Emerging Sexually Transmitted Diseases: Symptoms & Diagnosis

In a recent publication in Disease-a-Month, Catherine F. Decker, MD, from Walter Reed National Military Medical Center, Bethesda, Maryland, discussed some infections that have recently emerged as important sexually transmitted diseases (STDs)—in particular, hepatitis C, lymphogranuloma venereum (LGV), and Mycoplasma genitalium infections.

Hepatitis C is a viral liver disease caused by the blood-borne hepatitis C virus (HCV). HCV is transmitted mainly through blood exposure and was originally not thought to be efficiently transmitted through sexual intercourse. However, data in recent years have shown that sexual transmission of HCV can occur, especially among human immunodeficiency virus (HIV)-infected men who have sex with men (MSM).

Acute HCV infection may be difficult to recognize because it produces few or no symptoms. Most infected individuals go on to develop chronic HCV infection, which ultimately results in liver injury. But, because these people are usually asymptomatic, their infection often goes undetected and they continue to represent a source of transmission to other individuals.

HCV testing recommendations are based on either the risk for HCV infection or a recognized exposure. This includes screening in all people born during 1945 to 1965, as well as in those born to a mother with HCV infection or who have a history of current or past injection drug use. Testing should be performed using a US Food and Drug Administration (FDA)-cleared test for antibody to HCV. In cases of a positive antibody result, nucleic acid amplification testing (NAAT) is also necessary to detect the presence of HCV ribonucleic acid (RNA) to confirm the diagnosis of current HCV infection. “Because some HIV-infected patients fail to develop HCV antibodies, HCV RNA testing should be performed in patients with unexplained liver disease who are anti-HCV negative, writes Dr. Decker. “The course of liver disease is more rapid in HIV/HCV co-infected persons, and the risk for cirrhosis is nearly twice that of persons with HCV infection alone.”

Although HCV is rarely transmitted sexually, the Centers for Disease Control and Prevention (CDC) does recommend the use of condoms by individuals who have multiple sexual partners, especially those who also have HIV infection. However, the CDC suggests that condom use by monogamous couples might not be necessary.

According to Dr. Decker, LGV is another uncommon STD. It is caused by 3 unique strains (serovars L1, L2, or L3) of Chlamydia trachomatis. Among heterosexual individuals. LGV typically manifests as a genital lesion, such as an ulcer or papule, and regional inguinal and/or femoral lymphadenopathy. However, in MSM, it may manifest as severe proctocolitis that can resemble inflammatory bowel disease. Symptoms in MSM include bloody rectal discharge, and may be associated with tenesmus, colorectal strictures or fistulas, and pain.

Although diagnosis of LGV is based predominantly on clinical findings, NAAT on specimens from the affected area (rectal or lesion swabs) is preferred for confirmation. Individuals in whom LGV is suspected should be presumptively treated for the disease—usually with a doxycycline-based regimen. Suspected cases of LGV should also be reported to the state health department. Sexual partners of infected individuals should also be examined, tested, and treated for LGV if they engaged in sexual contact with the individual within 2 months before the onset of symptoms.

M. genitalium is also an emerging cause of sexually transmitted infections in men and women. It is recognized as an important cause of about 25% of cases of non-gonococcal urethritis in men. M. genitalium is also associated with cervicitis, pelvic inflammatory disease (PID), infertility, and preterm delivery in women; infections in women are also often asymptomatic.

Diagnosis of M. genitalium is also based mainly on clinical findings. Because culture of M. genitalium can take up to 6 months, NAAT (on urine samples, or urethral, vaginal, and cervical swabs) is preferred for confirmation of infection. However, NAAT for this organism is not yet widely available. As a consequence, treatment of M. genitalium infection typically occurs in a syndrome-based approach to the management of the patient’s symptoms.

For urethritis, azithromycin has been shown to be more effective than doxycycline, although resistance to azithromycin is rapidly emerging. Dr. Decker also notes that “[r]ecommended PID treatment regimens are based on antibiotics that are not effective against M. genitalium. Therefore, clinicians might consider M. genitalium in cases that do not respond to therapy within 7 to 10 days.” Moxifloxacin has been successfully used to treat M. genitalium in men and women with previous treatment failures—in particular in those who experience persistent symptoms and in whom infection is confirmed, concludes Dr. Decker.

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.