<prompt> Cyclic trend is shown by-Measles epidemicInfluenza pandemicRubella epidemicAll of the above  <response>: Ans. is d i.e., All of the above Cyclic trend Some diseases occur in cyclic spread over a short period of time which may be week, days, months or years. This is due to naturally occuring variation in herd immunity. A build up of susceptible is again required in the herd before there can be another attack. It may be due to antigenic variations as occur in influenza. Examples - Epidemic of Measles - every 2-3 years Rubella - every 6-9 years Pandemic of influenza - every 10-15 years. 