Abstract and Introduction
Introduction
Haemaphysalis longicornis is a tick indigenous to eastern Asia and an important vector of human and animal disease agents, resulting in such outcomes as human hemorrhagic fever and reduction of production in dairy cattle by 25%. H. longicornis was discovered on a sheep in New Jersey in August 2017.[1] This was the first detection in the United States outside of quarantine. In the spring of 2018, the tick was again detected at the index site, and later, in other counties in New Jersey, in seven other states in the eastern United States, and in Arkansas. The hosts included six species of domestic animals, six species of wildlife, and humans. To forestall adverse consequences in humans, pets, livestock, and wildlife, several critical actions are indicated, including expanded surveillance to determine the evolving distribution of H. longicornis, detection of pathogens that H. longicornis currently harbors, determination of the capacity of H. longicornis to serve as a vector for a range of potential pathogens, and evaluation of effective agents and methods for the control of H. longicornis.
H. longicornis is native to eastern China, Japan, the Russian Far East, and Korea. It is an introduced, and now established, exotic species in Australia, New Zealand, and several island nations in the western Pacific Region. Where this tick exists, it is an important vector of human and animal disease agents. In China and Japan, it transmits the severe fever with thrombocytopenia syndrome virus (SFTSV), which causes a human hemorrhagic fever,[2] and Rickettsia japonica, which causes Japanese spotted fever.[3] Studies in Asia identified ticks infected with various species of Anaplasma, Babesia, Borrelia, Ehrlichia, and Rickettsia, and all of these pathogen groups circulate zoonotically in the United States.[4,5] In addition, parthenogenetic reproduction, a biologic characteristic of this species, allows a single introduced female tick to generate progeny without mating, thus resulting in massive host infestations. In some regions of New Zealand and Australia, this tick can reduce production in dairy cattle by 25%.[6] Before 2017, H. longicornis ticks were intercepted at U.S. ports of entry at least 15 times on imported animals and materials (James W. Mertins, U.S. Department of Agriculture [USDA], personal communication).
The USDA Animal and Plant Inspection Service coordinated cooperative efforts through telephone conference calls with various local, state, and federal agricultural and public health agencies. Through these efforts, enhanced vector and animal surveillance were implemented to detect additional tick infestations. Suspect archival specimens that were available among previously collected ticks were also examined. Ticks were identified definitively by morphology at the USDA National Veterinary Services Laboratories or by DNA sequence analysis (molecular barcoding) at Rutgers University Center for Vector Biology, Monmouth County (New Jersey) Mosquito Control Division; College of Veterinary Medicine, University of Georgia; and Center for Veterinary Health Sciences, Oklahoma State University. By definition, a "report" is any new morphologic or molecular identification of H. longicornis ticks with a new county or host species from that county, identified from August 2017 through September 2018. Subsequent repeat collections are not reported here.
From August 2017 through September 2018, vector and animal surveillance efforts resulted in 53 reports of H. longicornis in the United States, including 38 (72%) from animal species (23 [61%] from domestic animals, 13 [34%] from wildlife, and two [5%] from humans), and 15 (28%) from environmental sampling of grass or other vegetation using cloth drags or flags* or carbon dioxide–baited tick traps.† With the exception of one report from Arkansas, the remaining reports of positively identified ticks are from eight eastern states: New Jersey (16; 30%), Virginia (15; 28%), West Virginia (11; 21%), New York (three; 6%), North Carolina (three; 6%), Pennsylvania (two; 4%), Connecticut (one; 2%), and Maryland (one; 2%) (Figure). Among the 546 counties or county equivalents in the nine states, ticks were reported from 45 (8%) counties (1.4% of all 3,109 U.S. counties and county equivalents) (Table 1). Excluding 15 reports of positive environmental sampling using flagging, dragging, or carbon dioxide traps, the remaining 38 reports reflect collection of ticks from infested host species (Table 2). Surveillance efforts did not include testing the ticks or hosts for pathogens. No cases of illness in humans or other species were reported. Concurrent reexamination of archived historical samples showed that invasion occurred years earlier. Most importantly, ticks collected from a deer in West Virginia in 2010 and a dog in New Jersey in 2013 were retrospectively identified as H. longicornis.
Figure.
Counties and county equivalents* where Haemaphysalis longicornis has been reported (N = 45) — United States, August 2017–September 2018
* Benton County, Arkansas; Fairfield County, Connecticut; Washington County, Maryland; Bergen, Hunterdon, Mercer, Middlesex, Monmouth, Somerset, and Union Counties, New Jersey; Davidson, Polk, and Rutherford Counties, North Carolina; Richmond, Rockland, and Westchester Counties, New York; Bucks and Centre Counties, Pennsylvania; Albemarle, Augusta, Carroll, Fairfax, Giles, Grayson, Louisa, Page, Pulaski, Rockbridge, Russell, Scott, Smyth, Staunton City, Warren, and Wythe Counties, Virginia; Cabell, Hardy, Lincoln, Mason, Marion, Monroe, Putnam, Ritchie, Taylor, Tyler, Upshur Counties, West Virginia.
Morbidity and Mortality Weekly Report. 2018;67(47):1310-1313. © 2018 Centers for Disease Control and Prevention (CDC)
