Comparison of the efficacy of Neethling lumpy skin disease virus and x10RM65 sheep-pox live attenuated vaccines for the prevention of lumpy skin disease – The results of a randomized controlled field study
Introduction
Lumpy skin disease (LSD) is a re-emerging economically significant disease of cattle, caused by the lumpy skin disease virus (LSDV), of the genus Capripoxvirus [1]. The virus is believed to be transmitted mechanically by blood feeding flying insects such as Stomoxys sp. and Aedes sp. [2] and potentially by ticks [3], [4], [5], [6], [7], [8].
In Israel the disease was first recorded in 1989 [9] and afterwards in 2006–2007 [10]. In both epidemics it was suspected that the virus arrived from Egypt by wind borne arthropod vectors [11]. In 1989 all livestock in the infected village were culled, including sheep and goats. These control measures were followed by ring vaccination of the surrounding herds. In the epidemics which occurred during 2006–2007 only clinically infected animals were slaughtered and quarantine was applied to all affected herds. Along with this the entire southern region of Israel was vaccinated, using subcutaneous injection of 1 ml of an attenuated sheep pox vaccine of the RM65 strain (Abic®, Israel) (102.5 TCID50/ml).
On late July, 2012 first suspected cases of LSD were reported from several beef herds located in north-eastern Israel, near the borders of Israel with Syria and Lebanon. The epidemic kept advancing southward despite the implementation of movement restrictions and emergency vaccination with an attenuated sheep pox vaccine of the RM-65 strain (Jovivac™, Jovac®, Jordan) (102.5 TCID50/ml). On October, 2012 first cases began to appear among intensive zero-grazing high producing Holstein dairy cattle herds and reached its peak at the spring of 2013. During April alone 70 new herds were affected, including more than 40 new dairy herds. At this stage the disease has spread among the herds in the entire northern part of Israel, with one isolated foci in the center of Israel more than 100 km south, probably due to unauthorized movement of sick cattle (the affected farms apart of this isolated foci are depicted in Fig. 1). The failure of controlling the outbreak by using the attenuated RM65 sheep-pox vaccine, in its original concentration (102.5 TCID50/ml) led the Israeli Veterinary Services to take a decision, on March the 18th 2013, to vaccinate all cattle in Israel against LSD, using the attenuated RM65 sheep-pox vaccine in a 10× dose (x10RM65) and the attenuated Neethling lumpy skin disease vaccine (OBP®, Republic of South-Africa). Roughly, almost all dairy herds were vaccinated within 3 months with the Neethling vaccine while most of the feedlots and beef cattle herds were vaccinated with the x10RM65 vaccine.
The current study was planned, parallel to this campaign, aiming to evaluate the field efficacy and safety of the two vaccines during the ongoing LSD epidemic which occurred in Israel. Both vaccines were used for the first time in Israel, and to the best of our knowledge their efficacy was never compared previously under field conditions.
Section snippets
Study population
The study was conducted in 15 commercial dairy herds in the north of Israel in which no LSD was documented prior to the study onset. (Fig. 1, Table 1). These herds accommodated a total of 8480 animals (cows, heifers, suckling calves). All participating herds held proper restriction facilities, which enabled animal identification and proper vaccination technique.
Prior vaccination
As a part of the initial attempts made by the veterinary services to mitigate the outbreak, all herds were vaccinated subcutaneously
Results
LSD was detected and confirmed in 8 herds out of the 15 farms participating in the study. Morbidity in the affected farms ranged from 0.3% to 5.7%. Eighty-nine animals developed clinical signs of LSD (an overall incidence of 1.6%). Of these 51 were x10RM65 vaccinated (incidence of 1.85%), 31 were Neethling vaccinated (incidence of 1.11%) and 7 were unvaccinated calves located in one herd, which were born after vaccine administration (7 of 59 calves borne in this herd after vaccination (an
Discussion
The RM65 strain based vaccine was used to prevent LSD in Israel after outbreaks which occurred in 1989, 2006 and 2007. However, the incidence in some herds vaccinated with this vaccine, at least once and up to 3 times prior to the outbreak of 2007 reached up to 44% [15]. This prior experience combined with the observation of high LSD incidence in RM65 vaccinated beef herds during the outbreak of 2012 indicated that the effectiveness of the RM65 vaccine was very limited and motivated the
Conclusion
Though the current study supports the use of the Neethling vaccine for protection against lumpy skin disease, its use should be considered against the potential adverse effects associated with its administration and the risk of inserting an actual disease agent into a potentially naïve country. Choosing the right vaccine should be based on consideration of the advantages and disadvantages of each vaccine and tailored to the specific situation in each country.
Acknowledgments
This study was supported by a grant from the Israeli Veterinary Services.
Conflict of interests: The authors do not have any conflict of interest to declare.
References (22)
- et al.
Evidence of vertical transmission of lumpy skin disease virus in Rhipicephalus decoloratus ticks
Ticks Tick Borne Dis
(2013) - et al.
Demonstration of lumpy skin disease virus infection in Amblyomma hebraeum and Rhipicephalus appendiculatus ticks using immunohistochemistry
Ticks Tick Borne Dis
(2014) - et al.
Appearance of skin lesions in cattle populations vaccinated against lumpy skin disease: statutory challenge
Vaccine
(2009) - et al.
Development of an assay to differentiate between virulent and vaccine strains of lumpy skin disease virus (LSDV)
J Virol Methods
(2014) - et al.
Characterization of sheep pox virus vaccine for cattle against lumpy skin disease virus
Antiviral Res
(2014) - et al.
Evaluation of the safety, immunogenicity and efficacy of three capripoxvirus vaccine strains against lumpy skin disease virus
Vaccine
(2015) - et al.
Lumpy skin disease: an emerging threat to Europe, the Middle East and Asia (Review)
Transbound Emerg Dis
(2011) - et al.
Mechanical transmission of lumpy skin disease virus by Aedes aegypti (Diptera: Culicidae)
Epidemiol Infect
(2001) - et al.
Detection of lumpy skin disease virus in saliva of ticks fed on lumpy skin disease virus-infected cattle
Exp Appl Acarol
(2013) - et al.
Mechanical transmission of lumpy skin disease virus by Rhipicephalus appendiculatus male ticks
Epidemiol Infect
(2013)
Evidence of lumpy skin disease virus over-wintering by transstadial persistence in Amblyomma hebraeum and transovarial persistence in Rhipicephalus decoloratus ticks
Exp Appl Acarol
Cited by (90)
Qualitative assessment of the probability of introduction and onward transmission of lumpy skin disease in Ukraine
2022, Microbial Risk Analysis