Edit concept Question Editor Create issue ticket



Yaws is a chronic bacterial infection caused by Treponema pallidum subspecies pertenue. This disease affects the skin, bones, and cartilage and is endemic in tropical regions of Asia, Africa, Latin America, and the western Pacific.


Yaws is mainly found in children who reside in endemic regions. Inoculation occurs when individuals are exposed to infected individuals [6] [7].

The following are the clinical stages:


The mother yaw, or primary lesion, forms at the contact site. This is usually a minor trauma on the skin, such as a cut, scratch, or bite on the lower extremities or buttocks. Specifically, the lesion appears as a non-tender, pruritic, reddish papule that grows in size and transforms into a papilloma. It contains central hypopigmentation and the healing process takes 3 to 6 months and is followed by the development of scars.

If bones are joints are affected, pain and swelling may ensue. Furthermore, associated symptoms at this stage are fever and lymphadenopathy.


This phase lasts between 6 to 16 weeks.


Disseminated lesions of the skin and bones may form after a latency phase. The daughter yaws are commonly positioned close to the mouth and nose. They grow, ulcerate and produce an exudative fluid containing the organisms. Also, papules, macules and nodules may arise. Overall, secondary lesions may persist for weeks to months and may resolve without treatment. Scarring does not usually occur. This phase may also feature constitutional symptoms.

Complications include thickening of the skin, which manifests as painful hyperkeratotic plaques that form fissures. Consequently, these painful and uncomfortable skin manifestations make it difficult to walk and hence the patient develops a crablike gait referred to as crab yaws.

Bone sequelae include osteoperiostitis and fusiform swelling of the metatarsal and metacarpal joints.


This late stage occurs in 10% of infected patients. It presents with damage to the skin and bones after 5 to 15 years of latency. The nervous system and the eyes may also be affected. Furthermore, this phase is characterized by the formation of well-demarcated subcutaneous nodules, which go on to develop abscesses, necrosis and ulcerations.

Infection of the ulcers is typically followed by further destruction of the skin. If the ulcers coalesce, this results in the production of serpiginous channels that eventually heal with keloid formation. Consequently, these patients suffer from severe deformities and contractures.

Finally, bone complications such as osteomyelitis, hypertrophic periostitis, and others occur.

  • After weeks to years, joints and bones may become painful, fatigue may develop, and new skin lesions may appear. The skin of the palms of the hands and the soles of the feet may become thick and break open.[en.wikipedia.org]
  • Chronic medical conditions include diabetes, epilepsy, and chronic fatigue syndrome. Disease Illness or sickness often characterized by typical patient problems (symptoms) and physical findings (signs).[healthdictionary.info]
  • […] round, hard swelling of the skin, 2 to 5 centimeters in diameter. [3] The center may break open and form an ulcer. [3] This initial skin lesion typically heals after three to six months. [4] After weeks to years, joints and bones may become painful, fatigue[en.wikipedia.org]
  • Their bodies were tightly bandaged to enable them to endure the excessive fatigue of their great ride through Central Asia.[britannica.com]
  • […] fascitises fashioners fashioning fashionist fastballer fastenings fastidious fastigiate fastigiums fastnesses fatalistic fatalities fatbrained fatherhood fatherings fatherland fatherless fatherlike fathership fathomable fathometer fathomless fatigating fatiguable[findmeaword.net]
Generalized Lymphadenopathy
  • Primary stage Early yaws lesions include the following: Papilloma Serpiginous papilloma Ulceropapillomata Squamous macules Maculopapules Nodules Plaques Hyperkeratosis of palms and soles Bone and joint lesions Generalized lymphadenopathy (may occur) The[emedicine.medscape.com]
  • Split papules at the labial commissures (angular stomatitis, as in yaws patients) ( Fig. 3C ), nonitchy skin eruptions, generalized lymphadenopathy, and laryngitis are common manifestations ( 54 ).[dx.doi.org]
Saber Shin
  • Saber shin due to chronic untreated osteoperiostitis.[slideplayer.com]
  • Chronic osteitis of the tibia can lead to saber shins. In about 1% of patients, there is occurrence of bilateral hypertrophic osteitis of the external aspects of the nasal processes of the maxillae with persistent swelling.[emedicine.medscape.com]
  • For example, some patients develop destructive ulcerations of the nasopharynx, palate and nose (termed gangosa), painful skeletal deformities, especially in the legs (termed saber shins), and other soft-tissue changes (gummas, inflammatory cell infiltration[medicinenet.com]
  • The symptoms of yaws are different from syphilis and include: the appearance of papillomatous lesions, arthralgia, malaise, bone and cardiovascular degradation. Of particular note, yaws is easily treatable using a single dosage of antibiotic.[jpoles1.github.io]
  • […] antibiotics, hematogenous and lymphatic dissemination of the bacteria may occur and lead to the development of secondary yaws, a condition characterized by contagious, superficial patchy scaling of the skin and plaques of the palms and soles accompanied by arthralgia[nejm.org]
  • Arthralgias are well-recognized symptoms of secondary-stage yaws and usually affect the knees, ankles, elbows, and wrists. They do not in themselves constitute an indication for a radiological study.[cid.oxfordjournals.org]
  • Site Ano-genital Site Legs, ankles Secondary Incubation Weeks-24 months Incubation Weeks-24 months Clinical presentation Skin rash Lymphadenopathy Mucosal lesions Clinical presentation Arthralgia Malaise Skin lesions Polyosteitis of fingers, feet or long[ncbi.nlm.nih.gov]
  • At this stage, regional lymphadenopathy and arthralgia may also occur ( 25 , 29 ).[dx.doi.org]
Joint Deformity
  • By involving skin, bone, and joints, yaws can produce deep ulcerations, joint deformities, and bone destruction.[ncbi.nlm.nih.gov]
  • The patient had bone and joint deformities and hyperkeratotic lesions of the palm and sole. The differential diagnosis of the nonvenereal treponematosis is discussed in the light of the clinical and laboratory findings and the patient's history.[ncbi.nlm.nih.gov]
  • In its primary stage, yaws infection causes skin lesions and if untreated progresses into severe bone and joint deformations of the extremities and face. Infection is transmitted from person-to-person by direct contact with contagious lesions.[sciencedaily.com]
  • Tertiary yaws is characterized by destructive cutaneous lesions and bone and joint deformities ( 1 , 4 ).[jcm.asm.org]
Skin Ulcer
  • METHODS: We performed repeated clinical surveys for active yaws, serologic surveys for latent yaws, and molecular analyses to determine the cause of skin ulcers and identify macrolide-resistant mutations before and 6 and 12 months after mass treatment[ncbi.nlm.nih.gov]
  • Ulcers caused by Haemophilus ducreyi is an important cause of skin ulcers (2) (mostly on the legs) which clinically mimic the ulcerative form of yaws complicates clinical diagnosis.[who.int]
  • Haemophilus ducreyi as a cause of skin ulcers in children from a yaws-endemic area of Papua New Guinea: a prospective cohort study. Lancet Glob Health 2014 ;2: e235 - e241 17. Centurion-Lara A, Castro C, Shaffer JM, et al.[nejm.org]
  • In both parks skin ulcerations caused by Treponema are common in wild baboons. In about 20 per cent of the wild-caught flies Treponema-DNA was found.[sciencedaily.com]
  • This features deep skin ulcers with much tissue destruction, bone changes and leprosy-like deformity. Yaws is easily treated with antibiotics such as penicillin or tetracycline.[medical-dictionary.thefreedictionary.com]
Tropical Ulcer
  • Overcrowding, poor hygiene and poor socioeconomic conditions favours the spread of the yaws References : Yaws simulates the lesions of scabies, impetigo, skin tuberculosis, tinea versicolor, tropical ulcer, leprosy and psoriasis.[nhp.gov.in]
  • Yaws simulates the lesions of scabies, impetigo, skin tuberculosis, tinea versicolor, tropical ulcer, leprosy and psoriasis. It may also accompany these diseases.[web.archive.org]
  • In this region, a diagnosis of yaws can be differentiated from primary lesions of tropical ulcers [ 22, 23 ], hence, usefulness of serological tests to overcome this difficulty with diagnosis.[bmcresnotes.biomedcentral.com]
  • ulcer in Africa, Nature, 1950 , vol. 165 (pg. 398 - 9 ) 18 Aureomycin in the treatment of yaws, Am J Trop Med Hyg, 1951 , vol. 31 (pg. 20 - 3 ) 19 The modern treatment of frambesia (yaws), West Indian Med J, 1951 , vol. 1 (pg. 81 - 92 ) 20 Oral propionyl[cid.oxfordjournals.org]
Initial Lesions of Yaws
  • The initial lesion of yaws is teemed with the bacteria. The incubation period is 9–90 days, with an average of 21 days. Without treatment, infection can lead to chronic disfigurement and disability.[who.int]
  • The initial lesion of yaws is teemed with the bacteria. Contact with this fluid, especially among children who play together and sustain minor injuries, leads to transmission of infection. The incubation period is 9–90 days (average 21 days).[web.archive.org]
  • Disease History, Characteristics, and Transmission The initial lesion of yaws appears where the bacteria enter the skin, and soon a red bump called a papule develops. The papule, measuring 0.8–2 in (2–5 cm) in diameter, is painless but often itchy.[encyclopedia.com]
Plantar Hyperkeratosis
  • Late yaws appears after five years of the initial infection and is characterized by disabling consequences of the nose, bones and palmar/plantar hyperkeratosis.[allcountries.org]
  • Symptoms of Yaws A painless ulcer that has a scab Papillomas A thickening palmar/plantar hyperkeratosis Treatment The treatment for Yaws is not expensive and is a single dose of an antibiotic called: Benzathine Penicillin.[reliawire.com]
  • Late yaws appears after five years of the initial infection and is characterized by disfigurement of the nose and bones, and palmar/plantar hyperkeratosis (thickening of the palms of the hand and the soles of the feet).[web.archive.org]
  • The operational definition of a case of yaws is "any person who lives in an endemic area and presents with one or more of the following signs: painless ulcer with scab, papilloma, palmar/plantar hyperkeratosis (thickening)" [ 2 ].[bmcresnotes.biomedcentral.com]
  • People with eczema often get skin infections because the breaks in their skin let germs in. If an eczema treatment doesn’t work, or if the rash gets worse, it could be an infection.[webmd.com]
  • Contenuti: Skin: basic structure and function -- Cutaneous signs and diagnosis -- Dermatoses resulting from physical factors -- Pruritus and neurocutaneous dermatoses -- Atopic dermatitis, eczema, and noninfectious immunodeficiency disorders -- Erythema[worldcat.org]
  • In addition, yaws might be confused with other skin conditions, such as eczema, psoriasis, idiopathic keratoderma calluses, infected bites, excoriated chronic scabies, tungiasis, sarcoidosis, verrucae, and vitamin deficiencies ( 4 ).[jcm.asm.org]
  • Furthermore, diagnosis could be difficult in the presence of the dermatophytosis tinea corporis, pellagra, eczema, psoriasis, and leprosy ( 25 , 225 , 226 ).[dx.doi.org]
Facial Ulceration
  • Gangosa or rhinopharyngitis mutilans denotes mutilating facial ulceration of the palate and nasopharynx secondary to osteitis.[ncbi.nlm.nih.gov]
  • Author information 1 Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland.[ncbi.nlm.nih.gov]
  • "Yaws is a disease neglected even [among] neglected diseases," said Matthew Coldiron, a doctor with medical charity Médecins Sans Frontières, at the meeting.[web.archive.org]
  • Although possibly considered among the most neglected of all neglected diseases during decades, there seems to be now agreement that massive drug administration of the antibiotic azithromycin, coupled with adequate surveillance of foci of transmission[ncbi.nlm.nih.gov]
  • […] and Typing Laboratory, Laboratory Reference and Research Branch, Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA. 5 German Primate Center, Leibniz-Institute for Primate Research, Pathology Unit, Working Group Neglected[ncbi.nlm.nih.gov]
  • Affiliations Department of Control of Neglected Tropical Diseases, World Health Organization, 20 avenue Appia, 1211 Geneva 27, Switzerland. Retired, Lomé, Togo.[web.archive.org]
  • If you can't eradicate yaws, you can forget these other diseases.”[web.archive.org]
  • Forget about it!” This must be a recurrent thought for many of those dealing with neglected tropical diseases, and certainly has hovered in the mind of WHO officials for quite a long time.[web.archive.org]
  • […] foreshores foreshowed foresights forespeaks forespoken forestages forestalls forestland forestries foreswears foretasted foretastes foreteller foretokens foretopman foretopmen forewarned forfeiters forfeiting forfeiture forfending forgathers forgetters forgetting[findmeaword.net]
  • If there is swelling around the nose, a person with late yaws can have headaches, nasal discharge. The faces of people with late yaws can develop an appearance called goundou.[drugs.com]
  • Not only do we have to worry about the regular three headaches such as deforestation, poaching and fatal pathogens like Ebola; but now conservation efforts are impacted because this new pathogen is affecting reproduction and gorilla social group cohesivity[primatology.net]
  • Nervous symptoms have never been noticed, if indefinite findings such as headache, backache and pain in the calves may be excluded. Minor changes in the spinal fluid have been found, but this work has only been begun.[jamanetwork.com]
  • In order to overcome political apathy, moving rapidly ahead and getting momentum, the new campaign will need, the sooner the better, to receive the World Health Assembly's endorsement (the last WHA resolution, WHA 31.58, on yaws and other endemic treponematoses[web.archive.org]


One component of the patient assessment is the history of the individual which includes any contacts or exposures. Additionally, healthcare workers should consult the WHO clinical pictorial guide to help identify the infection. Further workup includes laboratory studies.

Laboratory tests

Serological tests are commonly used to confirm treponemal infection, however, they do do not differentiate yaws from syphilis. Hence, the clinician should correlate the clinical picture, the epidemiology, and the laboratory findings to arrive at the diagnosis.

The studies include: 1) rapid plasma reagent (RPR), 2) Venereal Disease Research Laboratory (VDRL), 3) fluorescent treponemal antibody absorption (FTA-ABS), 4) T. pallidum immobilization (TPI), and 5) T. pallidum hemagglutination assay (TPHA).

The RPR and VDRL tests are persistently reactive through all the stages. Specifically, they generate positive results as early as 2 to 3 weeks following the presentation of the mother lesion.

There two types of rapid tests that produce the point-of-care (POC) diagnosis [8]. The rapid treponemal tests are widely utilized for the diagnosis of syphilis cases while the rapid dual treponemal and non-treponemal POC test distinguishes the antibodies of yaws from syphilis. It is used in various countries including Ghana, Papua New Guinea, Solomon Islands and Vanuatu to eliminate the disease.

Polymerase chain reaction (PCR) [9] is used to confirm the disease and also to identify resistance to azithromycin.


A biopsy of the lesions can be obtained for histopathologic analysis [10].

Streptococcus Pneumoniae
  • pneumoniae : a cluster-randomized clinical trial, PLoS Med, 2010 , vol. 7 pg. e1000377 37 A prospective study of the impact of community-based azithromycin treatment of trachoma on carriage and resistance of Streptococcus pneumoniae, Clin Infect Dis,[cid.oxfordjournals.org]
  • The potential effect of mass treatment with azithromycin on resistance in Streptococcus pneumoniae may impact the management of acute respiratory infections in children.[web.archive.org]


The therapy of this infection includes antibiotic treatment. One option is azithromycin, which is prescribed as a single oral dose at 30mg/kg. The maximum is 2 g. Additionally, the drug of choice is benzathine penicillin, which is administered intramuscularly as a single dose of 600, 000 units in children. This dose is doubled in adults. The lesions become non-contagious 24 hours after penicillin treatment. Furthermore, healing occurs within 1 to 2 weeks.

There are alternatives for penicillin-allergic patients such as tetracycline, erythromycin, or doxycycline [11]. If benzathine penicillin is not available, then oral penicillin can be given for a duration of 7 to 10 days [12].

There are treatment guidelines depending on the epidemiologic profile. For example, in communities where more than half of the children are seropositive, then the entire population warrants treatment. When 10% to 50% are seropositive, then all children of ages 15 or under should be treated in addition to the affected individuals and their contacts. Finally, if below 10% of children are seropositive, then treatment is indicated for household members, contacts and infected individuals.


Approximately 10% of untreated patients suffer from disfigurement of the nose and legs in the late stage. This destruction phase results in disabilities that affect their quality of life. Furthermore, some patients will have neurologic and ophthalmologic manifestations.

Untreated patients may have relapses even after 5 to 15 years. During these relapses, the infection targets the skin, bones, and joints.

Note that while the lesions can spontaneously resolve, secondary bacterial infections and scarring are frequently observed.


The organism responsible for yaws is Treponema pallidum subspecies pertenue. This spirochete bacterium is serologically identical to T pallidum, which causes syphilis.

The mode of transmission of yaws is through person-to-person contact, particularly in children who spread the infection through the contact of skin-to-skin or skin- to-mucous membrane.

Note that yaws is not a sexually transmitted infection, nor is it congenital. It is not observed in the urban setting either.


Geographical distribution

Six decades ago, yaws was found in all tropical areas and Africa demonstrated the highest prevalence according to reports by the World Health Organization (WHO) in the 1990s. India announced the eradication of the infection in 2006.

Yaws occurs in tropical forest regions in Africa, Asia, Latin America and the Pacific. Specifically, it is observed in impoverished and overpopulated communities in hot and humid areas.

In 2010, the WHO highlighted that yaws is still common in poor communities and populations. Moreover, it is endemic in Indonesia, Timor-Leste, Papua New Guinea, the Solomon Islands, as well as the African countries of Cameroon, Central Africa Republic, Congo, the Democratic Republic of the Congo, Ghana, Sierra Leone, and others as well.

Patient demographics

Approximately three quarters of infected individuals are younger than 15 years of age and especially in the ages of 6 to 10. In fact, it is believed that there are 34 million people at risk for infection, in which 23 million are less than 15 years of age and the remaining are between 16 and 24 years old.

With regards to gender, there is no preference.

Sex distribution
Age distribution


This infection is transmitted when minor skin cuts or abrasions on an unaffected person come into contact with fluid from skin lesions of affected patients. Furthermore, yaws is seen frequently on the extremities.

The incubation period ranges from 9 to 90 days. T. pallidum pertenue enters the subcutaneous lymphatic system and disseminates throughout the body. Yaws occurs in two stages: infectious and non-infectious.


This is the early phase, in which the lesion appears as a papilloma that marks the entry site of the organism. This circular, swollen lesion is filled with the spirochetes. Due to hematogenous dissemination, lesions can present everywhere. They typically remain for 3 to 6 months and heal spontaneously. Early yaws may be associated with bone pain and lesions.


The late stage occurs 5 years after the primary infection. The main features are deformities of the nose and bones, as well as thickening of the palms and soles. Due to the latter, patients experience difficulty when walking.


The key preventative strategies for yaws is health education and implementation of good hygiene.

Note that measures are being undertaken to eradicate the disease, especially through early diagnosis and prompt treatment of active cases. Furthermore, there is targeteted therapy of communities and populations. 


Yaws is the most common infection in the group referred to as endemic treponematoses, which also includes bejel and pinta. The agent responsible for yaws is Treponema pallidum subspecies pertenue, which is transmitted through skin-to-skin contact in individuals typically less than 15 years of age. Furthermore, the disease is frequently observed in poor, unsanitary conditions in tropical areas with hot and humid climates, as well as frequent rainfalls [1].

This infection typically presents as a skin lesion that may disseminate if left untreated. In advanced disease states, yaws affects the skin, bones, and joints; untreated patients may develop physical handicaps and disfigurement [2]. Overall, yaws is a chronic disease that may relapse [3] [4] [5].

Diagnosis is based on a full evaluation including the patient's history and any exposures or contact risks. There are various serologic tests, although certain techniques may not differentiate between yaws and syphilis. Therefore, the diagnosis is determined through assessment of the clinical findings, epidemiology of yaws, and positive laboratory testing.

Therapy consists of either benzathine penicillin or azithromycin. Furthermore, there are guidelines regarding the treatment of the community and population in addition to infected individuals.

The ultimate therapeutic goal is to eradicate yaws, which can be accomplished with early diagnosis and treatment. Other preventative measures include education and practicing good hygiene.

Patient Information

Yaws is a long-term bacterial infection involving the skin, bones, and joints. The bacterium responsible for this disease is called Treponema pallidum pertenue, which is in the same family as the bacteria that causes syphilis. However, yaws is not transmitted sexually. It is transmitted when a scratch, abrasion, or bite comes into contact with a lesion or fluid from a lesion of an affected patient.

This disease primarily infects children under 15 years old in impoverished and overcrowded hot and humid tropical regions in Asia, Africa, Latin America, and the Western Pacific islands.

Approximately 2 to 4 weeks after infection, the patient develops a skin lesion known as "mother yaw" typically on the leg. It may be itchy and, if scratched, the infection may spread to other sites of the body.

The healthcare worker will assess the history and any possible exposures to the disease such as household members, classmates, etc. Also, the healthcare worker will examine and evaluate the lesion. Finally, there are blood tests that will help the medical team to make the diagnosis.

The treatment for this infection is penicillin. Additionally, the clinician will determine who else will need treatment including all exposures (household members, classmates, etc). Early diagnosis and treatment are necessary to finally eliminate this disease.

One of the key ways to prevent this disease is through health education and practicing good hygiene.



  1. Lupi O, Madkan V, Tyring SK. Tropical dermatology: bacterial tropical diseases. Journal of the American Academy of Dermatology. 2006;54(4):559-78; quiz 578-80.
  2. Antal GM, Lukehart SA, Meheus AZ. The endemic treponematoses. Microbes and Infection. 2002;4(1):83-94.
  3. Koff AB, Rosen T. Nonvenereal treponematoses: yaws, endemic syphilis, and pinta. Journal of the American Academy of Dermatology. 1993; 29(4):519-35; quiz 536-8. [Medline].
  4. Sanchez MR. Endemic (Nonvenereal) Treponematoses. Freedberg IM, Eisen AZ, Wolff K, Austen F, Goldsmith LA, Katz S, eds. Fitzpatrick's Dermatology in General Medicine. 6th ed. New York, NY: McGraw-Hill; 2003.
  5. Yaws eradication: past efforts and future perspectives. Available at http://www.who.int/bulletin/volumes/86/7/08-055608/en/. Accessed: July 30, 2012.
  6. Mitjà O, Hays R, Ipai A, et al. Outcome predictors in treatment of yaws. Emerging Infectious Diseases. 2011;17(6):1083-5.
  7. Etymologia: yaws. Emerg Infect Dis. 2011 Jun. 17(6):1082.
  8. Ayove T, et al. Sensitivity and specificity of a rapid point-of-care test for active yaws: a comparative study. Lancet Global Health, 2014; 2(7): e415–e421.
  9. Chi KH, Danavall D, Taleo F, et al. Molecular differentiation of Treponema pallidum subspecies in skin ulceration clinically suspected as yaws in Vanuatu using real-time multiplex PCR and serological methods. American Society of Tropical Medicine and Hygiene. 2015;92(1):134-8.
  10. Engelkens HJ, ten Kate FJ, Judanarso J, et al. The localisation of treponemes and characterisation of the inflammatory infiltrate in skin biopsies from patients with primary or secondary syphilis, or early infectious yaws. Genitourinary Medicine. 1993; 69(2):102-7.
  11. Farnsworth N, Rosen T. Endemic treponematosis: review and update. Clinical Dermatology. 2006; 24(3):181-90.
  12. Scolnik D, Aronson L, Lovinsky R, et al. Efficacy of a targeted, oral penicillin-based yaws control program among children living in rural South America. Clinical Infectious Diseases. 2003; 36(10):1232-8.

Ask Question

5000 Characters left Format the text using: # Heading, **bold**, _italic_. HTML code is not allowed.
By publishing this question you agree to the TOS and Privacy policy.
• Use a precise title for your question.
• Ask a specific question and provide age, sex, symptoms, type and duration of treatment.
• Respect your own and other people's privacy, never post full names or contact information.
• Inappropriate questions will be deleted.
• In urgent cases contact a physician, visit a hospital or call an emergency service!
Last updated: 2019-07-11 22:56