Lumpy Skin Disease (LSD) is a viral infection primarily affecting cattle, causing concern in animal health globally. This disease, characterized by skin nodules, has an impact on livestock populations and the agricultural sector. Understanding its nature, spread, and management is important for those involved in cattle farming and related industries.
What is Lumpy Skin Disease Virus?
LSD is caused by the Lumpy Skin Disease Virus (LSDV), which belongs to the Capripoxvirus genus within the Poxviridae family. This double-stranded DNA virus is closely related to sheeppox and goatpox viruses, though it primarily targets cattle, including both Bos taurus and Bos indicus breeds. Bos taurus breeds, particularly Channel Island breeds, are more susceptible than zebu cattle (Bos indicus).
The virus is resilient in the environment, surviving for at least 35 days in dried scabs. While historically confined to Africa, LSD has spread rapidly through the Middle East, Europe, and Asia since 2012.
How Lumpy Skin Disease Spreads
LSDV primarily spreads through arthropod vectors, such as mosquitoes, biting flies, and ticks, which mechanically transfer the virus between animals. The incidence of LSD infection increases during warmer temperatures when these vectors are more active. While direct contact between infected and uninfected animals is a minor route, the virus can be shed through secretions and excretions.
The virus is detected in nasal and lacrimal secretions, saliva, milk, and semen. Contaminated feed, water, and equipment, such as shared needles, can also contribute to its spread. The movement and trade of infected livestock are primary drivers for long-distance spread.
Recognizing the Symptoms
The most distinctive sign of Lumpy Skin Disease is the appearance of skin nodules, or “lumps.” These firm, raised nodules measure between 1 to 5 centimeters in diameter and can appear anywhere on the body, though they are often found on the head, neck, limbs, udder, scrotum, vulva, and perineum. These lesions can penetrate the full thickness of the skin and sometimes extend to the underlying muscle.
Infected animals develop a high fever (often exceeding 40.5°C), which can persist for about a week. Other common symptoms include enlarged superficial lymph nodes, loss of appetite, and depression. Affected cattle also experience a drop in milk yield, lameness due to limb swelling, and mucopurulent discharge from the eyes and nose. Ulcerative lesions also develop in the mouth and nasal passages, and in severe cases, corneal ulcers can lead to blindness. Secondary bacterial infections are common complications, leading to pneumonia or mastitis.
Managing and Preventing Lumpy Skin Disease
Diagnosis of Lumpy Skin Disease begins with observing characteristic clinical signs, but laboratory confirmation is necessary. Molecular techniques like Polymerase Chain Reaction (PCR) are sensitive for detecting the virus, especially in early stages of infection, using samples from skin lesions, blood, nasal swabs, or milk. Virus isolation and serological tests like ELISA can also be used for confirmation.
There is no specific antiviral treatment for LSD; therefore, management focuses on supportive care for infected animals, including administering antibiotics to address secondary bacterial infections, providing wound care, and ensuring adequate nutrition and pain relief. Prevention focuses on biosecurity measures and vaccination. Strict control of animal movement, quarantine for new animals, and thorough disinfection of premises and equipment help limit spread. Insect control measures are also important due to the vector-borne nature of the disease. Vaccination with live attenuated vaccines is the most effective long-term strategy to reduce disease severity and control outbreaks, requiring high herd coverage (80-100%) for effectiveness.
Impact of Lumpy Skin Disease
Lumpy Skin Disease has significant economic consequences for livestock farmers and national economies. The disease leads to losses through reduced milk production, which can drop by 10% to 85% in affected cows. Weight loss, damage to hides, and reduced fertility or temporary to permanent sterility in bulls also contribute to losses. In severe cases, animal deaths further compound these losses.
Beyond direct production losses, LSD outbreaks can disrupt international trade, as importing countries may impose restrictions or bans on the movement of livestock and livestock products from affected regions. This creates a barrier to global trade and impacts the financial resilience of farmers and agribusinesses. The suffering experienced by affected animals also raises animal welfare concerns.