A suspected case: Reported head nodding in a previously normal person; head nodding was defined as repetitive, involuntary drops of the head to the chest on two or more occasions. This case definition is used at the community level.
A probable case is a suspected case with: Both of the following major criteria:
-Age at onset of nodding between 3 and 18 years old
-Frequency of nodding 5 to 20 per minute
Plus at least one of the following minor criteria:
-Other neurological abnormalities (cognitive decline, school dropout due to cognitive/behavioural problems, other seizures or neurological abnormalities)
-Clustering in space or time with similar cases
-Triggered by food and/or cold weather
-Stunting or wasting
-Delayed sexual or physical development
-Psychiatric symptoms
A confirmed case is a probable case plus a documented nodding episode that is: Observed by a trained healthcare worker or recorded on film or on EEG/EMG.