Lumpy Skin Disease (LSD)

Lumpy skin disease (LSD) is an infectious viral ailment primarily impacting cattle and water buffalo. It manifests through the formation of nodules on the skin, potentially encompassing the entire body of the animal. LSD frequently presents in epizootic episodes, resulting in notable economic ramifications. Recognizing its severity, the OIE designates LSD as a legally notifiable animal disease. BioVenic, a proficient authority in animal disease diagnosis, is dedicated to assisting clients in developing comprehensive solutions for the diagnosis, treatment, and prevention of LSD.

Etiology

LSD is caused by the lumpy skin disease virus (LSDV), which belongs to the family Poxviridae, subfamily Chordopoxviridae, and genus Capripoxvirus. Various strains of capripoxvirus are responsible for causing the disease, and these strains are antigenically indistinguishable from those causing sheep pox and goat pox, although they are distinct at the genetic level.

LSDV is a double-stranded DNA virus with only 1 serotype. LSDV virions are 260–320 nm in size, with or without envelope, and are brick-shaped or oval. The genome size of LSDV is approximately 151 kbp, encoding 156 putative genes.

Fig. 1 Schematic representation of predicted LSDV structure.¹

Distribution

LSD was historically confined to sub-Saharan Africa, but it has recently spread to other regions, including Egypt, Israel, and Southeast Asia. Outbreaks have been reported in Bangladesh, China, India, Taiwan, Nepal, Vietnam, Bhutan, Hong Kong, Myanmar, Thailand, Malaysia, and Indonesia. The transmission of LSD occurs in various biotypes, ranging from semi-desert to temperate grasslands and irrigated land, indicating the potential for further geographical expansion.

Susceptible Animals

LSD is a host-specific disease. It is susceptible to all breeds of cattle (cattle, dairy cattle, buffalo, etc.). The incidence of buffalo is significantly lower than that of cattle. Usually, cows with high milk production are most severely affected.

Transmission

The main transmission methods of LSD are as follows,

• LSDV spreads over short distances mainly through the bites of blood-sucking insects.
• LSDV-infected animals shed infectious LSDV in saliva, eye, and nasal secretions during viremia. At this time, animals may be infected with LSD by licking each other, ingesting contaminated feed, and drinking water.
• LSDV can also be transmitted vertically to the fetus through the uterus.
• The LSDV can be detected in the semen of LSD-infected bulls, so natural mating or artificial insemination can transmit the disease.
• Intra- or inter-cluster transmission can occur through the sharing of contaminated needles during treatment or immunization.

Fig. 2 Schematic diagram of the transmission modes and spread of LSDV.²

Signs and Symptoms

Once the infection takes hold, affected animals may exhibit an initial fever, which can be quite severe, reaching temperatures that may exceed 41℃. Accompanying the fever are other systemic effects, including anorexia (loss of appetite) and the enlargement of superficial lymph nodes. These early signs serve as important indicators for disease identification and monitoring.

Within 48 hours of the fever onset, characteristic skin nodules start to appear on the animal's body. These nodules measure between 2 to 5 centimeters in diameter and are primarily observed on specific areas such as the head, neck, limbs, udder, genitalia, and perineum. The number of lesions can vary significantly, with mild cases showing a few nodules and severe cases exhibiting multiple nodules covering the entire body.

The distinctive skin lesions serve as the hallmark of LSD. At times, the nodules extend into the subcutaneous layer or penetrate the muscle tissue beneath the dermis and epidermis. Approximately two weeks following the emergence of nodules, a cone-shaped central core of necrotic material may develop within them.

Beyond skin involvement, LSD can also manifest with lesions in the mucous membranes of the mouth and upper respiratory tract. Cases may present with discharge from the eyes and nose, accompanied by additional respiratory symptoms in certain instances.

Fig. 3 Characteristic clinical signs of cattle suffering from LSD.³

Diagnosis

Laboratory diagnosis mainly adopts virus isolation, culture and identification, molecular biology, serology, and other diagnostic testing methods for the diagnosis of LSD.

• Virus Isolation, Culture, and Identification

Bovine skin cells or sheep testis primary cells (LT) can be used for the proliferation and culture of LSDV.

• Molecular Diagnostics

In the detection and diagnosis of LSD, we usually help customers develop diagnostic kits such as PCR, real-time fluorescence qPCR (TaqMan probe method, SYBR Green I dye method), loop-mediated isothermal amplification (LAMP), microarray, etc.

• Immunodiagnostics

Immunological testing is a commonly used method in epidemic monitoring and diagnosis and vaccine immune effect evaluation. We help customers develop highly specific ELISA, virus neutralization, WB, indirect immunofluorescence, agar gel immunodiffusion (AGID) assay kits, etc.

LSD control and eradication in endemic areas depend on accurate, rapid, and efficient diagnosis. BioVenic is committed to developing innovative LSDV diagnostic kits and solutions.

Treatment

Currently, there is no specific treatment protocol for LSD. However, practitioners may implement supportive care measures to enhance the well-being of affected animals. This may include pain management strategies and the judicious use of anti-inflammatory medications to alleviate discomfort and ameliorate the animal's condition throughout the disease. The focus on supportive care aims to enhance the overall comfort and resilience of the animal during the absence of a targeted therapeutic intervention for LSD.

Prevention and Control

• Get Vaccinated in Time
  
  • Vaccination is an essential measure to protect sustainable animals. Attenuated cattle strains and strains derived from sheep and goats have been used as live vaccines against LSDV.
• Strengthen Feeding Management
  
  • It is very necessary to strengthen the feeding of cattle, formulate scientific feeding methods, and perfect the disinfection system.
• Eliminate the Source of LSDV
  
  • LSDV mainly exists in the surrounding environment. Strengthen the timely cleaning of the ground, troughs, and personnel walking areas in the cowshed to improve the growth environment of the cattle and avoid the growth of bacteria.
  • Disinfect and sterilize the environment inside and around the cowshed.
  • In addition, the drinking water and feed of cattle should also be inspected to avoid the presence of pathogens.
• Targeted Treatment
  
  • Taking immediate action upon detecting an afflicted cow is fundamental for effective disease management and maintaining the overall health and productivity of the herd.

BioVenic is dedicated to the advancement of cutting-edge solutions for clients, encompassing diagnostic kits, vaccines, and pharmaceuticals tailored for LSD. Leveraging our extensive expertise in immunology and molecular biology, we adeptly cater to the unique requirements of our clients, expediting their research endeavors. For further information, please do not hesitate to reach out to us.

References

1. Liang, Zhengji, et al. "Understanding the research advances on lumpy skin disease: A comprehensive literature review of experimental evidence." Frontiers in Microbiology 13 (2022): 1065894.
2. Bianchini, Juana, et al. "Lumpy skin disease: a systematic review of mode of transmission, risk of emergence and risk entry pathway." Viruses 15.8 (2023): 1622.
3. Sreedevi, B., et al. "Clinico-molecular diagnosis and characterization of bovine lumpy skin disease virus in Andhra Pradesh, India." Tropical Animal Health and Production 53.4 (2021).