Press release: Doctors to see if whooping cough bacteria can pass silently between close contacts

Doctors in Southampton are leading a pioneering European study to find out if the bacteria that causes whooping cough can be transmitted to a bedroom partner by someone who is carrying the infection but has no symptoms.

It is the second part of a £2.3 million project to develop a better vaccine to protect against the condition following a drop in the effectiveness of the current vaccine, which is offered to all babies in the UK but does not provide lifelong protection.

The research team at University Hospital Southampton, led by Professor Robert Read, have already discovered a person can live with the bacteria – known as Bordetella pertussis (B. pertussis) – without becoming unwell, meaning they could unknowingly transmit the infection.

The findings of the first phase of the study, published in the journal Clinical Infectious Diseases in October, explain why clinicians across the world are seeing an increase in sporadic outbreaks of the condition.

The first stage saw participants admitted to the NIHR Southampton Clinical Research Facility for 17 days – but this will be the first time volunteers will be inoculated with the bacteria and allowed to return home to monitor if they can pass on the infection silently to close contacts without causing them to develop symptoms either.

Whooping cough is a highly-contagious bacterial infection which is spread through the coughs and sneezes of an infected person.

It causes repeated coughing that can last for two to three months or more and affects around 16 million people every year worldwide, particularly in developing countries, causing around 200,000 preventable deaths in children.

Adults suffer a milder form of the disease compared to young children but can still have an unpleasant cough for up to three months, while babies under the age of six months can be vulnerable to severe and life-threatening complications.

“Our work in this area has already shown us this bacterium can exist silently in the noses and throats of healthy people which we now know is why we are seeing outbreaks of whooping cough throughout the world,” explained Prof Read (pictured), who is director of the NIHR Southampton Biomedical Research Centre.

“The result of this is that serious disease is occurring in those people who are not vaccinated or who had their vaccines a long time ago so we are in desperate need of a more effective vaccine.”

Prof Read said as the team had already established how much pertussis bacteria can be given to a healthy person without them becoming ill, the next stage is to find out whether or not the infection can then be passed to their bedroom partner without them developing obvious symptoms such as a cough.

“As B. pertussis is spread in the droplets produced when coughing or sneezing it can be transmitted from individuals to their close contacts and, in particular, to household members and those sharing a bedroom,” he said. “However, it is important to know if people who are infected but have no symptoms can also pass on the infection.

“We are asking participants for their bedroom contacts’ consent to be involved as there is a possibility that B. pertussis will be transmitted to them and they will become infected and we would like to monitor that to see if they also do not develop any symptoms.”

Participants will receive two doses of live bacteria via the nose and both them and their bedroom partner will receive antibiotics on day 14 and week 16 of the study to stop the infection leading to whooping cough disease. If symptoms start to develop before 14 days they will get the antibiotic treatment sooner.

“The aim of the challenge model is to introduce B. pertussis to participants via inoculation, but not to cause whooping cough disease,” explained Dr Hans de Graaf, a consultant paediatrician at Southampton Children’s Hospital and part of the study team.

“Although there is the possibility participants will benefit by acquiring a degree of immunity to whooping cough afterwards, the primary aim of the study is to help inform the development of vaccines to prevent it by learning more about the nature of the infection and the body’s immune response.”

The UK study forms part of a wider £24 million European project, PERISCOPE, funded by the Bill & Melinda Gates Foundation and the Innovative Medicines Initiative, involving experts from 22 institutions across 11 countries.

Participants will receive £1,000 reimbursement for their time. Anyone interested in taking part can call 023 8120 4989 or email UHS.recruitmentCRF@nhs.net.