Search

SUMMARYBats (order Chiroptera, suborders Megachiroptera [“flying foxes”] and Microchiroptera) are abundant, diverse, and geographically widespread. These mammals provide us with resources, but their importance is minimized and many of their populations and species are at risk, even threatened or endangered. Some of their characteristics (food choices, colonial or solitary nature, population structure, ability to fly, seasonal migration and daily movement patterns, torpor and hibernation, life span, roosting behaviors, ability to echolocate, virus susceptibility) make them exquisitely suitable hosts of viruses and other disease agents. Bats of certain species are well recognized as being capable of transmitting rabies virus, but recent observations of outbreaks and epidemics of newly recognized human and livestock diseases caused by viruses transmitted by various megachiropteran and microchiropteran bats have drawn attention anew to these remarkable mammals. This paper summarizes information regarding chiropteran characteristics and information regarding 66 viruses that have been isolated from bats. From these summaries, it is clear that we do not know enough about bat biology; we are doing too little in terms of bat conservation; and there remain a multitude of questions regarding the role of bats in disease emergence.

Serum samples from people exposed to sheep at a research facility were evaluated by a commercial laboratory and resulted in an overall Coxiella burnetii seroprevalence of 75%. We interviewed individuals to determine exposure history and compatible illness, and retested their sera. Analysis indicated that the commercial laboratory was misinterpreting its results; when corrected, the seroprevalence dropped to 27%. Test kits of the brand used by the commercial laboratory gave equivalent results to the in-house CDC assay when tested in parallel at CDC. Upon final analysis, only the attending veterinarian was confirmed as a Q fever case. This event resulted in increased risk reduction protocols at the research facility and improved public health communication among health authorities. This pseudoepidemic resulted from a lapse in laboratory quality control for testing. Similar errors can be avoided through standardization and improved review of laboratory procedures.Vector-Borne Zoonotic Dis. 4, 343–350.

This report describes the data accumulated during the first 5 years of national surveillance for the human ehrlichioses in the United States and territories, from its initiation in 1997 through 2001. Reported cases of human monocytic and granulocytic ehrlichiosis (HME and HGE) and cases of 'other ehrlichiosis' (OE), where the agent was unspecified, originated from 30 states. As anticipated, most HME cases were from the south-central and southeastern United States, while HGE was most commonly reported from the northeastern and upper-Midwestern region. State-level incident reports of 487 HME, 1,091 HGE, and 11 OE cases were evaluated. The average annual incidences of HME, HGE, and OE per million persons residing in states reporting disease were 0.7, 1.6, and 0.2, respectively. The median ages of HME (53 yr) and HGE cases (51 yr) were consistent with published patient series. Most (> 57) ehrlichiosis patients were male. The results suggest that national surveillance for the ehrlichioses, although imperfect in coverage, will help define endemic regions and may be useful for monitoring long-term trends. Although the data appear representative of the demographic profiles established for HME and HGE, rigorous evaluation of the system is required. Methods are proposed for evaluating the quality and representativeness of HME and HGE surveillance data, using well-established surveillance systems for Rocky Mountain spotted fever and Lyme disease.

Rickettsialpox, a spotted fever rickettsiosis, was first identified in New York City (NYC) in 1946. During the next five years, approximately 540 additional cases were identified in NYC. However, during the subsequent five decades, rickettsialpox received relatively little attention from clinicians and public health professionals, and reporting of the disease diminished markedly. During February 2001 through August 2002, 34 cases of rickettsialpox in NYC were confirmed at CDC from cutaneous biopsy specimens tested by using immunohistochemical (IHC) staining, PCR analysis, and isolation of Rickettsia akariin cell culture, as well as an indirect immunofluorescence assay of serum specimens. Samples were collected from patients with febrile illnesses accompanied by an eschar, a papulovesicular rash, or both. Patients originated predominantly from two boroughs (Manhattan and the Bronx). Only 8 (24) of the cases were identified prior to the reports of bioterrorism-associated anthrax in the United States during October 2001, and lesions of several patients evaluated during and subsequent to this episode were suspected initially to be cutaneous anthrax. IHC staining of biopsy specimens of eschars and papular lesions were positive for spotted fever group rickettsiae for 32 patients. Of the eleven patients for whom paired serum samples were obtained, all demonstrated fourfold or greater increases in antibody titers reactive with R. akari. The 17-kDa protein gene sequence of R. akariwas amplified from eschars of five patients. Four isolates of R. akariwere obtained from cutaneous lesions. Possible factors responsible for the increase in clinical samples evaluated for rickettsialpox during this interval include renewed clinical interest in the disease, improved diagnostic methods, epizootiological influences, and factors associated with the recent specter of bioterrorism.

SUMMARYEhrlichia chaffeensis is an obligately intracellular, tick-transmitted bacterium that is maintained in nature in a cycle involving at least one and perhaps several vertebrate reservoir hosts. The moderate to severe disease caused by E. chaffeensis in humans, first identified in 1986 and reported for more than 1,000 patients through 2000, represents a prototypical “emerging infection.” Knowledge of the biology and natural history of E. chaffeensis, and of the epidemiology, clinical features, and laboratory diagnosis of the zoonotic disease it causes (commonly referred to as human monocytic ehrlichiosis [HME]) has expanded considerably in the period since its discovery. In this review, we summarize briefly the current understanding of the microbiology, pathogenesis, and clinical manifestations associated with this pathogen but focus primarily on discussing various ecological factors responsible for the recent recognition of this important and potentially life-threatening tick-borne disease. Perhaps the most pivotal element in the emergence of HME has been the staggering increases in white-tailed deer populations in the eastern United States during the 20th century. This animal serves as a keystone host for all life stages of the principal tick vector (Amblyomma americanum) and is perhaps the most important vertebrate reservoir host for E. chaffeensis. The contributions of other components, including expansion of susceptible human populations, growth and broadening geographical distributions of other potential reservoir species and A. americanum, and improvements in confirmatory diagnostic methods, are also explored.

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 Rickettsia8, 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.

Between 1981 and 1998, 37 cases of rabies were diagnosed in human beings in the United States. Information directly linking the cause of infection to animal bite was available for only eight of these cases. Indirect incrimination of the vector by analysis of cDNA sequences obtained by reverse transcriptase polymerase chain reaction of samples indicated that for all cases (1212) believed to have been acquired in foreign countries, variants of the rabies virus (VRVs) associated with dogs (712 involved known bite histories) were the cause of the rabies infections. In contrast, VRVs associated with bats (bat-associated VRVs or BAVs) were implicated as the cause of 88 (2225) of infections believed to have been acquired within the United States (122 involved known bite histories). Sequence analyses revealed that a single BAV (LnPs), associated with rabid silver-haired (Lasionycteris noctivagans) and Eastern pipistrelle (Pipistrellus subflavus) bats, was implicated in 73 (1622) of bat-associated infections. Silver-haired bats are predominantly solitary and migratory. Eastern pipistrelle bats may occur individually or in small clusters. Both species are only infrequently submitted for rabies testing. Unrecognized bites and unique properties of the LnPs BAV may explain its association with the majority of rabies infections in human beings in the United States.

ABSTRACTA clone expressing an immunoreactive protein with an apparent molecular mass of 44 kDa was selected from an Ehrlichia chaffeensisArkansas genomic library by probing with anti-E. chaffeensishyperimmune mouse ascitic fluid. Nucleotide sequencing revealed an open reading frame (ORF) capable of encoding a 198-amino-acid polypeptide. The ORF contained four imperfect, direct, tandem 90-bp repeats. The nucleotide and deduced amino acid sequences did not show close homologies to entries in the molecular databases. PCR with primers whose sequences matched the sequences flanking the ORF was performed with DNA samples extracted from cell cultures infected with nine different isolates of E. chaffeensis, blood samples from seven patients with monocytic ehrlichiosis, and Amblyomma americanumticks collected in four different states. The resulting amplicons varied in length, containing three to six repeat units. This gene, designated the variable-length PCR target, is useful for PCR detection of E. chaffeensisand differentiation of isolates.

Recounts the author's studies of urban, free-ranging cats and their relationships with the brown, or Norway, rat, two species usually cast in a predator-prey struggle. Previous studies by British ecologist Charles Elton; The author's research in the alleys of Baltimore, Md.; Findings; Implications; Conclusions.

Between August 12 and September 27, 1994, five children in South Florida were hospitalized at a single hospital because of encephalopathy, presenting as status epilepticus, associated with cat-scratch disease (CSD). Diagnoses were confirmed by using an indirect fluorescent antibody test to detect antibody to Bartonella henselae, the causative agent of CSD. These cases represent the first cluster of CSD encephalopathy cases to be recognized in the United States. The patients lived within 7 miles of each other and all reported contact with pet or stray cats before developing regional lymphadenopathy and encephalopathy. All recovered fully. A high proportion of 124 cats from the local area were seropositive (62) or bacteremic (22). This study suggests that B. henselae can be associated with geographically focal clusters of CSD encephalitis and should be considered in the evaluation of children with acute encephalopathy.

In vitro, the opposite sexes ofS. mansoni are attracted to each other by some means of premating communication which culminates in aggregation and copulation of sexual pairs within 24 hr. The system used for time-lapse video tape documentation of worm sexual behavior in vitro is described and evidence of sexual chemoattraction is presented.

Chemical orientation of adult maleSchistosoma mansoni was studied during cultivation in vitro. Directional preference was assessed in culture vessels marked with compass coordinates by the application of circular statistics for determining clustering and orientation to a predicted direction. Organic solvent extracts of fresh female schistosomes and supernatant fluids from 72-hr cultures of female parasites were tested for potential chemotactic activity. Analysis showed significant (P < 0.05) directional preference and clustering of male worms towards test compounds at all time periods (24, 48, and 72 hr) with one mixture of female extracts and at one of three time periods with a second female extract. Male worms did not respond to ecdysone, cholesterol, or solvent controls by orienting in predicted direction, although clustering was observed on two of 12 occasions. These results indicate the presence of a chemoattractant compound(s) in female extracts.

We investigated the suitability of an in vitro culture system for measurement of mating behavior ofSchistosoma mansoni. The criteria used to evaluate this system were the level of phosphorylated nucleotides, egg production, and mating status of parasites. The level of ATP, ADP, AMP, and G6-P was measured at different time intervals during cultivation of worm pairs and remained essentially the same as that of control worms for up to 6 days. Egg production was observed in this system during 19 days of cultivation. Peak egg production occurred on day 4 with 72% of the total eggs being laid during the first week of cultivation. The variability in the number of eggs produced by different pairs ofS. mansoni necessitated the selection and matching of tubes with the same number of eggs after 48 hr. This permitted the detection of small changes in egg production by decreasing intertube variation. Mating recognition between male and femaleS. mansoni was evaluated by culturing separated adult worms with their original partner or with a different partner. During the first 24 hr, mating occurred among a greater percentage of worm pairs comprised of their original partner than among worm pairs comprised of different partners (P < 0.001). After 48 and 72 hr of cultivation, these differences were not statistically significant. Similar results were obtained with a culture of mixed males and females. Two drugs were studied for their effects on the mating ofS. mansoni in vitro. Aminoglutethimide (AG) at a concentration of 1 × 10-4 had no effect on the frequency of mating whereas diethyldithiocarbamate (DDC) completely inhibited mating at a concentration of 3 × 10-6 M and reduced the level of ATP in these worms.

FemaleSchistosoma mansoni and their excretory-secretory (ES) products were extracted with a series of solvents to provide fractions of varying polarity. These fractions were assayed for chemoattractivity to males in vitro. One major component of these mixtures was found to be nonattractive and was identified as cholesterol.n-Pentane- and ether-soluble fractions derived from ES products exhibited chemoattractive activity comparable to that possessed by whole-worm extracts, but appeared to be simpler mixtures.

ABSTRACTRodent (Muridae: Sigmodontinae) blood and sera collected from 14 states were tested for seroreactivity to a cultured isolate of the human granulocytic ehrlichiosis (HGE) agent by using an indirect immunofluorescence assay. Of the 1,240 samples tested, 136 (11%) were found to be reactive at titers of =32. Rodents with HGE agent-specific antibodies were found in New York (23% of 491 samples; geometric mean endpoint titer [GMT] = 441), Connecticut (11% of 100 samples; GMT = 481), California (9% of 32 samples; GMT = 323), Colorado (2% of 212 samples; GMT = 256), Florida (7% of 27 samples; GMT = 362), Maryland (7% of 15 samples; titer = 64), New Jersey (4% of 76 samples; titer = 256), and Wisconsin (13% of 8 samples; titer = 128). Samples from Georgia (n= 16), Illinois (n= 27), Nevada (n= 27), North Carolina (n= 52), Ohio (n= 57), and Utah (n= 100) were not reactive. The earliest seroreactive sample was from aPeromyscus leucopusmouse collected in June 1986 in Connecticut, and the majority of the seroreactive samples (68%) were from this species. Samples from other Peromyscusspecies (P. boylii, P. maniculatus, and P. gossypinus) were also found to be reactive, with a GMT for the genus of 410. Several species of Neotomawoodrats (N. fuscipes, N. lepida, N. albigula, and N. mexicana) from California and Colorado had antibodies that reacted with the HGE agent (genus GMT = 194), suggesting that enzootic cycles of Ehrlichiaspp. exist outside of the areas of confirmed human disease. Attempts to amplify and detect ehrlichial DNA from the limited tissues available (n= 40 animals) were unsuccessful. Further studies are needed to determine the identity of the organisms inducing antibody production in these rodent species and to elucidate the epidemiology and public health importance of these agents.