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.
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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