Good and welcome rains countrywide may have led to a spate of incidents of lumpy skin disease (LSD) in some areas of Namibia. Farmers are alerted to the outbreak and urged to inform the authorities of any symptoms, according to the weekly newsletter of the Namibian Agricultural Union.

Dr Johannes Shoopala, Acting Chief Veterinary Officer, confirmed that 73 cases of the disease have been recorded in the Otjombinde Constituency in the Epukiro veterinary district in the Omaheke Region.

According to the Animal Health Act 1 of 2011, LSD is classified as a state-controlled disease and any cases must be reported to the nearest state veterinarian.

Lumpy skin disease, which is caused by Neethling strain of the pox virus is caused by biting insects and affect cattle of all breeds and ages.

It usually occurs during wet summer and autumn months, but outbreaks may also occur during a dry season.

Economic losses

Lumpy skin disease can lead to economic losses and export markets as the skins and meat are affected. Usually only up to 20% of cattle on a farm may be affected, but sometimes all the cattle can be infected. Also, mortality rates can range from zero to 40% of a herd. But the effects are not to be taken lightly or ignored.

Sick animals lose weight and abortions may occur. The fertility in cows and bulls is negatively affected.

Also, the animal’s skin is permanently damaged by the pock marks left by the disease and exports of animal-derived products may be impacted. Severely affected animals may need to be culled.

Infection and spread

The disease, which may be severe or mild. occurs sporadically, but in some years, it spreads quickly and turns into an epidemic. Once the cattle are infected by the insect vector, the virus is transmitted between susceptible cattle through direct contact through the saliva through drinking and feeding troughs and through contact with the inflamed skin lesions.

Some affected animals may show no clinical signs but still spread the virus through their saliva.  The disease can also be transmitted via milk to suckling calves.

The disease is spread along paths or roads along which infected animals were moved. It is also possible that sheep may be carriers, although they don’t show symptoms.

Symptoms

Symptoms develop as the disease evolve. The incubation after infection is about seven days. Then follows a two-phased fever response that lasts for four to fourteen days.

  • During this time, the animal may discharge mucous from the nose, severe salivation and a reduced appetite. The eyes become inflamed and may discharge.
  • Just before or during the second phase of the fever, telltale lumps of 5 – 10 mm in diameter appear. These lumps may be just a few or hundreds spread all over the animal’s body. These lumps are deep and affect the skin, the underlying tissue and sometimes also the underlying muscle.
  • When the animal recovers, the lumps may clear up quickly and harden, but the hard lumps may remain visible on the skin for a couple of months
  • Sometimes the lumps shed early and form raw, pus-filled sores or ulcers and abscesses.
  • Soft, yellowish-grey ulcers may also appear on the mucous membranes of the mouth, nose, respiratory tract, rumen, and genital organs.
  • Internal swelling on the limbs may occur and can cause lameness or paralysis of the limb.
  • Pneumonia may develop due as a result of secondary infections, and for weeks and months after the disease, the windpipe may narrow, causing the animals to have difficulty breathing.

Prevention and control

As insects play the main role in transmitting the disease, it is important to dip the cattle with an insect repellent. Since insects cannot be quarantined, prevention through quarantine measures and restrictions on animal movement is not really effective, but infected animals should be isolated and not use the same feeding and water troughs as healthy animals.

Vaccination

Effective prevention and control through regular and early annual vaccination of animals is the best way to prevent animals from becoming infected.

Preventative vaccination of animals is crucial for controlling lumpy skin disease, especially following the increase in lumpy skin disease in recent years.

  • Vaccinate all animals older than six months annually during spring;
  • It is safe to vaccinate pregnant cows;
  • Vaccinating animals during an outbreak can spread the disease if the same needle is used for more than one animal;
  • Calves younger than six months, of susceptible, unvaccinated cows have not acquired protective colostrum immunity and must be vaccinated as soon as lumpy skin disease is a problem in the area;
  • Immunity in vaccinated animals starts to develop about ten days after vaccination and is complete after three weeks;
  • Ensure the vaccine is not exposed to light as ultraviolet rays will deactivate it;
  • Generally, good immunity is obtained by vaccination.

It is important to note that although some cattle have natural resistance to the disease, they do not develop antibodies after vaccination. It appears their calves do not develop colostrum immunity and are susceptible. Also, infected bulls’ semen is also contaminated with the virus.

Treatment

All incidences of lumpy skin disease must be reported to the nearest state veterinarian. Provide symptomatic treatment and good care to keep the animals as comfortable as possible and give antibiotics to prevent secondary infections.

Source reference

NAU Newsletter 24 January 2025

https://mail.google.com/mail/u/0/#inbox/FMfcgzQZSsCxSlnKfqqsXglwZcbDDGzp