Point-of-care quantification of blood-borne filarial parasites with a mobile phone microscope

2015

Article référencé dans le Web of Science WOS:000354431600001

D'Ambrosio M. V., Bakalar M., Bennuru S., Reber C., Skandarajah A., Nilsson L., Switz N., Kamgno J., Pion Sébastien, Boussinesq Michel, Nutman T. B., Fletcher D. A.

Science Translational Medicine, 2015, 7 (286), p. 286re4 ISSN 1946-6234

Parasitic helminths cause debilitating diseases that affect millions of people in primarily low-resource settings. Efforts to eliminate onchocerciasis and lymphatic filariasis in Central Africa through mass drug administration have been suspended because of ivermectin-associated serious adverse events, including death, in patients infected with the filarial parasite Loa loa. To safely administer ivermectin for onchocerciasis or lymphatic filariasis in regions co-endemic with L. loa, a strategy termed "test and (not) treat" has been proposed whereby those with high levels of L. loa microfilariae (>30,000/ml) that put them at risk for life-threatening serious adverse events are identified and excluded from mass drug administration. To enable this, we developed a mobile phone-based video microscope that automatically quantifies L. loa microfilariae in whole blood loaded directly into a small glass capillary from a fingerprick without the need for conventional sample preparation or staining. This point-of-care device automatically captures and analyzes videos of microfilarial motion in whole blood using motorized sample scanning and onboard motion detection, minimizing input from health care workers and providing a quantification of microfilariae per milliliter of whole blood in under 2 min. To validate performance and usability of the mobile phone microscope, we tested 33 potentially Loa-infected patients in Cameroon and confirmed that automated counts correlated with manual thick smear counts (94% specificity; 100% sensitivity). Use of this technology to exclude patients from ivermectin-based treatment at the point of care in Loa-endemic regions would allow resumption/expansion of mass drug administration programs for onchocerciasis and lymphatic filariasis in Central Africa.

Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Entomologie médicale / Parasitologie / Virologie [052] ; Informatique [122]

AFRIQUE CENTRALE ; CAMEROUN

Fonds IRD [F B010064223]

fdi:010064223