syphilis - causes, symptoms, diagnosis and treatment

Medically Reviewed by Dr Sravya, MBBS, MS 


The STI known as syphilis is caused by the bacterium Treponema pallidum. It is an extremely infectious disease that, if neglected, could have detrimental effects on your health. While it usually spreads through sex, syphilis can also pass from mother to foetus while a woman is pregnant. There are four stages of infection progression: primary, secondary, latent, and tertiary. A painless sore or ulcer develops at the infection site during the first stage, which frequently goes unreported.


Rashes, fever, and enlarged lymph nodes are examples of secondary-stage symptoms. If left untreated, the infection can develop into latent and tertiary stages, which could seriously harm various organs, such as the heart and brain. Blood tests, such as the VDRL and treponemal assays, are used in the diagnosis to look for antibodies or the bacterium itself. Fortunately, medications like penicillin can effectively treat syphilis, especially if it is caught early. Safe sexual behaviour and routine STI testing are crucial for prevention.

Table of Contents

Syphilis causes


1). Microbial Infection:

Treponema pallidum, the bacteria that causes syphilis, can enter the body through cuts, mucosal membranes, or direct contact with sores that are already infected.

2). Sexual Contact:

Person is the main method of transmission. Small cuts or abrasions are entry points for the germs into the body.

3). Unprotected Sex:

Syphilis transmission is more likely to occur when sexual activity is conducted without the use of a condom. A barrier created by condoms can lessen the possibility of coming into contact with wounds that are infected.

4). Direct Contact with Sores:

The germs can be transmitted through contact with syphilis sores or chancres on the genitalia, mouth, or rectum of an affected individual.

5). Transmission from Mother to Child:

Congenital syphilis can develop when syphilis-positive pregnant women transmit the infection to their unborn child during pregnancy or childbirth.

6). Sharing Needles:

Syphilis can also be shared by exchanging needles or other drug paraphernalia with an infected individual because the bacteria can be found in blood.

7). Close Personal Contact:

Syphilis can also be spread through intimate personal contact with an infected individual, such as kissing if there are any open sores present, however, this is less usual.

8). Asymptomatic Carriers:

Despite not having any symptoms, some syphilis sufferers might still spread the illness to others through intercourse.

9). Various Partners:

Multiple sexual partners raise the danger of coming into contact with infected people and the chance of getting syphilis.

10). Immunodeficiency:

Due to their decreased ability to fight off infections, people with weakened immune systems, such as HIV/AIDS, are more likely to get syphilis.

Primary syphilis symptoms

Certainly, the following list of syphilis symptoms is organized by stage:


(i) Primary stage

(ii) Secondary stage

(iii) Latent stage

(iv) Tertiary stage

1). Primary stage:

A painless sore or ulcer known as a cyst develops at the injection site (genitals, mouth, or anus).

– The cartilage is usually round and solid, and it heals within a few weeks.

2). Secondary Stage:

(i)  The palms and soles of the feet are just two body parts where a rash may appear.

(ii)  Flu-like symptoms, such as fever and swollen lymph nodes, might also manifest.

(iii)  The rash may come and go and does not itch.

3). Latent stage:

(i) There are no visible signs of this period.
(ii) The infection is still present in the body but is not showing any symptoms.

4). Late Tertiary Stage:

(i) Years after the first infection, if the infection is not treated, it may develop into tertiary syphilis.
(ii) Serious complications, including harm to vital organs like the heart, brain, nerves, and blood vessels, can result from this stage.
(iii) Muscle coordination issues, paralysis, numbness, blindness, and dementia are possible symptoms.

A sexually transmitted infection called syphilis is caused by the bacterium Treponema pallidum. Clinical assessment, laboratory testing, and study of the patient’s medical history are frequently used to make the diagnosis. An overview of the diagnostic procedure is given below:

Syphilis diagnosis


(i) Serological tests

(ii) Dark Field microscopy

(iii) Polymerase chain reaction (PCR)

(iv) Clinical evaluation of symptoms

(v) Screening during pregnancy

1). Clinical Examination:

To check for any syphilis symptoms or signs, a healthcare professional will review the patient’s medical history, including sexual history. Each stage of syphilis has its own unique set of symptoms.

2). Serological Tests:

Laboratory examinations are essential for syphilis diagnosis. They look for antibodies that the body makes in response to an infection. The most popular serological tests are as follows:

(i) Non-Treponemal Tests: These evaluations, for example: Venereal Disease Research Laboratory (VDRL) and Rapid Plasma Regain (RPR) tests, look for antibodies that react with cardiolipin, a type of lipid found in cells. These tests are helpful for initial screening, but they could produce false positive results, needing more testing to be validated.

(ii) Treponemal Tests: Tests like the enzyme immunoassay (EIA) and the Treponema pallidum particle agglutination (TP-PA) directly identify antibodies against T. pallidum. These tests are the testing to confirm the infection’s existence.

3). Confirmatory Tests:

Additional tests are frequently performed to confirm the diagnosis and differentiate between present and previous infections if the preliminary tests are positive.

These tests may include the T. pallidum hemagglutination assay (TPHA) and the Fluorescent Treponemal Antibody Absorption (FTA-ABS) test.

4). Cerebrospinal fluid (CSF) examination (if required):

If neurosyphilis (syphilis affecting the neurological system) is suspected, a CSF test may be carried out to check for abnormalities in cell count, protein levels, and the presence of antibodies.

5). Dark-Field Microscopy (rare):

A sample from a syphilis sore may occasionally be studied using dark-field microscopy in order to directly see the presence of Treponema pallidum bacteria. This is most common during the initial stage.

Syphilis treatment

Syphilis treatment definitely differs depending on the disease’s various stages. The various methods of therapy are listed below for each stage


(i) Antibiotics
(ii) Treatment based on disease stage and duration
(iii) Follow-up testing to ensure treatment success
(iv) Partner notification and treatment
(v) Routine sexual health check-ups

1). Primary and secondary syphilis:

Treatment: The suggested course of treatment involves a single intramuscular injection of benzathine penicillin G. When syphilis is in its early stages, this treatment is very successful.

Alternative: Doxycycline or tetracycline may be used as an alternative for those who are allergic to penicillin.

2). Early latent syphilis (infection lasting less than a year):

Medication: Similar to primary and secondary syphilis, benzathine penicillin G is normally administered intramuscularly only once.

3). Late Latent Syphilis (infection staying longer than a year):

Treatment: A series of injections with benzathine penicillin G may be necessary for people who have late latent syphilis or latent syphilis of uncertain duration.
Depending on how long the latent infection has been present, the healthcare provider will decide the number of injections to administer.

4). Tertiary Syphilis, which also includes neurosyphilis:

Medication: Tertiary syphilis often requires a longer treatment course due to its more serious effects. For 10 to 14 days, daily intravenous doses of penicillin G may be required. Usually, this intense therapy is needed to cure neurosyphilis, which damages the nerve system.

5). Congenital syphilis (an illness that is passed from mother to foetus):

Medication: Penicillin is the recommended treatment for syphilis in pregnant women to stop the disease from spreading to the foetus. In accordance with their symptoms and test findings, newborns with congenital syphilis are also treated with penicillin. It’s crucial to remember that the treatment strategy is founded on suggestions and guidelines from medical organisations, and the choice of treatment can change depending on circumstances specific to each patient. Regular follow-up and serological testing are also necessary to check the treatment response and make sure the infection has been well treated.


In conclusion, syphilis is a potentially serious sexually transmitted infection that is alarming. Early detection and intervention are essential to halting the disease’s course, which can result in serious health problems. Symptoms of syphilis may appear in phases, beginning with numb sores and escalating to rashes and systemic signs and symptoms. Blood tests that look for certain antibodies or the presence of the bacteria Treponema pallidum are frequently necessary for an accurate diagnosis. Fortunately, syphilis can be effectively treated with antibiotics like penicillin, especially when it is in its early stages. In addition to curing the infection, prompt treatment also helps to avoid long-term consequences. Safe sex practices and routine STI screenings are critical for your own and your partners’ protection, especially if you engage in high-risk behaviour. Syphilis is a disease that can be prevented and treated; however, its management and eradication depend on public awareness, early detection, and adequate medical care.