Lumpy skin disease (LSD) is a viral disease of cattle caused by lumpy skin disease virus (LSDV) and is included in the OIE list of notifiable animal diseases because it has a major economic impact. It belongs to the genus Capripoxvirus of the family Poxviridae. It is a highly infectious and economically important trans-boundary disease of cattle. Morbidity rates vary between 10 to 20% with a 1-5% mortality rate (DLS, Situation Report: Lumpy Skin disease in Bangladesh ,2019).LSD was first identified in 1929 in Zambia and then spread to Egypt in 1988, still confined in Africa. Currently, LSD is endemic in most African countries. Since 2012 it has spread rapidly through the Middle East and southern and eastern Europe (OIE, 2017)). In 2015, the disease appeared in Russia, Greece, and Armenia (MCI report, 2020). Three countries in Asia have reported the first occurrence of the disease to OIE in 2019: Bangladesh (outbreak start date 14/07/2019), China (outbreak start date 03/08/2019) and India (outbreak start date 12/08/2019) (DLS, 2019). The first outbreak in Bangladesh was reported on 22/07/2019 (DLS, 2019). LSD is highly host specific, causing disease in cattle only and it is not zoonotic (MCI report, 2020).
Transmission and clinical signsThe transmission of LSDV mainly takes place mechanically by blood-feeding arthropods such as mosquitoes, stable flies, and ticks. Less commonly, the virus may be spread by direct contact to the skin lesions, saliva, nasal discharge, milk, or semen of infected animals (MCI report, 2020). The incubation period of LSD is 4to 28 days. It ranges from inapparent to severe disease. The clinical sign includes Fever (> 41°C), reduction in milk production, depression, anorexia and emaciation, rhinitis, conjunctivitis, excessive salivation and enlarged superficial lymph nodes (MCI report,2020).
Economic impact of LSD in Bangladesh
LSD is considered as one of the economically important diseases causing substantial production loss. Although the impacts of the disease are sometimes difficult to quantify but it leads to the great impacts on the economy of the country.The cost of animal disease depends on the losses related to animal illness, death, reduced production and losses in trade and other revenues (Rushton, 2009). LSD causes huge economic losses which include sharp decreased milk and beef production, loss of draft power, increased abortion rates, infertility, and damage to hides, mortality, increased treatment and vaccination costs, embargo on trades. Therefore, it may affect overall economy of the farmers as well as of the country (Gari et al., 2011). The study doneby Limon et al. (2020) and Gumbe (2018) also found similar economic losses. Since, cattle is one of the main components of ourlivestock sector, thus the outbreak of LSD may substantially impact on the livelihoods of small-scale farmers and poor rural communities, which make up most cattle owners in Bangladesh. The cost of providing supportive treatment for 2-3 months during the recovery period is unrealistic for many of these low-income families. According to DLS report (Situation Report: Lumpy Skin disease in Bangladesh, 2019), a total of 553,528 cattle was affected by LSD in all 8 divisions in 2019. However, the highest incidence occurred in Chattogram (8.26%) and Khulna (6.52%) and lowest in Sylhet (0.01%). (DLS, 2019) Again, in 2020 the LSD outbreaks are being reported in different areas of the country. It is noted that the crossbred cattle are more susceptible to LSDV infection compared to zebu cattle (Gari et al., 2011; Kiplagat et al., 2020). However, the disease severity in young animals (fattening animal) and cows in the peak of lactation is more pronounced causing sever loss to production (Al-Salihi, 2014).
Prevention and control strategy
As a vector borne disease, LSD is almost impossible to control without vaccination.The climatic conditions of Bangladesh are favorable for the propagation of vectors, especially in moon season (May- August), which may influence the rapid transmission of LSD in the cattle population in our country. Therefore, LSD may appear as a big challenge to cattle health in Bangladesh in near future.Vaccination has been proved as best tool for quick and effective control of LSD, as it reduces the total number of susceptible animals within the population and prevent entry and spread of the disease (EFSA, 2019). Heterologous vaccine (goat/sheep pox vaccine) induces an incomplete and weak protection compared to homologous vaccine (Neethling strain) which confers a solid and durable immunity (EFSA,2019,2020). Alexandrov (2018) and MCI (2020) reported that live attenuated Neethling strain vaccine provides best protection. ACI Limited has got approval from the government and recently introduced homologous attenuated Neethling strain vaccine (called BOVIVAX LSD) in Bangladesh from M.C.I Santé Animale Company. This vaccine is produced as per European GMP requirements and is also registered in the EU. Now we can prevent the disease in a better way using the readily available BOVIVAX LSD vaccine.
ConclusionBangladesh government is taking active steps to monitor and control the outbreak with messaging through posters, leaflets and awareness raising events and it has been strengthening border enforcement to slow the influx of cattle from India. The government is also trying to prevent the disease by local goat pox vaccine with limited scale. It also encouraged private sector like ACI limited to introduce Neethling strain vaccine in the country to prevent and control the disease. It is expected that Neethling strain vaccine (BOVIVAX LSD vaccine) will provide good protection in cattle. The BOVIVAX LSD vaccine in the presence of adequate bio-security will unlock the problem of lumpy skin disease and will protect the livestock farmers and livestock industry of Bangladesh. To limit the spread of LSDV infection, active surveillance and early detection are also very important because many farmers are not aware of LSDV infection and its impacts on animal health.
The writers are Chief Technical Advisor, Director of Sale, Business Manager and Product Manager respectively, ACI Animal Health