Lumpy Skin Disease (LSD) in Cattle: an Emerging Viral Disease
Dr.Namrata V. Patil1, Dr.Indica Sharma2
1Assistant Professor, Department of Veterinary Pharmacology and Toxicology, IIVER, Rohtak
2Assistant Professor, Department of Veterinary Microbiology, IIVER, Rohtak
Over the last few weeks, nearly 3,000 cattle have died in Rajasthan and Gujarat due to a viral infection called the Lumpy Skin Disease (LSD) that has spread across the states. On July 27, the Gujarat government banned the transport of livestock out of 14 affected districts. Around 11 lakh cattle have been vaccinated against the disease, and the National Dairy Development Board has supplied 28 lakh doses of goat pox vaccine to Gujarat, Rajasthan and Punjab, bought from a private entity called “Hester Biosciences”.
What is the Lumpy Skin Disease?
According to a report by GAVI, the Global Alliance for Vaccines and Immunisation, the Lumpy Skin Disease (LSD) disease is caused by a virus called the Capripoxvirus and is “an emerging threat to livestock worldwide”. It is genetically related to the goatpox and sheeppox virus family.
How does LSD infection spread?
LSD infects cattle and water buffalo mainly through vectors such as blood-feeding insects (such as Stomoxis, Glossina, Culicoides species), through contact with saliva, discharge from nose and eyes, and with semen and foetus. Outbreaks of infection and disease can last 2 to 3 weeks and sometimes even longer.
The disease resistance of the animal depends on its age, susceptibility to the breed as well. Severe cases of LSD are easier to identify or diagnose because of the skin symptoms. However, mild infections can be difficult to detect in the early stages, even for experienced veterinarians, because in addition to LSD, infection with the herpes virus can also lead to the formation of lumps on the skin.
What are the symptoms of LSD?
Animals infected with LSD have a high fever of 40 °C or 104 °F between 4 and 14 days. The discharge keeps coming out of their nose and eyes. Sores or knots begin to form on the skin. There is a drastic reduction in milk production. Skin lumps usually appear on the head, neck, back, abdomen, udder and genitalia within 48 hours of the onset of fever, enlarged sub scapular and pre-femoral lymph nodes.
In severe cases, the skin lesions cover the entire body. Sometimes animals are also attacked by pneumonia, sometimes a white spot of ulcer (lesion) is also formed in the cornea (pupil) of one or both eyes, which sometimes completely or partially destroys the infected animal but blind. From the time the first case of LSD is detected in an area to its control, between 5 and 45 percent of animals become ill. The mortality rate of animals exposed to this disease can be more than 10%.
Have Lumpy Skin Disease outbreaks occurred earlier? Are humans at risk?
This is not the first time LSD has been detected in India. The disease has been endemic in most African countries, and since 2012 it has spread rapidly through the Middle East, Southeast Europe and West and Central Asia. Since 2019, several outbreaks of LSD have been reported in Asia. In May this year, Pakistan’s Punjab also reported the deaths of over 300 cows due to LSD.
In September 2020, a strain of the virus was discovered in Maharashtra. Gujarat too has reported cases over the last few years sporadically, but currently, the point of concern is the number of deaths being reported, and whether vaccination catches up to the rate at which the disease is spreading.
According to the World Organisation for Animal Health (WOAH), of which India is a member, mortality rates of 1 to 5 per cent are considered usual. The disease is not zoonotic. While the virus does not spread to humans, “milk produced by an infected animal will be fit for human consumption after boiling or pasteurisation as these processes will kill the viruses, if any, in the milk”.
Goat pox vaccine approved in India
Live LSD vaccine is available for cattle in Africa. Due to this, sufficient immunity develops in the affected animals in about three weeks. There is currently no LSDV vaccine available in India. However, according to the Bengaluru-based ICAR- NIVEDI or National Institute of Veterinary Epidemiology and Disease Informatics or the National Institute of Veterinary Epidemiology and Informatics, the emergency use of goat pox vaccine is allowed in areas prone to LSD outbreaks in the country. Scientists of the same institute have also developed a special RT-PCR kit to test LSD.
Prevention & Control
Successful control and eradication of LSD relies on “early detection followed by a rapid and widespread vaccination campaign”, as per the WOAH. Once an animal has recovered, it is well protected and cannot be the source of infection for other animals.
In his interview with The Indian Express, Prof J B Kathiriya, also spoke about the measures to protest against the viral infection. He said, The first thing is, they should sanitise cattle-sheds by eliminating vectors through application of insecticides and spraying disinfectant chemicals. They should isolate the infected cattle immediately from the healthy stock and contact the nearest veterinarian for treatment of the infected animal. This is necessary as otherwise the virus may prove fatal. Secondly, they should report the outbreak to the state government so that the rest of the healthy herd can be vaccinated using goat pox vaccine,” said Prof Kathiriya. He added that cattle with healthy immune systems will recover from the disease in some days.
Another challenge is the disposal of the dead animals as improper handling of the carcasses can cause health and sanitation issues. Proper disposal of the carcasses can include incineration or burning of the bodies at high temperatures, along with disinfection of premises, as per the WOAH.
The disease can be prevented from becoming an epidemic by keeping infected animals in enclosures, treating them properly and sanitizing the person and vehicles that come in contact. In areas where LSD outbreaks are seen, use of mosquito nets or insect repellents, insecticide spraying around animal enclosures and fogging should be used to protect healthy animals from flies. Animals that die due to LSD should be buried in deep pits. Livestock farmers should strictly abstain from pastures in areas where LSD outbreaks are visible.
New animals should be purchased from LSDV free areas. New animals should be allowed to mingle with other animals only after they have been kept in a separate enclosure for at least 28 days. LSD viruses are highly sensitive to sunlight and lipid solvents containing detergents. Hence, infected animals get relief from the sun. Furthermore, it is possible that the main reason for the current surge may be an increase in vector populations from the monsoon – and a decrease for the same reason. But this only adds to the urgency to act now and launch a concerted vaccine-cum-awareness campaign on the lines of the fight against COVID-19. The dairy sector, which accounts for one-fifth of the gross value added to Indian agriculture, needs to be prepared for a new resurgence that could come soon – with deadly consequences.
The government should accelerate the commercialization of the recently developed live attenuated homologous vaccine of the Indian Council of Agricultural Research, which is said to provide complete protection against LSD. It may consider granting emergency use authorization to enable mass production and roll-out, as is the case for COVID vaccines. Vaccination should be done on mission mode, with push coming from above and not animal husbandry and dairy department.
Apart from this, to clean knots and wounds with solutions of substances like phenyl (2%), sodium hypochlorite (2-3%), iodine compound (1:33 dilution), vircano (2%), quarantine ammonium compound (0.5%). Viruses start becoming inactive. Any treatment should be done on the advice of a veterinarian.
Measures to protect animals from this disease:
- Disease animals should be kept separate from healthy animals
- Animals showing symptoms of disease should not be taken to fair, market and exhibition.
- Control of number of pests in the farm, mainly mosquito, fly, flea.
- The goods used in the examination and treatment of sick animals should not be thrown in the open and the waste material should be destroyed by proper management.
- If you see an animal with any unusual symptoms on or near your farm, it should be reported to the nearest veterinary hospital immediately.
- The worker of one farm should not go to another farm, along with this the worker should also pay attention to the cleanliness of his body.
- Workers caring for infected animals, stay away from healthy animals or take care of healthy animals by wearing clean clothes after bathing.
- There should be proper arrangement for the cleanliness of the entire farm, cleaning the floor and walls should be done using phenol (2 percent) or iodized insecticide solution (1:33) for cleaning the walls.
- Utensils and other useful items should be disinfected with chemicals. For this, detergent powder, sodium hypochloride, (2–3 percent) or quaternary ammonium salt (0.5 percent) should be used for cleaning dishes.
- If an animal dies after suffering from skin disease for a long time, it should be taken away and buried in a pit.
- The bulls that have been cured of this disease, their blood and semen should be tested in the laboratory. If the results are good, only then their semen should be used.
- Antibiotics can be used as needed to protect the sick animals. Medicines should be used only according to the advice of the doctor.
