Chronic Disease caused by
Infectious Agents
Table of Contents
- What chronic diseases are caused by infectious agents?
- Which of these chronic diseases are important in Alaska?
- Current prevention methods and projects
- References
What diseases are caused by infectious agents?
Several chronic diseases once thought due to genetics, lifestyle or environmental factors are now known to be caused or worsened by infectious agents. These include stomach ulcers, chronic liver disease, a chronic lung disease called bronchiectasis and certain types of cancer and arthritis (inflammation of the joints). In the future, some chronic diseases may be treated with antibiotics, prevented by vaccines, or controlled by health education programs that enable susceptible people to avoid disease-causing microbes.
Which of these chronic diseases are important in Alaska?
Duodenal ulcers and stomach cancer- Helicobacter pylori
The discovery of Helicobacter pylori bacteria in most duodenal ulcers has revolutionized medical management of this chronic disease. In most cases, ulcers can be cured following appropriate antibiotic therapy, although the emergence of H. pylori strains that are resistant to antibiotics is making treatment of these infections more difficult. H. pylori are also considered a carcinogen (cancer-causing agent) because of its association with gastric (stomach) cancer; however, the factors which cause certain persons with H. pylori to develop gastric cancer are unclear. Finally, because of chronic gastrointestinal blood loss among persons who are infected, H. pylori may account for the long-observed high rate of anemia despite a diet rich in iron among Alaska Natives.
Chronic liver disease and cancer
Hepatitis B and hepatitis C viruses can result in chronic liver disease and liver cancer. Hepatitis C virus is also associated with a particular type of arthritis, as well as a disease of the blood vessels (vasculitis), cryoglobulinemia (a blood disorder) and peripheral neuropathy (disease resulting in pain, numbness, and altered sensations).
The rate of hepatitis B sequelae has been high among Alaska Natives because of historically high rates of hepatitis B infection. The annual incidence of hepatocellular carcinoma (liver cancer) among Eskimo males was 11.2 cases per 100,000, five times that of white males in the United States. Hepatitis B vaccination has almost completely eliminated new hepatitis B infections among Alaska Natives which should dramatically decrease these sequelae in future years.
Chronic Lung Disease - Bronchiectasis
Bronchiectasis, a debilitating chronic respiratory disease, is associated with certain lower respiratory tract infections. This is a rare condition in the general US population and is seen mainly among patients with cystic fibrosis. However, it is much more commonly diagnosed among Alaska Native children and other indigenous peoples such as Australian Aborigines and Pacific Islanders. In Alaska Natives, the prevalence of bronchiectasis remains 10-20 per 1,000 persons, and recurrent pneumonia in infancy and childhood appears to be the principal risk factor for bronchiectasis.
Current prevention methods and projects
Duodenal ulcers and stomach cancer- Helicobacter pylori
The Arctic Investigations Program and Native corporations have several studies to study H. pylori, including studies of the relationship between H. pylori and childhood anemia, and studies to examine the treatment of H. pylori.
Because of the high rates of gastric cancer in Alaska Natives and its current association with H. pylori infection, the Arctic Investigations Program and Native health corporations are in the process of developing studies to better understand gastric cancer in the Alaska population and determine if it is associated with H. pylori infection in this population. Another goal is to look for factors that may predict which of the many persons with H. pylori infection will go on to develop more severe problems such as ulcers or cancer.
For more information on H. pylori studies and treatment of ulcer disease, see the Helicobacter pylori page.
Chronic liver disease and cancer related to hepatitis B and C
Early identification of hepatocellular carcinoma or active liver disease from
hepatitis B or C can lead to new effective therapies, including anti-viral
therapy and early cancer treatment. The Alaska Native Tribal Health Consortium
Viral Hepatitis Program and Arctic Investigations Program have several projects
to optimize the treatment of persons with sequelae from hepatitis B and C
including:
- A study to test hepatitis B carriers every 6 months for markers that identify early hepatocellular cancer so that these patients can receive early effective treatment.
- A study on the risk factors associated with acquiring hepatitis C infection and the factors associated with progression of liver disease.
- A study to examine hepatitis B carriers for viral and clinical factors associated with progression of liver disease and development of hepatocellular carcinoma.
For more information on current prevention methods and future plans, see the Hepatitis page.
Bronchiectasis related to early childhood pneumonias
Hospitalizations for respiratory infections and Respiratory Syncytial Virus (RSV) in Alaska Natives are among the highest reported for any population. Important modalities for prevention of RSV hospitalization include: encouraging breastfeeding, encouraging hand washing, reducing household crowding, and reducing second hand smoke exposure. In a small group of high-risk infants with prematurity, lung disease or heart disease, monthly injections of the RSV-specific monoclonal antibody palivizumab, is an important measure for preventing RSV hospitalization. Currently, the Arctic Investigations Program and Native health corporations conduct surveillance of RSV activity to provide more information about seasonal RSV epidemics and provide decisions about when to start monthly palivizumab injections. Further development of respiratory surveillance systems is important for evaluating other viruses and bacteria causing hospitalizations, and to evaluate interventions.
Preventing and treating chronic lung problems such as bronchiectasis is a more complex issue that involves preventing recurrent respiratory tract infections. Because of the differences in epidemiology of bronchiectasis for Alaska Natives the standard clinical management model for a person with cystic fibrosis may not be the best approach for optimal clinical care. Physicians from the Arctic Investigations Program and Native corporations are collaborating with physicians treating Australian Aborigines to develop needed clinical evaluations which would define the natural history of bronchiectasis in indigenous children, and to define the role of antibiotics in the prevention of recurrent exacerbations and progression of disease.
For more information see Respiratory Syncytial Virus page.
References:
McMahon BJ, Hennessy TW, Bensler JM, et al. The relationship between prior antimicrobial use, antimicrobial resistance and treatment outcome for Helicobacter pylori infections. Ann Intern Med 2003;6(139):463-69.
Petersen KM, Parkinson AJ, Nobmann ED, Bulkow L, Yip R, Mokdad A. Iron deficiency anemia among Alaska Natives may be due to fecal loss rather than inadequate intake. J Nutr 1996;126:2774-83.
Yip R, Limburg PJ, Ahlquist DA, et al. Pervasive occult gastrointestinal bleeding in an Alaska Native population with prevalent iron deficiency. Role of Helicobacter pylori gastritis. JAMA 1997;277:1135-9.
Alward WLM, McMahon BJ, Hall DB, Heyward W, Francis DP, Bender TR. The serologic course of hepatitis B surface antigen and e antigen and the development of primary hepatocellular carcinoma in asymptomatic carriers of hepatitis B virus. J Infect Dis 1985;151:604-609.
Heyward WL, Bender TR, Lanier AP, Francis DP, McMahon BJ, Maynard JE. Serological markers of hepatitis B virus and alpha-fetoprotein levels preceding primary hepatocellular carcinoma in Alaskan Eskimos. Lancet 1982;ii:889-891.
Heyward WL, Lanier AP, Bender TR, Hardison HH, Dohan PH, McMahon BJ, Francis DP. Primary hepatocellular carcinoma in Alaskan Natives, 1969-1979. Int J Cancer 1981;28:47-50.
Karron RA, Singleton RJ, Bulkow L, et al for the RSV Alaska Study Group. Severe respiratory syncytial virus disease in Alaska Native children. J Infect Dis 1999;180:41-49.
Singleton R, Morris A, Redding G, et al. Bronchiectasis in Alaska Native children: causes and clinical courses. Pediatr Pulmonol 2000;29:182-7.
Singleton R, Dooley L, Bruden D, Raelson S, Butler JC. Impact of palivizumab prophylaxis on respiratory syncytial virus hospitalizations in high-risk Alaska Native infants. Pediatr Infect Dis J 2003;22:540-545.
Singleton R, Redding G, Lewis T, et al. Sequelae of severe RSV infection in infancy and early childhood among Alaska Native children. Pediatrics 2003;112:285-290.
Redding G, Singleton R, Lewis T, Martinez P, Butler J, Bulkow L, Peters H, Gove J, Morray B, Jones C. Early radiographic and clinical features associated with bronchiectasis in children. Pediatr Pulmonol In press.
