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PubMed1987

The effect of tick-borne fever on metabolism and renal clearance of sulfadimidine in goats.

The tick-borne fever (TBF) model was used to study the effect of fever on the metabolism of sulfadimidine in goats. During TBF the elimination half-lives were prolonged, and the renal clearance values of sulfadimidine and the majority of its metabolites were markedly diminished compared with those in the uninfected state. During TBF the steady-state levels of the hydroxy metabolites were markedly increased. TBF reduced the extent of hydroxymethylation of the pyrimidine side chain; TBF did not affect acetylation of sulfadimidine. In one goat a progressive accumulation of the metabolites was noticed.

Animals↗
PubMed1991

Purification of Cytoecetes phagocytophila, the causative agent of tick-borne fever, from infected ovine blood.

Cytoecetes phagocytophila, the causative agent of tick-borne fever, was successfully separated by Percoll and Renografin density gradient centrifugation and by cellular affinity chromatography, from the peripheral blood leucocytes of experimentally infected sheep. After centrifugation on Renografin or Percoll density gradients, infectious particles of C. phagocytophila banded at buoyant densities which ranged between 1.063 to 1.140. Rickettsiae separated by wheat germ lectin cellular affinity chromatography retained their morphology but often lost their infectivity. Cell-free C. phagocytophila remained infective to susceptible sheep for 6 months when kept at -114 degrees C in sucrose phosphate buffer with 10 per cent dimethylsulphoxide as a cryopreservative.

Animals↗
PubMedDate not supplied

African tick-bite fever: four cases among Swiss travelers returning from South Africa.

BACKGROUND: African tick-bite fever (ATBF) is a recently described disease belonging to the spotted fever group. It is caused by Rickettsia africae, and cases are mainly diagnosed in travelers returning from sub-Saharan Africa. METHODS: We report four cases of ATBF among Swiss travelers returning from a 1-month trip in rural South Africa. Diagnosis was made on the basis of clinical, epidemiologic and serologic findings that we describe in detail. Serology was performed using microimmunofluorescence (MIF) assay 2 weeks, 6 weeks and 14 months after the commencement of symptoms. RESULTS: All patients developed the typical eschar and a rash; two had a local lymphadenopathy and one a lymphangitic reaction. Two patients developed transient neuropsychiatric symptoms such as headache, irritability and depressed mood. All four patients had rises in both IgM and IgG classes of anti-R. africae antibodies. After 1 year, only two patients still had measurable circulating antibodies. Cross-reactions with R. conorii were noted. Three patients were cured after a short course of doxycycline; one required 15 days of treatment. CONCLUSIONS: ATBF is a benign disease increasingly being diagnosed in travelers. After ruling out malaria, ATBF diagnosis relies upon a detailed travel history and the classical findings of influenza-like symptoms, fever, one or more necrotic eschars, and rash. Serologic tests usually help to confirm the diagnosis. Neuropsychiatric symptoms specifically associated with ATBF are reported here for the first time.

Adolescent↗
PubMed2004

[Rickettsia africae, the agent of African tick-bite fever: an emerging pathogen in the West Indies and Reunion Island (Indian Ocean)].

Rickettsia africae is the agent of African tick bite fever, an emerging disease transmitted by Amblyomma ticks in sub-Saharan Africa. In 1998, we reported the first documented case of R. africae in the New World, in a patient who had returned from Guadeloupe. In order to confirm the presence of R. africae in the West Indies, entomologic surveys were conducted from 1999 to 2003 to collect Amblyomma, which are considered as potential vectors and reservoirs of the bacteria. Ticks were used as epidemiological tools to detect R. africae by molecular tools and/or cultivate the bacteria in shell-vial cell culture. This paper summarizes the results obtained in the West Indies. R. africae was detected and isolated for the first time in Guadeloupe, and then detected by molecular tools in Martinique and St-Kitts and Nevis. These last results confirm our first hypotheses--that is R. africae is prevalent on all the Caribbean islands where A. variegatum ticks have been introduced from Africa in the 18th and 19th centuries. We also present the results of a study conducted on the Reunion Island, a French island in the Indian Ocean. For the first time there, R. africae was detected in A. variegatum ticks, which were probably introduced from the African mainland or Madagascar with the human colonization during the 17th century Thus, clinicians should be aware that patient presenting in the West Indies or on Reunion Island (or after a trip over there) with fever, eschar (often multiple), regional lymphadenopathy and a rash, might be infected by R. africae.

Animals↗
PubMed1996

Rickettsia africae sp. nov., the etiological agent of African tick bite fever.

We propose the name Rickettsia africae sp. nov. (with type strain Z9-Hu) for a distinct species of spotted fever group (SFG) rickettsiae that is the etiological agent of African tick bite fever in humans. This rickettsia has a distinct natural cycle and can be phenotypically distinguished from the other SFG rickettsiae by microimmunofluorescence serotyping, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and by Western blotting (immunoblotting). Genotypic differences between R. africae and the other SFG rickettsiae can be demonstrated by PCR restriction fragment length polymorphism analysis, pulsed-field gel electrophoresis, and sequencing of the 16S rRNA gene.

Africa↗
PubMed2000

[Tick-borne fever (Ehrlichia phagocytophila infection) on a dairy farm in Friesland].

Disease outbreaks, associated with ixodid ticks, among cows on a dairy farm in Friesland, in the north of the Netherlands, were monitored during the summers of 1996, 1997, and 1998. The most important symptoms were a sudden drop in milk yield, fever, apathy, and problems with locomotion. The diagnosis 'tick-borne fever' was confirmed by finding Ehrlichia phagocytophila inclusion bodies in neutrophils of blood smears from sick animals. Significant economic losses due to the disease were recorded each year. Borrelia burgdorferi, although transmitted by the same tick, did not seem to be involved. Further research on tick-borne fever is of particular relevance in connection with recent E. phagocytophila cases diagnosed in dogs and in a human patient in the Netherlands.

Animals↗
PubMed1997

African Tick-Bite Fever: A Case Report.

Mediterranean spotted fever, a disease caused by Rickettsia conorii, is a well-described syndrome among travelers returning from Africa.1 In the present issue of Journal of Travel Medicine2 a case of Rickettsia conorii disease is presented and discussed in context with recently described African tick-bite fever caused by Rickettsia africae. We report the clinical presentation and successful treatment of a traveler who likely had African tick-bite fever.

Journal Article↗
PubMed1990

Efficacy of long-acting oxytetracycline for the prevention of tick-borne fever in calves.

Twenty-six calves which had not previously grazed tick-infested pasture were divided into two equal groups. On May 26, 1988 (day 0) they were turned out into a field of rough grazing where cases of redwater fever had occurred the previous spring. Seven, 14, 21 and 28 days after the start of the trial the animals in one group each received an intramuscular injection of 20 mg/kg bodyweight of long-acting oxytetracycline. During the 60 days of the trial the animals received a severe tick-borne fever challenge, in some cases combined with a redwater fever challenge. An unforeseen complicating factor was the presence of animals persistently infected with bovine viral diarrhoea virus, present in almost equal numbers in both groups. At the end of the trial the treated group weighed on average 16 kg more than the control group, a difference which was attributed to the suppression of tick-borne fever by oxytetracycline.

Animals↗
PubMed2003

African tick bite fever in travelers to rural sub-Equatorial Africa.

To estimate the incidence of, identify risk factors for, and describe the clinical presentation of travel-associated African tick bite fever (ATBF), a rapidly emerging disease in travel medicine, we prospectively studied a cohort of 940 travelers to rural sub-Equatorial Africa. Diagnosis was based on suicide polymerase chain reaction and the detection of specific antibodies to Rickettia africae in serum samples by multiple-antigen microimmunofluorescence assay, Western blotting, and cross-adsorption assays. Thirty-eight travelers, 4.0% of the cohort and 26.6% of those reporting flulike symptoms, had ATBF diagnosed. More than 80% of the patients had fever, headache, and/or myalgia, whereas specific clinical features such as inoculation eschars, lymphadenitis, cutaneous rash, and aphthous stomatitis were seen in < or = 50% of patients. Game hunting, travel to southern Africa, and travel during November through April were found to be independent risk factors. Our study suggests that ATBF is not uncommon in travelers to rural sub-Saharan Africa and that many cases have a nonspecific presentation.

Africa↗
PubMed1975

Rocky Mountain spotted fever (tick-borne typhus) in South Carolina: an educational program and tick/rickettsial survey in 1973 and 1974.

Because the incidence of spotted fever is increasing in South Carolina, campaigns were carried out in 1973 and 1974 to provide the public and medical practitioners, through pamphlets and news media, with information about spotted fever and the ticks which transmit the causative agent, Rickettsia rickettsii. People were also invited to save and submit live ticks removed from vegetation, animals and humans, for examination by the hemolymph test. A total of 1,186 ticks consisting of 987 Dermacentor variabilis, 103 Rhipicephalus sanguineus, and 96 Amblyomma americanum were examined. Rickettsiae identified by direct immunofluorescence as members of the spotted fever group were detected in 49 (4.9%) of the D. variabilis, and 16 (16.6%) of the A. americanum ticks. Two hundred and twenty (199 D. variabilis, 17 A. americanum, and 4 R. sanguineus) were recorded as having been attached to 199 persons. Nine of these ticks (8 D. variabilis, and 1 A. americanum) were hemolymph test-positive for spotted fever-group rickettsiae. Infected ticks originated from each of the three major South Carolina biogeographic regions, namely Piedmont, Sandhill, and Coastal Plain. Since education is the first and most important step in preventing spotted fever, educational programs and tick examination services similar to those decribed, are suggested for other states with high spotted fever incidence.

Animals↗
PubMed1986

Effect of tick-borne fever on the disposition of sulphadimidine and its metabolites in plasma of goats.

The effect of tick-borne fever (TBF) on the plasma disposition of sulphadimidine (SDM) and its metabolites in goats was studied. In uninfected goats, SDM was extensively metabolised mainly by hydroxylation, glucuronidation and to a minor extent by acetylation. In TBF infected goats the hydroxylation of SDM into 6-methylhydroxysulphadimidine (SCH2OH) as well as into 5-hydroxysulphadimidine (SOH) was markedly reduced (-57.6 and -63.6 per cent, respectively). An unidentified metabolite (metabolite X) was detected, which was largely glucuronidated in the uninfected goats. In the TBF infected goats the glucuronide derivatives of the X metabolite and of SOH were barely detectable. In TBF infected goats the plasma concentration of the N4-acetylated metabolite (N4-SDM) was decreased to a lesser extent (-22.1 per cent) than the hydroxy metabolites. Due to the diminished metabolism the elimination half-life of SDM was increased 1.8 times and the total sulphonamide body clearance was diminished compared with findings in the control experiments.

Animals↗