Cases Of Tick-borne Relapsing Fever Research Articles

Post exposure prophylaxis of tick-borne relapsing fever

Tick-borne relapsing fever (TBRF) is endemic to Israel. Since 2004, the Israel Defence Forces (IDF) has mandated the prophylaxis of tick-bitten subjects with a five-day doxycycline course. We examined the safety and effectiveness of this policy in preventing TBRF. We analyzed the records from January 2004 to January 2007, and identified all reported events of tick bites or TBRF cases. Data were available on 27 events in which 816 soldiers have undergone physical examination following exposure, and seven TBRF cases were recorded in this group-an attack rate of 0.86% compared with the expected rate of 5.34% from previous army data (relative risk [RR] = 0.16). Of those screened, 128 (15.7%) had tick-bite and were intended for prophylaxis, of which four TBRF cases occurred-3.13% attack rate compared with an expected rate of 38.4% in these bitten individuals without prophylaxis (RR = 0.08, number needed to treat = 3). In all cases in which screening and prophylaxis were provided within 48 h of tick bite, complete prevention of TBRF was achieved. No cases of Jarisch-Herxheimer reaction (JHR) was recorded. Tick-bite screening and prophylactic treatment with doxycycline in endemic areas is a practical, safe, and highly effective policy for preventing TBRF.

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

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.

Tick Talk: Unusually Severe Case of Tick-Borne Relapsing Fever With Acute Respiratory Distress Syndrome—Case Report and Review of the Literature

Borrelia hermsii causes tick-borne relapsing fever (TBRF) in the Pacific Northwest. There are few reports of TBRF-associated acute respiratory distress syndrome. One such unusually severe case is described. Literature is reviewed including diagnosis, treatment, and prevention.

Postexposure Treatment with Doxycycline for the Prevention of Tick-Borne Relapsing Fever

Tick-borne relapsing fever (TBRF) is an acute febrile illness. In Israel, TBRF is caused by Borrelia persica and is transmitted by Ornithodoros tholozani ticks. We examined the safety and efficacy of postexposure treatment to prevent TBRF. In a double-blind, placebo-controlled trial, 93 healthy subjects with suspected tick exposure (52 with signs of tick bites and 41 close contacts--those without signs but with a similar risk of contact with ticks) were randomly assigned to receive either doxycycline (Dexxon, in a dose of 200 mg the first day and then 100 mg per day for four days) or placebo after presumed exposure to TBRF. Cases of TBRF were defined by fever and a positive blood smear. Serologic analysis for cross-reactivity to Borrelia burgdorferi and polymerase chain reaction (PCR) for the borrelia glpQ gene were also performed. After randomization, 47 subjects (26 with signs of tick bites and 21 close contacts) received doxycycline. Forty-six other subjects (26 with signs of tick bites and 20 close contacts) received placebo. All 10 cases of TBRF identified by a positive blood smear were in the placebo group of subjects with signs of a tick bite (P<0.001). These findings suggested a 100 percent efficacy of preemptive treatment (95 percent confidence interval, 46 to 100 percent). PCR for the borrelia glpQ gene was negative at baseline for all subjects and subsequently positive in all subjects with fever and a positive blood smear. Seroconversion was detected in eight of nine cases of TBRF. PCR and serum samples were negative for all of the other subjects tested. No major treatment-associated adverse effects were identified. Treatment with doxycycline is safe and efficacious in preventing TBRF after suspected exposure to ticks in a high-risk environment. (ClinicalTrials.gov number, NCT00237016 [ClinicalTrials.gov].).

The epidemiology of tick-borne relapsing fever in the United States.

Each year, many residents of and visitors to endemic regions of the western United States are exposed to the vector of tick-borne relapsing fever (TBRF), an underrecognized and underreported disease. Through review of report forms and literature review, we identified 450 cases of TBRF acquired in the United States in 11 western states (and in British Columbia by a U.S. resident) from January 1977 to January 2000. Exposure sites were in forested areas, at varying elevations, in mountainous regions (Cascade, Rocky Mountain, San Bernardino, and Sierra Nevada ranges) of the United States and Canada and in limestone caves in central Texas. Only 13 counties accounted for approximately 50% of all cases. Forty percent of the cases were not residents of the state where TBRF exposure occurred, including 7% from 11 states where TBRF is not endemic. TBRF is endemic in the United States and is a disease affecting travelers, who may return home with the disease to areas where physicians are not familiar with it.

Outbreak of tick-borne relapsing fever at the north rim of the Grand Canyon: evidence for effectiveness of preventive measures.

An outbreak of tick-borne relapsing fever (TBRF) originating at the North Rim of Grand Canyon National Park was investigated in 1990. To determine risk factors for the disease, almost 7,000 parties of visitors were surveyed; over half responded, representing > 10,000 people. Fifteen cases of confirmed or probable TBRF were identified in visitors and 2 in employees. All patients except one experienced symptoms after overnight stays in a group of cabins that had not been rodent-proofed after a TBRF outbreak in 1973 (relative risk for visitors [RR] 8.2, 95% confidence interval [CI] 1.1-62). Seven cases of TBRF were associated with a single cabin (RR 98, 95% CI 30-219). Structural flaws and rodent nests were common in the implicated cabins and rare in unaffected cabins. This investigation suggests that measures to rodent-proof cabins at sites where TBRF is endemic prevent reinfestation of cabins by infected rodents and tick vectors, thereby preventing the spread of disease in humans.

Spraying tick-infested houses with lambda-cyhalothrin reduces the incidence of tick-borne relapsing fever in children under five years old

Tick-borne relapsing fever (TBRF) is a major cause of morbidity and mortality of children in central Tanzania. This study assessed the effect of house interior residual spraying with lambda-cyhalothrin on domestic tick infestation and the incidence of TBRF in children under 5 years old. Two neighbouring villages were studied: one was sprayed with insecticide, the other left untreated. Samples of earth from the floors of 50 houses before and after spraying, and 50 houses in the control village, were sieved and ticks counted. The incidence of TBRF was estimated by microscopy of thick blood films taken from all children under 5 years old presenting with fever to the village dispensary or health workers. After 2 cycles of spraying, no tick was found in the treated houses; in the controls, tick numbers remained high. In the treated village there were 29 cases of TBRF among the 960 children under 5 years old in the 4 months before spraying, and one in the 4 months after spraying. In the control village there were 10 and 4 cases in the same periods among the 510 children. There was a significant reduction of 0·09 in the odds ratio of infection after spraying (95% confidence interval 0·01–0·87).

Tick‐Borne Relapsing Fever in the Northwestern United States and Southwestern Canada

Records from 182 cases of tick-borne relapsing fever (TBRF) were reviewed. In confirmed cases, there was febrile illness, and spirochetes were identified on peripheral blood preparations. In probable cases, there were clinical features of TBRF and either the same exposure as a confirmed case or serological (indirect fluorescent antibody test and western blotting [WB]) evidence of infection with Borrelia hermisii. Sera also were tested for antibody to Borrelia burgdorferi. We identified 133 confirmed and 49 probable cases of TBRF. A Jarisch-Herxheimer reaction was reported in 33 (54.1%) of 61 cases for which this information was available. Most patients who had antibodies to B. hermsii were serologically positive for B. burgdorferi, and WB demonstrated false positivity of testing for B. burgdorferi. Thirty-five (21%) of 166 cases were unreported to public health authorities. In 52 cases, there were more than two relapses before the diagnosis. This study demonstrates that TBRF is underrecognized and underreported and may be falsely identified as Lyme disease.

Tick-borne borreliosis in West Africa

Reported cases of tick-borne relapsing fever due to the spirochaete Borrelia crocidurae are rare in West Africa, and few epidemiological data are available. To see how common relapsing fever is in Senegal thick blood smears from cases of fever of unknown origin and from randomly selected clinic outpatients from a rural dispensary were examined for Borrelia. The prevalence of Borrelia infections in small mammals was also assessed. Borrelia was seen in smears of 12 (0·9%) of 1340 children. All children who tested positive had complained of acute fever. Prevalence was 0% (0/496), 0·5% (2/417), 1 ·6% (5/308), and 4·2% (5/119) at ages 0-1, 2-4, 5-9, and 10-14, respectively. 26 other instances of borreliosis were seen in patients from different regions of Senegal. Blood samples from 7 of these patients were inoculated intraperitoneally into white mice; serious infection developed in all mice. Borrelia was seen in thick smears from 65 of 461 wild rodents or insectivores. Six rodents species were infected. From a sample of 93 rodents, 33·3% were infected, as judged by intraperitoneal inoculation of white mice, compared with 14·1% by direct smear examination. The findings suggest that borreliosis has a wide distribution and a high incidence in Senegal. This disease may be a major cause of morbidity in rural areas throughout much of West Africa.

The Spectrum of Relapsing Fever in the Rocky Mountains

Between 1940 and 1976, two cases of tick-borne relapsing fever were reported in Colorado, but since 1977, 23 confirmed cases have occurred. All patients had fever, with a mean of 2.8 febrile episodes (range, one to six). Complications included thrombocytopenia, endophthalmitis, meningitis, abortion, in utero infection, and erythema multiforme. All treated patients were eventually cured with antibiotics, although two pregnant patients failed to be cured by their initial courses of antibiotics. Seven of 21 treated patients had Jarisch-Herxheimer reactions, three of whom required intensive care. Five of nine patients who received tetracycline at an initial dose of 5 mg/kg or more had reactions v none of four patients treated with lower doses. Possible causes of the recent increased incidence include increased physician awareness and reporting, improved diagnostic techniques, and an actual increase due to a larger population at risk. Because summertime visits to the Rocky Mountains are becoming increasingly popular, physicians elsewhere should know how to recognize and treat this condition.

Penicillin Therapy in Relapsing Fever

SummaryA case of tick-borne relapsing fever successfully treated by penicillin is reported. The experimental data concerning penicillin therapy in this disease are briefly reviewed and the possible clinical usefulness of this form of chemotherapy is pointed out.