There are so many parasites around the wrorld but each continent has a more predominant parasite.
For the 7 continents, the most common parasites are as follows:
North America: Protozoa/ Roundworm
Asia: liver Fluke (Fasicola hepatica)
South America: Chagas Disease (Trypanosoma cruzi)
Australia: Tapeworm
Antarctica: Cestode
Africa: Malaria (Plasmodium)
Europe: Leishmaniasis (Phlebotomous sand fly)
A list of common infectious diseases in these continents are as follows:
Africa: Cholera
North America: Chicken pox (Varicella)
South America: Chagas Disease
Europe: Hepatitis B
Asia: Dengue
Australia: Avian Flu
Antarctica: Common Cold

PET PARASITE
One of the most common pet parasites are Ticks. They spread lyme disease, which is very disabling if not treated early enough. Ticks carry a number of different pathogens which can cause so many other diseases in addition to lyme disease. The image below shows the life cycle of the tick and how it depends on the infection process to continue its life cycle.
 The second image shows the distribution of reported lyme disease cases in the US in 2008.

HUMAN INFECTIOUS DISEASE
One of the most common human infectious diseases is chicken pox, also known as varicella. It is a virus that infects a large number of children every year and even though vaccines have been developed, numerous people still continue to contract the disease.  The pictures below show the distribution of chicken pox in the US and the life cycle of the infectious agent.