Increased detection of rickettsialpox in a New York City hospital following the anthrax outbreak of 2001: use of immunohistochemistry for the rapid confirmation of cases in an era of bioterrorism

An unusual outbreak of dermatitis due to rodent mite infestation in an acute-care hospital

We report an outbreak of dermatitis associated with Ornithonysus bacoti and Liponyssoides sanguineus infestation in an acute ambulatory care setting. Healthcare workers developed dermatitis prior to the identification of the outbreak. A collaborative team effort resulted in complete eradication.

Proteomic analysis of Rickettsia akari proposes a 44 kDa-OMP as a potential biomarker for Rickettsialpox diagnosis

Background

Rickettsialpox is a febrile illness caused by the mite-borne pathogen Rickettsia akari. Several cases of this disease are reported worldwide annually. Nevertheless, the relationship between the immunogenicity of R. akari and disease development is still poorly understood. Thus, misdiagnosis is frequent. Our study is aiming to identify immunogenic proteins that may improve disease recognition and enhance subsequent treatment. To achieve this goal, two proteomics methodologies were applied, followed by immunoblot confirmation.

Results

Three hundred and sixteen unique proteins were identified in the whole-cell extract of R. akari. The most represented protein groups were found to be those involved in translation, post-translational modifications, energy production, and cell wall development. A significant number of proteins belonged to amino acid transport and intracellular trafficking. Also, some proteins affecting the virulence were detected. In silico analysis of membrane enriched proteins revealed 25 putative outer membrane proteins containing beta-barrel structure and 11 proteins having a secretion signal peptide sequence. Using rabbit and human sera, various immunoreactive proteins were identified from which the 44 kDa uncharacterized protein (A8GP63) has demonstrated a unique detection capability. It positively distinguished the sera of patients with Rickettsialpox from other rickettsiae positive human sera.

Conclusion

Our proteomic analysis certainly contributed to the lack of knowledge of R. akari pathogenesis. The result obtained may also serve as a guideline for a more accurate diagnosis of rickettsial diseases. The identified 44 kDa uncharacterized protein can be certainly used as a unique marker of rickettsialpox or as a target molecule for the development of more effective treatment.

An apparent, locally acquired case of rickettsialpox (Rickettsia akari) in Ontario, Canada

Rickettsialpox, caused by Rickettsia akari, is a spotted fever group rickettsiae transmitted to humans through the bite of the house mouse mite (Liponyssoides sanguineus). Worldwide, rickettsialpox is most commonly associated with exposure to rodents in urban environments. Here, we present the case of a 47-year-old woman from Brantford, Ontario, with fever, eschar on the right leg, expanding erythema, and right groin lymphadenopathy. Early in infection, R. akari serology was negative (IgG <1:64), but convalescent titre increased to 1:1,024. The patient did not travel outside of Ontario in the previous year. She denied any rodent or arthropod exposures in her home, but recently visited a friend's home infested with bats and mice. The patient was afebrile after treatment with doxycycline, with resolution of most clinical and laboratory findings in 5 days. This is the first rickettsialpox case reported in Canada and highlights the importance of obtaining convalescent serology to assist in the diagnosis of rickettsial infection.

Investigating the histopathological findings and immunolocalization of rickettsialpox infection in skin biopsies: A case series and review of the literature

BACKGROUND

Recognition of rickettsialpox infection on skin biopsy can be challenging. The histopathology is non-specific and inconsistently described. We assess classic histopathologic features in confirmed cases and review the literature.

METHODS

We searched for cases of "rickettsialpox" diagnosed between 2006 and 2018 with positive immunostaining for Spotted Fever Group Rickettsia species. Original slides were evaluated for vacuolar alterations, granulomatous inflammation, vasculitis, necrosis, fibrin thrombi, microvesiculation, papillary dermal edema, and extravasated red blood cells. All biopsies were stained for CD3, CD20, CD68, and myeloperoxidase.

RESULTS

Six biopsy specimens were compiled, three of which were sampled from vesiculopapules, one from a maculopapule, and two from eschars. Vacuolar alterations and vasculitis were present in all specimens (6/6; 100%). Granulomatous inflammation was present in five specimens (5/6; 83.3%). Fibrin thrombi and red blood cells were seen in 3/6 (50%) of specimens. The eschars showed necrosis of the epidermis and superficial dermis (2/6, 33.3%). Only one specimen showed intraepidermal vesiculation and papillary dermal edema (1/6; 16.7%). All six specimens showed perivascular infiltration with CD3+ T-cells, and low amounts of CD20+ B-cells and neutrophils. Five of the six specimens (83.3%) showed significant levels of CD68+ histiocytes.

CONCLUSION

The histopathology of rickettsialpox infection is septic lymphocytic and granulomatous vasculitis.

Rickettsialpox in a Pediatric Patient

Rickettsialpox is a rare vector-borne rickettsiosis that manifests in hosts living in urban populations, particularly in New York City. The following is a case discussion of a 12-year-old girl with history of fever and right-ankle swelling. She was initially evaluated and treated for cellulitis. She later developed a maculopapular rash completing the classic triad for rickettsialpox: black eschar, papular rash, and fever. Her convalescent rickettsial titers returned positive, confirming the diagnosis of rickettsialpox.

Comparison of Preferred Bite Sites Between Mites and Ticks on Humans in Korea

Identification of mite and tick bite sites provides important clinical information. The predominant mite species in Korea associated with scrub typhus are Leptotrombidium pallidum and Leptotrombidium scutellare The most abundant tick species is Haemaphysalis longicornis To date, there has been no comparative study on preferred bite sites between mites and ticks in humans. This study included a review of medical records and a field study. For mite bite sites, eschars were checked on 506 patients with scrub typhus, confirmed by indirect immunofluorescence assay or nested polymerase chain reaction on the 56-kDa type-specific antigen gene of Orientia tsutsugamushi Tick bite sites were identified and marked on a diagram for 91 patients who experienced tick bites within the previous year through a field epidemiological investigation. The mite and tick bite sites in Koreans were compared. The most frequently observed mite bite sites were the anterior chest, including the axillae (29.1%) and the abdominal region, including the inguinal area (26.1%). Tick bite sites were most frequent on the lower extremities (33.0%), followed by the abdominal region, including the inguinal area (26.4%), and upper extremities (26.4%). The distribution was significantly different between mite and tick bite sites (P < 0.001). There was a statistically significant difference in the mite bite (P = 0.001), but not tick bite sites (P = 0.985), between men and women. This is the first report on the differences between tick and mite bite sites, and may help clinicians reach a rapid diagnosis of mite- or tick-borne infection.

Zoonotic and Vector-Borne Infections Among Urban Homeless and Marginalized People in the United States and Europe, 1990-2014

INTRODUCTION

In high-income countries, homeless individuals in urban areas often live in crowded conditions with limited sanitation and personal hygiene. The environment of homelessness in high-income countries may result in intensified exposure to ectoparasites and urban wildlife, which can transmit infections. To date, there have been no systematic evaluations of the published literature to assess vector-borne and zoonotic disease risk to these populations.

OBJECTIVES

The primary objectives of this study were to identify diversity, prevalence, and risk factors for vector-borne and zoonotic infections among people experiencing homelessness and extreme poverty in urban areas of high-income countries.

METHODS

We conducted a systematic review and narrative synthesis of published epidemiologic studies of zoonotic and vector-borne infections among urban homeless and very poor people in the United States and Europe from 1990 to 2014.

RESULTS

Thirty-one observational studies and 14 case studies were identified (n = 45). Seroprevalence to the human louse-borne pathogen Bartonella quintana (seroprevalence range: 0-37.5%) was identified most frequently, with clinical disease specifically observed among HIV-positive individuals. Seropositivity to Bartonella henselae (range: 0-10.3%) and Rickettsia akari (range: 0-16.2%) was noted in multiple studies. Serological evidence of exposure to Rickettsia typhi, Rickettsia prowazekii, Bartonella elizabethae, West Nile virus, Borellia recurrentis, lymphocytic choriomeningitis virus, Wohlfartiimonas chitiniclastica, Seoul hantavirus (SEOV), and Leptospira species was also identified in published studies, with SEOV associated with chronic renal disease later in life. HIV infection, injection drug use, and heavy drinking were noted across multiple studies as risk factors for infection with vector-borne and zoonotic pathogens.

CONCLUSIONS

B. quintana was the most frequently reported vector-borne infection identified in our article. Delousing efforts and active surveillance among HIV-positive individuals, who are at elevated risk of complication from B. quintana infection, are advised to reduce morbidity. Given documented exposure to rodent-borne zoonoses among urban homeless and marginalized people, reducing human contact with rodents remains an important public health priority.

Immunohistochemistry in the diagnosis of cutaneous bacterial infections

The identification of pathogens is of vital importance for the adequate treatment of infections. During the past 2 decades, the approach to histopathologic diagnosis has been dramatically transformed by immunohistochemistry (IHC) specifically in the diagnosis and classification of tumors and more recently in the diagnosis of infectious diseases in tissue samples. The main goals of this article were to: (1) identify by IHC the cutaneous structures where bacterial pathogens are expressed in the course of infection, (2) identify the specific cells in which bacterial pathogens are expressed in positive cases, and (3) describe the pattern of distribution of the bacterial antigens within these cells (nuclear, cytoplasmatic, or membranous). This article is an up-to-date overview of the potential uses and limitations of IHC in the histopathologic diagnosis of cutaneous bacterial infections. In conclusion, IHC is especially useful in the identification of microorganisms that are present in low numbers, stain poorly, are fastidious to grow, culture is not possible, or exhibit an atypical morphology.

Detection of Rickettsia rickettsii, Rickettsia parkeri, and Rickettsia akari in skin biopsy specimens using a multiplex real-time polymerase chain reaction assay

BACKGROUND

Rickettsia rickettsii, Rickettsia parkeri, and Rickettsia akari are the most common causes of spotted fever group rickettsioses indigenous to the United States. Infected patients characteristically present with a maculopapular rash, often accompanied by an inoculation eschar. Skin biopsy specimens are often obtained from these lesions for diagnostic evaluation. However, a species-specific diagnosis is achieved infrequently from pathologic specimens because immunohistochemical stains do not differentiate among the causative agents of spotted fever group rickettsiae, and existing polymerase chain reaction (PCR) assays generally target large gene segments that may be difficult or impossible to obtain from formalin-fixed tissues.

METHODS

This work describes the development and evaluation of a multiplex real-time PCR assay for the detection of these 3 Rickettsia species from formalin-fixed, paraffin-embedded (FFPE) skin biopsy specimens.

RESULTS

The multiplex PCR assay was specific at discriminating each species from FFPE controls of unrelated bacterial, viral, protozoan, and fungal pathogens that cause skin lesions, as well as other closely related spotted fever group Rickettsia species.

CONCLUSIONS

This multiplex real-time PCR demonstrates greater sensitivity than nested PCR assays in FFPE tissues and provides an effective method to specifically identify cases of Rocky Mountain spotted fever, rickettsialpox, and R. parkeri rickettsiosis by using skin biopsy specimens.

Systematic review of surveillance systems for emerging zoonoses

Evaluations of emerging zoonoses surveillance systems are rarely found in the published literature, making it difficult for decision-makers to choose the best surveillance initiatives.

Pre-spillover prevention of emerging zoonotic diseases: what are the targets and what are the tools?

The uneven standards of surveillance, human- or animal-based, for zoonotic diseases or pathogens maintained and transmitted by wildlife H(R)s, or even domestic species, is a global problem, readily apparent even within the United States, where investment in public health, including surveillance systems, has a long and enviable history. As of 2006, there appears to be little scientific, social, or political consensus that animal-based surveillance for zoonoses merits investment in international infrastructure, other than the fledgling efforts with avian influenza, or targeted nontraditional avenues of surveillance and research. National institutions charged with strategic planning for emerging diseases or intentional releases of zoonotic agents have emphasized improving diagnostic capabilities for detecting human infections, modifying the immune status of human or domestic animals through vaccines, producing better antiviral or antibacterial drugs, and enhancing human-based surveillance as an early warning system. With the possible exception of extensive human vaccination, each of these approaches target post-spillover events and none of these avenues of research will have the slightest impact on reducing the risk of additional emergence of viruses or other pathogens from wildlife. Novel schemes of preventing spillover of human pathogens from animal H(R)s can only spring from improving our understanding of the ecological context and biological interactions of pathogen maintenance among H(R)s. Although the benefit derived from investments to improve surveillance and knowledge of zoonotic pathogens circulating among wildlife H(R) populations is uncertain, our experience with HIV and the looming threat of pandemic avian influenza A inform us of the outcomes we can expect by relying on detection of post-spillover events among sentinel humans.

Cutaneous Vasculitis Update: Diagnostic Criteria, Classification, Epidemiology, Etiology, Pathogenesis, Evaluation and Prognosis

Vasculitis, inflammation of the vessel wall, can result in mural destruction with hemorrhage, aneurysm formation, and infarction, or intimal-medial hyperplasia and subsequent stenosis leading to tissue ischemia. The skin, in part due to its large vascular bed, exposure to cold temperatures, and frequent presence of stasis, is involved in many distinct as well as un-named vasculitic syndromes that vary from localized and self-limited to generalized and life-threatening with multi-organ disease. To exclude mimics of vasculitis, diagnosis of cutaneous vasculitis requires biopsy confirmation where its acute signs (fibrinoid necrosis), chronic signs (endarteritis obliterans), or past signs (acellular scar of healed arteritis) must be recognized and presence of extravascular findings such as patterned fibrosis or collagenolytic granulomas noted. Although vasculitis can be classified by etiology, many cases have no identifiable cause, and a single etiologic agent can elicit several distinct clinicopathologic expressions of vasculitis. Therefore, the classification of cutaneous vasculitis is best approached morphologically by determining vessel size and principal inflammatory response. These histologic patterns roughly correlate with pathogenic mechanisms that, when coupled with direct immunofluorescent examination, anti-neutrophil cytoplasmic antibody (ANCA) status, and findings from work-up for systemic disease, allow for specific diagnosis, and ultimately, more effective therapy. Herein, we review cutaneous vasculitis focusing on diagnostic criteria, classification, epidemiology, etiology, pathogenesis, and evaluation of the cutaneous vasculitis patient.

Rickettsial skin disease: uncommon presentations

Rickettsioses occurring worldwide show a significant morbidity and mortality when not properly treated. Early diagnosis is mandatory for better outcome. Clinical symptoms and patient's history are essential, but uncommon presentation of these arthropod-borne diseases may be a challenge.

Rickettsialpox: report of three cases and a review

Rickettsialpox is a rare mite-borne rickettsiosis that is encountered in urban populations in the eastern United States and throughout the world. It is characterized clinically by an eschar, fever, and a papulovesicular eruption. Both of these cutaneous manifestations may be mimicked by infectious diseases that have been designated as bioterrorist agents by the United States Centers for Diseases Control and Prevention: the former by anthrax, and the latter by smallpox. It is thus important for clinicians to be familiar with rickettsialpox. We report 3 cases and review the epidemiology, clinical and laboratory findings, differential diagnosis, and management of this disease.

A call to arms-the role of the dermatologist as front line responder

As the risk of bioterrorism becomes an increasingly significant issue in the United States and the world, dermatologists have found themselves as partners or front line participants in the effort to prepare for and respond to such a threat. In what was previously an unfamiliar part of practice for most dermatologists, bioterrorism has required that providers familiarize themselves with the pathophysiology, clinical presentation, diagnosis,and management of diseases from agents that could potentially be used.