Infection

Bacteria, viruses, and parasites are continuing problems. Antibiotics work well against most bacteria; however, antibiotic-resistant strains are developing. Since viruses aren't active until they take over a cell, they are immune to antibiotics, and medicine cannot yet do much against them. There are many kinds of parasites that may need individual medical techniques.

Our immune system is quite effective at dealing with most infections. However, it needs to learn by experience--it is generally most effective at fighting organisms that it can recognize on a molecular level. Diseases can be very clever in evading it. Some diseases, such as Ebola, progress too rapidly for the immune system to respond. Syphilis survives by being stealthy and surrounding itself with the body's own chemicals to camouflage itself. Herpes splices itself into the genes of the body's cells, so the immune system can't detect it and wipe it out. HIV directly attacks the immune system.

Nanobots have several advantages over the immune system. They will not be susceptible to attack by natural pathogens. They will have computational resources unavailable to immune cells. They can be programmed to find and fight diseases they have never encountered--when a new disease shows up, as soon as it is analyzed everyone's nanobots can benefit. Likewise, the system can be activated based on external knowledge of the likelihood of a disease; the nanobots won't have to waste energy looking for malaria in winter. Nanotech will give us more options for cleaning up after a disease, since corrupted genes will be repairable without killing the affected cell.

Some diseases, such as cholera and tetanus, live in the environment; without scrubbing the whole earth, we can't get rid of them entirely, so we will need to maintain an immune system against them. But many diseases can't survive without humans to infect. With great effort, we managed to eradicate smallpox using 1970's technology. Cheap manufacturing would allow the creation of billions of doses of highly effective treatments that would be easy to distribute and administer; the main obstacles to wiping out many diseases worldwide would be political, not economic or technological.