Outbreak Investigations and Control Measures Background Local and state public h

Question

Outbreak Investigations and Control Measures

Background

Local and state public health authorities are involved in many disease outbreak investigations each year. Whether, or how extensively, to investigate a given outbreak is determined by a combination of factors. Some of the factors that led the North Carolina Division of Public Health (NCDPH) to investigate in the outbreak described in the MMWR article were (i) the severity of the disease, hemolytic uremic syndrome (HUS), that can result from Escherichia coliO157:H7 infections in children, and (ii) the size of the potentially exposed population (~800,000 people attended the State Fair in 2004).

Although E. coli O157:H7 can spread from person to person (referred to as secondary transmission in the article), this generally can be prevented through rigorous attention to personal hygiene. There is no prophylaxis or treatment, other than supportive care, for E. coli O157:H7 infection. Because the outbreak of E. coli O157:H7 infection associated with the State Fair was due to a common source exposure, and the outbreak was not detected until after the end of the fair, in this instance there was no opportunity to implement control measures to stop the outbreak. Instead, the motivation for the investigation, and the case-control study, was to identify the source of the pathogen, and understand the risk factors for infection. With this information in hand, control measures were recommended that should prevent a similar outbreak from occurring again in the future.

Activity

Read the MMWR article “Outbreaks of Escherichia coli O157:H7 Associated with Petting Zoos --- North Carolina, Florida, and Arizona, 2004 and 2005”.(Link below)

https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5450a1.htm

The section towards the end of the article entitled “Editorial Note” contains useful background information, as well as pointing out the implications of the investigations’ findings, and the further steps taken in North Carolina to prevent future outbreaks associated with petting zoos.

Questions

(1)  In the North Carolina outbreak, why was it significant that no specific food, beverage, or recreational water exposure was associated with illness?

(2)  What do you think was the hypothesis that was investigated in the case-control study performed on the North Carolina outbreak?

(3)  What sources of infection were implicated in the Arizona outbreak?

(4)  In each of the three outbreaks, data were reported on the occurrence of specific “pulsed-field gel electrophoresis” (PFGE) patterns. What is the significance of finding matching PFGE patterns when comparing different isolates of a pathogen?

Explanation / Answer

1.

The E.coli O157:H7 strain is associated with the outbreak in North Carolina. This has been found that dairy cattle and beef are the main reservoirs of this strain and also of the non O137 shiga toxin producing strains of the E.coli. This is the reason that no specific food, beverage, and recreational water exposure was associated with the illness. Also, specific food and beverages helped in overcoming the outbreak.

3.

Source of infection in the Arizona outbreak was the petting zoo animals that were the reservoir of E.coli O157:H7 strain. This has been that children with direct contact with petting zoo animal were affected with the diaarhea.

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.