Pathophysiology

The clinical manifestations, laboratory abnormalities, and complications of the disease correlate with the underlying histopathology. Still, only few autopsy studies that give an accurate description of the pathologic effect of rickettsia on the various tissues exist. The main finding is a systemic endothelial injury, a lymphohistiocytic vasculitis affecting almost any organ, with consequent interstitial pneumonitis, interstitial myocarditis, interstitial nephritis, portal triaditis,...

Rickettsia bellii

In 1966, a rickettsial agent was isolated in embryonated chicken eggs from a triturated pool of Dermacentor variabilis ticks collected from vegetation in Arkansas. The isolate was identified as a unique species and named R. bellii (13). Rickettsial isolates, characterized as R. bellii y using immunofluorescence typing, have been recovered from various Ixodid and Argasid tick species, including D. andersoni, D. occidentalis, D. albopictus, Haemaphysalis leporispalustris, Ornithodoros...

References

Londres Broadway House, 1935 1-301. 2. Bozeman FM, Masiello SA, Williams MS, Elisberg BL. Epidemic typhus rickettsiae isolated from flying squirrels. Nature 1975 255(5509) 545-547. 3. Hardy A. Urban famine or urban crisis Typhus in the Victorian city. Med Hist 1988 32(4) 401-425. 4. Gelston AL, Jones TC. Typhus fever report of an epidemic in New York City in 1847. J Infect Dis 1977 136(6) 813-821. 5. Raoult D, Dutour O, Houhamdi L, et al. Evidence for...

Rickettsia Australis Queensland Tick Typhus

Queensland tick typhus (QTT) has been recognized as a disease since 1946 when the first cases were observed among Australian troops training in the bush of northern Queensland in eastern Australia. Bacteria were isolated from 2 of 12 infected soldiers (47). This agent was found to be a new SFG rickettsia (48) by serological methods, and was named R. australis in 1950 (49). Thereafter, QTT has been recognized along the entire eastern coast of Australia, east of the Great Dividing Range (50-52)....

Clinical Disease Incubation Period

Because nonengorged L. sanguineus mites are minute (e.g., < 1 mm), attach for only short periods to obtain blood (e.g., minutes to hours), and inflict a painless bite, patients almost never identify the actual infective exposure (127). In rare cases where an initial exposure is known with certainty, a primary lesion develops at the bite site within seven days, and systemic manifestations occur within 10 days, following the mite bite (4,99). Estimated limits of the incubation period range from...

Neorickettsia risticii

This ehrlichia causes equine monocytic ehrlichiosis or Potomac horse fever in horses. The consistent clinical features of Potomac horse fever are fever, depression, anorexia, and diarrhea (122,123). The fever is usually biphasic, whereby an initial increase in rectal temperature of TABLE 2 Natural Hosts, Vectors, and Reservoirs of Genus Ehrlichia limited duration (12-18 hours) may occur several days prior to the onset of depression and anorexia. The clinical course of the disease then...

General Organization Of The Different Genera In The Family Anaplasmataceae

To summarize the phylogenetic position of the family Anaplasmataceae including most recent published data, we constructed a concatenated phylogenetic tree with available sequences of the rrs, gltA, and groEL genes. Representative species which belong to Anaplasmataceae and of which rrs, gltA, and groEL sequences were available were used to construct the phylogenetic tree. The GenBank accession numbers of rrs, gltA, and groEL gene sequences used to construct the phylogenetic tree were as follows...

Wolbachia and Adverse Post Treatment Reactions

Adverse post-treatment reactions to filarial chemotherapy occur as a result of a systemic inflammatory response. In lymphatic filariasis, the severity of these adverse reactions is associated with increasing proinflammatory cytokine production and high pretreatment parasite burdens (59). These reactions, characterized by headache, fever, and myalgia, are similar to the acute inflammatory responses observed with bacterial infections (59). Analysis of plasma samples by PCR and immunoelectron...

Patient Demographics Seasonality and Risk Factors

Rickettsialpox has been described in patients of all ages, from infants as young as six months, to adults as old as 92 years (4,13). In most patient series, the disease occurs equally among males and females (6,10,11,24,116). Cases are documented from all months of the year. Epidemics of rickettsialpox in New York City and the Ukraine during the late 1940s were FIGURE 4 Reported cases of rickettsialpox in the Ukraine, by month, during 1949-1950. Source From Refs. 10, 1l6. notable for a...

Clinical Manifestations Of Epidemic Typhus

After an incubation period of 10 to 14 days, epidemic typhus begins abruptly. The majority of patients with epidemic typhus develop a malaise and nonspecific constitutional symptoms (anorexia, chills, headache, myalgias, arthralgias, and fever) (17). In a recent study in Burundi, a crouching attitude due to myalgia, named sutama, was reported (18). A cough is frequent, as well as confusion and stupor. There is no eschar of inoculation at the site of the lice biting. Most patients develop a skin...

Equine Ehrlichiosisequine Granulocytic Anaplasmosis

The etiological agent was first named E. equi, but is now recognized as a strain of A. phagocy-tophilum (1). The disease is common in northern California but has been reported across the United States and in Europe and South America. The vectors are Ixodes spp., in particular I. pacificus (black-legged tick) in California (15) and I. ricinus in Europe. Most infections are subclinical but in horses that develop a more severe vasculitis, clinical signs evolve over a number of days and include...

Wolbachia as a Drug Target for Filariasis

Soon after the rediscovery of Wolbachia in filarial nematodes, the targeting of Wolbachia was identified as a novel strategy to develop better antifilarial chemotherapy (72). Mass drug administration programs are currently ongoing, with a view to eliminating human filariasis (73). These programs are predominantly transmission control programs, in that the drugs used ivermectin, albendazole, and diethylcarbamazine (DEC) have limited adulticidal effects, and the adult worms are long-lived. In...

Coagulation and Bleeding

Patients with Rocky Mountain spotted fever and Mediterranean spotted fever develop a procoagulant state associated with endothelial injury, release of procoagulant factors, activation of the coagulation cascade resulting in generation of thrombin, platelet activation, increased fibrinolytic factors, and consumption of natural anticoagulants (47,48). Thrombocytopenia develops in 32 to 52 of patients with Rocky Mountain spotted fever and 35 of those with Mediterranean spotted fever, probably...

Microbiology and Pathogenesis

The ability to survive within neutrophils is a highly unique adaptation, and the mechanism by which A. phagocytophilum has achieved this niche is a matter of intense investigation (9,10). It is known that A. phagocytophilum substantially alters host neutrophil function, by in part promoting inflammation and recruitment of additional inflammatory cells that could serve as new hosts (11-13), while preventing substantial margination and tissue distribution to facilitate maximal bacteremia for...

Epidemiology Geographic Distribution

Rickettsialpox is a notifiable disease in New York City, and during 1989-2000, a median of one (range 0-10) confirmed case was reported each year by the city health department (13). Populations of the vector mites and rodent hosts are documented throughout the U.S.A. (Table 1), and various studies suggest that substantial rates of infection occur among inhabitants of other urban areas (90,91) however, every U.S. case series of rickettsialpox published during the last 50 years describes a...

Intracellular Traffic of Coxiella burnetii

The adaptation of internalized C. burnetii to acidic environment has so far been considered as a prerequisite for its survival and multiplication in contrast to other bacteria, which rather subvert phagosome maturation (47,48). The adaptation of C. burnetii to intracellular life is linked with acidic pH of its phagosome. Acidic pH allows the entry of nutrients necessary for C. burnetii metabolism (49), and also protects bacteria from antibiotics by altering their activity. Hence, when...

Cross Adsorption Assay

In order to identify the infecting rickettsiae by discriminating cross-reacting antibodies between two or more antigens, cross-adsorption assay has been successfully developed to patients with rickettsioses (11,61). A schema of this procedure is presented in Figure 3. First, the serum of the patient is mixed separately with the bacteria involved in the cross-reaction, and then tested against each of these antigens. Cross-adsorption results in the disappearance of both homologous and...

Ecology And Epidemiology Ecology

Ticks in the Ixodes genus are known vectors for A. phagocytophilum, and are also vectors of B. burgdorferi (Lyme borreliosis) and Babesia microti (human babesiosis) (37,43,44). The most important tick vector of A. phagocytophilum in North America is I. scapularis that is distributed broadly across the east to the midwestern region of the United States (45,46) a smaller region on the Pacific coast of northern California, Oregon, and Washington is endemic for I. pacificus that are also competent...

R conorii caspia Astrakhan Fever Rickettsia

Since 1972, cases of a febrile exanthema have been described in patients living in rural areas in Astrakhan, a region of Russia located on the Caspian Sea. Prospective surveillance during 1983-1989 identified 321 cases of Astrakhan fever. The number of cases increased each year, reaching 72 cases in 1988. Most patients were adults (94 ), specifically males (61 ), and occurred during summer months (85 , including 43 in August). The disease was similar to MSF however, the presence of a tache...

Ecology And Natural History Arthropod Transmission Liponyssoides sanguineus

R. akari is transmitted to several species of rodents by L. sanguineus, a hematophagous mesostig-matid mite in the family Dermanyssidae. Humans are not a regular component in the natural circulation of R. akari, and zoonotic transmission of this pathogen occurs only when a mite infected with rickettsiae is unable to locate its natural host and is forced to obtain a blood meal from a human host. R. akari has been isolated from various commensal and wild rodent species however, transovarial and...

The Causative Agent Rickettsia Prowazekii Bacteriology of R prowazekii

R. prowazekii (Fig. 2) belongs to the Rickettsiales order of which the members are short (0.8-2- m long and 0.3-0.5- m diameter), Gram-negative bacillary microorganisms that retain basic fuchsin when stained by the Gimenez method (33). Rickettsiae live only intracellularly, but not enclosed in a vacuole (34,35). The genome of 1.1Mb of R. prowazekii, consisted of a single circular chromosome, has been completely sequenced (36). FIGURE 1 Geographical distribution of louse-borne epidemic typhus...

Downregulation of the Immune Response

Interleukin-10 (IL-10) plays an antiinflammatory role in controlling the strongly activated immune response following clearance of rickettsial infection. The serum concentration of IL-10 in C3H HeN mice is elevated on day 10 after inoculation of R. typhi, but not at the peak of the bacterial load on day five or in convalescence on day 15 (34). On day 10, the rickettsial load is below the limit of detection, having been controlled by the immune response. Continued activation of antirickettsial,...

Severe Forms of Mediterranean Spotted Fever

Severe forms, including major neurological manifestations and multiorgan involvement, may occur in 5 to 6 of MSF cases (70,71). Complications and death are very rare in infancy (24,26,61). The mortality rate is usually estimated around 2.5 among diagnosed cases (1.50 in the last decade in Portugal, including 2.58 in 1997) (23,70). In Portuguese series of cases, the fatality rates were 1.2 to 10 (24,72,73). Classic risk factors for severe forms include advanced age, immunocompromised situations,...

Pathophysiology Of Rickettsial Infections Edema Hypovolemia and Sequelae

Alterations in normal physiology of the body associated with rickettsioses ensue from multifo-cal injury to the microcirculation and possibly the systemic effects of cytokines. Increased microvascular permeability leads to edema, hypovolemia, and hypotension (10). In severe cases, hypotensive shock results in ischemia. At the early stage of hypovolemia, perfusion of the brain is maintained by decreased perfusion of other organs. Reduced perfusion of the kidneys results in reduction in the...

Wolbachia and the Adaptive Immune Response Serology

Although antibody responses to a number of Wolbachia antigens, such as an aspartate amino-transferase and HtrA-type serine protease (62,63) have been reported, the antibody responses to the major surface protein, WSP, are the most well characterized. Anti-WSP antibody responses have been demonstrated in filarial infections of cats (64,65), dogs (66), rhesus monkeys (67), mice (68), and humans (55,68-70). Anti-WSP antibody responses have been associated with disease. In rhesus monkeys...

Cultivation

Isolation of rickettsiae is of great importance, as the ultimate goal is recovery of the bacterial agent from a patient or an arthropod vector. However, this approach is reserved to specialized laboratories with cell-culture facilities and equipped with biohazard facilities. Currently, R. rickettsii and R. prowazekii have been recognized as potential agents of bioterrorism. Thus, their isolation must be performed only in Biosafety Level 3 laboratories. Rickettsiae have been isolated using...

Systemic Manifestations

Patients with rickettsialpox generally experience sudden onset of fever, diaphoresis, lassitude, myalgias, and headache two to seven days following the appearance of the primary lesion (128). In patients who do not receive specific antibiotic therapy, these symptoms persist for approximately 7 to 10 days (116,127,128). Remittant fever and malaise are invariably reported. The usual peak temperature is 38 C to 40 C, although it may rise to 41 C (92,127). A headache, usually frontal and...

Clinical Suspicion

Although the advent of novel diagnostic tools, such as cell culture and molecular amplification, has dramatically improved the efficiency of diagnosing rickettsioses and ehrlichioses, it is important to consider that diseases such as RMSF caused by R. rickettsii and MSF caused by R. conorii have been initially described solely on the basis of clinical evidence. Careful clinical examination and epidemiologic investigation of patients with potential rickettsioses and ehrlichioses is critical....

Acute Q Fever

From our large series of acute Q fever cases, we have been able to stress the following facts the onset of the disease is generally sudden, which associates elevated fever (91 ), headaches (51 ), myalgias (37 ), arthralgias (27 ), and cough (34 ). Less frequent are rashes (11 ) and meningitis (leading to lumbar puncture) (4 ). Nonspecific biological findings are a throm-bocytopenia (35 ), elevated liver enzymes (62 ), and an elevated erythrocyte sedimentation rate (ESR) (55 ). Abnormal chest X...

Q Fever As A Bioterrorism Agent

Biological agents that might be used for bioterrorism have been categorized as A, B, or C (76). Class A agents are easily disseminated or transmitted from person to person, cause high mortality, might cause public panic and social disruption, and require special action for public preparedness. Category B agents are moderately easy to disseminate, cause moderate morbidity and low mortality, and require special enhancement of Centers for Disease Control's diagnostic capacity and disease...

Defective Immune Response in Chronic Q Fever

C. burnetii infection may become chronic in immunocompromised hosts. Nude mice that exhibit major impairment of cell-mediated immunity can develop a chronic infection (26). Corticosteroid treatment or whole body irradiation favors the occurrence of relapses in mice previously challenged by C. burnetii (27). The relapses may be associated with endocarditis when mice received cyclophosphamide (28). Pregnant mice infected with C. burnetii experience chronic infection associated with miscarriage,...

Differential Diagnosis

The differential diagnosis of a patient with an eschar encompasses various infectious and noninfectious syndromes, including trauma, spider bite, erythema gangrenosum, factitial dermatitis, herpes simplex, herpes zoster, aspergillosis, and several diseases caused by agents associated with bioterrorism (e.g., Francisella tularensis, Yersinia pestis, Burkholderia pseudomallei, and B. anthracis) (13,20,22,93). Occasionally, rickettsialpox may even mimic some sexually transmitted diseases. Shankman...

Rickettsia Honei Flinders Island Spotted Fever

An acute illness clinically resembling SFG rickettsiosis was described in 1991 by Stewart, the only medical doctor among approximately 1000 inhabitants on Flinders Island, a small island off the southeastern coast of Australia near Tasmania. Fever, headache, myalgia, slight cough, and a maculopapular rash gave the practitioner reason to suspect rickettsial infection. Serological analysis, including the Weil-Felix agglutination and rickettsial-specific immunoflu-orescence tests, suggested that...

Rickettsia Japonica Japanese Or Oriental Spotted Fever

The history of discovery of this disease emphasizes the important role of a single curious person interested by atypical cases. Between May and July 1984, the Japanese physician Mahara observed three patients with high fever and rash. All of them lived in the same rural area and had collected shoots from bamboo plantations on the same mountain. In two patients, an eschar was observed. General clinical signs resembled scrub typhus or tsutsugamushi fever. This well-known and studied zoonotic...

Rickettsia Slovaca Tickborne Lymphadenopathy And Dermacentorbornenecrosiserythemalymphadenopathy

Rickettsia

A novel SFG rickettsia was isolated in 1968 from D. marginatus ticks collected in Slovakia (104). Based on serological studies and C + G content, two strains were found to be close but not identical to R. sibirica and R. conorii (105). Another serologically similar strain was isolated in the former U.S.S.R., present-day Armenia, in 1974 (106). Thorough studies revealed that these strains differed from all prototype strains known by that time and a new species of SFG rickettsia, R. slovaca, have...

Biological Diagnosis Of Epidemic Typhus

The diagnosis of epidemic typhus is usually suggested by the presence of typical clinical findings such as fever, headaches, and skin rash in patients infested with body lice or in persons who are living in crowded, cold, and unhygienic circumstances. Thrombocytopenia and an increase of the hepatic enzymes may be observed particularly in severe cases. Typhus often occurs in clusters, but it may also occur as isolated illness. The diagnosis of epidemic typhus is based on serology with indirect...

Prospects for Vaccines Against Rickettsial Diseases

After recovery from a spotted fever or typhus rickettsiosis, patients and experimental animals develop solid immunity that prevents reinfection. Historically, killed whole rickettsial vaccines have ameliorated the outcome of rickettsial infection. A live attenuated vaccine against epidemic typhus effectively prevented the illness, but unfortunately was prone to reversion to virulence. Thus, past experience indicates that stimulation of protective immunity is entirely feasible. Subunit vaccine...

Pasture Fever And Tickborne Fever

In Europe, A. phagocytophilum transmitted transstadially by I. ricinus (castor-bean tick) causes pasture fever and tick-borne fever in domestic ruminants (20). Although A. phagocytophilum also occurs in the United States, clinical cases have not been reported in cattle and it seems these strains are of low pathogenicity in ruminants (21). Pasture fever occurs in dairy cattle that have over-wintered in barns and are turned out onto tick-infested pastures in spring. There is a severe drop in milk...

N helmintoeca and Other Species

N. helminthoeca causes a disease named salmon poisoning in dogs and wild Canidae. This name was given because the disease is acquired by eating salmon parasitized with Neorickettsia-infected flukes. Clinical findings of salmon poisoning are fever, anorexia, depression, dehydration, vomiting, and watery to bloody diarrhea. The fatality rate in untreated infected dogs approaches 90 (134,135). Nanopyetus salmonicola is a vector trematode of N. helmintoeca that is known to be a pathogen of salmon...

Tickborne Rickettsiae

Ticks are prolific vectors, with more recognized transmitted agents than any arthropod other than mosquitoes. All of the nearly 900 known species of ticks require blood for their development and reproduction. Clinically relevant ticks belong to either the Ixodidae (the hard ticks) or the Argasidae (the soft ticks) a third family, the Nuttallielidae, comprises a monotypic genus of soft ticks found in southern Africa and for which an association with a pathogenic agent has yet to be described....

Rickettsia helvetica

R. helvetica was first isolated in I. ricinus the vector of Lyme borreliosis in Switzerland in 1979 35,36 . Because transstadial and transovarial transmission of this rickettsia has been demonstrated in I. ricinus, this tick represents both a potential vector and natural reservoir of R. helvetica. No animal reservoirs were found, although wild deer were intensively studied 37 . R. helvetica has been identified in I. ricinus in many European countries, including France, Germany, Sweden, Hungary,...

Candidatus Rickettsia Marmionii

During 2003-2005, six patients from Australian states of Queensland four cases , Tasmania, and South Australia were diagnosed with an SFG rickettsiosis characterized by fever all patients , headache 83 , arthralgia 50 , cough 50 , maculopapular rash 33 , and pharyngitis 33 Fig. 12 . An eschar was reported in only one patient. Genetic analysis of an isolate obtained from a patient showed close similarity to, but distinction from, R. honei, with 99.0 , 99.7 , and 99.6 homology of the 17-kDa...

Polymerase Chain Reactionbased Detection

Molecular methods based on PCR have enabled the development of sensitive, specific, and rapid tools for both detection and identification of rickettsiae from various samples. Specific sample management must be used prior the tests. Blood must be held at ambient temperature until cells are sedimented and rickettsiae are sought in the leucocytes cell buffy coat. Fresh tissues are preferred for PCR. However, paraffin-embedded tissues and even slide-fixed specimens may be used 69 . PCR assays can...

Candidatus Rickettsia tarasevichiae

A novel rickettsial agent, provisionally called R. tarasevichiae was first identified 102 and subsequently isolated 103 in I. persulcatus in different regions of Russia. Prevalence varied from 10 to 50 and more. Interesting observation was made on its prevalence, which rises from Western Siberia regions toward Far East where it reaches 95 O. Mediannikov, unpublished data . Phylogenetically, this rickettsia is distant from other rickettsiae and the most similar species, although quite remote, is...

Epidemiology Of Q Fever In Humans

From its very beginnings in an abattoir in Australia, Q fever has spread worldwide. The only areas currently not reporting cases are Antarctica and New Zealand 6,7 . The predominant manifestations of Q fever, however, vary from country to country and sometimes even within a country. In Nova Scotia, Canada, and in the Basque region of Spain, pneumonia is the predominant manifestation of Q fever 8,9 , whereas in the Canary Islands and elsewhere in southern Spain the dominant features are fever...