4. DISCUSSION
This study was conducted to describe the first official outbreak of Lumpy skin disease (LSD) in the Gandaki Province of Nepal and to evaluate the clinical and epidemiological features of LSD in the study area. Two districts from Gandaki Province, Kaski, and Tanahun, were affected with the LSD where 16 animals (12 cattle and 4 buffalo) from 9 farms were confirmed positive for LSD. This is also the first laboratory-confirmed LSD outbreak in water buffalo from Nepal.
Before the outbreak of LSD in Gandaki province in early August 2020, this disease was also confirmed from three other provinces of Nepal, Province 1, Province 2, and Bagmati Province in late July 2020 (OIE, 2019d). The disease was confirmed in the Chitwan district of Bagmati province on July 27, 2020 (OIE, 2019d) which is adjoining to the Gandaki province. In around one week of its confirmation in Chitwan district, cattle and buffalo in Kaski and Tanahun district started developing clinical signs with fever, nodular lesions in the skin, swollen lymph nodes, nasal and lachrymal discharges, and reduced milk production which ultimately was laboratory confirmed as LSD. There was a history of animal import from Chitwan district, where LSD was officially confirmed, and Sarlahi where LSD has not been confirmed but its nearby districts had confirmed LSD cases in late July. As the cattle were imported a few months before the disease was confirmed in Chitwan, it was difficult to conclude that LSD came to Gandaki province from Chitwan. However, this possibility cannot be ignored as often diseases might go unnoticed for months and might silently circulate before they finally get noticed.
In this outbreak, the clinical features exhibited by the sick animals were swollen lymph nodes, nodular lesions in different body parts, nasal and lachrymal discharges, and fever. These clinical features are in confirmation with findings from other LSD outbreaks in various parts of the world (Sameea et al., 2017; Tuppurainen et al., 2018; Ochwo et al., 2019; Manic et al., 2019; Sudhakar et al., 2020). The morbidity rate of 4.85% with zero mortality in the current outbreak in Gandaki province was similar to that observed during the first LSD outbreak in Odisha state of India where 7.1% morbidity with zero mortality was observed (Sudhakar et al., 2020).
Veterinarians and technicians have been providing supportive treatment therapy to the affected animals using antibiotics, antipyretics, antihistamines, and ivermectin to control ectoparasites. The Government of Nepal has activated the quarantine system to control the animal movement from affected areas to clean areas. However, it needs to be more effectively implemented as the disease transmission has been continuing despite the official animal movement restriction. It was surprising to observe the spread of LSD over several districts despite these animal movement restrictions and the lockdown imposed to control the COVID-19 transmission causing limited long-distance transportation. The possibility of illegal animal movement cannot be ignored.
Experiences from prior LSD affected countries have shown that a combination of vaccination, animal movement regulation, and vector control is the best control strategy for LSD (Beard, 2016; Gupta et al., 2020). A homologous vaccine containing LSD virus or a heterologous vaccine containing either sheep pox or goat pox virus can be used to control the LSD (Kitching, 2003; Sprygin et al., 2020). Since the disease is relatively new in Nepal and was only confirmed in late July 2020, vaccines are yet to be available in Nepal.
In conclusion, LSD has been confirmed for the first time in Gandaki Province of Nepal in both cattle and water buffalo in the first week of August after its first confirmation in Nepal in July 2020 in the eastern part. The current morbidity and mortality are relatively low but milk production among affected animals was nearly 60% highlighting the possibility of huge economic losses it can cause to the dairy farmers of Nepal. To mitigate its potential negative impact before it becomes widespread in Nepal, we suggest the Government of Nepal decide on the appropriate vaccine for Nepal and develop a robust vaccination strategy and conduct risk-based ring vaccination surrounding the outbreak area. Besides, the animal movement needs to be regulated along with raising awareness among dairy farmers to practice biosecurity in their farms and apply vector control measures.
5. ACKNOWLEDMENTS
We acknowledge all the dairy farmers, Veterinary Hospital Kaski and Tanahun for their help to conduct this outbreak investigation.
6. CONFLICT OF INTERESTS
The authors declare that they do not have any conflict of interests.
7. FUNDING
There was no funding available for this study.
8. AUTHOR’s CONTRIBUTION
GKC and SK conceived the idea. GKC, BR and DKU collected the samples and field information. PK conducted the laboratory testing. SK analyzed the data and wrote the first draft of the manuscript. GKC created the map. KRP provided the overall supervision and guidance. SK and GKC revised the manuscript. All authors read and endorsed the final version.
9. ETHICAL STATEMENT
This study does not disclose farmer’s individual identifier. Consent were obtained from the farmers to use their data for analysis. Samples were collected by trained veterinarian registered in Nepal Veterinary Council causing minimum pain and discomfort to the animals. No interventions or trial were made on the animals.
10. DATA AVAILABILITY STATEMENT
All data are included within the manuscript.