Sexually transmitted infections

Infections and reproductive health

An infection that passes from one person to another through sexual intercourse is a sexually transmitted infection (STI). Older books call it a venereal disease (VD), and some call it a reproductive tract infection (RTI).

Anyone can get one, and there is no shame in asking for care. A person who gets care early is helped, and so are the people around him or her.

The infections in the NCERT list

NCERT names these common STIs: gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, trichomoniasis, hepatitis-B and HIV, which leads to AIDS.

This part is not in the NEET syllabus, but A-Level and IB ask it. The causes in the table come from standard medical books. NCERT does not name them in this chapter.

The table has two messages.

• Cause. Some STIs are caused by bacteria, one by a protozoan and some by viruses. Gonorrhoea, syphilis and chlamydiasis are bacterial. Trichomoniasis is caused by a protozoan. Genital herpes, genital warts, hepatitis-B and AIDS are viral.
• Cure. NCERT says that, except for hepatitis-B, genital herpes and HIV, the others are completely curable if they are detected early and treated properly.

Other ways of spread

Hepatitis-B, genital herpes and HIV do not pass only through sexual contact. They can also pass by

• sharing injection needles and surgical instruments with an infected person,
• the transfusion of infected blood, and
• an infected mother to her foetus.

Why they are found late

The early signs of most of these infections are small: itching, a fluid discharge, slight pain or swelling in the genital region. In females, there may be no sign at all, so the infection may stay undetected for a long time. Fear of social stigma also stops people from seeking care.

An untreated infection can lead to serious problems later:

• pelvic inflammatory disease (PID),
• abortions and stillbirths,
• ectopic pregnancies,
• infertility, and
• cancer of the reproductive tract.

Prevention

NCERT lists simple steps.

• Avoid sex with unknown partners or with multiple partners.
• Always use condoms during coitus.
• Go to a qualified doctor in case of doubt, for early detection and complete treatment.

Because the other ways of spread exist, a person should not share needles or razors, and blood for a transfusion must be tested. Vaccines exist for hepatitis-B and for the human papillomavirus. For every infection, early care gives the best result.

This part is not in the NEET syllabus, but A-Level and IB ask it. Public health workers use models to show how a risk adds up. The simulation below is such a model. Its numbers are made up, so do not read it as data for any infection.

You should find that even a small chance in one exposure becomes a large chance after many exposures, and that a condom used each time brings it down a great deal.

Try it in Python

The program stores the eight infections in a dictionary. It counts them by cause and finds the ones that are not completely curable.

Practise with new numbers

Common mistakes

• Saying that all STIs are completely curable. Hepatitis-B, genital herpes and HIV are not.
• Saying that STIs spread only by sexual contact. Hepatitis-B, genital herpes and HIV also spread by needles, blood and from mother to foetus.
• Thinking that no signs mean no infection. Females in particular may have no sign for a long time.
• Thinking that other methods protect. The pills and the IUDs prevent a pregnancy, but they do not protect against an infection. A condom does.
• Thinking that a person is cured when the signs go. The doctor must say that the treatment is complete.

Remember these

• STI, also VD or RTI: gonorrhoea, syphilis, genital herpes, chlamydiasis, genital warts, trichomoniasis, hepatitis-B and HIV.
• Except for hepatitis-B, genital herpes and HIV, the others are completely curable if detected early.
• Hepatitis-B, genital herpes and HIV also spread by needles and instruments, by blood, and from mother to foetus.
• Complications: PID, abortions, stillbirths, ectopic pregnancies, infertility and cancer of the reproductive tract.
• Prevention: avoid unknown and multiple partners, always use condoms, and see a qualified doctor early.

Check yourself

Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.

1. What do the letters STI stand for? Name two other terms for the same thing.

2. Which three infections of the NCERT list are not completely curable?

3. In what other ways can these three infections spread?

4. Why can a female have an infection for a long time without knowing?

5. What three steps does NCERT list for prevention?

References

• NCERT (2023). Biology, Textbook for Class XII, chapter 3, Reproductive Health.
• World Health Organization (2021). Global progress report on HIV, viral hepatitis and sexually transmitted infections, 2021.
• Betts J. G. et al. (2022). Anatomy and Physiology 2e, OpenStax, chapter 27, section on sexually transmitted infections.