HIV Epidemic
The HIV epidemic first broke in the 1980s, and although prevention efforts have increased in the last decade, 36.7 million individuals still live with the disease and 2 million new individuals are infected every year with no end in sight. The spread of HIV can be represented by the branching process model we discussed in class. Each node represents a person, and most edges represent sexual relations between two individuals, while other edges represent contact through shared needles or breast milk. Scientists hypothesize that if the transmission rate were reduced by 50%, then the basic reproductive number would drop below 1 and lead to eventual elimination of the disease.
As we learned in class, there are two ways to reduce the reproductive number: reduce the probability of passing on the disease or reduce the number of people that an infected individual could potentially transmit the disease to. The distribution of billions of condoms has made a significant impact on the probability (p) that the disease is passed on through sexual relations, and education and awareness efforts have encouraged individuals to limit the number of people (k) they engage with. However, most people living with HIV or at risk for HIV live in middle or low-income countries, and they do not have easy access to prevention, care, or treatment. So while the methods of lowering the reproductive number exist, the real challenge is spreading the resources and information throughout the whole network so that people can take action.
Despite how long the disease has persisted and how prevalent it has become in certain communities, the U.N. has set a goal of ending the HIV epidemic by 2030. Because there is no cure available right now, completely eradicating the disease is improbable, but their goal is to drive HIV down to a low-enough level so that it is no longer considered a major health problem. But even if the reproductive number drops below 1, the relatively long lifespans of infected individuals indicates it may take many more decades before HIV is completely eliminated.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2848261/