Detection of Rickettsia rickettsii and Rickettsia sp. in blood clots in 24 patients from different municipalities of the state of São Paulo, Brazil - Gehrke, Flávia Sousa; Nascimento, Elvira Maria Mendes do; Souza, Eliana Rodrigues de; Colombo, Silvia; Silva, Luiz Jacintho da; Schumaker, Teresinha Tizu Sato (Annals of the New York Academy of Sciences, 2006)