Erysipeloid infection in a sheep farmer with coexisting orf

Erysipeloid is a rarely reported zoonotic infection caused by Erysipelothrix rhusiopathiae. We report a case of coexisting erysipeloid and orf infections in a sheep farmer, an association not previously recorded to our knowledge.

Parapox infection in a gazelle kid (Gazella gazella)

A captured gazelle kid (Gazella gazella) held in a mixed herd of sheep and goats in Israel developed the characteristic lesions of contagious ecthyma. Clinical diagnosis was confirmed by electron microscopy and histopathology examinations of infected tissue.

Severe complications induced by experimental bacterial superinfection of orf lesions

Twelve goats about 3 months of age were divided into 4 equal groups. Goats in Groups 1 and 2 were infected with orf virus followed by Corynebacterium pyogenes infection of Groups 1 and 3, 3 days after the first appearance of orf lesions. Goats in Group 4 were uninfected controls. Complicated orf lesions which consisted of wet suppurative scabs around the entire lips were observed in goats in Group 1. The lesions persisted for 24 days but were most severe from days 8 to 13. Goats in Group 2 developed lesions typical of orf virus infection that lasted 10 days, while goats in Group 3 developed small nodules of about 1 cm diameter, 48 hours following the introduction of C. pyogenes, which persisted for only 6 days. No lesion was observed in goats in Group 4. Two goats in Group 1 with complicated orf died after 16 and 22 days respectively.

Vaccination of sheep with cell culture grown orf virus

Orf virus, derived from contagious pustular dermatitis (scabby mouth) lesions in sheep, was adapted to cell culture and subsequently evaluated as a potential vaccine for sheep. The traditional vaccine virus, prepared from the infected scabs of orf virus lesions in sheep, was used to vaccinate sheep by scratching with an applicator (mounted pins) dipped in virus. Less than 10 TCID50 (50% tissue culture infectious doses) of virus was required to produce large lesions (greater than 5 mm diameter) which developed during a period of 10 to 14 d prior to onset of healing which was complete by 28 to 30 d. A serum neutralising antibody response was also detected and protection against challenge by application of virulent virus to abraded skin was demonstrated in that challenge lesions developed and healed more quickly (14 d against 30 d). However, cell culture-adapted virus required more than 10(5) TCID50 to induce even small lesions (less than 2 mm diameter). An antibody response could not be detected and no evidence of protection against challenge with virulent virus was demonstrated. In contrast, a recent field isolate has yielded a cell culture-adapted virus preparation that readily infects sheep, produces large lesions, detectable antibody and protects against challenge. This isolate is distinct from the traditional vaccine strain on the basis of restriction enzyme analysis but provides cross-protection in sheep inmmunisation and challenge studies. These results demonstrate that a cell culture produced scabby mouth vaccine is feasible.

In vivo and in vitro characteristics of contagious ecthyma virus isolates: host response mechanism

Three Vero cell culture-adapted contagious ecthyma virus (CEV) isolates were compared by plaque morphology, ability to induce vesicles in skin and in vivo growth curve characteristics by sampling sequentially experimental skin lesions produced in four sheep and one goat. Two of the isolates (CEV-29A and CEV-378) were from outbreaks of ecthyma in sheep and one (CEV-102) from a human case of orf. When replicating in Vero cells, the viruses exhibited similar growth parameters, but were distinguishable from each other on the basis of plaque morphology. In vivo latent periods for these isolates were 48 h (CEV-29A), 96 h (CEV-102), and 120 h (CEV-378). When isolates CEV-102 and CEV-29A were passaged into another sheep, they produced similar patterns of growth. Isolate CEV-102 produced the highest infectivity titer [1.4 X 10(9) plaque forming units (PFU) g-1], followed by CEV-29A (6.8 X 10(7) PFU g-1) and CEV-378 (2.5 X 10(7) PFU g-1). In addition, these viruses varied in their ability to induce vesicle formation. Virus was no longer detectable at the inoculation sites at 288 h post-infection (PI). We conclude that plaque morphology, ability to induce vesicle formation in the skin and growth curves in the skin can be considered as important criteria to differentiate CEV isolates. A comparison of the growth curves of CEV-378 in the skin of sheep and goats suggested differences in virus-host interaction between the two animal species. Since intravenous injection of 1 X 10(9) PFU of CEV failed to produce lesions in the sham-scarified skin of sheep, virus spread via the hematogenous route from one site to another appears unlikely. No virus-neutralizing antibody or interferons were found in serum samples or in skin homogenates collected between 0 and 24 days PI. Virus-neutralizing antibody was present in the circulation as late as 24 days PI. Lymphocytes collected from CEV-exposed sheep as early as 12 days PI responded specifically to stimulation with CEV antigen. As this was about the time when infectious virus disappeared from the sites, we assume that cell-associated immune mechanisms may play a larger role in virus clearance from skin lesions than virus-neutralizing antibody.

Studies of the pathogenesis of orf virus infection in sheep

Damage to the skin is essential for the establishment of orf virus infection and the development of typical lesions. However, analysis of the pathogenesis of experimental lesions induced by viral challenge of mildly abraded skin, indicated that the virus does not establish in the damaged epidermis, but replicates in the cells of an underlying replacement epidermal layer derived from the walls of the wool follicles. The skin reaction consists of a cellular response with necrosis and sloughing of the affected epidermis and underlying stratum papillare of the dermis. Healing is then completed by the formation of a third epidermis derived from the deeper portions of the wool follicles. Previous cutaneous infection did not prevent reintroduction of the disease, even on the same area of skin although the lesions were less severe and persisted for a shorter period.

Attempted reactivation of contagious ecthyma in Dall sheep

Dexamethasone was administered to 2 Dall ewes that had clinically recovered from contagious ecthyma in an attempt to reactivate contagious ecthyma in the sheep. Clinical signs of disease were not detected within 24 days after corticosteroid injection, and virus was not detected in tissues collected at necropsy.

Orf. A case report with histologic, electron microscopic, and immunoperoxidase studies

Orf is an occupational skin disease acquired through contact with infected animals. In humans, orf is usually a self-limited disease that resolves spontaneously within four to 24 weeks. We report a case with multiple lesions of orf, acquired by contact with a wild sheep. The patient was temporarily immunosuppressed by a concomitant viral hepatitis. We reviewed the histologic and electron microscopic findings. Also, we attempted to stain the Parapoxvirus in the skin of the patient, using the immunoperoxidase technique. The antiserum was obtained from sheep immunized against orf. We used lesional skin from sheep infected with orf as a positive control. The negative results of this technique in the patient's skin indicated that Parapoxvirus infecting wild sheep is antigenically different from that causing the disease in domestic animals.

The genome of orf virus: restriction endonuclease analysis of viral DNA isolated from lesions of orf in sheep

The purification of orf virus directly from scab material from clinical cases of orf in sheep and restriction endonuclease analysis of the viral DNA is described. Between 7 x 10(9) and 1.6 x 10(11) virus particles, and 0.7 to 22.8 micrograms of viral DNA could be recovered from 1g of scab material. Considerable heterogeneity was observed between different field isolates when restriction endonuclease digests of orf DNA were compared by gel electrophoresis. It was also shown, for two isolates, that these fragment patterns did not change after plaque purification and passage in cell culture. It is suggested that restriction endonuclease analysis of viral DNA offers a convenient method of identification of isolates of orf virus. The molecular weight of orf DNA was determined and found to be 88.8 x 10(6).

Nuclear changes in cells infected with parapoxviruses stomatitis papulosa and orf: an in vivo and in vitro ultrastructural study

During ultrahistological investigations of naturally occurring cases of stomatitis papulosa in cattle and Orf in sheep, nuclear changes consisting of aggregations of double membrane-containing tubular structures (outer diam. 100 to 130 nm, inner diam. 50 to 65 nm) and filamentous material were observed. These changes could be reproduced in vitro after infection of bovine (BEL) and ovine (OEL) embryonic lung cell cultures with stomatitis papulosa virus and Orf virus isolates. Nuclear tubules were mostly associated with stomatitis papulosa, whereas filaments were regularly detected in Orf virus infections in vivo. Stomatitis papulosa virus also induced nuclear tubules in vitro in the two cell culture types employed, whereas tubular structures after Orf virus infection only developed in ovine embryonic lung cell cultures in addition to filamentous structures. Orf virus infection of BEL cell cultures induced the formation of filaments. Fluorescent antibody staining revealed parapoxvirus-specific antigens only in the cytoplasm of infected cells.

ORF in sheep and goats in Nigeria

Orf virus was demonstrated in biopsy material taken from lambs during an outbreak of the disease on the University of Ibadan Teaching and Research Farm. Clinical cases were also seen in goats. The confirmation of orf in Nigeria is discussed in relation to peste des petits ruminants, an important virus disease of small ruminants in West African countries.

Serologic and cross-immunity studies with contagious ecthyma and goat pox virus isolates from the western United States

Contagious ecthyma and goat pox viruses were isolated from goats affected with papulopustular epidermal lesions. Results of in vitro serum neutralization and in vivo cross-immunity studies indicate that these contagious ecthyma and goat pox isolates from the western United States are antigenically dissimilar and that exposure or vaccination with one isolate could not be used as a method of inducing immunity to the other. Exposure to each isolate conferred immunity to re-exposure with the same agent. The serum neutralization test indicates that the severity and persistance of lesions to goat pox infection influences the nature of the antibody response to an initial exposure.

[Robert Koch's unpublished and unfinished experiments on sheep-pox (author's transl)]

The archives of the Robert Koch Institute include a casket with preparations and handwritten notes by Robert Koch (Fig. 1). He made these preparations during his time as a rural doctor between October of 1878 and September of 1880. They refer to an outbreak of sheep-pox at Rackwitz, a place near his practice at Wollstein (Fig. 2). This work has not been published; we know of it from one of Robert Koch's private letters (11). To reconstruct his working scheme and reasoning, we consulted particularly his reports on rinderpest experiments which he began in 1896 (6). The preparations from this casket which had been stained with Bismarck brown (according to Weigert) date back to a period when Robert Koch developed the foundations of bacteriology and they are evidence of his preparedness to accept new operational procedures (1, 2, 3). Thus, we have to assume that these preparations were to serve as evidence of a bacteriological etiology of sheep-pox. A wrong conclusion as to associations between the superinfection present and etiology of the disease (7) was ruled out by maintaining his own postulate. Simultaneously with this preparation work, Robert Koch performed animal experiments (11). His experience from these studies was utilized later on in his rinderpest experiments (6). On account of his confrontation with viral disease - which had its starting point in his unpublished work on sheep-pox - Robert Koch stated his postulate to be valid in the same manner as if bacteriological etiology had been demonstrated (4,6). The importance of these preparations is also seen in the interpretation of viral tissue damage, i.e. increase of macrophages and plasma cells with subsequent necrosis (9) characteristic of vira infection (Figs. 3, 4).

Viral diseases of the skin, 1975: a 25-year perspective

Most of the major advances in modern virology during the past 25 years have been due principally to the development of refined laboratory techniques and tools and have provided a fund of new knowledge and information about the nature of viral infection and pathogenesis. One group of viruses of interest to dermatologists, the herpesviruses, is undergoing intensive biochemical investigation to determine whether it is carcinogenic. As a result of the success of the World Health Organization's campaign to eradicate smallpox, it is predicted that by the end of 1976, smallpox will have been eradicated. Other viruses of dermatologic interest which are now being studied include the agents of warts, molluscum contagiosum, cat-scratch disease, and enteroviruses. Current research in the field of viral chemotherapy may provide the basis for successfully treating these diseases in the future.

Human orf

Human orf is usually considered a rare disease caused by a virus belonging to the paravaccinia subgroup of pox viruses and transmitted to man from sheep and goats. This paper presents 119 new human cases with epidemiological, clinical, histopathological and ultrastructural findings. Erythema multiforme was found to be a common complication of human orf. Other complications tended to be caused by overtreatment. Electron microscopy of negatively stained suspensions from lesions was found to be the best and most rapid diagnostic method available.