Yaws is a chronic contagious non-venereal disease, belongs to a group of chronic bacterial infections (endemic treponematoses, nonvenereal spirochetal diseases) caused by treponemes. (Other diseases belonging to this group are bejel (endemic syphilis) and pinta). Yaws is the most common of all and occurs primarily in the warm, humid and tropical areas of Africa, Central and South America, the Caribbean, Indian peninsula and the equatorial islands of South-East Asia.
Yaws is caused by Treponema pallidum subspecies pertenue. Yaws is not a fatal disease, but causes disabilities and visible deformities of the face and extremities contributing to stigma and discrimination. It affects the skin, bone and cartilage; if left untreated it can lead to deformities of the nose and bones of the leg. However, the disease can be cured and prevented by a single dose of antibiotics.
In India cases were first reported among tea plantation labourers in Assam in1887. Later on cases occurred in Orissa, Chattishgarh, Madhya Pradesh and other areas.
In India the disease is mostly known by the name of the tribes affected most in any region. Thus for example, the disease is called ‘Madia Roga’ and ‘Gondi Roga’ in Bastar area of Chattishgarh and Sironcha area of Maharashtra respectively and ‘Koya rogam’ in Andhra Pradesh and Orissa. Some synonyms of Yaws are based on clinical features like ‘Domaru Khahu’ in Assam which indicates fig like eruption. Chakawar is a term used for chronic ulcers in Central India and part of Uttar Pradesh.
The disease was reported from tribal inhabited districts in states of Chattishgarh, Orissa, Andhra Pradesh and Maharashtra. Cases of Yaws were also reported from Madhya Pradesh, Tamilnadu, Assam, Jharkhand, Uttar Pradesh and Gujarat.
The disease has been eliminated from India in 2006 as no new yaws case has been reported after 2003 in the country. It has long been considered by World Health Organization (WHO) that Yaws can be eradicated because humans are the only reservoir.
Eradication of Yaws in India is possible because man is the only reservoir of infection; a single injection of long acting penicillin was effective; infection was localised to small pockets and; no case has been reported after 2003.
There are two basic stages of yaws: early (infectious) and late (non-infectious).
In early yaws, an initial papilloma (a circular, solid swelling on the skin, with no visible fluid) develops at the site of entry of the bacterium. This papilloma is full of organisms and may persist for 3–6 months followed by natural healing. Nocturnal bone pain and bone lesions may also occur in the early stage. These primary skin lesions (Early Yaws) usually occur in children and adolescents in endemic areas.
Late yaws appears after 5 years of the initial infection and is characterized by disfigurement of the nose and bones, and thickening and cracking of the palms of the hand and soles of the feet. These complications on the soles of the feet make it difficult for patients to walk. Late yaws are non-infectious but may make a person disabled.
Yaws recognition booklet for communities, WHO. Available at
Yaws is caused by Treponema pertenue which closely resembles to T.pallidium. It is a slender spirochete that is serologically indistinguishable from the spirochete T.pallidium which causes syphilis. The agents found in the epidermis of the lesions, lymph glands, spleen and bone marrow. The organism rapidly dies outside the tissues.
Reservoir of infection- Man is the only known reservoir of yaws. Clinical lesions relapse 2-3 times or more during the first 5 years of infections and serve as source for new infections. The most latent cases are found in clusters centered around an infectious case. There are frequent relapses in latent cases
Transmission-Yaws is transmitted through direct (person-to-person), non-sexual contact with the fluid from the lesion of an infected person to an uninfected persons through minor injuries. Most lesions occur on the limbs. The initial lesion of yaws is filled with the bacteria. The incubation period is 9–90 days (average 21 days).
About 75% of people affected are children under 15 years old (peak incidence occurs in children aged 6–10 years). Males and females are equally affected.
Overcrowding, poor hygiene and poor socioeconomic conditions favours the spread of the yaws
Yaws simulates the lesions of scabies, impetigo, skin tuberculosis, tinea versicolor, tropical ulcer, leprosy and psoriasis. It may also accompany these diseases. Penicillin treatment is very useful in differential diagnosis because of miraculous relief seen in yaws but not in other skin diseases.
Most latent and incubating cases are found in clusters around an infectious case and can usually be diagnosed by epidemiological tracing.
Standard laboratory-based tests-
Serological tests are widely used to diagnose treponemal infections (e.g. syphilis and yaws). Serological tests cannot distinguish yaws from syphilis and its interpretation on adults in yaws endemic areas (disease constantly present in a particular region) need careful clinico-epidemiological assessment.
Commonly used tests are Venereal Disease Research Laboratory (VDRL) test and the rapid plasma reagin (RPR) test which are inexpensive, rapid and simple to perform. It takes time for sero-positivity to appear after the onset of disease and hence, initial (mother) case may be sero-negative.
Rapid point-of-care tests (medical testing at or near the site of patient care)-Rapid tests allow the point-of-care diagnosis and treatment of patients. There are 2 types of rapid tests:
Rapid treponemal tests are widely used in the diagnosis of syphilis; however, these tests cannot distinguish between present active yaws and past infections. Therefore, its use alone could lead to overtreatment of patients and over-reporting of cases.
New rapid dual (non-treponemal and treponemal) point-of-care syphilis test allows simultaneous yet separate detection of both antibodies. It is now being used in yaws eradication efforts.
Polymerase chain reaction (PCR)- Genomic analysis using polymerase chain reaction (PCR) can be used to definitely confirm yaws, and this test will be very useful in the last phase of the eradication programme. The PCR technique can also be used to determine azithromycin resistance from swabs taken from yaws lesions.
Two antibiotics are recommended for the treatment of Yaws by WHO. Persons having any features/ symptoms suggestive of Yaws in endemic areas should consult nearest Government Health facility for confirmation and treatment of Yaws. India has eliminated Yaws in September 2006, 3 years after the last case was detected. Now the country is aiming to achieve yaws eradication.
The objectives of the Yaws Eradication Programme (YEP) were: (i) Elimination of yaws, defined as zero reporting of cases based on high-quality case searches validated by independent appraisals; (ii) Eradication of yaws, defined as the absence of new cases for a continuous period of 3 years, supported by the absence of evidence of transmission through sero-surveys among children aged 1-5 years.
About 10% of affected people develop deformities of the legs and nose after 5 years if not received treatment. The disease and its complications lead to school absenteeism and prevent adults from farming activities.
Yaws Eradication Programme in India- In 1996, Yaws Eradication Programme (YEP) was launched in India. The programme strategy included: (1) manpower development, (2) case finding (house to house visits by trained para- medical workers), (3) treatment of cases and contacts simultaneously and (4) Information, education and communication (IEC) activities involving multi- sectoral approach (such as inter- sectoral coordination and collaboration between the health and other departments like tribal development deptt., Integrated Child Development Services (ICDS), panchayati raj, forest department and education department were involved in the YEP). 51 districts from 10 states from where yaws cases were reported were included in the programme.
Number of cases declined dramatically since 1996 and last lot of cases were reported during 2003. No new yaws case has been reported after 2003. Accordingly, on Sept 19, 2006, Govt. of India formally declared elimination of yaws from the country. Three new activities viz. sero- survey among children to assess cessation of transmission of infection, rumour reporting & investigation and cash incentive scheme to encourage voluntary reporting of the cases by the community were involved. Rs.5000/- was to be given to a confirmed case and Rs.500/- to the first informer of a confirmed yaws case on voluntary reporting.
Experts also suggested continuing all the activities carried out since the beginning of the programme viz. active case search, routine reporting, training and IEC.
National Centre for Disease Control (NCDC) in collaboration with state health directorates carried out sero- survey for three consecutive years (2009 – 2011) in all the identified villages. All the samples collected were found to be negative for yaws. The programme’s performance was monitored by independent appraisal missions consisting of experts.
Active yaws case search operation was undertaken as per programme guidelines. No confirm case of yaws could be detected during any of the active search after 2003. The last Task Force meeting held in July 2014 recommended initiation of the process to get yaws eradication certificate from WHO.
The discovery in 2012 that a single, oral dose of the antibiotic azithromycin can completely cure yaws has reopened the prospects of yaws eradication.The WHO roadmap on neglected tropical diseases published in January 2012, targets the eradication of Yaws by 2020.
Key points to remember
• Yaws can be cured with a single-dose oral azithromycin
• The disease is transmitted through person to person contact
• It affects mostly children as they often play together
• Untreated, the infection can lead to chronic disfigurement and disability
• Yaws occurs in poor rural communities in Africa, Asia, Latin America and the Pacific
• Health education and improved personal hygiene are essential components of prevention
Jain SK, Thomas TG, Bora D, Venkatesh S, Eradicating Yaws from India: A Summary , J. Commun. Dis. 2014; 46(3): 1- 9.Available from
Narain JP, Jain SK, Bora D, Venkatesh S, Eradicating successfully yaws from India: The strategy & global lessons. Indian J Med Res, 2015 May; 141(5):608-613.Available from http://www.icmr.nic.in/ijmr/2015/may/0514.pdf accessed on 19th November 2015.