Syphilis is a bacterial infection caused by the spirochete Treponema pallidum, and is considered a
sexually-transmitted disease. Syphilis is readily treatable with penicillin, but if left untreated,
it may cause severe damage to most bodily organs and can be life-threatening. Syphilis is known as
“the great imitator”, as it mimics a large number of different conditions. Syphilis
patients are at increased risk of contracting HIV. Transmission is mainly through sexual contacts,
but infection may also spread from mother to child during pregnancy,
via blood transfer, and non-sexual direct contacts with infected skin lesions.
Previous infection does not provide immunity and patients who have been cured can catch the
disease again if exposed to an infected person. Syphilis develops in 3 symptomatic stages:
primary, secondary and tertiary, which are typically separated by periods of no symptoms.
There is also a prominent latent phase in between secondary and tertiary syphilis.
The disease is highly contagious during primary and secondary stages,
and may remain contagious into early latent phase. The average time from exposure to developing
symptoms is 3 to 4 weeks. Primary syphilis typically presents with a single,
painless, firm open sore, called a chancre, at the site of direct contact with the infected lesion.
The chancre usually heals spontaneously after a few weeks, and may go unnoticed in many patients.
Without treatment, however, the bacteria spread to the bloodstream and the disease
progresses to the second stage, characterized by a body-wide rash. This typically occurs a
few weeks after the chancre heals, but it may also overlap with the first stage in
some patients, who still have the chancre. The rash is usually prominent in the palms
or soles, and not itchy. Patients may also have fever, swollen lymph nodes, and wart-like sores
in moist areas of the skin. Less common symptoms include macular rash, headache, sore throat,
jaundice, and hair loss. The symptoms usually resolve without treatment within a few weeks,
but some people may have it come and go for up to a year.
Following the secondary stage is the latent phase that may last for years, during which
time the bacteria remain dormant and there are no symptoms, but tests for syphilis are positive.
This stage is generally not contagious, but lesions may sometimes appear on the
skin or mucous membranes, and direct contacts with these lesions can transmit the disease.
Tertiary syphilis develops in about a quarter of untreated cases,
years or decades after the original infection. There are three major forms: gummatous syphilis,
cardiovascular syphilis, and neurosyphilis. Gummatous syphilis is characterized
by the presence of soft lumps of inflammatory tissues called gummas,
which can infiltrate and destroy any organ. Cardiovascular syphilis affects the aorta
and heart valves, causing aortic aneurysm and aortic valve disease.
Neurosyphilis can manifest as a number of problems in the nervous system: from meningitis, seizures,
stroke, to hearing loss, visual impairment, speech disorder, dementia and other mental disorders.
Pregnant women with syphilis may spread the disease to their child through the placenta, or
via contacts with infected lesions during birth. Congenital syphilis can cause miscarriage, still
birth, or birth defects in the newborns. Some neonates with congenital syphilis are asymptomatic
at birth, but develop symptoms within a couple of years, before entering the latent stage.
Diagnosis is by serological tests for antibodies against the bacteria,
in blood or cerebrospinal fluid samples. Dark-field microscopy
may be used to visualize spirochetes from chancre exudates or lymph node aspirates.
Most syphilis cases can be treated with penicillin.
Earlier stages require only a single injection. Additional injections are needed for later stages.
Some other antibiotics may be used for non-pregnant patients who are allergic to
penicillin. Pregnant women with penicillin allergy should undergo desensitization
so they can be treated with penicillin. Patients may experience a reaction,
known as Jarisch-Herxheimer reaction (JHR), in the first day of treatment.
The reaction usually subsides within 24 hours, but patients must be warned and observed.