As we have seen some diseases, like AIDS, may have several routes of transmission. Although I didn't mention it several other diseases may also have sexual transmission as a possible, although not very likely, route of transmission.
Although those suffering from Ebola and related viruses are unlikely to be having sex whilst they are contagious some people do recover from Ebola - 10%-50% depending on the strain. Even though they have recovered from the disease they can still have virus in their semen up to seven weeks after they recovered. Recovered Ebola patients are advised to 'not have sex for 3 months or until tests show that semen is free of the virus.'
A conference presentation from 2001 documents the recovery of Lyme spirochetes by PCR in semen samples of previously diagnosed Lyme disease patients. This, of course, does not necessarily mean active infection is transmitted this way. Some documents state that there are no documented cases of sexually transmitted Lyme disease (eg the CDC here and here) whilst others strike a more cautious note:
The CDC position on sexual intra-human Borrelia burgdorferi (Bb) transmission is that it does not occur. We find no study that addresses sexual transmission of Bb among humans; conversely, we find no study supporting that it does not occur. Inferential data, however, suggest the possibility of human sexual transfer. The data come from sound veterinary studies, the finding of Bb in human semen and breast milk, and by similarity to Treponema pallidum where sexual transfer is abundantly documented. Our clinical experience strongly suggests that predictable, possibly inevitable Bb transfer between sexually active couples occurs.
From: Lyme disease': ancient engine of an unrecognized borreliosis pandemic?
W. T. Harvey, P. Salvato
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