Chapter 13

a. Public health surveillance is a method that a community has available to monitor the health among its population by detecting problems, communicating alerts as needed, guiding the appropriate response, and evaluating the effect of the response.

a. The epidemiological triad includes the host, agent, and environment. The greater the pathogenicity, the greater the ability of the agent to cause disease in a susceptible host. Pathogenicity is dependent upon the infectivity of the agent—its ability to invade the host, destroy host body cells, and produce toxins resulting in virulence, or severity of the infectious disease.

a. Measles is a highly contagious disease that is transmitted via airborne particles.

b. The epidemiological triad features the host, agent, and environment and describes the who, what, and where of the infectious process, while the chain of infection builds on this triad, including a portal of exit from the host, an environmental reservoir, transmission, and a portal of entry into a susceptible host. Pathogenicity refers to the potential ability of an agent to cause disease in a host.

a. Mantoux TST testing is the preferred test for children under the age of 5, but prior vaccination with bacilli Calmette-Guérin (BCG) may cause false positive reactions to the Mantoux TB skin test, in which case either QFT-Plus or T-Spot blood testing is recommended.

d. Since hepatitis C is transmitted by direct contact with infected blood, the primary prevention strategy to reduce the risk of transmission is to avoid sharing contaminated equipment, such as syringes and needles.

d. The signs of mild to moderate food poisoning are fever, diarrhea, stomach pain or cramps, and nausea or vomiting. The signs of severe food poisoning include fever higher than 102°F, bloody diarrhea, diarrhea for 3 days or more, frequent vomiting, and evidence of dehydration.

c. The rash of erythema migrans is erythematous, annular, and homogenous at the site of the actual tick bite, expanding over several days, often to sizes greater than 5 centimeters in diameter with a central clearing that develops as the rash expands, resulting a “bull’s eye” appearance. Erythema migrans occurs in up to 80 percent of those infected with Lyme, but the classic rash is not always present.

a. The CDC helps to track and investigate foodborne illnesses through the following surveillance systems: PulseNet, Foodborne Diseases Active Surveillance Network (FoodNet), System for Enteric Disease Response, Investigation, and Coordination (SEDRIC), and Foodborne Disease Outbreak Surveillance System.

b. Contact tracing is a means of secondary prevention to identify those at risk of infection or those already infected in order to isolate and treat them as early as possible to prevent the spread of the disease and to prevent complications in the client.