Define and classify host. Define infection and infestation.

Q. 39. Define and classify host. Define infection and infestation. 
 Classification of host:- 
1. Obligate host :- It means the only host e, g, man in measles and typhoid fever. 
2. Definitive host :- Hosts in which the parasite attains maturity or passes its sexual stage are called primary or definitive hosts. 
3. Intermediate host :- Hosts in which the parasite is in a larval or asexual state are called secondary or intermediate host. 
4. Transport host :- It is a carrier in which the organism remains alive but does not undergo development. 
 Infections :- Infection is the entry and multiplication of an infectious agent in a host. 
 Infestation :- The term infestation means the ladge. ment development and reproduction 
of arthropods on the surface of the body or in the clothings or invasion of the gut by 
helminthes.