Event and Case Definition

One Health Harmful Algal Bloom System (OHHABS) – Harmful Algal Bloom (HAB) Event and Case Definitions

Table 1. Definition of a HAB event
Definition
HAB Event

Criteria
Laboratory-based HAB data¹

Observational or environmental data²

Required to have 1

1. Suspect
2. Confirmed

Associated illness

Required

3. Confirmed

Required

Required

¹ Laboratory detection (e.g., microscopic confirmation or DNA analyses) of cyanobacteria, other potentially toxin-producing algae, or algal/cyanobacterial
toxins in a water body or finished drinking water supply
² Observational (e.g., scum, algae, water color change, sheen, photographic evidence, satellite data) or environmental (e.g., pH, chlorophyll, nutrient
levels) data from a water body to support the presence of an algal bloom
Blue shaded cells: you must have at least one of the criteria described in the shaded cell.

Updated 03/14/2017

1

Table 2. Definition of a Human HAB-associated case
Definition
Exposure¹

Signs/
symptoms²

1. Suspect

Required

Required

Required

2. Probable

Required

Required

Required

3. Probable

Required

Required

Required

4. Confirmed

Required

Required

Required

5. Confirmed

Required

Required

Required

Human HABassociated Case

Criteria

Public
Professional Other causes
health
medical
of illness
assessment³ diagnosis4
ruled out

Observational
or
environmental
data5

Laboratorybased HAB data6

Clinical
data7

Required to have 1
Required

+/-

Required to have 1
Required

Required

+/-

+/-

+/-

+/-

Required

Required

¹ Exposure (i.e. physical contact, inhalation, ingestion) to water, algae, or seafood, dietary supplements
² Self-reported signs/symptoms after exposure
³ Public health assessment is defined as the action of compiling all data available and deciding that the illness in question is likely HAB-related
4
Professional medical diagnosis being provided by a medical practitioner (e.g., doctor, nurse, physician assistant) based on his or her medical assessment
of the patient’s symptoms, medical history, exposure, etc.
5
Observational (e.g., scum, algae, water color change, sheen, photographic evidence, satellite data) or environmental (e.g., pH, chlorophyll, nutrient levels)
data from a water body to supporting the presence of an algal bloom
6
Laboratory detection of cyanobacteria or other potentially toxin-producing algae, (e.g., microscopic confirmation or DNA analyses) or
algal/cyanobacterial toxins (e.g., bioassay, HPLC) in a water body, finished drinking water supply, seafood or dietary supplements
7
Laboratory documentation of cyanobacteria, other potentially toxin-producing algae, or algal/cyanobacterial toxins in a clinical specimen
Blue shaded cells: you must have at least one of the criteria described in the shaded cell.
+/-: indicates that this criteria is optional and while it strengthens the case, but it does not change case classification (e.g., suspect to probable, probable to confirmed).

Pink shaded cells: you must have this criteria described in the shaded cell.

Updated 03/14/2017

2

Table 3. Definition of an Animal HAB-associated case
Definition
Exposure¹

Signs²

Animal HABassociated Case

Public
health
assessment³

1. Suspect

Required

Required

Required

2. Probable

Required

Required

Required

3. Probable

Required

Required

Required

4. Confirmed

Required

Required

Required

5. Confirmed

Required

Required

Required

Criteria
Professional Other causes
medical
of illness
diagnosis4
ruled out

Observational Laboratory-based
or
HAB data6
environmental
data5

Clinical
data7

Required to have 1
Required

+/-

Required to have 1
Required

Required

+/-

+/-

+/-

+/-

Required

Required

¹ Exposure (i.e. physical contact, inhalation, ingestion) to water, algae or other dietary HAB sources. This includes undocumented exposures that are
suspected based on temporal or spatial factors (e.g.,, proximity of carcass to a body of water that is experiencing a bloom) or an animal’s opportunity for
exposure due to biological, behavioral, or other relevant factors (e.g., natural habitat of the animal is near or in the body of water, penned livestock’s only
source of drinking water, etc.).
² Reported signs after exposure, including the outcome of death prior to discovery.
³ Public health assessment is defined as the action of compiling all data available and deciding that the illness in question is likely HAB-related.
Assessments may also be completed by qualified non-public health entities (e.g., fish and wildlife staff, university researchers) that have been identified by
State or Federal agency partners.
4
Professional medical diagnosis being provided by a medical practitioner (e.g., veterinarian) based on his or her medical assessment of the animal(s)’s
signs, medical history, likelihood of exposure, etc.
5
Observational (e.g., scum, algae, water color change, sheen, photographic evidence, satellite data) or environmental (e.g., pH, chlorophyll, nutrient levels)
data from a water body to identify an algal bloom
6
Laboratory detection of cyanobacteria or other potentially toxin-producing algae, (e.g., microscopic confirmation or DNA analyses) or
algal/cyanobacterial toxins (e.g., bioassay, HPLC) in a water body, finished drinking water supply, seafood or animal dietary sources
7
Laboratory documentation of cyanobacteria, other potentially toxin-producing algae, or algal/cyanobacterial toxins in a clinical specimen.
Blue shaded cells: you must have at least one of the criteria described in the shaded cell
+/-: indicates that this criteria is optional and while it strengthens the case, but it does not change case classification (e.g., suspect to probable, probable to confirmed).

Pink shaded cells: you must have this criteria described in the shaded cell.

Updated 03/14/2017

3