The In Vivo Diagnosis of Malaria: Feasibility Study Into a Magneto-Optic Fingertip Probe

An in-depth analysis is presented into the feasibility of implementing a new magneto-optic test diagnostic for malaria in the form of a noninvasive finger probe. The diagnostic principle quantifies the malaria pigment hemozoin concentration in the blood stream by measuring the fractional change in transmitted optical intensity arising from the Cotton-Mouton effect on application of a magnetic field. Hemozoin is, to varying degrees, responsive to probing in this manner whether free in the blood plasma following lysis or, more commonly, contained in intracellular vacuoles of erythrocytes or leukocytes. Measurements made on living tissue and sophisticated phantoms, which mix solid and liquid phase media to mimic fingertip physiology, demonstrate that hemozoin concentrations less than 0.02 μg/ml may be readily detectable when blood, caused to pool in the capillary loop arterioles of the extensively vascularized nail bed, is interrogated through the fingernail. On conservative assumptions regarding the relationship between hemozoin production and parasitemia and taking account of the effect of locale on hemozoin responsivity the study indicates that an instrument built on this premise may in principle offer rapid non-invasive detection of malaria at parasitemia levels below 100 parasitized red blood cells per ml.