India has achieved eradication of two human
scourges, smallpox and guinea worm disease, since independence. National
efforts are now going on to eradicate/eliminate others. One disease, which
is amenable for eradication, is yaws and the disease has been eliminated
from the country in 2006. This disease primarily affects tribal population
living in remote, hilly and forest areas having difficult terrain. It is
responsible not only for great deal of misery to the affected people but
also contributes significantly to the economic strain of the already impoverished
segments of our society.
Yaws 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 characterized by a primary skin lesion (Early Yaws) which usually
occurs in children and adolescents in endemic situation. These lesions
may persist for 3-6 months and heal spontaneously, often leaving a scar.
Nocturnal bone pain and tenderness of the tibia and other long bones due
to periostitis are common. 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 make a person disabled. 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). Yaws is transmitted by direct (person-to-person)
contact with the exudates and serum from infectious lesions.
Yaws simulates the lesions of scabies, impetigo, skin tuberculosis, tinea
versicolor, tropical ulcer, leprosy and psoriasis. It may also accompany
these diseases. Penicillin treatment (drug of choice) 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. Serological tests to detect treponemal antibodies will 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.
Treatment is same for cases and contacts. Penicillin (Injection Benzathine
Pencillin) is the drug of choice. Though reaction to penicillin in tribal
areas is rare but intradermal skin test to detect penicillin hypersensitivity
should be performed in every case. In patients allergic to penicillin,
alternate drugs such as Tetracycline and Erythromycin may be used.
The potential for eradication of yaws exists with the following factors
Man is the only reservoir of infection;
a “magic bullet” is available for intervention i.e., a single
injection of long-acting penicillin, which is easily available at low
cost, has no toxicity and is a stable preparation and;
the infection was localized to small pockets.
No case has been reported after 2003.
The following factors need active pursuance and action to achieve the
target of eradication:
There are 5-10 times more latent cases than clinical cases;
there are no visible lesions during the latent stage, but infectious relapses
may occur which can cause new outbreaks; therefore, after an initial control
effort, communities must be frequently re-surveyed to detect remaining
serological surveillance is needed to establish that transmission of infection
has been interrupted.
Endemic treponematoses can serve as an indicator for the effectiveness
of primary health care. Effective Primary health care services should
lead to the eradication of endemic treponematoses. Where these are still
prevalent, control efforts can be used as a catalyst for developing primary
health care services. Cure and eradication could induce a feeling of great
achievement in workers and considerably enhance their respect in the community.