Overview of syphilis and HIV

Various illnesses affect our lives on a daily basis. From mild colds to more severe forms such as cancers, our understanding of diseases is constantly changing. Thus, in this article, we will address two topics: syphilis and HIV.

What is syphilis? It is a sexually transmitted infection (STI) that is very much preventable and curable.¹ However, if left untreated it can be quite serious. It is caused by a bacteria known as Treponema pallidum which are thin, helical and tightly coiled.² It is transmitted via oral, vaginal or anal sex, during pregnancy and via blood transfusions.¹ It is particularly important in pregnant women as it can lead to stillbirth, death of newborns, and congenital syphilis (babies born with syphilis).¹

There are multiple stages of the development of syphilis, and they are summarised in table 1.

Table 1. Stages, timeline and manifestations of syphilis.³

Primary stage syphilis is classically described as a solitary non-tender genital chancre, which is the initial site of infection by Treponema pallidum.³ However, this can be easily missed by the person as it can be difficult to visualise; for example, in the cervix or anus/rectum.³ At times, chancres can be found in other areas such as the fingers, nipples and oral mucosa, although that accounts to about 2-7% of cases.³

If primary syphilis is left untreated, it can progress to the secondary stage, 6 to 8 weeks after the initial infection; the characteristic rash (pink to red macules and papules) in the secondary stage is seen on the face, trunk, and extremities.³ Syphilitic alopecia has been documented in this stage and is often described as a “moth-eaten” appearance although it occurs in only 4-12.5% of patients at this stage.³ In some patients, secondary syphilis can take a severe form known as ulceronodular or malignant syphilis and it has been seen in immunosuppressed patients.³

If left untreated in the secondary stage, syphilis can progress to the latent phase. In this stage, there is an absence of symptoms and it is divided into early and late latency and it is important to differentiate the two stages as this relates to the infectivity of the patient. Early latency stage is infectious infectious while the late latency is not.³

Once syphilis progresses to the tertiary phase, it is characterised as a persistent low level pathogen burden where the body’s response to this is a potent and self-destructive immune reaction.³

There are 3 manifestations of tertiary syphilis: neurosyphilis, cardiovascular syphilis and late benign syphilis:³

• Neurosyphilis: this form occurs due to the bacterial penetration of the blood-brain-barrier³ 
• Cardiovascular syphilis: this form takes place in the great vessels, most commonly presenting itself as ascending aortitis³
• Late benign syphilis: this form accounts to about one-half of cases and is manifested as granulomas, gummas, and psoriasiform³

On the other side, we will be talking about HIV. HIV stands for Human Immunodeficiency Virus which attacks the immune system; in particular our white blood cells, which leads to a weakened immunity.⁴ HIV is a retrovirus having 2 identical copies of single-stranded RNA molecules.⁵

Once HIV enters the body, it binds to glycoprotein CD4 that is present on various cells like T-lymphocytes, macrophages, dendritic cells and microglial cells of the central nervous system.⁵ Once the virus is bound to the cell, it releases its RNA inside and uses its mechanisms to revert its RNA to DNA and integrate itself into the immune cell’s genome.⁵ Infected and quiescent T-cells that have integrated provirus become important long-living reservoirs of HIV.⁵

Once these cells are activated, the HIV replicates and can then continue to infect other immune cells, which leads to the decreased number of T-cells, declined immunity, and death.⁶ Once the infection reaches an advanced stage, it leads to acquired immunodeficiency syndrome (AIDS), which has affected 36.7 million people as estimated in 2015.^4,6

HIV, like syphilis, can be transmitted sexually, through the use of shared needles, blood transfusion, or during childbirth or breastfeeding from an infected mother.⁷ It has two subtypes: HIV-1, which is the most common type and is responsible for AIDS globally, and HIV-2, which is less common and mostly found in western Africa.⁷

As our immune system weakens, we are more susceptible to infections of different kinds and that includes syphilis; coinfection with syphilis in HIV patients have become more and more common and they are at higher risk of developing neurosyphilis.³ Hence, it is important to address these cases and their treatment.

Epidemiology and coinfection

Syphilis has seen an increase in cases between 2018 and 2022; in 2018, syphilis (all stages) accounted for 113,739 cases and rose up to 203,500 cases by 2022 according to the CDC.⁸ Which sheds light on the need to investigate the cause of this increase and how to battle it.

Currently, HIV is a big global health concern as it has claimed around 40 million lives with continuous transmission globally, and even some countries have seen an increase in cases when it was previously on the decline.⁴ By the end of 2022, around 39 million people were estimated to be living with HIV, according to the World Health Organisation (WHO).⁴ It is a tricky infection to treat; currently there is no cure for HIV, however, using effective prevention, diagnosis and treatment/care can make it a manageable chronic condition.⁴

As mentioned previously, HIV can make people more susceptible to other infections; hence a coinfection with syphilis is more than probable.⁹ It was documented that the coinfection with syphilis and HIV can vary from 8 to 25%.¹⁰ The bidirectional interaction that occurs between HIV and syphilis is regarded as epidemiological synergy.

Studies have shown that syphilis can facilitate acquiring and transmitting HIV, which results in increased infectivity of HIV by impacting its shedding, replication, increasing the viral density, and disrupting the mucosa, as well as altering the immunity in the genital tract.¹¹

On the other hand, HIV can affect syphilis manifestations and blur the distinction between stages causing atypical symptoms; for example, the presence of numerous chancres in primary syphilis, or the persistence of chancres in secondary syphilis in HIV-positive individuals.⁹

Some people tend to be at more high risk than others and that includes: men (assigned at birth) who have sex with men (assigned at birth), female (assigned at birth) sex workers, college students and the elderly.¹¹

Symptoms

Symptoms of syphilis include:

• Ulcers on the penis, vagina, or anus. At times, ulcers can occur in the mouth, lips or hands
• White/grey warty growths in the genitals
• Rash that is not itchy
• White patches in the mouth
• Swollen glands
• Patchy hair loss
• Flu-like symptoms¹

Symptoms of HIV include:

• Short flu-like symptoms 2-6 weeks after infection that last for 1-2 weeks¹²
• After initial symptoms disappear, HIV can remain dormant with no symptoms present for years, all while the virus continues to inflict damage to the immune system.¹² This results in people not knowing if they are infected¹²

Diagnosis

Diagnosis of syphilis includes:

• Physical examination and sexual history
• Lab tests for the detection of Treponema pallidum like blood tests
• Rapid tests, self-test kits¹

Diagnosis of HIV includes:

• Self-test kits
• HIV confirmatory tests at the clinic or healthcare facility⁴

It is worth noting that in most cases, infected individuals can develop antibodies to HIV within 28 days of the infection.⁴ However, during this period, the antibody levels are low and may not be detected through the self-test kits or rapid tests but remain infectious to others.⁴ So, it is good to test for HIV again after 28 days.

Therapy

Syphilis is curable and is treated using antibiotics (penicillin) and this is the only recommended therapy for pregnant women by the WHO.¹ Second line treatments include doxycycline, ceftriaxone or azithromycin.¹

On the other hand, HIV currently has no cure, but it is treated with antiretroviral drugs to stop the virus from replicating in the body.⁴ Antiretroviral therapy (ART) does not eliminate and cure HIV, but it can increase the person’s immune system, and it must be taken daily for the rest of the patient’s life.⁴

However, HIV is preventable! And this can be done through multiple steps:

• Protected sex e.g. using condoms
• Getting tested for STIs
• Voluntary medical male circumcision
• Avoid using shared needles
• Medicines and medical devices to prevent HIV such as dapivirine vaginal rings, injectable long acting cabotegravir⁴

Summary

Syphilis and HIV are both sexually transmitted diseases that can lead to devastating results. While separate cases of the two are observed, coinfection with both of these illnesses can lead to a synergic effect; where syphilis can increase HIV infectivity and HIV can mask syphilis stages. Hence, it is important to take measures and have the appropriate treatments/preventions to lower the risk of acquiring these diseases, especially with cases going on the rise. Our health is very important and ignoring the signs can lead to detrimental results.