Patient description: An 8-year-old male presents in March to the ER with fever up to 39 C, dyspnea and cough for 2 days. He has just returned from a 5 day vacation in Colorado. Parents report that prior to the onset of fever and cough, he had loose stools. He denies upper respiratory tract symptoms. On examination he is in respiratory distress and has bronchial respiratory sounds on the left. A chest x-ray shows bilateral lung infiltrates.

Clinical trial eligibility criteria: eligible ages (years): 18.0-45.0,  Gastroenteritis Escherichia Coli Male or female ages 18-45, inclusive Provide written informed consent before initiation of any study procedures Healthy as judged by the Principal Investigator (PI) and determined by medical history, physical examination, and medication history Within 45 days of vaccination, have normal screening laboratories for white blood cells (WBC), hemoglobin (Hgb), platelets, absolute neutrophil count (ANC), sodium, potassium, chloride, bicarbonate, blood urea nitrogen (BUN), creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), prothrombin time (PT), partial thromboplastin time (PTT), International Normalized Ratio (INR), C-reactive protein (CRP), and fibrinogen as defined in Appendix B Have normal screening laboratories for urine protein and urine glucose Demonstrate comprehension of the protocol procedures and knowledge of study by passing a written examination (passing grade is at least 70 percent) Capable of understanding, consenting and complying with the entire study protocol including the inpatient period Female subjects must be of non-childbearing potential, (as defined as surgically sterile or postmenopausal for more than 1 year), or if of childbearing potential must be practicing abstinence or using an effective licensed method of birth control (e.g., history of hysterectomy or tubal ligation; use hormonal or barrier birth control such as implants, injectables, combined oral contraceptives, some intrauterine devices (IUDs), cervical sponges, diaphragms, condoms with spermicidal agents, or must have a vasectomized partner) within 2 months of vaccination and must agree to continue such precautions during the study and for 30 days after the Day 28 study visit. Male subjects must agree not to father a child for 90 days after the Day 0 study visit. A woman is eligible if she is monogamous with a vasectomized male Agrees not to participate in another clinical trial during the study period Agrees not to donate blood to a blood bank for 12 months after receiving the vaccine  Women who are pregnant or lactating or have a positive serum pregnancy test at screening or positive urine pregnancy test upon admission to inpatient facility Abnormal Vital signs, defined as Hypertension (systolic blood pressure >140 mm Hg or diastolic blood pressure >90 mm Hg) at rest on 2 separate days; or (heart rate <55 at rest on 2 separate days) Respiratory rate >17 Temperature >/= 38.0 C (100.4 F) or symptoms of an acute self-limited illness such as an upper respiratory infection or gastroenteritis within 7 days of administration of dmLT Active positive Hepatitis B, C, and Human Immunodeficiency Virus (HIV) serologies Have a positive urine drug screen Subjects who are unwilling or unable to cease smoking for the duration of the inpatient stay History of antimicrobial treatment in the 2 weeks before ingestion of dmLT Received previous experimental E. coli, LT, or cholera vaccines or live E. coli or Vibrio cholerae challenges; or previous infection with cholera or diarrheagenic E. coli Abnormal bowel habits as defined by fewer than 3 stools per week or more than 2 stools per day in the past 6 months