Answer
The first graph shows a seasonal pattern, with case reports tending to increase in winter and spring. Very few cases of the historically dominant grey strain have been reported in the last 5 years and in recent months, the total number of case reports (in blue) well exceeds the combined tally for the two historically dominant strains. The second graph shows that although there are variations, both genders are affected roughly equally, but by age group, children under 5 years are disproportionately affected, as are young adults and the elderly.
The disease is meningococcal disease. Cases due to meningococcal serogroup C (in grey in the top graph) have largely disappeared thanks to high vaccination rates, and serogroup B (in red in the top graph) is the dominant strain. In recent months, there has been an upward trend in notifications of cases due to serogroup W bacterial infection (not shown in the top graph).
For more information, see Meningococcal disease.
