Milkers Node, also known as paravaccinia, is a viral skin disease caused by exposure to the pseudocowpox virus during milking.

bubble_chart Etiology

It is caused by the poxvirus in the cow's udder. Under an electron microscope, the virus appears cylindrical with protruding ends and contains a dense DNA core. This virus can grow and reproduce in bovine tissue cell cultures but, unlike the cowpox virus, cannot grow in monkey or human tissue cells.

bubble_chart Clinical Manifestations

The incubation period is 5 to 14 days. Initially, one or several inflammatory papules appear on the hands and forearms, which later turn into purplish-red hemispherical nodules surrounded by a red halo. The center is umbilicated, firm in texture, about the size of a soybean, with a smooth surface, scattered and non-confluent. Sometimes, there may be a single vesicle or pustule at the top, which later crusts over or gradually develops into a papilloma-like, light-red lesion resembling pyogenic granuloma. The lesions naturally resolve in about 6 weeks without leaving scars. Systemic symptoms are mild, occasionally accompanied by local lymphadenopathy. In some patients, within 1 to 2 weeks of the nodules appearing, papules, papulovesicles, urticaria, and erythema multiforme-like rashes may develop on the hands, forearms, upper limbs, lower limbs, and neck. This is a toxic or allergic reaction that resolves within 1 to 2 weeks.

bubble_chart Auxiliary Examination

Histopathology: The epidermis shows parakeratosis and pseudoepitheliomatous hyperplasia, with multilocular vesicles visible in the stratum spinosum. Viral inclusion bodies can be found in the cytoplasm and occasionally in the nuclei. A granulomatous reaction may be present in the upper dermis.

Based on occupational history and the clinical characteristics of the cow's epidemic history, diagnosis is not difficult. If conditions permit, electron microscopy of biopsy specimens or scabs can reveal viral inclusion bodies, further aiding in confirming the diagnosis.

bubble_chart Treatment Measures

If a suspicious sick cow is found, it should be immediately isolated. Milkers should avoid direct contact with the sick cow. Local symptomatic treatment is also important to prevent secondary infections.

bubble_chart Differentiation

Clinically, it needs to be differentiated from molluscum contagiosum and pyogenic granuloma.