Chlamydiae are intracellular bacteria. They   produce a spectrum of illness ranging from asymptomatic infections to frank disease.  Infections by Chlamydia trachomatis are the leading cause for sexually transmitted diseases in all parts of the world, including developed countries.The route of transmission of infection is sexual.  It can affect persons of any age or gender but it produces more symptoms in men, particularly young ones.  This is probably because men particularly young ones may engage more in indiscreet sexual activity. Initially in the sickness, there is a painful urethral discharge, which is more in the morning before voiding of the bladder.  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 contamination adding to the pain and discomfort.  The anus and rectum can be infected independently in those indulging in anal sex.  In case of infection by Lymphogranuloma venereum, a strain of Chlamydia, there is painful large swellings in the inguinal region known as "inguinal bubo”.In women, the infection is mostly silent and is diagnosed due to the complications. It can infect the uterine cervix leading to clear or whitish yellow painless discharge. From here, infection can spread upwards and around   causing pelvic inflammatory disease.  Due to this, the patient can suffer from chronic low back pain, lower abdominal pain with or without discharge. After menses women are more prone to these infections as blood provides a rich media for germs to grow. Fallopian tubes can get infected causing severe pain in the lower abdomen.  They may get blocked, increasing chances of ectopic pregnancy. Both men and women are at the risk for developing sterility due to blockade tubes caused by untreated Chlamydia infection. Another risk of untreated infection is development of Reiter’s syndrome. In this the individual suffers from conjunctivitis (inflammation of conjunctiva of the eyes) causing redness and mucopurulent discharge, multiple joint swelling and pain and flat dry rashes over the palms and soles. Eyes can also be infected directly because of being touched by a contaminated finger leading to conjunctivitis.Children suffer from Chlamydia infections for no fault of their own. After being contaminated during delivery, a new born may develop infection of the eyes (opthalmia neonatorum) 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 infection acquired from the mother’s birth canal. 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 the disease with more risk for complications. iagnosis is established by isolating the infectious agents from swabs obtained from the genital secretions or lymph nodes and culture.  It has to be differentiated from gonorrhea, another sexually transmitted disease causing similar symptoms.Treatment is by suitable antibiotics given for a week. In case of persistence of symptoms or infection with lymphogranuloma venereum, treatment is sometimes given for three weeks to prevent relapse. Ideally both partners have to be treated simultaneously to prevent re introduction of infection.But treatment given once does not protect one from re infection.  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 also useful in preventing exposure to Chlamydia. Dr Pande is a specialist internal medicine-Ruhengeri Hospital