Dear Dr HHH and Dr Hook,

I am a Chinese male, and I am uncircumcised. I am very happy that I have found this forum to ask questions!

Yesterday, I had protected sex with a sex worker. I also received protected oral sex. I always only have safe sex. After looking at this forum and your answers today, I find a new concept called the "lambskin condom". I have never used or even heard of such condoms. I don't really remember what kind of condoms the sex worker used yesterday, and unfortunately, I can't contact her because I deleted her number by accident. After a quick search online, I can't find any common Chinese brands that sell such condoms. But of course, I can't be sure about it. So, my questions are:

1. If we assume that the sex worker used such condoms, can I assume that the condoms provided a similar level of protection against HIV as latex condoms do? I see in old questions you claimed that lambskin condoms are almost as good as latex condoms for HIV prevention. Can you confirm that this still holds?

2. I would like to do a risk calculation for myself, just as you did for some other users. The sex worker was by appointment, and the price was 2500 Chinese Yuan (about 370 dollars) for one hour. I think she's an expensive sex worker in China, but I don't know how you would judge that? If I assume a 1% chance the sex worker has HIV, do you think this assumption is reasonable?

3. I test for HIV and STIs once or twice per year, and the last time was 2 months ago. Everything was negative. I would rather not test immediately after this exposure, and I would like to stick with my usual testing plan. Do you agree with my plan?

Thank you for your help!

Natural membrane condoms are constructed from animal tissues, most commonly but not always from slaughtered lambs, hence "lambskin". It is the outer membrane present on all mammals' intestines, which (obviously) has a tubular shape. It's the same material used as casing for the innumerable meat sausages produced for centuries in all cultures around the globe. Condom experts speculate that the very first condoms (thousands of years ago) were made from these tissues. Until about 100 years ago, animal membranes were the dominant (or only?) condom material, before rubber, latex, and plastics came around in the industrial era. Today, some persons find the sexual "feel" is better with natural than with a rubber or plastic membrane (and if you don't mind a personal interjection, I agree!).

However, theoretical issues exist for the effectiveness of natural membrane condoms in preventing HIV and other STIs, because there are natural pores in the membrane. The pores are much smaller than sperm, so no problem in regard to contraception, but they are larger than bacteria and viruses. As a result, health education advice is filled with warnings about potential risk of HIV and other STIs, i.e. that natural membranes condoms may not protect as well as latex and polyurethane. On the other hand, hydrostatic pressure -- the physics of fluids, including passage through small apertures and spaces -- argues against any real risk. High pressures (maybe several kilograms per cm2?) are required to force aqueous fluids through such small pores. And when it comes to condoms, clearly any barrier is better than none. Finally, I am unaware of any reports that someone acquired HIV or other STI because a natural membrane condom was used instead of latex or polyurethane -- or even rumors among my many HIV expert colleagues. Most likely it has never happened, or so rarely that the increased risk can be ignored.

Accordingly, for 30+ years, my personal advice for persons at risk has been that if natural membrane condoms are most acceptable -- and especially someone will use them but not latex or polyurethane -- by all means use lambskins! While I cannot guarantee as good protection, my bet is that it makes no significant difference. (And from my understanding, natural membranes are less likely to break, always a consideration for latex).

In looking online in response to your question, I learned that currently natural membrane condoms comprise 5% of the market in the United States. My guess is that it may be even lower in China. (Forgive me if I characterize your country, as it has industrialized so dramatically in the past few decades, as likely going higher tech and less likely that manufacturers to use animal products. I really have no idea, just a guess.) I found the following website about condom production in China. It doesn't mention natural membranes versus other materials, but with some diligent online searching you might find such data.  https://www.businesswire.com/news/home/20190528005509/en/China-Condom-Industry-Report-2019-2023---ResearchAndMarkets.com

Finally to your questions:

1. It seems unlikely your sex worker contact used a natural membrane condom, but probably it would not matter if she did. 

2. I have zero knowledge of the epidemiology of HIV in China. Even if I did, you're a giant country, and undoubtedly the prevalence of HIV in sex workers varies widely across provinces, metropolitan areas, etc. I cannot project my understandings from the US and Western Europe to your country. But it seem likely the same principles apply:  that upscale, expensive sex workers, by appointment, are at low risk of having HIV and other STIs. In any case, with a condom protected exposure your risk probably was zero or close to it.

3. I believe your current plan is exactly the right one.

I hope this long response has been helpful. Let me know if anything isn't clear.

HHH, MD

I’m not sure if I am allowed to start a new topic. I have a follow-up question which is unrelated to condom types. I have no more questions after this new question.

Sometimes my scrotum, penis and skin with pubic hair feel itchy, and my hair follicles sometimes make my genital area feel sensitive and slightly sore, especially when I sweat and when I scratch them. I guess I may have genital eczema (it’s just my guess). However, I can’t find any open sores or visible wounds on and around my scrotum or penis. There may be some pimples and small abrasions, but I don’t think my skin is broken, or at least it’s not visible to me. Of course there is no blood. I think I could see it if there was blood.

Do you think the above would increase my HIV risk during vaginal and oral sex?

Thanks again for your time. I wrote my question with the help of Google translation. If anything is unclear to you, please let me know.

Thanks for the thanks. I'm glad to have helped.