The present study aimed to compare the diagnostic performance of different European
reference laboratories in diagnosing helminths and intestinal protozoa, using an ether-concentration
method applied to sodium acetate-acetic acid-formalin (SAF)-preserved faecal samples.
In total, 102 stool specimens were analysed during a cross-sectional parasitological
survey in urban farming communities in Côte d'Ivoire. Five SAF-preserved faecal samples
were prepared from each specimen and forwarded to the participating reference laboratories,
processed and examined under a microscope adhering to a standard operating procedure
(SOP). Schistosoma mansoni (cumulative prevalence: 51.0%) and hookworm (cumulative
prevalence: 39.2%) were the predominant helminths. There was excellent agreement (kappa
> 0.8; p < 0.001) among the reference laboratories for the diagnosis of S. mansoni,
hookworm, Trichuris trichiura and Ascaris lumbricoides. Moderate agreement (kappa
= 0.54) was found for Hymenolepis nana, and lesser agreement was observed for other,
less prevalent helminths. The predominant intestinal protozoa were Entamoeba coli
(median prevalence: 67.6%), Blastocystis hominis (median prevalence: 55.9%) and Entamoeba
histolytica/Entamoeba dispar (median prevalence: 47.1%). Substantial agreement among
reference laboratories was found for E. coli (kappa = 0.69), but only fair or moderate
agreement was found for other Entamoeba species, Giardia intestinalis and Chilomastix
mesnili. There was only poor agreement for B. hominis, Isospora belli and Trichomonas
intestinalis. In conclusion, although common helminths were reliably diagnosed by
European reference laboratories, there was only moderate agreement between centres
for pathogenic intestinal protozoa. Continued external quality assessment and the
establishment of a formal network of reference laboratories is necessary to further
enhance both accuracy and uniformity in parasite diagnosis.