculosis suspects in four countries

Biggie Mabaera
- University of Zimbabwe, P.O. Box A178, Avondale, Harare, Zimbabwe
- University Research Co. (URC), P.O. Box 11975, Maseru, Lesotho.
- Corresponding author. Tel.: +266 22312700; fax: +266 22326117.
Nymadawa Naranbat
- National Centre for Communicable Diseases, Ministry of Health, Nam-Yan-Ju Street, Ulaanbaatar- 210648, Mongolia
- 17/1 Ramsgate Street, Glenelg south, SA-5045, Australia.
Achilles Katamba
- Kampala City Council, Public Health Department, P.O. Box 21696, Kampala, Uganda
- International Union Against Tuberculosis and Lung Disease, 68 boulevard Saint Michel, 75006 Paris – France.
Dumitru Laticevschi
- Tuberculosis/AIDS Project Coordination Unit, 20 Sciusev str. MD2020, Chisinau, Republic of Moldova
- Rue de Zurich 38, CH1201 Geneva, Switzerland.
Jens M. Lauritsen
- Institute of Public Health, Dpt. Biostatistics. University of Southern Denmark, J.B.Winsløwsvej 9b, DK5000 Odense C, Denmark
Hans L. Rieder
- International Union Against Tuberculosis and Lung Disease, 68 boulevard Saint Michel, 75006 Paris – France

Received 9 June 2009; accepted 22 June 2009.

Summary

The objective of the study was to analyze monthly trends across a calendar year in tuberculosis suspects and sputum smear-positive cases based on nationally representative samples of tuberculosis laboratory registers from Moldova, Mongolia, Uganda and Zimbabwe. Out of the 47140 suspects registered in the tuberculosis laboratory registers, 13.4% (6312) were cases. The proportion varied from country to country, Moldova having the lowest (9%) and Uganda the highest (21%). From the monthly proportion of suspects and cases among total suspects and cases, seasonal variations were most marked in Mongolia which, among the four countries, also has the most pronounced seasonal variation in ambient temperature. Female suspects were consistently older than female cases in all four countries. Among males, male suspects were almost consistently older than male cases, most consistently in Moldova. Seasons seem to affect attendance to diagnostic laboratory services, evidenced by the contrasting findings of Mongolia (extreme continental northern climate) compared to Uganda (equatorial climate). A combination of external and possibly endogenous factors seems to determine whether tuberculosis suspects and cases present themselves to health care facilities.