The diagnosis of malaria: the role of the haematology analyzers as first level screening

Malaria is one of the three most common infectious diseases worldwide, and is caused mainly by four species of Plasmodium: P. falciparum, P. vivax, P. malariae and P. ovale. The disease is endemic in developing countries but it is also gradually involving Western Countries like Italy. Albeit in 1970 the World Health Organization has included Italy among the malaria-free countries, malaria has become the most frequently imported tropical disease. Microscopic examination of the peripheral blood smear is the gold standard for diagnosing malaria. Although this test is quick, cheap and readily applicable, it has also some drawbacks such as low sensitivity and the need of qualified personnel. Therefore, an effective screening test for detecting malaria in cases with low clinical suspicion or characterized by non-specific symptoms is increasingly necessary, especially in Countries where the disease is not endemic. A new generation of hematological analyzers, whose performance may be potentially useful for the screening of subjects with suspected malaria infection has made available. Many fully-automated hematological analyzers, using different techniques (optical-cytochemical, optical fluorescence, multiangle polarized dispersion and volume-conductance-scatter), can now identify the presence of the malarial parasites in peripheral blood, producing specific cell distributions. The blood count can hence be regarded as a new diagnostic opportunity in malaria infection, since it is one of the basic investigations performed in febrile patients, and is also a simple and fast test, that can be performed in virtually all clinical laboratories.