The main thrust of the article is that the "proportion of HIV-positive women in stable heterosexual serodiscordant [where one partner is HIV positive and the other is not] relationships was 47%". I'm not sure why the authors are so surprised because much of their data has been around for five or more years. But this "shows that women are as likely as men to be the index partner [the first to be infected and therefore the one that is assumed to infect the other partner] in a discordant couple".
The bulk of HIV prevention programing assumes that HIV is almost always transmitted sexually in African countries. This includes the assumption that men are far more likely to be the index partner because men are far more likely to engage in 'risky' sexual behavior. However, both of these assumptions are unsupported by evidence. These 'findings' about discordance are more of an indication that the orthodox view of HIV transmission is not correct. There simply doesn't seem to be a close correlation between 'unsafe' sex and HIV transmission.
Sexual transmission of HIV is not particularly efficient. Rough estimates of transmission probability suggest that the probability of a HIV positive man infecting a HIV negative woman may be about 1 in 500. The probability of a HIV positive woman infecting a HIV positive man may be about 1 in 1000. Certain things can make either partner more susceptible to infection and more infectious, but even in discordant couples, transmission rates are only about 10% per year. And even then, the partner infected later is not always infected by their partner. Either way, both may be infected non-sexually!
Transmission through non-sexual modes is many times more efficient. HIV contaminated blood and blood product transfusions may not be very common now, though they still occur. But reuse of injecting and other invasive equipment is probably very common and it is also hundreds or even thousands of times more efficient.
Aso, although HIV transmission doesn't appear to have much to do with sexual behavior, it does appear to have a lot to do with marriage. The paper finds that "marriage as a potential risk factor for HIV infection in 13 African countries showed that previous marriage (average of 16·9% of all HIV-infected people across 13 countries) or remarriage (average of 14·5% of all HIV-infected married people in 13 countries), whether attributable to divorce, separation, or widowhood, were significantly associated with HIV infection risks."