jfh@ames.arc.nasa.gov (Jack Hamilton) (07/29/90)
There have been several articles in the newspapers recently about a case of supposed transmission of HIV between a dentist and a patient. Naturally, this has people worried. The patient claims to have had no other possible contact with HIV other than having two teeth extracted by that dentist. Both the dentist and the patient agree that the dentist wore a mask and gloves, and followed all the safety guidelines. My first reaction to hearing this was "Sure, she says she didn't have any other contact with HIV. That's what they all say. How do we know what she's been doing in her private life?" Only one of the articles I've read answered that question, and I'll pass along what it said (paraphrased from an article in the San Francisco Examiner, originally in the Chicago Tribune): Scientists did took blood cells from the dentist and the patient and did genetic sequencing on thw virus. That involves decoding the DNA of the virus and creating a kind of genetic fingerprint. They compared the fingerprints with each other, and with the fingerprints of other virus samples obtained here and abroad. The viruses taken from the dentist and his patient were not exactly alike, but were closer than any other pair of samples taken from people who had not had bodily fluid contact. The difference between the codes for the virus coat were different by only 1.2 percent, whereas the difference between samples is usually 5 to 10 percent. Furthermore, the two samples shared a piece of code in the V3 loop which the lab had not seen in any other HIV virus. (The V3 loop may play a role in determining the virus's infectivity.) The article "the CDC's weekly medical bulletin", which I assume is the MMWR, stressed that that other sources of infection cannot be ruled out, but that the lab findings were consistent with dentist-patient transmission. There is no evidence of any other such cases, and it is also possible that both were infected with a new, more stable and more infectious strain of the virus. The American Dental Association said that the CDC report is inconclusive and does not serve the best interests of the public and the dental profession. Interesting and kind of scary. We really need more information. ---------- Copyright 1990 by Jack Hamilton. Copyright abandoned. There are no restrictions on the private or public redistribution of this material, with or without attribution. -- ------------- Jack Hamilton jfh@netcom.uucp