Lumpy Skin Disease Virus And Secondary Bacterial Infection
Lumpy skin disease (LSD) is a viral disease of cattle caused by lumpy skin disease virus (LSDV). LSDV is one of the important animal poxviruses.
Organization of animal health categorizes LSD as a notifiable disease. Which become drastic with secondary bacterial infection. These bacteria are opportunistic pathogens in animals. LSDV infection shows wounds over the skin of cattle’s and this invite opportunistic pathogens to produce secondary infection.
Symptoms of LSD
LSD is characterized by fever, reduced milk production and skin nodules. Mastitis, swelling of peripheral lymph nodes, loss of appetite, increased nasal discharge and watery eyes are also common.
The incubation period of LSDV is about one week. i.e after one week we can get visual symptoms of LSDV infection, secondary bacterial infection in the affected skin lesions can increase the severity and prolong the course of the disease.
onset of fever occur approximately after one week of the infection. Initial fever may exceed to 106 F and may persist for one week. At the same time almost all superficial lymph node become enlarged.
Classification of LSDV
Lumph skin disease virus is one of the member of genus Capripoxvirus that are important pathogens of ungulates. Other members of this genus include sheep pox virus, and goat pox virus are isolated from african cattle, sheep and goats of Asia and Africa, respectively.
Lumpy skin disease virus is a double-stranded DNA virus. The genomic sequence of these three members of capripoxvirus are available and they average about 150 kb. The genome of these viruses are highly conserved, being 96% identical at the nucleotide level. The capripoxviruses also have highest AT content among the chordopoxviruses at 73 to 75%.
Other members of capripoxvirus are well know since ancient time and their spread has also been studied. Lumpy skin virus was only identified in 1929. This suggests that lumpy skin disease is in fact an old disease that was only recently identified, but the true evolutionary history and spread of the capripoxviruses is still an unresolved issue.
Structure Of Lumpy Skin Disease Virus
Like other members of poxviridae family, capripoxviruses are brick shaped. The average size of capripoxvirions is 320 nm by 260 nm.
Transmission Of Lumpy Skin Disease Virus
Blood feeding insects such as mosquitos and flies act as mechanical vectors to spread the disease. Outbreaks of lumpy skin disease tend to be sporadic since they are dependent upon animal movement, immune status and wind and rainfall patterns, which affect the vector population.
Most cattle develop lifelong immunity after recovery from a natural infection. Additionally, calves acquire maternal antibodies and are resistant to clinical disease until about 6 month of age from an immune cows. It is not advisable to vaccinate calves under 6 months of age whose dams were naturally infected or vaccinated. However, calves born form susceptible cows are also susceptible and should be vaccinated.