Does our immune system not work with STDs? I am learning about our immune system and how our antibodies work. I don’t understand what happens in which we are able to get re-infected with certain infectious disease if we should have immunity. Im guessing our immune system just doesn’t work properly against these infections?
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What I’m reading here is not exactly correct and more importantly does not correctly answer your question. Bacteria and viruses *can both* be candidates for lifelong immunity or limited/no lasting immunity. The reasons for this come down to antigenic variation- ie the ID tags that the bacteria/virus carry that your body use to identify it. Basically some viruses and bacteria are stable in design. They look the same. Measles is measles is measles (To be comprehensive, over 20 types of measles have been identified per the WHO, but they all show the same ID tags, so our body recognizes them as all the same). However, some bacteria or viruses have lots and lots of variations of ID tags, often ones that recombine and mix together to make new ones (This is where the seasonal flu comes from) (Sometimes the genetics of species specific strains mix and create those really really bad flu outbreaks like the “swine flue” and “bird flu” pandemics that happens years ago.)
With Neisseria gonorrhoeae, it regularly changes its ID tags (It’s pili genes get spliced into new, novel ones). The end result is that every gonorrhea infection is unique. Or at least unique enough that you haven’t had it before. I’ve never looked into just how many variations of pili antigens it can express but safe to say its way more than the number of times any given human would contract gonorrhea (I hope….). The viruses that cause Hepatitis C work the same way. They regularly change their external ID tags so that our bodies can’t recognize them if they were to infect us again (though Hep C tends to be a very chronic disease). This is the main reason there is no effective vaccine for Hep C (but there is for A and B).
Syphilis is an interesting one. I had to read a little bit to answer but in layman’s terms. Syphilis is hard to study, incredibly invasive, and also has enough genetic variation that making a vaccine is challenging (but not impossible), however, because it responds so well to penicillin, need for a vaccine is lessened so it’s taken a bit of a back seat. Someone can feel free to correct me if I’m wrong. Additionally, regarding syphilis, it can establish a ‘latent infection’ in your body, essentially hiding for a time and then returning with a vengeance. While this means nothing on its own, it does speak to the resilience syphilis has as a bacteria and its ability to evade your immune system. I think an easy way to think about this is that something that can hide in the belly of the beast can certainly find its way in again. Common herpes viruses work the same way. If you have chicken pox as a kid, that virus never goes away, it hides in your nerves and can come back out as shingles when you are older.
Finally, with Strep throat (which is caused by a group of bacteria called “group A streptococcus,” it’s the similar issue to gonorrhea. The virus has too many subtypes, too many ID tags, and can change its ID tags over time. You never heard of a kid getting strep throat 200+ times. But that’s what it would take to become immune to all the versions of it, rendering you properly “immune” to strep throat.
As bonus, the common cold works the same way. Typically caused by a class of viruses called rhinoviruses, there’s simply way way too many types floating around, all carrying different ID tags so your body doesn’t recognize them as the same punk kids who tried to sneak into the bar with fakes just last month. If someone caught the common cold enough times, you’d probably eventually become immune to all of them (assuming your immune system is healthy).
This in part explains the admittedly anecdotal phenomenon I’ve heard told time and time again by my medicine colleagues that pediatricians that just start out practice tend to get sick a lot in their first year of practice but then slowly stop getting sick over time. They see a bunch of kids with colds and other viruses and catch them themselves, but as they practice over time, they start to have caught most of the ones endemic to the area and so get sick very rarely. Hence many stories of the 70 year old pediatrician picking up sneezing, slobbering sick children and not getting sick while the new blood keeps their distance, washes their hands carefully and still gets it.
Anyways, hope that helps.
Edit: Clarity and a missing clause.
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