HIV type 1 transmission by human bite

Although transmission of HIV-1 by human bite is assumed to be biologically possible, few indirect data have been presented to the literature suggesting its occurrence. We describe here a case where we detected a clear instance of HIV-1 transmission by bite. The source patient is a 31-year-old male (S) of unknown HIV-1 status that bit his mother (M) on her hand during a seizure in November 1999. At the Hospital, S was diagnosed with neurotoxoplasmosis, and HIV-1 seropositivity was confirmed. Blood was present at S's mouth and M needed suture in her hand. The exposed female was a 59-year-old widow mother, with no sexual intercourse for the past 10 years. Twenty-seven days after exposure, M presented fever and anti-HIV was positive in one electroimmunoassay (EIA) test, inconclusive in another EIA test, and an indirect immunofluorescence test was negative. Thirteen days later, two EIA tests and Western blot were positive (reactive to gp160, gp120, p24, p17). Western blot performed 3 months after exposure was reactive to gp160, gp120, p66, p55, gp41, p39, p31, p24, and p17. Sera obtained from M at 40 days after exposure was subjected to the double EIA testing strategy. The double testing strategy using a combination of sensitive/less sensitive EIA is able to accurately identify recently infected HIV-1 individuals. Indeed, the sample was negative at the less sensitive modified EIA, and positive at the sensitive EIA, confirming the recent infection of this sample and excluding a possibly false-negative result on the first EIA test.