A spirochete bacteria that causes syphilis

The U.S. STI Epidemic Shows no Signs of Slowing. Syphilis Cases Have Increased by 2,250%

STI’s are a significant public health problem in the United States. Every year, an estimated 27 million1,5 new sexually transmitted infections are reported to the Centers for Disease Control and Prevention (CDC) in the United States at a cost of $16 billion in direct medical costs. Fifteen- to twenty-four-year-olds account for half of all new STI infections.3 In 2021, STI’s reached record breaking levels and they continue to increase year to year.2

Among reported STI’s, syphilis continues to climb at an alarming rate. According to a new 2023 report by the CDC, “The United States is currently experiencing a syphilis epidemic, with sustained increases in primary and secondary syphilis.10 This increase affects almost every demographic nationally. These new record levels are the highest numbers seen in more than 70 years resulting in a 2,140% increase in syphilis. 10 In a 2023 report by the CDC, over the past decade, there has been a 700% increase in cases of congenital syphilis in the United States4. Seventy six percent of untreated syphilis cases in pregnancy will result in an adverse outcome, including spontaneous abortions, miscarriages or stillbirths, neonatal death, low birth weight, or a child with stigmata of congenital syphilis. This alarming trend puts both mothers and infants at risk.6

What is Syphilis

Syphilis is a highly contagious sexually transmitted infection(STI) that can cause serious health problems without treatment. Infection develops in stages (primary, secondary, late and Latent, see below). Each stage can have different signs and symptoms. Syphilis is a disease caused by the bacterium Treponema pallidum subsp pallidum, (a spirochete bacteria), which can be fatal if left untreated and can facilitate the transmission and acquisition of HIV. Additionally, historical data demonstrates that untreated early syphilis in pregnant women, if acquired during the four years before delivery, can lead to infection of the fetus in up to 80% of cases and may result in stillbirth or death of the infant in up to 40% of cases.”7 Left untreated, the effects of syphilis can span decades.

Threat to Blood Supply

Every two seconds someone in the United States needs blood. It is essential for surgeries, cancer treatments, traumatic injuries, and chronic illnesses. The U.S. blood system is dependent on donations to meet the demand for those blood products. Less than 38 percent of the U.S. population is eligible to donate blood and out of those, less than 2% donate.8 Every drop of donated blood is valuable to those who receive a transfusion or other blood product. Because STDs are a threat to the nation’s blood supply, blood and cadaveric donations are tested for syphilis. 

Treponema pallidum subsp Pallidum, the causative agent of syphilis, induces the production of at least two types of antibodies in the human body. The Anti-treponemal antibody can be detected by the FTA-ABS (Fluorescent Treponemal Antibody Absorption) test, and the anti-nontreponemal antibody (reagin) is detected by using the Rapid Plasma Reagin (RPR) test.

Arlington Scientific advocates the use of the RPR test (a nontreponemal test) that detects antibodies formed in response to damaged host cells as the primary way of screening donors. The RPR test indicates if a person has an active infection. This test follows the CDC’s recommended traditional algorithm.9

In the reverse-sequencing algorithm, a person who has been diagnosed with syphilis will remain positive for life and therefore the reverse-sequencing algorithm is not useful in patients who have previously been diagnosed and treated for syphilis. Using the reverse algorithm for someone who has previously had a syphilis infection and was treated leads to increase costs because of the confirmatory testing requirement.

Primary Stage:

Syphilis is transmitted by individuals in either the primary or secondary stage of the disease but often these people do not even realize that they are infected. Primary syphilis is characterized by single or multiple ulcerative-like lesions known as chancres, a firm round, small and painless sore which appears at the site where the organism entered the body. Chancres can persist for 2-6 weeks before healing. Untreated, the disease will progress to the secondary stage.

Secondary Stage:

This stage of the disease begins 2-24 weeks after most primary lesions heal. It is characterized by a rash on one or several areas of the body. These rashes typically do not itch and can present while the initial chancre is healing or a few weeks after it has healed. The rashes typically appear on the palms of the hands and the bottom of the feet. These rashes range from difficult to see to rough, red, or reddish-brown spots. The rash can have a different appearance on different parts of the body and often even resembles rashes characteristic of other disease states. Other symptoms that can begin during the secondary stage are swollen lymph nodes, sore throat, fever, headache, weight loss, fatigue, and muscle aches. Signs and symptoms of secondary syphilis usually resolve in three months and can last up to twelve months.  Untreated, the infection will progress to the late and latent stage.

Late and Latent Stages

In this stage, the patient moves into the latent stage when the primary and secondary stages have passed. This final stage of the disease can last for years with little or no observable signs and symptoms as late as 10 – 20 years following the initial infection. In this stage, signs and symptoms may include dementia, paralysis, numbness, blindness, and difficulty coordinating movement. Internal organs including the brain, nerves, eyes, heart, blood vessels, liver, bones, and joints may be damaged. These complications can result in death.

Neurosyphilis, Ocular Syphilis and Otosyphilis

Without treatment, syphilis can spread to the brain and nervous system (neurosyphilis), the eye (ocular syphilis), or the ear(otosyphilis). This can happen during any of the stages described above.7


There are no home remedies or over-the-counter drugs that will cure syphilis. Syphilis, however, is easy to treat and cure in its early stages. A single injection of a long-acting penicillin is sufficient to cure a person who has primary, secondary or early latent syphilis. Individuals diagnosed with late latent syphilis or latent syphilis of unknow duration may receive additional doses of penicillin at weekly intervals. The treatment of syphilis will kill the bacterium and prevent further damage; however, it will not repair, or reverse damage already done. Patients allergic to penicillin can be treated with another antibiotic.9

Automated RPR Screening

The ASI® Automated RPR (rapid plasma reagin) Test for syphilis is a qualitative and semiquantitative nontreponemal flocculation test for the detection of reagin (anti-nontreponemal antibody) antibodies in human serum and plasma as a screening test for serological evidence of syphilis, for use on the ASI Evolution® Automated Syphilis Analyzer.

The ASI Evolution® is quickly becoming the standard for automated RPR screening. Now labs can simplify their workload with the ASI Evolution, FDA cleared for diagnostic, blood donor and cadaveric screening. Using the ASI Evolution makes more sense than ever,