Division of Outbreak Investigation

In Maryland, healthcare providers, healthcare institutions, medical laboratories, teachers at schools, child care providers, masters of vessel or aircraft, owners or operators of a food service establishment are required to immediately report outbreaks of infectious diseases to their local health department under Code of Maryland Regulations (COMAR) and Maryland Code Annotated, Health-General (H-G) §§ 18-201, 18-202, and 18-205.

The Division of Outbreak Investigation provides support for local health departments in outbreak investigations by coordinating clinical and environmental specimen testing at the Laboratories Administration, Maryland Department of Health and Mental Hygiene (DHMH); and managing statewide outbreak related data. DHMH also works closely with the Centers for Disease Control and Prevention (CDC), the Maryland Department of Agriculture, the Food and Drug Administration (FDA) and the US Department of Agriculture (USDA) for support and collaboration on multistate investigations.

Outbreaks are reportable to DHMH within one working day after a local health department receives a report (COMAR The information provided at time of report includes:

  • Location/setting of outbreak
  • Number of ill cases and susceptible cases
  • Date the outbreak reported to local and state health
  • Infectious disease etiology suspected
  • Contact information

The goals of outbreak investigation and management in Maryland are to:

  • Decrease the number of outbreaks by improving outbreak response and prevention
  • Identify specific areas of improvement for outbreak investigation and reporting
  • Collate data on all reported outbreaks in a centralized and standardized manner

What is an Outbreak?

An outbreak is defined as an increase in cases of disease in time or place that is greater than expected. If a condition is rare (e.g. measles) or has serious public health implications (e.g. bioterrorism agent), an outbreak may involve only one case. When two or more cases in the same outbreak have a laboratory result involving the same etiologic agent, the outbreak is considered to be laboratory confirmed.

Local and state epidemiologists are responsible for outbreak investigations involving Maryland residents regardless of where they were exposed. Outbreaks involving residents from multiple states are usually coordinated by CDC. Investigations into the source of an outbreak can depend on the etiology involved (viral, bacterial, parasitic or chemical), the mode of transmission (foodborne, waterborne, environmental, person-to-person), or the outbreak setting (restaurant, hospital or assisted living facility, school or community).

Outbreak Data and Statistics

These are descriptive reports of the local outbreaks reported to the local health departments and subsequently to the state health department. These reports do not include multi-state outbreaks in which Maryland may have had cases.