Abstract
In a study of the factors underlying continued growth and reproduction of malaria parasites (Plasmodium vivax) in blood cells removed from the human host, Bass and Johns 1 found that the addition of 0.5% of dextrose to human blood before defibrination apparently prevented an endosmosis into the parasitized corpuscles of toxic substances present in normal serum that quickly destroyed the parasites at body or other temperatures. That by the addition of dextrose the parasites continued their asexual reproduction at a rate directly dependent upon the temperature, up to a maximum of 40°C.
Confronted with the necessity of preserving and transporting blood containing tertian malaria parasites, I have extended these observations on dextrose content and temperature most conducive to prolonging the viability and consequent infectivity of such parasites.
Blood collected from patients presenting the symptoms of therapeutic “inoculation” malaria was first studied daily in stained preparations of defibrinated blood containing 0.5% to 2% of previously added dextrose, and kept at temperatures of —5 to + 15°C. Two such experiments conclusively revealed the longest survival of parasites, as shown by normally stained chromatin and protoplasm, in bloods containing 1% of dextrose and when kept at exactly 0°C. In both instances apparently viable parasites could be demonstrated with ease until the tenth day. Dead and dying parasites, as shown by their staining reactions, were most numerous in the higher temperatures with the passage of each 24 hour period.
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