Coronary heart disease & C. pneumoniae
Coronary heart disease is a common manifestation of atherosclerosis and appears to be a multifactorial disease. Genetic [Marenberg et al., 1994] as well as environmental factors have been implicated. Smoking, hypertension and high cholesterol are major recognized risk factors but others are likely to be important. The World Health Organisation MONICA (monitoring of trends and determinants in cardiovascular disease) project found that these three factors accounted for less than 25% of the variance in cardiovascular mortality in men from 35 populations [Anon, 1994].
At first sight, the epidemiology of C. pneumoniae does not suggest that it is an important risk factor for coronary heart disease. There seems to be no correlation between the prevalence of C. pneumoniae infection and coronary death rates. For instance, the coronary death rate for men throughout the world varies between 50 per 100,000 in Japan to rates that are ten times higher in Scotland [Thom, 1989]. In contrast, the seroprevalence of C. pneumoniae is uniformly high throughout the world [Mendall et al., 1995; Kanamoto et al., 1991]. Nevertheless, there is indirect evidence to suggest that infections may be important in coronary heart disease and it is important to remember that infections other than C. pneumoniae are likely to be important [Espinola-Klein et al., 2002]. Some have speculated that the decline in coronary mortality seen recently in developed countries is due to the use of tetracycline [Anestad, Scheel & Hungnes, 1997] and we ourselves have found in a study of the population of England and Wales, that death rates for MI are associated with household size, a factor likely to be important in the transmission of infection [Wong, Dawkins & Ward, 2001].
[YW] Updated March 2002 NEXT: CAD serological evidence
Anestad, G., Scheel, O. & Hungnes O. (1997). Chronic infections and coronary heart disease. Lancet 350, 1028. [+ related articles, see hyperlink]
Anon. (1994). Ecological analysis of the association between mortality and major risk factors of cardiovascular disease. The World Health Organisation MONICA project. International Journal of Epidemiology 23, 505 - 516.
Espinola-Klein, C. et al., (2002). Impact of infectious burden on extent and long-term prognosis of atherosclerosis. Circulation 105, 15 - 21. [Emphasizes importance of overall pathogen burden].
Kanamoto, Y., Ouchi, K., Mizui, M., Ushio, M. & Usui, T. (1991). Prevalence of antibody to Chlamydia pneumoniae TWAR in Japan. Journal of Clinical Microbiology 29, 816 - 818.
Marenberg, M. E., Risch, N., Berkman, L. F., Floderus, B.& Defaire, U. (1994). Genetic susceptibility to death from coronary heart disease in a study of twins. New England Journal of Medicine 330, 1041 - 1046.
Mendall, M.A., Carrington, D., Strachan, D., Patel, P., Molineaux, N., Levi, J. et al. (1995). Chlamydia pneumoniae_: risk factors for seropositivity and association with coronary heart disease. Journal of Infectious Diseases 30, 121 - 128.
Thom, T. J. (1989). International mortality from heart disease: rates and trends. International Journal of Epidemiology 18, (Supplement) S20 - S28.
Wong, Y. K., Dawkins, K. D. & Ward, M. E. (2001). The association between deaths from myocardial infarction and household size in England and Wales. Journal Of Cardiovascular Risk 8,159-63. [Analysis of census data. Deaths from myocardial infarction in population of England & Wales related to household size after correction for social deprivation. Consistent with role for infection.]