Emergence of Bartonella quintana infection among homeless persons

Bartonella quintana Endocarditis: A Systematic Review of Individual Cases

BACKGROUND

Bartonella quintana is a louse-borne bacterium that remains a neglected cause of endocarditis in low-resource settings. Our understanding of risk factors, clinical manifestations, and treatment of B. quintana endocarditis are biased by older studies from high-income countries.

METHODS

We searched Pubmed Central, Medline, Scopus, Embase, EBSCO (CABI) Global Health, Web of Science and international trial registers for articles published before March 2023 with terms related to Bartonella quintana endocarditis. We included articles containing case-level information on B. quintana endocarditis and extracted data related to patient demographics, clinical features, diagnostic testing, treatment, and outcome.

RESULTS

A total of 975 records were identified, of which 569 duplicates were removed prior to screening. In total, 84 articles were eligible for inclusion, describing a total of 167 cases. Infections were acquired in 40 different countries; 62 cases (37.1%) were acquired in low- and middle-income countries (LMICs). Disproportionately more female and pediatric patients were from LMICs. More patients presented with heart failure (n = 70/167 [41.9%]) than fever (n = 65/167 [38.9%]). Mean time from symptom onset to presentation was 5.1 months. Also, 25.7% of cases (n = 43/167) were associated with embolization, most commonly to the spleen and brain; 65.5% of antimicrobial regimens included doxycycline. The vast majority of cases underwent valve replacement surgery (n = 154/167, [98.0%]). Overall case fatality rate was 9.6% (n = 16/167).

CONCLUSIONS

B. quintana endocarditis has a global distribution, and long delays between symptom onset and presentation frequently occur. Improved clinician education and diagnostic capacity are needed to screen at-risk populations and identify infection before endocarditis develops.

Hidden Burden of Bartonella quintana on the African Continent: Should the Bacterial Infection Be Considered a Neglected Tropical Disease?

Bartonella quintana is a louse-borne gram-negative bacillus that remains a poorly characterized cause of bacteremia, fever, and infective endocarditis. Due to the link with pediculosis, B quintana transmission is tied to poverty, conflict, overcrowding, and inadequate water access to maintain personal hygiene. Although these risk factors may be present globally, we argue that a substantial burden of undocumented B quintana infection occurs in Africa due to the high prevalence of these risk factors. Here, we describe the neglected burden of B quintana infection, endocarditis, and vector positivity in Africa and evaluate whether B quintana meets criteria to be considered a neglected tropical disease according to the World Health Organization.

Detection of Bartonella quintana (Hyphomicrobiales: Bartonellaceae) Among Day Laborers in Osaka, Japan, 2009-2010

Bartonella quintana is a gram-negative bacterium causing trench fever, an illness historically acquired by soldiers during World War I. More recently, outbreaks of trench fever have been reported in those experiencing homelessness in the United States, France, Russia, and Tokyo, as well as in children in Nepal and persons in Ethiopia. Reports of B. quintana infection outside of Tokyo are rare in Japan. The aim of this study was to examine body lice and blood obtained from people staying in shelters in Osaka (2009-2010) for B. quintana via polymerase chain reaction and enzyme-linked immunosorbent assays. Day laborers were defined as homeless individuals and shelter residents in this study. We detected genes of B. quintana in body lice by PCR and antibodies against B. quintana. The positive rate of B. quintana genes was 6/10 (60%) in body lice and the seroprevalence (IgG) of B. quintana was 4/10 (40%). This demonstrates that trench fever was endemic in people staying in shelters in Osaka in 2009-2010.

Lice and lice-borne diseases in humans in Africa: a narrative review

Lice are host-specific insects. Human lice include Pediculus humanus humanus (body lice) which are known to be vectors of serious human bacterial infectious diseases including epidemic typhus, relapsing fever, trench fever and plague; Pediculus humanus capitis (head lice) that frequently affect children; and Pthirus pubis, commonly known as crab lice. In Africa, human infections transmitted by lice remained poorly known and therefore, underestimated, perhaps due to the lack of diagnostic tools and professional knowledge. In this paper we review current knowledge of the microorganisms identified in human lice in the continent of Africa, in order to alert health professionals to the importance of recognising the risk of lice-related diseases.

Detection of Bartonella quintana infection among the Homeless Population in Tokyo, Japan, from 2013-2015

Several outbreaks of trench fever caused by Bartonella quintana, occurred in soldiers during World Wars I and II. Although the number of trench fever cases has been decreasing worldwide, the disease has been reported among the homeless population in both developing and developed countries. The current prevalence of B. quintana infection in Japan is unclear. We collected blood and body louse (Pediculus humanus humanus) samples from homeless inpatients who had body lice at the time of emergency hospitalization in Tokyo from January 2013 to March 2015. Patients were tested for B. quintana infections using culture method, polymerase chain reaction, and indirect immunofluorescence assay (IFA). Among the 29 patients tested, the presence of Bartonella spp. was confirmed by genomic sequencing of DNA extracted from the samples from 2 patients (blood culture performed for 13 out of 15 patients), and from body louse samples of 20 patients (69%). Immunoglobulin G against B. quintana was detected in 10 patients (34.5%) at a cut-off titer of 1:256 in IFA. B. quintana infection was detected in samples obtained between 2013 and 2015 in Tokyo and needs to be on the list of differential diagnoses performed for febrile homeless individuals.

Molecular investigation and genetic diversity of Pediculus and Pthirus lice in France

BACKGROUND

Humans are parasitized by three types of lice: body, head and pubic lice. As their common names imply, each type colonizes a specific region of the body. The body louse is the only recognized disease vector. However, an increasing awareness of head lice as a vector has emerged recently whereas the status of pubic lice as a vector is not known since it has received little attention.

METHODS

Here, we assessed the occurrence of bacterial pathogens in 107 body lice, 33 head lice and 63 pubic lice from Marseille and Bobigny (France) using molecular methods.

RESULTS

Results show that all body lice samples belonged to the cytb Clade A whereas head lice samples belonged to Clades A and B. DNA of Bartonella quintana was detected in 7.5% of body lice samples and, for the first time to our knowledge, in 3.1% of pubic lice samples. Coxiella burnetii, which is not usually associated with transmission by louse, was detected in 3.7% of body lice samples and 3% of head lice samples. To the best of our knowledge, this is the first report of C. burnetii in Pediculus lice infesting humans in France. Acinetobacter DNA was detected in 21.5% of body lice samples, 6% of head lice samples and 9.5% of pubic lice samples. Five species were identified with A. baumannii being the most prevalent.

CONCLUSIONS

Our study is the first to report the presence of B. quintana in pubic lice. This is also the first report of the presence of DNA of C. burnetii in body lice and head lice in France. Further efforts on the vectorial role of human lice are needed, most importantly the role of pubic lice as a disease vector should be further investigated.

Bartonella spp. - a chance to establish One Health concepts in veterinary and human medicine

Infectious diseases remain a remarkable health threat for humans and animals. In the past, the epidemiology, etiology and pathology of infectious agents affecting humans and animals have mostly been investigated in separate studies. However, it is evident, that combined approaches are needed to understand geographical distribution, transmission and infection biology of “zoonotic agents”. The genus Bartonella represents a congenial example of the synergistic benefits that can arise from such combined approaches: Bartonella spp. infect a broad variety of animals, are linked with a constantly increasing number of human diseases and are transmitted via arthropod vectors. As a result, the genus Bartonella is predestined to play a pivotal role in establishing a One Health concept combining veterinary and human medicine.

Bartonella species and their ectoparasites: selective host adaptation or strain selection between the vector and the mammalian host?

A wide range of blood-sucking arthropods have either been confirmed or are suspected as important vectors in Bartonella transmission to mammals, including humans. Overall, it appears that the diversity of Bartonella species DNA identified in ectoparasites is much broader than the species detected in their mammalian hosts, suggesting a mechanism of adaptation of Bartonella species to their host-vector ecosystem. However, these mechanisms leading to the fitness between the vectors and their hosts still need to be investigated.

Arthropod-borne diseases associated with political and social disorder

The living conditions and the crowded situations of the homeless, war refugees, or victims of a natural disaster provide ideal conditions for the spread of lice, fleas, ticks, flies and mites. The consequence of arthropod infestation in these situations is underestimated. Along with louse-borne infections such as typhus, trench fever, and relapsing fever, the relationship between Acinetobacter spp.-infected lice and bacteremia in the homeless is not clear. Murine typhus, tungiasis, and myiasis are likely underestimated, and there has been a reemergence of bed bugs. Attempted eradication of the body louse, despite specific measures, has been disappointing, and infections with Bartonella quintana continue to be reported. The efficacy of ivermectin in eradicating the human body louse, although the effect is not sustained, might provide new therapeutic approaches. Arthropod-borne diseases continue to emerge within the deprived population. Public health programs should be engaged rapidly to control these pests and reduce the incidence of these transmissible diseases.

High Bartonella spp. seroprevalence in a Swedish homeless population but no evidence of trench fever

Blood samples and epidemiological data were collected from 50 homeless patients in central Stockholm, Sweden. Sera were analysed for antibodies to B. henselae, B. quintana, B. elizabethae and B. grahamii. Whole blood was cultured and used as substrate for a newly developed quantitative real time polymerase chain reaction (QPCR) specifically targeting Bartonella spp. DNA. 61 matched blood donor sera were used as controls. Homeless patients were significantly more often seropositive to Bartonella spp. than controls (OR 7.58 (3.30-17.39), p<0.05). Reactivity to the B. elizabethae antigen was dominating, although the difference between patients and controls was most significant in seroreactivity to the B. henselae antigen. There was no evidence of an ongoing B. quintana epidemic. The absence of louse infestation could explain the lack of B. quintana bacteraemia and the failure to amplify Bartonella DNA.

Emerging and reemerging diseases: a historical perspective

Summary: Between mid‐century and 1992, there was a consensus that the battle against infectious diseases had been won, and the Surgeon General announced that it was time to close the book. Experience with human immunodeficiency virus/acquired immunodeficiency syndrome, the return of cholera to the Americas in 1991, the plague outbreak in India in 1994, and the emergence of Ebola in Zaire in 1995 created awareness of a new vulnerability to epidemics due to population growth, unplanned urbanization, antimicrobial resistance, poverty, societal change, and rapid mass movement of people. The increasing virulence of dengue fever with dengue hemorrhagic fever and dengue shock syndrome disproved the theory of the evolution toward commensalism, and the discovery of the microbial origins of peptic ulcer demonstrated the reach of infectious diseases. The Institute of Medicine coined the term ‘emerging and reemerging diseases’ to explain that the world had entered an era in which the vulnerability to epidemics in the United States and globally was greater than ever. The United States and the World Health Organization took devised rapid response systems to monitor and contain disease outbreaks and to develop new weapons against microbes. These mechanisms were tested by severe acute respiratory syndrome in 2003, and a series of practical and conceptual blind spots in preparedness were revealed.

Vector transmission of Bartonella species with emphasis on the potential for tick transmission

Bartonella species are gram-negative bacteria that infect erythrocytes, endothelial cells and macrophages, often leading to persistent blood-borne infections. Because of the ability of various Bartonella species to reside within erythrocytes of a diverse number of animal hosts, there is substantial opportunity for the potential uptake of these blood-borne bacteria by a variety of arthropod vectors that feed on animals and people. Five Bartonella species are transmitted by lice, fleas or sandflies. However, Bartonella DNA has been detected or Bartonella spp. have been cultured from numerous other arthropods. This review discusses Bartonella transmission by sandflies, lice and fleas, the potential for transmission by other vectors, and data supporting transmission by ticks. Polymerase chain reaction (PCR) or culture methods have been used to detect Bartonella in ticks, either questing or host-attached, throughout the world. Case studies and serological or molecular surveys involving humans, cats and canines provide indirect evidence supporting transmission of Bartonella species by ticks. Of potential clinical relevance, many studies have proposed co-transmission of Bartonella with other known tick-borne pathogens. Currently, critically important experimental transmission studies have not been performed for Bartonella transmission by many potential arthropod vectors, including ticks.

Do bartonella infections cause agitation, panic disorder, and treatment-resistant depression?

INTRODUCTION

Bartonella is an emerging infection found in cities, suburbs, and rural locations. Routine national labs offer testing for only 2 species, but at least 9 have been discovered as human infections within the last 15 years. Some authors discuss Bartonella cases having atypical presentations, with serious morbidity considered uncharacteristic of more routine Bartonella infections. Some atypical findings include distortion of vision, abdominal pain, severe liver and spleen tissue abnormalities, thrombocytopenic purpura, bone infection, arthritis, abscesses, heart tissue and heart valve problems. While some articles discuss Bartonella as a cause of neurologic illnesses, psychiatric illnesses have received limited attention. Case reports usually do not focus on psychiatric symptoms and typically only as incidental comorbid findings. In this article, we discuss patients exhibiting new-onset agitation, panic attacks, and treatment-resistant depression, all of which may be attributed to Bartonella.

METHODS

Three patients receiving care in an outpatient clinical setting developed acute onset personality changes and agitation, depression, and panic attacks. They were retrospectively examined for evidence of Bartonella infections. The medical and psychiatric treatment progress of each patient was tracked until both were significantly resolved and the Bartonella was cured.

RESULTS

The patients generally seemed to require higher dosing of antidepressants, benzodiazepines, or antipsychotics in order to function normally. Doses were reduced following antibiotic treatment and as the presumed signs of Bartonella infection remitted. All patients improved significantly following treatment and returned to their previously healthy or near-normal baseline mental health status.

DISCUSSION

New Bartonella species are emerging as human infections. Most do not have antibody or polymerase chain reaction (PCR) diagnostic testing at this time. Manual differential examinations are of unknown utility, due to many factors such as low numbers of infected red blood cells, the small size of the infecting bacteria, uncertainty of current techniques in viewing such small bacteria, and limited experience. As an emerging infection, it is unknown whether Bartonella occurrence in humans worldwide is rare or common, without further information from epidemiology, microbiology, pathology, and treatment outcomes research.

CONCLUSION

Three patients presented with acute psychiatric disorders associated with Bartonella-like signs and symptoms. Each had clear exposure to ticks or fleas and presented with physical symptoms consistent with Bartonella, eg, an enlarged lymph node near an Ixodes tick bite and bacillary angiomatosis found only in Bartonella infections. Laboratory findings and the overall general course of the illnesses seemed consistent with Bartonella infection. The authors are not reporting that these patients offer certain proof of Bartonella infection, but we hope to raise the possibility that patients infected with Bartonella can have a variety of mental health symptoms. Since Bartonella can clearly cause neurologic disorders, we feel the presence of psychiatric disorders is a reasonable expectation.

Arthropod-borne diseases in homeless

Homeless people are particularly exposed to ectoparasite. The living conditions and the crowded shelters provide ideal conditions for the spread of lice, fleas, ticks, and mites. Body lice have long been recognized as human parasites and although typically prevalent in rural communities in upland areas of countries close to the equator, it is now increasingly encountered in developed countries especially in homeless people or inner city economically deprived population. Fleas are widespread but are not adapted to a specific host and may occasionally bite humans. Most common fleas that parasite humans are the cat, the rat, and the human fleas, Ctenocephalides felis, Xenopsylla cheopis, and Pulex irritans, respectively. Ticks belonging to the family Ixodidae, in particular, the genera Dermacentor, Rhipicephalus, and Ixodes, are frequent parasites in humans. Sarcoptes scabiei var. hominis is a mite (Arachnida class) responsible for scabies. It is an obligate parasite of human skin. The hematophagic-biting mite, Liponyssoides sanguineus, is a mite of the rat, mouse, and other domestic rodents but can also bite humans. Finally, the incidence of skin disease secondary to infestation with the human bedbug, Cimex lectularius, has increased recently. Bacteria, such as Wolbacchia spp. have been detected in bedbug. The threat posed by the ectoparasite in homeless is not the ectoparasite themselves but the associated infectious diseases that they may transmit to humans. Except for scabies all these ectoparasites are potential vectors for infectious agents. Three louse-borne diseases are known at this time. Trench fever caused by Bartonella quintana (B. quintana), epidemic typhus caused by Rickettsia prowazekii, and relapsing fever caused by the spirochete Borrelia recurrentis. Fleas transmit plague (Xenopsylla cheopis and Pulex irritans), murine typhus (Xenopsylla cheopis), flea-borne spotted rickettsiosis on account of the recently described species Rickettsia felis (C. felis), and occasionally cat scratch disease on account of Bartonella henselae (C. felis). The role of fleas as potential vector of B. quintana has recently been suggested. Among the hematophagic-biting mites, L. sanguineus, is responsible for the transmission of Rickettsia akari, the etiologic agent of rickettsialpox. Virtually, no data are available on tick-borne disease in this population. This article will deal with epidemiology, diagnosis, prevention, and treatment of these ectoparasite and the infectious diseases they transmit to the homeless people.

First molecular evidence of Bartonella quintana in Pediculus humanus capitis (Phthiraptera: Pediculidae), collected from Nepalese children

Trench fever is a body louse-borne disease caused by Bartonella quintana Brenner. The recent status of louse infestation in Nepalese children is not well known. We collected head and body lice, Pediculus humanus capitis De Geer and Pediculus humanus humanus L., respectively, from 30 children, including 11 cases of double infestation with both head and body lice. Detection of B. quintana in both louse species identified was carried out by polymerase chain reaction (PCR). PCR products with B. quintana DNA sequences were detected in both head and body lice from two children as well as in body lice derived from two other children. These results demonstrate that head lice may also play a role in the transmission of trench fever.

Ectoparasitism and vector-borne diseases in 930 homeless people from Marseilles

Homeless people are particularly exposed to ectoparasites, but their exposure to arthropod-borne diseases has not been evaluated systematically. A medical team of 27 persons (7 nurses, 6 infectious disease residents or fellows, 2 dermatologists, and 12 infectious disease specialists) visited the 2 shelters in Marseilles, France, for 4 consecutive years. Homeless volunteers were interviewed, examined, and received care; and blood was sampled for cell counts and detection of bacteremia, antibodies to louse-borne (Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis), flea-borne (R. typhi, R. felis), mite-borne (R. akari), and tick-borne (R. conorii) bacterial agents. We selected sex- and age-adjusted controls among healthy blood donors. Over 4 years, 930 homeless people were enrolled. Lice were found in 22% and were associated with hypereosinophilia (odds ratio, 5.7; 95% confidence intervals, 1.46-22.15). Twenty-seven patients (3%) with scabies were treated with ivermectin. Bartonella quintana was isolated from blood culture in 50 patients (5.3%), 36 of whom were treated effectively. The number of bacteremic patient increased from 3.4% to 8.4% (p = 0.02) over the 4 years of the study. We detected a higher seroprevalence to Borrelia recurrentis, R. conorii, and R. prowazekii antibodies in the homeless. Our study shows a high prevalence of louse-borne infections in the homeless and a high degree of exposure to tick-borne diseases and scabies. Despite effective treatment for Bartonella quintana bacteremia and the efforts made to delouse this population, Bartonella quintana remains endemic, and we found hallmarks of epidemic typhus and relapsing fever. The uncontrolled louse infestation of this population should alert the community to the possibility of severe re-emerging louse-borne infections.

Bartonella and Coxiella antibodies in 334 prospectively studied episodes of infective endocarditis in Sweden

Bartonella spp. have been identified as aetiological agents in culture-negative infective endocarditis (IE). Coxiella burnetii may cause chronic Q-fever with endocarditis, 334 blood samples collected from 329 patients (334 episodes) with IE diagnosed between 1984 and 1996 in Göteborg, Sweden, were investigated for antibodies to Bartonella spp. and C. burnetii. 71 of the episodes (21%) were blood culture negative. A microimmunofluorescence assay revealed immunoglobulin G (IgG) antibodies to Bartonella in 13 of the culture verified episodes and in 2 of the culture-negative episodes. Three of the patients had IgG antibodies to > or = 200 in the blood culture-verified group, but none had a titre > or = 800, the cut-off level for Bartonella endocarditis. One patient had elevated antibodies to C. burnetii, diagnosing chronic Q-fever endocarditis. In conclusion, serologically verified Bartonella endocarditis is not prevalent in western Sweden and Q-fever endocarditis is rare.

Pericardial effusion in a homeless man due to Bartonella quintana

Bartonella quintana may cause trench fever, endocarditis, bacillary angiomatosis, and chronic bacteremia, and a reemergence among homeless populations in cities has been noted. Pericarditis from Rickettsia conorii and Coxiella burnetii infection has been described, but there have been no reports of pericarditis due to Bartonella spp. We report a case of pericardial effusion due to Bartonella quintana in a homeless man, diagnosed on the basis of PCR detection of Bartonella quintana in a pericardial biopsy sample and a fourfold rise in antibody titers. The patient recovered within 2 weeks with antibiotics active against bartonellae.

Randomized open trial of gentamicin and doxycycline for eradication of Bartonella quintana from blood in patients with chronic bacteremia

Chronic Bartonella quintana bacteremia is known to occur in homeless people exposed to lice. We present here the results of an open randomized trial performed to evaluate the efficacy of doxycycline in combination with gentamicin in the eradication of B. quintana bacteremia. From 1 January 2001 to 1 April 2002, homeless people with blood cultures positive for B. quintana were randomized to receive either no treatment (untreated controls) or a combination of gentamicin (3 mg/kg of body weight/day intravenously for 14 days) and doxycycline (200 mg/day orally for 28 days). Patients were evaluated from the results of blood cultures performed between day 28 (the end of treatment) and day 90 postinclusion. Intention-to-treat analysis of 20 included patients showed eradication of bacteremia in 7 out of 9 treated patients versus 2 out of 11 untreated controls (P = 0.01). In the per-protocol analysis, eradication was obtained for 7 out of 7 treated patients versus 2 out of 9 untreated controls (P = 0.003). This study demonstrates the efficiency of the combination of doxycycline and gentamicin in eradicating B. quintana bacteremia.

Urban zoonoses caused by Bartonella, Coxiella, Ehrlichia, and Rickettsia species

The last half of the 20th Century witnessed an increase in the occurrence and recognition of urban zoonoses caused by members of the genera Bartonella, Coxiella, Ehrlichia, and Rickettsia, all traditionally considered to be members of the family Rickettsiaceae. In recent years, new human pathogens (Bartonella elizabethae, Bartonella henselae, and Rickettsia felis) have been recognized in urban environments. Other newly recognized pathogens (Ehrlichia chaffeensis and Ehrlichia phagocytophila in the United States) have sylvan zoonotic cycles but are present in urban areas because their vertebrate hosts and associated ectoparasitic arthropod vectors are able to survive in cities. Still other agents, which were primarily of historical importance (Bartonella quintana) or have not traditionally been associated with urban environments (Rickettsia rickettsii), have been recognized as causes of human disease in urban areas. Some diseases that have traditionally been associated with urban environments, such as rickettsialpox (caused by Rickettsia akari) and murine typhus (caused by Rickettsia typhi), still occur in large cities at low or undetermined frequencies and often go undetected, despite the availability of effective measures to diagnose and control them. In addition, alternate transmission cycles have been discovered for Coxiella burnetii, Rickettsia prowazekii, and R. typhi that differ substantially from their established, classic cycles, indicating that the epidemiology of these agents is more complex than originally thought and may be changing. Factors leading to an increase in the incidence of illnesses caused by these bacteria in urban areas include societal changes as well as intrinsic components of the natural history of these organisms that favor their survival in cities. Transovarial and transstadial transmission of many of the agents in their arthropod hosts contributes to the highly focal nature of many of the diseases they cause by allowing the pathogens to persist in areas during adverse times when vertebrate amplifying hosts may be scarce or absent. Domesticated animals (primarily cats, dogs, and livestock) or commensal rodents [primarily Norway rats (Rattus norvegicus) and house mice (Mus musculus)] can serve as vertebrate amplifying hosts and bring these agents and their ectoparasitic arthropod vectors into direct association with humans and help maintain transmission cycles in densely populated urban areas. The reasons for the increase in these urban zoonoses are complex. Increasing population density worldwide, shifts in populations from rural areas to cities, increased domestic and international mobility, an increase in homelessness, the decline of inner-city neighborhoods, and an increase in the population of immunosuppressed individuals all contribute to the emergence and recognition of human diseases caused by these groups of agents. Due to the focal nature of infections in urban areas, control or prevention of these diseases is possible. Increased physician awareness and public health surveillance support will be required to detect and treat existing urban infections caused by these agents, to determine the disease burden caused by them, to design and implement control programs to combat and prevent their spread, and to recognize emerging or resurging infections caused by members of these genera as they occur.

Five-member gene family of Bartonella quintana

Bartonella quintana, the agent of trench fever and an etiologic agent of bacillary angiomatosis, has an extraordinarily high hemin requirement for growth compared to other bacterial pathogens. We previously identified the major hemin receptor of the pathogen as a 30-kDa surface protein, termed HbpA. This report describes four additional homologues that share approximately 48% amino acid sequence identity with hbpA. Three of the genes form a paralagous cluster, termed hbpCAB, whereas the other members, hbpD and hbpE, are unlinked. Secondary structure predictions and other evidence suggest that Hbp family members are beta-barrels located in the outer membrane and contain eight transmembrane domains plus four extracellular loops. Homologs from a variety of gram-negative pathogens were identified, including Bartonella henselae Pap31, Brucella Omp31, Agrobacterium tumefaciens Omp25, and neisserial opacity proteins (Opa). Family members expressed in vitro-synthesized proteins ranging from ca. 26.5 to 35.1 kDa, with the exception of HbpB, an approximately 55.9-kDa protein whose respective gene has been disrupted by a approximately 510 GC-rich element containing variable-number tandem repeats. Transcription analysis by quantitative reverse transcriptase-PCR (RT-PCR) indicates that all family members are expressed under normal culture conditions, with hbpD and hbpB transcripts being the most abundant and the rarest, respectively. Mutagenesis of hbpA by allelic exchange produced a strain that exhibited an enhanced hemin-binding phenotype relative to the parental strain, and analysis by quantitative RT-PCR showed elevated transcript levels for the other hbp family members, suggesting that compensatory expression occurs.

Ectoparasitic infestations in homeless children

Most human ectoparasites live on the surface of their host and depend on that host to complete their life cycle. The most common ectoparasitic infestations of medical importance in humans include pediculosis, scabies, myiasis, and tungiasis. Different host factors are related, with increased risk of acquiring ectoparasitic infestation occurring among the homeless. Although these ectoparasitic infections can be found worldwide, their prevalence is affected significantly by environmental conditions in different geographical areas. This review focuses on the epidemiology, clinical presentation, diagnosis, and treatment of common ectoparasitic infestations among homeless children and their families. The most frequent bacterial infections associated with these infestations also are discussed.

Human pathogens in body and head lice

Using polymerase chain reaction and sequencing, we investigated the prevalence of Rickettsia prowazekii, Bartonella quintana, and Borrelia recurrentis in 841 body lice collected from various countries. We detected R. prowazekii in body lice from Burundi in 1997 and in lice from Burundi and Rwanda in 2001; B. quintana infections of body lice were widespread. We did not detect B. recurrentis in any lice.

Bartonella quintana Bacteremia among Homeless People

Bartonella quintana infections have recently reemerged, predominantly among the homeless populations in cities in both Europe and the United States. B. quintana can cause trench fever, endocarditis, and chronic bacteremia; the human body louse is the only known vector. Homeless people who presented to the emergency departments of University Hospital in Marseilles, France, were studied, as were those who had been admitted to other medical facilities in the city since 1 January 1997. Samples of blood and body lice were collected for culture for B. quintana and for serological testing. Bartonella bacteremia was associated with sweats, evidence of louse infestation, serological tests that were positive for B. quintana, and high titers of B. quintana antibody. Bacteremia was also associated with being homeless for <3 years. Asymptomatic, prolonged bacteremia (duration, up to 78 weeks) and intermittent bacteremia were found to occur. Data obtained regarding antibiotic regimens showed that treatment with gentamicin and doxycycline was effective in preventing relapses of bacteremia.

Detection of Bartonella quintana from body lice (Anoplura: Pediculidae) infesting homeless people in Tokyo by molecular technique

We report detection of Bartonella quintana Brenner, the pathogenic agent of trench fever, from body lice, Pediculus humanus L., infesting homeless people in Tokyo by polymerase chain reaction. Two of 12 (16.7%) homeless were infested with Bartonella-positive body lice. From the current status of the recent increase of homeless people in many large cities of the developed countries, a medical examination of homeless people should be carefully performed in the consideration of trench fever. Sampling of body lice from clothing of homeless people is recommended for quick and accurate diagnosis of trench fever through the detection of B. quintana DNA.

Detection and culture of Bartonella quintana, Serratia marcescens, and Acinetobacter spp. from decontaminated human body lice

As part of a survey for trench fever among homeless people in Marseilles, France, we attempted isolation of Bartonella quintana from body lice. A decontamination protocol of immersion in 70% ethanol with 0.2% iodine was devised and was tested with a laboratory colony of body lice. Lice which had been experimentally contaminated with either Escherichia coli, Staphylococcus epidermidis, or Acinetobacter spp. were successfully decontaminated, and this process did not prevent the culture of B. quintana from these lice. One hundred sixty-one lice obtained from homeless patients were studied by the protocol. B. quintana was isolated on axenic medium from 15 of 161 body lice and was detected in 41 of 161 lice by PCR. Acinetobacter spp. and Serratia marcescens were also isolated from body lice. The sensitivities of PCR and culture of B. quintana were 98 and 36%, respectively. These procedures may be useful for epidemiologic studies of trench fever and for the recovery of strains for characterization and comparison.

Hemin-binding surface protein from Bartonella quintana

Bartonella quintana, the agent of trench fever and a cause of endocarditis and bacillary angiomatosis in humans, has the highest reported in vitro hemin requirement for any bacterium. We determined that eight membrane-associated proteins from B. quintana bind hemin and that a approximately 25-kDa protein (HbpA) was the dominant hemin-binding protein. Like many outer membrane proteins, HbpA partitions to the detergent phase of a Triton X-114 extract of the cell and is heat modifiable, displaying an apparent molecular mass shift from approximately 25 to 30 kDa when solubilized at 100 degrees C. Immunoblots of purified outer and inner membranes and immunoelectron microscopy with whole cells show that HbpA is strictly located in the outer membrane and surface exposed, respectively. The N-terminal sequence of mature HbpA was determined and used to clone the HbpA-encoding gene (hbpA) from a lambda genomic library. The hbpA gene is 816 bp in length, encoding a predicted immature protein of approximately 29.3 kDa and a mature protein of 27.1 kDa. A Fur box homolog with 53% identity to the Escherichia coli Fur consensus is located upstream of hbpA and may be involved in regulating expression. BLAST searches indicate that the closest homologs to HbpA include the Bartonella henselae phage-associated membrane protein, Pap31 (58.4% identity), and the OMP31 porin from Brucella melitensis (31.7% identity). High-stringency Southern blots indicate that all five pathogenic Bartonella spp. possess hbpA homologs. Recombinant HbpA can bind hemin in vitro; however, it does not confer a hemin-binding phenotype upon E. coli. Intact B. quintana treated with purified anti-HbpA Fab fragments show a significant (P < 0.004) dose-dependent decrease in hemin binding relative to controls, suggesting that HbpA plays an active role in hemin acquisition and therefore pathogenesis. HbpA is the first potential virulence determinant characterized from B. quintana.

Emerging and resurging vector-borne diseases

Over the last four decades, a number of arthropod-borne infections have been recognized for the first time. Some have become of considerable public health importance, such as dengue hemorrhagic fever (DHF), and others are spreading geographically and their incidence is increasing. There has been an important recrudescence of several long-known vector-borne diseases. Malaria, leishmaniasis, dengue, and plague have resurged in numerous foci, in some cases where they were thought to be under effective control. In most instances, the appearance of new diseases and syndromes and the resurgence of old can be associated with ecological changes that have favored increased vector densities. Dam construction, irrigation and other development projects, urbanization, and deforestation have all resulted in changes in vector population densities that appear to have enabled the emergence of new diseases and the resurgence of old diseases. Greatly increased human travel has spread infectious agents, introducing them into areas in which they had been hitherto absent. It is essential to understand the factors that caused increased vector densities and hence the transmission of disease to prevent the emergence and resurgence of more diseases, as well as to serve as a basis for effective control.