What are the recommended measures for preventing internal parasites in alpacas and llamas?

A good feeding is important to reduce the susceptibility of animals to diseases.
Dividing the herd into categories according to their nutritional requirements is recommended.
Hygiene of the sleeping areas is important to prevent the transmission of diseases.
Avoiding contact with sick animals is important to prevent the spread of diseases.
Treating animals with anti-parasitic products is the only measure needed to control internal parasites.