Not having done my homework yet, but thinking ahead, it seems that thinking about the various types of viruses, as metaphor for memes, could be useful. As we learn more about memetics, then we'll want to go on to applied memetics as well, where the knowledge will be used, one hopes, for the betterment of life on earth. Much of our current management of viral infections and disease also came from learning how viruses live, evolve, and replicate. From that information, we developed ways to manage or treat many viral illnesses.
Some examples, of viral interactions with humans, include -
Hepatitis A, you get it, you're miserable for a while, and your immune system fights it off, then it's gone. Those antibodies are good for life, you won't get it again. Spread by unsanitary conditions.
Hepatitis B, you get it, and may either develop a carrier state or might fight it off. People who fight it off may become immune. People with the carrier state can infect others. It can lead to fatal complications. More than 2 billion people worldwide have been infected with this virus, similar to the number of christians worldwide. Spread by intimate contact, blood, cuts, sex.
Ebola virus, most people who get this die within a couple of weeks, spread through body fluids. People bleed from multiple orifices, enhancing the spread, but it kills off its hosts so quickly, & has such limited transmissibility, that outbreaks are quite limited.
Most cold viruses are very easily transmitted via particles from coughing and hand to mouth contact, mutate rapidly, you get it, you get over it, and it's gone. But you probably gave it to someone else.
And then there are the scary ones like variations of influenza that are highly transmissable and rapidly lethal. These fortunately dont come up very much, but they wind up killing their hosts off rapidly then die out because there are no susceptable hosts remaining.
Offhand, I can't think of a human virus that benefits its host. There are some viruses that infect bacteria and can pass on antibiotic resistance, so that the bacteria with the virus survive and replicate, while the bacteria that dont have the virus die when exposed to the antibiotic.
There are also viruses like Fig Mosaic Virus. Almost all figs are infested with this virus. In most cases, it doesn't kill the tree. It is thought to weaken the trees, slightly, and reduce fruit yields, but basically the effect is mild. Not easily transmissible, probably from biting insects, but mainly from propagation of infected stock into new trees.
I can think of similar concepts with memes. A meme that catches on quickly, spreads from person to person, and then dies out, would be like a cold virus. Silly fads would be an example.
A meme that infests it's host with the potential to last lifelong, but some victims develop serious complications while others become immune, requires close contact, and can occasionally be fatal, would be like Hepatitis B. As noted above, christianity, or parts of it, might be an example
A meme that is highly virulent and infects its victims quickly, then dies out when they die out would be like ebola virus. An example would be certain cults, such as Heaven's Gate or Jones Town.
A meme that infects its host, but is beneficial, improving the survival of the host while at the same time propagating itself would be like the antibiotic-resistance viruses that infect certain bacteria. An example would be the application of science to medicine. As science cures disease, the scientific meme spreads and also improves survival of those who are infected with it.
A meme that infects its host, does not do significant damage, just kind of hangs out and slows it down all little, would be like fig mosaic virus. Example? Physical ideals of perfection that lead people to low self esteem, so they accept less in life and may be less competitive for jobs or spouses.
These are probably quite flawed as metaphors, but I thought I would share them and see what others think. A ramble to help move the conversation forward.