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Explainer: What Is Lumpy Skin Disease and Why Is it Raising Concerns?

Explainer: What Is Lumpy Skin Disease and Why Is it Raising Concerns?

Photo: Twitter/@momanyink

Kochi: As of August 8, more than 4,000 cattle have died in India due to a viral disease – the lumpy skin disease. The disease has also caused a significant dip in daily milk production in states like Gujarat.

Over the last month alone, the viral disease has been established in livestock across at least eight states in India. The Union minister for animal husbandry held a review meeting on August 7 to take stock of the situation. States are quickly trying to procure the goat pox vaccine – which has been shown to be effective in preventing the disease – to vaccinate livestock in affected areas.

But what is the lumpy skin disease and why is it raising such concerns? The Wire breaks it down.

What is LSD?

Like COVID-19, the lumpy skin disease is caused by a virus. The lumpy skin disease virus, as it is called, belongs to the genus Capripoxvirus, from the same family as the smallpox virus and monkeypox virus (Poxviridae).

The virus usually infects ruminants, such as cows and buffaloes. Fever is a common symptom of the disease. Lesions or wounds appear a week later, as does discharge from the infected animals’ eyes and nose. They salivate and go off food. The LSD virus also affects the animals’ lymph nodes. Lymph nodes enlarge, and they appear as lumps on the skin of infected animals – which lends its name to the disease. Animals infected by the virus also experience infertility, higher rates of abortions and severe emaciation.

All these impacts on animals’ health affect milk production. An assessment study by the FAO concluded that the economic impact of LSD for south, east and southeast countries is estimated to be up to $1.45 billion in direct losses of livestock and production. These losses may be higher due to the severe trade implications for infected countries, the report said. The disease is known to also affect meat production, hide quality and reproductive efficiency in cattle.

Infected animals can also succumb to the disease. However, though morbidity (or the condition of having the disease) is high (up to 45%), mortality – or death in infected animals – is not very high (at less than 10% – which means that only 10 out of 100 animals that contract the disease die from it), as per studies. In India, the mortality rate is just around 7%.

Spread of LSD

So how does the disease spread? It is known to be spread by insects, specifically bloodsuckers such as some species of biting flies and mosquitoes. It also spreads through contaminated food and water (such as common sources of drinking water, or even grazing grounds). Studies have found that instances of the disease increase significantly during summer and with the onset of seasonal rains – which coincides with the peak activity of the disease-transmitting vectors (such as flies and mosquitoes). Studies suggest that apart from increased movement of livestock or vectors across borders, climate change and increased illegal trade could be causing the spread of LSD as well.

Scientists reported the first case of LSD from Zambia in 1929. It later surfaced in several south and north African countries. Scientists have also identified LSD in wild animals in Africa (in giraffes, impalas etc). Later on, it spread to countries in the Middle East, including Israel, Kuwait, Oman and Yemen (in the 1990s). LSD was thought to be endemic to parts of Africa and the Middle East, but the disease has now surfaced in several countries across the world, including the European Union. As per a qualitative risk assessment conducted by the Food and Agriculture Organisation in 2020, the disease had spread to 23 countries in south, east and southeast Asia by October 2020. In fact, the expansion of LSD’s geographic range in south Asia is emerging as a challenge for Asian livestock management and food security, a recent study concluded. However, it is not known to transmit to humans.

In India, LSD was first reported in cattle in 2019 in West Bengal. By January 2021, it had spread to 15 states in the country, as per several news reports. According to one study, the disease may have spread to India from other adjoining countries due to livestock movement across international borders, or even due to the movement of disease-causing vectors across neighbouring countries.

The Indian scenario

Over the last month alone, the viral disease has been reported in at least eight states in India. These are Rajasthan, Punjab, Gujarat, Himachal Pradesh, Madhya Pradesh, Uttarakhand, Andaman and Nicobar Islands and Haryana.

Rajasthan has been worst hit by the latest LSD outbreak with 11 districts reporting a surge in cases, said Union animal husbandry minister Purushottam Rupala on August 7. The minister had arrived in Jaipur with a central team to take stock of the disease-affected areas.

In Madhya Pradesh, suspected cases of LSD have been reported from livestock in Ratlam district, as per news reports. More than 2,100 cases of LSD have been reported from Yamunanagar district in Haryana, reported Hindustan Times on August 7.

Dairy farmers are worried about the impacts that the disease is causing on milk production. LSD has caused a dip in milk production in Gujarat, by ~1,00,000 litres per day, reported The New Indian Express. It said that dairy unions in Saurashtra and Kutch reported a 15-20% reduction in daily milk collection.

Considering these impacts on milk production, the disease could have serious ramifications for the Indian dairy industry. India, incidentally, is the largest producer of milk in the world and contributes to 22% of total global production.

Cattle have also succumbed to the disease in many states. More than 1,200 cattle have died in Gujarat alone; as have more than 3,000 cattle in Rajasthan, and more than 400 in Punjab.

How is India tackling LSD and its spread?

Once animals contract the LSD virus, there is no treatment. Veterinarians, however, recommend isolating infected cattle and quarantining them. This is what many states in India are currently doing. In Uttarakhand, as in other states, infected animals have been isolated and affected areas have been turned into a containment zone to prevent the spread of the disease, the Times of India quoted Dr. Prem Kumar, director of the animal husbandry department in the state, as saying. Restricting cattle movement is one of the most crucial steps that needs to be taken to prevent the spread of the disease, studies say. Restricting vector movement, though more difficult, is possible too – through the use of insecticides or insect traps to kill flies and mosquitoes. A live attenuated vaccine is available for LSD. But since the LSD virus is closely related to the goat pox and sheep pox viruses, these vaccines can be used for cattle as a preventive measure as well.

This, in fact, is what many states in India are rushing to do. Punjab has already procured 66,000 doses of goat pox vaccine which will be administered free of cost to the healthy livestock, reported PTI on August 7. The state has also disbursed Rs 76 lakh to all districts to tackle the issue, the report said.

Mass vaccination of cattle and limiting inter-district movement are the two major steps needed to prevent the further spread of the disease, Ravi Murarka, President of the American Association of Veterinarians of Indian Origin told the PTI on August 6.

In late July, the Gujarat state government – in a high level meeting chaired by Chief Minister Bhupender Patel – decided to provide free vaccination for cattle in villages within five km radius of affected areas in 15 districts where LSD has been established, reported Times of India. In a meeting with animal husbandry officials on August 7, Patel also urged officials to dispose of dead cattle quickly.

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