We wish to make some comments in response to the letter by Hung and others regarding our results published in the American Journal of Tropical Medicine and Hygiene.1 Using death certificate data, we identified human immunodeficiency virus (HIV) infection as a coexisting condition in 14 (10.4%) of 134 amebiasis-associated deaths in the United States over the period, 1990–2007. HIV infection was more common among amebiasis-associated deaths than in the control, non-amebiasis group (matched odds ratio = 7.7, 95% confidence interval, 3.16, 18.77). Twelve (86%) of the 14 HIV and amebiasis co-infected cases were male.
Interpretation of these results is challenging. Whether HIV is directly associated with amebiasis is unclear from our study because the observed association may be confounded by the greater likelihood of exposure and infection with Entamoeba histolytica among men who have sex with men (MSM), who are also at increased risk of HIV infection. Death certificates do not contain information regarding sexual orientation precluding further analysis. Small numbers of females co-infected with HIV and amebiasis prevents us from stratifying by gender to see if this association is even specific to males. Additional confounders may be present. The limitations of death certificate data should also be considered.
We thank Hung and others for their interest in our results and agree that further research is necessary to define any relationship between HIV infection and E. histolytica infection, especially in MSM.
Gunther J, Shafir S, Bristow B, Sorvillo F, 2011. Short report: amebiasis-related mortality among United States residents, 1990–2007. Am J Trop Med Hyg 85: 1038–1040.