Border disease (BD)

Border disease (BD) is caused by the Pestivirus border disease virus (BDV). BD is a viral disease of sheep and goats first reported in sheep in 1959 from the border region of England and Wales, and since recorded worldwide.

Prevalence rates in sheep vary from 5% to 50% between countries and from region to region within countries. Vertical transmission plays an important role in the epidemiology of the disease. Infection of fetuses can result in the birth of persistently infected (PI) lambs. These PI lambs are viraemic, antibody negative, and constantly excrete virus. The virus spreads from sheep to sheep, with PI animals being the most potent source of infection.

Brucellosis

Brucellosis is an infectious disease caused by Brucella bacteria. Brucella species of major concern are B. abortus, primarily affecting cattle; B. melitensis, primarily affecting sheep and goats; and B. suis, primarily affecting pigs. All these Brucella species are non–host-specific and may be transmitted to other animal species or humans under appropriate conditions.

Brucellosis is commonly transmitted to susceptible animals by direct contact with infected animals or in an environment that has been contaminated with discharges from infected animals. Brucellosis is thus a herd or flock problem.

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. These programs lead to “Brucellosis-Free” and “Officially Brucellosis-Free” status for specified regions or whole countries. In Europe, surveillance is regulated in the EU directive 2003/99/EC on Monitoring of Zoonoses.

Caprine arthritis encephalitis (CAE)

CAE and maedi-visna are persistent viral infections caused by closely related lentiviruses belonging to the Retroviridae family. Although there are only a few documented cases of interspecific transmission, CAEV can infect sheep and maedi-visna can infect goats.

The infection is transmitted very early to the lamb or kid via the dam in colostrum or milk, or via the respiratory secretions of infected animals. Now a permanent carrier, the lamb or kid can transmit the virus to the rest of the flock throughout its life.

Chlamydiosis

In ruminants, chlamydiosis is a contagious disease caused by a bacterium that also infects birds and humans. It can cause abortion, premature delivery, pneumonia, conjunctivitis, and arthritis in ruminants. The infection can be transmitted to the newborn, young, or adult ruminant by the large numbers of bacteria excreted in fetal envelopes and fluids, feces, urine, and milk, although the main route of infection is via the inhalation of contaminated aerosols. Chlamydia taxonomy was revised by Everett in 1999. In the new classification, the species are divided between two main genera:

Foot and mouth disease (FMD)

Foot and mouth disease (FMD) is a highly contagious disease that affects all cloven-hoofed animals, and is widespread throughout the world. FMD cannot be differentiated clinically from other vesicular diseases such as swine vesicular disease (SVD).

The virus is a member of the genus Apthovirus and the family Picornaviridae. There are seven serotypes of FMD virus: O, A, C, SAT 1, SAT 2, SAT 3, and Asia 1. Infection with any one serotype does not confer immunity against one of the other serotypes.

Maedi-visna

Maedi-visna (MV), ovine progressive pneumonia (OPP), and caprine arthritis-encephalitis (CAE) are chronic diseases of sheep and goats that are typically grouped together as small ruminant lentiviruses (SRLVs). Maedi-visna is an Icelandic name that describes two of the syndromes associated with the MV virus. “Maedi” translates to “labored breathing” and refers to the interstitial pneumonitis aspect of the disease; and “visna” translates to “wasting”, which is a sign associated with paralyzing meningoencephalitis.

Ovine lentiviruses have been identified in sheep-rearing countries throughout the world, with the exception of New Zealand and Australia, and CAEV is primarily found within industrialized countries, coinciding with the international transport of dairy goats (European breeds).

Neonatal gastroenteritis

Diarrhea is a major cause of death in calves and other young ruminants. This form of neonatal gastroenteritis is caused by ingested microorganisms that reach the gut. Many different microorganisms can cause neonatal diarrhea, including viruses (rotavirus, coronavirus), bacteria (Salmonella, enterotoxinogenic Escherichia coli K99), and protozoa (Cryptosporidium parvum, coccidia).

Paratuberculosis /Johne’s disease (MAP)

Paratuberculosis, also known as Johne ’s disease, is caused by the presence of the Myobacterium avium subspecies paratuberculosis in the small intestine of ruminants. It is a worldwide animal health problem, especially affecting beef and dairy herds.

Paratuberculosis is a chronic debilitating enteritis, and its presence in an animal herd can have serious effects on production.

Q fever

Q (Query) fever is an ubiquitous zoonosis that is found throughout the world (apart from New Zealand). It is caused by Coxiella burnetii, an obligate intracellular bacterium that can infect many different animal species, including ruminants, dogs, cats, birds, and arthropods as well as humans. In ruminants (which are believed to be the main reservoir for human infection), the disease is mainly associated with reproductive dysfunction. It usually remains asymptomatic and is not usually screened for unless an animal has aborted several times or shows reproductive problems. Coxiella burnetii colonizes the placenta and causes premature delivery, low birth weight, and abortion.

Toxoplasmosis

Toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii, which belongs to the family of the Sarcocystiidae. Toxoplasma infections are widespread in humans and many other species of warm-blooded animals, including pigs, sheep, and goats. Occurrence is worldwide; however, the prevalence in human and animal populations varies greatly among countries.