RESEARCH SARS TRANSMISSION SARS-associated Coronavirus Transmission, United States Elmira T. Isakbaeva,* Nino Khetsuriani,* R. Suzanne Beard,* Angela Peck,* Dean Erdman,* Stephan S. Monroe,* Suxiang Tong,* Thomas G. Ksiazek,* Sara Lowther,*† Indra Pandya- Smith,* Larry J. Anderson,* Jairam Lingappa,* Marc-Alain Widdowson,* and other members of the SARS Investigation Group1 To better assess the risk for transmission of the severe acute respiratory syndrome–associated coronavirus (SARS-CoV), we obtained serial specimens and clinical and exposure data from seven confirmed U.S. SARS patients and their 10 household contacts. SARS-CoV was detected in a day-14 sputum specimen from one case- patient and in five stool specimens from two case-patients. In one case-patient, SARS-CoV persisted in stool for at least 26 days after symptom onset. The highest amounts of virus were in the day-14 sputum sample and a day-14 stool sample. Residual respiratory symptoms were still present in recovered SARS case-patients 2 months after illness onset. Possible transmission of SARS-CoV occurred in one household contact, but this person had also traveled to a SARS-affected area. The data suggest that SARS-CoV is not always transmitted efficiently. Routine collection and testing of stool and sputum specimens of probable SARS case-patients may help the early detection of SARS-CoV infection. Sly described as the clinical manifestation of infection evere acute respiratory syndrome (SARS) was recent- by a novel coronavirus (CoV), the SARS-associated CoV (SARS-CoV) (1–5). This syndrome was first recognized in February 2003 in Vietnam, but it was later realized that the first cases occurred in southern China in November 2002 (6,7). Subsequently, the infection rapidly spread through- out the world, and by July 2003, when the World Health Organization declared that the outbreak was contained, 8,437 cases and 813 deaths in 32 countries had been reported (8). As the outbreak developed, epidemiologic evidence suggested that SARS-CoV was transmitted by respiratory droplets or direct contact with infected patients and possi- bly by fomites (9–12). In certain circumstances, transmis- sion of SARS-CoV was particularly efficient and resulted in individual patients infecting large numbers of people *Centers for Disease Control and Prevention, Atlanta, Georgia, USA; and †McKing Consulting, Atlanta, Georgia, USA (referred to as “super-spreading events”), whereas in other situations, no secondary transmission was observed (13). A better understanding of the duration of SARS-CoV shedding and virus quantities in respiratory secretions, stool, urine, and other body fluids and of the risk factors for spreading illness to close contacts is critical to accu- rately assess the risk for transmission and to develop effec- tive control strategies. To that end, we obtained serial bio- logic specimens and clinical and exposure data for 5 to 10 weeks after onset of illness from seven laboratory-con- firmed U.S. SARS patients and their household contacts. Materials and Methods Participants We targeted 103 patients who met the Centers for Disease Control and Prevention’s (CDC’s) surveillance case definition for probable SARS (14). Of these patients, 7 (7%) with laboratory-confirmed SARS-CoV infection (antibodies to SARS-CoV were detected) were enrolled; 1Members of the SARS Investigation Group: J. McLaughlin (Alaska Division of Health); M. Romney, A. Kimura (California Department of Health Services); D. Dassey, B. Lash, D. Terashita (California-Los Angeles County Health Department); S. Klish (California-Orange County Health Care Agency); S. Cody (California-Santa Clara County Health Department); S. Farley (California-Contra County Health Department); S. Lea (California- Marin County Health Department); R. Sanderson (Florida Department of Health); J. Wolthuis (Georgia Division of Public Health); C. Allard (Mississippi Department of Health); B. Albanese (New Mexico Department of Health); B. Nivin (New York City Department of Health and Mental Hygiene); P. McCall, M. Davies (North Carolina Department of Health); M. Murphy, E. Koch (Ohio Department of Health); A. Weltman (Pennsylvania Department of Health); H. Brumund (Virginia Department of Health); C. Barton (Utah Department of Health); K. Whetstone (Southwest Utah Public Health Department); W. J. Bellini, S. Bialek, J. A. Comer, S. Emery, R. Helfand, T. Hennessy, A. James, A. LaMonte, E. C. Newbern, S. Scott, L. Simpson, A. Siwek, C. Smelser, L. Stockman, X. Lu, D. White (Centers for Disease Control and Prevention). Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 10, No. 2, February 2004 225