SVIBOR - Project code: 3-01-176

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SVIBOR

SVIBOR - Collecting Data on Projects in Croatia

Project code: 3-01-176


Rickettsioses along the eastern coast of the Adratic sea


Main researcher: MOROVIĆ, MIRO (66165)


Assistants
Type of research: basic
Duration from: 01/01/91. to 12/31/95.
Papers on project (total): 10
Papers on project quoted in Current Contents: 1
Institution name: Opća bolnica, Zadar (85)
Department/Institute: Department of infectious diseases
Address: B.Peričića 5
City: 23000 - Zadar, Croatia
Communication
Phone: 385 (0)5724677 (455)
Fax: 385 (0)57312724
Summary: The investigation included three aspects:1.the overallseroprevalence of antibodies to Rickettsia conorii, Coxiellaburnetii and Rickettsia typhi;2. clinical characteristics of therickettsioases, and 3.investigation of ecological andentomological factors of the rickettsial diseases. Ad 1. A seroepidemiological survey was performed on a group of982 healthy blood donors and other individuals of variousprofessions, wtih no known history of any rickettsial diseases ortick bite, living in the Adriatic coastal region including Istra(Pula, Umag, Pazin, Labin, Poreč, Buje), n=85; Rijeka, n=90;island Pag, n=85; Zadar, n=380; Šibenik, n=ll9;, Split, n=99 andDubrovnik, n=l24. Sera were tested by indirect immunofluorescence assay (IFA). The results showed an endemic presence of the three rickettsiaein the area, with average prevalence rate for C.burnetiiantibodies of 23.67%, for R.conorii of 19.95% and for R.typhi of l3.1%. The highest prevalence rate of R.conorii and C.burnetiiantibodies was found in the Zadar area (4l.6% and 36.9%,respectively) and for R.typhi antibodies in the Split area(33.3%). In general, the lowest overall prevalence rate was notedon the island Pag (R.conorii l.2%, C.burnetii 2.3% and R.typhi3.5%) whoile antibodies to R.typhi were practically absent in thesera from Istra and Dubrovnik (O% and O.8%, respectively). Ad 2. The clinical spectrum of Mediterranean spotted fever (MSF)was prospectively evaluated in the North Dalmatian (Zadar) area. The classic clinical feature of MSF was predominant, with fever,maculopapulous rash and headache. The pathognomonic skin lesion"tache noire" was present in l6 cases (26.2%). We also noticed agrat number of unusual clinical manifestations as nodous, annularand infectious erythema, urticarial rash, oculoglandualrParinaud's syndrome, relapsing rash. The highest incidence of thedisease was in spring and summer, although it occurred i even in winter. The highest was noticed in children (24%). Inmost of cases the MSF intensity was moderate, but in threepatients it was severe. Particularly, a high proportion ofasymptomatic infections (seroconversion) in 30 of 86 patients(35%) with anamnesis of an antecendents tick bite must beemphasized. In 60 patients the diagnosis was also confirmed bydirect immunofluorescent assay, which proved to be enoughsensitive and specific, and reliable in early diagnosis of MSF. These results showed not only the width of clinical spectrum ofMSF in the Zadar area but also the possibility of an antigenicvariant of R.conorii that differs from those circulating in otherparts of Mediterranean basin. Besides, the results obtainedemphasize the problem of inadequate assesment of unreported/undiagnosed cases of MSF (in general, it has been estimated thatunlisted cases outnumbered recorded ones by nearly 3-4 to l). Ad 3. The investigation of ecological and entomological factors of rickettsial diseases showed that North Dalmatia has idealclimatic, biotic and abiotic conditions for maintainingrickettsiae, a very high seroprevalence of antibodies to spottedfever group of rickettsiae in dogs (55.5%) and sheep (77.2%) anda very high percentage of ticks infected with rickettsiae (thepredominant species of 10 different tick species wasRhipicephalus sanguineus, with infection rate of 70.5%).

Keywords: rickettsioses, seroepidemiology, clinical spectrum, Mediterranean spotted fever, Rickettsia conorii, ticks

Research goals: Rickettsiae are obligate intracellular bacteria which are closely associated with ticks, mites, lice, flies, chiggers. In recent years the number of new rickettsial strains isolated from humans or from ticks throughout the world has increased. At the same time the known areas of distribution of the well known rickettsial species have been changing. In the eastern coast of Adriatic sea, as in many parts of the world, rickettsioses had part due to difficulty in the clinical diagnosis and in part to the frequent lack of availability of specific laboratory diagnostic tests. Since l985, there has been remarkable increase in the number of reported cases of Mediterranean spotted fever along the Adriatic coast. In addition, our previous investigation documented the presence of antibodies to spotted fever group rickettsiae in healthy population too. Finally, the ecology of this area provides in principle excellent protection for rickettsial vectors and/or reservoirs. Specific Aims: 1. to determine the epidemiology of human exposure and illness caused by rickettsiae by means of specific serologic assays, 2. to characterize the clinical spectrum of rickettsioses along the eastern coast of Adriatic sea, particularly of Mediterranean spotted fever, and 3. to survey the ecosistem of coastal Croatia for the arthropod vectors and reservoirs of R.conorii by rickettsial isolation and identification and presence of antibodies in mammals. This study performed under this fellowship will formed a major contribution to the biomedical knowledge of the epidemiology, clinic and ecology of R.conorii and other rickettsiae in our region.

COOPERATION - INSTITUTIONS


  1. Name of institution: Medicinski fakultet Ljubljana,Mikrobiološki institut
    Type of institution: Economical/Production
    City: 61000 - Ljubljana, Slovenija

  2. Name of institution: Department of Pathology, University of Texsas MedicalBranch
    Type of institution: University/Faculty
    City: Galveston, USA
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