Extensively drug resistant tuberculosis: Beware patients lost to follow-up

EDITOR—Lawn and Wilkinson report on the global emergence of extensively drug resistant tuberculosis.1 An outbreak of extensively drug resistant tuberculosis has been ongoing for a decade in Norway.2 In 1994 treatment was started in a patient with pulmonary tuberculosis who was lost to follow-up. One year later, the same patient was admitted to hospital with smear positive, pulmonary, extensively drug resistant tuberculosis.2 In the following 10 years, 23 other patients were diagnosed with a strain of Mycobacterium tuberculosis that carried the same IS6110 RFLP and spoligotyping DNA patterns. Of these, 15 had extensively drug resistant tuberculosis (table). Among 3131 patients diagnosed with tuberculosis in Nor-way during these 12 years M tuberculosis was isolated from 2284. Multidrug resistant tuberculosis was identified in 37 of them. The 15 cases of extensively drug resistant tuberculosis in the current outbreak are 0.66% of all culture positive cases and 40% of the multidrug resistant cases diagnosed in the country during 1994-2005.

This outbreak in a country with a low incidence and a well functioning tuberculosis control programme shows the long-lasting effect that one case lost to follow-up may have on the public health of a country. Such effects may lead to disasters in countries with a high incidence, where patients are commonly lost to follow-up.