The lumpy skin disease or the LSD which is now under the limelight in Nagaland, infecting over 900 lives of cattle in Nagaland. Lumpy skin disease (LSD) is a notifiable disease, according to World Animal Health Organization (OIE), because of its rapid spread and economic losses. Lumpy skin disease was initially seen as an Epidemic in Zambia, South Africa in 1929. In 2022, in India between July- September the LSD was first reported which resulted in over 80,000 deaths of cattle with Rajasthan having a lead in the death tolls. The first LSD was reported in Gujarat and has spread to eight states/union territories by now. The recent wave, since May-June 2022, was unusual not only for morbidity or the rate at which animals were contracting the disease, but also mortality. The outbreak of disease in 2022 had infected around 29.45 lakh cattle, caused nearly 1.55 lakhs deaths, and was spread to 251 districts in 15 states of India. On 27th July 2023, Nagaland was declared a lumpy skin disease positive state and has been detected in 8 out of 16 districts.
Lumpy skin disease is an infectious viral disease of cattle. The disease is characterized by high fever and enlarged superficial lymph nodes on the skin and peculiar multiple nodules or lumps on the skin. It can also lead to death, especially in animals that have not previously been exposed to the virus or have low immunity. It is transmitted by blood-sucking insects, such as certain species of flies, mosquitoes, and ticks. LSD is a highly host-specific disease. It primarily affects cows and a less extend in buffalo. Morbidity rate is higher in Cattle than Buffalo. It affects calves and heifers more as compared to adult animal in the case of cattle.
Lumpy skin disease (LSD) is a viral infection caused by the lumpy skin disease virus (LSDV) of the Capripoxvirus genus in the poxviridae family. LSD virus is identical to sheep pox virus (SPV), and goat pox viruses (GPV) which are closely related although differ phyto-genetically. LSD virus is also known as Neethling virus.
The virus transmission occurs through the movement of animals or unrestricted movement of stray animals. Infected animals excrete viruses in saliva as well as in nasal and ocular discharges. It can remain in saliva for 11 days (after the development of fever). The virus can be found in skin nodules even after 33 days of infection. The virus primarily transmitted by arthropod vectors like common biting flies, mosquitoes, and some ticks. The multiplication of vectors during the monsoon months causes faster spread of the disease. The virus also persists in the semen of infected bulls, so natural mating and artificial insemination can also spread the disease. Thus, it is advisable to use bulls after 22 days of intervals for mating. Disease can also spread from females to calves with skin nodules; suckling calves can get infection from milk and from skin nodules in teat. Virus remains in the skin nodules for 33 days.
The symptoms of the disease are not restricted to the mere appearance of skin nodules. In most of the cases, diseased animals are experienced severe pain, limbs swelling, loss of appetite and fever along with bleeding from the nodules. Initially lacrimation, nasal and ocular discharge and excess salivation is observed. Enlarged lymph nodes mainly sub-scapular and pre-femoral lymph node which are easily palpable. The disease affects mainly the legs of cattle, which get swollen, followed by high fever (>104ºF) which persists for a week. There may be sharp reduction in milk yield. Skin lesions or nodular skin is highly characteristic symptom of this disease. Blindness may occur in worst cases due to ulcerative lesions in cornea in one or both eyes. Secondary bacterial infection in joints and legs leads to lameness in severe case, pneumonia and mastitis also observed. During post mortem examination, pock lesions can be found on the entire digestive and respiratory tract and on every internal organ. Pregnant cows may abort and remain in anoestrous(period of sexual inactivity between two periods of oestrus) for several months.
There is no scientific proof so far that lumpy skin disease is a zoonotic disease which can spread from animals to humans or vice versa. During infectious period, the LSD virus may be transmitted to suckling calves through contaminated milk, or from skin lesions in the teats. However, there is no evidence regarding transmission of the LSD infection to humans through milk. However, it is recommended to carry out the basic food hygiene principles e.g., proper boiling of the milk in order to stay safe from many of the other foodborne pathogens.
Proper disposal of the carcasses also plays an important role in controlling the spread. According to World Organization for Animal Health (WOAH) proper disposal of the carcasses can include incinerationor burning of the bodies at high temperatures, along with disinfection of premises. Ensure proper burial of dead animals, carcasses of affected animals should be disposed of through incineration or buried in a 6x6x6 ft.3 pit with lime.
The outbreak of the Lumpy skin disease posed severe, broad and long-term effects on the livestock industries. The expenses of an animal disease outbreak can roughly be divided into direct loss, which includes loss of milk, reproductive failure, treatment cost and preventive cost (vaccination, sanitization, vector control etc.). However, indirect losses encompass labour costs, disposal cost, transportation costs, damage to hide, reduction in selling value and reduction in drought power. Sometimes due to information scarcity, impacts of the other direct losses like infertility, abortion, reduced body weight and culling were not considered during the quantification of the total loss.
Any livestock suspected of nodular skin disease along with fever should be isolated from the rest of the herd. If pox like lesions is observed in many animals simultaneously at the farm, take advice from a local veterinarian as soon as possible. In villages and affected regions, the infected animals should be kept isolated from healthy animals and barred from common grazing and thus to prevent direct contact with healthy animals. The movement of herdsmen to and from the infected premises should also be banned.
The caretaker, who is attending to the diseased animals, should be kept away from the healthy herd. Though it is not transmitted from animals to humans or vice- versa, it is advisable not to consume products from an infected animal. TheLumpyvax vaccine can be used for prophylactic immunisation against LSD. If it is not available, goat pox vaccine can be used for cattle above 4 months of cattle yearly.
In order to control lumpy skin disease, the movement of animals to and from the infected area should be completely restricted. This will check the transmission/spread of LSD. Cattle markets located within 10 km radius of the epicentre of infection should be closed. Ensure strict control of animal movement from affected areas to free areas and to local animal markets. When a particular area is found affected with disease, all trade of live cattle, participation in animal fairs, shows etc. should be banned immediately.
LSD outbreaks control strategies includes mass awareness of LSD restriction of animal movement, isolation of infected animals, monitoring of stray animals, cleaning and disinfection of the premises and insect control and finally safe disposal of carcasses should be fully executed. Preventive vaccination in mission mode should also be undertaken in high risk areas like border area of affected districts and states and affected animals should be identified documented.
By: Arentila
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