GUM - Viral STIs Flashcards
What is herpes simplex virus?
There are two strains of the herpes simplex virus (HSV) in humans: HSV-1 and HSV-2. Whilst it was previously thought HSV-1 accounted for oral lesions (cold sores) and HSV-2 for genital herpes it is now known there is considerable overlap.
What symptoms does HSV cause?
- primary infection: may present with a severe gingivostomatitis
- cold sores
- painful genital ulceration (cf. syphilis where lesions are non painful)
How is HSV infection managed?
gingivostomatitis: oral aciclovir, chlorhexidine mouthwash
cold sores: topical aciclovir although the evidence base for this is modest
genital herpes: oral aciclovir. Some patients with frequent exacerbations may benefit from longer term aciclovir.
Salt water bathing is also useful.
How should HSV be managed during pregnancy?
Elective caesarean section at term is advised if a primary attack of herpes occurs during pregnancy at greater than 28 weeks gestation.
Women with recurrent herpes who are pregnant should be treated with suppressive therapy and be advised that the risk of transmission to their baby is low.
What virus causes genital warts?
Genital warts (also known as condylomata accuminata) are a common cause of attendance at genitourinary clinics. They are caused by the many varieties of the human papilloma virus HPV, especially types 6 & 11. It is now well established that HPV (primarily types 16,18 & 33) predisposes to cervical cancer.
How do genital warts present?
Small (2 - 5 mm) fleshy protuberances (cauliflower appearance) which are slightly pigmented
May bleed or itch
How are congenital warts managed?
- topical podophyllum or cryotherapy are commonly used as first-line treatments depending on the location and type of lesion. Multiple, non-keratinised warts are generally best treated with topical agents whereas solitary, keratinised warts respond better to cryotherapy
- imiquimod is a topical cream which is generally used second line
- genital warts are often resistant to treatment and recurrence is common although the majority of anogenital infections with HPV clear without intervention within 1-2 years
How is hepatitis B transmitted?
Hepatitis B is a double-stranded DNA hepadnavirus and is spread through exposure to infected blood or body fluids, including vertical transmission from mother to child. The incubation period is 6-20 weeks.
What are the clinical features of hepatitis B infection?
Features of hepatitis B include fever, jaundice and elevated transaminases (AST and ALT). Remember, transaminases are located in hepatocytes and are released following cell damage. ALP and GGT are found in duct epithelium and are usually raised first following obstruction.
The illness tends to start insidiously, with fever and anorexia. Jaundice (darkening of urine and lighter stools) is only seen in 10% of patients. Majority are detected by deranged LFTs.
What are the complications of hepatitis B infection?
chronic hepatitis (5-10%) fulminant liver failure (1%) hepatocellular carcinoma glomerulonephritis polyarteritis nodosa cryoglobulinaemia
Which groups are at risk of hepatitis B infection and should be immunised?
At risk groups who should be vaccinated include: healthcare workers, intravenous drug users, sex workers, close family contacts of an individual with hepatitis B, individuals receiving blood transfusions regularly, chronic kidney disease patients who may soon require renal replacement therapy, prisoners, chronic liver disease patients.
Most schedules give 3 doses of the vaccine with a recommendation for a one-off booster 5 years following the initial primary vaccination.
What factors suggest a poor response to hepatitis B vaccine?
Around 10-15% of adults fail to respond or respond poorly to 3 doses of the vaccine. Risk factors include age over 40 years, obesity, smoking, alcohol excess and immunosuppression.
What is HBsAg? What does its presence imply?
Hepatitis B surface antigen (HBsAg) is a surface protein found in excess in hepatitis B and circulates in the blood. It is the first marker to appear in acute hepatitis infection and causes the production of anti hepatitis B surface antibodies (anti-HBs).
HBsAg normally implies acute disease (present for 1-6 months). If HBsAg is present for longer than 6 months then this implies chronic disease (i.e. infective).
The key thing to remember is that HBsAg = ongoing infection, either acute or chronic (if longer than 6 months).
What does the presence of anti-HBs suggest?
The presence of anti hepatitis B surface antigen antibodies suggests immunity (either exposure or immunisation). If exposure is from previous infection then anti-HBc are also present. If from vaccination, anti-HBc is not present. It is negative in chronic disease.
What is anti-HBc?
The hepatitis B core antigen (HBcAg) is not found in the blood but antibody to it (anti-HBc) appears early in illness. Anti-HBc is initially IgM type, with IgG appearing later and persisting.
Anti-HBc = caught, i.e. negative if immunised