Biology Reference
In-Depth Information
Fitting Transmission Models to Data
178
Dynamic Models of Infection and Transmission
180
Deterministic, Stochastic and Hybrid Approaches
181
Parasite Distribution and Density-dependent Processes
182
Age-structured Models
183
Modeling Treatment
184
Model Validation
185
185
Anthelmintic Resistance
186
Elimination
Conclusions
187
References
189
INTRODUCTION
Ascaris lumbricoides (Nematoda: Ascaridida), commonly called the
large intestinal roundworm, parasitizes the gastrointestinal tract of
humans. It is often referred to as a helminth, a term which encompasses
a large number of nematode and platyhelminth parasites. A. lumbricoides
is also a soil-transmitted helminth (STH), a group of human gastrointes-
tinal nematodes transmitted via direct contact with eggs or larvae in soil.
1
In addition to A. lumbricoides, the STHs of greatest public health impor-
tance are Trichuris trichiura (whipworm) and the hookworm species
Ancylostoma duodenale and Necator americanus. Approximately 1 billion
people are infected with at least one of these parasites.
1,2
The burden of
A. lumbricoides infection alone has been estimated as to cost anywhere
between 1.8 and 10.5 million disability-adjusted life years (DALYs) (see
Chapter 13).
3
A. lumbricoides, together with T. trichiura and hookworm, comprise
three of the 13 neglected tropical diseases (NTDs) of greatest public health
importance.
4
The term neglected refers to the lack of attention that has
traditionally been paid to these infections by the research, medical and
international funding communities alike. Reasons for this, in the case of
the STHs, include that the majority of disease burden is borne by the
world's most impoverished people, acute pathology is uncommon and
the physical, cognitive and economic effects of chronic long-term infec-
tion are difficult to assess.
1
However, in the context of the current
unprecedented momentum and commitment to NTD control,
5,6
embodied by the recent London Declaration against NTDs,
7
there are
renewed calls for research and development to be embedded at the core of
