Active clinical trials for "Typhoid Fever"

This trial is aimed to evaluate the safety and immunogenicity profiles of a new Vi-CRM197 conjugate vaccine against S. Typhi in healthy human adults in comparison with the currently licensed Vi polysaccharide vaccine.

The purpose of this study is to evaluate the safety, immunogenicity, and compatibility of our Vi-rEPA conjugate administered to infants with their routine vaccinations. We propose to recruit 300 full term healthy newborns in Vietnam and randomly divide them to receive Vi-rEPA plus DTP, Hib-TT (not yet used in Vietnam) plus DTP, or DTP alone. Consent is obtained following interviews of mothers during prenatal visits, or after delivery. All vaccines will be administered at 2, 4, and 6 months. A booster of Vi-rEPA or Hib-TT conjugate will be administered at 12 months of age and reactions monitored at 6, 24 and 48 hours after each injection. Maternal and cord blood samples are collected during labor and at delivery. Blood will be taken at 7, and 12 months of age from all study infants and at 13 months from infants injected with Vi-rEPA or with Hib-TT at 12 months. The blood samples will be assayed for Vi, Hib, diphtheria, tetanus and pertussis antibodies. The levels of serum IgG anti-Vi elicited by Vi-rEPA administered to infants by the above schedule will be compared to those elicited by this vaccine in 2 to 5 year-olds in the efficacy trial conducted in Dong Thap Province, Vietnam.

Research studies have found a relationship between the immune system (how the body reacts to an infection) and the development of depression. As it is still unclear how they might be linked the investigators will use a typhoid vaccination to activate the body's immune system and will measure the response by looking at changes in sleep patterns.

The efficacy and immunogenicity of enteric vaccines have generally been found to be lower in children in the developed than in the developing countries. This has been observed with vaccines against cholera rotavirus, ETEC and typhoid vaccines. There are a number of factors that may contribute to such differences in vaccine "take rates" in children, e.g. breast feeding and nutritional status of the children might influence their immunogenicity and efficacy. Thus, breast feeding of newborn and young infants may adversely influence the immune response to vaccination, which might have more pronounced effect in developing than in developed countries. Breastfeeding has also been shown to interfere with the serum immune responses to rotavirus vaccine although this effect could be overcome by administering three rather than one dose of the oral rotavirus vaccine. Our recent study of Dukoral in Bangladeshi children aged 18 months or younger has shown that the response rates and the magnitude of responses improved when breast milk was temporarily withheld . Thus, administration of vaccines may have to be adjusted when given to breast fed children. Another factor that may affect the immunogenicity is the effect of zinc. Previous studies have shown that zinc enhances the immune response to cholera vaccine in participants > 2 years of age , a recent study also observed a similar effect in infants. In this research project, we plan to study a number of different factors that might influence the immunogenicity of the two licensed oral model vaccines, specifically the inactivated killed oral cholera vaccine, Dukoral, and the live oral typhoid vaccine, Ty21a. We will also identify strategies that might improve the immunogenicity of the vaccines. The main objective of our study is to identify immunization regimens that may improve the immunogenicity of the vaccines in young children, which could be subsequently in field trials in Bangladesh and other developing countries. Specifically, we will determine if: (i) interventions identified to enhance immune responses to Dukoral, including zinc supplementation, could also enhance the immune responses to Ty21a; (ii) these two vaccines are able to induce both acute and memory B and T cell responses, (iii) treatment with antiparasitic drugs prior to immunization could modulate the immune responses to cholera and typhoid vaccines; and (iv) examine if arsenic exerts a suppressive effect on the immunogenicity of these vaccines.

Enteric fever, an infection characterised by diarrhoea and rash, is most often caused by a bacteria called Salmonella enterica. After ingesting contaminated food or drink, the Salmonellae travel first to the gut, then the bloodstream, from where they can infect other parts of the body. Antibiotics are used to kill the bacteria, but with increasing rates of antibiotic resistance, this treatment is becoming less effective. Two Salmonella variants, Typhi and Paratyphi, cause over 30 million cases of enteric fever and more than 200,000 deaths per year, mostly in developing countries. While improved hygiene and sanitation should eventually eliminate enteric fever, reduction of the disease burden in the medium term is achievable through effective vaccination. Vaccines likely to be available for mass vaccination are effective only against those Salmonella strains that bear the Vi polysaccharide capsule protein. Strains that do not have these capsule proteins, or have no capsule, will not be affected by vaccination and could 'fill' the space vacated by the capsulated strains. Indeed, enteric fever caused by S. Paratyphi A which does not carry the Vi protein, has risen during the past decade and accounts for more than half of all cases in some areas. Thus it is important that effective vaccines are available to protect against infection by both capsulated and noncapsulated Salmonella enterica. To develop such vaccines, we need a complete understanding of the human immune response to both types, including the contribution of immunity in the gut and the bloodstream, immune response to bacterial surface proteins, and the role of antibodies. How much cross-protection there is between the types of typhoidal Salmonellae after natural infection or vaccination is not known, but this is critical to vaccine development. This project aims to fill in the knowledge gaps highlighted, by fully characterising the infection process and immune response in enteric fever.

The current study goal is to examine the effect of Cephalosporins, Azithromycin and the combination of both on typhoid fever therapy in endemic population. The investigator's hypothesize that the combination of azithromycin and ceftriaxone may prove superior to each drug, ceftriaxone or azithromycin, alone.

This is a Multicenter, observer-blinded, randomized, Active controlled, Phase 3 study in healthy 6 months to 45 years aged Nepalese at the time of the first vaccine dose. The study objectives are: I. Demonstrate non-inferiority of Vi-DT compared to Typbar TCV® as measured by seroconversion rates of anti-Vi IgG ELISA antibody titers, 4 weeks after single dose (pooled immunogenicity of three lots of Vi-DT) II. Demonstrate the equivalence of immunogenicity as measured by anti-Vi IgG GMT of three lots of Vi-DT vaccine 4 weeks after single dose.

Enteric fever is responsible for over 20 million illnesses and 200,000 deaths each year. S. Paratyphi A accounts for a substantial and increasing proportion of these cases, as high as 90% in some regions of Asia. There are currently no vaccines directed against S. Paratyphi A, although there some candidates in preclinical and phase 1 trials. This study is funded by the European Vaccine Initiative and the Bill and Melinda Gates Foundation. Paratyphoid is a human-restricted infection, for which there are currently no small animal models available. In order to further our understanding of the host-pathogen interactions, this study will develop a novel human challenge model in which to investigate this infection, using a recent successful typhoid challenge model as its template. Healthy subjects to ingest a dose of Salmonella enterica serovar Paratyphi A, strain NVGH308, after drinking a bicarbonate buffer. Intensive follow up over 14 days will establish whether each participant meets clearly defined criteria for diagnosis of paratyphoid infection. Statistical analysis will be performed on this outcome will determine if it consistently gives an attack rate of 60 to 75%. If this is not reached with the first cohort of 20 participants, the dose will be escalated and the process repeated. A maximum of 80 participants will be enrolled. Total follow up will be over the course of one year. Descriptive clinical and laboratory data collected from participant observations, samples of blood, faeces, urine and saliva will allow insights into the disease and the host response. These insights will forward our knowledge of paratyphoid disease and may help discover or develop diagnostic methods. This study is funded by the European Vaccine Initiative and the Bill and Melinda Gates Foundation. Paratyphoid is a human-restricted infection, for which there are currently no small animal models available. In order to further our understanding of the host-pathogen interactions, this study will develop a novel human challenge model in which to investigate this infection, using a recent successful typhoid challenge model as its template. Healthy subjects will ingest a dose of Salmonella enterica serovar Paratyphi A, strain NVGH308, after drinking a bicarbonate buffer. Intensive follow up over 14 days will establish whether each participant meets clearly defined criteria for diagnosis of paratyphoid infection. Statistical analysis will be performed on this outcome will determine if it consistently gives an attack rate of 60 to 75%. If this is not reached with the first cohort of 20 participants, the dose will be escalated and the process repeated. A maximum of 80 participants will be enrolled. Total follow up will be over the course of one year. Descriptive clinical and laboratory data collected from participant observations, samples of blood, faeces, urine and saliva will allow insights into the disease and the host response. These insights will forward our knowledge of paratyphoid disease and may help discover or develop diagnostic methods. Anticipating the development of a successful live challenge model through this study, there will be the possibility of evaluating novel paratyphoid vaccines that are currently in early clinical phase testing. This serves an important function because field trials in endemic areas are expensive and time consuming. Speeding up this process using our model will be of great benefit to endemic areas.

In a recent controlled study, the investigators explored cross-reactive immune responses against different Salmonella spp. in healthy volunteers immunized with either the oral (Vivotif® ) or parenteral (Typherix®) typhoid vaccines (ISRCTN68125331). In the present study immune responses will be studied in a group receiving both of these vaccines and in the previously immunized volunteers after booster immunization (same groups receive same vaccines 2-4 years after primary immunization).

Typhoid fever is an infection caused by the bacteria Salmonella Typhi (S. Typhi). S. Typhi causes disease principally in developing countries where communities do not have access to safe water or adequate sanitation. It is thought to cause illness in approximately 22 million people every year and up to 200,000 deaths, mostly in children. The bacteria are spread when faeces from infected individuals contaminate food and water sources. Symptoms of infection include headache, fever and general aches and pains. If not treated properly typhoid infection can lead to severe complications and even death. In this study the investigators aim to understand more about the S. Typhi bacteria and how S. Typhi causes a bloodstream infection after it has been ingested and passed into the gut. In spite of the extensive morbidity and mortality associated with bacterial blood stream infections (BSI), comparatively little is known about the pathogenesis. At a time of increasing antimicrobial resistance and a lack of new antimicrobial agents, understanding the pathogenesis of BSI is essential for efforts directed at prevention both of Salmonella Typhi and other bacterial species, particularly those that are restricted to humans.