[The diagnosis of malaria by the thick film and the QBC: a comparative study of both technics].
BACKGROUND
The diagnosis of paludism is important because of the severity of the clinical picture caused by Plasmodium falciparum, the increasing number of travellers to endemic zones and the emigration from these zones. A comparative study of the QBC techniques (staining with acridin orange and observation with ultraviolet light) and the thick film with Giemsa staining was carried out.


METHODS
The QBC and thick film were performed parallelly for 17 months in a total of 623 samples pertaining to subjects from endemic zones of paludism (emigrants, immigrants and travellers).


RESULTS
Of the 623 samples studied 49 were positive for paludism by both techniques. Ten were positive with only the thick film and six were positive only with QBC. The sensitivity of QBC versus thick film was 83% and specificity 98.9%. The time used to determine diagnosis with the QBC technique ranged from 6 to 12 minutes from withdrawal of the sample, while with the thick film the time spent was more than 2 hours. The cases positive by thick film and negative with QBC corresponded to patients with very low parasitation. The intensity of parasitation was difficult to determine quantitatively by QBC.


CONCLUSIONS
Although the QBC technique has the advantage of speed it is inexact with respect to the quantification of parasitemia. Moreover, it is less sensitive than the thick film in patient with very low parasitations and cannot thus substitute the thick film.
Cabezos
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J
Unidad de Enfermedades Tropicales e Importadas, Centro de Atención Primaria Drassanes, Barcelona.
Bada
J L
JL
D000349:Africa / Q000208:ethnology; D000818:Animals; D005069:Evaluation Studies as Topic; D006403:Hematologic Tests / Q000379:methods*; D006801:Humans; D008288:Malaria / Q000175:diagnosis* / Q000208:ethnology / Q000469:parasitology; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000208:ethnology / Q000469:parasitology; D016780:Malaria, Vivax / Q000175:diagnosis* / Q000208:ethnology / Q000469:parasitology; D010965:Plasmodium malariae; D012680:Sensitivity and Specificity; D013030:Spain; D014195:Travel
Diagnóstico de paludismo por gota gruesa y QBC: estudio comparativo de ambas técnicas.