Contagious ecthyma B08.0

Notifiable, harmless, local infectious disease induced by contact infection with parapoxviruses (Orfvirus that affects sheep and goats) from the Poxviridae family, zooanthroponosis, with formation of inflammatory nodules at the site of infection.

Parapoxvirus (3 species):

• P. bovis 1 (in cattle, pathogen causing stomatitis papulosa)
• P. bovis 2 (in cattle: pathogen causing udder pox; in humans: milking knots)
• P. ovis, formerly known as Orf virus (in sheep, goats and chamois, pathogen of Ecthyma contagiosum).

Local infection through direct contact with the diseased animals.

The Orf virus is distributed worldwide. The occurrence of Orf infection in humans is rare. It is usually linked to specific occupational groups (farmers, sheep breeders, veterinarians). Incidental infections also occur in contact with infected animals (viral lesions on teats and mouths of calves/cows/sheep). An expansion of infected host animals is observed in recent years (cats,reindeer, camels). In rare cases, human-to-human transmission has occurred (Caravaglio JV et al. 2017).

Incubation period: 3-10 days. Thereafter appearance of very characteristic skin symptoms:

• 1st week (maculopapular stage): Single or multiple, coarse, elevated, 0.5-1.5 cm large, blue-reddish papules or nodules. Regional lymphangitis and lymphadenitis possible.
• 2nd week (cockade stage): Central redness, surrounding white ring, peripheral, inflammatory reddened yard.
• 3rd week (serous exudation): Weeping surface.
• 4th week: Dry papule covered with a yellow-black crust.
• 5th week: Papillomatous transformation of the surface.
• From the 6th week: regression of the papule, rejection of the crust. Always scarless healing.
• Orf-induced erythema exsudativum multiforme is rare.

Virus antigen detection from efflorescence material, antibody titer determination in serum (ELISA), recall antigen testing with parapoxvirus bovis 2-antigen, electron-optical virus detection ( negative staining).

Milking knots: Analogous clinical symptomatology. Differentiation by anamnesis. Which animal contact was present?

Anthrax of the skin: very rare; rapid formation of an inflammatory nodule or pustule; rapid spread, haemorrhagic bladder; early onset of tiredness, malaise, headache with varying degrees of fever.

Granuloma teleangiectaticum: usually only solitary; histology is diagnostic

Chronic papillomatous pyoderma: purulent, painful, pathogen detection

Sporotrichosis: lymphogenically transmitted infection, multiple, less symptomatic, bluish-red nodes arranged in chains along the lymphatic pathways.

Bacterial superinfections. Rarely is the Orf-induced erythema exsudativum multiforme.

The clinical appearance of Ecthma contagiosum (Orf) is identical to that of the milking knot (transmitted by cows), so a distinction is not necessary.

Anamneses/findings: A 43 year old Turkish patient returned to Germany after a 4 week holiday in her Turkish home village. 2 weeks later she developed purulent nodules with an inflammatory yard on the right palm and the index finger.

Questioning revealed that she had taken part in a domestic slaughter of a sheep 14 days earlier. She had suffered slight cuts in these areas. A few days later his blisters appeared at the cuts. She also noticed a slight fever and painful lymphadenitis in her armpit.

Laboratory: BSG 30/50; CRP: 22,4mg/l (norm<5); low neutrophil leucocytosis (11.500/ml); detection of AK against parapoxviruses;

therapy: antiseptic local therapy; furthermore ciprofloxacin for 7 days because of a bacterial overlay.

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