External quality assessment of Giemsa-stained blood film microscopy for the diagnosis of malaria and sleeping sickness in the Democratic Republic of the Congo.
OBJECTIVE
To report the findings of a second external quality assessment of Giemsa-stained blood film microscopy in the Democratic Republic of the Congo, performed one year after the first.


METHODS
A panel of four slides was delivered to diagnostic laboratories in all provinces of the country. The slides contained: (i) Plasmodium falciparum gametocytes; (ii) P. falciparum trophozoites (reference density: 113,530 per µl); (iii) Trypanosoma brucei subspecies; and (iv) no parasites.


RESULTS
Of 356 laboratories contacted, 277 (77.8%) responded. Overall, 35.0% of the laboratories reported all four slides correctly but 14.1% reported correct results for 1 or 0 slides. Major errors included not diagnosing trypanosomiasis (50.4%), not recognizing P. falciparum gametocytes (17.5%) and diagnosing malaria from the slide with no parasites (19.0%). The frequency of serious errors in assessing parasite density and in reporting false-positive results was lower than in the previous external quality assessment: 17.2% and 52.3%, respectively, (P < 0.001) for parasite density and 19.0% and 33.3%, respectively, (P < 0.001) for false-positive results. Laboratories that participated in the previous quality assessment performed better than first-time participants and laboratories in provinces with a high number of sleeping sickness cases recognized trypanosomes more frequently (57.0% versus 31.2%, P < 0.001). Malaria rapid diagnostic tests were used by 44.3% of laboratories, almost double the proportion observed in the previous quality assessment.


CONCLUSIONS
The overall quality of blood film microscopy was poor but was improved by participation in external quality assessments. The failure to recognize trypanosomes in a country where sleeping sickness is endemic is a concern.
Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo .
Pierre
P
Mukadi
Philippe
P
Gillet
Albert
A
Lukuka
Benjamin
B
Atua
Nicole
N
Sheshe
Albert
A
Kanza
Jean Bosco
JB
Mayunda
Briston
B
Mongita
Raphaël
R
Senga
John
J
Ngoyi
Jean-Jacques
JJ
Muyembe
Jan
J
Jacobs
Veerle
V
Lejon
D000293:Adolescent; D000328:Adult; D001399:Azure Stains; D004396:Coloring Agents; D015023:Democratic Republic of the Congo; D003951:Diagnostic Errors / Q000517:prevention & control / Q000706:statistics & numerical data; D006801:Humans; D007753:Laboratories / Q000592:standards / Q000706:statistics & numerical data; D008288:Malaria / Q000175:diagnosis*; D008853:Microscopy; D010963:Plasmodium falciparum / Q000302:isolation & purification; D011785:Quality Assurance, Health Care / Q000379:methods*; D014346:Trypanosoma brucei brucei / Q000302:isolation & purification; D014353:Trypanosomiasis, African / Q000175:diagnosis*; D055815:Young Adult
D001399:Azure Stains; D004396:Coloring Agents