title: Co-infection with Schistosoma mansoni and Human Immunodeficiency Virus-1 (HIV-1) among residents of fishing villages of north-western Tanzania.
abstract: BACKGROUND
  Co-infection with S. mansoni and Human Immunodeficiency Virus-1 (HIV-1) has been described in sub-Saharan Africa. However, few community-based studies have been conducted to assess the association between the two diseases. The present study examined whether the infection with HIV-1 is associated with an altered susceptibility to S. mansoni infection by comparing the prevalence and intensity of S. mansoni infection among those infected and not infected with HIV-1. Any influence of HIV-1 associated immunodeficiency on the intensity of S. mansoni infection was also investigated.
  
  
  METHODS
  A cross-sectional study was conducted among 1,785 randomly selected adults (aged 21-55 years) in fishing villages of north-western Tanzania. Single stool samples were obtained and examined for S. mansoni eggs using the Kato Katz technique. Finger prick and venous blood samples were collected for HIV-1 screening and CD4(+) cell quantification. Demographic information was collected by questionnaire.
  
  
  RESULTS
  Of the 1,785 individuals from whom complete data were obtained, 854 (47.85%, 95% CI; 40.46 - 56.57) were infected with S. mansoni and had a mean intensity of 183.21(95% CI; 165.61-202.70) eggs per gram of faeces (epg). A total of 125 individuals (6.29%, 95% CI 3.59-11.04) were infected with HIV-1 and only 40% (n=50) of them were co-infected with S. mansoni. No differences in prevalence of S. mansoni infection or intensities of infection, as estimated by egg count (epg), were observed between HIV-1 sero-positive individuals and HIV-1 negative individuals. In generalized regression models (adjusted for sex, age, occupation, residence and level of education), being infected with HIV-1 did not increase the risk (APR=1.01, 95%; 0.83-1.21, P=0.93) or intensity (AOR = 0.84, 95% CI; 0.56-1.25, P = 0.33) of S. mansoni infection. Among individuals co-infected with HIV-1 and S. mansoni infection, the intensity of infection (epg) was not associated (P = 0.21) or correlated (P = 0.13) with CD4(+) cell counts.
  
  
  CONCLUSIONS
  Our findings suggest that HIV-1 infection may not have a major effect on S. mansoni infection or on the excretion of eggs from the co-infected individuals. However, further studies are needed to understand the biological interaction between HIV-1 and S. mansoni in a large cohort of co-infected individuals.
authors.affiliation: Department of Medical Parasitology and Entomology, Weill School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania. humphreymazigo@gmail.com.|Department of Disease Control and Environmental Health, School of Public Health, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda. humphreymazigo@gmail.com.|Department of Pathology, Division of Microbiology & Parasitology, Cambridge University, Tennis Court Road, Cambridge, CB2 1Q3 P, UK. humphreymazigo@gmail.com.
authors.forename: Humphrey D
authors.initials: HD
authors.lastname: Mazigo
authors.affiliation: Department of Pathology, Division of Microbiology & Parasitology, Cambridge University, Tennis Court Road, Cambridge, CB2 1Q3 P, UK. dwd10@cam.ac.uk.
authors.forename: David W
authors.initials: DW
authors.lastname: Dunne
authors.affiliation: Department of Pathology, Division of Microbiology & Parasitology, Cambridge University, Tennis Court Road, Cambridge, CB2 1Q3 P, UK. sw320@cam.ac.uk.
authors.forename: Shona
authors.initials: S
authors.lastname: Wilson
authors.affiliation: National Institute for Medical Research, Mwanza Research Centre, P.O. Box 1462, Mwanza, Tanzania. kinunghi_csm@hotmail.com.
authors.forename: Safari M
authors.initials: SM
authors.lastname: Kinung'hi
authors.affiliation: Department of Pathology, Division of Microbiology & Parasitology, Cambridge University, Tennis Court Road, Cambridge, CB2 1Q3 P, UK. acp44@cam.ac.uk.
authors.forename: Angela
authors.initials: A
authors.lastname: Pinot de Moira
authors.affiliation: Department of Pathology, Division of Microbiology & Parasitology, Cambridge University, Tennis Court Road, Cambridge, CB2 1Q3 P, UK. fmj20@cam.ac.uk.
authors.forename: Frances M
authors.initials: FM
authors.lastname: Jones
authors.affiliation: Department of Medical Parasitology and Entomology, Weill School of Medicine, Catholic University of Health and Allied Sciences, P.O. Box 1464, Mwanza, Tanzania. dmorona@gmail.com.
authors.forename: Domenica
authors.initials: D
authors.lastname: Morona
authors.affiliation: Department of Disease Control and Environmental Health, School of Public Health, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda. nuwahaf@yahoo.co.uk.
authors.forename: Fred
authors.initials: F
authors.lastname: Nuwaha
mesh_terms: D000328:Adult; D000818:Animals; D060085:Coinfection / Q000453:epidemiology / Q000469:parasitology* / Q000821:virology*; D003430:Cross-Sectional Studies; D005243:Feces / Q000469:parasitology; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000469:parasitology / Q000821:virology*; D015497:HIV-1 / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012424:Rural Population; D012550:Schistosoma mansoni / Q000502:physiology*; D012555:Schistosomiasis mansoni / Q000453:epidemiology / Q000469:parasitology* / Q000821:virology; D013636:Tanzania / Q000453:epidemiology; D055815:Young Adult