Question

Part 1 On Tuesday, November 3, 1970, the Center for Disease Control (CDC) in Atlanta received the weekly telegram of surveillance data from the Texas State Health Department. The telegram reported 319 cases of measles in the state during the previous week. In contrast, Texas had reported an average of 26 cases per week during the previous four weeks. In follow-up telephone calls, CDC learned from state health officials that 295 cases of measles had been diagnosed in the city of Texarkana, including 25 in children that were reported to have been previously immunized. An invitation to investigate the situation was extended to the CDC on November 4, 1970. An EIS officer departed for Texarkana early on November 5. Background Texarkana is a city of roughly 50,000 that straddles the Texas-Arkansas state line. Texarkana, Texas (Bowie County), had a population of 29,393 in the 1960 census; the population had been stable during the 1960s. Texarkana, Arkansas (Miller County), had a 1960 population of 21,088. Although Texarkana is divided by the state line, it is a single town economically and socially. Persons of all ages on both sides of town have frequent contact. Churches, physicians, offices, movie theatres, and stores draw people from both the Arkansas and Texas sides of town. People cross the state line to attend social functions such as football games and school dances. Many families have friends and relatives who visit back and forth on both sides of town. Private nurseries and kindergartens receive children from both sides of town. The two sides of Texarkana, however, do have separate public school systems and separate public health departments. Please answer the following questions and upload your document with your responses: Question 1: List the reasons to investigate a suspected outbreak. Which reasons may have prompted an investigation of this outbreak? Question 2a: What would be the initial steps of your investigation, i.e., the steps before trying to find additional cases? Question 2b: How might you look for additional cases? Question 2c: Once you collected information about the cases, how would you characterize the outbreak?

Answer 1

1. The reasons to investigate a suspected outbreak are 295 cases of measles had been diagnosed and 25 children who were previously vaccinated against measles also got affected by measles.

The most important prompted reason for investigation - children got infected with measles eventhough they were previously immunised.

2a.The initial step in the investigation even before trying to find out additional cases would be to identify and confirm suspected cases for isolation to enable concentration of efforts in containing the situation.

Isolation of affected individuals will help reduce spread of the virus to the rest of the population. Surveillance should be made in population who are at high risk for infection ,including schools and daycare centres. Laboratory confirmation should include obtaining specimens for virus characterization from infected individuals to allow identification of the involved strain and its origin . Notify WHO about the outbreak.(Guidelines for measles and rubella outbreak investigation and response in the WHO European Region)

2.bTo get additional cases, all the individuals who had been immunized before would be treated as suspected cases because some of the reported cases were those who received immunization previously.

Based on the clinical criteria, all individuals who exhibit any of the symptoms of the infection should be treated as a suspect and laboratory specimen examination should be made for confirmation.

2c. After collecting information about cases perform molecular analysis can be conducted to determine the genotype of the measles virus. Genotyping is used to map the transmission pathways of measles viruses. Genotyping is the only way to distinguish between wild-type measles virus infection and a rash caused by a recent measles vaccination(https://www.cdc.gov/measles/hcp/index.html).This will also help us to plan for further treatment .