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The crown of the unguis becomes red and painful. Affected animals can limp and ewes may abort.
Farmers and veterinary staff run an increased risk of infection due to direct exposure to aborted infected materials. In humans, the disease is not usually fatal, but if untreated, it can last for many years. A common consequence of prenatal infection by members of this viral genus is the birth of infected offspring that are permanently immunotolerant (BVD-persistent infection (BVD-PI)), which disseminate the virus throughout the herd. BVD-PI animals (i.e., those infected between the second and the fourth months of gestation) carry the virus throughout their lifetime and constantly secrete large numbers of viral particles.
The vector becomes infected when it feeds on an infected animal and then the virus replicates until it reaches the density necessary for transmission to another susceptible animal. Cattle can be a reservoir for verotoxic E.
TSEs cause a slow degeneration of the central nervous system that ultimately leads to the death of an animal, and there is often a significant lapse of time between an animal becoming infected with the disease and displaying the first symptoms. As an example, at the point of infection, cattle may not show clinical symptoms for up to 6 years, and sheep may not show signs for up to 4 years. BCV is an enveloped, single-stranded, positive-sense RNA virus belonging to the Coronaviridae family that causes intestinal and respiratory infections in ruminants worldwide. Infection can cause winter dysentery in adult animals, as well as calf enteritis and enzootic pneumonia complex in calves.
Livestock mortality, treatment costs, abortion, reduced production, discarded milk, and reduced consumer confidence all contribute to the cost of Salmonella to cattle industries. Paratuberculosis in domestic livestock may entail significant economic losses due to several factors, such as reduced production, premature culling, and veterinary costs. In the United States, paratuberculosis is of growing concern to the cattle industry because the presence of the disease impacts international marketing of cattle and cattle products, which causes economic losses to producers.
- The clinical signs that may be seen are abortion, arthritis, respiratory disease, and acute septicemia.
- cattle, as well as in certain wildlife populations.
- In female cattle, typical signs are frequent returns to estrus, prolonged intervals between estrus, prolonged intervals between calving and, rarely, abortions in early pregnancy.
- Leptospirosis can be transmitted transplacentally or venereally, but most often through direct contact with infected milk, urine, or placental fluids.
The bacterium Mycoplasma agalactiae is a common pathogen of small ruminants and is of major importance in veterinary medicine. In ovines this disease is always due to M. agalactiae, but other Mycoplasma species, M. mycoides and M.
When there are signs in cattle, the most common are hyperthermia, abortion towards the end of gestation (in the eighth month), edema (of the udders, teats, vulva, and hocks), and erythema (mucosa, teats, and udders). Seven or eight days after infection, sheep develop acute signs-high temperature, lethargy, and self-isolation from the herd. Shortly after the rise in temperature, the buccal mucosa becomes red and swollen, and large volumes of foamy saliva are produced. The tongue swells up and in some cases turns blue (hence the name of the disease).
Brucellosis is a notifiable disease, and any occurrence of it has to be reported to the local health authority. Depending on the species and the infection rate, different eradication programs are effective. Where incidence rates are high, vaccination programs are necessary to lower the infection rate. Once this has been achieved, surveillance programs linked to slaughter of infected animals are introduced.
TSEs are infectious diseases of the brain that affect animal species in various forms, such as bovine spongiform encephalopathy (BSE, affecting cattle), scrapie (affecting goats and sheep) and chronic wasting disease (CWD, affecting deer). The diseases are caused by altered prion proteins that are resistant to chemicals and heat, and are very difficult to decompose biologically, often surviving in soil for several years. Mycoplasmas-most of which are host-specific-cause chronic diseases that progress slowly in humans and animals.
Transmission generally occurs through contact between infected and susceptible animals. The virus can be excreted into the air during the acute phase of infection. The virus is more-or-less exclusively transmitted by the bite of a small hematophagous dipteran of the genus Culicoides in the Ceratopogonidae family.