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PubMed1980

Volunteer studies of typhoid fever and vaccines.

A series of studies evaluated the efficacy of three categories of typhoid vaccines: killed organisms given parenterally and orally and living attenuated mutants given orally. Vaccinees and unvaccinated controls were challenged with a single strain of virulent Salmonella typhi. Control individuals with prior military service (i.e. mandatory parenteral immunization) were significantly protected compared to non-veterans. Clinical protection of vaccinees was greatest (87%) following oral immunization with a mutant strain lacking epimerase.

Administration, Oral↗
PubMed1988

Persistence of antibody titres three years after vaccination with Vi polysaccharide vaccine against typhoid fever.

After a single injection of purified Vi polysaccharide vaccine against typhoid fever, serum titres were followed in student volunteers by passive haemagglutination assay and by radioimmunoassay. Elevated Vi antibody titres were still present after 36 months. This preliminary study should be followed by further investigations on the extent and duration of protection provided by Vi vaccine, and on volunteers in endemic areas.

Adult↗
PubMed2006

Introducing Vi polysaccharide typhoid fever vaccine to primary school children in North Jakarta, Indonesia, via an existent school-based vaccination platform.

OBJECTIVES: To report results on coverage, safety and logistics of a large-scale, school-based Vi polysaccharide immunization campaign in North Jakarta. METHODS: Of 443 primary schools in North Jakarta, Indonesia, 18 public schools were randomly selected for this study. Exclusion criteria were fever 37.5 degrees C or higher at the time of vaccination or a known history of hypersensitivity to any vaccine. Adverse events were monitored and recorded for 1 month after immunization. Because this was a pilot programme, resource use was tracked in detail. RESULTS: During the February 2004 vaccination campaign, 4828 students were immunized (91% of the target population); another 394 students (7%) were vaccinated during mop-up programmes. Informed consent was obtained for 98% of the target population. In all, 34 adverse events were reported, corresponding to seven events per 1000 doses injected; none was serious. The manufacturer recommended cold chain was maintained throughout the programme. CONCLUSIONS: This demonstration project in two sub-districts of North Jakarta shows that a large-scale, school-based typhoid fever Vi polysaccharide vaccination campaign is logistically feasible, safe and minimally disruptive to regular school activities, when used in the context of an existing successful immunization platform. The project had high parental acceptance. Nonetheless, policy-relevant questions still need to be answered before implementing a widespread Vi polysaccharide vaccine programme in Indonesia.

Antigens, Bacterial↗
PubMed2004

Comparison of two combined vaccines against typhoid fever and hepatitis A in healthy adults.

A prospective, randomised, observer-blind, comparative study was performed in healthy adults with a new hepatitis A/typhoid combined vaccine, Viatim, and the marketed Hepatyrix vaccine. Both vaccines induced high levels of protective antibodies, but typhoid responses were higher and hepatitis A responses more rapid with Viatim compared with Hepatyrix. Both vaccines were well tolerated, no serious adverse events (SAEs) occurred, but more Viatim vaccinees had more mild or moderate local reactions (82.7%) than Hepatyrix (53.1%, p < 0.001). In this direct comparison Viatim induced more local reactions, but elicited a more rapid and higher immune response to both antigens than Hepatyrix.

Adolescent↗
PubMed2006

Cell-mediated immune responses in humans after immunization with one or two doses of oral live attenuated typhoid vaccine CVD 909.

CVD 909 is a novel live attenuated S. Typhi oral vaccine candidate derived from strain CVD 908-htrA which constitutively expresses Vi. Herein we investigated whether the genetic manipulations involved in modifying CVD 908-htrA altered its ability to induce potent T-cell immune responses (CMI) after a single dose (five subjects) and, in a separate trial, whether a second dose (eight subjects) further enhanced its immunogenicity. In these clinical trials we observed that CVD 909 immunization elicits a wide array of CMI, including cytotoxic T cells (CTL), IFN-gamma, TNF-alpha and IL-10 (but not IL-2, IL-4 or IL-5) production, and proliferation to S. Typhi antigens. However, the administration of a second dose did not result in increases in CMI. These results suggest that the genetic manipulations to constitutively express Vi did not adversely affect the ability of CVD 909 to elicit a wide array of CMI responses. These observations add impetus for the continuing evaluation of CVD 909 as a typhoid vaccine candidate.

Administration, Oral↗
PubMed2004

Postmarketing safety surveillance for typhoid fever vaccines from the Vaccine Adverse Event Reporting System, July 1990 through June 2002.

Vaccines against Salmonella enterica serotype Typhi are used for prophylaxis of international travelers and have potential use as counterbioterrorism agents. The Vaccine Adverse Event Reporting System (VAERS) cannot usually establish causal relationships between vaccines and reported adverse events without further research but has successfully detected unrecognized side effects of vaccine. We reviewed reports to VAERS for US-licensed typhoid fever vaccines for the period of July 1990 through June 2002. We received 321 reports for parenteral Vi capsular polysaccharide vaccine and 345 reports for live, oral, attenuated Ty21a vaccine, with 7.5% and 5.5%, respectively, describing death, hospitalization, permanent disability, or life-threatening illness. Unexpected frequently reported symptoms included dizziness and pruritus for Vi vaccine and fatigue and myalgia for Ty21a vaccine. Gastroenteritis-like illness after receipt of Ty21a vaccine and abdominal pain after receipt of Vi vaccine, which are previously recognized events, occasionally required hospitalization. Nonfatal anaphylaxis was reported after both vaccines. VAERS reports do not indicate any unexpected serious side effects that compromise these vaccines' use for travelers' prophylaxis.

Adverse Drug Reaction Reporting Systems↗
PubMed1992

Mechanism of the protective immunity against murine typhoid: persistence of Salmonella L forms in the liver after immunization with live-cell vaccines.

Live-cell vaccines of Salmonella typhimurium, either a sub-lethal dose of a wild-type (strain LT2) or a high dose of its two-heptose Rd1 mutant (strain SL1004), induced acquired resistance to murine typhoid, which remained 180 days after immunization. Growth of S. typhimurium as a bacillary form ceased between days 30 and 60 of immunization, but L forms of this bacterium colonized the liver (the mean number of L forms in the liver: 600 L-forming units) even at 180 days post-immunization. In contrast, a high inoculum of either a Ra mutant (strain TV148) of strain LT2 or S. schottmülleri 8006 sharing the same O antigenic components with those of S. typhimurium induced only a short-lived protection in proportion to the number of L forms in the liver, and the protective immunity was lost before day 180. However, there was no significant difference in the salmonella-specific T-cell responses among groups of immunized mice on day 180 of immunization. A lethal infection with strain LT2 in mice which had been immunized 75 days previously with living cells of strain SL1004 resulted in a rapid clearance of the challenge inoculum, together with a rapid elevation of anti-S. typhimurium antibody responses. Thus, the present data suggest that the long-lived immunity conferred upon live S. typhimurium vaccines is attributable to the colonization of this bacterium in the liver as L forms and the ability to colonize the liver as L forms is independent of the chain length of salmonella O-antigens.

Animals↗
PubMed1998

Patient compliance in the use of Vivotif Berna(R) vaccine, typhoid vaccine, live oral Ty21a.

BACKGROUND: Several live attenuated vaccines against bacterial enteric pathogens have recently been licensed. These include the Salmonella typhi Ty21a typhoid vaccine (Vivotif Berna(R) Vaccine) and Vibrio cholerae CVD103-HgR cholera vaccine (Mutacol Berna(R) Vaccine). They comprise a unique class of biologics in which patient compliance is required for their optimal use. This is of particular importance in the case of the Ty21a vaccine strain of which multiple doses are required. Furthermore, exposure to heat, concomitant use with antibiotics or antimalarial drugs, and timing of vaccination with respect to food intake can affect vaccine potency and/or efficacy. This study was conducted to determine the level of compliance among adult North American travelers and to evaluate compliance errors with respect to potential vaccine efficacy. METHOD: Questionnaires were provided to 1091 travelers at twelve travel clinics in the United States and Canada. The patients were requested to complete forms which asked questions relating to vaccine storage and usage, and to return them to the travel clinic. A total of 762 completed questionnaires were returned. RESULTS: Few compliance errors were made regarding proper storage of the vaccine. The most common compliance errors involved not taking all four capsules on alternate days (10%) and not taking all four doses of vaccine prior to departure (6%). CONCLUSIONS: Pretravel counselling was effective in obtaining a high compliance rate among adult travelers in the use of Vivotif Berna(R) Vaccine. The majority of compliance errors reported would not be expected to negatively impact upon vaccine efficacy.

Administration, Oral↗
PubMed2005

Comparison of the antibodies in lymphocyte supernatant and antibody-secreting cell assays for measuring intestinal mucosal immune response to a novel oral typhoid vaccine (M01ZH09).

Antibody-secreting cell (ASC) and antibodies in lymphocyte supernatant (ALS) assays are used to assess intestinal mucosal responses to enteric infections and vaccines. The ALS assay, performed on cell supernatants, may represent a convenient alternative to the more established ASC assay. The two methods, measuring immunoglobulin A to Salmonella enterica serovar Typhi lipopolysaccharide, were compared in volunteers vaccinated with a live-attenuated typhoid vaccine M01ZH09. The specificity of the ALS assay compared to the ASC assay was excellent (100%), as was sensitivity (82%). The ALS assay was less sensitive than the ASC assay at <or=42 spots/10(6) peripheral blood lymphocytes.

Administration, Oral↗
PubMed1982

Evaluation of two Salmonella typhimurium hybrids as challenge organisms in a system for the assay of typhoid vaccines.

A mouse-virulent Salmonella typhimurium hybrid (H42), which expresses the Salmonella typhi Vi antigen in addition to S. typhi O antigens 9 and 12, and a mouse-virulent S. typhimurium hybrid (H1), which expresses only the 9 and 12 antigens of S. typhi, were compared in their behavior as challenge organisms in a system developed to assay the protective capabilities of typhoid vaccines. Swiss-Webster white mice, vaccinated intraperitoneally with live Escherichia coli hybrids expressing the S. typhi O antigens 9 and 12, were significantly protected against death from intraperitoneal challenge with each of the S. typhimurium hybrid strains. Vaccination with an E. coli hybrid expressing the S. typhi Vi antigen in addition to O antigens 9 and 12 was seen to confer no advantage in protection against either S. typhimurium hybrid challenge organism over that obtained by vaccination with an E. coli hybrid expressing only the O antigens of S. typhi. However, a notable difference in the behavior of the two S. typhimurium hybrids was seen in mice vaccinated with the parent of the E. coli hybrid vaccinating strains, E. coli F464, which expresses no surface antigens common to either of these S. typhimurium hybrid challenge organisms. A nonspecific (with respect to the vaccinating strain) protective effect, believed to be associated with Vi antigen expression by the challenge organism, was seen against the challenge with S. typhimurium hybrid H42 after F464 vaccination, whereas no protection was conferred by F464 vaccination against the challenge with Vi-nonexpressing S. typhimurium hybrid H1. Inasmuch as neither S. typhimurium hybrid discriminates between the expression or nonexpression of the Vi antigen in a vaccinating strain, it is concluded that the Vi-nonexpressing S. typhimurium hybrid H1, which more clearly indicates the vaccine-specific protective role of the S. typhi O antigens and does not exhibit the nonspecific protection response of hybrid H42, is the better choice as challenge organism for this vaccine assay system.

Animals↗
PubMed1962

Passive transfer of immunity to typhoid by macrophages.

Saito, Kazuhisa (Keio University School of Medicine, Tokyo, Japan), Masayasu Nakano, Takehisa Akiyama, and Daizo Ushiba. Passive transfer of immunity to typhoid by macrophages. J. Bacteriol. 84:500-507. 1962.-Cultured peritoneal macrophages collected from mice which had been injected intravenously with intact macrophages of mice immunized with live vaccine were found to exert inhibitory action against intracellular virulent Salmonella enteritidis. This inhibition was quantitatively inferior to that exhibited by peritoneal macrophages from the donors, i.e., mice actively immunized with live vaccine. After an intravenous injection of P(32)-labeled macrophages into mice, almost no radioactivity could be recovered in the peritoneal exudate cells of the recipients; about 50% of the radioactivity was recovered from the liver, spleen, and mesenteric lymph nodes. Therefore, the inhibitory action of the recipient's peritoneal macrophages against intracellular multiplication was attributed to the capacity of the recipient's own macrophages and not to that of the donor's macrophages. Tissue-cultured macrophages from recipients of sonic-treated cells did not exhibit inhibition against intracellular, virulent S. enteritidis, although the recipients were resistant to intraperitoneal infection with the same strain.

Animals↗
PubMed2000

Typhoid fever in group travelers: opportunity for studying vaccine efficacy.

BACKGROUND: Typhoid fever (TF) is a rare disease among travelers to endemic areas, and little is known about its travel-related epidemiology. In addition, efficacy data on TF vaccines in travelers is scanty. During 3 months of 1994/95, six cases of TF were reported in The Netherlands among participants of four package tours to Indonesia provided by the same operator. The present study was designed to describe the epidemiology of TF in these groups, and to assess whether travel groups can be used for studying the efficacy of TF vaccines in travelers. METHOD: Questionnaire-based historical cohort study of participants of 4 groups that stayed in the same hotels along their tours (n=156). TF was defined as blood culture-confirmed Salmonella typhi infection. Submitted isolates were typed by antigen and phage typing. Immunization status was considered documented if ascertained by written records. RESULTS: Among 110 participants (71%), six cases of TF were identified (group specific attack rate AR 5.4%), three of which were from one travel group (AR 12.0%). There were no significant differences by age or sex. Three submitted S. typhi isolates showed three different types, two of which were in the same group. Eighty-three percent of respondents reported documented TF vaccination in the preceding 3 years. All cases occurred in recipients of the oral Ty21a vaccine (AR 10.2%, 95% CI 3.8-20.8%), but differences with nonvaccinees and recipients of the heat-inactivated whole cell or Vi-antigen polysaccharide vaccines were not significant. CONCLUSIONS: Although TF is rare in travelers, infections with different strains of S. typhi can occur in one travel group. Travel groups offer an opportunity for retrospective assessment of vaccine efficacy, provided that equal chance of exposure is largely guaranteed; case ascertainment is maximally specific and similar in the vaccine groups; vaccine status is ascertained accurately; and prior immunity by previous exposures to and use of antibiotics effective against the infection are excluded from, or controlled for in, the analysis.

Adult↗
PubMedDate not supplied

Compliance to live oral Ty21a typhoid vaccine, and its effect on viability.

BACKGROUND: Concerns have been expressed that in travelers the efficacy of the live oral Ty21a typhoid vaccine Vivotif could be lower than reported, maybe due to a lack of compliance. The purpose of this study was to examine the level of compliance with the recommendations regarding dosing, timing of dosing with respect to food intake, and storage. METHODS: Travelers were randomized into two groups: one received oral information only, and the second, a combination of oral and written information. Four criteria of compliance were applied to travelers: 3 capsules needed to be swallowed (criterion 1) on day 1, 3 and 5 (criterion 2), at least 1 hour before or 2 hours after a meal (criterion 3) and the vaccine had to be kept refrigerated (2-8 degrees C) (criterion 4). Compliance was evaluated using three different methods: a questionnaire, pill counting, and electronic monitoring using the Medication Event Monitoring System (MEMS). Storage conditions were checked by temperature tags, and viability of the vaccine was assessed by culturing the content of remaining capsules. RESULTS: The data of 115 travelers were analyzed. All the travelers took the 3 capsules. Compliance to all four criteria was complete in 68% of travelers according to the questionnaire, and 53% according to the MEMS (p =.05). Sixty-seven percent of all the doses intervals were of 48 hours +/- 6 hours, 12% being shorter than 36 hours and 7% longer than 60 hours. Eighty-seven travelers (76%) took their capsules on each alternate day. The method of information had no significant impact on compliance. Forty-two percent of tags showed exposure to temperature over 10 degrees C for more than 24 hours. Yet, no difference could be found in the viability of the vaccine compared with controls. CONCLUSIONS: Most travelers take their 3 capsules on alternate days, but many did not follow the other recommendations. Electronic monitoring of compliance provides more accurate results than questionnaires. Emphasis must be put on motivating the travelers to take the vaccine as recommended.

Administration, Oral↗
PubMed2005

Overlapping epidemiologies of hepatitis A and typhoid fever: the needs of the traveler.

Hepatitis A and typhoid fever are endemic infectious diseases in many parts of the world. They share a common, simple mode of transmission--the fecal--oral route-associated with poor hygiene. The low endemicity of both diseases in developed countries, and the rise in travel to exotic destinations for business and leisure, mean that increasing numbers of travelers are being exposed to infection. Effective, established vaccines are available against both diseases, and recently new formulations combining both vaccines in one injection have been licensed. We review the present epidemiologic situation for both diseases, to determine the necessity to routinely vaccinate travelers against both diseases.

Disease Outbreaks↗
PubMedDate not supplied

Changes in the lymphocyte cytoplasmic refractive index following typhoid vaccination.

The refractive index of the circulating blood lymphocytes (LCRI) of healthy young adults vaccinated with typhoid vaccine has been measured by immersion refractometry and phase contrast microscopy. A rise in the LCRI preceeds the rise in the antibody titre by two to three days. A more pronounced rise also occurred in one patient prior to a rejection crises following a kidney transplant.

Adolescent↗
PubMed1997

Typhoid fever: present and future.

Typhoid fever (TF), a systemic prolonged febrile illness, continues to be a worldwide health problem especially in developing countries where there is poor sanitation and poor standards of personal hygiene. The worldwide incidence of TF is estimated to be approximately 16 million cases annually with 7 million cases occurring annually in SE Asia alone. More than 600,000 people die of the disease annually. The pathogenesis of TF is beginning to be understood. The clinical features and diagnosis of TF are well known. New diagnostic methods have yet to gain universal acceptance. Traditional treatment with the first-line antibiotics (i.e. chloramphenicol, ampicillin and trimethoprim-sulphamethoxazole) though still being used in most developing countries are gradually being replaced with shorter courses of treatment with third generation cephalosporins or fluoroquinolones especially with the growing incidence of multi-drug resistant S typhi strains (MDR-ST). MDR-ST strains are particularly common in the Indian subcontinent; Pakistan and China. The presently available vaccines are far from satisfactory in terms of safety, efficacy and costs. Newer vaccines have been developed and are presently undergoing clinical trials in human volunteers.

Carrier State↗
PubMed1992

[Anti-typhoid vaccines].

There are three commercially available vaccines against typhoid fever: parenteral inactivated whole cell vaccine, oral live attenuated (strain ty21a), parenteral polysaccharide vaccine (capsular antigen-Vi). Their protective efficacy is 50 to 88% (inactivated vaccine), 50 to 96% (live attenuated vaccine) and 75 to 80% (polysaccharide vaccine). The frequency of notable adverse reactions with the inactivated vaccine justifies the use of the new vaccines.

Contraindications↗
PubMed1954

Proposed standard agglutinating sera for typhoid and paratyphoid A and B fevers.

The preparation of seven Standard Agglutinating Sera considered suitable to serve as international standard preparations for use in the serodiagnosis of typhoid and paratyphoid infections are described, and proposals are made for their further examination on a collaborative international basis.Details are given of antigenic materials and immunizing procedures which should suffice to enable substandards, based on the proposed International Standards, to be prepared locally.With the aid of the proposed Standard Agglutinating Sera it is possible to determine the "Standard Agglutinin Titre" of a serum under examination by any technique of the agglutination test, provided that a suspension of average sensitivity is employed.

Agglutination Tests↗