Chlamydia trachomatis are microorganisms which are leading cause for sexually transmitted diseases in all parts of the world, including developed countries like the US. The route of transmission of infection is via sexual intercourse. It can affect persons of any age or gender but it produces more symptoms in men, particularly young ones. This is probably because they are more likely to engage in indiscreet sexual activity. Initially, there is a painful urethral discharge, which is more in the morning. This is associated with painful urination. As infection ascends, there is inflammation of the testes, epididymis and prostate. Urinary bladder can be infected due to being in close vicinity, its contamination adding to the pain and discomfort. Anus and rectum can be infected independently in those indulging in anal sex. There may be painful large swellings in the inguinal region, due to involvement of the lymph nodes in the infection. In women, the infection is mostly silent and is diagnosed due to the complications. It can infect the uterine cervix (lower part of uterus) leading to clear or milky white or yellow painless discharge. From here, infection can spread upwards and around the pelvis, causing pelvic inflammatory disease. Due to this, the affected person can suffer from chronic low back pain, lower abdominal pain with or without discharge. After menses, women are more prone to these infections as dampness due to the blood provides a rich media for germs to grow. Fallopian tubes can get infected causing severe pain in lower abdomen. They may get blocked, increasing risk of ectopic pregnancy (where the fertilised egg is implanted outside the uterine wall) and even sterility. Another risk of untreated chlamydia infection is that the individual suffers from conjunctivitis causing redness and mucopurulent discharge from the eyes. This occurs because the eyes can be infected directly by touching with a finger contaminated by the discharge. There can be multiple joint swelling and pain and flat dry rashes over palms and soles. Children suffer from chlamydia infections for no fault of their own. After being contaminated during vaginal delivery, a new born may develop infection of the eyes which can lead to blindness. An older infant can also suffer from infection of the eyes due to his eyes being touched by the contaminated finger of either parent. Apart from this, the new born is at the risk of having pneumonia after birth due to chlamydia infection acquired from the mother’s birth canal. Considering the risks to the baby, centre for disease control and prevention (CDC) has recommended that even with a doubt for chlamydia infection, treatment should be initiated immediately empirically for women. All those infected with chlamydia are at a high risk of acquiring HIV infection. On the other hand, if already immune depressed, they tend to have a more severe form of disease with more risk for complications. Diagnosis is established by isolating the infectious agents from swabs obtained from the genital secretions or lymph node. A culture done, confirms the diagnosis. It has to be differentiated from gonorrhea, another sexually transmitted disease causing similar symptoms. Treatment is by suitable antibiotics given, minimum for a week. Ideally, both partners have to be treated simultaneously to prevent relapse or reintroduction of infection. But treatment given once cures infection at that point of time, but does not prevent it in the future. This should be understood by individuals. For preventing recurrence of infection, a person has to become disciplined in sexual activity and should stick to one partner for life. Good quality condoms used correctly are useful in preventing exposure to chlamydia. Dr Rachna Pande, Specialist, internal medicine rachna212002@yahoo.co.uk