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EGERTON UNIVERSITY
COLLEGE OF OPEN AND DISTANCE LEARNING
E-CAMPUS
ZOOL 143: Biology of HIV/AIDS and Society
Topic 1 Handout
Copyright
Copyright© Egerton University
Published 2020
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system or transmitted in any form or by any means, electronic, mechanical,
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copyright owner.
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Topic One: Introduction To Hiv And Aids
Introduction
HIV/AIDS is a global pandemic and national disaster. HIV attacks the human
body and gradually weakens the immunity, the ability of the body to defend itself
against diseases. Have you ever heard of HIV/AIDS? Do you know of anyone
infected and/or affected by this disease? What are some of the challenges caused
by HIV/AIDS? Do you understand the difference between HIV and AIDS? Which
one comes earlier, HIV or AIDS? Is knowledge a vital weapon in the fight against
HIV/AIDS? These are some of the questions that we focus in this introductory
topic. We take you through the definition of the terms (HIV and AIDS), examine
the link between the two and the challenge posed by the pandemic. Welcome.
Learning Outcomes
By the end of this topic you should be able to:
i. Differentiate between HIV and AIDS,
ii. Explain the challenges posed by the pandemic
iii. Explain the significance of knowledge in the fight against the pandemic.
iv. Describe the history and origin of HIV.
1.0 Definition of Terms
HIV
HIV stands for Human Immunodeficiency Virus.
This particular virus was discovered in the mid-1980s and belongs to a group of
viruses called retroviruses.
HIV attacks the immune system, and gradually causes damage. This can mean that
a person infected with HIV is at risk of developing some serious infections and
cancers that a healthy immune system can fight off. When a person develops
certain illnesses and cancers, they are said to have developed AIDS.
AIDS
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AIDS stands for Acquired Immune Deficiency Syndrome. AIDS is the name used
to describe a combination of potentially life-threatening infections and cancers,
which can develop when someone’s immune system has been damaged by HIV.
Prevalence
Prevalence is the number of people living with HIV infection at the end of a given
year.
Incidence
Incidence is the number of new HIV infections that occur during a given year.
Link btw HIV & AIDS
-AIDS is the name used to describe a combination of potentially life-threatening
infections and cancers that can develop in people who have HIV.
-Over time, infection with HIV damages the immune system. This means that the
body cannot fight off a number of serious infections and cancers, which are
sometimes called ‘AIDS-defining’.
-Just because you are diagnosed with an AIDS-defining illness doesn’t mean that
you are going to die. Many of these illnesses can be cured or managed.
The Challenge
-In 2009, 1.8 million people died from HIV/AIDS and another 2.6 million people
were infected with the virus. Sub-Saharan Africa has been hit harder by
HIV/AIDS than any other region in the world. Two-thirds of people living with
HIV/AIDS and three-quarters of deaths from HIV/AIDS are in sub-Saharan
Africa.
-People with AIDS don’t suffer alone. The disease also attacks their families and
communities. 14.8 million African children have already lost one or both parents
to HIV/AIDS.
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-The disease targets people during their most productive years, making economic
progress in many sub-Saharan African countries even more of a challenge.
-Unfortunately, HIV/AIDS has neither a cure nor vaccine at present. Until a
vaccine or a cure is found, our greatest weapon against HIV/AIDS is knowledge.
Importance of Learning about HIV/AIDS
➢ Learning about HIV/AIDS can empower people to make decisions that can
minimize the risk of exposure to HIV/AIDS and help prevent its spread.
➢ Education is the first of self-protection, community improvement, and
empowerment.
➢ The information in this book is also designed to help those individuals
already living with HIV/AIDS in the world today.
➢ It is a resource for everyone to learn how to support friends, family
members, and community members who have HIV/AIDS.
1.2 History of HIV/AIDS
AIDS has been around for at least several decades. It is estimated to first have
infected humans in the 1910’s and 1920’s. The virus spread to humans from
primates, as is the case for many diseases. These types of diseases are called
zoonoses (the singular form is “zoonosis”). Hunting, eating, and domesticating
animals can all create situations where microbes have the opportunity to exchange
animal hosts for humans. Humans have been infected by zoonoses for thousands
of years. HIV and SARS are some recent examples. HIV-1 probably originated in
chimpanzees, which then transferred it to humans.HIV-2, a separate virus that can
also cause AIDS, originated in another primate-the sooty monkey.
1981 to 1991
In 1981, scientists first identified AIDS. This happened in the United States,
where researchers observed a sudden surge in opportunistic diseases in patients
with no prior history of immune system problems. Opportunistic diseases are
diseases that do not cause major problems in healthy individuals, but flourish in
the absence of a functional immune system. One example of an opportunistic
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disease is Pneumocystis carinii (PCP) Pneumonia. When the researchers further
examined the patients suffering from these infections, they found that indeed their
immune systems were damaged. Some new, hitherto unknown disease had to be at
work.
The new disease was given the name Acquired Immunodeficiency Syndrome. By
studying the patterns of this new disease, doctors and epidemiologists came to the
conclusion that it was probably caused by a virus. In 1982, the Human
Immunodeficiency Virus (HIV) was identified as the cause of the disease, and two
years later it was isolated by French and American researchers.
In the United States around the time of the discovery, the major afflicted group in
the population was male homosexuals. Another group in which HIV was prevalent
was intravenous drug users. Heterosexual non drug-users were also infected, but
were not focused on by researchers. In 1983, the scientific community in western
countries was first confronted with evidence for an epidemic in Africa that
afflicted mostly homosexuals. This led to the realization that this new disease had
the capability of affecting everyone, but just some sub groups in the population.
By 1985, at least one case of AIDS had been reported in every region of the
world. In the years shortly afterwards, the growth of HIV/AIDS awareness on a
global scale could be observed. For example, the world Health Organization
started it Special Program on AIDS. Also, in 1987 the first AIDS therapy, AZT,
was introduced in the United States.
1991 to Present
During this period, the epidemic surges. After the first decade of the pandemic,
roughly 15 million people were living with the disease. (This is a measure of
prevalence, or total number of people infected. Another way of tracking a disease
is to look at incidence, which is the number of new cases within a given period of
time.). The first success in reducing rates in a developing country was observed in
Uganda in 1993. Prevalence in young pregnant women began to decrease. In
recent years, Thailand and Brazil have brought down their rates. Globally,
however, the number of infected people keeps rising.
In 1993, scientists develop the first regime to prevent mother-to-child
transmission. Two years later, Highly Active Antiretroviral Therapy (HAART)
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is introduced. (See chapter on Treatment). In that same year, UNAIDS, a body of
the United Nations specifically dealing with the AIDS epidemic, was created.
In 2001, twenty years after scientists first identified HIV, some 337 million people
were living with HIV/AIDS. Now this figure is even higher-42 million is the most
recent estimate. More and more therapies are being developed, but none of them
can cure the disease. Moreover, many of them are only available to a very small
percentage of infected individuals because of their high costs. The epidemic is far
from over.
1.3 Origin of HIV
a. The natural transfer theory (The hunter Theory)
-States that HIV began to infect humans after it was transferred from an infected
primate to a human. This transfer likely occurred when hunters came into contact
with infected blood of an infected primate through scratches, bites, and cutting the
animal for meat.
-It’s based on the genetic similarity between HIV and SIV (Simian
Immunodeficiency Virus).
b. The oral polio vaccine (OPV) theory
It suggests that HIV can be traced to the testing of an oral polio vaccine called
Chat, given to about a million people in the Belgian Congo, Ruanda and Burundi
in the late 1950s. To be reproduced, live polio vaccine needs to be cultivated in
living tissue, and Hooper’s belief is that Chat was grown in kidney cells taken
from local chimps infected with SIVcmz. This, he claims, would have resulted in
the contamination of the vaccine with chimp SIV, and a large number of people
subsequently becoming infected with HIV-1.
Many people have contested Hooper’s theories and insist that local chimps were
not infected with a strain of SIVcmz that is closely linked to HIV. Furthermore,
the oral administration of the vaccine would seem insufficient to cause infection in
most people (SIV/HIV needs to get directly into the bloodstream to cause
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infection – the lining of the mouth and throat generally act as good carriers to the
virus).
In February 2000 the Wistar Institute in Philadelphia (one of the original
manufacturers of the Chat vaccine) announced that it had discovered in its stores a
phial of polio vaccine that had been used as part of the program. The vaccine was
subsequently analyzed and in April 2001 it was announced that no trace had been
found of either HIV or chimpanzee SIV.7 A second analysis confirmed that only
macaque monkey kidney cells, which cannot be infected with SIV or HIV, were
used to make Chat.8 While this is just one phial of many, it means that the OPV
theory remains unproven.
c. The conspiracy Theory (HIV as man-made Product)
-It states that HIV was manufactured in the laboratory as part of a biological
warfare program, designed to wipe out large numbers of black and homosexual
people.
-This theory has been disapproved on the grounds that there were no genetic
engineering techniques at that time of emergence of AIDS.
d. The colonialism theory
During the late 19th and early 20th century, much of Africa was ruled by colonial
forces. In areas such as French Equatorial Africa and the Belgian Congo, colonial
rule was particularly harsh and many Africans were forced into labour camps
where sanitation was poor, food was scarce and physical demands were extreme.
These factors alone would have been sufficient to create poor health in anyone, so
SIV could easily have infiltrated the labour force and taken advantage of their
weakened immune systems to become HIV. A stray and perhaps sick chimpanzee
with SIV would have made a welcome extra source of food for the workers.
“SIV could easily have infiltrated the labour force and taken advantage of their
weakened immune systems”
e. The contaminated needle theory
In the 1950s, the use of disposable plastic syringes became commonplace around
the world as a cheap, sterile way to administer medicines.
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However, to African healthcare professionals working on inoculation and other
medical programmes, the huge quantities of syringes needed would have been
very costly. It is therefore likely that one single syringe would have been used to
inject multiple patients without any sterilization in between.
This would rapidly have transferred any viral particles (within a hunter’s blood for
example) from one person to another, creating huge potential for the virus to
mutate and replicate in each new individual it entered, even if the SIV within the
original person infected had not yet converted to HIV.
Topic Summary
• In this topic, we have learned that HIV is virus that weakens human
immunity.
• AIDS is a word that describes a combination of potentially life-threatening
infections and cancers, which can develop when someone’s immune system
has been damaged by HIV.
• HIV/AIDS was discovered in 1981 and its origin can be traced from
primates, the Oral polio vaccine, conspiracy theory, colonialism and the
contaminated needle theory.
Further Reading
• Talaro KP, 2007. Foundations in Microbiology, Basic Principles. 6th
edition. McGraw-Hill International.
• William L, Anderson WL, Janeway C and Travers P. 2001.
Immunology, The immune System in Health and Disease. 5th edition,
Garland Publishing, Inc.
