Distribution of Haemaphysalis longicornis and associated pathogens: analysis of pooled data from a China field survey and global published data

Abstract

Background Haemaphysalis longicornis, a vector of various pathogens with medical and veterinary importance, is native to eastern Asia, and recently reached the USA as an emerging disease threat. In this study, we aimed to identify the geographical distribution, hosts, and associated pathogens of H longicornis.Methods Data were collected from multiple sources, including a field survey, reference book, literature review, and related websites. The thematic maps showing geographical distribution of H longicornis and associated pathogens were produced by ArcGIS. Hosts of H longicornis and positive rates for H longicornis-associated pathogens were estimated by meta-analysis. Ecological niche modelling was used to predict potential global distribution of H longicornis.Findings H longicornis was found to be present in ten countries, predominantly in eastern Asia, the USA, Australia, and New Zealand. The tick was known to feed on a variety of domestic and wild animals, and humans. At least 30 human pathogens were associated with H longicornis, including seven species of spotted fever group rickettsiae, seven species in the family of Anaplasmataceae, four genospecies in the complex Borrelia burgdorferi sensu lato, two Babesia species, six species of virus, and Francisella, Bartonella, Coxiella, and Toxoplasma, which were mainly reported in eastern Asia. The predictive modelling revealed that H longicornis might affect more extensive regions, including Europe, South America, and Africa, where the tick has never been recorded before.Interpretation H longicornis is relatively common in the world, and is associated with various human and animal pathogens. Authorities and health-care workers should be aware of the threat of the tick species to public health and veterinary medicine. Surveillance and further investigations should be enhanced globally.

Comparison of Habitat Suitability Models for Haemaphysalis longicornis Neumann in North America to Determine Its Potential Geographic Range

“…The establishment and potential expansion of H. longicornis in North America has been of public health and veterinary concern, particularly in the United States and Canada. Globally, this tick species is associated with at least 59 pathogens, of which 30 are potentially pathogenic to humans [45]. The most noted human pathogen transmitted by the H. longicornis in its native range in East Asia is the SFTSV [4].…”

“…Currently, all published models of H. longicornis distribution use climatic variables to predict distribution [27][28][29]45]. Ecological zones have also been included as these can represent a complex of interacting abiotic and biotic variables [28].…”

“…The wide host range of H. longicornis may facilitate dispersion over short and long distances. Globally, 77 species of animals are hosts for this tick species [45]. In the United States, the H. longicornis has been isolated from 21 species of domestic and wild animals and also from humans [19].…”

“…In the United States, the H. longicornis has been isolated from 21 species of domestic and wild animals and also from humans [19]. Migratory birds might play an important role in the dispersal of this tick to a new area [29,45]. Further, the parthenogenetic ability of H. longicornis is particularly concerning in the context of its potential expansion [29].…”

“…H. longicornis tolerates a wide range of temperatures (−2 to 40 • C), but the warm and moist temperate conditions are known to be preferred [3]. Humidity is the limiting factor for the establishment of H. longicornis populations, as the threshold for survival and host-seeking activity is 85% relative humidity [3,45]. In our models (models 2 and 6), the most important environmental variables influencing the distribution of H. longicornis were bio 1 (annual mean temperature) and GEZ for model 2, and GEZ and bio 11 (mean temperature of coldest quarter) for model 6.…”