Final answer:
STIs are caused by various pathogens including bacteria, viruses, and parasites, with examples like trichomoniasis caused by protozoa, and pubic lice which are insects. Bacterial STIs like chlamydia, gonorrhea, and syphilis can be cured, whereas viral STIs such as HIV/AIDS do not have a cure.
Step-by-step explanation:
Sexually transmitted infections (STIs) are caused by a variety of pathogens, including bacteria, viruses, and parasites. For instance, the protozoa known as Trichomonas vaginalis leads to trichomoniasis, and this parasitic STI is prevalent among young people, causing symptoms like itching and burning. Pubic lice, which are insect parasites, also result in an STI by irritating the skin in the pubic region and sucking blood from their host.
On the bacterial side, common STIs such as chlamydia, gonorrhea, and syphilis can typically be cured with antibiotics. However, viral STIs like genital herpes, hepatitis B, genital warts, and HIV/AIDS do not have a cure but can be managed through medication. It's notable that some STIs can be asymptomatic, meaning they do not show symptoms but can still be transmitted to sexual partners.