HIV-1/parasite co-infection and the emergence of new parasite strains

James O. Lloyd-Smith, Mary Poss, Bryan T. Grenfell

Research output: Contribution to journalReview articlepeer-review

34 Scopus citations


HIV-1 and parasitic infections co-circulate in many populations, and in a few well-studied examples HIV-1 co-infection is known to amplify parasite transmission. There are indications that HIV-1 interacts significantly with many other parasitic infections within individual hosts, but the population-level impacts of co-infection are not well-characterized. Here we consider how alteration of host immune status due to HIV-1 infection may influence the emergence of novel parasite strains. We review clinical and epidemiological evidence from five parasitic diseases (malaria, leishmaniasis, schistosomiasis, trypanosomiasis and strongyloidiasis) with emphasis on how HIV-1 co-infection alters individual susceptibility and infectiousness for the parasites. We then introduce a simple modelling framework that allows us to project how these individual-level properties might influence population-level dynamics. We find that HIV-1 can facilitate invasion by parasite strains in many circumstances and we identify threshold values of HIV-1 prevalence that allow otherwise unsustainable parasite strains to invade successfully. Definitive evidence to test these predicted effects is largely lacking, and we conclude by discussing challenges in interpreting available data and priorities for future studies.

Original languageEnglish (US)
Pages (from-to)795-806
Number of pages12
Issue number7
StatePublished - Jun 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Infectious Diseases
  • Animal Science and Zoology
  • Parasitology


  • Drug resistance
  • Emerging infectious diseases
  • Immunosuppression
  • Mathematical model
  • Population heterogeneity
  • Zoonosis


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