Yaws is a chronic non–venereal endemic treponematosis with a predominantly contact transmission mechanism. The clinical picture is characterized by lesions of the skin, less often – mucous membranes with the presence of characteristic rashes. At the secondary and tertiary stages, damage to the osteoarticular system is added. When making a diagnosis, the epidemiology of the disease, anamnesis data and clinical manifestations are taken into account. Serological reactions and microscopy of the discharge from ulcers are used from laboratory methods. Treatment is carried out with antibacterial drugs. In parallel, symptomatic therapy is prescribed.
The yawl was first described in 1825. Translated from French framboise means “raspberry”. This analogy was made due to the morphological similarity of the primary element in the initial period of the disease with a berry. Other names are also known, such as tropical syphilis, pian, yavs. The disease is common in the equatorial countries of Africa, Central and South America, the Pacific Islands, Southeast Asia and northern Australia.
Seasonality is not expressed. Children aged 5 to 15 years who live in rural areas in areas of high humidity are more susceptible to infection. The spread of infection is facilitated by a low standard of living with unsanitary conditions, crowding of the population.
The causative agent of yaws is the spirochete Treponema pallidum of the pertenue subspecies, morphologically indistinguishable from the infectious agent in syphilis. It is a gram-negative bacterium with 8-12 small uniform curls, capable of rotational movements around its longitudinal axis. Resistant to low temperatures, inactivated after 15 minutes when heated above 45-55 ° C. The spirochete is sensitive to heavy metal salts and disinfectants in normal concentrations.
The only reservoir and source of infection is a sick person. Infection occurs when the skin of an infected patient with multiple ulcerative defects on its surface comes into direct contact with the skin of a healthy person. The presence of microcracks, cuts, scratches and bites contributes to the ingress of the pathogen into the internal environment of the body. Some authors note the possibility of transmission of infection through common household items and through flies.
The pathogenesis of yaws has not been studied enough. It is believed that at the site of the introduction of the pathogen, its reproduction occurs. Further, with the flow of lymph, the pathogen penetrates into the lymph nodes, lymphadenopathy develops. With further progression of the process, dissemination of the pathogen occurs with the formation of proliferative changes in tissues and the occurrence of delayed hypersensitivity reactions. Violations of cellular kinetics with acanthosis, papillomatosis and hyperkeratosis are observed in the skin. Infiltrated papules, dry papulosquamous spots, ulcers and gummas are formed. It remains unclear why, with morphological and pathogenetic similarity with syphilis, internal organs are not affected by yaws.
The phrambesia is characterized by the stages of the flow. In the absence of treatment, each previous form passes into the next one with or without a latent period. The classification of yaws takes into account the clinical manifestations of the disease, the presence of specific morphological elements on the skin and the time from the moment of infection. There are three stages of tropical syphilis:
- Primary. Develops after the incubation period. Rarely accompanied by general clinical symptoms. The appearance of a chronic chancre or papule is characteristic, followed by ulceration and the formation of vegetations – the so-called maternal yaws. The primary affect disappears after 2-6 months, leaving behind a depigmented scar.
- Secondary stage. Usually occurs 4-5 months after the onset of the disease. The timing may vary, sometimes the secondary stage manifests in the presence of a chronic chancre, sometimes after 2 years from the moment of inoculation. Multiple rashes resembling maternal yaws are revealed, but of a smaller diameter – pianomas. Common symptoms may appear.
- Tertiary stage. It is diagnosed 5-10 years after infection in 10% of patients. Irreversible crippling and disfiguring lesions of bones, joints and cartilage tissue are observed. Gummas and ulcers form on the skin, healing occurs by rough scarring, accompanied by the development of contractures. Some authors point to the possibility of phagedenization.
The incubation period ranges from 10 to 90 days, with an average of about 20 days. The appearance of a single painless infiltrated papule, often accompanied by itching, is characteristic. Usually the papule is localized on the lower leg, less often on the upper limb or on the face. Gradually, the rash erodes, ulcerates, an extensive ulcer forms, painless on palpation – a chronic chancre or maternal yawn. Unlike syphilis, the bottom of the chancre in tropical syphilis is not infiltrated. The ulcer is covered with a yellow-brown crust, which is gradually rejected. At the same time, the bottom is exposed, filled with vegetation resembling raspberries.
The frambesioma is rich in treponemes. The diameter of the metal chancre reaches 10 cm. The presence of satellite papules is possible. The skin affect resolves after a few months, a depigmented scar remains in its place. Of the common symptoms, patients sometimes note an increase in body temperature and arthralgia. The development of regional lymphadenitis is typical with respect to the localization of chancre. Lymph nodes are enlarged, painless on palpation, not soldered together and with the skin.
The onset of the secondary stage is indicated by the appearance of rashes (pianomas) resembling a piano chancre, but smaller, not exceeding 2 cm in diameter. The elements of the rash ulcerate, an exudate containing treponemes is released. In contrast to the piano chancre, pianomas are numerous. Rashes are usually localized around natural openings and in the area of skin folds. Often a rash forms in the area of the palms and soles. Hyperkeratosis occurs, deep cracks form, painful when walking. Patients spare the affected areas of the skin, so their gait acquires a characteristic appearance – “crab gait”.
Dry spotty-squamous papular elements are also found – pianides, which usually do not contain treponemes. Some patients complain of weakness, headaches, arthralgia and bone pain. Lesions of the mucous membranes are usually absent. Sometimes ostitis and periostitis with predominant involvement of the radius and tibia are detected. Ulcerative foci and bone lesions resolve without a trace after a few weeks or months. There is a latent period.
Irreversible deformations of bones and joints are characteristic of the tertiary stage. Gummous purulent nodes appear with the development of extensive deep ulcers. Lesions heal for a long time with the formation of rough scars and contractures. The most typical for this stage is the occurrence of “gundu” – exostoses of the nasal processes of the upper jaw and “gangosis” – disfiguring rhinopharyngitis with necrosis of soft tissues and bones in the frontal sinuses, hard and soft palate. There is a destructive ostitis of the tibia with a deformity of the type of “saber-shaped shins”. Palmar-plantar keratodermia is also characteristic of this period.
Yaws is a disabling disease. Previously, with the widespread spread of tropical syphilis, the most formidable complication was destructive rhinopharyngitis with the destruction of the palate. When the process spreads to the eyelids, their eversion with corneal ulceration is possible. If the eye socket is affected, the eyeball is likely to shift or its direct destruction. Persistent deformities of the skeleton are often formed, reducing the quality of life of the patient. If extensive ulcers occur, there is a risk of secondary infection with the development of purulent complications. Some authors have reported such rare pathologies as myeloneuropathy, aneurysms, and optic nerve atrophy.
During an objective examination, an infectious disease doctor pays attention to rashes of a specific nature of the corresponding localization. An important distinguishing feature of yaws from syphilis is the extragenital localization of maternal yaws. Enlarged painless regional lymph nodes are palpated relative to the classical chancre. Hyperkeratosis of the palms and feet is determined.
The Wasserman reaction, ELISA, and PHR are used for diagnosis. Serological tests give positive results 2-3 weeks after the occurrence of primary manifestations. Specific methods for distinguishing the subspecies of treponemes are being put into practice – an adsorption test with antitreponemal fluorescent antibodies and a microhemagglutination reaction. An important diagnostic method is the study of the discharge from the chancre and piano by dark-field microscopy.
Differential diagnosis is carried out with diseases having similar manifestations:
- frambesiform leishmaniasis;
When localized on the extensor surfaces of the knee and elbow joints, the yaw may resemble psoriasis. Exclude scabies and vegetative pyoderma, as well as arthropod bites and atypical mycobacterial infection.
Antibacterial drugs are used for treatment. According to WHO recommendations, a single intramuscular injection of benzatin penicillin is used. If you are allergic to penicillins, erythromycin, doxycycline or tetracycline are prescribed, the course of taking these drugs is 15 days. In parallel, symptomatic therapy is carried out, including analgesics, treatment of ulcers, opening and drainage of ulcers. In rhinopharyngitis, modern methods of plastic surgery and the latest methods of prosthetics with the installation of special implants are recommended for the correction of cosmetic defects. With the development of complications, appropriate treatment is indicated.
Prognosis and prevention
The prognosis for life with yaws is relatively favorable due to the absence of lesions of internal organs. In the early stages, with timely treatment, complete recovery occurs without the development of irreversible consequences. In the later stages, the ability to work decreases or is lost due to the formation of defects in the musculoskeletal system. If the facial part of the skull is involved in the process with eye damage, blindness may develop.
There is no specific vaccine against yaws. As part of the implementation of the WHO program for the elimination of tropical syphilis, a scheme of antibiotic prophylaxis with penicillin was developed for the population of endemic areas and contact persons. An important component of preventive measures is the improvement of sanitary and hygienic and living conditions.