Cases Of Rickettsiosis Research Articles

Protein candidates for the serodiagnosis of rickettsioses: 1

The laboratory diagnosis of rickettsioses is based on serology (reference method), cell culture and/or molecular tools. However, the main drawback of serology is its incapacity to provide identification of Rickettsiae at the level of species. The aim of this study was to propose the versatile protein markers able to discriminate the patients with murine typhus from those with Mediterranean spotted fever. We have cloned and expressed 20 proteins of Rickettsia prowazekii and Rickettsia rickettsii, respectively, using the GATEWAY approach. These recombinant proteins were screened by ELISA with sera of infected patients with Rickettsia typhi and Rickettsia conorii, respectively. We identified several potential markers which allowed infection due to R.typhi to be discriminated from those due to R.conorii. However, the values of test-operating parameters were not sufficient for its 'routine' clinical use. Our diagnostic test requires further optimization for be applied as a point-of-care strategy in the management of patients with suspected cases of rickettsiosis.

同時期に経験した日本紅斑熱とツツガムシ病の各1例

同時期に経験した日本紅斑熱とツツガムシ病の各1例

Multicenter GeoSentinel Analysis of Rickettsial Diseases in International Travelers, 1996–2008

We investigated epidemiologic and clinical aspects of rickettsial diseases in 280 international travelers reported to the GeoSentinel surveillance Network during 1996-2008. Of these 280 travelers, 231 (82.5%) had spotted fever (SFG) rickettsiosis, 16 (5.7%) scrub typhus, 11 (3.9%) Q fever, 10 (3.6%) typhus group (TG) rickettsiosis, 7 (2.5%) bartonellosis, 4 (1.4%) indeterminable SFG/TG rickettsiosis, and 1 (0.4%) human granulocytic anaplasmosis. One hundred ninety-seven (87.6%) SFG rickettsiosis cases were acquired in sub-Saharan Africa and were associated with higher age, male gender, travel to southern Africa, late summer season travel, and travel for tourism. More than 90% of patients with rickettsial disease were treated with doxycycline, 43 (15.4%) were hospitalized, and 4 had a complicated course, including 1 fatal case of scrub typhus encephalitis acquired in Thailand.

Tick-Borne Diseases in North Carolina: Is“Rickettsia amblyommii”a Possible Cause of Rickettsiosis Reported as Rocky Mountain Spotted Fever?

Cases of Rocky Mountain spotted fever (RMSF) in North Carolina have escalated markedly since 2000. In 2005, we identified a county in the Piedmont region with high case numbers of RMSF. We collected ticks and examined them for bacterial pathogens using molecular methods to determine if a novel tick vector or spotted fever group rickettsiae (SFGR) might be emerging. Amblyomma americanum, the lone star tick, comprised 99.6% of 6,502 specimens collected in suburban landscapes. In contrast, Dermacentor variabilis, the American dog tick, a principal vector of Rickettsia rickettsii, comprised < 1% of the ticks collected. Eleven of 25 lone star tick pools tested were infected with "Rickettsia amblyommii," an informally named SFGR. Sera from patients from the same county who were presumptively diagnosed by local physicians with a tick-borne illness were tested by an indirect immunofluorescence antibody (IFA) assay to confirm clinical diagnoses. Three of six patients classified as probable RMSF cases demonstrated a fourfold or greater rise in IgG class antibody titers between paired acute and convalescent sera to "R. amblyommii" antigens, but not to R. rickettsii antigens. White-tailed deer, Odocoileus virginianus, are preferred hosts of lone star ticks. Blood samples collected from hunter-killed deer from the same county were tested by IFA test for antibodies to Ehrlichia chaffeensis and "R. amblyommii." Twenty-eight (87%) of 32 deer were positive for antibodies to E. chaffeensis, but only 1 (3%) of the deer exhibited antibodies to "R. amblyommii," suggesting that deer are not the source of "R. amblyommii" infection for lone star ticks. We propose that some cases of rickettsiosis reported as RMSF may have been caused by "R. amblyommii" transmitted through the bite of A. americanum.

Rickettsia sibiricasubsp.mongolitimonaeInfection and Retinal Vasculitis

<i>Rickettsia sibirica</i>subsp.<i>mongolitimonae</i>Infection and Retinal Vasculitis

Rickettsia parkeriin Uruguay

<i>Rickettsia parkeri</i>in Uruguay

Rickettsioses and the International Traveler

The rickettsioses--zoonotic bacterial infections transmitted to humans by arthropods--were for many years considered to be oddities in travel medicine. During the previous 2 decades, however, reports of >450 travel-associated cases have been published worldwide, the vast majority being murine typhus caused by Rickettsia typhi, Mediterranean spotted fever caused by Rickettsia conorii, African tick bite fever caused by Rickettsia africae, and scrub typhus caused by Orientia tsutsugamushi. Most patients present with a benign febrile illness accompanied by headache, myalgia, and cutaneous eruptions, but severe complications and fatalities are occasionally seen. Current microbiological tests include culture, polymerase chain reaction, and serological analysis, of which only the latter method is widely available. Tetracyclines are the drugs of first choice and should be prescribed whenever a case of rickettsiosis is suspected. Preventive measures rely on minimizing the risk of arthropod bites when traveling in areas of endemicity.

Rickettsiosis caused by Rickettsia conorii in Uruguay.

The first three human cases of rickettsiosis caused by Rickettsia conorii in Montevideo, Uruguay were described in 1990. All of them showed an initial papulosquamous lesion on the scalp from a canine tick bite (Amblyomma triste). At the same time, fever and regional adenopathies were observed. Serological diagnosis was made by the indirect IgM immunofluorescent technique on glass smears of R. conorii (Biomerieux Laboratories, France). All patients had a benign disease course after been treated with oral tetracyclines. Other authors later developed clinical and serological studies for R. conorii rickettsiosis in a nearby county, confirming our original findings. The tache noir and a light exanthema were also noticed. We have seen several similar cases since that date. Most of them were from rural areas, and two presented with the classical tache noir and a maculopapular rash with severe symptomatology. A. triste, a South American tick with deep anthropophilia, appears as the usual transmitting vector of the disease in the country. A review of the literature reveals a very intriguing absence of similar cases in the Americas including the USA. New studies are necessary to resolve this issue. The possibility that a new species of rickettsia responsible for the disease in Uruguay is also considered.

Imported rickettsioses in German travelers.

Twenty-two cases of rickettsiosis imported to Germany (13 men, nine women, average age 42 years) in a 5-year period were analyzed retrospectively regarding the travel histories, symptoms and clinical findings, laboratory features and course of the disease. The two primary rickettsial diseases were boutonneuse fever (18 patients) and scrub typhus (three patients). One patient had murine typhus. The main symptom was fever in 91% followed by headache (64%), myalgia (40%), arthralgia (50%) and diarrhea (36%). The most frequent clinical finding was lymphadenopathy in 65%. Eschar was detectable in 55% of patients with Rickettsia conori infection and in one patient with Rickettsia tsutsugamushi infection. All patients with R. tsutsugamushi infection as well as 33% of the patients with R. conori infection had a macular exanthema. One patient with scrub typhus had pleural and pericardial effusions. Seventy-three percent had an increased ESR. Three patients had leucocytosis, three increased transaminases and two normochromic anemia. The incubation period for R. conori infection was 5 to 28 days (average 14 days), for R. tsutsugamushi infection 7 to 21 days (average 16 days). Twenty-one patients were treated with tetracycline or doxycycline, one with erythromycin. All patients were cured. One patient had a relapse. Due to the fact that the symptoms are often not characteristic and that the routine laboratory findings are of only marginal help, the diagnosis of rickettsial diseases is often not easy. A detailed travel history sometimes gives an important hint for diagnosis.