Sunday, 2 September 2012

Syphilis


Syphilis is a well-known sexually transmitted infection. It is primarily transmitted through sexual contact, although it may also be transmitted from an infected mother to the foetus during pregnancy (congenital syphilis). 

Syphilis is believed to have infected around 15 million people globally, with more than 90% of cases being in the developing world. Despite a decline in infection in the 1940s due to improved availability of penicillin, rates of infection have increased since 2000 which has been attributed to unsafe sexual practices, increased promiscuity, prostitution, and decreasing use of condoms.


Signs and Symptoms


Syphilis is divided into four types: primary, secondary, latent and tertiary. Depending on the type of infection the virus can present with a wide array of signs and symptoms, and may also be mistaken for a variety of other infections not related to syphilis. This can make diagnosis difficult.
Primary syphilis is typically acquired through direct sexual contact with the infectious lesions of another person. It takes 3 to 90 days for the first sign of infection – a skin lesion called a chancre – to appear where contact was made. Despite the appearance as a red, swollen ulceration of up to half a centimetre in size, it is more often than not totally painless, although it may present in a multitude of forms. It then develops in size and type, ranging from a papule-like ulceration to a large skin erosion, and may become painful and tender. In women it is most common for this sort of lesion to develop in the cervix, and in patient with HIV multiple lesions may be present. Lymph node enlargement around the infected area is not uncommon. These lesions tend to last for between three and six weeks without treatment.

Secondary syphilis starts to occur around four to ten weeks after infection. Secondary infection is known for its wide array of manifestations, although most commonly it involves skin, mucous membranes and lymph nodes. A red rash may develop on the trunk and extremities such as the palms and soles of the feet. This rash may become pustular and may also form whitish, flat, wart-like lesions known as condyloma latum. These lesions harbour various types of bacteria and are infectious. Other symptoms may include fever, sore throat, weight loss, hair loss and headaches. Rarely the infection may manifest as more complicated disease such as kidney disease, arthritis and hepatitis. About 25% of people present with recurring acute symptoms of a secondary syphilis infection, although most people recover within six weeks, and most do not report having had primary chancre sores.

Latent syphilis is the type of syphilis that often presents with no symptoms of the disease. It can also be separated in to two distinct categories: early latent syphilis (less than 1 year after secondary syphilis) or late latent syphilis (more than one year after secondary syphilis). In cases of early latent syphilis there may be a relapse of secondary syphilis symptoms, whereas late latent syphilis is asymptomatic.

Tertiary syphilis often develops between 3 and 15 years after the initial infection, and is divided into three distinct forms: gummatous syphilis, late neurosyphilis, and cardiovascular syphilis. The infection is not contagious in the tertiary stage. Without treatment approximately 35% of those infected develop tertiary syphilis. Gummatous syphilis can occur 1 to 45 years after initial infection, and is characterised by the formation of gummas (soft, tumour-like balls of inflammation that vary greatly in size). These gummas can occur anywhere on the body, more commonly on the skin, in bones, and in the liver. Neurosyphilis refers to the infection spreading to the central nervous system. It may occur early, and may be asymptomatic. Symptoms can include poor balance as well as light sensitivity, and in more severe cases of meningovascular syphilis it may cause seizures and dementia. 

Cardiovascular syphilis can occur 10 to 30 years after infection, and can result in syphilitic aortitis and the formation of aneurysms.

Diagnosis and Treatment


Diagnosis of syphilis is generally performed through either blood tests or through direct testing. Blood tests look for particular things in the blood, such as high levels of leukocytes as well as high protein levels, but can return false positives and may require a second round of different blood tests. Direct testing involves a microscopy of a chancre in primary infections, and are time sensitive – needing to be done within 10 minutes of the sample being taken - however as they require specialist equipment and staff that most hospitals do not poses they are rarely performed. Other direct testing, such as fluorescent testing, are not as time sensitive.

Once a diagnosis is confirmed, treatment will vary depending on the stage of the infection. In early infections a single dose of penicillin G or oral azithromycin may be pursued as a first-choice treatment. Doxycycline and tetracycline are secondary choices, but should not be used in pregnant women due to the increased chance of birth defects. Due to antibiotic resistance, a third generation medication has been developed – called ceftriaxone – that may be as effective as penicillin-based treatments.

For later infections more complicated treatments must be pursued. In cases of neurosyphilis large doses of penicillin or ceftriaxone may be given intravenously for a minimum of 10 days. In other types of syphilis, large doses of ceftriaxone, doxycycline or tetracycline may be given for a duration of three to six weeks depending on the medication used. Later stage infections can be treated effectively, but damage already caused by the infection may require alternative and specific treatments

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