if i know a SP who has seen a client with BBFS, I would not visit her ever. a negative test only says that upto about 3 months ago he is HIV free.
Here is some of the latest info re HIV tests.
The Health Nurse commented on the subject of the NAT test for HIV:
"The HIV DNA PCR (NAAT test) 90% of people would test positive by 10-12 days after being infected and 95-98% of people would test positive 4-6 weeks after being infected."
"...Currently with the latest antibody test in Canada 95% of people who test positive will do so within 34 days of exposure to HIV."
https://perb.cc/vbulletin/showthread.php?134988-HIV-Symtoms-Worries&highlight=antigen
"Since routine HIV antibody tests yield negative results during the first four to five weeks of HIV infection,6 acute infections can be diagnosed during this period only with the use of tests for viral antigens, nucleic acids, or both.
http://www.nejm.org/doi/full/10.1056/NEJMoa042291
There is also the p24 antigen test for HIV which is covered by BC health care:
"The p24 antigen test detects actual HIV viral protein in blood. The test is generally positive from about one week to 3-4 weeks after infection with HIV.
http://labtestsonline.org/understanding/analytes/p24/tab/test
"Fourth generation tests
"Some of the most modern HIV tests combine P24 antigen tests with standard antibody tests to reduce the ‘diagnostic window’. Testing for antibodies and P24 antigen simultaneously has the advantage of enabling earlier and more accurate HIV detection.
"In the UK, fourth generation tests are the primary recommendation for HIV testing among individuals, but are not offered by all testing sites.1 During June 2010, the FDA approved the first fourth generation test in the United States.2"
http://www.avert.org/testing.htm
These tests are useful to identify an infection of HIV in the early "acute" stage of HIV so it can be treated more effetively and when it is the most infectious.
"...the HIV antibody test will not detect a recently infected donor, so some blood banks use a p24 antigen or HIV nucleic acid test in addition to the basic antibody test to detect infected donors during that period."
http://en.wikipedia.org/wiki/Blood_donation
Re HIV tests, you are safest getting the usual antibody test together with either NAT or p24 antigen.
"In 2009 blood screened for HIV in Greater Accra, Ghana amounted to 33, 294 units of blood, of which 3. 68 percent was found to be HIV positive. 45 Ghana tests 100 percent of its blood donations, however this is done using only antibody tests. Therefore the window period remains a significant interval, which suggests some units may continue to pass through screening undetected.
"In October 2005, South Africa introduced NAT testing and as a result there were no cases of HIV transmission by blood transfusion reported to the haemovigilance programme, a transfusion surveillance system. 46 47
"The availability of nucleic acid tests (NAT) , which reduces the window period and makes testing much more accurate, helped to support the argument for a change in the ban against MSM donating. These tests have been found to almost eliminate the possibility that HIV infected blood will pass through the testing stage, even in countries with high prevalence. 33"
"If a person receives a blood transfusion with HIV-infected blood, there is a 95 percent risk they will become infected with the virus. 4 However the chances of becoming infected with HIV through a blood transfusion varies between countries depending on the level of safety precautions in place, and there is a notable difference between high and low-income countries. In the UK, the risk is now 1 in 5 million. 5"
http://www.avert.org/blood-safety-hiv.htm
One in 5 million. This gives some idea of the HIV risk in having one act of bareback sex with an individual (aged 17 to 65) who has just had this NAT test & donated blood. Certainly it would be riskier with a FT gogo girl or streetwalker in Bangkok, but the million dollar question is, by how much. Note also that recieving HIV in blood as a donor will almost surely infect you (95 percent of the time, as stated) , whereas one act of BB sex with an infected lady is very unlikely to cause you harm (maybe 1 in 2000 chance of getting HIV)*. Factor into that the miniscule chance a SP who recently tested negative for STIs (using NAT & antibody tests) is HIV positive and the conclusion is your odds of getting HIV from her are extremely low, such as when using a condom with a SP whose HIV status you have no clue about.
*So the BBFS risk would be more like 5 million X 2000.