Mass Vaccination Has Led to the Elimination of Rabies Since 2014 in South Korea
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Original article CLINICAL Mass vaccination has led to the EXPERIMENTALCROSSMARK_logo_3_Test 1 / 1 VACCINE elimination of rabies since 2014 RESEARCH in South Korea https://crossmark-cdn.crossref.org/widget/v2.0/logos/CROSSMARK_Color_square.svg 2017-03-16 Clin Exp Vaccine Res 2017;6:111-119 https://doi.org/10.7774/cevr.2017.6.2.111 pISSN 2287-3651 • eISSN 2287-366X Dong-Kun Yang1, Ha-Hyun Kim1, Purpose: Rabies is one of the most fatal diseases, but it is 100% preventable in animals by Kyoung-Ki Lee1, Jae-Young Yoo1, vaccination. In this study, we present the epidemiological features of, and national preventive 2 1 Hong Seomun , In-Soo Cho measures against, rabies in Korea. 1Viral Disease Division, Animal and Plant Quarantine Agency, MAFRA, Gimcheon; 2National Materials and Methods: Data related to rabies and the population density of raccoon dogs Institute of Biological Resources, Ministry of in Korea were collected from the Animal and Plant Quarantine Agency, the Korean Centers Environment, Incheon, Korea for Disease Control and Prevention, and the National Institute of Environmental Research. Ra- Received: February 6, 2017 bies diagnosis was confirmed with a fluorescent antibody test using brain samples of animals Revised: April 21, 2017 Accepted: May 2, 2017 in accordance with the procedures described by the World Organization for Animal Health. Corresponding author: Dong-Kun Yang, PhD, DVM Serological assays for dogs and cattle were conducted using the fluorescent antibody virus Viral Disease Division, Animal and Plant Quar- neutralization test. antine Agency, MAFRA, 177 Hyeoksin 8-ro, Gimcheon 39660, Korea Results: From 1993 to 2016, a total of seven human rabies cases and 437 animal rabies cases Tel: +82-54-912-0785, Fax: +82-54-912-0812 in five different species were reported. An increase in the distribution of bait vaccine seemed E-mail: [email protected] to be related to a dramatic decrease in rabies prevalence in endemic rabies regions. Two Korean provinces and the capital city, Seoul, were involved in rabies outbreaks. Korean rabies No potential conflict of interest relevant to this article was reported. strains are most closely related to the eastern Chinese strain belonging to the Arctic-like lin- eage. The yearly seropositive rates ranged from 50.4% to 81.2% in dogs and from 25% to 60.5% The authors thank all the people who were in charge of diagnosis and prevention at APQA and in cattle residing in endemic rabies regions. the local Veterinary Service Laboratories. This Conclusion: This study indicates that national preventive measures, including mass vaccina- work was supported financially by a grant (2016- tion and distribution of bait vaccines, have contributed to a substantial decrease in the number 269) from Korea Institute of Planning & Evaluation for Technology (IPET), Ministry of Agriculture, of rabies cases in Korea. Food and Rural Affairs (MAFRA), Republic of Korea. Keywords: Epidemiology, Rabies, Disease eradication, Korea Introduction Rabies is a fatal zoonotic disease caused by the rabies virus (RABV), which belongs to the Lyssavirus genus of the Rhabdoviridae family [1,2]. Once the clinical symptoms of rabies develop, death occurs in 100% of infected individuals. Although rabies is known K O R E A N V A C C I N E to be a preventable viral disease through vaccination, it occurs in more than 150 coun- S O C I E T Y tries. Recently, two Asian countries, Malaysia and Taiwan, lost their status as rabies-free due to outbreaks in dogs [3]. © Korean Vaccine Society. This is an Open Access article distributed under the Over 95% of human rabies cases are closely related to canine rabies, and animal ra- terms of the Creative Commons Attribution Non-Com- mercial License (http://creativecommons.org/licenses/ bies originates from many natural reservoirs [4]. Rabies is transmitted through the bites by-nc/4.0) which permits unrestricted non-commercial of several species of animal, including dogs, bats, raccoon dogs, wolves, and mongoos- use,K Odistribution,R E andA reproductionN in any medium, pro- vided the original work is properly cited. es; the source varies by country [5]. Recent animal rabies cases in Taiwan were related V A C C I N E S O C I E T Y http://www.ecevr.org/ 111 K O R E A N V A C C I N E S O C I E T Y Dong-Kun Yang et al • Elimination of rabies in Korea to ferret badgers (Melogale moschata) and the rabies cases the Korea Centers for Disease Control and Prevention. We al- that have occurred in South Korea since 1993 have been as- so referred to epidemiological reports of rabies cases written sociated with raccoon dogs (Nyctereutes procyonoide) [6,7]. by local Veterinary Service Laboratories (VSLs), which con- Analyzing the spatial and chronological distribution of ra- tained details concerning the population affected, location, bies cases is critical to forecast its spread into nearby regions. time of onset, clinical findings, and suspected etiology. Data Animal rabies has distinct clinical signs, such as excessive sal- concerning the quantities of rabies vaccine and bait vaccine ivation and abnormal behavior, and reported animal rabies given were collected from the Planning and Implementation cases are useful with respect to implementation of preventive of Livestock Prevention Project. National data on raccoon dog activities to control the disease. Spatial models have been used population density between 2002 and 2015 were collected to forecast raccoon-related rabies emergencies [8], and an anal- from the National Institute of Environmental Research. ysis of human rabies cases in Chinas used spatial clustering [9]. Molecular epidemiological studies have contributed to a Diagnosis of rabies better understanding of the geographic relationships among Animals suspected of having rabies were examined at the AP- rabies outbreaks, and have been used to determine the sourc- QA or local VSLs, and the brains of the animals were removed. es of infections [10,11]. The nucleocapsid (N) gene and pro- To confirm a rabies diagnosis, a FAT was performed on the tein have been targets for the diagnosis of rabies via the fluo- brain samples of animals using the procedure described by rescent antibody test (FAT) and reverse transcriptase polyme- the OIE [14]. Briefly, thin, frozen sections of the hippocampus rase chain reaction, because the N gene is highly conserved were fixed on a slide with cold acetone (-20°C) for 20 minutes. and large amounts of the N protein are produced in the infect- The samples were subsequently reacted with a specific mono- ed brain [12]. In the past, sero-surveys were considered to be clonal antibody (MEDIAN diagnostics, Chuncheon, Korea) of little value for determining rabies epidemiology because against rabies and stained with fluorescent isothiocyanate rabies antibodies were detected on the verge of death [13]. conjugated goat-anti mouse IgG+IgM. The samples showing However, rabies sero-surveillance has been used to monitor specific fluorescence in the treated section of the hippocam- the immune status of dogs and cattle after vaccination. Ra- pus were diagnosed as positive. bies antibodies can be measured by several methods, includ- ing the rapid fluorescent focus inhibition test (RFFIT), fluores- Spatial analysis cent antibody virus neutralization (FAVN), and enzyme-linked The locations of rabies cases were depicted on a map. The lo- immunosorbent assays. Both the RFFIT and FAVN tests are cation of each outbreak site or farm was identified using data recognized as reference assays by the World Health Organi- from the KAHIS program (http://www.kahis.go.kr) and depict- zation (WHO) and the World Organization for Animal Health ed as colored areas using the Map Wizard for Excel (Tastech, (OIE). In South Korea, enhanced rabies eradication programs, Seoul, Korea). including mass vaccination and distribution of rabies bait vaccine in rabies endemic regions, have been implemented Phylogenetic analysis in an effort to eliminate rabies by 2020 in accordance with the For the analysis of nucleotide sequences coding the N gene recommendations of international organizations. In this study, of Korean RABV, a total of 61 RABV isolates containing 40 Ko- we analyzed the epidemiology of rabies in Korea and evalu- rean RABV isolates were obtained from GenBank. Phyloge- ated the preventive measures initiated by the Korean Veteri- netic trees were reconstructed on aligned nucleotide sequenc- nary Authority over a period of 23 years, from 1993 to 2016. es using CLUSTAL W. Bootstrap analysis was used to deter- mine the robustness of the phylogenetic tree with 1,000 repli- Materials and Methods cations performed using MEGA6 software. Graphical output was produced using TreeView software (ver. 1.6.1; http://ra- Collection of data na.lbl.gov/EisenSoftware.htm). Detailed data on all animal rabies cases that were reported to the Animal and Plant Quarantine Agency (APQA) of Korea Collection of sera and the serological assay between 1993 and 2016 were collected. Data concerning hu- A total of 14,344 serum samples were collected from dogs and man rabies cases during the same period were collected from cattle residing in 20 counties of two Korean provinces, and in 112 http://www.ecevr.org/ https://doi.org/10.7774/cevr.2017.6.2.111 Dong-Kun Yang et al • Elimination of rabies in Korea the capital city, Seoul. Samples were collected from nine coun- Yangju, Yangpyeong, and Yeoncheon), and one county (Eun- ties in Gangwon province (Cheorwon, Chuncheon, Goseong, pyeong) in Seoul. Depending on the year, an average of 40 Hongchong, Inje, Sokcho, Hwacheon, Yanggu, and Yangyang), and 20 samples from dogs and cattle, respectively, were col- eleven counties in Gyeonggi province (Dongducheon, Gapy- lected from 21 counties. The virus neutralizing antibody test eong, Gimpo, Goyang, Paju, Pocheon, Suwon, Whaseong, for dogs and cattle was performed using the FAVN test [15], 900 800 8 11 783 703 700 600 Nerve tissue vaccine 502 (1945-1959) 500 Flury vaccine ERA vaccine V-RG bait vaccine (1960-1980) (1981-2016) (2000-2016) 400 382 300 242 No.