Efficacy of thermoplastic elastomer and latex condoms as viral barriers.

ABSTRACT

PIP: A microbiologist at Loma Linda University in California used T7 (100 nm), a virulent bacteriophage of Escherichia coli, and the poliovirus type 1 (PC-1) (27 nm) to compare the efficacy of the viral barrier of latex and new thermoplastic elastomer (TPE) condoms. The scientist used a passive test and a simulated intercourse model to compare the 2 condom types. The simulation consisted of a condom-covered disposable centrifuge tube with 4 ml of virus which was inserted into an outer condom with 2 ml of virus-free medium. This apparatus was withdrawn and inserted 30 times within 30 seconds into a commercially produced latex vagina. The tests with T7 used 15 condoms of each brand. The tests with PV-1 used 14 condoms of each brand. The only TPE condom brand was Tactylon. Latex condom brands were Shiek, Trojan-Enz, and Lifestyles. No virus passed through the barrier during the passive test. T7 leaked through 2 latex condoms (13.3%) of the same brand (Trojan-Enz) during the simulated intercourse test. On the other hand, PV-1 did not leak through any of the condoms. Tactylon effectively prevented the passage of both T7 and PV-1. These findings confirmed that latex condoms tend to block passage of both small and large viruses. They indicated that TPE condoms also block passage of small and large viruses. Thus, the effective maximum pore size in all of the TPE condoms and in all but 2 of the latex condoms was too small to let HIV (80-120 nm) and hepatitis B virus (about 42 nm) filter through. Clinical trials have indicated the breakage rate of TPE condoms is not significantly different from that of latex condoms. Advantages of the TPE condom are its ability to resist environmental effects, e.g., ultraviolet light and heat, which deteriorate the latex condom and it does not have antioxidants and accelerators the latex condom has which cause allergic reactions, e.g., dermatitis.