Milker’s nodule are itchy professional dermatosis of viral etiology that occurs in patients who come into contact with infected animals. Clinically manifested by a nodular rash on the background of unchanged skin. Primary elements of a pinkish hue with a diameter of up to 1 cm, have the shape of a hemisphere, have a tendency to peripheral growth. In the center of the nodules there is an indentation, painful when pressed. Spontaneous self-resolution of the process is possible. The diagnosis is made on the basis of anamnesis, the establishment of the fact of working with an infected animal, clinical manifestations and the results of histological examination. Disease do not require special therapy, antiviral ointments and antiseptics are used to accelerate the resorption of the rash.
General information
Milker’s nodule is one of the varieties of a group of professional dermatoses of infectious genesis that occur when patients work with sick animals. The Austrian doctor V. Vinternitz was the first to introduce the term “milker’s nodule” into dermatology in 1899. In practice, he established the connection of skin manifestations with the work of patients, proving that the cause of pathological changes was the contact of milkmaids with sick animals. The German microbiologist V. Frybus in 1914 named the cowpox virus as the cause of the milker’s nodule. Currently, most dermatologists believe that the disease is caused by the Strongyloplasma paravaccina virus.
The reservoir of the pathogen in nature are calves and dairy cows. People become infected through direct skin contact. There is no data on cases of human-to-human transmission of the virus in the scientific literature. The milker’s nodule are found in places where cattle, pigs and goats are raised. Milkmaids, slaughterhouse workers, and cattle breeders suffer. Due to the professional factor, pathology has a gender coloring – women are more likely to get sick. The urgency of the problem is due to the prevalence and contagiousness of the milker’s nodule.
Causes
The cause of the disease is a paraspenic virus of the poxvirus family, which is different in its antigenic properties from the cowpox virus. The causative agent of the milker’s nodule was discovered in the laboratory by fixing oval corpuscles in the cytoplasm of the affected cells, resembling the smallpox virus of cows and sheep. Paraospenic virus is an antigen that, getting on the skin with direct human contact with the udder of a sick animal, violates the protective barrier of the skin, penetrates into the dermis. Contribute to the introduction of antigen abrasions on the surface of the skin.
With the development of milker’s nodule in the cells of the upper layers of the skin, a protective antigen-antibody reaction begins, local (cellular) and general (humoral) immunity is activated. Indirectly, through T-lymphocytes and macrophages, an inflammatory reaction is triggered in the dermis. In parallel, the affected epidermal cells begin to produce pro-inflammatory cytokines and interleukins, which not only stimulate inflammation, but also accelerate proliferative processes in the skin. Visually, there is a rash of the primary elements of the pathological process in the form of nodules.
Symptoms
The disease occurs subacute after contact of patients with sick animals. The incubation period usually does not exceed a week. Primary elements in the form of spots, against which hemispherical flesh-colored nodules with a diameter of 2 mm to 1 cm with an inflammatory corolla along the periphery are formed, appear initially on the skin of the hands or on the wrist. The nodules of the milkers are convex, with clear contours, dense to the touch. Primary elements tend to peripheral growth. They spread quite quickly to neighboring areas of healthy skin, occupying the forearms, cheeks, nose, corners of the mouth, interdigital spaces. Increasing, the nodules of the milkmaids change color from pale pink to purple-cyanotic. In the center of the nodules, a vesicle filled with serous contents appears first, and then an indentation, painful when pressed.
The nodules of the milkmaids itch, scratching occurs on the skin, a secondary infection joins. Regional lymph nodes are involved in the process, lymphangitis phenomena are observed. The healthy skin surrounding the nodules of the milkers remains inert. The involution of primary elements occurs within 2 weeks, but sometimes takes up to 2 months. Nodules ulcerate in the center, are covered with a crust, which disappears, revealing an erosive surface. Wetness is replaced by granulations that do not leave a scar.
Spontaneous regression of nodular rash is possible, but pigmentation always remains in its place. Subjective sensations are absent, rarely the pathological process is accompanied by a slight subfebrility, allergic rashes appear, disappearing as the underlying disease regresses. Patients with milker’s nodule are not allowed to work with healthy animals until the complete involution of the primary elements. The milker’s nodule leave behind lifelong immunity.
Diagnosis and treatment
The clinical diagnosis of the pathological process is made by a dermatologist or a professional pathologist on the basis of an epidemiological history establishing contact between the patient and a sick animal, and typical symptoms of the disease. The diagnosis is confirmed histologically. With milker’s nodule in the epidermis, the phenomena of balloon degeneration, intracellular inclusions, intraepidermal cavities in the thorny layer are clearly visible. Parakeratosis, acanthosis is clearly visible. Under the epidermis, a polymorphic inflammatory infiltrate with the phenomena of fanuloma is determined, which consists mainly of epithelial cells, Pirogov-Langhans cells, foreign bodies and lymphocytes. Dilated blood vessels are fixed. Differentiate milker’s nodule with vulgar warts, pyogenic granuloma, warty and papulonecrotic tuberculosis of the skin, true cowpox, vaccine rashes.
The milker’s nodule do not require special therapy due to autosanation and ease of flow. Externally, if necessary, aniline dyes (for example, diamond green), antiviral and antibacterial ointments, gels, sprays are used. Wet bandages with antiseptic solutions are applied to extensive lesions, which simultaneously protect the hands from possible injury and secondary pyogenic infection.
Prevention of milker’s nodule consists in isolating infected patients and infected animals, observing epidemiological and sanitary conditions, as well as following generally accepted rules of personal hygiene (washing hands with disinfectant soap or antiseptic solutions before and after contact with animals). On livestock farms, slaughterhouses, stockyards, it is necessary to carry out proper veterinary supervision of animals, their vaccination. The prognosis for nodules of milkmaids is favorable.
