Parapox (=infections with parapoxviruses) is a worldwide spread pox infection of cattle, sheep, goats, camels (new and old world camels) and horses. Parapox infections have zoonotic potential and can also affect humans.

Weltweit

The viral genus parapoxvirus includes viruses found in humans and various mammals, such as cattle, sheep, goats, camels (new and old world camels), and horses.

Infections with parapoxviruses are typical occupational diseases of farmers, hunters and veterinarians. In most cases, small injuries to the skin are sufficient for the virus to penetrate and cause infection. Strict hygienic precautions must be taken for parapox infections in livestock because of the risk of infection to humans. If lesions occur in livestock and subsequently show up in humans, the physician should be informed of the infectious event in the livestock.

In animal-to-animal transmission, viruses enter the animal body through small skin lesions or through the mucous membranes. The viruses multiply at various sites in the body, including the liver. They then cause the local skin lesions typical of parapox infections. The virus is very stable in dry crusts, which can maintain enzootic chains of infection, e.g., in sheep in the field.

Human: 4-8 days; Animal: 3-14 days

In humans, local skin lesions occur sporadically, mostly on the hand. As a rule, parapoxvirus infections are benign and clinical symptoms are limited to the site of infection. Parapoxviruses cause clinical pictures in humans that are indistinguishable from local infections caused by orthopox.

Initial signs of parapox infection in animals are found in the skin in the form of scattered local pustules or small- to large-scale inflammatory skin lesions. The local skin lesions can sometimes expand into extensive cauliflower-like lesions (usually in the mouth area), especially after secondary infections with bacteria. Preferred sites are fur-free areas of the body (e.g., upper and lower lip, eyelid, ears, udder, anus, interdigital cleft).

There is no therapy

Vaccination of animals with an approved live vaccine is not permitted in the EU.

There is no obligation to report parapox. Occasional cases of the disease occur both in humans and in animals. In most cases, the infection of herd animals is only noticed after the appearance of disease symptoms in several animals.

Parapoxviruses are zoonotic pathogens and have already been diagnosed several times in humans in Austria, also in the form of ORF and milking knots (PCP). Parapox infection in humans is not notifiable in Austria.

Parapoxviruses in animals

Parapoxviruses are distributed worldwide. Parapoxviruses include ORF virus (syn. limpet virus, ecthyma contagiosum virus, contagious pustular dermatitis virus) found in sheep, goats, camelids, and humans, Bovine papular stomatitis virus (BPSV) found in cattle, Pseudocowpox virus (PCPV, syn. Udderpox virus, Milker's knot virus, Pseudocowpox virus, Paravaccinia virus), Red deer parapoxvirus (RDPV), and a recently identified equine parapoxvirus. Sheep and goats do not appear to be susceptible to either bovine papular stomatitis virus or pseudocowpox virus. Parapox infections affect every age group of animals. However, adult animals and young animals show differences in disease progression. As a rule, adult animals - in contrast to young animals - do not become severely ill.

The parapoxvirus-like virus of squirrels (= squirrelpox virus, currently assigned to the genus Sciuripoxvirus), the parapoxvirus of seals (Grey seal poxvirus, GSEPV) as well as the Auzduk disease virus, the Camel contagious ecthyma virus and the Chamois contagious ecthyma virus belong to the not clearly identified parapoxviruses.

Parapox infections are not notifiable animal diseases in Austria, but should be treated with caution due to the high infection potential as well as the zoonotic potential (see chapter "Path of infection").

Symptomatology

Humans: Parapoxvirus infection is not life-threatening. However, it should be treated by a physician because of the often painful skin lesions, the usually swollen lymph nodes, the frequently occurring secondary bacterial infection, and the risk of infection. The incubation period for human parapoxvirus infection is 4-8 days. Clinical symptoms of parapoxvirus infection are large nodular local lesions on fingers, hands, or arms (rarely on other parts of the body); the surrounding skin is usually inflamed. The blackish lesions, up to 2 cm in size, are often painful, soon develop a crust, and heal over 3-6 weeks usually with local lymphadenitis without scarring. ORF virus infection of the eyes can lead to permanent blindness in rare cases. In addition, other complications may occur (e.g., urticaria, erythema multiforme bullosum, and bacterial superinfection). Rarely, tumor-like nodules have been reported and may manifest, especially in immunosuppressed patients.

Animal: Lesions of parapox infections, in contrast to notifiable capripoxvirus infection (lumpy skin disease in cattle, sheep and goat pox in sheep and goats), are usually localized to sparsely hairy body regions of ruminants (on the udder, in the nose and mouth region, on the lip region, on the eyelids and ears, and on the interdigital cleft). The skin lesions are initially visible as circumscribed reddened or weeping areas, then develop into vesicles or pustules and later, after about 7 days, they appear as a crust until they heal without scarring after a few weeks in the majority of mild forms. Thereafter, the affected animals are protected from a new infection for several months to years. Depending on the infection pressure and the virulence of the parapox strain, animals that have been infected once can become ill again and again, especially in the case of immunosuppression or after stressful situations.

Lipsgrind (infection with ORF virus):

The spread of lip bark infection in a flock of sheep or goats is from animal to animal, but also indirectly through barn equipment, utensils, dust, and contaminated bedding. The main carriers of the pathogens are usually infected animals with inconspicuous to low-grade symptoms. In many cases of lip scab infections diagnosed by us in Austria, purchased, often asymptomatic farm animals were the causative agents of the disease outbreak. The causative individual animals were not affected by the current events in the new herd due to immunity after overcoming infection in the herd of origin. As with small ruminants, infection in New World camels (llama, alpaca) usually occurs through direct contact with diseased animals. The source of infection can also be farm animals of a different species kept in a mixed herd or wild animals. For New World camels, sheep in particular are considered to be virus reservoirs. They often bring the infection into the herd when kept together. Infected New World camels can also infect sheep or goats. Contact with infected wild animals, especially in high mountain areas, can also cause limpet bark infection in livestock flocks. Since after the lesions have healed, falling crusts can release more viruses into the environment, infection of livestock herds via contaminated pasture cannot be completely ruled out.

In small ruminants, a distinction is made between mild and malignant courses of labial rhinitis, with clinical signs being less pronounced in goats than in sheep. If mother goats suffer from lip scabies, it is very likely that the lambs will become infected due to the close contact, especially since they usually receive too few antibodies with the colostrum and thus too little protection against infection.

In the mild form of the disease (in 20-80% of the animals), the general condition is only insignificantly disturbed. The disease often progresses without an increase in internal body temperature. Small to pea-sized blisters form on the upper and lower lip, in the nasal area and in the interclaw cleft, which gradually crust over. In the genital area, typical changes occur on the underside of the tail, the inner thighs, the labia and the udder. Often, inflammation of the udder occurs as a consequence, which limits the rearing performance of the dam.

In the malignant course (in about 5-20% of animals), cauliflower-like lesions form, often secondary to bacterial infection. The infection spreads to the mucosa of the mouth, tongue, larynx, and esophagus. As a result, the animals are impaired in their food intake and become emaciated. In the genital area and udder, severe inflammation due to secondary bacterial infection is common, as well as deep ulceration and necrosis of the vaginal mucosa. Sometimes, as a result of the activation of the immune defenses, there is also a high-grade increase in internal body temperature of over 40 °C. The animals have a disturbed general condition and die after a few days as a result of refusal to drink and feed.

The clinical signs in New World camels and wild animals are crustose proliferative skin lesions around the lips, in the corners of the mouth, around the eyes, in the area between the toes, and on the udder and teats. The infection is usually accompanied by secondary bacterial infections.

Stomatitis papulosa (infection with bovine papular stomatitis virus, BPSV):

Despite the mild course of the disease in cattle with predominantly strictly localized manifestations, this is not a localized infection but a generalizing one. The pathogen is often transmitted from latently infected dams to calves at birth. The virus can also be transmitted directly from sick or infected asymptomatic young animals to healthy young animals, or it can be ingested indirectly through contaminated feed. Direct infection of adult cattle is difficult.

Stomatitis papulosa is a contagious disease, especially of calves and young animals, characterized by maculo-papular, often ulcerative exanthema of the mucosa on the flot mouth, lips, gingiva and palate. The infection plays a role especially in large farms under stressful situations (e.g., when the animals change environment). Severe forms of progression are rare. Usually only calves and young animals show a pronounced clinical picture.

Udderpox (infection with pseudocowpox virus, PCPV):

Infection is most likely transmitted to cattle mechanically during milking and also by biting stable flies. Pseudocowpox virus infection is a local skin infection that usually affects only the udder or teats of lactating animals. At the peak of infection, the udder or teats are inflamed and painfully swollen. Rarely, udder afflictions occur in non-lactating cows, and very rarely, lesions occur in the mouth.

Equine parapox:

Equine parapox very rarely occurs. The pathogens are transmitted by both direct and indirect contact. Symptoms include: multifocal nodular skin lesions, fever, swelling of the scrotum, apathy, weight loss.

Parapox in wild animals (roe deer, red deer, chamois, ibex):

Parpoxviruses are spread directly as well as indirectly through contaminated feeding sites. Infections are usually discovered after a long severe course. The animals then usually have cauliflower-like lesions in the mouth area.

Therapy

Humans: If lesions appear on fingers or hands, the dermatologist should be consulted without fail. Infections with parapoxviruses usually have a benign and self-limiting course. Therefore, specific treatment is usually not necessary. Contact with other persons should be made with caution - e.g. a handshake with the infected hand should be avoided, if possible, until the healing process is complete. Medical history (information about possible contact with (infected) farm animals or wild animals) is important for the dermatologist with regard to diagnosis. Hygienic measures, such as hand disinfection after visiting the barn, are important preventive measures to avoid infection of humans by infected farm animals. Third parties, with the exception of the veterinarian, children and pets (farmyard dog, cat) should not enter the contaminated barn if farm animals are infected.

Control/prevention in the animal: As a preventive measure, no foreign animals should be immediately introduced into the herd. The introduction of infection into a healthy herd by purchased animals with minor symptoms can be prevented to some extent by careful visual inspection of these animals for skin lesions and voluntary quarantine for 3-4 weeks. Inquiring about possible disease incidence in the herd of origin may also provide clues about past infection. The risk of a hidden virus carrier entering the healthy herd can never be completely ruled out.

If a parapox infection (labial rhinitis, stomatitis papulosa, or udder pox) occurs in a herd, caution should be exercised when handling infected animals, and the wearing of gloves and disinfection of hands are mandatory. Not only can humans become infected, but they can also become carriers of the disease in livestock if hygiene measures are not followed, such as failure to disinfect hands. Entry into the stable should be prohibited to strangers with the exception of the veterinarian. Pets (dogs, cats) should also be prevented from entering, as they can spread the virus-containing dust simply by walking in the barn. Rodent control must be ensured. Since the virus is very resistant to dryness, equipment (shearing machines, tools, etc.), transporters or stall boxes that have been in contact with infected animals should also be disinfected. This can at least reduce the pressure of infection by cleaning and disinfecting with commercially available virus-killing disinfectants. Disinfectants (e.g., 1% NaOH, 2% peracetic acid) should be allowed to act on virus-containing material for at least 4 hours.

A vaccine against parapoxn infections is not available in Austria.

The diagnosis of parapoxvirus infection, as with all smallpox diseases, is made primarily by clinical examination. Virus is detected from a skin biopsy or from the secretion of skin lesions by molecular biology testing procedures; more precise strain determination of the pathogen by sequencing.

Human samples can also be sent in on weekends or late Friday afternoons - they will be stored accordingly by our staff until Monday morning and can be processed in the laboratory as early as Monday morning.

• Skin lesions and/or skin crusts
• Fluids of the skin lesion (native in tubes or on swabs possible - please do not add bacteriological swab transport or other fluids to the sample)

Veterinary Samples:

Specimen type live animals:

• Skin lesions and/or skin crusts
• Fluid of skin lesion (native in tubes or on swab possible - please do not add bacteriological swab transport media or other fluids to sample)

Carcass (dead):

• Skin lesions and/or skin crusts of affected areas.
• Upper digestive tract (tongue lesions, lesions in the pharynx and esophagus) in the malignant form
• Entire animal body or body parts (e.g., head) in livestock and wild animals

Differential Diagnosis Animal:

In small ruminants, differential diagnosis of lamb diphtheroid, sheep and goat pox, plague of small ruminants, foot-and-mouth disease, and Mannheimia haemolytica septicemia must be considered.

In cattle, differential diagnosis should include lumpy skin disease (capripox infection), infection with BHV-2 (syn. pseudo lumpy skin disease), demodicosis, and dermatophilosis, an infection with the bacterium Dermatophilus congolensis, and cutaneous leukemia.