Richard G. Robbins

Importation of exotic ticks and tick-borne spotted fever group rickettsiae into the United States by migrating songbirds

Birds are capable of carrying ticks and, consequently, tick-transmitted microorganisms over long distances and across geographical barriers such as oceans and deserts. Ticks are hosts for several species of spotted fever group rickettsiae (SFGR), which can be transmitted to vertebrates during blood meals. In this study, the prevalence of this group of rickettsiae was examined in ticks infesting migratory songbirds by using polymerase chain reaction (PCR). During the 2009 and 2010 spring migration season, 2064 northward-migrating passerine songbirds were examined for ticks at Johnson Bayou, Louisiana. A total of 91 ticks was removed from 35 individual songbirds for tick species identification and spotted fever group rickettsia detection. Ticks were identified as Haemaphysalis juxtakochi (n=38, 42%), Amblyomma longirostre (n=22, 24%), Amblyomma nodosum (n=17, 19%), Amblyomma calcaratum (n=11, 12%), Amblyomma maculatum (n=2, 2%), and Haemaphysalis leporispalustris (n=1, 1%) by comparing their 12S rDNA gene sequence to homologous sequences in GenBank. Most of the identified ticks were exotic species originating outside of the United States. The phylogenetic analysis of the 71 ompA gene sequences of the rickettsial strains detected in the ticks revealed the occurrence of 6 distinct rickettsial genotypes. Two genotypes (corresponding to a total of 28 samples) were included in the Candidatus Rickettsia amblyommii clade (less than 1% divergence), 2 of them (corresponding to a total of 14 samples) clustered with Rickettsia sp. Argentina with less than 0.2% sequence divergence, and 2 of them (corresponding to a total of 27 samples), although closely related to the R. parkeri-R. africae lineage (2.50-3.41% divergence), exhibited sufficient genetic divergence from its members to possibly constitute a new rickettsial genotype. Overall, there does not seem to be a specific relationship between exotic tick species, the rickettsiae they harbor, or the reservoir competence of the corresponding bird species.

Host–Parasite Associations in Small Mammal Communities in Semiarid Savanna Ecosystems of East Africa

Abstract Despite the established importance of rodents as reservoirs of vector-borne zoonoses in East Africa, there is relatively limited information regarding the infestation parameters and host associations of ectoparasites that vector many such pathogens among small mammals in this region. Between 2009 and 2013, small mammals were live-trapped in the semiarid savanna of Kenya. A subset of these individual hosts, including 20 distinct host taxa, was examined for ectoparasites, which were identified to species. Species of fleas, ticks, mites, and sucking lice were recorded. Based on these data, we calculated host-specific infestation parameters, documented host preferences among ectoparasites, conducted a rarefaction analysis and extrapolation to determine if ectoparasites were adequately sampled, and assessed nestedness for fleas to understand how pathogens might spread in this system. We found that the flea community structure was significantly nested. Understanding the ectoparasite network structure may have significant human relevance, as at least seven of the ectoparasite species collected are known vectors of pathogens of medical importance in the region, including Yersinia pestis, Rickettsia spp., and Theileria parva, the causative agents of plague, spotted fevers and other rickettsial illnesses in humans, and theileriosis, respectively.

First survey of the hard tick (Acari: Ixodidae) fauna of Nakai District, Khammouane Province, Laos, and an updated checklist of the ticks of Laos

Abstract From 2012 to 2014, tick collections for tick and tick-borne pathogen surveillance were carried out in two areas of Nakai District, Khammouane Province, Laos: the Watershed Management and Protection Authority (WMPA) area and Phou Hin Poun National Protected Area (PHP NPA). Throughout Laos, ticks and tick-associated pathogens are poorly known. Fifteen thousand and seventy-three ticks representing larval (60.72%), nymphal (37.86%) and adult (1.42%) life stages were collected. Five genera comprising at least 11 species, including three suspected species that could not be readily determined, were identified from 215 adult specimens: Amblyomma testudinarium Koch (10; 4.65%), Dermacentor auratus Supino (17; 7.91%), D. steini (Schulze) (7; 3.26%), Haemaphysalis colasbelcouri (Santos Dias) (1; 0.47%), H. hystricis Supino (59; 27.44%), H. sp. near aborensis Warburton (91; 42.33%), H. sp. near darjeeling Hoogstraal and Dhanda (5; 2.33%), H. sp. near lagrangei Larrousse (3; 1.4%), H. spp. (16; 7.45%), Rhipicephalus haemaphysaloides (Supino) (5; 2.33%), and R. (Boophilus) microplus (Canestrini) (1; 0.47%). These collections, together with the literature to date, provide evidence for the occurrence of at least 22 ixodid tick species, representing six genera, in Laos. Here we present new records for at least four tick species from WMPA area, Nakai District, Khammouane Province, where tick-borne pathogens may circulate. These preliminary results should serve as a framework for further molecular investigations of putative tick vectors and their pathogens in Laos.

Ticks Feeding on Humans

With the exception of ticks in the genera Anomalohimalaya, Cosmiomma, Margaropus, Rhipicentor and the two fossil genera, at least one member of each ixodid genus has been observed feeding on humans. Table 1 below shows the numbers and percentages of species in each genus that have been found feeding on humans alongside the corresponding numbers and percentages of species in all genera of the Ixodidae. Over a third (38 % or 267 species) feed on humans, although many of these are not known to transmit pathogens. The genera Rhipicephalus, Dermacentor and Hyalomma are particularly important because more than 50 % of their members have been found attached to humans. The maximum percentages are Hyalomma (18 taxa or 67 %) followed by Dermacentor (23 species or 66 %). However, in absolute terms the genus Ixodes contributes the highest number of species (63 species, 26 % of the total), followed by Amblyomma (58 species, 45 % of the total), Haemaphysalis (56 species, 33 % of the total) and Rhipicephalus (46 species, 55 % of the total). Over the last two decades, the known number and significance of tick-borne diseases have markedly increased. This tendency is likely to continue, and ticks will remain a group of interest to researchers as more species are collected from humans and consequently viewed as potential disease vectors.

New records for Amblyomma rotundatum Koch (Acari: Ixodidae) from the cane toad, Rhinella marina L. in Florida, with notes on identification of the nymphs

Abstract Sixty-one cane toads, R. marina, were captured by hand at four locations in Dade County, Florida, on May 9 (n=32) and September 3 (n=29) 2014. Toads were examined for ectoparasites and any ticks seen were removed and placed in 95% ethanol. Of the 61 toads, 8 (13.1%) collected in two separate locations were found with attached Amblyomma sp. A total of 31 ticks (12 nymphs, 19 larvae) were removed from the toads, ranging from 1–13 specimens collected per toad. In the case of 3 nymphal specimens found in our study, precise identification could not be made by conventional light microscopy due to obscured or unclear characters; therefore, scanning electron microscopy (SEM) was performed on these specimens to aid in identification. SEM analysis revealed an internal spur, albeit tiny, on coxa II of the specimens in question, but no spur was seen on coxa III. Published key characters for A. rotundatum state that, “a small internal spur is present on each of coxa II and III.” Despite this published description, we concluded that the presence of a small spur on coxa II in this case was diagnostic for A. rotundatum.

New Missouri County Records and Review of the Distribution and Disease Vector Potential of Ornithodoros Kelleyi (Arachnida: Ixodida: Argasidae) and Cimex Adjunctus (Insecta: Hemiptera: Cimicidae)

Abstract. n The bat tick Ornithodoros kelleyi Cooley and Kohls (Arachnida: Ixodida: Argasidae) and eastern bat bug Cimex adjunctus Barber (Insecta: Hemiptera: Cimicidae) were collected from houses in Greene County, Missouri, that were previously infested by bats. Additional specimens of C. adjunctus were taken from a live big brown bat (Eptesicus fuscus (Palisot de Beauvois)) in Greene County and an evening bat (Nycticeius humeralis (Rafinesque)) in Webster County, Missouri. These records constitute only the third report of each species from the state, and the first from those counties. Distributional and host data for both species are summarized and presented. Distribution, feeding habits, and limited association with human habitations confer a low disease vector potential on both ectoparasites.

Ornithodoros sawaii (Ixodida: Argasidae) Larvae Collected from Hydrobates monorhis on Sogugul and Gaerin Islands, Jeollanam-do (Province), Republic of Korea.

The 65th Medical Brigade and Public Health Command District-Korea, in collaboration with the Migratory Bird Research Center, National Park Research Institute, conducted migratory bird tick surveillance at Sogugul and Gaerin Islands (small rocky bird nesting sites), Jeollanam-do (Province), Republic of Korea (ROK), on 30 July and 1 August 2009. Breeding seabirds captured by hands in their nesting burrows were banded, identified to species, and carefully examined for ticks during the nesting season. A total of 9 Ornithodoros sawaii larvae were removed from 4 adult Hydrobates monorhis (Swinhoe’s storm petrel). The identification of the larvae of O. sawaii collected from migratory seabirds were molecularly confirmed using mitochondrial 16S rDNA primer sets.

Type Depository Acronyms

Type depositories are included for all taxa and are referenced using the acronyms listed below. Some collections in the USA have been merged and new names have been given to them. For example, the former Rocky Mountain Laboratories and Harry Hoogstraal collections are now in the U.S. National Tick Collection. Throughout, we have used the current acronym, even when the original description states otherwise.

General Comment and Remarks on an Invalid Name

The genus Dermacentor is under revision by one of us (DAA). Therefore, several changes in the taxonomy and nomenclature of this genus are expected in the near future.

General Comment and Remarks on Some Invalid Names

Romero-Castanon et al. (2008) record the presence of Hyalomma sp. in the Neotropical Zoogeographic Region and, by implication, the Americas. However, their paper contains gross errors in literature interpretation (see the remarks on Amblyomma cajennense in our Amblyomma chapter for just one example), and we consider their diagnosis erroneous.