Erysipelas polyarthritis is a highly infectious disease which affects sheep and in particular lambs. Many animals including sheep and pigs are able to become infected from this particular disease leading to arthritis. In animals where this joint infection is particularly severe, the prognosis is generally poor.
This form of arthritis is one of the causes of a disease known as joint ill. It may also be called an erysipelas infection or a post dipping lameness. This infectious disease is caused by bacteria called Erysipelothrix rhusiopathiae and the pathogen mainly affects the joints of sheep.
Young lambs are the most susceptible to infection from the disease due to their weak immune systems although sheep of all ages can become infected. The disease is transmitted to the lambs when their umbilicus is exposed to the bacteria which cause erysipelas polyarthritis. Symptoms include the joints being severely damaged and eventually arthritis. The joints become swollen and painful and there may be signs of fever.
Erysipelas arthritis is a zoonotic disease however this is currently quite rare. This means that humans are able to contract the disease if it is transmitted from an infected sheep. Treatment is required for humans as soon as possible due to the adverse health implications which can affect the joints and heart. Vaccinations are available to be administered to sheep. If ewes are vaccinated prior to giving birth, immunity is passed onto their lambs for a short period of time.
Transmission of an erysipelas infection
The Erysipelothrix rhusiopathiae bacteria can be transmitted from exposure to infected material such as contaminated faeces or following dipping, mulesing or lamb marking. Museling is the removal of skin which produces wool in areas where fly strike occurs and lamb marking includes castration, docking tails, and marking the lambís ears. Both of these procedures lead to open wounds and so increase the risk of transmission of the disease.
In some cases, sheep are able to carry contaminated faces on their feet and so can leave it inside the dipping baths. This therefore acts as a source of infection of erysipelas polyarthritis for unaffected animals being dipped. The bacteria enter via an open wound or, in neonatal lambs, through the umbilicus. Wounds include any abrasion of the skin, punctures, and scratches.
Bought in animals can carry the infection in their faeces. Thus, they can then transmit the virus to the farm when they are introduced to a new flock of sheep. The bacteria are relatively hardy and are very resistant. This means that they are able to survive for long periods of time outside of the host and in the environment. Therefore, the risk of infection of joint ill is significantly increased by this fact.
Signs and Symptoms of joint ill
Upon infection from the harmful bacteria, the sheep can initially appear dull and depressed. A fever may also be present in the infected animal. Following this onset of signs and symptoms, the joints of the sheep become adversely affected. The joints, particularly in lambs, become hot or warm to the touch, noticeably more so than the rest of the body. They will become inflamed, swollen, and filled with fluid. Generally, this leads to arthritis or polyarthritis. In some cases, this may even result in a severe form of chronic arthritis which is especially painful. The joints of the infected sheep can usually include the knee, the elbow, and the hock.
Infected sheep usually become lame. The animal will be stiff and reluctant to move. Recovered animals may have lifelong lameness. As a result of these painful signs and symptoms, a loss in production will often follow. Lambs may be lost or even grow less rapidly than their healthy counterparts and a decrease in the amount of wool produced will also be noticed.
Treatment of Polyarthritis
As the disease is caused by a bacterium, certain antibiotic treatments may be used to treat the infected animal. Antibiotics which can be used to destroy the bacteria include ampicillin and penicillin. Despite this, due to resistance to other antibiotics or if another bacteria is responsible for the lameness, a veterinarian needs to be consulted concerning which treatment plan should be used. A diagnosis is often a requirement. Animals with chronic arthritis rarely respond well to treatment.
Prevention of Erysipelas Polyarthritis
As is the general rule of most medicines, prevention can be much more economically worthwhile than having to actually treat any possible infections from the majority of diseases. The main preventative measures for this disease include maintaining good hygiene standards on and around the farm and using vaccines to be inoculated into the sheep.
Concerning these high levels of hygiene, all sheep should be kept in disinfected areas during procedures such as mulesing. Surgical instruments should also be sterilised. The same is true for lamb marking and areas should be disinfected before the beginning of the procedures on different animals. Prior to dipping, sheep should be removed of the faeces on their feet by running them along surfaces such as stones or slats. Lambs can be sprayed with iodine on their umbilicus.
Vaccines are available to reduce the spread of Erysipelas Polyarthritis and vaccinated ewes, before they have given birth, can pass on the necessary maternal antibodies to their lambs. This form of immunity in lambs can last as long as two months. Annual boosters may be given to provide the sheep with long term protection against the disease. Before vaccinating a sheep, needles need to be changed.
Diagnosis of Erysipelas Polyarthritis
Erysipelas Polyarthritis is diagnosed by initially observing the symptoms presented. Following this, the bacteria are isolated for identification. Other bacteria may be the causative factors for the disease of the joints and so samples can be taken from the joints for confirmation. Blood and tissue biopsies may also be used.
Prognosis of joint ill
Animals treated in time can recover rapidly, although occasionally some continue to be lame throughout their lives. Loss in production can occur due to a decrease in growth rate and wool production.