Managerial Epidemiology: Hepatitis Outbreak in the Midwest

Would You Call This an Epidemic or An Outbreak?

The situation described in the case study can be classified as an outbreak. An outbreak is a relatively small-scale occurrence of a disease in a well-defined community at numbers greater than expected for the area. The numbers of individuals affected by Hepatitis A are not large enough and are not followed up by similar diseases to constitute an epidemic. Many epidemics start as outbreaks, however.

What are the Steps in an Outbreak Investigation?

The general investigation plan for an outbreak or an epidemic consists of 10 steps, which are as follows (Fleming, 2015):

  • Identifying the problem;
  • Confirmation of the diagnosis;
  • Definitions and cases. The definition is based on the identified diagnosis and is used to count the number of afflicted individuals within an area;
  • Field word preparations;
  • Descriptive epidemiology of the incident;
  • Development and evaluation of hypotheses;
  • Consideration and refinement of hypotheses based on field data;
  • Implementation of additional studies;
  • Control and prevention actions;
  • Analysis of the aftermath.

Depending on the situation, some of these steps may be given more attention than others. Nevertheless, all of the steps mentioned above are present during an outbreak investigation.

Hepatitis A Is a Viral Pathogen. What are the Broad Categories of Diseases that One Must Consider When Investigating a Gastrointestinal Disease Outbreak?

The two broad categories to be considered during the investigation of a gastrointestinal disease outbreak are infections and intoxications (Kimberlin, Brady, Jackson, & Long, 2015). The former is caused by various viruses, parasites, or bacteria invading the mucosa, the intestinal tract, or other tissues. It takes time for viruses or bacteria to reach a critical mass to start affecting the person, meaning long incubation times. Intoxications, on the other hand, are caused by toxins contaminating the food or water. These outbreaks are typically quick to discover, as the incubation period ranges from minutes to several hours at best.

What Characteristics Can be Used to Describe Infectious Agents?

The main characteristics used to describe infectious agents are infectivity, pathogenicity, and virulence (Fleming, 2015). Infectivity stands for the ability of the agent to transmit from one person to another. Although nearly all agents are labeled as infectious, the ability to communicate ranges from one disease to another. Pathogenicity stands for the ability of the agents to cause diseases in human beings and other living creatures, including animals, birds, plants, and others. Lastly, virulence is used to describe the severity of the affliction.

What Measures of Morbidity Would You Use to Estimate Infectivity, Pathogenicity, and Virulence?

There is a statistical method of estimating infectivity, pathogenicity, and virulence of a disease (Peery et al., 2015). Infectivity is calculated by dividing the numbers of a subject infected by the number of subjects exposed. The higher the number, the more infectious a disease is. Pathogenicity is determined by dividing the number of diseased patients by the number of infected patients. The higher the number, the more likely it is for the agent to result in disease. Lastly, virulence is determined by dividing the number of patients with serious symptoms (and death) by the number of total diseased patients. If a disease is likely to provoke a serious health issue, the virulence score will be high.

What are the Different Modes of Transmission? Describe the Possible Routes of Transmission.

Diseases are typically transmitted either directly or indirectly. Direct mode of transmission involves contact and fluid exchange between individuals, which typically results from sexual activity, kissing, in utero, or airborne sprays (Fleming, 2015). Indirect transmission has much more potential routes to affect individuals, such as human carriers, animal and insect carriers, or environmental carriers, which include food, water, air, and others.

How Would You Characterize Hepatitis A?

Hepatitis A can be classified as a disease that has the following parameters (Perkins et al., 2017):

  • Infectivity: Moderate, requires specific conditions;
  • Pathogenicity: High, once exposed to the agent, an individual is very likely to contract the disease;
  • Virulence: Low. The majority of individuals exposed to the disease have mild symptoms and make a full recovery within a week.
  • Possible routes of transmission: Food and water exposed to excrements of the infected.

References

Fleming, S. T. (Ed.). (2015). Managerial epidemiology: Cases and concepts (3rd ed.). Chicago, IL: Health Administration Press.

Kimberlin, D. W, Brady, M. T., Jackson, M. A., & Long, S. S. (Eds.). (2015). Red book: 2015 report of the committee on infectious diseases (30th ed.). Itasca, IL: American Academy of Pediatrics.

Peery, A. F., Crockett, S. D., Barritt, A. S., Dellon, E. S., Eluri, S., Gangarosa, L. M., … Sandler, R. S. (2015). Burden of gastrointestinal, liver, and pancreatic diseases in the United States. Gastroenterology, 149(7), 1731-1741.

Perkins, M. D., Dye, C., Balasegaram, M., Brechot, C., Mombouli, J.-V., Rottingen, J.-A., … Boehme, C. C. (2017). Diagnostic preparedness for infectious disease outbreaks. The Lancet, 390(10108), 2211-2214.