Table 3.

Calculations for estimated average annual burden of malaria epidemics in Africa expressed as total number of clinical malaria episodes, severe cases and deaths, and derived using two alternative PAR estimates^a

	A. Using assumed attack rate		B. Using documented attack rate
	PAR estimate from WHO	PAR estimate from Snow et al.	PAR estimate from WHO	PAR estimate from Snow et al.
Scenario 1
Average annual number of malaria episodes	13,190,503	7,614,310	7,650,492	1,921,851
Average annual number of severe cases	659,525	380,715	382,525	96,093
Average annual number of deaths (range)	164,881–329,763	95,179–190,358	95,631–191,262	24,023–48,046
Scenario 2 b
Average annual number of malaria episodes	10,792,230	6,229,890	6,259,493	1,572,424
Average annual number of severe cases	485,650	280,345	281,677	70,759
Average annual number of deaths (range)	109,271–218,543	63,078–126,155	63,377–126,755	15,921–31,842
Scenario 3 c
Average annual number of malaria episodes	15,247,000	9,306,379	9,350,601	2,348,929
Average annual number of severe cases	838,585	511,851	514,283	129,191
Average annual number of deaths (range)	230,611–461,222	140,759–281,518	141,428– 282,856	35,528– 71,055

^aCalculations are repeated using (A) the assumed average annual attack used by Worrall et al. [5], and (B) the median average annual attack rate reported in this review. Scenario 1 uses similar assumptions to those used by WHO for its own burden calculations. These assumptions have been altered in Scenarios 2 and 3 to reflect more ‘optimistic’ and ‘pessimistic’ situations by altering only the frequency of epidemics and the clinical attack rate associated with them.

^bScenario 2 incorporates a 10% decrease in epidemic frequency and clinical attack rate over scenario 1

^cScenario 3 incorporates a 10% increase in epidemic frequency and clinical attack rate over scenario 1