Publications by authors named "Kjemtrup A"

In response to notable increases in tick-associated illnesses in the United States, recent public health policies encouraged multi-sector collaborative approaches to preventing vector-borne diseases. Primary prevention strategies focus on educating the public about risks for tick-borne diseases and encouraging adoption of personal protection strategies. Accurate descriptions of when and where people are at risk for tick-borne diseases aid in the optimization of prevention messaging.

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Between January 1, 2011, and December 31, 2017, over 12,000 case reports of Lyme disease (LD) were submitted to the California Reportable Disease Information Exchange for further investigation. The number of case reports has tripled compared to previous years, emphasizing the need for efficient estimation and classification methods. We evaluated whether estimation procedures can be implemented in a low-incidence state such as California to correctly classify a case of LD, similar to those procedures used in high-incidence states.

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Article Synopsis
  • * Between July 2023 and January 2024, California reported six RMSF cases linked to exposure in Tecate, Mexico, raising concerns as it was previously not identified as a high-risk area, and three of these cases were fatal.
  • * Effective detection of RMSF cases necessitated collaborative efforts among various public health agencies, highlighting the need for increased awareness among healthcare providers to enable quicker diagnoses and treatments on both sides of the U.S.-Mexico border.
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The etiologic agent of Pacific Coast tick fever (PCTF), a moderately severe tickborne illness that resembles Rocky Mountain spotted fever (RMSF), was first isolated in 1966 from specimens of Dermacentor occidentalis (the Pacific Coast tick) obtained in California. For several decades, this bacterium was identified ambiguously as the unclassified spotted fever group Rickettsia species 364-D, Rickettsia 364, or Rickettsia philipii. However, none of these epithets satisfied criteria of formal bacterial nomenclature.

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Flea-borne spotted fever and flea-borne (murine) typhus are rickettsioses caused by Rickettsia felis and Rickettsia typhi, respectively, and typically present as undifferentiated febrile illnesses. The relative contribution of these agents to flea-borne rickettsioses in California is unclear. We have developed a duplex reverse transcription real-time polymerase chain reaction (RT-rtPCR) assay targeting R.

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  • * A new rickettsial pathogen, Rickettsia sp. CA6269, was identified in two patients in northern California, causing severe illness similar to Rocky Mountain spotted fever.
  • * The study highlights potential misidentification of Rickettsia sp. CA6269 as R. rickettsii due to cross-reactivity in diagnostic tests and introduces a specific real-time PCR for accurate detection and understanding of this emerging pathogen.
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Article Synopsis
  • - Rocky Mountain spotted fever (RMSF) is a serious, tick-borne disease caused by Rickettsia rickettsii, affecting primarily impoverished communities in the southwestern U.S. and northern Mexico, with high fatality rates linked to poor diagnosis and treatment delays.
  • - The disease is exacerbated by free-roaming dogs and widespread brown dog tick populations, with the U.S. facing a 5%-7% fatality rate while Mexico often exceeds 30%.
  • - One Health professionals are working on prevention and management strategies, including public education, urgent treatment protocols, vaccine research, and new methods to control tick populations and improve management of dog populations.
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The Pacific Coast tick (Dermacentor occidentalis Marx, 1892) is a frequently encountered and commonly reported human-biting tick species that has been recorded from most of California and parts of southwestern Oregon, southcentral Washington, and northwestern Mexico. Although previous investigators have surveyed populations of D. occidentalis for the presence of Rickettsia species across several regions of California, populations of this tick have not been surveyed heretofore for rickettsiae from Baja California, Oregon, or Washington.

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Flea-borne typhus (FBT), also referred to as murine typhus, is an acute febrile disease in humans caused by the bacteria Rickettsia typhi. Currently, cases of FBT are reported for public health surveillance purposes (i.e.

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Article Synopsis
  • Tick-borne parasites like spp. can affect various vertebrate hosts, and climate change may alter their transmission patterns, raising concerns about transfusion-transmitted infections (TTB) in humans, particularly in North America.
  • TTB can lead to moderate-to-severe illness in patients, and while most cases are reported in the U.S., increased awareness and changing epidemiology could affect case numbers globally due to climate factors.
  • Microbiologists are crucial in minimizing TTB risks by developing blood donor screening methods, investigating cases, and creating guidelines, particularly in both endemic and non-endemic regions as the landscape of transmission evolves.
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Soft tick relapsing fever (STRF) (also known as tickborne relapsing fever) is a rare infection caused by certain Borrelia spirochetes and transmitted to humans by soft-bodied Ornithodoros ticks. In the United States, acquisition of STRF is commonly associated with exposure to rustic cabins, camping, and caves. Antibiotic treatment is highly effective for STRF, but without timely treatment, STRF can result in severe complications, including death.

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Article Synopsis
  • Borrelia miyamotoi infections have been indicated in California through blood tests.
  • A case was identified in an immunocompromised man, where diagnosis was supported by analyzing DNA from his blood.
  • The findings suggest that the infection was contracted within California.
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  • The text indicates that there has been a correction made to the original article linked by DOI: 10.1371/journal.pntd.0010738.
  • This correction is likely to address an error or clarify information presented in the original publication.
  • Readers interested in the findings or conclusions of the article should refer to the corrected version for accurate information.
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Lyme disease (LD), caused by the bacterium Borrelia burgdorferi, is transmitted to humans in California through the bite of infected blacklegged ticks (Ixodes pacificus). Overall, the incidence of LD in California is low: approximately 0.2 confirmed cases per 100,000 population.

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  • * An analysis of 78 RMSF cases from 1980 to 2019 indicated a rise in incidence over the last two decades, particularly among Hispanic/Latino populations, despite a drop in confirmed case percentages.
  • * Many cases are linked to Southern California and Mexico, attributed to the spread of certain ticks; most patients faced serious illness, highlighting the challenge of diagnosing RMSF due to its nonspecific symptoms.
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In the past few decades, reported human cases of Colorado tick fever in the western United States have decreased dramatically. The goal of this study was to conduct surveillance for Colorado tick fever virus (CTFV) in ticks in recreational sites in Colorado, Wyoming, and California to determine whether the virus is still present in ticks from these states. Surveillance focused on regions where surveys had been conducted in the 1950s, 1960s, and 1970s.

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Babesia spp. are tickborne parasites that cause the clinical infection babesiosis, which has an increasing incidence in the United States. We performed an analysis of hospitalizations in the United States during 2010-2016 in which babesiosis was listed as a diagnosis.

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The western blacklegged tick, Ixodes pacificus, an important vector in the western United States of two zoonotic spirochetes: Borrelia burgdorferi (also called Borreliella burgdorferi), causing Lyme disease, and Borrelia miyamotoi, causing a relapsing fever-type illness. Human cases of Lyme disease are well-documented in California, with increased risk in the north coastal areas and western slopes of the Sierra Nevada range. Despite the established presence of B.

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Background: Dogs are vulnerable to pathogens transmitted by brown dog ticks. An epidemic of Rocky Mountain spotted fever (RMSF) is underway in Mexicali, a Mexican city bordering California affecting people and dogs; several human cases have been reported in California residents who travelled to Mexico. To evaluate risks of RMSF, we conducted seroprevalence surveys in Imperial County in 2016 and 2017 using dogs as sentinels.

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We describe a case of hantavirus pulmonary syndrome in a patient exposed to Sin Nombre virus in a coastal county in California, USA, that had no previous record of human cases. Environmental evaluation coupled with genotypic analysis of virus isolates from the case-patient and locally trapped rodents identified the likely exposure location.

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Babesiosis is a potentially fatal tick-borne zoonotic disease caused by a species complex of blood parasites that can infect a variety of vertebrates, particularly dogs, cattle, and humans. In the United States, human babesiosis is caused by two distinct parasites, Babesia microti and Babesia duncani. The enzootic cycle of B.

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Human babesiosis is a tick-borne protozoal disease of increasing clinical significance in North America. Most cases in the eastern and Midwestern regions of the United States are reportedly due to Babesia microti infections. By contrast, most human infections reported in California and Washington have been attributed to a new species that was first identified in 1991 and subsequently named Babesia duncani.

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Rocky Mountain spotted fever (RMSF) is an emerging public health concern near the US-Mexico border, where it has resulted in thousands of cases and hundreds of deaths in the past decade. We identified 4 patients who had acquired RMSF in northern Mexico and subsequently died at US healthcare facilities. Two patients sought care in Mexico before being admitted to US-based hospitals.

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Lyme disease is the most common tick-borne disease in temperate regions of North America, Europe and Asia, and the number of reported cases has increased in many regions as landscapes have been altered. Although there has been extensive work on the ecology and epidemiology of this disease in both Europe and North America, substantial uncertainty exists about fundamental aspects that determine spatial and temporal variation in both disease risk and human incidence, which hamper effective and efficient prevention and control. Here we describe areas of consensus that can be built on, identify areas of uncertainty and outline research needed to fill these gaps to facilitate predictive models of disease risk and the development of novel disease control strategies.

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