Risk Factors for Mycobacterium Tuberculosis Infection among Children in Greenland/Facteurs De Risque D'une Infection a Mycobacterium Tuberculosis Chez Les Enfants Au Groenland/Factores De Riesgo De la Infeccion per Mycobacterium Tuberculosis En Ninos De Groenlandia

Article excerpt

Introduction

Although Greenland has experienced steady improvement in general living standards since World War II, tuberculosis (TB) remains a major health problem throughout the country. (1,2) Overall TB incidence in Greenland doubled in the 1990s (3) and still remained at 130 cases per 100 000 in 2010. (1) The proportion of TB cases comprised of children under the age of 15 years rose from 8% in 1990 to 25% in 1997. (3) Because of this resurgence of TB, in 1999 national health authorities launched a TB control programme consisting of the vaccination of all neonates with bacille Calmette-Guerin (BCG), early case detection and the monitoring of treatment outcomes. (4) In 2007 the programme was revised to include routine screening of children for Mycobacterium tuberculosis infection (MTI) at the ages of 6 and 16 years. Despite this effort, TB incidence and the risk of MTI among children remain high. (4,5) Surprisingly, the resurgence of TB in Greenland is not linked to human immunodeficiency virus (HIV) infection or to multidrug resistant TB, both of which are still very uncommon in the country. As of 2010, only 157 HIV-positive cases had been registered despite free HIV testing and only one case of multidrug resistant TB had been documented. (1,6) Instead, it appears to result from microepidemic outbreaks in small towns and remote settlements. TB is 20 times more common among the Inuits of Arctic Canada and Alaska than among non-native white populations.(7-11) This elevated risk suggests that even in resource-rich countries, TB control is difficult in small, hard-to-reach communities with limited health resources.

In 2009, a World Health Organization group proposed a revision of current TB control, targeting strategies to minimize exposure to TB as measured by the presence of MTI. (12) The revision raises the need to better understand the risk factors associated with MTI, especially at the local and regional level, since risk factor profiles vary from place to place and one programme will not necessarily be effective everywhere. The objective of this study was to explore the risk factors for MTI among Greenlandic children to help identify the children at highest risk of infection.

Methods

Study sites and population

An ice cap covers 82% of Greenland's territory, permitting settlements only in coastal areas. The population, which numbers 57 000, is 90% Inuit. Greenland is an integral part of the Kingdom of Denmark but is self-governing. Although its population is less affluent than that of Denmark, it is nonetheless wealthy by developing country standards, with a gross national product per capita of 20 000 United States dollars. Health care is provided by the government at Danish standards. (13) The capital, Nuuk, has one national hospital; a local hospital exists in each of the country's five administrative districts, along with additional health centres and nursing stations or clinics. Care is free of charge. However, inequities have not been fully eradicated mainly because small and isolated communities have limited health-care resources and the least experienced health-care workers. (14) Physicians, typically from Denmark, have difficulty communicating with the Inuit population and are usually on short-term assignments, so that gaps between postings sometimes occur. Living in a small community is an independent risk factor for TB disease. (15)

The current study, cross-sectional in design, included all schoolchildren in five different towns and nearby settlements across Greenland: Tasiilaq (November, 2005) in eastern Greenland; Narsaq (May, 2006), Qaqortoq (August, 2006) and Nanortalik (September 2006) in southern Greenland; and Sisimiut (May, 2007), in western Greenland. School attendance is mandatory everywhere in the country for children aged from 6 to 16 years. On 31 December 2006, the study area had 2880 eligible children in that age group (i.e., 25% of the entire Greenlandic population of children 6 to 16 years old), all of whom were invited to participate in the study. …