Infectious Disease in Arctic Population Infectious Disease in Arctic Population
Centers for Disease Control and Prevention
Life at the top of the globe is drastically different. An often-harsh climate devoid of sunlight part of the year, pockets of extreme poverty and a lack of physical infrastructure interfere with healthcare and public health services. To help address the challenge, the Centers for Disease Control and Prevention has joined forces with health officials from Canada, Greenland, Iceland, Finland, Norway, Denmark and Sweden to study the unique aspects of public health in the circumpolar region. Since 1998, CDC and the other organizations in the International Circumpolar Surveillance Working Group have collaborated on health studies that address a variety of health topics, including pneumococcal disease, tuberculosis, viral hepatitis and Haemophilus influenzae type b infections. Some recent studies are presented in the January 2008 edition of CDC’s journal, Emerging Infectious Diseases, which dedicates the issue to the International Polar Year and infectious diseases in Arctic populations.
The issue includes an article on the impact of invasive pneumococcal disease in the Arctic region, including on Alaska Native children. A summary of the article follows.
Surveillance of Invasive Pneumococcal Disease in the Arctic
Emerging Infectious Diseases, Volume 14, Number 1–January 2008, International Polar Year
For years, rates of invasive pneumococcal disease, a sometimes fatal bacterial disease that causes pneumonia and meningitis, have been higher in Alaska Natives than in nonindigenous Alaskans. Children less than age 2 have been particularly hard-hit, with rates of disease 4 to 6 times higher than their non-Native peers.
In the first population-based assessment of the disease in the Arctic using similar methods, scientists from CDC and from institutions in other circumpolar nations analyzed invasive pneumoccocal disease data by country to determine rates of disease, risk factors and disease trends following the introduction of a pneumococcal vaccine called PCV7.
The study found that, during 1999–2005, more than 11,000 cases of invasive pneumococcal disease were detected among the 7 circumpolar areas of study (Alaska, Canada, Norway, Iceland, Greenland, Finland and Sweden). Rates were highest in young children and in the elderly.
After vaccination with PCV7 began, rates of disease caused by the strains included in the vaccine decreased dramatically in children less than age 2 in Alaska and northern Canada, from about 128 cases per 100,000 to 15–20 per 100,000 population. The study also showed a general decrease in cases of invasive pneumococcal disease caused by the vaccine strains in older children and adults, who did not receive the vaccine. Typically, children are the primary carriers of the bacteria. Vaccinating them prevents transmission, even to those who haven’t been vaccinated.
However, many challenges remain. Rates of this disease remain high in Alaska Native children, highlighting a persistent health disparity in this group. And in recent years, experts have seen disease rates of those strains not used in the vaccine more than double. In fact, before the vaccine’s introduction, more than 80 percent of the infections in children less than age 2 in Alaska were caused by the strains used in the vaccine. After the vaccine was introduced, those same strains accounted for only about 20 percent of disease. The rise in non-vaccine type disease in rural Alaska is concerning.
Future health efforts should address conditions that lead to higher rates of respiratory diseases; these conditions include crowded housing, lack of running water and sanitation facilities, tobacco use and other factors. A new vaccine currently under evaluation in the United States contains strains that have emerged in recent years in the Arctic and may succeed in preventing most cases among children.