Bovine papillomavirus (BPV) is a common viral disease primarily affecting cattle globally. This DNA virus causes growths or tumors (papillomas or fibropapillomas) on the skin and internal organs. BPV is widespread, with high incidence in regions with dense ruminant populations, including the UK, Germany, Japan, India, the USA, and Brazil.
Forms of Bovine Papillomavirus Infection
Bovine papillomavirus manifests in several distinct clinical forms, each associated with specific BPV types and lesion characteristics.
Cutaneous warts (papillomas) are common, appearing as cauliflower-like, flat, or fibrous growths. They are often found on the head, neck, udder, teats, and genital areas, and frequently resolve on their own, especially in younger animals. Various BPV types, particularly 1 and 2, are linked to these skin lesions, with types 1 and 2 often causing fibropapillomas that lead to nodular appearances.
Bovine cutaneous sarcoids are locally invasive tumors that do not spread. They are often associated with BPV-1 and BPV-2 in cattle. Unlike benign warts, sarcoids tend to persist, posing a more challenging clinical problem.
Alimentary tract papillomas are primarily caused by BPV-4, leading to warts in the esophagus, rumen, and bladder. While these lesions can cause issues like feeding and breathing difficulties, they can also progress to more serious conditions, such as bladder cancer, especially when cattle simultaneously consume bracken fern, which acts as a co-carcinogen.
How Bovine Papillomavirus Spreads
The transmission of BPV primarily occurs through direct contact between infected and uninfected cattle, often involving skin-to-skin contact where abrasions or minor injuries allow viral entry. Warts contain large amounts of the infectious virus, which is relatively stable in the environment.
Indirect contact also plays a substantial role. Contaminated equipment (fomites) can readily spread the virus. Items like halters, clippers, milking machines, tattooing instruments, ear taggers, and dehorners, if not properly disinfected, can serve as vectors. The virus can survive on these surfaces for weeks or months, especially if protected by tissue remnants.
The virus can persist in the environment, meaning areas where infected animals have been (e.g., fence posts or stalls) can remain a source of infection, contributing to its spread. While less common than direct or indirect contact, insects like face flies may also mechanically transmit BPV.
Managing Bovine Papillomavirus
Diagnosis typically relies on the warts’ characteristic appearance (cauliflower-like, flat, or fibrous forms) and common locations, allowing for a presumptive diagnosis. For confirmation or BPV type identification, laboratory tests like Polymerase Chain Reaction (PCR) or histopathology can be used, though not always necessary for routine cases.
Many BPV-induced warts, especially in younger animals, regress spontaneously, sometimes within a year. If persistent, interfering with functions like milking, or problematic, treatment options include surgical removal, cryotherapy (freezing), or autogenous vaccines. Autogenous vaccines, prepared from the animal’s own warts, aim to stimulate an immune response, though efficacy varies.
No specific antiviral medication exists for BPV. Persistent bovine cutaneous sarcoids are challenging to treat, potentially involving surgical excision, cryotherapy, chemotherapy, or radiation, with varied success. Isolating affected animals helps limit herd spread.
Protecting Herds from Bovine Papillomavirus
Preventive measures control BPV spread within herds. Strict biosecurity protocols are a primary defense, involving thorough disinfection of equipment like clippers, tattooing instruments, and dehorners between animals to prevent viral transfer. A 2% to 4% formaldehyde solution can be used, with instruments rinsed before use.
Quarantining new animals before herd introduction prevents virus entry. Maintaining good hygiene in housing areas reduces environmental viral load. Regular cleaning and disinfection of stalls, feeders, and water dispensers minimizes contamination.
Vaccination protects herds from BPV. Both commercial and autogenous vaccines are available. Commercial vaccines are often type-specific, targeting common BPV types to prevent or reduce outbreak severity in uninfected cattle. Autogenous vaccines, made from warts collected within a specific herd, are tailored to local viral strains. Reducing skin abrasions (e.g., from rough surfaces or sharp objects) also prevents viral entry.
Bovine Papillomavirus and Human Health
Bovine papillomavirus is non-zoonotic, meaning it does not infect humans or cause disease. Papillomaviruses are highly species-specific; BPV types infecting cattle are distinct from human papillomavirus (HPV) types. While BPV models HPV research, this does not imply cross-species infection.
Contact with infected cattle or consuming beef products poses no direct BPV infection risk to humans. However, always follow standard hygiene practices, such as washing hands thoroughly after handling livestock.