Biology Reference
In-Depth Information
Future of Genetic Research on
Ascaris
Infection: Deep Sequencing to
Identify Rare Functional Variants
333
References
336
INTRODUCTION
Infections with roundworms (Ascaris lumbricoides) remain major public
health concerns in many areas of the world. Epidemiologically, A. lum-
bricoides is the most common of the soil-transmitted helminth infections in
humans, currently affecting over a quarter of the world's population
1,2
(see Chapter 13). The global impact of Ascaris infection has remained
remarkably constant even though effective anthelmintics are available.
Despite its worldwide distribution and long-term consequences for
human health, ascariasis is considered to be a neglected disease.
3
Even
among the soil-transmitted helminths themselves, Ascaris has been rela-
tively poorly studied.
2,4
The long-term health impact of Ascaris infection tends to be
underappreciated, perhaps because the disease occurs in areas of the
world also affected by more severe infectious diseases with very
apparent, immediate effects. However, infection with A. lumbricoides
can have both major short-term and subtle long-term effects on health.
Surgical intervention may be required to treat severe cases associated
with very high worm loads that can cause intestinal blockage.
5
The
more common, subtle consequences of infection for health are associ-
ated with deficits in cognitive and physical growth and devel-
opment.
2,6
e
8
For example, levels of Ascaris infection have been
associated with poor performance in school and on some types of
cognitive tests.
8
e
12
The association of Ascaris infection with deficits
in physical growth and development has been demonstrated
repeatedly.
7,13
e
16
In addition to the direct health impact of Ascaris infection, the disease
also may have consequences for responses to other infectious diseases.
For example, there is evidence that helminth infections can negatively
impact the immune response to infection with HIV and tuberculosis.
15,16
The consequences of Ascaris infection are complex, and must be
considered carefully. Recent studies have suggested that while Ascaris
infections have clear negative effects on risk for some infectious
diseases, they may be associated with decreased risk for malaria
19,20
(see
Chapter 4).
