[The microwave oven for drying thick blood smears. Benefits and limits for microscopic observation of Plasmodium falciparum trophozoites and gametocytes].
The micro-wave oven permits a rapid drying of thick blood smears classically used for parasitological malaria diagnosis. In order to evaluate this type of drying on the microscopic reading, a study was carried out in an hyperendemic area of malaria with 382 asymptomatic volunteers of all ages. Two thick smears were made for each volunteer, one immediately dried with a micro-wave oven for one minute, the second dried in the open air without any intervention. A single microscopist examined all the thick smears. The observation of Plasmodium falciparum trophozoites differed significantly between the two methods, the prevalence was 50% by normal drying versus 41% by the micro-wave oven. The geometric mean of the trophozoite number for positive thick smears was significantly lower with the micro-wave oven. When the parasitological density with normal drying was lower than 200 trophozoites/microliter of blood, 54% of results were wrongly negative with the micro-wave oven. On the other hand, the observation of P. falciparum gametocytes was significantly facilitated after drying with the micro-wave oven; the prevalence was 8% with normal drying versus 12% by micro-wave oven. In conclusion, the use of the micro-wave oven for the drying of thick smears is not recommended for malaria diagnosis although it improves the observation and counting of P. falciparum gametocytes.
Le Goff
G
G
Institut français de recherche scientifique pour le développement en coopération (ORSTOM), Yaoundé, Cameroun.
Le Hesran
J Y
JY
Robert
V
V
D000818:Animals; D001769:Blood / Q000469:parasitology*; D005898:Glass; D006801:Humans; D008853:Microscopy; D008872:Microwaves; D010963:Plasmodium falciparum / Q000254:growth & development* / Q000302:isolation & purification*
Le four à micro-ondes pour le séchage des gouttes épaisses. Intérêt et limites dans l'observation microscopique des trophozoïtes et des gamétocytes de Plasmodium falciparum.