Yaws: The long challenging path towards eradication
India has achieved breakthrough public health milestones in the past by eradication of smallpox and guinea worm disease. There has been a concerted effort to target other diseases in the country which are amenable to eradication/elimination. One such disease, yaws has been the target since decades and particularly after the inception of yaws eradication programme (YEP) since 1996-97.
Yaws belongs to a group of chronic bacterial infections (endemic treponematoses, non-venereal spirochete diseases) caused by treponemes. The organism responsible for yaws is Treponema pallidum subspecies pertenue. It is morphologically and immunologically identical to T. pallidum (the organism that causes venereal syphilis). Other diseases belonging to this group are bejel (endemic syphilis) and pinta. Yaws is the most common among these three 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.
It is usually prevalent among the people living in primitive, unhygienic conditions in hot and humid areas like those found in tropical countries. In India, this disease was a scourge for poor, most marginalized and difficult to reach population living in remote, hilly, forested areas of the country and particularly affected the tribal population. The infection put these marginalized population at a further disadvantage because of morbidity, disability & economic burden associated with the disease.
Mode of transmission
Yaws is transmitted by direct (person-to-person) contact with the exudates and serum from infectious lesions. The total duration of infectiousness for an untreated yaws patient, including relapse is probably of the order of 12-18 months.
After the bacterium has "penetrated" into the skin, within a period of 3 to 4 weeks (with a range from 10 to 90 days), early lesion appears near the infection. Early secondary lesion appears usually after an interval of 6-16 weeks (or even upto 2 years) of the primary lesion. Yaws most commonly occurs in young children is characterized by a primary skin lesion (Early Yaws). It starts as a small papule, but reaches up to 5 cm in diameter, becomes lifted, is often ulcerated, and may resemble a raspberry. Papilloma is the most common presentation and is often pruritic facilitating spread of the infection to other areas of the body by scratching. These lesions may persist for 3-6 months and heal spontaneously, often leaving a scar.
The early secondary skin lesion is papular and may occur any time from 4 to 12 weeks after the initial infection. The rash covers the limbs, neck, and buttocks and may spread onto the body. It is at this stage that the serological tests become positive. Nocturnal bone pain and tenderness of the tibia and other long bones due to periostitis are common and may persist for up to 6 months.
Usually after 5 years of onset of illness, destructive lesions of the skin, bone and cartilage (Late yaws) may appear which are non-infectious but may result in disabilities like gangosa and pathological fractures.
Yaws simulates the lesions of scabies, impetigo, skin tuberculosis, tinea versicolor, tropical ulcer, leprosy and psoriasis. The yaws may also coexist with any of these lesions. There is no natural immunity.
Most latent and incubating cases are found in clusters around an infectious case and can usually be diagnosed by epidemiological tracing. Serological tests to detect treponemal antibodies can be useful in diagnosis of yaws only if sexual transmitted syphilis is excluded. In field situation, these tests support a clinico-epidemiological diagnosis of yaws but are not as specific as the dark-field examination. 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.
Sub-species of Treponema pallidum, i.e., Treponema pallidum
subsp. pallidum, Treponema pallidum subsp. pertenue, and Treponema pallidum subsp. endemicum cannot be serially cultured in vitro, are indistinguishable by dark-field microscopy. However, sub-species specific genetic signatures permit molecular differentiation using methods that involve polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and DNA sequencing of specific treponemal DNA sequences. Real-time polymerase chain reaction (RT-PCR) has been proved to be very efficient in molecular differentiation among all subspecies of treponemes. It is very fast, highly sensitive and highly specific assay.
Single dose of injection benzathine benzyl Penicillin was the treatment of choice for both cases and contacts of yaws. In patients allergic to penicillin, erythromycin/ tetracycline was the alternative treatment of choice and India used the same treatment to counter the disease. However, off late WHO recommends use of single dose of azithromycin as the preferred treatment of choice.
Eradication Of yaws
Yaws had potential for eradication owing to the following favorable factors:
· Man is the only reservoir of infection
· Patients with early lesions are the main sources of infection
· Direct contact with secretions of skin lesions is the main mode of transmission; no vector is involved
· “magic bullet” is available for intervention i.e., a single injection of long-acting benzathine benzyl penicillin, which is easily available at low cost, has no toxicity, is stable preparation and is operationally feasible
· Yaws infection was localized to small pockets within the country.
However, the following factors needed active pursuance and action to achieve the target of eradication:
· 5-10 times more latent cases than clinical cases
· No visible lesions during the latent stage, but infectious relapses may occur which can result in new outbreaks
· Frequently re-survey after control to detect remaining cases
· Serological surveillance to establish interruption of transmission of infection.
Yaws: Global Overview
Since the creation of WHO in 1948, the fight against endemic treponematoses (yaws, bejel and pinta) has been a priority for the Organization. A review of historical documents from the 1950s, shows that at least 88 countries and territories within the tropical belt of 20 degrees north and south of the equator were endemic for yaws. Published reports suggest presence of yaws in many parts of the world viz. South East Asia (India, Indonesia, Timor-Leste, Thailand, Sri Lanka), Western Pacific (Solomon Island, Papua New Guinea), Africa (Congo, Ghana, Ivory Coast, Togo), PAHO (Haiti, Eucador) etc
In the period 1952-1964, WHO in close collaboration with UNICEF, launched the global endemic treponematoses control programme (TCP), which became a real success story. More than 50 million patients were treated in 46 countries, reducing the overall prevalence of these diseases by more than 95%. The control strategy subsequently changed from a vertical programme to be integrated into the basic health services. These basic health services were to cope with the remaining “last cases” of endemic treponematoses in the community until eradication has been achieved. The goal of eradication was not attained due to the complacency following gradual dismantling of the vertical programmes & premature integration of yaws control activities into weak/ non-existent primary health-care systems in yaws endemic areas and disappearance of the resources and commitment for yaws control. A number of foci of transmission remained and by the end of the 1970s a resurgence of the endemic treponematoses had occurred in many areas of the world. The necessity for renewed efforts was recognized by the World Health Assembly and expressed in WHA Resolution 31.58. In 1995, WHO estimated that 460,000 infectious cases of yaws occurred worldwide: 400,000 in West and Central Africa; 50,000 in South-East Asia and the remainder in other tropical regions.
Yaws: Indian scenario
In India, there was a paucity of literature on yaws. Reports suggest that the first cases of yaws were reported from among tea plantation workers in Cachar district of Assam in 1887. The disease was later detected in states of Orissa, Chhattisgarh, Madhya Pradesh and other areas.
In India, the disease is mostly known by the name of the tribes which are mostly affected by yaws in any region. For example, the disease is called ‘Madia Roga’ and ‘Gondi Roga’ in Maharastra and Madhya Pradesh. Some synonyms of yaws are based on its clinical features e.g. it is called ‘Domaru Khahu’ in Assam which indicates a fig like eruption. ‘Chakawar’ is a term used for chronic ulcers so commonly seen in Central India and part of Uttar Pradesh.
The disease was reported from the communities living in hilly and forested areas in the tribal inhabited districts in states of Chhattisgarh, Odisha, Andhra Pradesh, Telangana and Maharashtra. Madhya Pradesh, Tamil Nadu, Assam, Jharkhand, Uttar Pradesh and Gujarat are other states from where cases had been reported earlier.
During 1952-1964 mass campaign were launched with assistance from WHO and UNICEF in the States of Orissa, Madhya Pradesh, Maharashtra, Andhra Pradesh and Madras (now Tamil Nadu) and about 0.2 million cases were detected from these states. The strategies adopted were house-to-house survey in the villages to identify cases followed by selective mass treatment of all cases, their household and other contacts with a single injection of PAM (Penicillin G in oil with 2% aluminium monostearate). This resulted in marked reduction of yaws cases in India and disease prevalence was brought down from 14.0 per cent to below 0.1 per cent in many areas. Following this dramatic decline in disease transmission, active anti-yaws activities were abandoned in the majority of the States. In 1977, yaws resurgence occurred in Madhya Pradesh. In 1981, the National Institute of Communicable Diseases (NICD), Delhi undertook a rapid survey to assess the situation; wherein A total of 18,196 individuals from three districts of Orissa, one district of erstwhile Madhya Pradesh, Maharashtra, Andhra Pradesh were examined and twenty-six cases were detected, six of them serologically positive, indicating continuing yaws transmission in some areas of the country. In 1985, NICD collected information using mailed questionnaire method from various districts of five states (Andhra Pradesh, Madhya Pradesh, Orissa, Maharashtra and Tamil Nadu). The data suggested that problem of yaws continued to linger on in India albeit at a low level. In 1995, NICD prepared a project document on Yaws Eradication Programme in India, which was approved by Government of India for initiating the yaws Eradication Programme (YEP) in Koraput district (undivided) of Orissa and was then expanded to cover all the eleven yaws endemic states of the country.
The objectives of the programme were to achieve:
v Cessation of transmission of yaws in the country (defined as nil reporting of new yaws cases) and
v Eradication of yaws defined as absence of new cases for a continuous period of three years, supported by absence of evidence of transmission through sero-survey among under-five children (i.e. no sero reactivity to RPR/VDRL in <5 yr children).
The programme strategy adopted to achieve these objectives:
· Creating yaws consciousness and awareness in health professionals and community members,
· Trained manpower development,
· Detection and treatment of cases and contacts,
· Monitoring and evaluation, and
· IEC activities harnessing multi-sectoral approach.
A high-level National Task Force (NTF) was established under the chairmanship of DGHS for undertaking periodic reviews and for monitoring the progress in implementation and to advice on Annual Plans of the action. The programmes was subjected to independent appraisal frequently and in all Six Independent Appraisals of the programme were undertaken since the beginning of YEP.
After years of continuous fight against yaws, the last case was reported in India in October, 2003. The Zero incidence of yaws cases was validated by eminent experts and based on recommendations of the task force the disease was finally declared as eliminated by Honorable union health & FW minister at Vigyan Bhawan on 19th September 2006.
Yaws: Journey from Elimination to Eradication
Subsequently, India embarked upon the journey for eradication of yaws from India.
In post elimination phase apart from ongoing activities three new activities were started:
· Sero-survey among children to assess cessation of transmission of infection for 3-5 years
· Rumour reporting
· Investigation and cash incentive scheme to encourage voluntary reporting of the cases by the community.
Based on the recommendation of the sixth independent appraisal, the seventh Task force meeting on YEP under the chairmanship of DGHS on 25th July, 2014 recommended seeking Yaws eradication status for India.
Following this WHO was approached for certification of Yaws eradication. In this context, WHO sent an international Verification team (IVT) of experts for assessment of yaws free status of India during 4–17th October, 2015. Based on the recommendations of the IVT, WHO Director General declared India free of Yaws at Geneva on 5th May, 2016.
A celebratory function was organized to mark the end of Yaws from India on 14th July, 2016 at National Media Center, Raisina Road, New Delhi.
The Honorable Union Health and Family Welfare minister Mr. Jagat Prakash Nadda was the Chief Guest and Honorable Minister of State for Health and Family Welfare, Ms. Anupriya Patel was the Guest of Honor in the event. Several other dignitaries including the Secretary (Health and Family welfare), Director General of Health Services, Regional Director of WHO South East Asian Region, Additional Secretary (Health) and Mission Director National Health Mission, Director NCDC and Mr. James from UNICEF graced the occasion. The function was also attended by officials from the ministry of health and family welfare, Govt. of India and special invitees from local administration, district & state health officials and NGOs working in the erstwhile yaws endemic states in India.
The Honorable Union Minister of Health and Family Welfare formally declared India as free of Yaws in presence of the august gathering in the function. He lauded the dedicated and concerted effort of health authorities of endemic states/districts in implementing and monitoring the Yaws Eradication Programme under the able leadership of the National Centre for Disease Control, the national nodal agency for the Yaws eradication programme.
The dignitaries also released a monograph titled “YAWS DISEASE-END OF SCOURGE IN INDIA”.
The Union Health Minister expressed his gratitude to all who worked tirelessly to make the endeavor of yaws eradication a reality.
Declaration of yaws Free India (14 July, 2016)