Investigating Typhoid Fever Pathogenesis (TYGER)

You are invited to take part in a study to investigate typhoid fever and how the typhoid bacteria causes disease.  The study is being run by the Oxford Vaccine Group which is part of the University of Oxford.

If you are aged 18 to 60 years old and are, in good health, then you may be eligible to take part in the study. We will provide reimbursement for your time, inconvenience and travel. The total study participation time is 12 months.


Typhoid fever is an infection caused by the bacteria Salmonella Typhi. Although typhoid fever is rare in the UK, it is a major problem in developing countries, affecting up to 22 million people and resulting in many deaths every year. Access to clean water and sanitation facilities could help to eradicate typhoid infection but this is difficult to implement in resource poor countries. Effective vaccines could help to control the spread to disease.  Currently the typhoid vaccines that are available are only moderately effective and no vaccine is licensed for use in young children. More research is needed to better understand typhoid so that we can develop better typhoid vaccines.

Study goals

In this study we aim to understand more about the Salmonella Typhi bacteria and how it causes illness. Specifically we want to understand the importance of a toxin produced by the typhoid bacteria, called the Typhoid Toxin. Our goals are to better understand typhoid fever, develop new diagnostic tests and contribute to development of new vaccines against Salmonella Typhi.

We will be undertaking a ‘challenge’ with two strains of the typhoid bacteria (Salmonella Typhi). Participants will be exposed to live Salmonella Typhi under tightly controlled circumstances, by asking them to swallow a drink that contains the bacteria. After the challenge we will closely monitor participants for a period of two weeks, treating participants with antibiotics as soon as they show any symptoms of infection. This process has been undertaken by participants in previous Oxford Vaccine Group studies since 2011.

We will use two strains of the typhoid bacteria. Half of the participants (20) in this study will be challenged with a ‘normal’ strain of the typhoid bacteria, called wild-type strain, which has been used in earlier challenge studies. The other half of the participants (20) will be challenged with a modified’ strain of the typhoid bacteria that is not able to produce the typhoid toxin, called the toxin-negative strain. Previous studies show that by giving a specific dose of the wild-type strain of Salmonella Typhi, 60% to 70% of people exposed to the bacteria will develop typhoid infection. If fewer people are infected with typhoid after receiving the toxin-negative strain (less than 60%), then this suggests that typhoid-toxin, specifically, is important in causing typhoid disease

Further Information

The Oxford Vaccine Group, University of Oxford, is based in the Centre for Clinical Vaccinology and Tropical Medicine in the Churchill Hospital site. This study has been funded by the Bill and Melinda Gates Foundation.

"What does the study involve?" "What will I have to do?" These are important questions.

If you are interested in finding out more, please read the information booklet

If you would like to arrange a screening appointment, please answer the questions below to see if you may be eligible. It is important for you to know that all answers are anonymous and kept completely confidential.

If you would like any further information regarding the study please contact us on:

Email, Tel: 01865 611400

Kind Regards,

The Oxford Vaccine Group

Study reference: 2016/03

Ethics reference: 16/SC/0358