Is Necator americanus approaching a mutualistic symbiotic relationship with humans?

Trends Parasitol. 2001 Apr;17(4):169-72. doi: 10.1016/s1471-4922(01)01941-9.


The hookworm Necator americanus establishes infections of impressive longevity in the immunologically hostile environment of its human host. In the process, it promotes pronounced T-helper 2 (Th2) cell activity, which in turn seemingly affords the host at least a degree of protection. Given the relatively asymptomatic nature of infection, we argue here that Necator americanus might be approaching a mutualistic symbiotic relationship with humans. In our view, infection is controlled by the immune system while being supported by a subtle immune-evasion strategy that is tolerated and possibly beneficial to the host in certain immunological circumstances, such as in counterbalancing potentially damaging Th1 responses.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Helminth Proteins / chemistry
  • Host-Parasite Interactions
  • Humans
  • Molecular Sequence Data
  • Necator americanus / physiology*
  • Necatoriasis / immunology
  • Necatoriasis / parasitology*
  • Symbiosis*


  • Helminth Proteins