Expert: Terry B - 9/6/2007

Question
My four year old son had to get labs for kidney disease, and on the way out of the lab, I noticed that there were four or five large drips of blood on the floor.  I am not sure if they were dry or not, and am wondering if there is any risk if we would have stepped on them?

Answer
Dear Amy:

Peace.  Anytime there is blood present there is some risk of exposure to bloodbourne pathogens.  The number of factors necessary for an HIV transmission to occur from the drips on the floor, however, suggest that there is no real risk to you or your son:

1) The fluid would need come from a person infected with HIV (the highest reported rates are at worst about 1/3 in some sections of sub Saharan Africa, and about 1-2% in the US);
2) The blood would need be in fluid state - drying destroys the structure of Human Immunodeficiency Virus;
3) The fluid blood from an infected person would need to touch skin or mucous membrane, and;
4) The amount, concentration of the virus in the blood, frequency, duration of the exposure, and many other factors contribute to or detract from the chances (or relative risk) of infection.

In short, an HIV transmission from the drops of blood is most unlikely.

Should you notice something similar again, however, please notify the staff so they can clean up.  Other diseases are more easily transmitted than HIV, and any bodily fluids on the floor are a potential (if small) risk.

I hope this helped.

Terry