Why has vaccination failed to eradicate cholera?
1 )
The pathogen exists in many strains which mutate.
The pathogen is present in the lumen of the gut.
3 )
The pathogen is waterborne.
4 )
There is a stage of the life cycle in other mammals.
تحلیل ویدئویی تست
تحلیل ویدئویی برای این تست ثبت نشده است!