Plasmodium falciparum (P. falciparum) malarial degree of infection, termed as parasite density (PD), estimation is vital for point-of-care diagnosis and treatment of the disease. In this work, we present application of optical techniques: optical absorption and multispectral imaging for P. falciparum malarial byproduct (hemozoin) detection in human‐infected blood samples to estimate PD. The blood samples were collected from volunteers who were tested positive for P. falciparum infections (i-blood), and after treatment, another set of blood samples (u-blood) were also taken. The i-blood samples were grouped based on PD (+, ++, +++, and ++++). Optical densities (ODs) of u-blood samples and i-blood samples at blood absorption bands of 405 nm, 541 nm, and 577 nm showed different optical absorption characteristics. Empirical computation of ratio of the ODs for the blood absorption bands revealed reduction in the ODs with increasing PD. Multispectral images containing uninfected red blood cells (u-RBCs) and P. falciparum‐infected red blood cells (i-RBCs) on unstained blood smear slides exhibited spectrally determined decrease in both reflected and scattered pixel intensities and increase in transmitted pixel intensities with increasing PD. We further propose a linear classification model based on Fisher’s approach using reflected, scattered, and transmitted pixel intensities for easy and inexpensive estimation of PD as an alternative to manual estimation of PD, currently, the widely used technique. Application of the optical techniques and the proposed linear classification model are therefore recommended for improved malaria diagnosis and therapy.

中文翻译：

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恶性疟原虫疟疾副产物的光学鉴定用于寄生虫密度估计

恶性疟原虫（P. falciparum）疟疾的感染程度，称为寄生虫密度（PD），估计对于该疾病的即时诊断和治疗至关重要。在这项工作中，我们介绍了光学技术的应用：光学吸收和多光谱成像，用于检测人感染血样中的恶性疟原虫疟原虫（血生素），以估计PD。从测试为恶性疟原虫感染（i-血液）呈阳性的志愿者收集血液样品，并且在治疗后，还采集另一组血液样品（u-血液）。基于PD（+，++，+++和++++）对i血样本进行分组。的光密度（OD）在405 nm，541 nm和577 nm的血液吸收带上的u血样品和i血样品显示出不同的光吸收特性。根据血液吸收带的OD比率的经验计算显示，随着PD的增加，OD减少。多光谱图像包含未感染的红细胞（u -RBCs）和恶性疟原虫感染的红细胞（i未染色的血液涂片上的-RBCs表现出光谱确定的反射和散射像素强度的下降，以及透射像素强度随PD的增加而增加。我们进一步提出了一种基于费舍尔方法的线性分类模型，该模型使用反射，散射和透射的像素强度来轻松，廉价地估算PD，替代了目前被广泛使用的手动估算PD。因此，建议应用光学技术和提出的线性分类模型来改善疟疾的诊断和治疗。