What is Yaws?

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Quick Answer: What is yaws?

Yaws is a long-lasting, potentially disfiguring skin disease caused by the bacterium Treponema pallidum subspecies pertenue. It spreads through skin contact with an infected person's sores and mostly affects children under 15. It starts as a skin growth that ulcerates, then causes more lesions and bone pain. Antibiotics cure it but cannot undo late-stage damage. [1]

What the research says

• One oral dose of azithromycin works as well as an injection. In a randomised trial of 250 children in Papua New Guinea, 96% (106 of 110) treated with azithromycin were cured at 6 months versus 93% (105 of 113) with benzathine benzylpenicillin (difference −3.4%, 95% CI −9.3 to 2.4), meeting the non-inferiority criteria, with similar mild adverse events (8% vs 7%) (Mitjà et al., The Lancet, 2012). [3]

• Repeated mass treatment lowers yaws more than a single round. In a cluster-randomised trial across 38 wards in Papua New Guinea, active yaws fell from 0.43% to 0.04% with three rounds of mass azithromycin, compared with 0.46% to 0.16% after one round plus targeted treatment (relative risk 4.08, 95% CI 1.90–8.76). Three macrolide-resistant cases were found in the three-round group (John et al., New England Journal of Medicine, 2022). [4]

• One round is not always enough to stop transmission. On Lihir Island (population 16,092), mass azithromycin at 84% coverage plus targeted treatment cut active yaws from 1.8% to a low of 0.1% at 18 months, but it rose again to 0.4% by 42 months, and five cases from one village carried azithromycin-resistance mutations (Mitjà et al., The Lancet, 2018). [5]

Key Takeaways

What is yaws, and how does it spread?

Yaws belongs to a group of chronic bacterial infections called the endemic treponematoses, which also includes bejel and pinta. It is also known as pian, framboesia or bouba. Humans are currently believed to be the only reservoir, and the infection passes from person to person through minor skin injuries. [2] [1]

Yaws is found mostly in poor, rural communities with limited access to clean water, sanitation and health care. About 75–80% of people affected are children under 15, with peak incidence at ages 6–10, and boys and girls are equally affected. In 2021, 123,866 suspected cases were reported to WHO from 13 countries, most of them in the Western Pacific Region, although only a small fraction were laboratory-confirmed.

What are the four stages of yaws?

Yaws is a progressive disease. Without treatment it moves through four possible stages over several years.

1. Primary Yaws

The first sign is a skin growth often called the “mother yaw,” usually on the legs or feet, which appears after an incubation period of 9 to 90 days (about 21 days on average). It starts small and grows into a large, itchy ulcer that may be pus-filled and crusts over. This stage can last three to six months, and the lesion may heal on its own and leave a scar. The lesion is teeming with bacteria and is highly infectious. [1] [2]

2. Secondary Yaws

Secondary yaws usually starts a month or two after the first lesion, but it can begin up to two years later. Multiple skin growths appear, often on the hands, arms, legs or feet. They may be wart-like, ulcer-like, raised and “raspberry-like,” red or yellow, scaly or thick. The infection can spread to the bones, causing pain and swelling of the fingers, toes, arms or legs (dactylitis). Swollen lymph nodes, tiredness and malaise can also occur. [1]

3. Latent Yaws

In latent yaws there are no symptoms, but blood tests remain positive for the bacteria. This stage can last for years, and it is possible that the person is still contagious during this period. [1]

4. Tertiary (Late) Yaws

Without treatment, about 10% of people develop late yaws five to ten years after their first symptoms. This stage is destructive but not contagious. It can cause: [1]

• Large growths near the joints. [1]

• Deep open sores that extend into skin, cartilage and bone. [1]

• Gangosa: destruction of bone and cartilage in the nose and face. [1]

• Hard, thick patches (plaques) on the hands and feet that can make walking difficult. [1]

What complications can yaws cause?

Untreated yaws can cause swollen fingers and toes, bone infection, tissue death, permanent disfigurement and physical disability. [1]

• Swollen fingers and toes (dactylitis). [1]

• Infection of the bones or their lining (periostitis). [1]

• Tissue death (necrosis) and additional bacterial infections. [1]

• Permanent disfigurement and scarring. [1]

• Physical disability and difficulty walking. [1]

How is yaws different from syphilis?

Yaws is caused by bacteria that are almost identical to those that cause syphilis, but the two diseases behave differently. [1]

How is yaws diagnosed?

Yaws is diagnosed by examining the skin and asking about health history and travel, with blood tests and PCR on lesion samples used to confirm it. Early lesions are often easy to recognise clinically, but ulcers can be harder to diagnose. Common tests include:

• Serological (blood) tests: detect treponemal infection, but cannot distinguish yaws from syphilis, so results need careful clinical interpretation in adults from endemic areas. [2]

• PCR on lesion samples: detects the bacterial DNA and definitively confirms yaws. It can also check for azithromycin resistance. [2]

• Ruling out look-alikes: other infections can cause similar ulcers. WHO notes that about 40% of ulcers clinically misidentified as yaws are caused by an unrelated bacterium, Haemophilus ducreyi. [2]

How is yaws treated?

Yaws is highly responsive to antibiotics, and a single dose is usually enough. Treatment works at any stage, but earlier treatment lowers the risk of serious complications. Antibiotics cannot reverse bone or tissue damage that has already happened. [1]

Patients should be re-examined 4 weeks after treatment. Complete clinical healing occurs in over 95% of cases, and anyone with presumed treatment failure needs testing for macrolide resistance. Close contacts of people with yaws should also be treated. [2]

How can yaws be prevented, and what are the global eradication efforts?

Yaws has no vaccine, so prevention relies on avoiding contact with lesions, good hygiene and treating cases and contacts, alongside mass azithromycin treatment. Prevention rests on avoiding skin contact with lesions, health education and better personal hygiene, and on treating cases and their contacts.

WHO has targeted yaws for eradication using total community treatment (mass treatment), in which oral azithromycin is given to an entire population in areas known to have yaws, with at least 90% coverage. Trial results suggest that repeated rounds work better than a single round, and that surveillance must continue because yaws can re-emerge and, rarely, azithromycin-resistant strains can appear. [2]

A systematic review of surveillance data found that 256,343 yaws cases were reported to WHO from 13 endemic countries between 2010 and 2013, and that 84% came from Papua New Guinea, the Solomon Islands and Ghana (Mitjà et al., The Lancet Global Health, 2015). [6]

Conclusion

Yaws is a disease of poverty and limited access to health care, yet it is one of the few diseases that can realistically be eliminated. A single dose of a cheap antibiotic cures the infection and breaks the cycle of transmission. Awareness, early diagnosis and community-wide treatment, backed by careful surveillance, are the keys to protecting children from lifelong scars and disability.

Frequently Asked Questions

What is yaws?

A chronic bacterial infection that mainly affects the skin, bones and cartilage.

What causes yaws?

The bacterium Treponema pallidum subspecies pertenue.

Is yaws a sexually transmitted disease?

No. It spreads through non-sexual, skin-to-skin contact with the lesions of an infected person.

Who is most affected by yaws?

Children under 15 who live in warm, humid, rural tropical regions. WHO reports that 75–80% of people affected are children, with peak incidence at ages 6–10.

Where is yaws most common?

Parts of the Pacific Islands, West and Central Africa and South-East Asia. WHO lists 15 countries as currently known to be endemic.

What is the "mother yaw"?

The first skin lesion to appear after infection. It starts as a small growth and becomes a larger, itchy, crusted ulcer.

How does yaws spread?

Through direct contact with the ulcers or skin growths of someone with early yaws, usually through minor cuts or broken skin.

Can yaws be cured?

Yes. A single dose of an antibiotic, usually oral azithromycin, cures the infection in the large majority of cases.

What happens if yaws is not treated?

It can progress to chronic skin ulcers and permanent damage to bone, cartilage and soft tissue, including disfigurement and disability.

Is yaws related to syphilis?

Yes. The bacteria are very closely related, but yaws is not sexually transmitted.

Can yaws lead to blindness?

Yaws mainly affects the skin, bones and cartilage rather than the eyes.

What are raspberry-like growths?

The bumpy, red or yellow skin lesions that appear in secondary yaws.

What is gangosa?

A late complication in which bone and cartilage of the nose and face are destroyed.

How long is the incubation period?

Between 9 and 90 days, with an average of about 21 days, according to WHO.

Can adults get yaws?

Yes, although it is much more common in children. Experts think adults in endemic areas may build up some immunity over time, while visitors from non-endemic areas would have none.

Is there a vaccine for yaws?

No. There is currently no vaccine.

What antibiotic treats yaws?

Azithromycin (a single oral dose of 30 mg/kg, up to 2 g) is the WHO-preferred treatment. Benzathine penicillin is an injectable alternative for treatment failure or when azithromycin cannot be used.

Can yaws come back after treatment?

Re-infection is possible if you are exposed again. Untreated yaws can also relapse months or years later.

How is yaws diagnosed?

By examining the skin lesions and reviewing your health history, often with blood tests. Lab tests on lesion samples, including PCR, can confirm the infection.

Is yaws painful?

Early lesions are itchy and can be uncomfortable. Bone involvement in secondary yaws can cause significant pain and swelling.

Can yaws affect the heart or brain?

Yaws mainly affects the skin, bones and cartilage. Unlike syphilis, it is not typically described as affecting the heart or brain.

What is latent yaws?

A stage in which the person has no symptoms but still tests positive for the bacteria. It can last for years.

Is yaws contagious during the latent stage?

It is possible, according to Cleveland Clinic, so treatment is still needed.

Does yaws leave scars?

Yes. Healed ulcers often leave visible scars.

What is dactylitis?

Swelling of the fingers or toes, which can occur in secondary yaws.

Can yaws be spread by insects?

There is no evidence that insects spread yaws in humans.

Is yaws found in the United States?

It is not endemic there. Yaws occurs in warm, humid tropical regions, and travellers to those areas can be exposed.

How does WHO plan to eradicate yaws?

Through total community treatment: giving oral azithromycin to an entire population in endemic areas with at least 90% coverage, followed by surveillance and treatment of cases.

What is periostitis?

Inflammation of the lining of the bone, a complication of yaws.

Why is yaws called framboesia?

Because the secondary lesions look like raspberries (framboise in French). Other names include pian and bouba.

Can yaws affect the palms and soles?

Yes. Hard, thick patches on the hands and feet can develop in late yaws and make walking difficult.

Is yaws fatal?

Yaws itself is not usually fatal, but it can cause lasting disfigurement and disability if untreated.

Can you get yaws from swimming?

No. Transmission requires direct contact with an infected person's skin lesions.

Can yaws affect the nose and face?

Yes. In late yaws, destruction of bone and cartilage in the nose and face (gangosa) can occur.

What is the difference between primary and secondary yaws?

Primary yaws is the first single lesion. Secondary yaws involves multiple skin lesions and can include bone pain and swelling.

How long does the secondary stage last?

Secondary symptoms usually begin a month or two after the first lesion, and sometimes up to two years later. Some skin lesions can heal on their own.

Is tertiary yaws contagious?

No. Contact with late-stage skin growths does not spread yaws.

Can yaws be mistaken for other diseases?

Yes. Other infections such as syphilis, leishmaniasis, leprosy and Buruli ulcer can look similar, and WHO notes that about 40% of ulcers clinically misidentified as yaws are caused by Haemophilus ducreyi.

What does the mother yaw look like?

A crusted, often yellowish-red ulcer that may be pus-filled and is most often on the legs or feet.

Are yaws blood tests the same as syphilis tests?

Yes. Standard treponemal and non-treponemal blood tests cannot tell yaws and syphilis apart.

Can hygiene prevent yaws?

Health education and better personal hygiene help reduce spread, but avoiding contact with lesions and treating cases and contacts are the key measures.

Does yaws thrive in dry climates?

No. It occurs mainly in warm, humid, tropical forest areas.

Is yaws a neglected tropical disease?

Yes. WHO classifies it as a neglected tropical disease.

Can pets get yaws?

No. Humans are currently believed to be the only reservoir, and transmission is from person to person.

Does yaws affect growth and mobility?

Bone and joint damage and thick plaques on the feet can cause lasting disability, which is why early treatment matters.

How many people are affected by yaws?

In 2021, 123,866 suspected cases were reported to WHO from 13 countries, and 1,102 cases were confirmed from 9 countries.

How long until I know the treatment worked?

WHO advises re-examining patients 4 weeks after treatment. Complete clinical healing is seen in over 95% of cases.

Is one dose really enough?

For most patients, yes. Anyone with presumed treatment failure needs further testing, including for macrolide resistance, and may be given benzathine penicillin.

What is the economic impact of yaws?

Chronic ulcers and disability can limit school attendance and the ability to work, and the disease is closely tied to poverty and poor access to health care.

How long has yaws been a problem?

Yaws has long been known in tropical regions. In the 1950s, more than 90 countries and territories were endemic, and mass campaigns since then have greatly reduced cases.

References

1. Cleveland Clinic. Yaws: Causes, Symptoms, Diagnosis & Treatment. Cleveland Clinic Health Library. Last updated May 24, 2023. https://my.clevelandclinic.org/health/diseases/25011-yaws

2. World Health Organization. Yaws. WHO Fact Sheets. 12 January 2023. https://www.who.int/news-room/fact-sheets/detail/yaws

3. Mitjà O, Hays R, Ipai A, et al. Single-dose azithromycin versus benzathine benzylpenicillin for treatment of yaws in children in Papua New Guinea: an open-label, non-inferiority, randomised trial. The Lancet. 2012;379(9813):342–347. PMID: 22240407. https://doi.org/10.1016/S0140-6736(11)61624-3

4. John LN, Beiras CG, Houinei W, et al. Trial of three rounds of mass azithromycin administration for yaws eradication. New England Journal of Medicine. 2022;386(1):47–56. PMID: 34986286. https://doi.org/10.1056/NEJMoa2109449

5. Mitjà O, Godornes C, Houinei W, et al. Re-emergence of yaws after single mass azithromycin treatment followed by targeted treatment: a longitudinal study. The Lancet. 2018;391(10130):1599–1607. PMID: 29428183. https://doi.org/10.1016/S0140-6736(18)30204-6

6. Mitjà O, Marks M, Konan DJP, et al. Global epidemiology of yaws: a systematic review. The Lancet Global Health. 2015;3(6):e324–e331. PMID: 26001576. https://doi.org/10.1016/S2214-109X(15)00011-X

Disclaimer

The information provided in this article is for educational purposes only and is not intended as medical advice. Always seek the advice of a qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this article.