Review for 10.1186/1471-230X-10-62 (2010)

Reviewer's report
Title:Helicobacter pylori in apparently healthy children aged 0-12 years in urban
Kampala, Uganda: a community-based cross sectional survey.
Version: 1Date:19 February 2010
Reviewer: Schalk W van der Merwe
Reviewer's report:
Evaluation manuscript: Helicobacter pylori in apparently healthy children aged
0-12 years in urban
Kampala, Uganda: a community-based cross sectional survey.
Hestvik, E. et al.
The authors assessed the prevalence of H. pylori in a cross sectional study of
Ugandan children using a novel stool antigen test.
Positive remarks:
This is a large cross-sectional study in an apparent healthy population. The
authors applied the appropriate statistical analysis tools to assess sample size, in
logistic regression analysis; the study was controlled at all levels including data
collection and in the processing of samples collected. The authors should be
commended for the thoroughness at which the study was conducted. The study
gives epidemiological data of H. pylori prevalence and distribution across age
and gender for children in Uganda.
Major critisims
1. The study assessing prevalence of H. pylori in poor communities is not novel
and many studies from South America, Asia and Africa previously confirmed
similar findings. The addition of a stool antigen test (compared to serology and
later breath testing) unfortunately does not add enough novelty to the paper.
Seminal work in this regard was done by various authors (Malaty et al. Lancet
2002, Parsonnet et al Jama 1999 ect..).
2 The authors used a logistic regression approach with the purpose of identifying
the predictor variables that contribute significantly to the response variable, in
this case H. pylori infection. Predictor variables in H. pylori infection can be
factors such as familial infection status, poor hygiene, social crowding, age, and
race. The authors used stool antigen positivity, a presence/absence method to
infer potential transmission pathways. Although logistic regression has been
used extensively to infer intrafamilial transmission and to identify factors that
contribute to the prevalence of H. pylori in communities, potential problems with
this approach exists. For instance the distinction between cause and effect may
remain difficult or impossible to resolve since:
a. Logistic regression studies merely indicate that the significantly correlated
factors are the main contributing factors only of those considered in a particular
study. In the present study known associations with poor socio-economic status
and overcrowding are confirmed. However due to the use of presence/absence
methods and not high resolution molecular methods no further insight can be
gained at the potential source/ reservoir of H. pylori within the community. This
draw back ultimately impacts on the usefulness of the data obtained in resolving
reservoirs of this infection from the community or within families. Important
potential factors such as maternal, paternal H. pylori status and H. pylori status
within different family members within a household have not been considered in
the study analysis. Indeed, a recent South African study showed, using high
resolution H. pylori sequence analysis, that multiple strains circulate within
individuals obtained in a similar environment confirming that H. pylori
transmission is also occurring horizontally between individuals and may thus
account for the high prevalence within certain social structures.
b. Recent studies that have indeed attempted to resolve H. pylori transmission
using high resolution molecular methods to infer transmission in African subjects
exists but have not been considered in this paper (Delport et al. Genetics 2006,
Schwarz et al. PLOS Pathogens 2008)
Conclusions
The study undertaken in Uganda unfortunately does not contribute further to our
understanding of the dynamics of H. pylori infection. I feel that this study will be
better suited for publication in an Epidemiology journal.
Declaration of competing interests:
I declare that I have no competing interests