Why Mosquitoes Cannot Transmit HIV
Because human immunodeficiency virus (HIV) is a blood-borne pathogen, concerns have been raised about the possible transmission of HIV by blood-feeding arthropods. Laboratory studies and epidemiologic surveys indicate that this possibility is extremely remote. For biological transmission, the virus must avoid digestion in the gut of the insect, recognize receptors on and penetrate the gut, replicate in insect tissue, recognize and penetrate the insect salivary glands, and escape into the lumen of the salivary duct. In one study by Webb and colleagues, the virus persisted for 8 d in bedbugs (1). Another study by Humphrey-Smith and colleagues showed the virus to persist for 10 d in ticks (2) artificially fed meals with high levels of virus (≥105 tissue-culture infective doses/mL [TCID/mL]), but there was no evidence of viral replication. Intra-abdominal inoculation of bedbugs and intrathoracic inoculation of mosquitoes were used to bypass any gut barriers, but again the virus failed to multiply (1). Likewise, in vitro culture of HIV with a number of arthropod cell lines indicated that HIV was incapable of replicating in these systems. Thus, biological transmission of HIV seems extremely improbable.
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