[Modern principles of prevention of human transmitted infections].

According to information about ecology of agents of parasitic diseases with lousy-flea mechanism of contamination, mite natural diseases and experience of battle with them, we can make a conclusion: elimination of spongers in their natural environment, lousies and fleas by washing and disinfection is not effective. Alternative is implementation of insectoacaricides of new class, based on permethrins. These insectoacaricides are secure for environment and very effective towards arthopods. Method of non-termal preventing suction of arthopods is probed in military practice and other treatment-prophylaxis institutes. It is proposed to implement new insectoacaricides in form of spray cans as part of individual contrebiological drug-locker of every service man, acting in difficult epidemiological situation, caused by virus threat of lousy or flea infection, or by beforehanded provision by impregnated uniform or clothes.

Murine typhus--Hawaii, 2002.

Murine typhus, a zoonotic disease caused by Rickettsia typhi, is uncommon in the United States. Hawaii typically reports five or six cases annually; however, 47 cases were reported in 2002. This report summarizes clinical data for three of these cases and describes murine typhus activity in Hawaii during 2002 and control efforts of the Hawaii Department of Health (HDH). The high number of reported cases in 2002 underscores the need for community education to prevent murine typhus and an assessment of environmental factors that might contribute to local disease transmission.

Clinical and epidemiological observations regarding the 1998 Kauai murine typhus outbreak.

Five cases of murine typhus occurring on southwestern Kauai in 1998 are described, following an investigation by the Department of Health. Two cases also had concurrent leptospirosis. Recent habitat changes of peridomestic animals and their fleas may have increased the risk for developing murine typhus. Increased suspicion of typhus by island physicians and more aggressive rodent control activities are recommended.

Ownership of cats or dogs does not increase exposure to Rickettsia typhi.

In the United States, murine typhus (Rickettsia typhi) is endemic in southern California and South Texas. Evidence indicates the natural host/vector system is the opossum and cat flea, the most common flea on both cats and dogs, and speculation suggests that pet contact may pose a risk for R typhi exposure. Serum from 140 subjects was tested for rickettsial antibodies by an enzyme-linked immunosorbent assay that used an R typhi antigen. Each subject was asked about pet contact status and placed in one of the following groups: owners, non-owners but with regular contact (more than 3 times per week), non-owners with irregular contact (fewer than 3 times per week), or non-owners with no contact. Overall, 15.7% of sera were positive for antirickettsia IgG. Of owners or those with regular contact, 14 of 96 (14.6%) were seropositive, while 8 of 44 (18.2%) of non-owners or those with irregular contact were seropositive. A chi-square test showed no significant difference among these groups (P > .5). We conclude that pet ownership or regular contact with pets is not a risk factor for exposure to Rickettsia typhi.

[Immunogenicity of a chemical typhus vaccine and of a corpuscular radioantigen obtained from Rickettsia prowazekii]. / Immunogennost' khimicheskoi sypnotifoznoi vaktsiny i korpuskuliarnogo radioantigena, poluchennogo iz Rickettsia prowazekii.

The protective activity of chemical typhus vaccine and R. prowazekii corpuscular radioantigen (CRA) was studied. Guinea pigs were immunized with doses of 32 and 48 antigenic units. Antibody production was assayed in the complement fixation test. On days 7, 15, 21, 30 and 60 after immunization the animals were challenged with R. prowazekii introduced in an amount of 10(5) minimum embryonal infective doses (MEID). On day 30 some of the animals were challenged with 10(3) MEID of R. typhi. The results demonstrated that both preparations were highly immunogenic and capable of protecting most of the animals from 10(5) MEID of R. prowazekii. Immunity developed earlier after immunization with CRA. The guinea pigs immunized with CRA, purified in percoll density gradient, and challenged with 10(3) MEID of R. typhi on day 30 showed a high level of cross immunity. In all control animals high fever and periorchitis were observed.

Rickettsial vaccines: the old and the new.

In the past century vaccine development for prevention of rickettsial diseases has been prolific. However, in the past 20 years no new rickettsial vaccine has been manufactured and there are currently no new or old rickettsial vaccines licensed. Early rickettsial vaccines were difficult, expensive and very hazardous to produce. Molecular biology techniques of today are currently being used to develop new rickettsial vaccines that are standardized, inexpensive, nonhazardous and efficacious.

Isolation of species-specific protein antigens of Rickettsia typhi and Rickettsia prowazekii for immunodiagnosis and immunoprophylaxis.

A simple procedure for the selective isolation of the protective species-specific protein antigens (SPAs) of Rickettsia typhi and Rickettsia prowazekii was developed to permit use of the SPAs in the immunodiagnosis and immunoprophylaxis of typhus infections. Although the SPAs were readily extracted from lysozyme- or detergent-treated rickettsiae, as measured by rocket immunoelectrophoresis, other polypeptides were also present, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In contrast, both water and seven buffers, each at a 10 mM concentration and pH 7.6, were nearly equally effective in the selective release of the SPAs from whole cells by extraction for 30 min at 45 degrees C. High-ionic-strength buffers and MgCl2 abolished this SPA release, thus suggesting that divalent cations were important in the binding of the SPAs to the cell envelope. The efficacy of the dilute buffer extraction procedure for isolation of large amounts of SPAs was tested by further characterization of the supernatants obtained by centrifugation (200,000 x g) of two successive tris-(hydroxymethyl)aminomethane-hydrochloride buffer (Tris) extracts. With this procedure, between 10 and 15 mg of SPA was obtained from 100 mg of purified rickettsiae. Although low-molecular-weight ribonucleic acid fragments were released into the Tris extracts in significant amounts, only the SPAs were detected, in significant quantities, as measured by polyacrylamide gel electrophoresis and rocket immunoelectrophoresis. The Tris extracts contained the same major and minor SPA polypeptides as those observed previously in SPA preparations obtained by extensive diethylaminoethyl-cellulose column chromatography, but the Tris SPAs were more satisfactory antigens in an enzyme-linked immunosorbent assay.