Immunization against rotavirus infection is recommended for all children beginning at 6 weeks of age, with the first dose by 14 weeks 6 days and the last dose by 8 months (see Chapter 94). Two typhoid vaccines are licensed in the United States: an oral live attenuated vaccine (Ty21a) for children 6 years and older, and a capsular polysaccharide vaccine (ViCPS) for intramuscular administration for persons 2 years and older. These are recommended for travelers to endemic areas of developing countries or for household contacts of S. typhi chronic carriers.
Families should be aware of the risk of acquiring salmonellosis from household reptile pets. Transmission of Salmonella from reptiles can be prevented by thorough hand washing with soap and water after handling reptiles or reptile cages. Children under 5 years of age and immunocompromised persons should avoid contact with reptiles.
The risk for traveler’s diarrhea, caused primarily by ETEC, may be minimized by avoiding uncooked food and untreated drinking water. Prophylaxis with bismuth subsalicylate (Pepto-Bismol) for adults (2 oz or two tablets orally four times a day) may be effective for prevention but is not recommended for children. Symptomatic self-treatment for mild diarrhea with loperamide (Imodium) and WHO oral rehydration solution is recommended for children at least 6 years of age and adults. Self-treatment of moderate diarrhea and fever with a fluoroquinolone is recommended in adults of at least 18 years old. Prompt medical evaluation is indicated for disease persisting more than 3 days, bloody stools, fever above 102° F (38.9° C) or chills, persistent vomiting, or moderate to severe dehydration, especially in children.
Lactobacillus acidophilus is a probiotic and reduces the incidence of community-acquired and antibiotic-associated diarrhea in children treated with oral antibiotics for other infectious diseases.
There are six primary hepatotropic viruses:Hepatitis A virus (HAV)Hepatitis B virus (HBV)Hepatitis C virus (HCV)Hepatitis D virus (HDV)Hepatitis E virus (HEV)Hepatitis G virus (HGV)
They differ in their virologic characteristics, transmission, severity, likelihood of persistence, and subsequent risk of hepatocellular carcinoma (Table 113-1). HDV, also known as the delta agent, is a defective virus that requires HBV for spread and causes either coinfection with HBV or superinfection in chronic HBsAg (hepatitis B surface antigen) carriers. HBV, HCV, and HDV infections can result in chronic hepatitis, or a chronic carrier state, which facilitates spread. The cause of 10% to 15% of cases of acute hepatitis is unknown.
HAV causes approximately half of all cases of viral hepatitis in the United States. Among U.S. children, approximately 70% to 80% of all new cases of viral hepatitis are caused by HAV, 5% to 30% by HBV, and 5% to 15% by HCV. The major risk factors for HBV and HCV are injectable drug use, frequent exposure
Table 113-1 Characteristics of Agents Causing Acute Viral Hepatitis HEPATITIS VIRUSES FEATURE HAV* HBV HCV† HDV HEV‡ HGV TTV, SEN-V Viral structure 27-nm ssRNA virus 42-nm dsDNA virus 30to 60-nm ssRNA virus 36-nm circular ssRNA hybrid 27–34 nm ssRNA virus 50to 100-nm ssRNA virus 30to 50nm ssDNA virus particle with HBsAg coat