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Results for “Relapsing Fever”

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PubMed1977

Tick-borne relapsing fever: an interstate outbreak originating at Grand Canyon National Park.

During the 1973 summer season, 27 employees and 35 overnight guests at the North Rim, Grand Canyon National Park, Arizona, acquired febrile illnesses compatibel with relapsing fever. Sixteen cases were confirmed by finding Borrelia spirochetes in peripheral blood smears or inoculated Swiss mice. Retrospective surveys of 278 employees and 7247 guests at the park revealed that acquisition of illness was significantly associated with the persons sleeping in rustic log cabins and acquiring bites of "unknown" insects. From rodent nesting materials found in the walls and attics of cabins where cases had occurred, infective Ornithodoros hermsi ticks were recovered. Exceptional activity of ticks in human populations appeared to have resulted from a decreased population of the ticks' usual rodent hosts. Vector control activities consisted of spraying the cabins with residual insecticide, removing nesting materials, and "rodent proofing." This outbreak, the largest yet identified in North America, extends the known range of a principal vector and establishes the North Rim as an endemic source of tick-borne relapsing fever.

Adult↗

PubMed1989

[Relapsing fever seen in Europe: epidemiology, diagnosis, course and treatment].

In most European countries relapsing fevers, caused by different Borrelia species, are imported diseases. This diagnosis should be considered in a patient with fever recently back from an endemic region, especially if he went through several febrile episodes or if he has jaundice, spleen enlargement, a rash and signs of haemorrhage or meningoencephalitis.

Anti-Bacterial Agents↗

PubMed1992

Identification of the tick-borne relapsing fever spirochete Borrelia hermsii by using a species-specific monoclonal antibody.

Borrelia hermsii causes a relapsing fever in humans and is one of several species of tick-borne spirochetes known to occur in the western United States. Spirochetes observed in the peripheral blood of patients acutely ill have been presumptively identified in the past by the geographic location of exposure and the probable species of tick vector. We describe a monoclonal antibody (H9826) that bound to the flagellar protein of B. hermsii but not to those of any of the other species tested, which included B. parkeri, B. turicatae, B. coriaceae, B. anserina, B. burgdorferi, and Leptospira interrogans serovar ballum. This antibody bound efficiently to B. hermsii in an indirect immunofluorescence assay and was used to rapidly detect and identify this spirochete in the peripheral blood of experimentally infected mice and in the central ganglia of Ornithodoros hermsi ticks. H9826 can rapidly confirm the identification of B. hermsii to increase our understanding concerning the geographic distribution, vector specificity, and epidemiological significance of this zoonotic human pathogen.

Antibodies, Bacterial↗

PubMed1977

Louse-borne relapsing fever: II. Combined penicillin and tetracycline therapy in 160 Sudanese patients.

One hundred and sixty patients with louse-borne relapsing fever were treated with a combination therapy of procaine penicillin and tetracycline. Fortified procaine penicillin B.P. was given as 400,000 units in the first day. This was followed the next day by 2 g tetracycline orally in divided doses for seven days. A mild rise in temperature was observed in 22 (13-7%) patients within four hours of administering penicillin. Rigors and hypotension occurred in one patient. Relapse occurred in two patients, of whom one had concomitant typhoid and one visceral leishmaniasis. The combined therapy has been found to be effective and safe. It lacks the disadvantages of penicillin (relapses) and tetracycline (severe reaction), when each drug is used alone.

Adolescent↗

PubMed1992

Relapsing fever associated with ARDS in a parturient woman. A case report and review of the literature.

We report a patient who survived acute respiratory failure associated with tick-borne relapsing fever in the third trimester of pregnancy. The fetus was delivered by cesarian section and did not have spirochetemia. The severity of the patient's illness may be related to the immunosuppressive effects of pregnancy.

Adult↗

PubMedDate not supplied

Tick-borne relapsing fever in central Tanzania.

Between October 1985 and September 1986, 488 children aged less than 15 years, 45 pregnant women, 21 other women and 18 men with tick-borne relapsing fever (TBRF) were seen at Mvumi Hospital, Central Tanzania. 88% of the children were less than 5 years old and 36% were less than 1 year. Twelve children were less than 1 month old and some of the 10 infants diagnosed at between 4 and 12 days of age were cases of congenital infection. The clinical features of TBRF in the children and pregnant women were compared with 129 children with a similar age distribution and 52 pregnant women, respectively, who had blood smears positive for malaria but negative for spirochaetes. The common presenting features in children with TBRF were a high fever, splenomegaly, convulsions, and meningism. The difficulty of differentiation from malaria is described. Severe disease in both children and adults was associated with high density of spirochaetes in blood smears. Of the 45 infected pregnant women, 22 (49%) went into labour. One of the deliveries was an abortion and 10 were preterm infants, 4 of whom died. There were no maternal deaths. The estimated overall mortality for children was 1.6%, and 2.3% for those aged less than 1 years; for the 95 children admitted it was 8.4%. Penicillin was a satisfactory treatment for all ages, with a relapse rate of 4.7%. Recommendations for patient management are given.

Adolescent↗

PubMed1991

Variable antigen genes of the relapsing fever agent Borrelia hermsii are activated by promoter addition.

Borrelia hermsii, an agent of relapsing fever, avoids the host's immune response by means of multiphasic antigenic variation. Serotype specificity is determined by variable antigens called the Vmp lipoproteins. Through recombination between linear plasmids a formerly silent vmp gene replaces another vmp gene at a telomeric expression locus. We examined strain HS1 borreliae before and after a switch from serotype 7 to serotype 21. The nucleotide sequences of 5' regions of silent and expressed vmp7 and vmp21 were determined. Silent and active vmp7 and vmp21 genes shared a block of homologous sequences surrounding their 5' ends. Sequences upstream of silent vmp7 and vmp21 genes lacked the promoter and substantially differed from each other. In this antigenic switch a vmp gene was activated by a recombination that placed it downstream of a promoter.

Antigenic Variation↗

PubMed1990

The variable antigens Vmp7 and Vmp21 of the relapsing fever bacterium Borrelia hermsii are structurally analogous to the VSG proteins of the African trypanosome.

The relapsing fever agent Borrelia hermsii avoids the host's immune response by the strategy of multiphasic antigenic variation. A given Borrelia cell can express one of a number of alleles for polymorphic outer-membrane proteins, known as Vmp proteins. The genes for the variant-specific Vmp proteins of serotypes 7 and 21 of B. hermsii strain HS1 were sequenced. The genes, which were designated vmp7 and vmp21, were obtained from populations of borreliae before and after a switch in serotypes from 7 to 21. The analysis showed that vmp7 and vmp21 are 77% identical in terms of their coding sequence. The deduced translation products of vmp7 and vmp21 are polypeptides of 369 (37.2 kD) and 364 amino acids (37.1 kD), respectively. Vmp7 and Vmp21 have sequence features of prokaryotic lipoproteins and are processed as such during expression in E. coli. The secondary structure predictions of the Vmp proteins reveals analogous structures to the VSG proteins of the African trypanosome.

Amino Acid Sequence↗

PubMed1992

The relapsing fever agent Borrelia hermsii has multiple copies of its chromosome and linear plasmids.

Borrelia hermsii, a spirochete which causes relapsing fever in humans and other mammals, eludes the immune response by antigenic variation of the "Vmp" proteins. This occurs by replacement of an expressed vmp gene with a copy of a silent vmp gene. Silent and expressed vmp genes are located on separate linear plasmids. To further characterize vmp recombination, copy numbers were determined for two linear plasmids and for the 1-megabase chromosome by comparing hybridization of probes to native DNA with hybridization to recombinant plasmids containing borrelial DNA. Plasmid copy numbers were also estimated by ethidium bromide fluorescence. Total cellular DNA content was determined by spectrophotometry. For borrelias grown in mice, copy numbers and 95% confidence intervals were 14 (12-17) for an expression plasmid, 8 (7-9) for a silent plasmid, and 16 (13-18) for the chromosome. Borrelias grown in broth medium had one-fourth to one-half this number of plasmids and chromosomes. Staining of cells with 4',6-diamidino-2-phenylindole revealed DNA to be distributed throughout most of the spirochete's length. These findings indicate that borrelias organize their total cellular DNA into several complete genomes and that cells undergoing serotype switches do one or more of the following: (1) coexpress Vmps from switched and unswitched expression plasmids for at least three to five generations, (2) suppress transcription from some expression plasmid copies, or (3) partition expression plasmids nonrandomly. The lower copy number of the silent plasmid indicates that nonreciprocal Vmp gene recombination may result from loss of recombinant silent plasmids by segregation.

Bacterial Outer Membrane Proteins↗

PubMed1992

Polymerase chain reaction primers and probes derived from flagellin gene sequences for specific detection of the agents of Lyme disease and North American relapsing fever.

By cloning and sequencing the flagellin gene of Borrelia hermsii and comparing this sequence with that of the corresponding gene from B. burgdorferi, I identified a central region within the two genes which showed a reduced level of sequence similarity. Oligonucleotide sequences selected from this region produced species-specific amplimers when used in polymerase chain reaction experiments. Thus, primers derived from the B. burgdorferi sequence amplified a 276-bp fragment from 22 strains of B. burgdorferi of diverse geographic origin but not from 5 strains of B. hermsii, 5 other Borrelia species, 16 Treponema, Leptospira, and Spirochaeta species, or representatives of 10 other bacterial genera. However, when the amplified fragments were tested for hybridization with an oligonucleotide probe derived from the nonhomologous region, seven strains from either Germany or Switzerland did not hybridize. Cloning and sequencing of the amplified fragments from these strains revealed that the 22 strains of B. burgdorferi tested could be divided into three groups based on the nucleic acid sequence of the central region of the flagellin gene. With this information, oligonucleotide probes that hybridized to the amplified fragments and were able to differentiate the three groups of B. burgdorferi were designed. The corresponding primers, derived from the B. hermsii gene sequence, were tested for their ability to amplify DNA from this collection of strains. Although no amplification was obtained with representatives of the three groups of B. burgdorferi or various Treponema, Leptospira, and Spirochaeta species, amplification was obtained with the five other Borrelia species (B. parkeri, B. turicatae, B. crocidurae, B. anserina, and B. coriaceae) in addition to the five strains of B. hermsii. Sequencing of the amplified fragments from one strain of B. hermsii as well as B. parkeri and B. turicatae allowed the design of oligonucleotide probes that were able to differentiate the three species of North American relapsing fever spirochetes into two separate groups. These studies suggest that there is sufficient diversity within the flagellin gene sequences of closely related Borrelia species to differentiate them into groups and to pursue taxonomic studies both within and between species.

Amino Acid Sequence↗

PubMed1991