The story so far: Mumbai Police have ordered a ban on the transportation of livestock in the city to prevent the spread of lumpy skin disease. This means that livestock cannot be moved from where they are raised or taken to markets. The order went into effect on September 14 and will remain in effect until October 13. The disease killed 127 cattle in Maharashtra, and spread to 25 districts. The infectious viral infection in cattle has spread to more than 10 states and union territories so far. Prime Minister Narendra Modi last week informed that the center and countries are working together to control the spread of the disease which has emerged as a concern of the dairy sector.
What is lumpy skin disease and how does it spread?
Nodular skin disease is caused by the lumpy skin disease virus (LSDV), which belongs to the genus Capripoxvirus, and is part of the smallpox family (pox and monkeypox viruses are also part of the same family). LSDV shares antigenic similarities with sheep pox virus (SPPV) and goat pox virus (GTPV) or is similar in immune response to those viruses. It is not an animal virus, which means that the disease cannot spread to humans. It is an infectious disease transmitted by disease vectors such as mosquitoes, some biting flies and ticks and usually infects host animals such as cows and water buffalo. According to the Food and Agriculture Organization of the United Nations (FAO), infected animals excrete the virus through oral and nasal secretions that may contaminate shared feed and ponds. Thus, disease can be spread either through direct contact with vectors or through contaminated feed and water. Studies have also shown that it can be spread through an animal’s semen during IVF.
LSD affects the affected animal’s lymph nodes, causing the nodes to swell and look like lumps on the skin, hence its name. Skin nodules with a diameter of 2-5 cm appear on the head, neck, limbs, udder, genitals, and perineum of infected cattle. The nodules may later turn into ulcers and eventually develop into scales on the skin. Other symptoms include high temperature, a sharp decrease in milk production, discharge from the eyes and nose, drooling, loss of appetite, depression, skin damage, emaciation of animals (thin or weak), infertility and miscarriage. The incubation period, or the period between infection and symptoms, is about 28 days according to the FAO, and 4 to 14 days according to some other estimates.
The incidence of the disease ranges from 2 to 45%, while the fatality rate or death rate so far is less than 10%, however, the reported mortality rate for the current outbreak in India is as high as 15%, especially in the cases reported in the part western (Rajasthan) of the country.
What is the geographical distribution and how did it spread to India?
The disease was first observed in Zambia in 1929, and later spread to most African countries on a large scale, followed by Western Asia, Southeast Europe, Central Asia, and more recently to South Asia and China in 2019. According to the Food and Agriculture Organization, LSD is currently endemic in Several countries across Africa, parts of Western Asia (Iraq, Saudi Arabia, Syrian Arab Republic) and Turkey.
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The outbreak in South Asia first hit Bangladesh in July 2019 and then reached India in August of that year, with initial cases detected in Odisha and West Bengal. The Food and Agriculture Organization notes that: “The long, porous border between India, Nepal and Bangladesh allows for a great deal of bilateral and informal trade of animals, including cattle and buffalo.” The UN says this may have contributed to the spread of LSD in July and August 2019 between Bangladesh and India. While the 2019 outbreak subsequently subsided, the most recent outbreak in India began in June of this year.
Is it safe to eat milk from infected cattle?
Studies indicate that it has not been possible to confirm the presence of viable LSDV virus prepared in milk derived from an infected animal. However, the Food and Agriculture Organization notes that a large portion of milk in Asia is processed after it has been collected and is either pasteurized, boiled or dried in order to make milk powder. This process ensures that the virus is inactivated or destroyed.
Notably, the joint director at the Indian Veterinary Research Institute (IVRI) told PTI that it was safe to ingest the milk of cattle infected with strep skin disease, as it is a non-zoonotic disease.
“It is safe to drink the milk of infected cattle,” said Mr. Mohnty. “There is no problem with the quality of the milk even if you have it after boiling or without boiling.”
What are the economic repercussions?
The spread of the disease can lead to “significant” and “serious” economic losses according to the Food and Agriculture Organization and the World Organization for Animal Health (WOAH). The disease leads to reduced milk production as the animal becomes weak and also loses appetite due to mouth ulceration. Income losses can also be due to poor growth, reduced ability to withdraw and reproductive problems associated with miscarriage, infertility, and lack of IVF semen. The ban on movement and trade after the injury also put economic pressures on the entire value chain.
An FAO risk assessment study based on information available from 2019 to October 2020 revealed that the economic impact of LSD on countries in South, East and Southeast Asia was “estimated at up to $1.45 billion in direct livestock and production losses”.
The current outbreak in India has emerged as a challenge to the dairy sector. India is the largest milk producer in the world at about 210 million tons annually. India also has the largest number of cattle and buffalo worldwide.
In Rajasthan, which is experiencing the worst impact of lumpy skin disease, this has resulted in reduced milk production, which is reduced by about three to six liters per day. Reports indicate that milk production has also decreased in Punjab due to the spread of disease.
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According to the Food and Agriculture Organization, the disease is seriously threatening the livelihoods of small poultry farmers. It should be noted that farmers in Uttar Pradesh and Punjab have incurred losses due to livestock deaths and are seeking compensation from their state governments.
How bad is the current outbreak in India and what is the government doing?
The current outbreak started in Gujarat and Rajasthan around July and spread to Punjab, Himachal Pradesh, Andaman, Nicobar and Uttarakhand by early August. Then it spread to Jammu and Kashmir, Uttar Pradesh and Haryana. In recent weeks, it has been reported in Maharashtra, Madhya Pradesh, Delhi and Jharkhand. The virus has infected more than 16 cattle in 197 counties as of September 11. Of the approximately 75,000 head of cattle killed by the disease, more than 50,000 cattle, mostly cattle, were reported from Rajasthan.
FAO has proposed a set of measures to combat the spread of LSD, which include vaccinating susceptible populations with coverage of more than 80%, monitoring and quarantine of cattle animal movement, implementing biosecurity through disease vector control through sterilization of barns and spraying insecticides, and promoting activity and effectiveness. Passive surveillance Spread awareness about risk mitigation among all relevant stakeholders, and establish large protection and control areas and vaccination areas.
The Federation’s Department of Fisheries, Animal Husbandry and Dairy said the goat pox vaccine is “highly effective” against LSD and is being used in all affected states to contain the spread of the disease. As of the first week of September, 97 doses of the vaccination have been administered. Affected states have imposed bans on movement, isolating infected cattle and buffaloes, spraying pesticides to kill vectors like mosquitoes, and some affected states such as Maharashtra, Rajasthan, Delhi and Uttar Pradesh have set up dedicated control rooms and helpline numbers to guide farmers who have infected their livestock.
In a major achievement, two institutes from the Indian Council of Agricultural Research (ICAR) have developed a home-grown LSD vaccine, which the center plans to commercialize and roll out in the next three to four months. The vaccine is based on samples of LSD virus from cattle in Ranchi infected in the 2019 outbreak, and experimental trials on animals infected in the ongoing vaccine outbreak in 2022 have revealed encouraging results, ICAR and the Ministry of Agriculture report.