The life or death of the host is no concern to the parasite. A parasite concern is 1. To find a host 2. Use the host for energy 3. Reproduce 4. Leave the old host and enter a new host for their perpetuation This happens in most of the cases like in TB, malaria, Typhoid, Cholera, African sleeping sickness, Ascariasis, Amoebiasis etc. But there are some parasites which don't kill host and the host doesn't have any effect of the parasites. Such a host is called Reservoir. The monkey is the reservoir for plasmodium vivax which cause malaria in humans. some parasites are useful and they live along with us as symboints.