Rocky Mountain Spotted Fever in Children along the US‒Mexico Border, 2017-2023.

Rocky mountain spotted fever (RMSF) causes significant illness and death in children. Although historically rare in California, USA, RMSF is endemic in areas of northern Mexico that border California. We describe 7 children with RMSF who were hospitalized at a tertiary pediatric referral center in California during 2017-2023. Five children had recent travel to Mexico with presumptive exposure, but 2 children did not report any travel outside of California. In all 7 patients, Rickettsia rickettsii DNA was detected by plasma microbial cell-free next-generation sequencing, which may be a useful diagnostic modality for RMSF, especially early in the course of illness, when standard diagnostic tests for RMSF are of limited sensitivity. A high index of suspicion and awareness of local epidemiologic trends remain most critical to recognizing the clinical syndrome of RMSF and initiating appropriate antimicrobial therapy in a timely fashion.

The potential use of arginine kinase from the brown tick Rhipicephalus sanguineus as a biomarker for vector exposure in the surveillance of Rocky Mountain spotted fever.

The brown dog tick (Rhipicephalus sanguineus) is the vector of Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever (RMSF) in Northern Mexico and Southwestern United States. The immune response to a tick protein in the sera of humans or animals may reveal the zones with a high propensity to acquire RMSF, and vector control strategies may be focused on these zones. Arginine kinase (AK) is a highly antigenic invertebrate protein that may serve as a marker for tick exposure. We used R. sanguineus recombinant AK in an indirect ELISA assay with RMSF-positive patient sera. The response to AK was significantly higher against the sera of RMSF patients than the control sera from healthy participants without contact with dogs. To validate the antigenicity of tick AK, we mutated one predicted conformational epitope to alanine residues, which reduced the recognition by RMSF patients' immunoglobulins. This preliminary result opens a perspective towards the development of a complimentary technique based on RsAK as an antigen biomarker for vector serological surveillance for Rickettsia RMSF prevention.

Sterilization of free-ranging female capybaras (Hydrochoerus hydrochaeris): a comparison between two surgical techniques.

This study evaluated two surgical sterilization techniques in free-ranging female capybaras (n = 21). The first group underwent uterine horn ligature (HL; n = 11), while the second was subjected to partial salpingectomy (S; n = 10). We assessed total operative time, incision length, the ease of identifying reproductive structures, the adequacy of exposure for surgical performance through flank or midline approaches, and the extent of abdominal viscera manipulation for each method. The HL method emerged as faster, with an average operative time difference of 16 minutes. In the S group, a flank mini-laparotomy over the ovarian topography facilitated easy exposure of the ipsilateral ovary and uterine tube, enabling ligature and partial resection of the uterine tube but not the uterine horn exposure. However, accessing the contralateral uterine tube without a bilateral incision was impractical, thus prolonging the total operative time due to the need for patient repositioning and new antisepsis procedures. Conversely, a post-umbilical approach for the HL method necessitated only one mini-laparotomy incision, offering ample uterine exposure for hysterotomy in pregnant females. Both methods involved minimal abdominal viscera manipulation and resulted in no fatalities or postoperative complications. Although direct comparison is limited by the distinct sterilization techniques and surgical approaches, this study underscores the challenges and surgical access of each method. Our findings endorse the HL technique as an effective contraception method for female capybaras to prevent the birth of seronegative offspring that could amplify Rickettsia sp., the causative agent of Brazilian spotted fever.

A case report of fatal Rickettsia japonica bloodstream infection in Zhejiang, China.

Japanese spotted fever (JSF) is an emerging acute febrile natural infectious disease caused by the neglected zoonotic pathogen Rickettsia japonica. Here we reported a 64-year-old female patient who initially presented to the local hospital with an intermittent fever of unknown origin (FUO). A systemic, evident edema and eschar on the skin of the patient's upper limb was observed. The patient was diagnosed with critical Rickettsia japonica bloodstream infection by Q-mNGS and treated with doxycycline, as well as symptomatic treatments. Unfortunately, the patient passed away as a result of complications of septic shock and multiple organ and acute respiratory failure. Delayed treatment resulting from the nonspecific clinical symptoms in the early stages of infection can lead to fatal complications. Q-mNGS is an emerging pathogen detection method with the advantages of comprehensive detection, high accuracy and sensitivity and should be promoted and applied by clinicians.

Japanese spotted fever is an emerging infectious disease caused by the bacteria Rickettsia japonica. The onset of symptoms in patients is very sudden once infected. Here, we reported a 64-year-old female patient who experienced recurrent fever with an unknown cause. The patient was diagnosed with Rickettsia japonica infection after testing and received antibiotic treatment. However, delays in treatment led to continuous worsening of the condition and ultimately death. We emphasize the value of early, broader testing in the diagnosis of rare infections to detect infection early.

Conceptual Framework for Community-Based Prevention of Brown Dog Tick-Associated Rocky Mountain Spotted Fever.

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. By using a One Health approach, interdisciplinary teams can identify communities at risk and prevent severe or fatal RMSF in humans before cases occur. We have developed a conceptual framework for RMSF prevention to enable communities to identify their RMSF risk level and implement prevention and control strategies.

Identifying New Areas of Endemicity and Risk Factors for Rickettsia conorii subsp. conorii Infection: Serosurvey in Rural Areas of Romania.

BACKGROUND: Mediterranean spotted fever (MSF) is an emerging tick-borne disease caused by Rickettsia conorii subsp. conorii, primarily prevalent in Mediterranean and Southern Europe. We aimed to evaluate MSF seroprevalence and risk factors in non-endemic rural areas of Romania. METHODS: We conducted a serosurvey in five counties not under MSF surveillance by testing 459 serum samples from adult volunteers for specific IgG antibodies using ELISA. Participants answered a questionnaire regarding demographics and MSF risk factors. RESULTS: The median age of the participants was 60 years and 329 (71.7%) were female. Overall, 64 (13.9%) samples tested positive for IgG anti-R. conorii, with rates ranging from 7.1% in Sibiu to 22.4% in Hunedoara. The median age of the positive individuals was 68 years, with a significantly higher seropositivity rate of 54.7% among those over 65 years (p = 0.01). Among those positive, 53 (82.8%) owned different household animals; 24 (37.5%) had daily contact with dogs, and 27 (42.2%) with livestock; 17 (26.6%) noted tick infestations of animals, and 23 (35.9%) reported tick bites. CONCLUSIONS: This study revealed an important seroprevalence of MSF in Romanian areas considered non-endemic, indicating an expansion of its geographical range, probably due to climate change, and emphasizing the importance of enhanced surveillance and diagnostic capabilities nationwide.

Isolation of Rickettsia heilongjiangensis (Strain AH-19) from Haemaphysalis longicornis on a Wild Hedgehog in Anhui Province, China.

Background: Spotted fever group rickettsioses, caused by rickettsiae of the spotted fever group, pose a significant zoonotic threat to public health. In endemic areas of Anhui Province, China, the ecology and transmission dynamics of these pathogens remain under investigation. Methods: We isolated a rickettsial strain from Haemaphysalis longicornis ticks collected from a wild hedgehog in the Dabie Mountain area. Molecular identification and phylogenetic analysis were employed to confirm the strain. Pathological examinations of the hedgehog's tissues were conducted to assess the potential impact of the infection. Results: The isolated strain was identified as R. heilongjiangensis strain AH-19. Pathological examination revealed significant tissue alterations, including cellular vacuolization, necrosis, and disarray of tissue architecture. It remains uncertain whether these changes were directly attributable to the rickettsial infection or other factors. Conclusions: The identification of R. heilongjiangensis strain AH-19 in H. longicornis suggests that hedgehogs may serve as reservoir hosts in the Dabie Mountain area.Further research is needed to clarify their role in the ecology and epidemiology of this pathogen, which could inform future public health strategies.

Ticks and tick-borne pathogens in selected abattoirs and a slaughter slab in Kumasi, Ghana.

BACKGROUND: Ticks are vectors of pathogens that affect the health of animals and humans. With the constant trade of livestock across borders, there is the risk of new tick species invasion accompanied by the spread of infectious tick-borne pathogens. AIM: This study sought to determine the diversity of tick species within abattoirs and a slaughter slab as well as identify the pathogens carried by these ticks. METHODS: The ticks were collected from slaughtered cattle, identified and screened for pathogens using PCR and sequencing. RESULTS: A total of 371 ticks were collected from slaughtered cattle across the three sampling sites: Kumasi abattoir (288, 77.63%), Akwatia Line slaughter slab (52, 14.02%) and Suame abattoir (31, 8.35%). The predominant species was Amblyomma variegatum (85.44%) with Rhipicephalus sanguineus (s.l.) (0.27%) as the least occurring species. Total nucleic acid from the tick pools was screened for pathogens based on the nucleoprotein gene region in the S segment of the Crimean-Congo haemorrhagic fever virus (CCHFV) genome, the 295-bp fragment of the transposase gene of the Coxiella burnetii IS1111a element, the 560 bp segment of the ssrRNA gene of Babesia and Theileria, the 345 bp fragment of the Ehrlichia genus 16SrRNA gene and the rOmpA gene (OmpA) of Rickettsia. From the 52 tick pools screened, 40 (76.92%) were found positive for pathogen DNA. The pathogens identified were Rickettsia africae (69.23%), Rickettsia aeschlimannii (7.69%), C. burnetii (5.77%), uncultured Ehrlichia sp. (5.77%), Candidatus Midichloria mitochondrii (3.85%) and CCHFV (3.85%). A significant association was observed among A. variegatum, Hyalomma rufipes, Hyalomma truncatum and occurring tick-borne pathogens R. africae, R. aeschlimannii and uncultured Ehrlichia sp. (p < 0.001). CONCLUSION: The findings show the occurrence of zoonotic pathogens, suggesting an increased risk of infections among the abattoir workers. There is a need to adopt control measures within the abattoirs to prevent pathogen spread.

Spatial and temporal variation of five different pathogens and symbionts in Ixodes ricinus nymphs in the Netherlands.

The incidence of diseases caused by pathogens transmitted by the tick Ixodes ricinus vary over time and space through incompletely understood mechanisms. An important determinant of the disease risk is the density of infected ticks, which is the infection prevalence times the density of questing ticks. We therefore investigated the spatial and temporal variation of four pathogens and one of the most abundant symbionts in Ixodes ricinus in questing nymphs over four years of monthly collections in 12 locations in the Netherlands. The infection prevalence of all microbes showed markedly different patterns with significant spatial variation for Borrelia burgdorferi (s.l.), Neoehrlichia mikurensis, Rickettsia helvetica, and Midichloria mitochondrii, significant seasonal variation of B. burgdorferi (s.l.), N. mikurensis, and M. mitochondrii and a significant interannual variation of R. helvetica. Despite its ubiquitous presence, no spatio-temporal variation was observed for the infection prevalence of B. miyamotoi. The variation in infection prevalence was generally smaller than the variation in the density of nymphs, which fluctuated substantially both seasonally and between locations. This means that the variation in the densities of infected nymphs for all pathogens was mostly the result of the variation in densities of nymphs. We also investigated whether there were positive or negative associations between the symbionts, and more specifically whether ticks infected with vertically transmitted symbionts like M. mitochondrii and R. helvetica, have a higher prevalence of horizontally transmitted symbionts, such as B. burgdorferi (s.l.) and N. mikurensis. We indeed found a clear positive association between M. mitochondrii and B. burgdorferi (s.l.). The positive association between R. helvetica and B. burgdorferi (s.l.) was less clear and was only shown in two locations. Additionally, we found a clear positive association between B. burgdorferi (s.l.) and N. mikurensis, which are both transmitted by rodents. Our longitudinal study indicated strong between-location variation, some seasonal patterns and hardly any differences between years for most symbionts. Positive associations between symbionts were observed, suggesting that infection with a (vertically transmitted) symbiont may influence the probability of infection with other symbionts, or that there is a common underlying mechanism (e.g. feeding on rodents).

Administration of Corticosteroids for Prompt Suppression of Cytokine Storm in Severe Cases of Japanese Spotted Fever.

Japanese spotted fever (JSF) is a tick-borne disease caused by Rickettsia japonicaand primarily affects the warmer coastal areas of Japan. Early treatment with tetracycline antibiotics is crucial to prevent severe complications, such as pneumonia, meningitis, disseminated intravascular coagulation (DIC), and systemic inflammatory response syndrome. An 83-year-old man with hypertension, chronic kidney disease, and hyperuricemia presented with DIC and subsequently developed septic shock. Polymerase chain reaction confirmed JSF caused by R. japonica. Initial treatment with ceftriaxone was ineffective, leading to a switch to intravenous minocycline and levofloxacin. Considering the high levels of C-reactive protein, procalcitonin, ferritin, and soluble interleukin-2 receptor, intravenous hydrocortisone (200 mg/day) was administered to control the cytokine storm. On day 4, the patient's condition improved significantly, with increased blood pressure, reduced DIC markers, and decreased levels of inflammatory cytokines, including interleukin-6 and tumor necrosis factor-α. The patient's recovery continued, and he was transferred to a chronic care hospital. Severe JSF cases are primarily driven by a cytokine storm caused by an excessive immune response. Early administration of corticosteroids along with antibiotics effectively suppressed the cytokine storm in this case. Reports have shown mixed results, indicating the need for further research to determine the optimal type, dosage, and duration of corticosteroid treatment.

[First autochthonous case of spotted fever associated with the Reserva Ecológica Costanera Sur, Buenos Aires City]. / Primer caso autóctono de fiebre manchada asociado a la Reserva Ecológica Costanera Sur, Ciudad Autónoma de Buenos Aires.

The first autochthonous case of rickettsiosis is reported here. The case occurred in the Costanera Sur Ecological Reserve, a protected area of the City of Buenos Aires, in August 2022, where 4 species of ticks were found, namely Amblyomma aureolatum, Ixodes auritulus sensu lato, Rhipicephalus sanguineus sensu stricto and Amblyomma triste. The epidemiological, ecological, clinical and laboratory aspects that allowed timely diagnosis and appropriate treatment are also described.

A Mini-Review of Diagnostic Methods for the Antigen and Antibody Detection of Rocky Mountain and Brazilian Spotted Fever.

Rocky Mountain or Brazilian spotted fever, caused by Rickettsia rickettsii, is a fulminant, seasonal, and neglected disease that occurs in focal points of North America and South America. Its rapid detection is essential for the better prognosis and survival rate of infected individuals. However, disease diagnosis still faces challenges as the accuracy of many of the available laboratory tests fluctuates. This review aimed to analyze methods for antibody or antigen detection, their gaps, and their evolution over time. A search was conducted to find all studies in the Pubmed database that described the antibody or antigen detection of R. rickettsii infections. Initially, a total of 403 articles were screened. Of these articles, only 17 fulfilled the pre-established inclusion criteria and were selected. Among the different methods applied, the IFA technique was the one most frequently found in the studies. However, it presented varied results such as a low specificity when using the indirect method. Other techniques, such as ELISA and immunohistochemistry, were also found, although in smaller numbers and with their own limitations. Although some studies showed promising results, there is a pressing need to find new techniques to develop a rapid and effective diagnosis of R. rickettssi infection.

Molecular Identification of Spotted Fever Group Rickettsiae in Ticks in the Republic of Korea.

The Rickettsia species transmitted by ticks are mostly classified within the spotted fever group rickettsiae (SFGR), which causes tick-borne rickettsiosis. Although efforts have been made to investigate their prevalence in the Republic of Korea (ROK), research has been limited to certain areas. Furthermore, the pooling method for ticks does not fully reflect the exact infection rate. Therefore, we aimed to perform molecular identification of SFGR in ticks to elucidate the current prevalence of tick-borne rickettsiosis in the ROK. The SFGR of ticks was identified using polymerase chain reaction targeting the 17 kDa antigen, ompA, and gltA, followed by sequencing for species identification and phylogenetic analysis. In total, 302 ticks belonging to four species (Haemaphysalis flava, H. longicornis, Ixodes nipponensis, and Amblyomma testudinarium) were collected between April and November 2022. The overall SFGR infection rate was 26.8% (81/302 patients). Both adult and nymphal ticks and the SFGR infection rate increased during April-May, reaching their peaks in June, followed by a marked decline in August and July, respectively. Phylogenetic analysis revealed three species (R. monacensis, R. heilongjiangensis, and Candidatus R. jingxinensis) of SFGR. Thus, our results emphasize the importance of tick surveys for the prevention and management of tick-borne rickettsiosis.

Discovery of a novel spotted fever group Rickettsia, "Candidatus Rickettsia kedanie," in unfed larval chigger mites, Leptotrombidium scutellare.

Spotted fever group (SFG) rickettsia, the causative agent of SFG rickettsiosis, is predominantly carried by ticks, whereas Orientia tsutusgamushi, the causative agent of scrub typhus, is primarily transmitted by chigger mites in Japan. In this study, we attempted to isolate intracellular eubacteria from Leptotrombidium scutellare, a major vector of O. tsutsugamushi; moreover, we isolated an SFG rickettsia using a mosquito-derived cell line. Draft genome sequences of this unique isolate, by applying criteria for species delimitation, classified this isolate as a novel strain, proposed as "Rickettsia kedanie." Further genetic analysis identified conserved virulence factors, and the isolate successfully propagated in mammalian cells, suggesting its ability to cause diseases in humans. The presence of SFG rickettsia in unfed larvae implies potential dual-pathogen carriage and reflects a symbiotic relationship similar to that between the mites and O. tsutsugamushi, indicating possibility of its transovarial transmission from female adults. Furthermore, conserved genomic similarity of the novel isolate to known SFG rickettsia suggests potential multiple hosts, including chiggers and ticks. In the natural environment, ticks, chigger mites, and wild animals may carry new isolates, complicating the infection cycle and increasing the transmission risks to humans. This discovery challenges the conventional association of SFG rickettsia with ticks, emphasizing its implications for research and disease control. However, this study was confined to a particular species of chigger mites and geographic area, underscoring the necessity for additional studies to comprehend the ecological dynamics, host interactions, and health implications linked to this newly identified SFG rickettsia.

Japanese spotted fever complicated with pleural effusion in Zhejiang province, China: a case report and literature review.

INTRODUCTION: Japanese spotted fever (JSF) mainly occurs in Japan; however, it has been increasingly reported in China. JSF is typically characterized by fever, rash, and eschar, in addition to non-specific symptoms. Yet, reports on the pulmonary indicators in JSF are limited. Herein, we report an unusual case of JSF associated with pleural effusion and pneumonia, in which the pathogen was identified via blood next-generation sequencing (NGS). CASE PRESENTATION: We report a case of a 33-year-old woman who presented with fever for five days, rash for two days, and myalgia, fatigue, and edema for one day. She had recently been on vacation when an unknown insect bit her. The doctors at the local primary hospital considered a bacterial infection and administered dexamethasone, ceftriaxone, indomethacin, and anti-allergy agents, but the symptoms persisted. A rash without pruritus or pain developed gradually over the entire body and face. We considered rickettsial infection and administered doxycycline and levofloxacin. Metagenomic NGS from blood confirmed the presence of Rickettsia japonica (R. japonica). Abdominal computed tomography revealed bilateral pleural effusion with two atelectasis; patchy shadows with blurred edges, and uniform enhancement in both lower lungs. After several days of treatment, the symptoms and laboratory results improved. A literature review of the epidemiology of R. japonica and JSF in China, characteristics of JSF, and related pulmonary changes, and technology to diagnose JSF is provided. CONCLUSIONS: JSF has a variety of symptoms and is becoming increasingly popular in China. Clinical doctors need to identify it carefully.

Rocky Mountain Spotted Fever Mimicking Multisystem Inflammatory Syndrome in Hospitalized Children, Sonora, Mexico.

We describe 5 children who had Rocky Mountain spotted fever (RMSF) and manifested clinical symptoms similar to multisystem inflammatory syndrome in Sonora, Mexico, where RMSF is hyperendemic. Physicians should consider RMSF in differential diagnoses of hospitalized patients with multisystem inflammatory syndrome to prevent illness and death caused by rickettsial disease.

A Case Series on Spotted Fever and Typhus Fever Seropositivity at National Center for Disease Control and Epidemiological Perspective.

Background: The rickettsioses, except for typhus fever and scrub typhus (ST), were not really recognized as distinct clinical entities until the early 20th century. Only when specific rickettsial serologic testing was introduced in the 1940s could the precise etiologies of various rickettsial diseases (RDs) be determined with certainty. Although ST is a well- recognized zoonotic disease entity, but non-scrub typhus rickettsial infection like spotted fever group and typhus group are not well studied in India and are still underestimated. Methods: We report cases who had shown seropositivity of spotted fever and typhus fever RD in IgM and IgG ELISA whose samples were referred from various hospitals of Delhi/National Capital Region in which clinicians had strong suspicion of rickettsiosis other than ST or Weil-Felix test found positive for any of the OX2, 19, and K antigens. Results: We reported 18 cases of SFG and TGRD with mostly cases presented with fever followed by hepato-intestinal symptoms. Conclusion: The vast variability and nonspecific presentation of rickettsiosis in spotted and typhus fever at times have often made it difficult to diagnose clinically. Prompt antibiotic therapy shortens the course of the disease, lowers the risk of complications, and in turn, reduces morbidity and mortality owing to RDs. There is a distinct need for physicians and health care workers at all levels of care in India to be aware of the clinical features, available diagnostic tests and their interpretation, and the therapy for these infections.

Case report: Multiple organ failure caused by Japanese spotted fever.

A 71-year-old male had disseminated multiple organ dysfunction syndrome (MODS). Following treatment with cefotaxime and piperacillin-tazobactam, his symptoms have worsened instead. Multiple organ failure caused by Japanese Spotted Fever (JSF) was diagnosed based on metagenomic next-generation sequencing (mNGS), we rapidly treated the patient with doxycycline. Thereafter, his symptoms gradually improved. In this report, we emphasized the importance of rapid microbial diagnostic tools and the early use of tetracyclines for the treatment of JSF.

Rocky Mountain spotted fever contracted along a Canadian road trip: A case report.

Rocky Mountain spotted fever, a potentially fatal tick-borne disease thought to be confined to specific climates and geographic locations, is expanding its reach due to climate change. This is demonstrated by a 73-year-old woman who contracted Rocky Mountain spotted fever outside endemic areas during travel in Canada. Presenting with fevers, arthralgia, weakness, non-bloody diarrhea, conjunctivitis, mild cough, and a rash, this patient was initially started on moxifloxacin (400 mg PO/day) for suspected pneumonia. Treatment was changed to doxycycline (100 mg PO twice daily for 7 days) after dermatology was consulted, and Rocky Mountain spotted fever was thought to be higher on the differential. Rocky Mountain spotted fever was confirmed, and the patient responded well to antibiotics, improving by discharge. The disease's expansion into previously thought nonendemic areas is thought to be linked to milder winters and more extreme dry summers, facilitating pathogen development and tick lineage expansion.

Three cases of African tick bite fever diagnosed in Quebec City: A case series.

African tick bite fever is a rickettsiosis of the spotted fever group that is endemic to sub-Saharan Africa and the Caribbean. It is characterized by eschars at the inoculation sites and a maculopapular rash which may be purpuric. We describe three cases that were diagnosed in Quebec City.