Bovine Papular Stomatitis (BPS, Proliferative Stomatitis)
Bradford P. Smith
Bovine papular stomatitis (BPS) is a worldwide disease principally of young cattle caused by a parapoxvirus closely related to those of CE and pseudocowpox. BPS, CE, and pseudocowpox have many similarities, and they may represent a single virus adapted to different species.1 There are as many antigenic differences among strains of BPS as among CE and pseudocowpox.1 Local strains therefore are recommended for vaccination.
Infection usually is asymptomatic, and one study of cattle in Virginia demonstrated that 31 of 45 samples from asymptomatic cattle were virus-positive.2 In the same study no asymptomatic deer, goats, or sheep were found to be positive for parapoxvirus, which suggests that cattle are the reservoir host. Lesions consisting of raised papules may be noted on the muzzle, nose, oral mucosa (particularly the hard palate), or esophagus; the differential diagnosis includes Vaccinia virus3 (an Orthopoxvirus found in cattle only in South America), vesicular stomatitis, foot-and-mouth disease (FMD), and bovine viral diarrhea (BVD). In young feedlot cattle, 2- to 10-mm lesions of BPS are common for the first 4 weeks after arrival.4 The rate of morbidity may approach 100%. BPS also occurs as a chronic disease in young cattle.5 It may be the same disease as proliferative stomatitis, muzzle disease, mycotic stomatitis, erosive stomatitis, ulcerative stomatitis, and necrotic stomatitis. In addition to cattle, water buffalo and wild ruminants can be affected.Ulcerative esophagitis caused by BPS virus in a 5-month-old, unthrifty calf was associated with a 20% morbidity rate in a group of 25 calves.6 Outbreaks of severe disease associated with BPS with a mortality rate over 50% have been reported. Weight loss and diarrhea accompanied by papular lesions are commonly associated with the severe syndrome.
Many lesions are erosions or shallow ulcers with elevated borders, whereas others are obvious raised papules. Lesions are found in the mouth, esophagus, and rumen. There are no lesions on the feet. BPS is commonly seen in calves 1 to 12 months of age and is rare in adult cattle, but outbreaks of confirmed BPS in Brazil and Japan involved the teats of dairy cows as well as the hands of milkers.7,8 A confirmed case of severe esophageal lesions in an adult bull that died after 2 months has also been reported.9 The disease is spread by animal contact and appears to be worldwide in distribution.The first evidence of the disease is the appearance of 2- to 4-mm hyperemic foci, most commonly in the ventral margins of the nares. Similar lesions next appear in the mouth. Within 18 hours they become raised papules. Some lesions enlarge to form raised plaques over 1 cm in diameter. Lesions regress in 1 day to 3 weeks, leaving a yellow, red, or brown spot that persists for several weeks more.10 Secondary lesions come and go; some calves are visibly infected for 4 months.10 Most affected animals have no fever or obvious clinical signs, and they continue to eat normally. Leukopenia was not seen in experimentally infected calves.10 Secondary lesions appear to be spread through the blood; intravenous inoculation results in similar upper alimentary tract lesions.11
Histologic lesions consist of hydropic degeneration of the epithelial cells of the oral mucosa, hyperplasia of the papillae of the lamina propria, and eosinophilic inclusions in the cytoplasm of the degenerating epithelial cells. Lesions reaching the ulcerative stage show secondary necrosis, bacterial invasion, and sloughing of epithelium. These are described in detail in the Contagious Ecthyma (Sore Mouth, Orf, Contagious Pustular Dermatitis, Scabby Mouth) section.
BPS has been associated with the “rat tail” syndrome of feedlot cattle.12 Of 84 Texas feedlots, 36 reported the problem, with a morbidity rate of 1% to 10%. The syndrome consists of diarrhea, excessive salivation, poor weight gain, and loss of hair from the end of the tail. Sarcocystosis has also been mentioned in association with “rat tail” syndrome.
BPS is capable of causing painful proliferative lesions in human beings.1 The lesions resemble those caused by CE or pseudocowpox, so they are often described as parapox virus infection. Most often the affected individual has a recent history of examining the mouths of cattle, often with cuts or abrasions on the hands. Lesions in humans apparently are limited to the primary site of inoculation on the hands.
Although ovine ecthyma vaccines are commercially available, no vaccine is marketed for protection against BPS. Local strains of parapoxviruses would be most likely to be more protective than commercial vaccine strains.