[Epidemiology of non-tuberculous mycobacteriosis (NTM) in Japan]

Abstract

An epidemiologic study of NTM was conducted by the Mycobacteriosis Research Group of the Japanese National Chest Hospital. The case cards of patients with NTM disease from 97 sanatoriums were studied. The total number of NTM patients newly admitted to these sanatoriums was 3,057 in the 8 years from 1985 to 1992. The number of NTM patients increased each year, and the prevalence was estimated at 2.99 per 10(5) population in 1992, which was double what it had been in 1985. In contrast, the rate of tuberculosis (Tbc) announced officially by the Ministry of Public Welfare was 15.2 (the rate was almost unchanged over the 8 years from 1985 to 1992). A total of 3,731 patients were supposed to be newly afflicted with NTM in 1992, and they accounted for 16% of all bacilli-positive patients infected with acid-fast bacilli. Of all NTM patients, 80% were infected with Mycobacterium avium Complex (MAC) and 10% were infected with M. kanaasii. In MAC cases, M. avium was predominant in the northern half of Japan (from Kinki to Hokkaido) and M. intracellulare was predominant in the southern half (from Chugoku to Kyushu). Of all the MAC patients, 52.7% female, the average age was 68 years, and in 52.3% of these patients the MAC infection accompanied other diseases such as bronchiectasis. Of the patients with M. kansasii, 92.7% were male, the average age was 53 years, and only 32.5% of the patients had other diseases. To obtain treatment with anti-tuberculosis drugs at public expense, many patients with NTM may be registered officially as Tbc patients.(ABSTRACT TRUNCATED AT 250 WORDS)