Hyderabad: India is close to eradicating yet another disease.
On September 19, the country completes the mandatory five-year waiting period for yaws, a skin disease that mostly affects tribal populations, to be declared as eradicated. If everything goes well, yaws will be the third disease to be eradicated in independent India.
India has successfully eradicated two major diseases — smallpox and guinea worm (dracunculiasis). With the success of yaws, health authorities are now encouraged to list another disease — lymphatic filariasis — for elimination by 2015, five years before the deadline of 2020 set by the World Health Organisation.
For a disease to be certified by the WHO as “eradicated”, a country first needs to “eliminate” the disease. Yaws was declared eliminated on September 19, 2006 after there was not a single clinical case for three years since 2003. After a disease is eliminated in a particular country, there should not be any clinical or latent cases for a full five years to earn the disease eradication certificate by the WHO.
In the case of yaws, there have been no case in any part of the country since 2003. And after September 19, 2006, there were no cases of even latent yaws. The mandatory five-year term concludes on September 18 and if there are no fresh cases, India will be eligible to approach the WHO for the yaws eradication certificate.
“A disease is said to be eliminated if the number of cases go down to one or below per 1,000 population. And if the number of cases is zero and there are no fresh cases for the next five years, the disease is said to be eradicated. Yaws now qualifies for the WHO eradication certificate,” said Dr A.K. Mukhopadhyay, in charge of the Rajahmundry unit of the National Centre for Disease Control (NCDC).
He adds that that there could be some delay in getting the certification as health authorities from the districts where the disease was once prevalent are yet to submit their “nil reportage”.
“In Andhra Pradesh, yaws was prevalent in Srikakulam, Vizianagaram, East and West Godavari, Khammam and Warangal districts. We are waiting for reports from the districts. We sent reminders to them earlier this week,” Dr Mukhopadhyay said.
NCDC authorities are now busy conducting “sero surveillance” in these districts in Andhra Pradesh and other states where yaws was once a major health nuisance to rule out even latent cases of the disease.
As part of the exercise, blood samples of all children below five years are tested covering both tribal and non-tribal villages. “So far we have not encountered even a single case. We are keeping a watch on migrant populations too, to rule out fresh cases if any,” Dr Mukhopadhyay said.
It took nearly 15 years for India to win the war against yaws. Though it has been fighting the disease for more than four decades, it was only in the mid-1990s that concerted efforts began to first eliminate and then eradicate the disease.
That India was sincere in its intent was evident from the following statistics. There were 3,571 yaws cases in 1996 and within a year the number of cases came down by five times, to 735 in 1997.
By 2003, the number of cases fell to just 46 and since then not a single case has been reported.
Yaws is a relatively easy disease to eradicate. Man is the only reservoir of infection, a “magic bullet” in the form of a single injection of long-acting penicillin is available, and the disease is highly localised.
After the first stage of elimination, health authorities have been actively looking for latent cases which do not have a clinical manifestation, that is, the person is infected but the symptoms do not appear.
According to an NCDC report, there are five to ten times more latent cases than clinical cases of yaws. Though there are no visible lesions during the latent stage, infectious relapses may occur which can cause new outbreaks.
“After an initial control effort, we are resurveying communities frequently to detect remaining cases. Serological surveillance will establish that transmission of infection has been stopped,” Dr Mukhopadhyay pointed out.
Lymphatic filariasis, which is next to be targeted for elimination, is prevalent in remote tribal dominated villages of West and East Godavari district. It is observed in weavers’ community in these districts. It will take another four years for the disease to be eliminated.
Facts about Yaws
l Yaws is a non-venereal skin disease that mostly afflicts tribal populations inhabiting hilly regions and inaccessible areas. Yaws has a history of just a little over 150 years in India; it was first noticed in tea workers in Assam in the latter part of the 19th century.
l Yaws is caused by Treponema pallidum subspecies pertenue. The disease is transmitted by person-to-person contact. The lesions caused by yaws look like those of skin tuberculosis, leprosy and psoriasis.
l Yaws belongs to a group of chronic bacterial infections and is characterised by a primary skin lesion, which usually occurs in children and adolescents in endemic situations. These lesions may persist for three to six months and heal spontaneously, often leaving a scar. Nocturnal bone pain and tenderness of the tibia and other long bones is common. Usually five years after the onset of the disease, destructive lesions of the skin, bone and cartilage may appear which are non-infectious but may make a person disabled.
l The disease was neglected for long as the victims were mostly tribals and limited to a few districts in a few States. The Yaws Eradication Programme gained momentum after WHO took it up for worldwide eradication. India successfully eliminated yaws in 2006 and now qualifies for WHO’s disease eradication certificate. If this happens, yaws will be the third disease to be eradicated in the last 60 years.
l According to National Centre for Disease Control, yaws was responsible not only for a great deal of misery to the affected people but also contributed significantly to the economic strain of the already impoverished segments of society.