Background:Parasite infections often result in a switch of the human body’s predominant immune reaction from T-helper 1(Th1)-type to Th2-type.Hence,parasite infections are widely expected to accelerate the progression of human immunodeficiency virus(HIV)infections to acquired immunodeficiency syndrome(AIDS).In the People’s Republic of China,both parasitic diseases and AIDS are epidemic in certain rural areas,and co-infections are relatively common.However,no population-based studies have yet investigated the frequency of HIV and parasite co-infections,and its effects on immune responses.We studied(1)the immune status of an HIV-infected population,and(2)the effect of co-infection of HIV and intestinal parasites on selected parameters of the human immune system.Methods:A total of 309 HIV-infected individuals were recruited and compared to an age-matched and sex-matched control group of 315 local HIV-negative individuals.Questionnaires were administered to all participants to obtain information on sociodemographic characteristics,sanitation habits,family income,and recent clinical manifestations.Two consecutive stool samples and 10 ml samples of venous blood were also collected from each individual for the diagnosis of parasite infections and quantitative measurements of selected cytokines and CD4+T-lymphocytes,respectively.Results:During the study period,79 HIV-infected individuals were not under highly active antiretroviral therapy(HAART)and were thus included in our analysis;the prevalence of intestinal helminth infections was 6.3%and that of protozoa was 22.8%.The most common protozoan infections were Blastocystis hominis(B.hominis)(13.9%)and Cryptosporidium spp.(10.1%).The prevalence of Cryptosporidium spp.in HIV-infected individuals was significantly higher than that in HIV negative individuals(P<0.05).Compared to the non-co-infected population,no significant difference was found for any of the measured immunological indicators(P>0.05).However,the following trends were observed:IFN-γlevels were lower,but
