Sporogonic cycle of Plasmodium falciparum in a human blood sample.

Abstract

A 62-year-old woman recently arrived from Angola to start treatment for a papillary adenocarcinoma of the endometrium presented to the emergency room complaining of asthenia and anorexia. Upon admission the patient was afebrile (patient temperature: 35.9°C-37°C). Laboratory data showed: hemoglobin 9.0 g/dL (reference value [RV]: 12.0-15.3 g/dL), leucocytes 5.74 × 109/L (RV: 4-11 × 109/L), platelets 129 × 109/L (RV: 150-450 × 109/L) alanine aminotransferase 39 U/L (RV: 0-33 U/L), aspartate aminotransferase 33 U/L (RV: 0-32 U/L), total bilirubin 1.20 mg/dL (RV: <1.20 mg/dL), γ-glutamyl transferase 47 U/L (RV: 0-40 U/L), lactate dehydrogenase 269 U/L (RV: 100-250 U/L) and c-reative protein 1676 nmol/L (RV: <47.6 nmol/L). A peripheral blood film was performed two to three hours after blood collection (EDTA container) and the following findings were observed: gametocytes (Image 1A), trophozoites (Image 1B,C [appliqué/accolé presentation]), macrogametocytes (sporogonic [Correction added on September 19, 2020, after first online publication: the incorrect word ‘esporogonic’ is changed to ‘sporogonic’ after original publication.] cycle) (Image 1D,E), exflagellated microgametocytes (Image 1F,G), microgamete (Image 1H (microgamete nucleus [arrow]), neutrophil inclusions (Image 1I,J), Döhle bodies (Image 1K,L) and macroplatelets (Image 1M) (May-Grünwald-Giemsa stain, original magnification x1000). A diagnosis of Plasmodium falciparum infection was made, with a parasitemia of 3%. In the natural life cycle of Plasmodium species the presence of the exflagellated microgametocyte, microgamete and macrogametocytes, shown here, occur in the female Anopheles species mosquito.1-3 In the case presented here the presence of these parasite forms could have been induced in vitro due to a decrease in temperature from 35.9°C-37°C (patient temperature) to 17°C-28°C (room temperature), and by a decrease in the dissolved carbon dioxide when the blood comes in contact with the atmospheric environment, and subsequent increase in pH to above 8.0.3, 4 All these environmental changes occurred due to a delay in sample processing, possibly mimicking the changes which occur in the mosquito's gut.1 The presence of microgametes in the peripheral blood film can pose a diagnostic dilemma, leading to a wrong diagnosis of co-infection, because they can mimic Borrelia species or even for an inexperienced observer Trypanosoma species. The distinction can be made since Borrelia species lack nuclei and frequently have a spiral shape, and Trypanosoma species have a kinetoplast and an undulating membrane. Microgametes can be also seen, erroneously, as an artifact. The presence of macroplatelets may pose a problem because they can give false readings on automated cell counters once they can be counted as erythrocytes.5 None. M.P.B.P.: performed the research, analyzed data and wrote the paper. J.M.C.: analyzed data and wrote the paper. Data sharing is not applicable to this article as no new data were created or analyzed in this study. Data sharing is not applicable to this article as no new data were created or analyzed in this study.