Study of susceptibility to bacterial gastroenteritis

There is a knowledge gap about the correlation between immune status and the
measure of exposure in relation to the risk of gastroenteritis by Campylobacter
or Salmonella. This knowledge is crucial to etiologic research and a whole
range of risk-assesments which are being performed in the Netherlands and the
rest of the world. These types of research are used to generate recomendations
for the government and commodity boards for meat, to decrease the risk of
Campylobacter and Salmonella infections.
Animal experiments show the great importance of the role of pathogenicity of a
strain and the immune status for Salmonella or Campylobacter at the time of
exposure.
Volunteer studies about the dose response relation between illness and exposure
to Campylobacter have been performed in the past. Naturally, these studies were
performed with adult persons, and with small numbers of people. In the majority
of the studies the immune status was unknown, and when the immune status was
known and positive at exposure, the outcomes were influences highly by the
immune status at exposure.
The dose-response relationship of Campylobacter and Salmonella in humans is in
fact nearly unknown. And the variability of this dose-response relationship
being subject to the pathogenicity of particular stains is even more unknown.

In case of food- or water related outbreaks of bacterial gastroenteritis, the
regular research of Municipal Health Services (GGD) and the Food and Consumer
Product Safety Authority (VWA) aims at control of the outbreak.
The aim of this project is to extend the regular datacollection of the GGD and
VWA, for scientific research regarding:
1. What is the dose-response relationship between exposure to Campylobacter /
Salmonella and gastroenteritis? (consumption and degree of contamination of a
product, in relation to complaints of gastroenteritis)
2. What is the role of immune status in the suscebtibility of a host for severe
infections by Campylobacter / Salmonella?
3. What is the role of certain genetic factors in the susceptibility of a host
for severe infections by Campylobacter / Salmonella?

The regular research of the GGD in case of food- or water related outbreaks of
bacterial gastroenteritis will be extended.

Possible participants are: all exposed people (symptomatically as well as
asymptomatically)

As soon as possible after exposure, participants fill in a questionnaire of 3
pages, about complaints and consumption of the incriminated foodproduct. And a
tube of blood (10 ml), a mouthscraping, and a fecal sample are collected.
However, participants who feel that the blood withdrawal is too much a burden,
can choose to skip the blood withdrawal.

After 3 weeks the participants will be approached by mail for the second
questionnaire about complaints. Participants who have given blood will be
approached by phone at 3 weeks and half a year after exposure, to ask whether
they are willing to participate in a second and third blood withdrawal.

Participation means: 2 x questionnaire, 1 x fecal sample, 1 x mouth scraping, 3
x blood withdrawal (10 ml).

Participants who feel that the blood withdrawal is too much a burden, can
choose to skip the blood withdrawal.

Participation and completion of all parts of the study will cost a time
investment of one hour per participant.