Toxoplasmosis Mortality, Associated Medical Conditions, and Productivity Losses in the United States, 2000-2010: A Matched Case-Control Analysis

Background: Toxoplasma gondii is a well-known parasitic infection associated with HIV/AIDS, but its status as the second most common foodborne illness is often overlooked. Few studies have quantified toxoplasmosis mortality burden in the United States.

Methods: We examined national multiple cause-of-death data and estimated lost productivity from this disease for the period 2000-2010. Crude and age-standardized rates of toxoplasmosis-related mortality were computed for sex, race, year, and state of residence. A matched case-control analysis was conducted to examine associations between comorbid conditions and toxoplasmosis deaths. Productivity losses due to premature death were calculated using the human capital approach which estimated the present value of lifetime productivity.

Results: A total of 789 toxoplasmosis deaths were identified as either an underlying or associated cause of death during the study period. The average annual age-adjusted mortality rate was 0.03 per 100,000 population. Poisson trend analysis showed an annual percent change of -11.7% (p<0.0001) over the study period. Blacks and Hispanics had the highest burden of toxoplasmosis-related mortality as compared to whites, with an age-adjusted rate ratio of 8.3 (95% Confidence Interval [CI], 7.3-9.4) and 3.5 (95% CI, 3.1-4.0), respectively. The age-adjusted rate for toxoplasmosis death in males was twice that of females. For the matched case-control analysis, several comorbid conditions were associated with toxoplasmosis deaths, including HIV (OR=27.7; 95% CI, 21.8-35.4), Hodgkin/Non-Hodgkin lymphomas (Odds Ratio [OR]=5.9; 95% CI, 4.0-8.7), leukemia (OR=3.1; 95% CI, 1.95-4.85), and connective tissue disorders (OR=4.4; 95% CI, 2.7-7.2). The total productivity losses were $814.5 million during the 10-year period.

Conclusions: Although trends for this infection have declined in the last decade, toxoplasmosis remains an important cause of preventable death among several subgroups.