The term prurigo applies to a classic chronic skin disease of children (P. strophulus) which is becoming found very seldom in developed countries, but remains extraordinarily prevalent in tropical areas. This striking geographical distribution relies on its ectoparasitic origin. Some peculiar aspects of prurigo, observed in French Guyana (South America), are reported. The original point is a new aspect of adult acquired prurigo, associated with HIV infection, which appears to be one of the features characteristic of tropical AIDS. This HIV associated prurigo (HAP) is the revelating event, in as high as 20% of HIV infected people, significatively those with less than 200 CD4 cells. HAP appears as a marker of HIV infection with poor sensitivity, but much higher specificity (92%), with no correlation with acquisition's risk factors. Just like infantile prurigo, HAP can be considered an arthropod bite reaction which seems to be enhanced in HIV infected people living in tropical environment.