Syphilis is a sexually transmissible infection (STI) caused by the bacteria Treponema pallidum and it can affect both men and women. Syphilis can be classified into Acquired syphilis and congenital syphilis. Routes of transmission for syphilis include sexual activity, pregnancy, drug abuse and blood transfusion.

Several risk factors can increase the possibility of having the disease, include the engagement in unsafe or unprotected sexual practices, being a man who having sex with men, or being an infected person with HIV.

Syphilis progresses through different stages, and its symptoms vary with each stage. These stages reflect the effects of the immune response on the infection and the interaction of the infectious agent with the host.

At the stage of primary syphilis, a single chancre (syphilitic sore) mark may be noticed. At the stage of secondary syphilis, skin rashes and/or mucous membrane lesions (sores in the mouth, vagina, or anus) may be reported along with other symptoms such as mucous patches and warty patches. In the late stages, the disease may cause damage to the brain, nerves, heart, blood vessels, eyes, liver, bones, and joints.

To diagnose syphilis, a physician may perform a physical examination or he may recommend certain blood tests include nontreponemal tests such as RPR (rapid plasma regain) or treponemal tests such as FTA-ABS (fluorescent treponemal antibody absorption).Also, a physician may recommend a swab test or cerebral spinal fluid test.

Speaking of treatment for syphilis, penicillin, which is a popular antibiotic, is considered as the preferred medication at all stages of the disease. If not treated, syphilis can lead to several complications include cardiovascular problems such as aortitis, aneurysms, and neurological problems such as a stroke, hearing loss, dementia, and sexual dysfunction in males.

To prevent syphilis, certain measures can be carried out include, sexual abstinence, using a latex condom, and testing to exclude other sexually transmitted infections. When primary and secondary syphilis diagnosed early, the chances of complete recovery is relatively high.

Syphilis is a sexually transmissible infection (STI) caused by the bacteria Treponema pallidum . The disease starts as a painless sore, typically on the genitals, rectum or mouth. It can affect both men and women and can lead to serious health complications if not adequately treated.

Syphilis can be classified into:

• Acquired syphilis: This type of syphilis can involve :

• Primary syphilis: The incubation period of primary syphilis is range from 9 to 90 days (2-3 weeks) and it results in local infection.
• Secondary syphilis: The incubation period of secondary syphilis is range from 1 to 6 months (6-12 weeks) and it results in generalized infection.
• Early latent syphilis: Some people never develop symptoms over a period of 12-24 months after initial infection.
• Late latent syphilis: Some people never develop symptoms over a period of two years.
• Late symptomatic syphilis (tertiary syphilis): May develop months or years later in about one-third of cases if not treated. Complications may include cardiovascular syphilis, neurosyphilis, gummatous syphilis, Ocular syphilis.

• Congenital syphilis: This type of syphilis occur when syphilis transmits from a mother to her baby through the placenta or during birth. Congenital syphilis can be classified into:

• Early congenital syphilis: Appear within the first two years of life.
• Late congenital syphilis: Appear in children older than 2 years.

Syphilis is a sexually transmitted infections (STI) disease caused by the bacteria Treponema pallidum. When this bacterium reaches broken skin or mucous membranes, it triggers an infection that usually starts with the genitals. Routes of transmission for syphilis include:

• Sexual activity: The infection can be transmitted from person to person during vaginal, oral or anal sex, or by sharing sex toys with an infected person. Syphilis is transmitted by direct contact with a syphilitic sore, known as a chancre. Chancres can develop in several locations including the external genitals, in the vagina, around the anus, in the rectum, or around the mouth.
• Pregnancy: Babies can get the disease from their mothers before they born.
• Drug abuse and blood transfusion: It is possible for injecting drug user to catch the disease by sharing needles with an infected person, or through blood transfusions.

It is unlikely for syphilis to spread by using the same toilet, bathtub, clothing or eating utensils, or from doorknobs, hot tubs or swimming pools.

There are certain risk factors that may increase the risk of having syphilis, include:

• Engagement in unsafe or unprotected sexual practices.
• Sexual engagement with multiple partners.
• Being a man who having sex with man
• Drug abuse, especially cocaine.
• Being an infected person with HIV (the virus that causes AIDS).

Clinical stages of syphilis are primary, secondary, and tertiary stages. These stages reflect the effects of the immune response on the infection and the interaction of the infectious agent with the host. Strong humoral and cell-mediated immune responses are normally provoked early in the course of infection.

During the primary stage of syphilis, the chancre, begins as a small macule, enlarges to a papule, which seems to be a local tissue reaction found at the site of contact. Spreading of organisms from the site of infection via the lymphatics to the blood occurs within a few hours and lymphadenopathy and splenomegaly emerge as the early immune responses due to the hyperplasia associated with induction of specific immunity.

During the secondary stage, there are subsequent tissue reactions to the infection, which are similar to many reactions caused by invasions of bacterial pathogens .The bacteria rapidly grows and multiplies resulting in the characteristic rash of secondary syphilis and the patients is considered highly infectious during this stage.

During the tertiary stage, the infection becomes highly dangerous and concentrated, and it is can attack almost every part in the body including the bones, the heart, the throat, and the skin. Bacteria invade organs throughout the body producing a characteristic soft gummy lesion called “gumma”.

The toxicity of the bacteria attacks the epiphyses of the long bones, especially, bones of the upper extremities. It is expected for those who go untreated to die within five years of the onset of the tertiary stage and they are susceptible to show the first signs of general paralysis of the insane (GPI).

However, many syphilis infected individuals who develop GPI never become outright insane, although the disease has the capacity to changes their patterns of behavior by changing certain processes in their brains.

Syphilis progresses through different stages, and symptoms vary with each stage. However, the stages may overlap, and symptoms may appear in different patterns. Stages and symptoms of syphilis include:

• Primary syphilis: This stage is featured by the appearance of a single chancre (syphilitic sore) mark, but there may be multiple chancres. The chancres usually develop about three weeks after exposure and they mostly characterized by being firm, round, and painless. The chancres will heal on their own within three to six weeks, also, many people do not report the chancre because it is usually painless, and it is difficult to be noticed because it may be hidden within the vagina or rectum. However, enlarged lymph nodes in the area of the sore may be reported at this stage.
• Secondary syphilis: This stage is featured by the appearance of skin rashes and/or mucous membrane lesions (sores in the mouth, vagina, or anus).The symptoms at this stage start 4 to 8 weeks after the primary syphilis and it may include :

• Skin rash: This rash is usually not itchy and can spread on the palms of the hands and soles of the feet. The rash mainly begins on the trunk but eventually covers the entire body.
• Sores called mucous patches in or around the mouth, vagina, or penis.
• Moist, warty patches (called condylomata lata) in the genitals or skin folds.
• Loss of appetite and weight loss
• General ill feeling and fatigue
• Vision changes and headaches
• Muscle and joint pain
• Swollen lymph nodes
• Fever
• Less common symptoms at this stage include

1. Patchy alopecia (hair loss)
2. Anterior uveitis (inflammation of the anterior part of the eye)
3. Cranial nerve palsies (lack of function of a nerve)
4. Hepatitis
5. Meningitis
6. Enlarged spleen
7. Glomerulonephritis (inflammation of the tiny filters in the kidneys).

• Latent syphilis: At this stage, people become asymptomatic with no visible signs or symptoms of syphilis.
• Tertiary Syphilis: In the late stages, the disease may cause damage to the brain, nerves, heart, blood vessels, eyes, liver, bones, and joints. Tertiary syphilis is uncommon and develops in a subset of untreated syphilis infections. The symptoms vary widely and depend on which organs have been affected. Symptoms may include:

• Damage to the heart, resulting in aneurysms or valve disease.
• Neurosyphilis, resulting in a headache, altered behavior, difficulty coordinating muscle movements, paralysis, sensory deficits, and dementia. Moreover, Syphilis can invade the nervous system as well as any eye structure at any stage of infection.
• Ocular syphilis, resulting in vision changes, decreased visual acuity, and permanent blindness.
• Tumors of skin, bones, or liver.

Visualizing the Treponema pallidum bacterium via darkfield microscopy is widely known to be the conclusive diagnostic test for syphilis. However, this method is rarely performed today. To diagnose syphilis, a physician may recommend:

• Physical examination: A careful examination for genitals (and inside the vagina for women) or for other parts of the body will be performed by a healthcare professional to detect suspicious growths or rashes that may be caused by syphilis.
• Blood test: The results of blood test can tell whether a patient have syphilis or have had it in the past. If the test show negative results, the physician may recommend the patient to repeat the test a few weeks later, in case it was too early to give an accurate result. There are two types of blood tests available for syphilis :

1. Nontreponemal tests: This type of tests is mainly used for screening and it is known widely to be simple and inexpensive. However, these tests are insufficient for diagnosis because they are not specific for syphilis and can produce false-positive results. Nontreponemal tests include:

• RPR (rapid plasma reagin): This test is helpful in monitoring treatment for syphilis in addition to screening the disease. This test measures the levels (titer) of antibodies in the blood.
• VDRL (Venereal Disease Research Laboratory): This test is useful in diagnosing neurosyphilis when performed on CSF (cerebrospinal fluid).

1. Treponemal tests: This test is helpful in detecting antibodies that are specific for syphilis. Treponemal antibodies can be detected earlier than nontreponemal antibodies and usually remain detectable for life. Treponemal antibody tests include:

• FTA-ABS (fluorescent treponemal antibody absorption): This test is helpful after the first 3-4 weeks following exposure and it can be used to diagnose neurosyphilis by measuring antibodies to T. pallidum in the CSF.
• TP-PA (T. pallidum particle agglutination assay): This test is preferred over FTA-ABS because it is more precise and fewer mistakes.
• MHA-TP (Microhemagglutination assay): This is another method, which used to verify the results. However, this test is less common applied these days.
• Immunoassays (IA): Noticeable number of automated immunoassays tests have been developed and proved to be efficient for syphilis screening.

• Swab test: This test is performed by taking a small sample of fluid from any sores and send it to the laboratory to look for syphilis. Swab tests may include:

1. Darkfield microscopy--This method is helpful in the early stages of syphilis when a suspected syphilis sore (chancre) is present. This method uses a special instrument called a dark-field microscope to examine a sample of the sore.
2. Molecular testing (polymerase chain reaction, PCR): This test is primarily used to examine a sample from the sore, in blood, or in CSF to detect genetic material from the bacteria.

• Cerebral spinal fluid test: A physician may recommend a procedure called a lumbar puncture (spinal tap) if syphilis led to certain nervous system complications. A lumbar puncture is performed by collecting a sample of cerebrospinal fluid.

It is easy to treat syphilis when diagnosed at early stages. Penicillin is considered as the preferred antibiotic medication at all stages. Penicillin is administered in different doses and shapes, including:

• Benzathine penicillin G is the standard treatment for adults and adolescents with primary, secondary, or early latent syphilis, and it is usually administered as 2.4 million units intramuscularly in a single dose.
• Benzathine penicillin G  is the standard treatment for adults and adolescents with late latent syphilis or latent syphilis of unknown duration, and it is usually administered as  7.2 million units total in 3 doses of 2.4 million units intramuscularly each at weekly intervals.
• Acqueous crystalline penicillin G is the standard treatment for neurosyphilis and ocular syphilis, and it is administered as 18-24 million units per day, it is given as 3-4 million units intravenously every 4 hours or continuous infusion, for 10-14 days.

Treating syphilis with antibiotics may result in several side effects, including fever, headaches, muscle and joint pain.

Syphilis can lead to several complications that may include:

• Cardiovascular problems such as aortitis, aneurysms, and heart valves problems.
• Neurosyphilis and neurological problems such as a stroke, hearing loss, dementia, sexual dysfunction in men, bladder incontinence, lightning-like pains, visual problems, loss of pain and temperature sensations, and syphilitic meningitis.
• HIV infection due to the fact that a syphilis sore can bleed easily, facilitating HIV to enter the bloodstream during sexual activity.
• Syphilitic myelopathy , which involves muscle weakness and abnormal sensations.
• Small bumps or tumors (gummas) which develop in the late stage of syphilis, on the skin, bones, liver or any other organ.
• In pregnant women, untreated syphilis can cause stillbirth (babies who are born dead) or infant death soon after birth.

Preventive measures to help prevent syphilis may include:

• Sexual abstinence: Forgo having sex is the only certain way to avoid syphilis.
• Monogamous relationship: Having a mutually monogamous sexual relationship with one partner who is uninfected will certainly prevent syphilis.
• Avoid sharing sex toys: It is advisable to wash and cover sex toys with a condom before sharing them.
• Using of latex condom: Using condoms can reduce the risk of contracting syphilis by covering the syphilis sores.
• Using of dental dams (a square of plastic) during oral sex.
• Avoid recreational drugs: Excessive consumption of alcohol or other drugs can affect right decision making and can lead to unsafe sexual practices.
• Screening for pregnant women: To identify infected mothers, a routine blood test for syphilis is done during pregnancy to reduce the risks of developing syphilis in the infant by giving earlier treatment for the mothers.
• Testing to exclude other sexually transmitted infections is advisable.

When primary and secondary syphilis diagnosed early, the chances of complete recovery is relatively high. Secondary syphilis usually goes away within weeks, however, in some cases it may last for up to 1 year. Late complications of syphilis appear in up to one-third of people who get no treatment. Late syphilis may cause permanent disability, and eventually, it may lead to death.

Many infants who are infected with syphilis at the early stages of pregnancy are stillborn. Decreasing the risk of congenital syphilis can be done by treating the expectant mothers. A better outlook has been reported in babies who become infected when passing through the birth canal.

The following are syphilis related facts gathered from different resources:

• According to World Health Organization (WHO) publications, each year, there are estimated 5.6 million new cases of syphilis, and the disease is responsible for infecting over 5% of sex workers in 37 countries around the world. In addition, in 2012, over 900 000 pregnant women were infected with the disease resulting in approximately 350 000 adverse birth outcomes including stillbirth.
• According to Centers for Disease Control and Prevention (CDC), in 2015, a total of 23,872 cases of primary and secondary syphilis (7.5 cases per 100,000 population) were reported in the United States. This rate represents a 19.0% increase compared with 2014.
• According to the European Centre for Disease Prevention and Control, in 2014, a total of 24 541 cases of syphilis (5.1 per 100 000 population) were reported in 29 EU/EEA Member States except for Austria and Liechtenstein. Reported syphilis rates were six times higher in men than in women.
• Results of a systematic review of all available data on syphilis prevalence in 23 countries in the Middle East and North Africa have been published in Sexually Transmitted Infections journal, and it is calculated prevalence levels of syphilis among female sex workers as (1% - 87%), male sex workers as (4%–63%), men who have sex with men as (4%–60%), and injecting drug users as (1%–18%).
• According to data mentioned in a study published in Emerging Health Threats Journal, in China, from 2000 to 2005, the incidence of syphilis averaged 5.1 to 5.8 per 100,000 per year.