Important Clinical Features of Japanese Spotted Fever

Survey of Rickettsia species in hematophagous arthropods from endemic areas for Japanese spotted fever in China

Japanese spotted fever (JSF) is caused by Rickettsia japonica, mainly vectored by hard ticks. However, whether R. japonica can be transmitted by other arthropods remains unknown. Moreover, it is of interest to investigate whether other Rickettsia species cause spotted fever in endemic areas. In this study, a survey of Rickettsia species was performed in hematophagous arthropods (mosquitoes, tabanids, and ticks) from endemic areas for JSF in Hubei Province, central China. The results showed that the diversity and prevalence of Rickettsia species in mosquitoes are low, suggesting that mosquitoes may not be the vector of zoonotic Rickettsia species. A novel Rickettsia species showed a high prevalence (16.31%, 23/141) in tabanids and was named "Candidatus Rickettsia tabanidii." It is closely related to Rickettsia from fleas and mosquitoes; however, its pathogenicity in humans needs further investigation. Five Rickettsia species were identified in ticks. Rickettsia japonica, the agent of JSF, was detected only in Haemaphysalis longicornis and Haemaphysalis hystricis, suggesting that they may be the major vectors of R. japonica. Notably, two novel species were identified in H. hystricis ticks, one belonging to the spotted fever group and the other potentially belonging to the ancestral group. The latter one named "Candidatus Rickettsia hubeiensis" may provide valuable insight into the evolutionary history of Rickettsia.

Atypical Rickettsia japonica Infection Involving Critical Illness Diagnosed by Metagenomic Next-Generation Sequencing: A Case Report

Background

Rickettsia japonica infection is a rare disease, it is rare to report critical and severe case caused by this disease in Zhejiang Province, China.

Patient Concerns

We report a patient who initially sought medical attention due to fever and developed coma and convulsions during treatment. The patient did not develop typical eschar and rash. Eventually, the patient needed to be treated in the intensive care unit due to acute respiratory failure.

Diagnoses

The patient was diagnosed with Rickettsia japonica bloodstream infection by metagenomic next-generation sequencing (mNGS).

Outcomes

Due to the critical illness, the patient was transferred to the intensive care unit, received doxycycline and other treatments, and rapidly recovered and discharged.

Conclusion

The patient developed a critical illness after being infected with Rickettsia, when the medical history is unclear and clinical symptoms and signs are atypical, it is necessary to use mNGS examination for diagnosis.

Diagnosing and reintegrating traceability of infectious diseases via metagenomic next-generation sequencing: Study of a severe case of Rickettsia japonica infection

Background

In this study, we present a case of Japanese spotted fever (JSF) caused by Rickettsia japonica and use this case to investigate the process of diagnosing and reintegrating traceability of infectious diseases via metagenomic next-generation sequencing (mNGS).

Methods

From data relating to epidemiological history, clinical and laboratory examinations, and mNGS sequencing, a diagnosis of severe JSF was concluded.

Results

A detailed field epidemiological investigation discovered parasitic Haemaphysalis longicornis from a host animal (dog) in the domicile of the patient, within which R. japonica was detected, along with a diverse array of other potentially pathogenic microorganisms that could cause other infectious diseases.

Conclusion

The mNGS provided an efficient method to diagnose JSF infection. This methodology could also be applied to field epidemiological investigations to establish the traceability of infectious diseases.

Prompt diagnosis and appropriate treatment of Japanese spotted fever: A report of three cases

Background

Japanese Spotted Fever (JSF) is a Spotted Fever Group (SFG) rickettsiosis caused by Rickettsia japonica. More than 300 cases are diagnosed annually in Japan, and the number of reported cases has been increasing. Correct diagnoses depend on the triad of symptoms and signs, including fever, rash, and eschar, which can be seen at the site of vector bites. JSF is not life-threatening if treated appropriately without diagnostic delay but there are some fatal cases every year. This negligence leads to disseminated intravascular coagulation (DIC) and multiple organ failure (MOF), and poor prognoses, consequently. Prompt diagnosis of JSF is difficult when the aforementioned triad of signs and symptoms is not initially present.

Case report

This report describes three JSF cases: an 87-year-old woman with fever, shock, pancytopenia, DIC, and MOF; a 79-year-old man with fever and difficulty in movement; and a 78-year-old man with fever, general fatigue, and appetite loss. All patients had a rash and eschar, which led to prompt diagnosis and appropriate treatment immediately. All patients were treated without any complications.

Why should an emergency physician be aware of this?

As mentioned above, JFS can be fatal with delayed diagnoses and treatment initiations. The key for a prompt diagnosis is to recognize the triad of symptoms and signs, which are not often present initially, and it makes JSF diagnosis challenging. Repeated comprehensive physical examinations are essential for prompt diagnosis and improve prognosis of JSF.

Complete genome sequencing and comparative genomic analyses of a new spotted-fever Rickettsia heilongjiangensis strain B8

Rickettsia heilongjiangensis, a tick-borne obligate intracellular bacterium and causative agent of spotted fever in China, has attracted increasing concern regarding its capability in causing human rickettsiosis. Here, we conducted a genomic analysis of a new R. heilongjiangensis strain B8 (B8) isolated from the serum of a patient who had been bitten by a Haemaphysalis longicornis tick in Anhui Province, China. The present study sought to identify exclusive genes that might be associated with the pathogenicity of B8 using comparative genomics. Specifically, the sequences of B8 were assembled into one circular chromosome of 1,275,081 bp and predicted to contain 1447 genes. Comparative genome analyses were performed based on the genome of B8 and 28 spotted fever group (SFG) rickettsial genomes deposited in NCBI. Phylogenomic analyses indicated the B8 strain was clustered within the R. heilongjiangensis species; however, a sum of 112 and 119 B8-unique genes was identified when compared with R. heilongjiangensis and R. japonica strains, respectively. Functional annotation analyses revealed that these B8-unique genes were mainly annotated to defence mechanisms, lipid transport and metabolism, cell wall/membrane/envelope biogenesis. These data indicate B8 rather represents a previously undescribed human-pathogenic SFG rickettsia lineage, which may be an intermediate lineage of R. heilongjiangensis and R. japonica. Overall, this study isolated a new strain of R. heilongjiangensis in East-Central China for the first time, and provided potential B8-unique genetic loci that could be used for the discrimination of B8 from other R. heilongjiangensis and closely related SFG Rickettsial strains.

Complicated Japanese Spotted Fever With Meningitis in an Older Patient: A Case Report

Japanese spotted fever (JSF) poses a significant public health challenge, mainly due to its atypical presentation in specific demographics. This report details a unique case of JSF in an 89-year-old female who was admitted to a rural hospital exhibiting generalized pain and rapid cognitive decline but no rash. Initially misdiagnosed as polymyalgia rheumatica, her condition was complicated by thrombocytopenia and altered mental state, prompting consideration of tick-borne illnesses. Subsequent serological analysis confirmed JSF despite the absence of its hallmark rash. The patient's condition escalated to include bacteremia and aseptic meningitis. Treatment involved a regimen of minocycline and meropenem, along with endoscopic cauterization of a bleeding rectal ulcer. After treatment, the patient showed improvement and was transferred for rehabilitation. This case highlights the criticality of considering JSF in elderly patients within endemic areas, even when classic symptoms like erythema and petechiae are absent. It underscores the necessity for broad diagnostic perspectives, especially in atypical presentations, and the integration of comprehensive care approaches. The involvement of caregivers and relatives in early detection and seeking medical care promptly is crucial. The report illustrates the complexities in diagnosing and managing advanced JSF cases and stresses the importance of early serological testing and adaptive treatment strategies in managing such challenging cases.

A Case of Critical Japanese Spotted Fever in Zhejiang, China

Background

Japanese spotted fever (JSF) is a rare disease, caused by Rickettsia japonica; no case has been reported in Zhejiang Province, China.

Case Presentation

An elderly woman presented to the hospital with abdominal pain and fever. Her condition rapidly worsened with severe complications, such as multiple organ failure and central nervous system damage. The presence of R. japonica was quickly detected by metagenomic next-generation sequencing. On the basis of combined clinical manifestations and laboratory results, critical JSF was diagnosed and treated with doxycycline. The patient showed good prognosis. Typical symptoms (eschar and rash) were not observed in the early stage, consequently increasing the difficulty of clinical diagnosis.

Conclusion

The delay of treatment caused by non-specific symptoms is an important factor affecting the progression of JSF. As an emerging pathogen detection method, mNGS has been successfully applied for disease diagnosis and treatment, and can be an important complement for the diagnosis of this disease.

Trends in the Incidence of Japanese Spotted Fever in Japan: A Nationwide, Two-Decade Observational Study from 2001-2020

The worldwide spread of tick-borne diseases (TBDs) has become a public health concern. Therefore, this study aimed to clarify trends in the incidence of Japanese spotted fever (JSF), one of Japan's most prevalent TBDs. Weekly infectious disease reports were used to calculate the annual incidence rates (AIRs) of JSF. Data were stratified by age and sex, and joinpoint regression analysis was performed to estimate the annual percentage change (APC). AIR and APC were geographically compared among the 47 prefectures. A total of 3,453 JSF cases were observed from 2001 to 2020. The AIR per 100,000 population was 0.03 in 2001, which increased approximately 10-fold to 0.33 in 2020. The average APC (AAPC) during the study period was 12.3% (95% CI: 10.7-13.9). By age group, the incidence of JSF increased more rapidly among the older population: 11.5% (95% CI: 10.1-12.9) in those aged ≥ 65 years and 8.9% (95% CI: 6.4-11.5) in those aged < 50 years. Although the AIR over the past two decades was higher in climatically warm regions located in southwestern Japan and on the Pacific coast, increases in the AAPC were notable in colder regions located in eastern Japan. The incidence of JSF continues to increase in Japan, especially among older populations and in eastern prefectures, where the disease has not been previously diagnosed.

Japanese Spotted Fever Associated with Mild Encephalitis/Encephalopathy with a Reversible Splenial Lesion

A 58-year-old woman had disseminated intravascular coagulation (DIC) and septic shock caused by Japanese spotted fever (JSF). Following treatment with minocycline, her general condition gradually improved; however, her disorientation persisted. Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) type II was diagnosed based on brain magnetic resonance imaging (MRI) showing a hyperintense area in the splenium of the corpus callosum and bilateral cerebral white matter on diffusion-weighted imaging. Thereafter, her consciousness gradually improved, but she continued to experience difficulty concentrating and attention deficits. MERS type II may take longer to improve than type I, and long-term follow-up is required.

Increasing Risk of Tick-Borne Disease through Growth Stages in Ticks

Rickettsia and Coxiella spp. are pathogens transmitted by ticks to humans. However, the developmental stage of the tick carrying the greatest risk of infection is unknown. Detection of pathogen-specific genes proves that ticks carrying Rickettsia or Coxiella spp. constitute a reservoir of infection. However, conventional PCR methods are unable to quantitate the pathogens within ticks. In the present study, we collected ticks in the endemic area of Japanese spotted fever, caused by Rickettsia japonica, and determined the rate of tick-borne pathogens carried by the ticks. As a method of evaluation, next-generation sequencing was used to estimate the proportion of pathogens in 10 adult and 10 larval ticks. Ticks were identified Haemaphysalis longicornis (H.L) from the results of the sequencing of PCR products amplified using tick identification-specific primers. The gene detection rates were 10/10 for Rickettsia sp. and 10/10 for Coxiella sp. among the adult ticks. For the larval ticks, the ratios were 7/10 and 5/10 for Rickettsia sp. and Coxiella sp., respectively. The largest proportion of Coxiella sp.-specific DNA reached 96% in one adult tick. The proportion of Rickettsia sp. genes ranged from 1.76% to 41.81% (mean, 15.56%) in the adult ticks. The proportions of Coxiella and Rickettsia spp. genes in the larvae ranged from 0% to 27.4% (mean 5.86%) and from 0% to 14.6% (mean 3.38%), respectively. When the percentage of Rickettsia sp., out of all pathogens detected via next-generation sequencing, was analyzed between the adult and larval stages of the ticks, a significant difference was observed at p = 0.0254. For Coxiella sp., a highly significant difference (p < 0.0001) was found between the adult and larval stages of the ticks. In conclusion, the detection rates and proportions of Rickettsia and Coxiella spp. genes were highest in adult H.L ticks. The risk of contracting tick-borne infections may increase with bites from adult ticks, especially those harboring Coxiella sp.

Epidemiological study of ticks harbouring Aeromonas hydrophila in areas endemic and non-endemic to Japanese-spotted fever

OBJECTIVES

Aeromonas spp. often cause life-threatening diseases, including necrotizing fasciitis, which may lead to septic shock and ultimately death. Aeromonas infections are believed to be transmitted via minor wounds or the consumption of fresh fish. However, after the detection of Aeromonas hydrophila in ticks in areas endemic to Japanese-spotted fever (JSF), a novel transmission route of A. hydrophila (i.e., via tick bites) has been proposed. We investigated the prevalence of A. hydrophila in ticks in areas endemic and not endemic to JSF in the Mie Prefecture, Japan.

METHODS

We collected ticks from endemic and nonendemic areas in summer and winter and assessed them for presence of A. hydrophila using polymerase chain reaction.

RESULTS

Six A. hydrophila isolates were obtained from 95 ticks in endemic areas, whereas one A. hydrophila isolate was obtained from 142 ticks in non-endemic areas, in summer. All ticks that harboured A. hydrophila were Haemaphysalis longicornis (H.L); these ticks were almost at the larval stage and also carried Rickettsia spp. in the endemic area. In contrast, 51 and 41 ticks in the endemic and non-endemic areas were captured in winter, respectively; A. hydrophila was not detected in these.

CONCLUSIONS

This study revealed the prevalence of tick-borne A. hydrophila. Therefore, the risk of transmission of A. hydrophila via a tick bite should be considered in the following conditions: areas abundant in H. L. harbouring Rickettsia spp., in areas endemic for JSF, presence of ticks in the larval stage and during the summer season.

Tick Control in a Connected World: Challenges, Solutions, and Public Policy from a United States Border Perspective

Ticks are able to transmit the highest number of pathogen species of any blood-feeding arthropod and represent a growing threat to public health and agricultural systems worldwide. While there are numerous and varied causes and effects of changes to tick-borne disease (re)emergence, three primary challenges to tick control were identified in this review from a U.S. borders perspective. (1) Climate change is implicated in current and future alterations to geographic ranges and population densities of tick species, pathogens they can transmit, and their host and reservoir species, as highlighted by Ixodes scapularis and its expansion across southern Canada. (2) Modern technological advances have created an increasingly interconnected world, contributing to an increase in invasive tick species introductions through the increased speed and frequency of trade and travel. The introduction of the invasive Haemaphysalis longicornis in the eastern U.S. exemplifies the challenges with control in a highly interconnected world. (3) Lastly, while not a new challenge, differences in disease surveillance, control, and management strategies in bordering countries remains a critical challenge in managing ticks and tick-borne diseases. International inter-agency collaborations along the U.S.-Mexico border have been critical in control and mitigation of cattle fever ticks (Rhipicephalus spp.) and highlight the need for continued collaboration and research into integrated tick management strategies. These case studies were used to identify challenges and opportunities for tick control and mitigation efforts through a One Health framework.

Japanese Spotted Fever and Irreversible Renal Dysfunction during Immunosuppressive Therapy after a Living-Donor Kidney Transplant

Ten years ago, a 56-year-old woman with a history of IgA nephropathy who received a living-donor kidney transplant across ABO barriers was managed with immunosuppressive drugs. The kidney transplant donor was her father who had poor kidney function. The patient’s renal function was stable for 10 years. The patient visited our department with a complaint of skin rash, occurring 2 days after an onset of fever. Although a skin rash is atypical for Japanese spotted fever (JSF), we suspected JSF and started treatment with minocycline because we found a scar suggestive of an eschar. Furthermore, the blood test results were similar to those associated with JSF, and the patient lived in a JSF-endemic area. The patient’s symptoms improved after 1 week. She was diagnosed with JSF by serological tests against Rickettsia japonica. JSF usually does not cause any complications after recovery. However, the patient’s renal function did not completely recover. JSF can cause an atypical rash in patients taking excessive immunosuppressive drugs. Early treatment is required for patients with suspected JSF to prevent complications of renal dysfunction after receiving a living-donor kidney transplant.

A contrivance of tick removal to prevent skin damage: Injection into the tick before removal

Ticks adhere to the host skin outdoors. Methods for tick removal without causing skin damage are controversial, and surgical excision along with the skin is mainly performed. A 6-week-old infant who lived indoors with a family cat contracted a tick bite. Tick killing before removal by injection of carbocaine into the tick led to successful removal without damaging the skin. This method can be useful for preventing damage to the skin during tick removal. A pet that roams outdoors can be a transmitter of ticks. We should be aware that this risk of tick bites can be hidden indoors.

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The tick removal method without damage of the skin has been controversial.

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Tick killing with the injection into the tick can prevent damage of the skin.

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A pet roaming outdoors can be a transmitter of ticks to an infant living indoors.

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A risk of tick bites can be hidden even indoors.

Japanese Spotted Fever Complicated With Life-Threatening Ventricular Tachycardia and Acute Cardiac Damage

A 67-year-old man with high-grade fever and systemic erythema visited our hospital. Based on his symptoms and history of outdoor activities, we considered the possibility of rickettsial diseases, especially Japanese spotted fever (JSF). He was treated with antibiotics. After hospitalization, the patient complained of palpitations, and electrocardiography revealed ventricular tachycardia (VT). He was successfully treated with electrical defibrillation. Moreover, echocardiography showed decreased wall motion at the apex. However, coronary angiography showed no coronary artery-related stenosis. JSF was confirmed via polymerase chain reaction using a biopsy sample of the erythema. Subsequently, the patient was discharged without complications. To our knowledge, this is the first reported case of JSF complicated with VT and acute cardiac damage.

Complete mitochondrial genome of Asian longhorned tick, Haemaphysalis longicornis, Neumann, 1901 (Acari: Ixodida: Ixodidae) identified in the United States

Haemaphysalis longicornis (Ixodida: Ixodidae), the Asian longhorned tick, which is native to temperate East Asia, has been recently detected in the northeastern region of the United States, drawing concerns about its potential impact on the US animal and public health sectors. Knowledge about the genetic features of H. longicornis found in the US is limited. Therefore, we sequenced the complete mitochondrial genome (mt-genome) from two H. longicornis ticks recently collected in the State of New York, USA, in 2020. These ticks were morphologically identified and tested for tick-borne pathogens at the Connecticut Veterinary Medical Diagnostic Laboratory (Storrs, CT). The mt-genome was 14,694 bp in length and encoded 37 genes, including 13 protein-coding genes, 22 transfer RNAs, and two ribosomal RNAs. Phylogenetic analysis showed that the mt-genome clustered with those of other H. longicornis identified in China. The mt-genome sequence was 99.7% identical to a H. longicornis mt-genome (GenBank: MK439888) collected in China. The cox1 gene haplotype in these ticks belonged to the H1 type, which is the dominant haplotype present in central NJ and Staten Island, NY. The complete mt-genome data are needed to provide insights into genetic changes and phylogenetic studies of H. longicornis ticks.

Transition of Serum Cytokine Concentration in Rickettsia japonica Infection

(1) Background. Rickettsia japonica (R. japonica) infection induces severe inflammation, and the disappearance of eosinophil in the acute stage is one of the phenomena. (2) Materials and Methods. In the current study, we measured the serum concentrations of Th1, Th2, and Th17 cytokines in the acute and recovery stages. (3) Results. In the acute phase, IL-6 and IFN-γ levels were elevated and we speculated that they played a role as a defense mechanism against R. japonica. The high concentration of IFN-γ suppressed the differentiation of eosinophil and induced apoptosis of eosinophil, leading to the disappearance of eosinophil. On day 7, IL-6 and IFN-γ concentrations were decreased, and Th2 cytokines such as IL-5 and IL-9 were slightly increased. On day 14, eosinophil count recovered to the normal level. The transition of serum cytokine concentration in R. japonica infection was presented. (4) Conclusions. IL-6 and IFN-γ seem to be critical cytokines as defense mechanism against R. japonica in the acute phase, and this may deeply connect to the decrease of eosinophil.

First glimpse into the origin and spread of the Asian longhorned tick, Haemaphysalis longicornis, in the United States

Established populations of Asian longhorned ticks (ALT), Haemaphysalis longicornis, were first identified in the United States (US) in 2017 by sequencing the mitochondrial cytochrome c oxidase subunit I (cox1) 'barcoding' locus followed by morphological confirmation. Subsequent investigations detected ALT infestations in 12, mostly eastern, US states. To gain information on the origin and spread of US ALT, we (1) sequenced cox1 from ALT populations across 9 US states and (2) obtained cox1 sequences from potential source populations [China, Japan and Republic of Korea (ROK) as well as Australia, New Zealand and the Kingdom of Tonga (KOT)] both by sequencing and by downloading publicly available sequences in NCBI GenBank. Additionally, we conducted epidemiological investigations of properties near its initial detection locale in Hunterdon County, NJ, as well as a broader risk analysis for importation of ectoparasites into the area. In eastern Asian populations (China/Japan/ROK), we detected 35 cox1 haplotypes that neatly clustered into two clades with known bisexual versus parthenogenetic phenotypes. In Australia/New Zealand/KOT, we detected 10 cox1 haplotypes all falling within the parthenogenetic cluster. In the United States, we detected three differentially distributed cox1 haplotypes from the parthenogenetic cluster, supporting phenotypic evidence that US ALT are parthenogenetic. While none of the source populations examined had all three US cox1 haplotypes, a phylogeographic network analysis supports a northeast Asian source for the US populations. Within the United States, epidemiological investigations indicate ALT can be moved long distances by human transport of animals, such as horses and dogs, with smaller scale movements on wildlife. These results have relevant implications for efforts aimed at minimizing the spread of ALT in the United States and preventing additional exotic tick introductions.