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PubMed2002

Rickettsial infection in farmed Atlantic salmon in eastern Canada.

The cause of death in a postsmolt, Atlantic salmon population with elevated levels of mortalities was investigated. Diagnosis of a rickettsia-like organism was based on gross pathology, histopathology, differential staining, electron microscopy and fluorescent antibody tests. The course of the infection and response to treatment are discussed. This is the first reported occurrence of salmon rickettsias in the Atlantic coast of North or South America.

Animals↗
PubMed1992

Epidemiology of Tsutsugamushi disease in relation to the serotypes of Rickettsia tsutsugamushi isolated from patients, field mice, and unfed chiggers on the eastern slope of Mount Fuji, Shizuoka Prefecture, Japan.

A total of 59 strains of Rickettsia tsutsugamushi were isolated from patients (24 isolates), Apodemus speciosus mice (30 isolates), and unfed larvae of Leptotrombidium scutellare (2 isolates) and Leptotrombidium pallidum (3 isolates) in the Gotenba-Oyama District, Shizuoka Prefecture, Japan. All these isolates were classified into the three serotypes Karp, Kawasaki, and Kuroki based on reactivity with strain-specific monoclonal antibodies. Kawasaki- and Karp-type rickettsiae were isolated from L. scutellare and L. pallidum, respectively, and the geographic distribution of patients and rodents infected with these two types of rickettsiae coincided with the areas densely populated by the respective chiggers. From these results, we conclude that Kawasaki-type rickettsiae are transmitted by L. scutellare and Karp-type ones are transmitted by L. pallidum. Kawasaki-type rickettsial infections were prevalent in early autumn, and Karp-type infections showed a peak of occurrence in the late autumn, reflecting the seasonal fluctuations of L. scutellare and L. pallidum. Isolates of Kuroki-type rickettsiae were obtained only from four patients in October and November, and the relationship between this type of rickettsia and its vector species could not be fully defined.

Animals↗
PubMed1980

In vitro stimulation of human peripheral blood lymphocytes by soluble and membrane fractions of renografin-purified typhus group rickettsiae.

Cell-free extracts of disrupted Renografin-purified Rickettsia typhi and R. prowazekii were evaluated as antigens in lymphocyte transformation assays for cell-mediated immunity to typhus group rickettsiae in 19 individuals with and 9 without histories of exposure to these organisms. Exposure consisted of clinical disease, vaccination with epidemic typhus vaccine, or occupational exposure to these agents. Both the soluble and membrane fractions of disrupted purified rickettsiae were used, and transformation of peripheral blood lymphocytes (PBL) was determined in microcultures by incorporation of [(3)]thymidine. Of the antigen concentrations tested (1 to 400 mug/ml), 10mug/ml appeared to be the most satisfactory. At this concentration, PBL transformation was highly reproducible and correlated well with donor exposure and the presence of enzyme-linked immunosorbent assay anti-typhus group immunoglobulin G. At higher concentrations, PBL from both exposed and control donors often responded to a lipopolysaccharide-like component present in these preparations. Specific transformation responses to rickettsial fractions were detected in several individuals decades after infection or vaccination, indicating that both fractions contained antigens associated with persisting cell-mediated immunity in humans. Generally, stimulation indexes with the soluble fraction were slightly greater than those obtained with corresponding concentrations of the membrane preparation, and in three individuals transformation was observed only with the soluble fraction. PBL transformation to soluble fractions also appeared to have some species specificity, since PBL from individuals with documented R. typhi infections were more responsive to the homologous soluble preparation than to the soluble fraction of R. prowazekii. PBL transformation also correlated well with homologous but only poorly with heterologous enzyme-linked immunosorbent assay immunoglobulin G titers.

Antibodies, Bacterial↗
PubMed2001

Ixodid ticks on white-tailed deer and feral swine in Florida.

A state-wide survey was conducted in Florida during the 1997-99 hunting seasons to examine white-tailed deer (Odocoileus virginianus) and feral swine (Sus scrofa) for potential indigenous vectors of the rickettsial agent of heartwater, Cowdria ruminantium. A total of 504 white-tailed deer and 166 feral swine was examined from 30 wildlife management areas across the state. Amblyomma maculatum, an experimental vector of C. ruminantium, was common on both deer and feral swine throughout the state. Of the collection of 3,169 ticks, 34.5% were Ixodes scapularis Say, 34.0% Amblyomma americanum (L.), 25.5% Amblyomma maculatum Koch, 5.8% Dermacentor variabilis (Say), 0.4% Ixodes affinis Neumann, 0.03% Rhipicephalus sanguineus (Latreille) and 0.01% Amblyomma auricularium (Conil). The only exotic tick collected was A. auricularium, which is found on armadillos in Central and South America and is not known to be associated with any disease. Overall, the most prevalent species on deer were I. scapularis (51.1%) and A. maculatum (35.8%), with A. americanum less prevalent (16.0%) and D. variabilis (3.0%) and I. affinis (1.9%) rare. On feral swine, the most prevalent species were I. scapularis (69.7%) and D. variabilis (56.9%), with A. maculatum (16.2%) and A. americanum (4.6%) less common. The geographic distribution of ticks differed significantly throughout the state. Both A. maculatum and Dermacentor variabilis were more prevalent on deer from southern Florida compared to northern and central Florida. In contrast, A. americanum were more prevalent in northern and central Florida but rare in southern Florida, and I. scapularis were more common in southern compared to northern Florida. These geographic differences may reflect differences in the risk of tick-borne diseases to domestic animals, wildlife and humans within Florida.

Animals↗
PubMed1994

Rickettsia rickettsii infection of cultured human endothelial cells induces tissue factor expression.

Microvascular thrombi underlie many of the clinical manifestations of Rocky Mountain spotted fever (RMSF), a disease characterized by Rickettsia rickettsii infection of vascular endothelial cells. Studies were designed to determine whether R rickettsii-infection of cultured human umbilical vein endothelial cells results in tissue factor (TF) induction, a process that could directly activate coagulation in infected vessels. Whereas uninfected endothelial cell cultures showed essentially undetectable TF mRNA and activity, both TF mRNA and activity were present after R rickettsii infection. TF mRNA levels were transient, peaking at 4 hours after the initiation of infection, whereas the peak of TF activity occurred at 8 hours. Induction of the TF response requires the intracellular presence of R rickettsii organisms, because uninfected rickettsia were ineffective and the response was blocked by inhibiting rickettsial entry using cytochalasin B. TF induction was not mediated by endothelial cell release of soluble factor, because no response was induced using culture medium conditioned by R rickettsii-infected cells. Furthermore, preadsorption of suspensions of R rickettsii with polymyxin B to remove contaminating lipopolysaccharide did not eliminate the TF response. Induction of TF in vital endothelial cells during R rickettsii infection could be the trigger for vascular thrombus formation of RMSF.

Cells, Cultured↗
PubMed1994

Size variation of the major immunodominant protein of Cowdria ruminantium.

An immunodominant response is made to a polypeptide of approximately 32 kDa in animals infected with the rickettsial pathogen Cowdria ruminantium. We show here using cultured strains of the rickettsia from different geographical areas that the apparent size of this polypeptide varies with strain origin. Changes in the primary structure between strains should be considered in the design of vaccines and diagnostic tests based on this antigen.

Animals↗
PubMed1999

[Epidemic typhus in Africa].

Epidemic typhus is caused by a small strictly intracellular virus named Rickettsia prowazekii, a member of the Rickettsial family. It is transmitted to man by the body louse, Pediculus humanus. Although now rare in Western countries, exanthematic typhus remains common in the Southern hemisphere due to poverty, inadequate clothing hygiene, and poor socioeconomic conditions. In Africa, outbreaks have historically occurred in Burundi, Rwanda, southwest Ouganda, and Ethiopia. The largest outbreak of epidemic typhus since the World War II was reported in Burundi where ongoing civil war since October 1993 has forced 10 p. 100 of the population of Burundi to live in cold, promiscuity, and malnutrition of makeshift refugee camps. The purpose of this report based on our two-year experience working with this unfortunate population is to describe the characteristics of this disease in Africa where the epidemic form had become rare until recently. Indeed political unrest as well as numerous civil wars are now epidmiological factors favorizing outbreaks of epidemic typhus at any time. This overview also provides an opportunity to recall epidemiological, bacteriological, and clinical aspects of typhus as well as diagnosis and treatment of the disease in the context of Africa.

Africa↗
PubMed1984

Rickettsia conorii isolated from Rhipicephalus sanguineus introduced into Switzerland on a pet dog.

A tick/rickettsial survey in a household near Geneva, Switzerland, revealed that 30 (40%) of 75 nymphs and adults of the brown dog tick, Rhipicephalus sanguineus, were infected with a rickettsial agent biologically and antigenically indistinguishable from R. conorii, the causative agent of boutonneuse fever. Introduced in 1979 from either southern France or Italy by the family's pet dog, the tick infestation had steadily increased until 1981 when control measures were initiated. During 1980 and 1981, four persons associated with the household's pet dog contracted a febrile illness diagnosed as boutonneuse fever.

Agglutination Tests↗
PubMed1990

Diagnosis of acute typhus infection using the polymerase chain reaction.

The first use of the polymerase chain reaction (PCR) for the diagnosis of an acute rickettsial infection is described. A primer pair derived from the 17-kDa antigen sequence of Rickettsia rickettsii gave specific amplification of a 434-base pair DNA fragment from the genome of Rocky Mountain spotted fever and endemic and epidemic typhus. The assay could detect as few as 30 rickettsiae. Detection of PCR-amplified DNA with a nonradioactive DNA probe confirmed an acute infection with Rickettsia prowazekii.

Acute Disease↗
PubMed1972

Lack of significant oncogenicity of biological products in hamsters.

A variety of biological products which included live and inactivated viral vaccines, inactivated rickettsial and bacterial vaccines, toxoids, and a multiple bacterial antigen product did not appear to be oncogenic for newborn hamsters following a single subcutaneous inoculation. The incidence of spontaneous tumors was approximately 4.7%, and this figure was not significantly altered by the inoculation of any of the test materials.

Adenoma↗
PubMed1990

Diagnosis of acute typhus infection using the polymerase chain reaction.

We used the polymerase chain reaction (PCR) for the diagnosis of an acute rickettsial infection. A primer pair derived from the 17-kDa antigen sequence of Rickettsia rickettsii amplified specifically a 434-bp DNA fragment from the genome of Rocky Mountain spotted fever and endemic and epidemic typhus. The assay was able to detect as few as 30 rickettsiae. Detection of PCR-amplified DNA with a digoxigenin-labeled DNA probe confirmed an acute human infection with Rickettsia prowazekii.

Acute Disease↗
PubMed2003

Mediterranean spotted fever in Portugal: risk factors for fatal outcome in 105 hospitalized patients.

Mediterranean spotted fever (MSF) is the most important tick-borne disease in Portugal. It is a notifiable disease and during 1989-2000 the annual incidence rate in Portugal was 9.8/10(5) inhabitants. Although recognized as a benign acute disease and treated mainly with ambulatory procedures, some cases are severe and fatalities have increased in the last few years. In 1997, MSF mortality became more evident in Beja, a Portuguese southern district, with a case fatality rate of 32.3% in hospitalized patients. Analysis of 55 variables regarding epidemiologic, clinical, laboratory, and therapeutic data of fatal and nonfatal MSF cases were compared to identify risk factors in 105 patients hospitalized in Beja District Hospital, between 1994 and 1998. It was statistically significant that the patients dying in 1997 were younger than those in other years. The risk of dying is statistically significant in those who presented with diabetes, vomiting, dehydration, and uremia. The interval between the onset of symptoms to administration of anti-rickettsial therapy was the same for all patients. Therapy delay, reported by some authors to be associated with mortality of MSF, was not a risk factor in our study. The patients who died in 1997 died faster than those in other years. The variables studied could not explain the higher mortality rates observed in our study. Although one may speculate that the pathogenic strain of Israeli tick typhus, isolated in 1997, could be responsible for this increase of fatality rate, inherited patient factors might also be strongly associated with mortality.

Anti-Bacterial Agents↗
PubMed2004

Quick control of bubonic plague outbreak in Uttar Kashi, India.

A localized outbreak of bubonic plague occurred in village Dangud (population 332), district Uttar Kashi, Uttaranchal, India in the second week of October 2004. 8 cases were considered outbreak associated based on their clinical and epidemiological characteristics; 3 (27.3%) of them died within 48 hours of developing illness. All the 3 fatal cases and five surviving cases had enlargement of inguinal lymph nodes. None of them had pneumonia. The age of the cases ranged from 23-70 years and both sexes were affected. No such illness was reported from adjoining villages. The outbreak was fully contained within two weeks of its onset by supervised comprehensive chemoprophylaxis using tetracycline. A total of approximately 1250 persons were given chemoprophylaxis in three villages. There was no clear history of rat fall in the village. No flea was found on rodents or animals. 16 animal serum samples were found to be negative for antibodies against F-1 antigen of Y. pestis. However, Y. pestis was isolated from two rodents (Rattus rattus and Mus musculus) trapped in the village. One case and three animal sera showed borderline sero-positivity against rickettsial infection. The diagnosis of plague was confirmed by detection of four fold rise of antibody titre against F-1 antigen of Yersinia pestis in paired sera of three cases (one of the WHO approved criteria of diagnosis of confirmed plague). This outbreak and the occurrence of earlier outbreaks of plague in Surat (Gujarat) and Beed (Maharashtra) in 1994 and in district Shimla (Himachal Pradesh) in 2002 confirm that plague infection continue to exist in sylvatic foci in many parts of India which is transmitted to humans occasionally. Thus, there is a strong need for the States to monitor the plague activity in known sylvatic foci regularly and have a system of surveillance to facilitate prompt diagnosis and treatment of cases to control the disease. This investigation highlights that with high index of suspicion the disease can be diagnosed early and mounting of supervised comprehensive response can prevent the disease to proceed to pneumonic stage where man to man transmission gets established and outbreak assumes larger dimensions.

Adult↗
PubMed2003

Spotted fever group rickettsiae in ticks from the Masai Mara region of Kenya.

We have identified for the first time Rickettsia africae, and the ticks that harbored them, in Kenya. A total of 5,325 ticks were collected from vegetation, livestock, and wild animals during two field trips to southwestern Kenya. Most were immature forms (85.2%) belonging to the genera Amblyomma or Rhipicephalus. The adults also included representatives from the genus Boophilus. Ticks were assessed for rickettsial DNA by a polymerase chain reaction (PCR) using primers for the spotted fever group (SFG)-specific rickettsial outer membrane protein A (rompA) gene, and positive amplicons were sequenced. While none of the immature ticks tested positive by PCR, 15.8% of the adult Amblyomma variegatum and less than 1% of the Rhipicephalus spp. were SFG positive. Sequences of amplified products were identified as R. africae. These findings extend the known range of R. africae.

Animals↗
PubMed2000

Imaging of rickettsial, spirochetal, and parasitic infections.

This article reviews the clinical signs, symptoms, and neuroimaging findings of the commonly known rickettsial, spirochetal, and parasitic infections (cysticercosis is covered elsewhere in this issue). Differential diagnoses and significant imaging characteristics are reviewed to help narrow the diagnostic possibilities. Several of the infections in this disparate group are not seen as commonly as they once were because of advances in early diagnosis, treatment, improvements in sanitation, and prevention of epidemics. Many of the infections, however, are endemic to certain parts of the world and are seen with increasing frequency in immunocompromised individuals.

Brain↗
PubMedDate not supplied

[Emerging and reemerging rickettsiosis in an endemic area of Minas Gerais State, Brazil].

This article describes a serological survey for rickettsiosis in the county of Novo Cruzeiro, Minas Gerais State, Brazil, in 1998, testing schoolchildren and dogs. Sera included 331 samples from schoolchildren from an endemic area and 142 samples from schoolchildren from a non-endemic area in the county. All children examined were healthy and had not reported clinical symptoms of Brazilian spotted fever prior to the serological survey. Some 35 children in the endemic area were reactive to Rickettsia rickettsiiby indirect fluorescent antibody (IFA) with a titer of 1:64, corresponding to 10.6%. Sera from 73 dogs were tested, showing seroreactivity (IFA 1:64) to Rickettsia rickettsi, Ehrlichia chaffeensis, and Ehrlichia canisin 3 (4.11%), 11 (15.07%), and 13 (17.81%), respectively. The results in schoolchildren and the presence of canine seroreactivity to Ehrlichiaspecies that are potentially pathogenic to humans suggests the risk of transmission of other Rickettsiaein the study area.

Animals↗
PubMedDate not supplied

Zoonotic infections as causes of hospitalization among febrile Bedouin patients in southern Israel.

A prospective 12-month study was conducted throughout 1998 to determine the frequency of selected bacterial zoonoses as causes of fever among hospitalized Bedouins in southern Israel. One or more zoonoses were diagnosed in 30 (27%) of 110 patients admitted with fever. Brucellosis was diagnosed in 9 (8%), rickettsial infections in 20 (18%), and ehrlichiosis in 2 (2%), one of whom had also evidence of rickettsial spotted fever infection. None of the patients was diagnosed with Q fever. Compared with patients without zoonoses, patients with zoonoses were younger (P = 0.01), fewer of them had underlying conditions (P < 0.02), they had a longer febrile period prior to hospitalization (P = 0.04), a significantly higher proportion had arthralgia (P = 0.02), rash (P = 0.03), and splenomegaly (P = 0.04) and a lower proportion had pathological findings on chest auscultation (P < 0.01). Patients with zoonoses were found to have more commonly anaemia (P = 0.03) and leucopenia (P = 0.02) compared to the rest of the study population. Of the 30 patients with zoonoses 60% were misdiagnosed and only 57% received adequate antibiotic treatment. Zoonotic infections are a common cause of fever in adult Bedouins living in southern Israel. Because of the non-specific features of these diseases they are often misdiagnosed. Blood cultures and multiple serological tests should be used in the investigation of fever in such patients and tetracycline should be considered for initial empirical treatment.

Adult↗