Table 2.

Derivation of multipliers to estimate the incidence of brucellosis in the Moshi Rural and Moshi Urban Districts, Kilimanjaro Region, Tanzania

	Multiplier equation	Multiplier for period
		2007–2008		2012–2014
KCMC multiplier	=no. of households interviewed/no. of households seeking care at KCMC for fever ≥3 days
age <5 years		198/17	11.63	198/17	11.63
age 5–14 years		361/10	36.10	361/10	36.10
age ≥15 years		810/35	23.10	810/35	23.10
MRRH multiplier	=no. of households interviewed/no. of households seeking care at MRRH for fever ≥3 days
age <5 years		198/67	3.00	198/67	3.00
age 5–14 years		361/137	2.64	361/137	2.64
age ≥15 years		810/299	2.71	810/299	2.71
Referral adjustment multiplier	=no. of study patients admitted to KCMC without referral from another facility/no. of patients admitted to KCMC
age <5 years		166/249	0.67	N/A	N/A
age 5–14 years		40/55	0.80	N/A	N/A
age ≥15 years		72/94	0.77	N/A	N/A
Enrolment multiplier	=no. of eligible patients/no. of patients enrolled in fever surveillance	1310/870	1.51	2394/1420	1.69
Blood drawn multiplier	=no. of patients included in the incidence study/no. of patients for whom serology was performed
age <5 years		249/232	1.07	409/335	1.22
age 5–14 years		58/57	1.02	110/108	1.02
age ≥15 years		278/274	1.01	576/554	1.04
Study duration multiplier	=no. of months per year/study duration (in months)	N/Aa	N/A	12/27	0.44
Time multiplier	=no. of days in a week/no. of enrolment days per week	7/5	1.40	7/5	1.40
Paired sera multiplier	=no. of patients included in the incidence study for whom serum was collected/no. of patients included in the incidence study with paired sera	563/314	1.79	997/632	1.58
AT specificity multiplier	=specificity	0.96	0.96	0.96	0.96

AT: agglutination test; N/A: not applicable.

^aStudy duration multiplier not applicable for 2007–2008 study period because the study enrolment lasted 1 year and 15 days, therefore it was not necessary to annualize the case numbers.