Publications by authors named "William L Nicholson"

Article Synopsis
  • The study investigated risk factors for spotted fever group rickettsioses (SFGR) in the Kilimanjaro Region, Tanzania, focusing on febrile patients from local hospitals between 2012 and 2014.
  • Of 1,190 participants, 54.6% had SFGR exposure, with 9.2% displaying acute SFGR; factors such as age, rural living, and temperature were significant in determining risk.
  • The findings highlight that children under 2 years, rural residents, and those in cooler areas may be at higher risk for SFGR, suggesting a need for targeted prevention strategies and additional research on tick exposure.
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We report a patient in North Carolina, USA, with Heartland virus infection whose diagnosis was complicated by previous Ehrlichia chaffeensis infection. We identified E. ewingii-infected and Bourbon virus-infected tick pools at the patient's residence.

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Rocky Mountain spotted fever (RMSF) is a severe tickborne disease that can reach epidemic proportions in communities with certain social and ecologic risk factors. In some areas, the case-fatality rate of brown dog tick-associated RMSF is up to 50%. Because of the spread of brown dog tick-associated RMSF in the southwestern United States and northern Mexico, the disease has the potential to emerge and become endemic in other communities that have large populations of free-roaming dogs, brown dog ticks, limited resources, and low provider awareness of the disease.

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Hard ticks (Acari: Ixodidae) have been historically identified by morphological methods which require highly specialized expertise and more recently by DNA-based molecular assays that involve high costs. Although both approaches provide complementary data for tick identification, each method has limitations which restrict their use on large-scale settings such as regional or national tick surveillance programs. To overcome those obstacles, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been introduced as a cost-efficient method for the identification of various organisms, as it balances performance, speed, and high data output.

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Bacterial zoonoses are established causes of severe febrile illness in East Africa. Within a fever etiology study, we applied a high-throughput 16S rRNA metagenomic assay validated for detecting bacterial zoonotic pathogens. We enrolled febrile patients admitted to 2 referral hospitals in Moshi, Tanzania, during September 2007-April 2009.

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Article Synopsis
  • The brown dog tick, Rhipicephalus sanguineus s.l., is a significant carrier of Rickettsia rickettsii, which causes Rocky Mountain spotted fever, prompting public health measures to control tick infestations around homes and on pets.
  • Current control strategies primarily rely on acaricides, particularly synthetic pyrethroids, but many ticks have developed resistance to these chemicals, complicating prevention efforts.
  • Researchers used advanced sequencing techniques to study genetic variations associated with acaricide resistance in different lineages of the tick, finding a specific genetic mutation tied to resistance that was commonly found in tropical lineage ticks across various locations in the US.
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The recovery of a Haemaphysalis longicornis Neumann (Acari: Ixodidae) tick from a dog in Benton County, Arkansas, in 2018 triggered a significant environmental sampling effort in Hobbs State Park Conservation Area. The objective of the investigation was to assess the tick population density and diversity, as well as identify potential tick-borne pathogens that could pose a risk to public health. During a week-long sampling period in August of 2018, a total of 6,154 ticks were collected, with the majority identified as Amblyomma americanum (L), (Acari: Ixodidae) commonly known as the lone star tick.

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Article Synopsis
  • The study focused on the prevalence of Q fever and rickettsioses in a pastoralist community in northern Tanzania, highlighting their commonality as causes of febrile illness.
  • Analysis involved 228 febrile patients, where significant serological evidence indicated high exposure rates to C. burnetii and SFG Rickettsia, with a notable prevalence of probable cases.
  • The research identified livestock slaughter as a significant risk factor, increasing the likelihood of acute Q fever and SFG rickettsioses among participants.
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Haemaphysalis longicornis (Neumann) is an invasive ixodid tick originating from eastern Asia which recently has become established in the United States. In its native range, this tick can transmit several pathogens to animals and humans, but little is known about its ability to acquire and transmit pathogens native to the United States. Geographic overlap with ticks such as Dermacentor variabilis (Say), a known vector of Rickettsia rickettsii, makes investigation into the interactions between H.

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Anaplasmosis is increasingly common in the United States, with cases being reported over an expanding geographic area. To monitor for changes in risk of human infection, the U.S.

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Article Synopsis
  • * Active surveillance in Pennsylvania identified and tested 265 H. longicornis ticks for pathogens from May to September 2019.
  • * Four ticks (1.5%) tested positive for Anaplasma phagocytophilum, marking the first detection of this human pathogenic strain in the tick species in the USA.
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Q fever and spotted fever group rickettsioses (SFGR) are common causes of severe febrile illness in northern Tanzania. Incidence estimates are needed to characterize the disease burden. Using hybrid surveillance-coupling case-finding at two referral hospitals and healthcare utilization data-we estimated the incidences of acute Q fever and SFGR in Moshi, Kilimanjaro, Tanzania, from 2007 to 2008 and from 2012 to 2014.

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Article Synopsis
  • - The Asian longhorned tick, originally from eastern Asia, was first detected in the USA in New Jersey and has since spread to several eastern states, including Arkansas and Missouri.
  • - This invasive tick species is known to carry diseases that affect both livestock and humans, which has led to increased survey efforts to monitor its spread.
  • - A tick drag in Greene County, Missouri, on June 9, 2021, resulted in the identification of two H. longicornis nymphs, marking the first report of this tick in both the state and county.
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We identified an established population of the Gulf Coast tick (Amblyomma maculatum Koch) infected with Rickettsia parkeri in Connecticut, representing the northernmost range limit of this medically relevant tick species. Our finding highlights the importance of tick surveillance and public health challenges posed by geographic expansion of tick vectors and their pathogens.

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Crimean-Congo hemorrhagic fever (CCHF), Q fever, and Lyme disease are endemic to southern Kazakhstan, but population-based serosurveys are lacking. We assessed risk factors and seroprevalence of these zoonoses and conducted surveys for CCHF-related knowledge, attitudes, and practices in the Zhambyl region of Kazakhstan. Weighted seroprevalence for CCHF among all participants was 1.

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Objective: Identifying febrile patients requiring antibacterial treatment is challenging, particularly in low-resource settings. In South-East Asia, C-reactive protein (CRP) has been demonstrated to be highly sensitive and moderately specific in detecting bacterial infections and to safely reduce unnecessary antibacterial prescriptions in primary care. As evidence is scant in sub-Saharan Africa, we assessed the sensitivity of CRP in identifying serious bacterial infections in Tanzania.

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Since its recent discovery, Bourbon virus has been isolated from a human and ticks. To assess exposure of potential vertebrate reservoirs, we assayed banked serum and plasma samples from wildlife and domestic animals in Missouri, USA, for Bourbon virus-neutralizing antibodies. We detected high seroprevalence in raccoons (50%) and white-tailed deer (86%).

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Portions of northern Mexico are experiencing a re-emergence of Rocky Mountain spotted fever (RMSF), a tickborne disease caused by Rickettsia rickettsii, a member of the spotted fever group of rickettsiae (SFGR). Infection with R. rickettsii can result in serious and life-threatening illness in people and dogs.

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In the United States, tick-borne diseases are increasing in incidence and cases are reported over an expanding geographical area. Avoiding tick bites is a key strategy in tick-borne disease prevention, and this requires current and accurate information on where humans are at risk for exposure to ticks. Based on a review of published literature and records in the U.

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Rocky Mountain spotted fever (RMSF) is a severe tick-borne rickettsial illness. In the south-western United States and Mexico, RMSF displays unique epidemiologic and ecologic characteristics, including Rhipicephalus sanguineus sensu lato (brown dog tick) as the primary vector. Expansion and spread of the disease from hyperendemic regions of Arizona or Mexico to new areas is a key public health concern.

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Article Synopsis
  • The American dog tick (Dermacentor variabilis) is a significant vector of Rickettsia bacteria, including the one that causes Rocky Mountain spotted fever (RMSF), particularly in North Carolina where tick-borne illnesses are prevalent.
  • Researchers collected ticks from 32 counties in North Carolina between 2009 and 2013 and found that about 50% of the ticks were infected with various Rickettsia species, including R. amblyommatis and R. rickettsii.
  • The study highlighted the importance of understanding the distribution of infected ticks, as this information helps assess public health risks related to tick-borne diseases in the region.
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Bourbon virus (BRBV) was first isolated in 2014 from a resident of Bourbon County, Kansas, USA, who died of the infection. In 2015, an ill Payne County, Oklahoma, resident tested positive for antibodies to BRBV, before fully recovering. We retrospectively tested for BRBV in 39,096 ticks from northwestern Missouri, located 240 km from Bourbon County, Kansas.

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In 1953, investigators at the Rocky Mountain Laboratories in Hamilton, MT, described the isolation of a spotted fever group (SFGR) species from ticks collected from black-tailed jackrabbits () in northern Nevada. Several decades later, investigators characterized this SFGR (designated the parumapertus agent) by using mouse serotyping methods and determined that it represented a distinct rickettsial serotype closely related to ; nonetheless, the parumapertus agent was not further characterized or studied. To our knowledge, no isolates of the parumapertus agent remain in any rickettsial culture collection, which precludes contemporary phylogenetic placement of this enigmatic SFGR.

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Article Synopsis
  • A study in Bangladesh aimed to identify infections from Rickettsia, Coxiella, Leptospira, Bartonella, and Chikungunya virus in patients with fever who visited hospitals between December 2008 and November 2009.
  • Out of 720 patients tested, 37% were found to be infected with Rickettsia, with specific cases linked to different types such as spotted fever and scrub typhus.
  • The findings suggest that rickettsial infections are common but often overlooked, highlighting the need for updated clinical guidelines to improve diagnosis and treatment.
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