Can you please tell me if HIV/AIDS can be transferred from humans to animals and then back to other humans? One person in our family is HIV positive, and we have a puppy and kitten, both of whom love to bite and scratch. My concern is that should they draw blood from the HIV-positive person and then draw blood from another person, the second person could become infected. I am sorry if this seems a silly question, but it does concern our family health.

Trish

I have previously discussed in this column how HIV (the virus that causes AIDS) is transmitted, but I think that it is worth further review. When HIV infection first appeared in the United States, it soon became apparent that most people were infected in one of three ways: through sex, by contact with blood or blood products (including blood transfusion and needle-sharing by drug abusers) and from an HIV-infected mother to her child. Because of the severity of the illness, there have always been fears that there were other means of transmission. Indeed, there are some people who are infected with HIV for whom the route of transmission is unknown. However, the vast majority of cases fit into one of the three above categories.
HIV cannot be transmitted by casual touching, such as a handshake, a kiss on the cheek or lips, or other non-intimate contact. Since HIV does not survive long outside the human body, it cannot be transmitted by contact with a towel or a toilet seat. No animal has ever been shown to transmit the virus to humans.

The possibility that HIV could be spread by insect bite was a concern at the beginning of the epidemic, but this has never been shown to occur. If you think about it, HIV transmission by insect bite does not make sense. If mosquitoes, for example, spread the virus, we would see a different pattern of HIV infection than actually exists, with far greater numbers of infected people who lacked the usual risk factors. We would see HIV-infected children who were not born to infected mothers and who had no other known risk factor for HIV infection, as well as many more elderly people with the infection than currently exist.

Contact with pets has never been shown to result in HIV. When your pets draw blood, I doubt that they ever draw a substantial amount. I am sure that the family member with HIV would tell you if they had a substantial blood spill of any kind, especially if it involved one of the pets. Remember also that there would not be much blood left on the pet's claw to be transmitted, and that the virus would not survive on the claw for long, in any case. There is, no doubt, a theoretical possibility that such transmission could occur, but I think that the possibility is so remote as to not worry about it.

I tell my patients with HIV the following. Try your best not to allow any infected blood to contact others. Cover open cuts and sores and do not allow others to dress any wounds without gloves. While toothbrushes and other such objects have resulted in transmission only very rarely, I inform my patients not to take any chances and to avoid sharing such things. I also tell them that if sharing does occur inadvertently, not to worry too much. The risk of transmission in a household is extremely low if intimate contact does not occur.