Yaws is a contagious disease caused by the bacteria Treponema pertenue, which is related to the bacteria that causes syphilis. It is usually found in tropical areas and spreads through direct skin contact.

Yaws is commonly found in 12 countries and over 300,000 cases were reported between 2008 and 2012.

What are signs and symptoms of Yaws?

The signs and symptoms of Yaws include: - Solitary nodules or multiple ulcerative non-tender papules that are usually yellow, with diameters ranging from 2 to 5 cm. - Primary lesions, also known as "Mother Yaw", heal spontaneously over 3 to 6 months, often leaving hyperpigmentation behind. - Primary lesions are most commonly found on the lower extremity. - Joint pains. - Secondary lesions appearing alongside primary ones. - Widespread papillomatous or ulcerative lesions. - Macular or hyperkeratotic palm and foot involvement. - Crab-like walk, often referred to as “crab-yaws”. - Generalized lymph node swelling. - General body discomfort. - Onset of specific bone disease. - Latent period between the secondary and tertiary stages, during which no clinical signs are evident but tests can still detect the yaws bacteria in the body. - Relapse of the disease during the latent period, typically manifesting around the armpits, anus, and mouth. - Tertiary phase, which is now rarely seen due to improved surveillance and antibiotic use. - Late lesions may occur 5 to 10 years after infection and are most commonly found near joints with ulcerative necrotic nodules. - Additional classical late findings include facial destruction, juxta-articular nodules (gummas), bowed shinbone (saber shins), nasal cartilage destruction (gangosa), or bony outgrowths of the maxilla near the nose (gondou).

Yaws is primarily spread through direct skin contact.

What else can Yaws be?

Syphilis, Bejel, Pinta, Leishmaniasis, Fusobacterium, pyoderma, and chancroid.

What kinds of test are needed for Yaws?

The types of tests needed for Yaws include: - Venereal Disease Research Laboratory (VDRL) test - Rapid Plasma Reagin (RPR) test - Treponema pallidum particle agglutination (TPPA) test - Haemagglutination (TPHA) test These tests are used to detect the presence of antibodies or proteins in the blood that are produced in response to the bacteria causing Yaws. The non-treponemal antibodies (VDRL and RPR) are used to diagnose and monitor treatment progress, while the treponema-specific antibodies (TPPA and TPHA) are used to confirm the diagnosis.

Yaws can be treated with medications such as penicillin aluminum monostearate, Benzathine penicillin, azithromycin, or lengthy courses of oral penicillin and tetracyclines. The primary alternative treatment is azithromycin, which has shown a cure rate of 96% after six months. The World Health Organization (WHO) has launched an initiative to eradicate yaws by giving a single dose of oral azithromycin to everyone in affected areas. However, there is concern about the development of resistance to azithromycin and other macrolide antibiotics.

What type of doctor should I see for Yaws?

A dermatologist or an infectious disease specialist.

Yaws - MD Searchlight

What is Yaws?

Yaws is a contagious disease that isn’t sexually transmitted, usually found in tropical areas, and is caused by the bacteria called Treponema pertenue. It’s related to a different type of bacteria, Treponema pallidum, which causes syphilis. Yaws is most often found in children living in the tropics and spreads through direct skin contact.

The disease starts with an initial, acute phase and then can develop into a chronic condition that comes and goes in some patients. Yaws progresses in stages, much like syphilis. Early on, it causes skin problems. Then, after a period where no symptoms are present, yaws can cause lumps known as gummatous nodules, scarring, and harmful changes to the bones in its later stages.

In the past, yaws was usually treated with a medicine called benzathine penicillin-G. However, a single dose of a different medicine, azithromycin, has been found to be just as effective for the initial and next stages of yaws. Therefore, azithromycin has become the primary treatment. The World Health Organization (WHO) aims to completely get rid of Yaws by the year 2020.

What Causes Yaws?

The Treponema genus is a group of bacteria that can’t be grown in a lab but includes some harmful species. These include T. pallidum, which causes syphilis; Treponema endemicum, which causes bejel; Treponema carateum, which causes pinta; and Treponema pertenue, which is responsible for yaws.

Back in 1998, scientists mapped the genome of T. pallidum for the first time. That led to genomic sequencing of twelve other treponemal pathogens, revealing that there’s not much variability between different sub-species. However, T. pertenue and its associated disease, yaws, stand out for their unique history and symptoms.

Unlike syphilis, yaws isn’t transmitted sexually or from a mother to her baby. It’s most common in children and spreads through skin-to-skin contact. In 1954, the World Health Organization (WHO) and the United Nations Children’s Fund made a concerted push to address yaws in areas where it’s common. Over the next two decades, the yearly occurrence of the disease dropped dramatically from 140.85 to just 1.25 per 100,000 people. As the disease continues to decline, it is hoped that with the right measures, yaws can be totally eradicated.

Risk Factors and Frequency for Yaws

Yaws is a disease that occurs largely in tropical areas with warm and humid climates. This disease primarily impacts children aged between 2 and 15, who also act as carriers for the bacteria responsible. Yaws spreads through direct skin contact, and while there have been suggestions that flies might transmit the disease, this theory hasn’t been proven. Despite primates carrying similar infections, there’s no evidence these are passed on to humans.

The bacteria that causes Yaws, Treponema pertenue, is found in Africa, Asia, and the South Pacific. Over 300,000 cases were reported to the World Health Organization between 2008 and 2012. The disease is endemic (commonly found) in 12 countries namely:

Benin
Cameroon
Central African Republic
Republic of the Congo
Cote d’Ivoire
Democratic Republic of the Congo
Ghana
Togo
Indonesia
Papua New Guinea
Solomon Islands
Vanuatu

Meanwhile, India and Ecuador have successfully eradicated the disease. Reports and studies indicate slight progress in managing the disease since 1992. However, it’s worth noting that up to 84% of all cases currently come from just three countries: Papua New Guinea, Solomon Islands, and Ghana.

Signs and Symptoms of Yaws

Yaws is a disease that progresses in three stages: primary, secondary, and tertiary. The primary stage is known for its solitary nodules or multiple ulcerative non-tender papules that are usually yellow, with diameters ranging from 2 to 5 cm. These papules typically manifest at the site of inoculation approximately 21 days after exposure, with the time to onset ranging from 9 to 90 days. Primary lesions, also known as “Mother Yaw”, heal spontaneously over 3 to 6 months, often leaving hyperpigmentation behind. Primary lesions are most commonly found on the lower extremity.

The disease progresses due to the spread of the yaws bacteria through the body’s lymphatic or blood system. This dissemination prompts a series of symptoms, including joint pains. The primary and secondary stages of yaws often overlap, with secondary lesions appearing alongside primary ones. Secondary symptoms typically develop one to two months after infection and can last up to two years. Symptoms include widespread papillomatous or ulcerative lesions and macular or hyperkeratotic palm and foot involvement, leading to a crab-like walk often referred to as “crab-yaws”. Additional symptoms during the secondary stage include generalized lymph node swelling and general body discomfort. The secondary stage also heralds the onset of specific bone disease.

Joint pains
Secondary lesions appearing alongside primary ones
Widespread papillomatous or ulcerative lesions
Macular or hyperkeratotic palm and foot involvement
Crab-like walk, often referred to as “crab-yaws”
Generalized lymph node swelling
General body discomfort
Onset of specific bone disease

In some patients, a latent period occurs between the secondary and tertiary stages. During this period, no clinical signs are evident, but tests can still detect the yaws bacteria in the body. This period occurs due to the body’s immune response against the bacteria, during which the disease can relapse and typically manifests around the armpits, anus, and mouth.

The tertiary phase historically affected about 10% of untreated patients. However, due to improved surveillance and the widespread use of antibiotics, it is now rarely seen. Late lesions may occur 5 to 10 years after infection and are most commonly found near joints with ulcerative necrotic nodules. Additional classical late findings include facial destruction, juxta-articular nodules (gummas), bowed shinbone (saber shins), nasal cartilage destruction (gangosa), or bony outgrowths of the maxilla near the nose (gondou).

Testing for Yaws

Diagnosis of certain conditions is made by considering a patient’s symptoms and conducting blood tests. These tests look for the presence of antibodies or proteins that your body produces in response to harmful substances. Two different types of antibodies are needed for a diagnosis, one reacting to a non-treponemal antigen and the other to a treponemal antigen.

The non-treponemal antibodies are the same type of antibodies used to diagnose syphilis, a sexually transmitted infection. These are identified through tests known as the Venereal Disease Research Laboratory (VDRL) and the Rapid Plasma Reagin (RPR). However, these tests are not always 100% accurate and can sometimes produce false-positive results, meaning the test might indicate you have the condition even when you do not. These tests are also useful to track the progress of a patient’s treatment, as falling levels of antibodies can suggest the disease is being successfully treated.

The other kind of antibodies that are looked for are treponema-specific antibodies. These can be identified through tests known as Treponema pallidum particle agglutination (TPPA) and haemagglutination (TPHA) assays. Once these tests become positive, they usually stay positive for life.

As it can be challenging to accurately diagnose a disease because the harmful organisms causing the disease are indistinguishable through testing and early symptoms may overlap with those of other diseases, several factors are considered. These include the patient’s geographical location and lifestyle, their clinical signs and symptoms, direct observation of the disease-causing organisms under a microscope, and data from blood tests. All these factors are necessary to accurately diagnose the condition.

Treatment Options for Yaws

In the 1950s, the treatment for yaws, an infection caused by the bacterium T. pertenue, began with a medication called penicillin aluminum monostearate. Over time, this medication was replaced with a different type of penicillin known as Benzathine penicillin. This switch was made because Benzathine penicillin stays active in the body for a longer period and is easier to administer. The amount of medication given was decided based on age, with smaller doses for younger children and larger doses for older children and adults. These doses were smaller than those used for treating venereal syphilis, a sexually transmitted infection caused by a similar type of bacteria.

Lengthy courses of oral penicillin and tetracyclines can also be effective in treating yaws; however, another medication called azithromycin, given in a specific dose, has become the primary alternative treatment. Studies have shown that Azithromycin is almost as effective as penicillin, with a cure rate of 96% after six months.

In 2012, the World Health Organization (WHO) launched an initiative to eradicate yaws. The plan involves giving a single dose of oral azithromycin to everyone living in areas where yaws is common. They also set up systems to find and treat new cases of the disease. The goal of this initiative is to completely erase yaws by the year 2020.

However, there is a concern regarding the development of resistance to macrolides, the family of antibiotics to which azithromycin belongs. T. pallidum, a bacteria closely related to T. pertenue and responsible for syphilis, is notably resistant to this type of antibiotics, which raises concerns about potential resistance in yaws as well.

Yaws is a medical condition that can be easily confused with other diseases because its early signs, such as damage to the bones, are similar. The skin symptoms of other illnesses can look a lot like those of yaws. Some of these diseases are:

Syphilis (T. pallidum): This disease differs from yaws as it occurs all over the world, mainly in adults who’ve had sexual contact, and starts with sores primarily on genitals. It can be passed from a pregnant woman to a baby, and may result in serious complications in the nervous system and heart later on.
Bejel (T. endemicum): While this also affects children, it differs from yaws in a lot of ways. It’s found in hot, dry areas including African deserts and Saudi Arabia and is spread through saliva. The initial skin symptoms are rare and usually occur in the mouth, and they don’t spread much. The nose and palate can be damaged late in the disease.
Pinta (T. carateum): This disease starts with skin sores on the lower body and is spread through skin contact. It’s common in hot and humid climates in South and Central America. Unlike yaws, this is a disease of adults and only the skin is affected. A common late symptom is a decrease of sodium in the skin.

Ulcers that appear in tropical regions from diseases like Leishmaniasis, Fusobacterium, or pyoderma can look similar in the early stages that begin with a small, red bump which then becomes an ulcer. One example is an infection called chancroid caused by Haemophilus ducreyi, which leads to painful skin sores due to sexual contact. These may appear on the genitals and elsewhere in areas where the disease is common. These sores also respond well to the antibiotic azithromycin.

What to expect with Yaws

The outlook for patients is generally very positive if the condition is caught during the primary or secondary stages. With proper treatment, the most severe or ‘tertiary’ stage of the disease rarely occurs. Primary and secondary symptoms usually clear up on their own over a period of 3 to 6 months, with or without treatment. However, without treatment, some patients may progress to the late-stage disease.

If the disease does reach this tertiary stage, it can lead to serious health problems. This can include destruction of bone tissue, which can cause significant facial disfigurement and bending of the shin bones, making walking difficult.