Helminths have profound effects on the immune response, allowing long-term
survival of parasites with minimal damage to the host. Some of these effects
"spill-over", altering responses to
non-helminth antigens or allergens. It is suggested that this may lead to
impaired responses to immunizations and infections, while conferring
benefits against inflammatory responses in allergic and autoimmune disease.
These effects might develop in utero, through exposure to maternal helminth
infections, or through direct exposure in later life.
To determine the effects of helminths and their treatment in pregnancy and in
young children on immunological and disease outcomes in childhood.
The trial has three randomized, double-blind, placebo-controlled
interventions at two times, in two people: a pregnant woman and her child.
Pregnant women are randomized to albendazole or placebo and praziquantel or
placebo. At age 15 months their children are randomized to three-monthly
albendazole or placebo, to continue to age five years. The proposed
designation for this sequence of interventions is a 2 X 2(x2) factorial
Children are immunized with BCG and against polio, Diphtheria, tetanus,
Pertussis, Haemophilus, hepatitis B and measles. Primary immunological
outcomes are responses to BCG antigens and tetanus toxoid in whole blood
cytokine assays and antibody assays at one, three and five years of age.
Primary disease outcomes are incidence of malaria, pneumonia, diarrhoea,
tuberculosis, measles, vertical HIV transmission, and atopic disease
episodes, measured at clinic visits and twice-monthly home visits. Effects
on anaemia, growth and intellectual development are also assessed.
This trial, with a novel design comprising related interventions in pregnant
women and their offspring, is the first to examine effects of helminths and
their treatment in pregnancy and early childhood on immunological,
infectious disease and allergic disease outcomes. The results will enhance
understanding of both detrimental and beneficial effects of helminth
infection and inform policy. Clinical Trials 2007; 4: 42–57.