Frambesia

Yaws (synonym: tropical syphilis) is the most widespread highly contagious treponematosis, in which, in addition to the skin and mucous membranes, the skeletal system is also involved in the pathological process.

The name of the disease comes from the French word framboise - "raspberry", since in typical cases the rash looks like a raspberry. The prevalence of yaws in different countries of Southeast Asia, Africa and Latin America varies from 2 to 30-40%. These figures concern manifest forms, while the number of latent cases is approximately 3 times higher.

Epidemiology of yaws

Yaws has distinct epidemiological features: it is usually found in warm and humid climates and is extremely rare in mountainous and desert areas. Infection occurs through direct contact, usually through everyday contact and very rarely indirectly - through household items. Sexual transmission of infection is insignificant compared to syphilis (no more than 2%). The routes of infection are determined by the age of the sick: up to 80% of them are children. Transmission of infection is facilitated by poor sanitary and living conditions (especially overcrowding), low general cultural level of the population, and poor personal hygiene. The entry points for infection are damage to the skin and mucous membranes - bruises, scratches, insect bites. Susceptibility to infection is determined by age factors: it is insignificant up to 1.5 years, reaches 50% by the age of 5 and is maximum (up to 90%) by the age of 15. In adults, yaws is quite rare, and they usually become infected from sick children. Mechanical transmission of the infection by insects (ticks, flies, cockroaches) is allowed. The possibility of intrauterine transmission is denied (reliable cases of congenital yaws are not reported). Infection of monkeys and rabbits has been obtained in experiments.

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Causes of Yaws

The causative agent is Treponema pertenue, discovered in 1905 by Castellani. Incidentally, in the same year, the causative agent of syphilis, pale treponema - Treponema pallidum, was discovered, with which T. pertenue has a complete morphological property (length, mobility, steepness and number of curls, corkscrew shape). When examined under a microscope in a dark field, both treponemas cannot be distinguished from each other. Differences, very insignificant, were revealed only by electron microscopy.

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Symptoms of Yaws

Yaws has a staged course. The incubation, primary, secondary and tertiary periods of the disease are distinguished.

The incubation period usually lasts 3-4 weeks. Sometimes at the end of it the following symptoms of yaws are observed: general weakness, headaches, arthralgia, morning fever. The prodromal phenomena are more pronounced, the younger the child.

The primary period begins with the appearance of the first clinical symptom at the site of the pathogen's introduction - a small, usually single, pale pink, itchy papule, in the center of which a small yellow pustule soon forms. Gradually increasing, the purulent focus becomes covered with grayish-pink vegetations occupying its entire surface, which makes it look like a raspberry. The described primary element with subsequent characteristic dynamics is called pianoma (from "pian" - one of the many synonyms of yaws). Soon, due to the process of neurotization at the base of the pianoma, it is transformed into a superficial ulcer with a foul-smelling, scanty serous-purulent discharge, gradually drying into a crust.

Unlike the hard chancre in syphilis, palpation of the base of the pyanomas reveals a soft consistency. The pathogen, T. pertenue, is easily identified in the tissue juice from the ulcer.

Pianoma is most often localized on open areas of the skin - on the face (nose, lips, ears), hands. Often, small secondary ulcers of pianoma - satellites - appear around the primary ulcer, which, merging with the "parent ulcer", form larger ulcer surfaces with polycyclic outlines over an extensive common crust.

Regional lymph nodes are painful, moderately enlarged, and sometimes regional lymphangitis is clinically distinguishable in the form of a painful inflammatory cord.

Pianoma is a very persistent formation and can persist for weeks and months. However, it gradually scars, the infiltrate is absorbed, and in its place there remains a whitish atrophy area.

Secondary period. Yaws develops over several weeks against the background of resolving pyoma. During this period, generalization of the infection is clearly expressed: numerous itchy rashes appear on the trunk and limbs in the form of erythematous-squamous spots, papules, vusiculopustules, ulcerations, most of which, due to the presence of vegetation on the surface, acquire a resemblance to raspberries. These rashes are called frambesides. They are located in isolation or in groups, the elements of which, when merging (especially in large folds), form extensive "condylomatous plaques" in the form of arcs and rings.

The average lifespan of frambesides is about 2-3 months. After their resorption, areas of superficial whitish atrophy remain.

In later stages of the secondary period, the appearance of “lupoid frambesides” is possible, which are essentially soft tubercles with subsequent ulceration and the formation of disfiguring scars, often leading to elephantiasis and contractures.

Sometimes, pronounced insular and diffuse keratodermas are observed - hyperkeratosis on the palms and soles with deep, painful cracks, forcing patients to waddle from foot to foot while walking, leaning on the outer edges of the feet ("crab gait").

In later stages, polyadenitis may appear.

In addition to the skin, frambesides can appear on the mucous membranes (on the palate, in the oral cavity). Sometimes the nails are involved in the process: they thicken, change color, become deformed and even rejected.

The secondary period usually lasts from several months to two years. The course may be continuous (with old rashes replacing new ones) or wave-like (with alternating attacks of rash and latent periods of the disease, when the symptoms of yaws completely disappear for some time).

Often, in 20-30% of patients, the disease enters its tertiary period (usually after 15-20 years). In the tertiary period, the skin, bones and joints are usually affected. Single or multiple soft nodes (gummas) appear, ranging in size from a walnut to a palm, opening up to form sluggishly scarring, almost painless ulcers, leading to the formation of cicatricial contractures. Synovitis and hydrarthrosis of large joints are noted. The development of fibrous gummas ("periarticular nodules") is possible. Other organs and systems are not involved in the pathological process.

Among the relatively pathognomonic manifestations of the tertiary period of the disease, the clinical symptoms of yaws are described: "gundu" and "gangoza". Gundu (from the local "big nose") is a lesion of the facial bones with increasing headaches, bloody-purulent discharge from the nose with an outcome in tumor-like disfiguring hyperostoses in the area of the nose and cheeks. Gangoza is a disfiguring nasopharyngitis with the development of necrosis of soft tissues and bones in the area of the frontal sinuses and pharynx with an outcome in perforation of the soft and hard palate.

Diagnosis of yaws

The diagnostics of yaws is based on the endemicity of the disease, the characteristic clinical picture, detection of the pathogen in the discharge of the rash elements, positive seroreactions for syphilis (Wasserman reaction, etc.). Serological diagnostics of yaws, in particular, reactions, in comparison with syphilis, are usually positive in a lower titer. Unlike syphilis, yaws is endemic, the main affected contingent is children, infection occurs intra-family household (the primary affect - pyanoma - is localized extragenitally), the rash produces vegetations ("raspberry"), mucous membranes are rarely affected, itching at the sites of rashes is typical, in the late stages, involvement of internal organs and the nervous system is not observed, congenital transmission of infection does not occur.

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Laboratory diagnostics of yaws

Dark-field microscopy and the direct RIF method are used to detect the pathogen in skin lesions. Confirmatory serological reactions used to diagnose syphilis, based on specific ultrasound treponemal antigen (ELISA, RPGA, RIF indirect method), are positive in patients with yaws and bejel.

Treatment of yaws

Treatment of yaws is similar to that for syphilis: penicillin preparations (soluble and durable), reserve antibiotics (tetracycline, erythromycin, sumamed, etc.), local antiseptics (levomekol, miramistin, aniline dyes).

Prevention of yaws

Due to the social nature of the infection, its prevention involves increasing the sanitary culture of the population, improving housing and living conditions, increasing the general well-being of the population, conducting general examinations in endemic zones, mandatory treatment of yaws for all identified patients and all persons who were in close contact with them. Yaws should be monitored by WHO bodies.