Gulf Coasts Ticks Infected with Rickettsia parkerii Established in NYC
In a recent New York City (NYC) study, researchers investigated habitat associations and pathogen status of Gulf coast ticks (Amblyomma maculatum). NYC is a newly expanded distribution range for this species.
Investigators collected 88 ticks from two parks on Staten Island (NYC) and compared findings of ticks collected from similar habitats in Brooklyn from April 30–September 1. They then tested 77 ticks for pathogens.
Gulf coast tick collections from Freshkills and Brookfield parks on Staten Island, NYC, included both adult and immature ticks. Ticks were found in both native and invasive grass habitats. No Gulf coast ticks were collected in Brooklyn. Of the ticks tested, 52.6% were found to be infected with Rickettsia parkeri—the etiological agent of R. parkeri rickettsiosis.
Researchers caution that this high rate of infection in such a densely populated urban center is a concern to public health and that the medical community needs to be aware of both the presence of this vector as well as the symptoms associated with R. parkerii infections.
Other LDA articles on Gulf coast ticks can be found here
Anaplasma phagocytophilum Human Agent Variant Detected in Asian Longhorned Ticks
In a newly published US study, Anaplasma phagocytophilum–human agent variant has been detected for the first time in the highly invasive Asian longhorned tick (Haemaphysalis longicornis). Active tick surveillance was conducted throughout Pennsylvania during the time period of May 1st through September 6th, 2019. Researchers tested 265 ticks for rickettsial pathogens through PCR testing and 1.5% of these ticks were positive for A. phagocytophilum. Two were confirmed positive as A. phagocytophilum–human agent variant through sequence analysis of the 16S rRNA gene.
Additional LDA articles on Asian longhorned tick pathogens can be found here
Babesiosis: A Global Review
This review summarizes the health burden of human babesiosis emerging on a global scale. Authors discuss tools used to monitor the frequency and location of disease as well as demographics, modes of transmission and the location of human babesiosis. Authors further describe the causative Babesia spp. in North and South America, Europe, Asia, Africa, and Australia and present the primary symptomology and clinical features associated with infections.
The disease burden of human babesiosis is especially impactful on immunocompromised patients and the elderly population. Authors state that case numbers are greatly underestimated and are likely to increase, and they suggest that there is a need for improved surveillance, development of new antibiotics, supportive therapies, and a vaccine to limit the impact of the disease worldwide.
The Journal of Medical Entomology has published a recent article regarding utilization of integrated tick management (ITM). Researchers studied the effects of “configuration of bait box deployment” on the reduction of tick burden in a suburban/rural landscape. Researchers additionally investigated bait consumption and white-footed mouse (P. leucopus) abundances as a measure of the usage and effectiveness of bait boxes.
Bait boxes were placed in both grid and perimeter layouts on nine properties within each of six neighborhoods throughout Guilford, Connecticut. These properties consisted of a matrix of forested, residential, preserved open space and some agricultural lands. The investigators then analyzed multiple factors as potential predictors for reduction in tick burdens using a “backward stepwise selection procedure.”
Results of the study show that the perimeter layout was the more effective placement strategy for bait boxes. They also found that white-footed mouse abundance was a significant predictor of reduction of tick burden, but that bait consumption was not. The findings of this study support the recommended perimeter placement layout for bait boxes, and provides insight into effective utilization in areas of high white-footed mouse abundance.
Vector control professionals, homeowners and other stakeholders can utilize the results of this study to make informed decisions regarding bait box placement on properties to exert the greatest impact on blacklegged tick reduction and their associated pathogens using ITM strategies.
More LDA articles on Integrative Tick Management here
Arkansas Community Scientist Study on Tick Distribution and Ehrlichia & Rickettsia
Dowling, A., et al., published a report in Journal of Medical Entomology with the results of a cooperative effort to survey ticks throughout Arkansas to better understand the heavy impacts of TBDs such as spotted fever rickettsiosis, and ehrlichiosis in the mid-south. Logistical and financial barriers, and an expanding geographic area of concern, prompted researchers to collaborate with members of the public to gather data on human disease-causing pathogens carried by ticks. The 20-month period study focused on ticks that encounter humans most often. Arkansans contributed 9,002 ticks collected from 71 of the state’s 75 counties.
The Amblyomma americanum (lone star tick) was the most commonly found– 76% of all ticks in the study. Of the ~ 6,000 screened ticks, the prevalence rate was 37.4% for Rickettsia (SFGR-spotted fever group Rickettsia) and 5.1% for Ehrlichia. One hundred forty-five ticks (2.5%), were simultaneously infected with SFGR and Ehrlichia. During the study period, Arkansas Department of Health reported 2,281 spotted fever and 380 ehrlichiosis cases.
Dermacentor variabilis (American dog tick) and Amblyomma maculatum (Gulf Coast tick) were not the most frequently submitted ticks, nor did they have the highest occurrence of SFGR. Therefore, the researchers speculate that other tick species seem to play the primary role in infecting humans with SFGR.
Tick Sugar Influence on Cell Wall of Borrelia Spirochetes
Nature Microbiology recently published an article where researchers identified a sugar that influences cell wall function in Borrelia spirochetes. Authors state that Borrelia burgdorferi bacteria produces glycan chains in the cell wall where MurNAc is occasionally replaced with an unknown sugar. Investigators identified that B. burgdorferi produces glycans that contain GlcNAc–GlcNAc. Chitobiose is the unusual disaccharide, or sugar, identified in the cell wall of Borrelia bacteria.
Mutant bacteria, bacteria that require a particular additional nutrient which the normal strain does not, have altered morphology, reduced motility, and cell envelope defects that researchers suspect result from producing peptidoglycan that is stiffer than that in wild-type bacteria.
Virginia Tech researchers discovered that the bacterium that causes Lyme disease has a highly unusual modification in its protective molecular bag—its peptidoglycan, which is common to all bacteria. Researchers conducted LCMS, liquid chromatography coupled with mass spectroscopy to determine that chitobiose was the actual sugar. They also conducted Nuclear Magnetic Resonance and metabolic labeling studies with C13 labeled sugars to confirm this finding. They additionally determined why this modification is found in Borrelia—it allows for elasticity which supports effective motility of the bacteria to move through tissue and cartilage. Without this modification, motility is impeded.
The change in the Borrelia bacterium is unprecedented—it’s an unusual sugar modification that is not known to occur in any other organism. One way the bacterium gets this sugar modification is from ticks. This happens by absorbing a carbohydrate unique to ticks. The alteration is specific to ticks and allows the bacterium to better move and be more likely to cause disease in hosts.
Researchers provide evidence for this model, demonstrating that bacteria that are unable to bring in chitobiose to the cells have reduced amounts of peptidoglycan, as well as altered peptidoglycan composition, which results in abnormalities in bacterial cell form and structure.
The significance of these findings is that disrupting the balance between flagellar motion and peptidoglycan structure impairs motility, which hinders bacterial movement. This finding could potentially shed light on understanding what causes symptoms and illness in humans, as well as identifying potential diagnostic and treatment strategies that target Borrelia spirochetes.
Read the full text Nature Microbiology article here
In a recent article, Johns Hopkins presents its newly developed tool, the Lyme and Tickborne Disease (TBD) Dashboard which tracks tickborne diseases at a global scale and displays maps and spatial data sets utilizing unique geographic context and includes a search function to find out what the incidence is in your US county.
This initiative was led by the Johns Hopkins Spatial Science for Public Health Center, in collaboration with the Johns Hopkins Medicine Lyme Disease Research Center and the Johns Hopkins Lyme and Tickborne Diseases Research and Education Institute.
The dashboard was primarily designed for researchers. However, this tool is both accessible and useful for use in the public health sector, policymakers, advocacy groups, and the general public.
The article describes how this novel tool can be used to raise awareness of TBDs and encourage both research and collaboration in science representing a One Health approach. Authors describe the experience of Johns Hopkins developers in designing and implementing the dashboard modeled after their COVID-19 dashboard and the main features of the Lyme & TBD dashboard. The article also presents discussion of the current limitations and future directions of this tool.
Read additional LDA articles on Lyme & TBD distribution here
Study Indicates Shrews as a Reservoir for Powassan Virus
Heidi K. Goethert, et al., published, “Incrimination of shrews as a reservoir for Powassan virus,” in Communications Biology. The study examines Powassan virus lineage 2 (deer tick virus), and the growing threat the pathogen poses to American public health. Powassan virus is known to cause severe neurologic disease although its life cycle in nature is poorly understood.
The researchers used a host-specific real-time PCR to investigate if white-footed mice–the primary eastern U.S. reservoir of Lyme disease– are also the reservoir for deer tick virus.
Of 20 virus-infected black-legged ticks, 65% fed on shrews and none fed on mice. This percentage of ticks feeding on shrews was clearly associated with the incidence of the deer tick virus infection, although not the Lyme disease agent. One shrew had viral DNA in its brain.
Based on the findings, the research team proposed that shrews are a probable reservoir host for deer tick virus and that evaluation of host blood meals can provide clear evidence to implicate reservoir hosts, thus providing a better understanding of the ecology of tick-borne infections.
In a recent article published by the Centers for Disease Control (CDC), authors detected Borrelia miyamotoi in ticks from 19 states in the US. Investigators tested 39,198 ticks for B. miyamotoi that were submitted to the public tick testing program at the University of Massachusetts during May 2013–December 2019. All ticks tested were found on humans.
In Oregon and California, B. miyamotoi was found in Ixodes pacificus ticks. Throughout the Northeastern and Midwestern US, B. miyamotoi was detected in Ixodes scapularis ticks. No ticks carrying B. miyamotoi were detected south of Virginia. It was also found that Lyme disease bacterium was 19 times more prevalent than B. miyamotoi in the I. scapularis ticks. Of note, almost 60% of B. miyamotoi–positive I. scapularis ticks had concurrent infections.
Ehrlichiosis and Anaplasmosis Transmitted Through Blood Transfusions and Organ Transplants
A recent study published in the CDC’s Emerging Infectious Diseases journal finds ehrlichiosis and anaplasmosis can also be transmitted through blood transfusions or organ transplants. The article states, “Since 2000, ehrlichiosis and anaplasmosis cases in the United States have increased substantially, resulting in potential risk to transplant and transfusion recipients.”
The investigating clinicians reviewed cases of ehrlichiosis and anaplasmosis among blood transfusion and solid organ transplant recipients in the U.S. from peer-reviewed literature and CDC studies. They identified 132 cases during 1997–2020, including 12 transfusion-associated cases and 120 cases in transplant recipients. Eight of the cases were donor-derived, and illness occurred in 13 of the cases less than one year after transplant. Disease in the remaining 99 cases occurred within one year, or longer, after transplant, which suggests that donor-derived disease was unlikely. Sadly, severe illness or death were reported among 15 transfusion and transplant recipients (Sanjida J., et al.).
The study’s authors emphasize that clinicians should be on the alert for these potential infections among transfusion and transplant recipients to prevent serious complications or death by treating them promptly.