Lumpy skin disease (LSD) is a viral cattle disease caused by the Neethling strain LSD virus (LSDV), belonging to the genus Capri poxvirus family Poxviridae.
Lumpy skin disease (LSD) is a viral cattle disease caused by the Neethling strain LSD virus (LSDV), belonging to the genus Capri poxvirus family Poxviridae. All Capri poxviruses have a double-stranded DNA genome of approximately 150 bp to 151 kbp long.
The LSD virus is one of the most important threats to beef and dairy farming in Africa and the Middle East due to skin destruction, reduced milk production, abortions, low weight gain, and secondary bacterial infections. Fever is caused by skin pustules that cover the entire animal’s body.
Emaciation (loss of body condition because of unwillingness to eat); temporary or permanent loss of milk production; lowered or complete loss of fertility in bulls and cows; abortion; as well as permanent damage to hides (skin).
Transmission occurs through direct contact between infected and non-infected animals; mechanical and biological transmission by Aedes aegypti mosquitoes, Culicoides, and hard Ixodid ticks that are associated with wet, warm summer seasons has been reported.
Sources of the virus:
- The virus is present in high amounts in skin nodules, scabs, and crusts.
- Also present in blood, semen, saliva, ocular, and nasal discharge.
- In semen, it may be present for up to 42 days post-infection.
Pathogenesis:
Lumpy skin disease (LSD) is a viral disease transmitted through parasites, generally blood sucking like flies and ticks, that enter the host through mucous membranes or wounds in the skin. Once the virus gains entry into the host, it initially replicates at the entry site, effects lymphoid and epithelial cells of the host, and forms characteristic nodules just under the skin. After invading lymph nodes, viruses enter the bloodstream, causing viremia.
The virus generally invades the lymph nodes, mucous membrane, and skin of the host and results in symptoms like fever, skin lesions, nodules under the skin, etc. The nodules under the skin were found to be high in virus concentration, and these findings made the disease highly contagious. Transmission may occur through direct contact or through mechanical vectors like parasites.
In addition to lymph nodes, LSD also affects internal organs like the liver, spleen, and kidneys through the blood stream. In the case of liver hepatitis, liver dysfunction is a common finding.
The severity of the internal organ affected depends on the immune response of the host and other factors. Various organs affected lead to a variety of signs and symptoms, including generalised lesions, jaundice, and, in the most severe cases, death.
Cattle that recover from the disease develop immunity against its subsequent attacks, but the virus may persist in recovered animals at low levels.
Epidemiology:
The morbidity and mortality rates vary between 10 and 20%. And 1 to 5%, respectively.
Diagnosis:
To diagnose LSD virus, we first take a blood, semen, or tissue sample. Then do histopathology and virus isolation. In virus isolation, we use Madin-Darby bovine kidney cells to isolate the virus and check for 7 days regularly for any cytopathic effect.
Then we use conventional PCR to diagnose the Capri poxvirus. Primer sets are designed from the VP32 gene of the viral attachment protein gene. We use the forward primer, 5′-TTTCCTGATTTTTCTTACTAT-3′, and the reverse primer, 5′-AAATTATATA C GTAAATAAC-3′, designed by Binepal and Ireland.
Total reaction volumes are 25 µl, which contain 0.2 µl of each forward and reverse primer at a final concentration of 20 pmol of each primer. 12.5 µl master mix, 2.5 µl DNA template (contains 200 ng). nuclease-free, sterile, double-distilled water, 25 µl.
Negative and positive controls were included for each reaction. The amplification conditions are an initial denaturation cycle at 95°C for 2 min, 40 cycles (denaturation at 95°C for 30 s, annealing at 55°C for 30 s, and extension at 72°C for 1 min), followed by a final extension cycle at 72°C for 10 min. Amplicons (5 µl) were separated on a 1% agarose gel at 100 V for 30 min, according to the methods described by Ireland and Binepal [30].
The specific primers set amplified a DNA fragment of 192 bp, equal to the expected amplification product size from LSDV. Why is this so? This specification only amplifies the DNA of LSDV. The DNA ladder with 100 base pairs was used.
Vaccination:
Lumpy skin disease in Pakistan was first reported in Sindh province and later spread in Punjab province too. In Sindh, more than 570 cows were reported dead from this disease.
Farmers raising livestock on a small scale to fulfil their milk and meat requirements are the most affected. As our country is a developing country and is not economically strong enough to support the farmers with free vaccines, some of them are buying vaccines on their own, costing 44,000 for a 100-ml bottle.
Cattle’s health remains uncertain as the vaccine shows effect after 28 days of inoculation. Some health experts said that by consuming the milk of the cattle, the disease would not be transmitted, but a local survey by Dawn newspaper in Karachi estimated that milk consumption had reduced to 60–70 percent in the city of Karachi due to LSD.
There has been no treatment for the lumpy skin disease virus until now. Vaccines are available, but there are no proper LSD virus vaccines as of today. LSD, but we can use cross-vaccinated, live-attenuated GPPV and SPPV. Animal skin can be treated with non-steroidal anti-inflammatory drugs (NSAIDs).
Treatment is nonspecific, like using anti-inflammatory drugs, antibiotics, and vitamin injections. Oxytetracycline was effective as it had antiprotozoal properties as well, but when there were severe wounds, the penicillin group was effective.
Natural Treatment:
We also used natural things to overcome its severity. Betel leaves weigh 10 grams. Chilli 10 gms. Salt: 10 grams. Mix jaggery and make a paste, and give it to animals three times a day. Betel stops inflammation, and jaggery helps animals eat.
Control and Prevention:
Mass vaccination:
It means vaccination should be done at every level, even for small farmers.
Farmer awareness:
It is the keen responsibility of farmers to stop the prevalence of LSDV. A well-aware society will guarantee public health by supporting doctors about the health conditions of animals and humans.
Buried dead body:
It is very important because, somehow, transmission will stop and the air will never be contaminated by LSD virus.
Use new or sterile syringes when doing vaccinations:
By using sterile syringes, we will be able to stop the mechanical transmission of viruses.
Vector:
Vectors can be controlled by repellents such as dichlorodiphenyltrichloroethane (DDT), deet (N, N-diethyl-m-toluamide), and permethrin, which are very effective in killing ticks, mosquitoes, and Culicoides.
We make sure that the environment where cattle are present is insect-free. By doing this, we stop the transmission of disease.
This article is jointly authored by Muhammad Ramzan, Laiba Imran from the University of Veterinary and Animal Sciences, Lahore subcampus Jhang, and Muhammad Qasim from the University of Agriculture Faisalabad.