An automated method for evaluating an infection status associated with a blood sample obtained from an individual, the infection status being a sepsis status, the method comprising: determining, using a first module, a cell count or concentration associated with the blood sample, wherein the cell count or concentration comprises a white blood cell count; determining, using a second module, a monocyte volume measure associated with the blood sample, wherein the monocyte volume measure is a standard deviation of monocyte volume associated with the blood sample; and evaluating, using a data processing module, the infection status associated with the blood sample; wherein the data processing module comprises a processor and a tangible non-transitory computer readable medium, and the computer readable medium is programmed with a computer application that, when executed by the processor, causes the processor to calculate a parameter using a function comprising the cell count or concentration and the monocyte volume measure, wherein the function comprises exp c − a × SDVMo − b × WBC 1 + exp c − a × SDVMo − b × WBC where: SDVMo is a standard deviation of monocyte volume, WBC is the white blood cell count, and a, b, and c are real number constants and to evaluate the infection status associated with the blood sample based on the parameter; wherein evaluating the infection status associated with the blood sample comprises comparing the parameter to a cutoff, wherein the cutoff is calculated by maximizing an estimated value of sensitivity for an infection for a value of specificity for an infection, and wherein the cutoff is 0.91 or greater; further comprising evaluating that an infection is not present in the blood sample when the parameter is less than the cutoff, and evaluating that an infection is present in the blood sample when the parameter is greater than or equal to the cutoff. determining, using a first module, a cell count or concentration associated with the blood sample, wherein the cell count or concentration comprises a white blood cell count; determining, using a second module, a monocyte volume measure associated with the blood sample, wherein the monocyte volume measure is a standard deviation of monocyte volume associated with the blood sample; and evaluating, using a data processing module, the infection status associated with the blood sample; wherein the data processing module comprises a processor and a tangible non-transitory computer readable medium, and the computer readable medium is programmed with a computer application that, when executed by the processor, causes the processor to calculate a parameter using a function comprising the cell count or concentration and the monocyte volume measure, wherein the function comprises exp c − a × SDVMo − b × WBC 1 + exp c − a × SDVMo − b × WBC where: SDVMo is a standard deviation of monocyte volume, WBC is the white blood cell count, and a, b, and c are real number constants and to evaluate the infection status associated with the blood sample based on the parameter; wherein evaluating the infection status associated with the blood sample comprises comparing the parameter to a cutoff, wherein the cutoff is calculated by maximizing an estimated value of sensitivity for an infection for a value of specificity for an infection, and wherein the cutoff is 0.91 or greater; further comprising evaluating that an infection is not present in the blood sample when the parameter is less than the cutoff, and evaluating that an infection is present in the blood sample when the parameter is greater than or equal to the cutoff. SDVMo is a standard deviation of monocyte volume, WBC is the white blood cell count, and a, b, and c are real number constants and to evaluate the infection status associated with the blood sample based on the parameter; wherein evaluating the infection status associated with the blood sample comprises comparing the parameter to a cutoff, wherein the cutoff is calculated by maximizing an estimated value of sensitivity for an infection for a value of specificity for an infection, and wherein the cutoff is 0.91 or greater; further comprising evaluating that an infection is not present in the blood sample when the parameter is less than the cutoff, and evaluating that an infection is present in the blood sample when the parameter is greater than or equal to the cutoff.