Introduction

Herpesviruses can be found in primates throughout the animal kingdom. In the animal kingdom, the order of primates is classified into two suborders, the Prosimians and the Anthropoids (Fig. 61.1(a)). Prosimians are the earliest and most primitive of primates and are comprised of lemurs, lorises and tarsiers. Tarsiers share characteristics that are intermediate between the prosimians and the anthropoids, and hence are sometimes considered a third suborder. The Anthropoids are classified into platyrrhines (flat nosed) and catarrhines (downward pointing nose).

The platyrrhines are New World monkeys found exclusively in Mexico and Central and South America. This group includes tamarins, common marmosets, squirrel monkeys and spider monkeys. Evolution of the platyrrhines has been a subject of intense debate. Most believe that the origin and early diversification of platyrrhines occurred on the African continent. It is thought that the platyrrhines then crossed the Atlantic Ocean to the Americas at a time when sea levels were lower and the ocean ridges in the Atlantic were likely exposed as islands, creating pathways that were conducive to platyrrhine migration.

The catarrhines are sub-divided into Cercopithecoids or Old World monkeys (with tails) and Hominids (no tails) (Fig. 61.1(b)). Old World monkeys are found in both Africa and Asia. The rhesus monkey (Macaca mulatta) and the cynomolgus monkey (Macaca fascicularis) are examples of Old World primates found in Asia, while African green monkeys and baboons are Old World primates found exclusively in Africa. The Hominids include apes like chimpanzees, gibbons, gorillas, orangutans, and humans.