A 51 year old patient presented to the emergency room with abdominal pain and fever. Fever was associated with diaphoresis, chills and headaches. Patient was in Tanzania for 3 months. She was admitted to the hospital while she was there for some unknown infection, details of which are not available.
CBC done revealed normocytic normochromic anemia with a hemoglobin of 9.2 g/dl and thrombocytopenia. Platelet count was 100 K/uL. On review of peripheral blood revealed presence of malarial parasite (ring forms).
Malaria is an infectious disease caused by Plasmodium parasites. These parasites are primarily spread by the bite of infected female Anopheles mosquitos. There are four main types of Plasmodium (P) species that infect humans:
- Plasmodium vivax and Plasmodium ovale, which cause a relapsing form of the disease, and
- Plasmodium malariae and Plasmodium falciparum, which do not cause relapses.
Malaria must be recognized promptly in order to treat the patient in time.
Microscopy (morphologic analysis) continues to be the “gold standard” for malaria diagnosis. Parasites may be visualized on both thick and thin blood smears stained with Giemsa, Wright, or Wright-Giemsa stains. Giemsa is the preferred stain, as it allows for detection of certain morphologic features (e.g. Schüffner’s dots, Maurer’s clefts, etc.) that may not be seen with the other two. Ideally, the thick smears are used to detect the presence of parasites while the thin smears are used for species-level identification. Quantification may be done on both thick and thin smears.
Various antigen kits are available to detect antigens derived from malarial parasites. These rapid diagnostic tests (RDT) offer a useful alternative to microscopy in situations where reliable microscopic diagnosis is not available.
-Neerja Vajpayee, MD, is the director of Clinical Pathology at Oneida Health Center in Oneida, New York and is actively involved in signing out surgical pathology and cytology cases in a community setting. Previously, she was on the faculty at SUNY Upstate for several years ( 2002-2016) where she was involved in diagnostic work and medical student/resident teaching.