late yaws

Late Yaws: A Chronic Tropical Infection

Late yaws, also known as tertiary yaws, is a non-contagious stage of the tropical infection caused by Treponema pallidum pertenue. This stage occurs 5-10 years after the initial symptoms and can cause significant damage to the skin, bones, and joints.

Characteristics of Late Yaws

• Destructive and deforming lesions: Late yaws is characterized by destructive and deforming lesions of the skin, bones, and joints.
• Non-contagious: Unlike early stages of yaws, late yaws is not contagious.
• Possible complications: If left untreated, late yaws can lead to possible complications such as nose and bone disfiguration, palmar/plantar hyperkeratosis (thickening of skin on palms and soles), and joint damage.

Symptoms

• Skin lesions: Late yaws can cause skin lesions that are often destructive and deforming.
• Bone and joint damage: The infection can also affect the bones and joints, leading to pain and deformity.
• Disfiguration: In severe cases, late yaws can cause significant disfiguration of the face and body.

References

• [2] Late yaws is characterized by destructive and deforming lesions of the skin, bones, and joints.
• [9] Late yaws, occurring five years after initial infection, is characterized by nose and bone disfiguration as well as palmar/plantar hyperkeratosis (thickening of ...).

Late Stage Yaws: Signs and Symptoms

Yaws, caused by the bacterium Treponema pertenue, can progress to a late stage if left untreated or inadequately treated. At this stage, the disease may have already caused significant damage to the skin and bones.

• Skin symptoms: Late yaws lesions are typically near joints and can be ulcerative necrotic nodules [1].
• Bone damage: The disease can cause bowed shinbones (periostitis), leading to limping and impaired mobility [4].
• Other symptoms: Thickening of the palms and soles (hyperkeratosis) may also occur, in addition to fever, sore throat, enlargement of lymph nodes, and headaches [7].

It's essential to note that late-stage yaws can be challenging to treat, and some damage caused by the disease may not be fully reversible, even with treatment [2].

Late Yaws Diagnostic Tests

Late yaws, also known as Bejel or Pinta, is a chronic and non-contagious form of syphilis that can occur years after the initial infection. Diagnosing late yaws can be challenging due to its asymptomatic nature. However, several diagnostic tests can help confirm the presence of the disease.

• Serological Tests: While there is no specific blood test for yaws, serological tests for syphilis are often positive in people with yaws [6]. Non-treponemal serological tests, such as the Rapid Plasma Reagin (RPR) test, can become positive during the initial stage of yaws infection [7].
• Darkfield Microscopy: This diagnostic method involves examining a sample from a skin lesion or other affected area under a microscope to detect the presence of Treponema pallidum, the bacteria that cause syphilis and yaws. However, this test is not commonly used for late yaws diagnosis.
• PCR (Polymerase Chain Reaction): Molecular diagnostics, such as PCR, can be used to detect the genetic material of T. pallidum in a sample from an affected area [3]. This method is more accurate and sensitive than traditional serological tests but may not be widely available.

Key Points

• Serological tests for syphilis are often positive in people with yaws.
• Darkfield microscopy can detect the presence of Treponema pallidum, but it's not commonly used for late yaws diagnosis.
• Molecular diagnostics like PCR can accurately detect T. pallidum genetic material.

References

[3] Zhang Y. (2022). Diagnostic methods for active syphilis and yaws include direct detection of treponemes or treponemal DNA sequences (ie, darkfield microscopy, direct fluorescent antibody test, and polymerase chain reaction) [Cited by 8]. [6] Dec 31, 2023 — There is no blood test for yaws. However, the blood test for syphilis is often positive in people with yaws because the bacteria that cause yaws are closely related to those that cause syphilis. [7] Stamm LV. (2014). During the initial stage of yaws infection, non-treponemal serological tests for syphilis—such as the rapid plasma reagin (RPR) test—become positive [Cited by 1].

Treatment Options for Late Yaws

Late yaws, also known as tertiary yaws, can be a serious condition if left untreated. Fortunately, there are effective treatment options available.

• Azithromycin: This oral antibiotic has been shown to be highly effective in treating late yaws. A single dose of azithromycin can clear the infection from the person's system [7][9].
• Benzathine Penicillin G: This injectable penicillin is generally curative in any stage of endemic treponematoses, including late yaws. Treatment typically involves a single injection of 2.4 million units [8].

It's essential to note that while these treatments are effective, they may not be available or accessible in all areas where late yaws is prevalent.

Prevention and Control

To prevent the spread of late yaws, mass treatment campaigns using oral azithromycin have been implemented in some regions. These campaigns aim to target both symptomatic and latent cases, particularly in children [14].

However, as highlighted by a recent study, sustained implementation of mass treatment with oral azithromycin followed by active surveillance and targeted treatment is crucial for effective control and eventual eradication of the disease [12].

Differential Diagnosis of Late Yaws

Late yaws, also known as tertiary syphilis, can be challenging to diagnose due to its similarity with other tropical diseases. The differential diagnosis of late yaws includes:

• Tropical ulcers: These are a common cause of skin lesions in tropical regions and can resemble the gummas seen in late yaws.
• Haemophilus ducreyi infections: This bacterium causes chancroid, which can present with painful ulcers that may be confused with late-stage yaws.
• Syphilis: As a key differential diagnosis for all three endemic treponematoses (yaws, bejel, and pinta), syphilis can present with similar skin lesions to late yaws.
• Leishmaniasis: This parasitic infection can cause skin ulcers that may resemble the gummas seen in late yaws.
• Leprosy: Leprosy, also known as Hansen's disease, can cause skin lesions and nerve damage that may be confused with late-stage yaws.
• Buruli ulcer: This bacterial infection can cause large skin ulcers that may resemble the gummas seen in late yaws.

According to [4], the differential diagnosis of yaws is extensive, and the clinical diagnosis may be difficult even for experienced clinicians. The presence of pathological manifestations was identified in 49.10% (191/389) of individuals evaluated, with 6.28% (12/191) having lesions compatible with consistent differential diagnoses ([13]).

It's essential to note that late yaws can also present with visceral, neurologic, and neuro-ophthalmologic complications, which may require a more comprehensive diagnostic approach ([10]). A discussion with a physician with expertise in tropical medicine is recommended to ensure the best outcome for patients suspected of having late-stage yaws.