Table 4.

The number of animals by sex, species and age recruited for the longitudinal study and their respective estimates of animal time at risk (months), number of observed cases and Brucella infection incidence rate

Variable	Levels	n	Animal-time	Cases	Incidence rate
					Estimate	95% Confidence interval
Sex	Male	8	61.60	1	0.016	0.0004–0.091
	Female	71	549.40	11	0.020	0.009–0.036
Species	Cattle	31	214.03	6	0.028	0.010–0.061
	Camels	30	151.00	8	0.053	0.022–0.104
	Goats	32	237.40	3	0.013	0.003–0.036
	Sheep	22	161.00	1	0.006	0.0002–0.034
Age	Young	11	74.30	2	0.026	0.003–0.097
	Adult	62	536.7	10	0.019	0.009–0.034