ARTIFACTS THAT MY BE CONFUSED WITH
MALARIA OR OTHER BLOOD PARASITES
Inexperienced microscopists may have difficulty in examining thin and especially thick film because of contaminating elements that can be accidentally present in stained samples. Such contaminating elements can be either bacteria, skin dirt, powder particles present on the slide, vegetable spores, yeast or moulds in the air; alternatively, they can be due to bacteria, moulds, protozoa or other contaminating substances present in the water used for sample staining. As already pointed out, it is necessary to pay a lot of attention in making thin and thick blood films: slides should be perfectly clean and preserved in closed cases to avoid any contamination; furthermore, the water used for stain dilution should be preserved in well stoppered containers in order to avoid a plentiful development of moulds and bacteria. Artifacts are usually superimposed on the preparation and, at microscopical examination, they can be refracting or positioned on a different focal plan. Sometimes it is possible to observe some reddish granules without the presence of cytoplasm and, even if some of these might be remnants of malarial parasites, their presence alone is not sufficient to consider the sample as positive. Platelets are probably the artifacts that are more commonly mistaken for malarial parasites: they can be identified as trophozoites when superimposed on red blood cells, confused with schizonts when clumped, or mistaken for merozoites or other parasitic stages when free. Even though platelets can have very heterogeneous shape and size, they do hardly display a real likeness with malarial parasites. As a general rule, “nothing must be diagnosed as a parasite if it can be interpreted as an artifact”. Last but not least, it’s important to remember that microscopic examination of stained slides can reveal other hematological parasites that, despite their morphological resemblance, should not be mistaken for malaria.