Toxoplasmosis epidemiology and demographics
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
Serologic prevalence data indicate that toxoplasmosis is one of the most common of humans infections throughout the world. Infection is more common in warm climates and at lower altitudes than in cold climates and mountainous regions. High prevalence of infection in France has been related to a preference for eating raw or undercooked meat, while high prevalence in Central America has been related to the frequency of stray cats in a climate favoring survival ofoocysts. The overall seroprevalence in the United States as determined with specimens collected by the third National Health and Nutritional Assessment Survey (NHANES III) between 1988 and 1994 was found to be 22.5%, with seroprevalence among women of childbearing age (15 to 44 years) of 15%.
Epidemiology and Demographics
United States
There was found to be an overall T. gondii IgG antibody prevalence of 15.8% among persons 12–49 years of age in 1999–2000, indicating that approximately 1 in 6 persons in this age group was infected with T. gondii. No significant changes in T. gondii seroprevalence occurred between 1988–1994 and 1999–2000 for the U.S. population as a whole or for any of the subgroups we examined. It was speculated that changes in meat production with lower levels of T. gondiiin meat might result in a reduction in the prevalence of T. gondii infection in the population. Perhaps the time was not sufficient for changes in meat production and consumption habits to have had an impact, or perhaps the expected declines in T. gondii infection occurred before NHANES III. The prevalence of T. gondii infection declined in U.S. military recruits, when 1965 data were compared with 1989 data and in countries in Europe, such as France and Belgium, during similar periods.
Predicting future trends in T. gondii prevalence in the United States is difficult because we do not have a national estimate of what proportion of T. gondii infections are attributable to undercooked meat exposure or to cat feces, soil, or water exposure. A large European case-control study that examined these factors showed that undercooked meat accounted for the largest portion of risk for T. gondii infection (30%–63%, depending on location). However, until researchers examine the risk factors for T. gondii infection in a case-control study throughout the United States, the most important U.S. risk factors and how to best focus preventive education messages will not be determined.
NHANES gives representative estimates of prevalence for the U.S. population but is not designed to evaluate local T. gondii prevalence levels. Studies have indicated that T. gondii prevalence varies greatly in the United States; this local variation is most likely related to culinary practices, the ability of oocysts to survive in different climates, and the levels of immigration from areas of the world in which T. gondii infection is highly endemic. Nevertheless, NHANES produces useful surveillance data for tracking T. gondii prevalence over time in the United States. We will continue to monitor trends in this nationally representative survey.[1] [2]
Other Regions of World
It is estimated that between 30% and 65% of all people worldwide are infected with Toxoplasmosis. However, there is large variation countries: in France, for example, around 88% of the population are carriers, probably due to a high consumption of raw and lightly cooked meat.[3] Germany, the Netherlands and Brazil also have high prevalences of around 80%, over 80%[4] and 67% respecti ely. In Britain, about 22% are carriers, and South Korea's rate is only 4.3%.[5]
Age
The U.S. NHANES (2004-2005) national probability sample found that 33.1% of U.S. persons above 12 years of age had Toxoplasma-specific IgG antibodies, indicating that they had been infected with the organism. This prevalence has significantly increased from the 1999-2000 data.[6]
Race
In NHANES 1999–2000, the T. gondii antibody prevalence was higher among non-Hispanic black persons than non-Hispanic white persons. This finding may reflect immigration patterns from countries with higher rates of T. gondii infection or soil exposure and culinary practices among these different populations. The seroprevalence among persons born outside the United States tended to be higher in NHANES 1999–2000 than in NHANES III, and the percentage of persons born outside the United States tended to be higher in NHANES 1999–2000 than NHANES III, but these findings were not statistically significant. Clearly, in both NHANES III and NHANES 1999–2000 the seroprevalence is higher among persons not born in the United States than in U.S.-born persons. The NHANES 1999–2000 sample population is not large enough to stratify racial/ethnic groups by foreign-birth status and obtain accurate estimates; however, in a multivariate analysis reported previously that used NHANES III data, being born outside the United States was a significant risk factor for T. gondii seropositivity. However, race/ethnicity did not increase risk (using white non-Hispanic persons as the reference group).
References
- ↑ http://www.dpd.cdc.gov/dpdx/HTML/Toxoplasmosis.htm
- ↑ http://www.cdc.gov/ncidod/EID/vol9no11/03-0098.htm
- ↑ David Adam, Guardian Unlimited.Can a parasite carried by cats change your personality?, 25 Sep. 2003
- ↑ Toxoplasmosis in the Netherlands by the Laboratory for Diagnoses for Infectious Diseases and Screening; RIVM Bilthoven [1]
- ↑
- ↑ Jones J, Kruszon-Moran D, Wilson M (2003). "Toxoplasma gondii infection in the United States, 1999-2000". Emerg Infect Dis. 9 (11): 1371–4. PMID 14718078.