Final answer:
The two main types of Human Immunodeficiency Virus, HIV-1 and HIV-2, likely jumped to humans through direct contact with infected primates. HIV-1 is now a global pandemic, and sub-Saharan Africa has the highest prevalence. Transmission can occur through sexual contact, infected bodily fluids, and from mother to child.
Step-by-step explanation:
The Human Immunodeficiency Virus (HIV) is responsible for causing Acquired Immunodeficiency Syndrome (AIDS). Scientists have identified two types of HIV—HIV-1 and HIV-2. HIV-1 is prevalent worldwide, while HIV-2 is mainly found in West Africa. The viruses are believed to have jumped to humans from primates in Central Africa, a process known as zoonotic transfer. The transfer likely happened when humans hunted, butchered, and consumed the meat of these animals. This type of zoonotic spillover is not uncommon; it is also seen with other diseases like SARS and avian influenza, which have transmitted from animals to humans through similar means of close interaction.
Most researchers believe that HIV originated in sub-Saharan Africa during the 20th century. HIV transmission occurs through sexual contact, contact with infected bodily fluids, and from mother to child during childbirth or breastfeeding. This virus has become a global pandemic, significantly impacting regions such as sub-Saharan Africa, where access to treatment is limited.