Repository of Research and Investigative Information

Repository of Research and Investigative Information

Kurdistan University of Medical Sciences

Tick-borne relapsing fever in a new highland endemic focus of western Iran

(2009) Tick-borne relapsing fever in a new highland endemic focus of western Iran. Annals of Tropical Medicine and Parasitology.

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Tick-borne relapsing fever (TBRF) is a neglected zoonotic disease caused by infection with spirochaetes of the genus Borrelia. Humans usually contract it from the bite of infected soft ticks of the genus Ornithodoros. In Iran, where the disease is endemic in the mountainous north-western provinces, reports of over 200 cases annually probably under-estimate the true incidence. The species, distribution and infection of ticks that are potential vectors of Borrelia and the clinical and epidemiological characteristics of the local TBRF cases were recently investigated in the villages in and around the county town of Bijar, in north-western Iran. A blood sample from each suspected case of TBRF was checked for B. persica by dark-field microscopy, data were collected on the demographics and clinical manifestations of each confirmed case, and the prevalence of tick infection with borreliae and the monthly incidence of TBRF were evaluated. Between 2000 and 2007, 148 cases of TBRF (each with fever, chills and headache) were passively detected in the town. Most (115) of these were confirmed by microscopy, with the other subjects categorized as probable (21) or suspected cases (12) of TBRF. Most (91) of the 148 subjects were young people, and most came from rural areas and lived in large households in the old mud-and-thatch houses of Bijar. Most (82) of the cases occurred during the summer or early autumn. Overall, 8543 soft ticks (Ornithodoros tholozani, O. lahorensis, Argas persicus and A. reflexus) were collected by clustered random sampling. When a random sample of the O. tholozani ticks (96 of the 577 collected) was checked for B. persica infection, by being crushed and then inoculated intraperitoneally into a mouse or suckling Syrian hamster, 19 were found infected. Peaks in the monthly incidence of TBRF occurred as the numbers of O. tholozani in the tick collections peaked, and it seems likely that most of the cases were caused by B. persica transmitted by O. tholozani. Further studies in Iran, to map the geographical variation in the prevalence of soft-tick infection with Borrelia and identify any Borrelia reservoirs, are recommended. © The Liverpool School of Tropical Medicine 2009.

Item Type: Article
Keywords: adolescent; adult; aged; animal experiment; animal model; Argas; Argas persicus; argas reflexus; article; autumn; blood sampling; Borrelia; Borrelia infection; borrelia persica; child; clinical feature; endemic disease; female; geographical variation (species); groups by age; household; human; incidence; infant; Iran; major clinical study; male; microscopy; mouse; nonhuman; Ornithodoros lahorensis; Ornithodoros tholozani; parasite vector; preschool child; prevalence; rural area; school child; summer; Syrian hamster; tick; tick borne disease, Adolescent; Adult; Animals; Argasidae; Child; Child, Preschool; Cricetinae; Cross-Sectional Studies; Endemic Diseases; Housing; Humans; Infant; Iran; Mice; Prevalence; Relapsing Fever; Seasons; Tick Infestations; Young Adult, Argas persicus; Argasidae; Borrelia; Borrelia persica; Ixodida; Mesocricetus auratus; Ornithodoros; Spirochaetes
Page Range: pp. 529-537
Journal or Publication Title: Annals of Tropical Medicine and Parasitology
Volume: 103
Number: 6
Identification Number: 10.1179/136485909X451852
ISSN: 00034983
Depositing User: مهندس جمال محمودپور

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