Hookworm infection may not benefit asthma patients
MedWire News: Results from an initial study suggest that experimental infection with hookworm larvae does not significantly improve bronchial responsiveness or other measures of disease control in patients with asthma.
Writing in the journal Clinical and Experimental Allergy, John Britton (University of Nottingham, UK) and team explain: “There is now substantial epidemiological evidence that intestinal parasite infection in general, and hookworm infection in particular, may protect against wheeze, asthma and other allergic disease.
“These findings raise the possibility that experimentally induced parasite infections may be able to contribute, directly or indirectly, to the development of new strategies for the management of asthma.”
In the first clinical trial of experimental hookworm infection in people with allergic asthma, the researchers assigned 32 patients, aged at least 18 years, with the respiratory condition to receive cutaneous administration of either ten Necator americanus larvae or placebo.
Airway responsiveness to inhaled adenosine monophosphate (AMP) was assessed at baseline and after 16 weeks. The primary outcome was the change in provocation dose of AMP required to reduce FEV1 by 20.0% (PD20AMP), with secondary outcomes including changes in several measures of asthma control and allergen skin sensitivity, and the occurrence of adverse effects.
The researchers found that mean PD20AMP improved by 1.49 doubling doses in the hookworm group compared with only 0.98 doubling doses in the placebo group, but the difference between the two groups was not statistically significant.
There were also no significant differences between the two groups regarding asthma symptom-free days (13.3% vs 8.3%) and symptom-free nights (12.6% vs 9.7%), and other measures of asthma control. Nor were there any significant differences between the groups regarding skin sensitization and adverse effects.
Britton and team conclude: “Experimental infection with ten hookworm larvae in asthma did not result in significant improvement in bronchial responsiveness or other measures of asthma control in this study.
“However, infection was well tolerated and resulted in a non-significant improvement in airway responsiveness, indicating that further studies that mimic more closely natural infection are feasible and should be undertaken.”
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By Mark Cowen