What is lumpy skin disease that killed nearly 100K cattle in India?

A viral disease, known as lumpy skin disease (LSD), has killed nearly 100,000 cows and buffaloes in India and sickened over 2 million more.

The first cases in South Asia were detected in 2019, and it has since spread to India, China, and Nepal. 

The virus was first recorded in Zambia in 1929 and has extended through Africa and more recently to parts of Europe.

Now, it has spread to at least 15 Indian states with the number of cow and buffalo deaths nearly doubling in three weeks, the Press Trust of India (PTI) news agency reported.

Western Rajasthan state has seen the worst impact with 60,000 cattle dead and nearly 1.4 million sickened.

How does the disease spread?

The disease is spread by "blood-feeding insects, such as certain species of flies and mosquitoes, or ticks, explains the European Food Safety Authority (EFSA).

Infected cows and buffaloes get fevers and develop lumps on their skin. The EFSA says it can also lead to death, "especially in animals that that have not previously been exposed to the virus". 

READ MORE: Bangladesh dwarf cow gunning for world title dies from stomach swelling

Infected animals spread the virus through oral and nasal secretions which may contaminate common feeding and water troughs, according to the United Nations Food and Agriculture Organisation (FAO).

Other symptoms include immediate weight loss, lesions in the mouth, reduced milk yield, pregnant cows and buffaloes often suffer miscarriage, and even death.

Is there a vaccine or any cure?

India is the world's largest milk producer, making up more than a fifth of global production - but exports are only a fraction of this.

To try and protect the industry, authorities are vaccinating healthy cows using a shot designed for a similar disease while efforts are underway to develop a more effective vaccine.

Goatpox, sheeppox and LSD viruses belong to the same capripoxvirus genus, explains India Express. 

Vaccines have been developed for the first two, and offer up to 60-70 per cent cross-protection against LSD in cattle.

What is being done to stop the spread?

Prime Minister Narendra Modi said last week that the "Centre and States are working together to control the spread of the disease, which has emerged as a concern for the dairy sector," reports The Hindu.

In bordering Uttar Pradesh state, India's most populous, the trade and movement of cattle with neighbouring states has been curbed.

Farmers in affected states, like the Himalayan Himachal Pradesh, have also urged the government for financial aid.

What is different about this outbreak?

A study of the LSD virus' genetic makeup found that it was very different from previous versions, said Vinod Scaria, a scientist at the Institute of Genomics and Integrative Biology in New Delhi.

Viruses evolve all the time and not all these changes are harmful to health. But Scaria, who is one of the study's authors, said it exposed the need for continuous monitoring and tracking of diseases since it wasn't clear how the virus evolved in the past two years. 

“If you had continuous surveillance, you would be prepared," he said.

Can the virus infect humans?

It is important to note the virus is not a zoonotic virus, meaning the disease cannot spread to humans. It is also unlikely the virus would pass through to us from the milk of infected animals.

The FAO says that a large portion of the milk in Asia is processed after collection and is either pasteurised, boiled or dried in order to make milk powder — a process that ensures the virus is destroyed.

READ MORE: 'All my goats are dead': Somalis leave homes to escape drought, starvation

The Joint Director at the Indian Veterinary Research Institute (IVRI) told PTI that it is safe to consume milk from cattle infected by the disease, reports The Hindu.

What are the economic implications?

The outbreak has triggered devastating income losses for cattle farmers since the disease not only results in deaths but can also lead to decreased milk production, emaciated animals, and birth issues.

The contagion spreading among cattle is having a disproportionate impact on small farmers, many of whom have insulated themselves from the shocks of climate change by rearing cattle for milk, said Devinder Sharma, an agriculture policy expert in northern Chandigarh city.

“It's a serious, serious issue and this (disease) … has been growing since the last couple of years,” he said, adding that the government figures were likely an undercount of the actual death toll from the disease.