Moore et al. BMC Public Health 2010, 10:612 http://www.biomedcentral.com/1471-2458/10/612 NTM infection in AIDS patients [6], but cervical lymph node disease in young children and pulmonary disease mimicking tuberculosis in COPD patients. M. kansasii is also commonly associated with pulmonary infections clo- sely resembling tuberculosis, both clinically and radiolo- gically, and may be misdiagnosed [7]. M. malmoense may be clinically significant regardless of the site of infection [8] which is usually pulmonary, again mimicking tuber- culosis, as does M. xenopi. M. abscessus has been described as a prevalent NTM infection in children with cystic fibrosis [9]. M. gordonae is normally considered non-pathogenic and is often found as a laboratory con- taminant but does sometimes cause disease, even in immunocompetent patients [10]. The most recent study of national surveillance data for England and Wales by Lamden et al. reported an increase in NTM reports from 123 in 1982 to 392 in 1994 [11]. Most of this increase was attributed to an increase in M. avium-intracellulare infections, notably in the form of disseminated disease and in males aged 25 to 44 years. Other NTM infections in this study were most com- monly reported in those aged 45 and over. Prior to the increases in HIV infection and AIDS, most NTM infec- tions were found in those aged 50-59 with pre-existing lung conditions or occupational exposure to dusts [12]. Several reports from other western countries have suggested the incidence of NTM disease is increasing [12-14] but there is currently a lack of routine, national surveillance based evidence to support this [12]. The number at risk of NTM infection due to immune-sup- pression is rising owing to factors such as more HIV diagnoses, new treatments for pre-existing conditions such as cystic fibrosis and malignancies, and an increas- ingly elderly population with significant levels of COPD and structural lung disease. This study investigated recent trends in, and described the epidemiology of, NTM infections in England, Wales and Northern Ireland between 1995 and 2006. Methods Hospital laboratories in England, Wales and Northern Ireland voluntarily report mycobacterial infections, as part of routine reporting of all infectious agents, to the Health Protection Agency (HPA) Centre for Infections. Patient samples identified by local hospital laboratories as positive for mycobacteria are forwarded to specialist reference laboratories that will identify the species and report back to the local laboratory. All isolates deemed clinically signif- icant by the source hospital are reported to the HPA. Details routinely reported include age and sex of the patient, species, specimen type and source laboratory. All reports of NTM between 1995 and 2006 were analysed. Incidence rates and percentage change were calculated for each species of NTM reported. Demographic Page 2 of 6 information was analysed for all NTM as a whole, with further detailed analyses for the three most commonly reported species and the species showing the biggest percentage increase over the study period. Clinical infor- mation in comments fields was also reviewed for these species to assess the clinical significance of reports and consider associated risk factors for infection. Office for National Statistics mid-year population esti- mates were used for the calculation of rates of NTM infection per 100,000 population. Analyses by region were completed based on the region of the reporting source laboratory. Site of disease was inferred from spe- cimen type; as in some cases NTM were isolated from more than one site, the total number of reports by site may exceed the total numbers reported otherwise. The Health Protection Agency has Patient Information Advisory Group approval to hold and analyse national surveillance data for public health purposes under Sec- tion 60 of the Health and Social Care Act 2001. Results The rate of all NTM reports increased from 0.9 per 100,000 population in 1995 to 2.9 per 100,000 in 2006 (Table 1). Except from 2002 to 2003, numbers increased annually, rising to 1608 reports in 2006, a 250% increase compared to 1995. The most commonly reported spe- cies was M. avium-intracellulare, accounting for 43% of all reports, followed by M. malmoense (14%) and M. kansasii (13%); M. gordonae showed the biggest percen- tage increase in reports over the study period. Changes in rates for these four species are shown in Figure 1. M. abscessus was not reported prior to 2000, M. peregrinum was not reported before 2004, and an increasing number of isolates were reported without a species name. Most NTM reports were in males (6518/10863, 60%) and the rate of reports was consistently higher each year in males compared to females (3.3 v 2.4 per 100,000 popu- lation in 2006). The majority of reports were from people aged 60 years or over (5717/10824, 53%). The greatest numbers of reports were from the North East (2126/ 11039, 19%) and London (1972/11039, 18%); the highest rate of reports in 2006 was from the North East (10.3 per 100,000) followed by Northern Ireland and London (4.9 and 4.4 per 100,000 respectively). The biggest increases in reports from 1995 to 2006 were in Northern Ireland (1129%) and the North East (1100%). Eighty-one percent (8832/10895) of reports were from a pulmonary site. How- ever, this varied with age: in those aged under 15, 83% (423/507) of reports were extra-pulmonary. M. avium-intracellulare The rate of reports of M. avium-intracellulare rose three-fold from 0.4 per 100,000 in 1995 to 1.2 per 100,000 in 2006 (Table 1, Figure 1). Increases were seen