V. Evaluation of Cross-Immunity against Type 1 Dengue Fever in Human Subjects Convalescent from Subclinical Natural Japanese Encephalitis Virus Infection and Vaccinated with 17D Strain Yellow Fever Vaccine
The many Americans returning from areas of endemic malaria require that most clinical laboratories be proficient in preparing blood films for examination for malaria parasites. Adequate thick films challenge laboratories not ordinarily involved in these studies. We describe a new method for preparing thick films, using saponin stromatolytic solution as the lysing agent. This method, combined with Wright stain or Wright-Giemsa mixtures, gives results equal to or superior to conventional methods of lysing combined with longer Giemsa staining times; it is also more suitable to the clinical laboratory not involved in malaria screening or numerous cases of malaria. The reagents required are inexpensive and used in almost all clinical laboratories. Slides prepared with saponin lysis require less time to prepare, especially when stained with automatic slide stainers. They contain less background debris, making examination easier and more accurate. When used as described, the saponin does not appear to lyse plasmodia.
Present address: U. S. Reynolds Army Hospital, Fort Sill, Oklahoma 73503.