Passive Surveillance of SARS-CoV-2 in Adult Blacklegged Ticks (Ixodes scapularis) from Northeast Pennsylvania

Monitoring the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wildlife is vital to public health. White-tailed deer (Odocoileus virginianus) in the United States have tested positive for SARS-CoV-2, and their interactions with blacklegged ticks (Ixodes scapularis) raise the question of whether or not these ticks also carry SARS-CoV-2. In this study, 449 blacklegged ticks from Northeast Pennsylvania were collected in the fall of 2022 and tested via RT-qPCR for the presence of SARS-CoV-2. Fourteen ticks were amplified with late quantification cycles (Cq) using primers from two nucleocapsid genes (N1 and N2) via TaqMan assays. Three of these samples were amplified on a SYBR green assay during secondary testing. However, melt curve and gel electrophoresis analysis verified negative results for these three samples. Genetic sequencing was performed on one of the three samples to look for potential cross-reactions causing the amplification observed. However, no significant match was found in the NCBI database. Although all 449 blacklegged ticks were negative for SARS-CoV-2, I. scapularis should continue to be tested for COVID-19. If blacklegged ticks test positive for COVID-19 in the future, research should focus on determining the stability of SARS-CoV-2 with the tick vector and the potential for transmission through tick bites.

Surge in Anaplasmosis Cases in Maine, USA, 2013-2017

Incidence of human granulocytic anaplasmosis is rising in Maine, USA. This increase may be explained in part by adoption of tick panels as a frequent diagnostic test in persons with febrile illness and in part by range expansion of Ixodes scapularis ticks and zoonotic amplification of Anaplasma phagocytophilum.

A comparative evaluation of northern and southern Ixodes scapularis questing height and hiding behaviour in the USA

Ticks display a distinct type of host-seeking behaviour called questing. It has been proposed that the questing behaviour of Ixodes scapularis explains the geographic variation in Lyme disease (LD) risk in the eastern USA because the northern population has been shown to quest more often than the southern population. The height at which questing occurs is variable and this study aimed to characterize questing height for I. scapularis. Ticks were collected from a northern and southern state (i.e. Maryland and Texas) and bioassays were conducted. We report that nymphs from Texas quested at lower heights compared to nymphs from Maryland. In addition, only Texas nymphs exhibited a behaviour we call 'hiding behaviour'. These results may reflect the different composition of hosts between these two areas as the south has a higher abundance of lizards. In contrast, there was no significant difference in questing height between Maryland adults and Texas adults which was to be expected since adults are feeding on white-tailed deer in both locations. If all southern I. scapularis nymphs are questing at lower heights, this might make them less likely to come into contact with humans and this may be contributing to the geographical difference in LD prevalence.

Clinical and Laboratory Effects of Doxycycline and Prednisolone in Ixodes scapularis-Exposed Dogs With Chronic Anaplasma phagocytophilum Infection

Persistent infection of Anaplasma phagocytophilum (AP) after treatment and immunosuppression has not been studied in dogs infected with AP after Ixodes scapularis infestation. This descriptive pilot study evaluated 6 laboratory-reared beagles that were persistently positive for AP antibodies after infestation with wild-caught I. scapularis. After 20 weeks, 3 of 6 dogs were administered doxycycline orally for 28 days, and all 6 dogs were then administered prednisolone at 2.2 mg/kg orally for 14 days. Blood was collected from all 6 dogs and evaluated by complete blood count, AP antibodies, and AP DNA at the beginning of the study and on Week 24 through Week 28. Blood was collected from 5 of the dogs on Week 48. No dogs developed recognizable clinical signs of illness or clinically relevant complete blood count abnormalities. During Week 26 through Week 28, all 6 dogs were negative for AP DNA. On Week 48, the 2 doxycycline treated dogs available for testing were negative for AP DNA and antibodies; the 3 untreated dogs were negative for AP DNA but positive for AP antibodies. In this model, the prednisolone protocol used did not activate AP in dogs with chronic, vector-induced infection. Since PCR evidence of AP infection resolved in both groups of dogs, the effect doxycycline had in eliminating AP infection from I. scapularis-exposed dogs will require further study.

Insights into the development of Ixodes scapularis: a resource for research on a medically important tick species

Ticks (Acari: Ixodida) are arthropod ectoparasites dependent on a bloodmeal from a vertebrate host at each developmental stage for completion of their life cycle. This tick feeding cycle impacts animal health by causing damage to hides, secondary infections, immune reactions and diseases caused by transmission of pathogens. The genus Ixodes includes several medically important species that vector diseases, including granulocytic anaplasmosis and Lyme disease. I. scapularis, commonly called the black-legged or deer tick, is a medically-important tick species in North America and therefore was the first tick genome to be sequenced, thus serving as an important resource for tick research. This Primer focuses on the normal developmental cycle and laboratory rearing of I. scapularis. Definition of normal morphology, along with a consistent source of laboratory-reared I. scapularis, are fundamental for all aspects of future research, especially the effects of genetic manipulation and the evaluation of tick vaccine efficacy. Recent research important for the advancement of tick research, namely the development of tick cell culture systems for study of ticks and tick-borne pathogens, RNA interference for genetic manipulation of ticks and discovery of candidate antigens for development of tick vaccines, are briefly presented along with areas to target for future research.

Human babesiosis, Maine, USA, 1995-2011

We observed an increase in the ratio of pathogenic Babesia microti to B. odocoilei in adult Ixodes scapularis ticks in Maine. Risk for babesiosis was associated with adult tick abundance, Borrelia burgdorferi infection prevalence, and Lyme disease incidence. Our findings may help track risk and increase the focus on blood supply screening.