UPDATED: 02/10/00 UPDATED: 02/10/00 
MICROBIOLOGY | CHEMISTRY | MEDICAL
Risk of STD for Women who are sexually active |
More Young, Gay Men Report Unsafe Sex; Highly Drug-Resistant Strains Of AIDS Virus Are On The Rise
Women and AIDS; Female Protection Against STD Infections; HIV in Semen
Incidence of New Syphilis Cases
A Vaccine Against HPV May Mean an End to Cervical Cancer 4/99
"It
(STD) is taken when one pocky person doth synne in lechery one with another" Author unknown. |
Sexually transmitted diseases or STDs present a unique Public Health problem. Before continuing I wish it to be CLEARLY UNDERSTOOD that I deal with the problem of STDs strictly as a medical and microbial issue and not as a moral, ethical or religious question. In spite of this disclaimer, there will be those who upon reading this material will take it that I am PREACHING MORALS to them. Let me assure you that the microbes involved are no more interested in our morals than we are the morals of the cow that contributed the meat of a hamburger we've enjoyed recently. The STD microbe's only desire (as is ours) is to survive and reproduce and to do so they will adapt their pathogenic behavior to FIT THE BEHAVIOR OF THEIR HUMAN HOSTS. Therefore, from a strictly evolutionary standpoint we humans have it within our power through our SOCIAL ATTITUDES AND BEHAVIOR, TO CONTROL these diseases; a power we lack over many other diseases. Morality aside it is a BIOLOGICAL FACT that changes in human behavior could ELIMINATE STDs as a serious disease problem.
All forms of life have a powerful INSTINCT to procreate, indeed it is the PRIME DIRECTIVE of all life, and I have presented the #genetic reason for sex being a required part of the process of reproduction. In the case of STDs, human reproductive drive (instinct?) combines with human intellect and social development to produce a complex situation and one that we humans haven't yet dealt with very successfully. The dilemma humans face are the facts that (1) STDs require sexual activity for their transmission; (2) humans require sexual activity to procreate and; (3) powerful reward systems are built in to the performance of the STD-transmission act (sexual intercourse). The STD microbes might best be viewed as DEADLY HITCHHIKERS on a natural process that our very survival requires and for which we are richly rewarded for undertaking.
The learning goals are:
To learn what sexually transmitted
diseases are.
To learn the characteristics and
epidemiology of some major STDs.
To learn, in detail the epidemiology
and disease characteristics of the HIV virus.
To learn how STDs may be dealt with
both medically and socially.
"Remember, hormones always win over neurons" Advice given to Dr. Karl Johnson by his father as he left home for college. From talk by Dr. Karl Johnson at WSU Nov. 6, 1995. |
STDs or sexually transmitted infections (STIs) are primarily transmitted through the exchange of body fluids containing the pathogen. The most common mechanism of transmission involves the intimate "sexual act" between two people involving close physical contact. The most common type of these activities is "sexual intercourse". STD-pathogens are usually transmitted through contaminated blood and/or semen. For this discussion a "sexual act" is defined as "any act whereby a sexual organ (or organs) comes into intimate contact with another person (usually an orifice) such that contaminated material (usually bodily fluid) exchange can occur". The portals of entry of STDs into hosts are:
In each case transmission occurs through, or is greatly assisted by, breaks (even microscopic ones) in the protective tissue (vaginal lining, penis, anal tissue, mouth tissue, skin); penetration through unbroken barriers is considered to be difficult if not impossible for most STD-pathogens.
| The Wisdom of the Body by Dr. Sherwin B. Nuland: "The ovum wants only one thing: not to die unfertilized. All of those passions and poems, all of those rages and roses, all of that sexiness and subtlety with which humankind has adorned the sweet prelude to fertilization, are in the service of the ovum's need. Empires fall, ids explode, great symphonies are written, and behind all of it is a single instinct that demands satisfaction--the ovum must have its way. So purposeful is the ovum in its quest that it figuratively contorts and drivers the mind of humanity in ways we have barely begun to understand. With disguises and subterfuges to entrap and allure, the little seductress makes the goal so desirable that it sometimes seems beyond attainment, and therefore more to be pursued." |
No discussion of the medical and epidemiological aspects of STDs is possible without considering the impact of OUR GENES AND OUR SOCIAL AND RELIGIOUS ATTITUDES. Our evolutionary history selected humans that were successful breeders. Genes which contributed to our enthusiastic procreation outlived those that didn't. We humans have trouble thinking rationally about anything having to do with sex. Sex pushes our buttons in numerous ways. Sex is highly emotional, it makes us uncomfortable, it embarrasses us, it titillates us, it treads on all sorts of taboos and provokes irrational and often mean-spirited responses from people. In this discussion the role of social and religious attitudes will be considered from the perspective of how they effect the EFFICACY OF TRANSMISSION of the STDs. Imposed upon this already horrendously complex problem are political issues, homophobia, myths, fears, guilt, economic considerations and malignant ignorance (= a positive effort to remain ignorant). I shall attempt to tread light through this emotional mine field, but please feel free to express your REASONED views and perspectives with me and the class either in class or via e-mail.
EXTRA
CREDIT COMMENTARY 16A: DLS: Luke Heath 1/12/00 My parents gave me some advice on the subject of sex. They said to wait until you get married. I will admit that this is not easy advice to follow in this day and age, but after reading several articles and this chapter, I agree that their advice is very sound. Abstinence, after some consideration, is really about protecting you and your signficant other from emotional setbacks (possibly for some people) and disease. HIV could be stopped if everyone in the world acceptted and practiced abstinence before marriage. This is however, very unlikely.
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Let us attempt to put aside our prejudices and negative baggage on this issue and try for a while to deal with it strictly as a MICROBIAL PROBLEM. Want to find out about your sex life? Visit this site.
This site contains graphic pictures of STDs that some will find disgusting: Click here to view pictures of STD infections. If these picture "turn-you-on" please seek help immediately!
The STD situation is a classical "good news/bad news"
situation. As you can see from viewing the latest 
CDC report on STDs in the US, the good news is that the
incidents of some STDs is declining, while the bad news is that others are on the
increase. You should be able to answer which STDs are decreasing and which are increasing.
Although AIDS has received the bulk of the attention in the past 10 years, while most other STDs have been ignored, the overall STD "problem" continues to grow at an alarming rate both in the US and world wide. There are numerous reasons suggested for this growth. Most lists of reasons for the increase include:
The flow of people from the countryside into the urban areas (e.g. Mexico City
now has ~20 million people) and the subsequent breakdown of cultural restraints.
The increased travel within and outside of national borders (truckers that
spread HIV across Africa).
The influence of movies, TV and other forms of communication that offer
individuals an unrealistic view of personal (& sanitary) behavior (e.g. smoking &
sex without consequences).
The attention a given STD receives is dependent upon three factors: (1) its lethality; (2) its cost; and (3) its publicity quotient. The latter refers to the attention a STD receives because of the nature and/or number of people infected; i.e., a sudden dramatic increase in the number of cases of a STD (e.g. genital herpes) or the report of a well-known figure (e.g. Magic Johnson, Rock Hudson) contracting or dying from a given STD attracts the attention of the world's communication network.
REQUIRED READING: Click here to go to the CDC WONDER site. When at
that site proceed as follows:
Gonorrhea, GC or the "CLAP", is the most COMMONLY REPORTED STD. It is caused by a G- coccus, Neisseria gonorrhoeae, that attaches to the urethra with special #PILI or FIMBRIAE. The symptoms are VERY DIFFERENT in the male and female. Female symptoms are usually a mild vaginitis that is similar to a variety of other vaginal infections. Because of their mild nature these symptoms may go UNNOTICED and UNTREATED. In the male, pus and swelling in the urethra cause painful & frequent urination which generally elicits an excited visit to a doctor, however 10% of the males are asymptotic (don't show any symptoms). The bacteria may infect the eyes, particularly of babies at birth, and can lead to blindness. Because GC often goes untreated in women, they serve as the MAJOR RESERVOIR. GC often leads to STERILITY in both sexes if left untreated. There is NO IMMUNITY and a cured individual can catch the disease REPEATEDLY. Although GC is still treatable with antibiotics, antibiotic resistant strains are appearing and many physicians fear we will lose the ability to treat this disease with antibiotics. Condoms offer some protection against catching GC. GC can also infect the mouth, throat and anus. Often an individual with GC has several STDs. Some individuals spontaneously recover from a GC infection. Click here () for a discussion from the STD Homepage described above.
This disease, known as NGU, is caused by ANY INFLAMMATION OF THE URETHRA not due to GC. There is often painful urination and a watery discharge. There are 3 to 5 million new cases per year, while life-threatening complications are rare, sterility in women and frequent bladder infections . There are several microbes that may be involved, but the major one is Chlamydia urethritis. However, 75% of the women and 50% of men infected with chlamydia don't have clear symptoms or ignore them until it is too late and they are sterile. The failure to recognize the symptoms and obtain medical treatment contributes to the spread of the disease. Over 3.5 million cases of Chlamydia go undiagnosed and unreported each year in the US. It is the No. 1 STD and the No. 1 cause of sterility. There is no immunity, no vaccine and one may get repeated infections. When diagnosed chlamydia is easily treated and cured. College-age girls (19-24) have the highest rate of infection of any group. Visit this site for more information on Chlamydia.
GET
TESTED |
PULLMAN HAS FREQUENTLY BEEN NUMBER ONE in Washington State in diagnosed C. urethritis. Why do you think this is the case? Is it the water?
Stemming the Silent Epidemic of Chlamydia Sexually transmitted chlamydia infects more than four million people in the United States each year. Many more, perhaps up to 15 percent of the population, may be infected but have no symptoms. Another form of chlamydia causes blindness in more than 60 million people worldwide. Left untreated, the bacteria causes low-grade inflammation that can lead to pelvic inflammatory disease, female infertility, and ectopic pregnancies. Some call it the silent epidemic, one that's sweeping across the world and quietly wreaking havoc. Although there's mounting evidence that infections by Chlamydia bacteria contribute to infertility, arthritis, heart disease, and perhaps Alzheimer's disease, until now there has been no good way to prevent it. But a new oral vaccine, presented April 19, 1998, at the Federation of American Societies for Experimental Biology's Experimental Biology '99 conference, not only protects mice from genital chlamydia infections, it also reduces the joint inflammation that can lead to arthritis |
This STD is cause by the G- spirochete Treponema pallidum. It is transmitted mainly by sexual intercourse. The disease commonly passes through 3 stages; a primary, secondary and tertiary stages. The Primary stage produces a lesion at the initial site of infection, usually on the penis or the wall of the vagina. The initial lesion heals up spontaneously. Many syphilis infections are cured by the natural defense system at this stage. If not, the organism travels to other parts of the body and the secondary stage occurs, producing skin rashes and hair loss. During the secondary stage the patient is highly infectious. In the 3rd stage there usually is involvement of the nervous system leading to the destruction of the brain, insanity, blindness and death. Click here () for a discussion from the STD Home page described above. Recently (1998) the T. pallidum genome has been sequenced.
There are two strains or types of the Herpes simplex virus, type 1 and type 2. Type 1 causes cold sores and mainly infects the mouth region. Type 2 herpes is the genital variety. About 2 weeks after infection of the genitalia lesions, redness, swelling, itching, blisters and a burning occurs in the genital region, including the anus. The blisters crust over in about 3 weeks and disappear. Future attacks last about 5 days. The virus lives in the nerve cells where they remain for life. Some people have frequent attacks, some only one and some have sporadic reoccurrence. Attacks have been tied to stress including the menstrual cycle, illness, fatigue, emotional strain etc. Although type I predominates ABOVE THE WAIST, 20% of the genital herpes is due to this type. The type II predominates BELOW THE WAIST, but it can infect THE MOUTH AREA. A common myth is that if you don't see the blisters you are not infective. This is strictly bull scat spread by people who generally are trying to talk others into having sex with them (run, don't walk from anyone who tells you this as either their intellect or their character is limited). While you may be less infective if no lesions are visible, you can still be infective; i.e., in theory it only takes a SINGLE virus to produce an infection.
The disease is RARELY FATAL in adults, but it is OFTEN LETHAL to new born babies who pick up the infection in the birth canal. Most women with herpes choose to have Cesarean birth to prevent infection of the baby. Certain anti-viral drugs lesson the period of attacks and some people take these drugs prophylactically. There are Herpes Help Groups that put people with herpes in contact with one another for dating etc. Try the Internet for help groups. Anyone who has herpes and doesn't tell their sex partners is not a person of HONOR. Click here () for a discussion from the STD Home page described above.
"Human papilloma virus, also known as HPV, is best known as the cause of plantar warts on feet and hands, a benign infection that is transmitted by normal contact. However, a different, sexually transmitted form of HPV causes genital warts in males and females. More significantly, particular "high risk" types of genital HPV have emerged as the primary cause of 95 percent of cervical cancers. Because it is a virus, researchers are betting on a prophylactic (preventive) vaccine that is now in early trials. Eliminating genital HPV infection could mean preventing the cancer that kills some 9,000 American women each year, say Johns Hopkins researchers, who have been testing such a vaccine for the past year. In the first of two InteliHealth interviews on the vaccine, Richard Roden, Ph.D., assistant professor of pathology at the Johns Hopkins Medical Institutions, explains some of the basic science behind their work
How does the virus seem to trigger the cancer?
After a woman has sex with an infected partner, the virus spreads to the cells lining the genital tract, including the cervix. The infection is painless and usually internal, so most women have no idea they have HPV until a doctor diagnoses it during a routine exam. The virus carries three oncogenes, which together and separately cause infected cells to grow rapidly, creating the warts that are the hallmark of the virus. The high risk, cancer-causing form of HPV has a tendency to integrate within the DNA of the healthy cells, which is associated with progression toward cancer.
Does genital HPV infection always lead to cervical cancer?
No. Several million people, both men and women, are infected with various forms of the virus, but only 15,000 or so cases of cervical cancer are reported each year. In many cases, early stage disease is detected with a gynecological exam and a Pap smear and effectively treated to prevent cancer from forming. The cancer also may not develop in some women because their infection is not high-risk type of HPV, or their immune system does a good job of eliminating or controlling the infection.
How was the vaccine first created?
Since HPV could not be grown in a lab, it was a challenge to create a vaccine without the culprit. But emulating the model of the hepatitis B vaccine, investigators used genetic engineering to create a vaccine consisting of empty viral capsids -- essentially the hollow shell made of the virus's coat protein, without the genetic material inside. They discovered that by injecting this harmless empty capsid into animals, the subjects developed antibodies to the virus. They also found that animals were also protected against their own form of papilloma virus, which was very encouraging."
AIDS is mainly a STD and a disease of intravenous drug (IV) users. As a STD AIDS requires for its transmission that humans be PROMISCUOUS. That is, AIDS is NOT CAUGHT EASILY; it is not transmitted in the air, water, food, insect bites or by contacts between people that doesn't involve the exchange of body fluids. It is caught by an EXCHANGE OF BODY FLUIDS, mainly blood. The cycle of HIV transmission is EASILY BROKEN, at least in theory. In short, AIDS is almost entirely a disease of LIFE STYLE. HIV is a RNA retrovirus. Although their method of replication is interesting, it is beyond the scope of this course.
Although almost everyone has heard of AIDS by now, there is much confusion as to its nature, just how dangerous it is, how you catch it and when and if there will ever be a cure or a vaccination. These subjects will be discussed in this section. The effect of the HIV virus can only be understood through an understanding of the #specific immune system.
For information on AIDS on the Internet visit these sites:
Page on TB & relationship to HIV; Listing of AIDS Web Information; CDC reports on AIDS; Picture of HIV; Drawing of HIV; Another good picture of HIV; HIV replication; Student Project on AIDS: Nova Program on AIDS (need Shockwave and Quicktime helpers);
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The following are some of the major myths that surround the AIDS problem. They are fed by prejudice, plain ignorance, willful ignorance, religious dogma and a human characteristic of trying to make complex things easy. If you have some comment on the following please contact me by e-mail.
AIDS
IS A DISEASE OF HOMOSEXUALS & IS A PUNISHMENT FOR THEIR SINS:
This is a tough one to deal with since the concept of "SIN" is a theological matter, not a scientific
issue. The closest scientific thing to a religious sin might be engaging in BEHAVIOR that has been proven to be PHYSICALLY HARMFUL such as smoking,
overeating, under exercising, excessive drinking of alcohol and engaging in promiscuous
sex. Each of these activities has been proven to lead FREQUENTLY to a DISEASE STATE, and most of us engage in one or more
of these "BIOLOGICAL SINS" to some degree (guess which one(s) I do?). To the degree that homosexuals,
particularly the males, engage in promiscuous, unsafe sex, they contribute significantly
to the spread of the HIV virus.
This situation is not unlike the epidemic of syphilis that struck the world in the 15th century, only in this case it was mostly HETEROSEXUAL PROMISCUOUS sex that rapidly disseminated this disease. The major FLAW IN THIS MYTH is simply that AIDS strikes both homo- and heterosexuals ALIKE once they are infected, by whatever means, with the HIV virus. The growth of the virus and the course of the disease is EXACTLY THE SAME in both groups. It doesn't matter if the victim is a baby whose mother was an IV drug user, a hemophiliac, a surgeon who cut himself during an operation on a HIV carrier, a homosexual male prostitute, a heterosexual female prostitute, or a college student who got drunk and did a stupid thing only once.
AIDS
IS A DISEASE MAINLY OF AFRICAN AMERICANS: There is no doubt that
HIV infection is much higher in poor communities, be they white, black, Asian or Spanish
American. But AIDS is a disease of poverty, ignorance, drugs, life-style and hopelessness.
The HIV virus is equally infective in every race on this planet as far as we know today.
It is truly an "equal opportunity killer".
I
CAN TELL WHO IS LIKELY TO HAVE AIDS; NONE OF MY FRIENDS ARE "DIRTY"; NO ONE I
KNOW WOULD HAVE SEX WITH SOMEONE WITH AIDS ETC.: These are the
myths of people who have decided they WANT TO HAVE SEX with someone and no fact, logic or
reason is going to interfere with their frisky activity; the primitive, reptilian parts of
their brains having effectively eliminated their "reasoning processes". Such
"reasoning" often follows the intake of a pint or so of strong drink in a brief
period of time or an excessive libido. When someone tells you this I would run, not
walk, to the nearest exit, because you're not dealing with someone whose operating
on all cylinders; they are a few cards shy of a full deck; they are half-a-bubble off
plumb; they're missing a CPU. Certainly I would not let such people invest my money for
me, drive my new car or baby-sit my kids. I will give anyone an A in the course if they can provide
me with a foolproof way of telling who is infected with HIV just by looking at them; any
takers?
AIDS
CAN BE CAUGHT BY GIVING BLOOD: Not unless you're using the Fly-By-Night-Vampire
Blood Mobile. If the nurse spit-cleans the site of inserting the needle and
wipes the needle off on her skirt before sticking it in you, you may indeed have a problem
with any number of diseases, including AIDS. However, this doesn't happen with legitimate
blood collecting agencies. To my knowledge no one has ever caught the HIV virus from
GIVING BLOOD.
AIDS
WAS MANUFACTURED BY THE CIA AND KGB TO KILL AFRICAN AMERICANS or BY THE WORLD HEALTH
ORGANIZATION TO CONTROL POPULATION: These are a very prevalent
rumors which exists in several versions (some members of my family believe this story). A
survey in the Fall of 1995 reported that approximately 1/3 of African Am. believe the
first one to be true. While it is THEORETICALLY POSSIBLE to "make" a virulent
virus, we simply don't know enough about the virulence of HIV or any other virus, to
modify it that way, much less to manufacture one that could selectively infect humans of a
certain skin color. What-ever-the-case, the fact that it is EQUALLY VIRULENT to all humans
says something about the POOR QUALITY of any research that produced it (maybe it was the CIA----just
kidding fellows?). If HIV was manufactured, the guys that did it were INCOMPETENT and shouldn't expect the
Nobel Prize committee to consider them.
YOU
CAN CATCH AIDS FROM YOUR ROOMMATE, LAB PARTNER, PERSON WHO SITS BESIDE YOU IN CLASS, FROM
DIRTY DISHES, SHARING A BEER OR FROM THE TOILET: There is always
the off chance that under EXACTLY THE RIGHT KIND of conditions you could catch HIV in one
of the ways described above, but it is HIGHLY
UNLIKELY, unless you are HAVING
SEX with any of those people or they've left their blood behind
on one of these items. Actually the HIV virus seems remarkably difficult to catch. If it
wasn't that millions of humans were enthusiastically working night 'n day trying to give
it to each other, the poor virus would probably not survive for long. If we changed our
behavior we might even see the formation of a "SAVE
THE AIDS VIRUS" (or SAV) organization; they wouldn't ask
you for money, only that you go out and engaged in unsafe sex with a lot of people (Anyone
want to join?). They'd push for laws fining anyone who didn't have unsafe sex at least 10
times a year (5 affairs for married people).
I
CAN ENGAGE IN ALL THE UNSAFE SEX I WANT BECAUSE I CAN'T GET AIDS:
Anyone who thinks this is not just illogical, but is the type of person who would go sky
diving WITHOUT A PARACHUTE and want you to join them. People who think like this (using the word
"think" to describe such a process is an oxymoron) are running on empty; their
one brain cell is asleep, they are from the shallow end of the gene-pool etc.
SOME
PEOPLE CAN'T CATCH AIDS AND SOME PEOPLE SURVIVE AIDS (SO FAR):
This may indeed be true, but it is in the category of saying that "some people
have fallen 3 miles from an air plane without a parachute and survived".
Which, even though it is TRUE, leaves the person who hears it wondering if their hearing
is functioning. Among the ~6 billion people on this planet there are some who have
survived HIV infection for >15 years. Eight individuals have an unusual weakened strain
of HIV that may protect them from the virulent form. However, unless you travel to
Australia where they live and have sex with them, the odds you will contact a NONLETHAL
HIV appear to be so small that this would be you (or me) that to even consider it has to
raise serious questions about one's sanity and intelligence.
The following is a summary of what we know (or think we know) about the HIV virus at the moment and the disease called AIDS. (Sci Am. Aug. pg. 58 1995). As of summer 1998, these facts still appear to be essentially correct.
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Visit this page and take the survey to
find out your RISK for contracting HIV and other STDs.
AIDS is caused by the HIV virus (HIV at Higher magnification; HIV budding out of cell) or Human Immunodeficiency Virus. There are a few other hypotheses kicking around that other agents cause it, including environmental ones (industrial pollution), but there is no SCIENTIFIC EVIDENCE to back any of them up. Obviously #Koch's Postulates can not be used to prove that HIV is the etiological agent of AIDS, since we can not use humans as test animals and our near primate relatives don't seem as susceptible to HIV as are humans. They do suffer from a simian form called SIV. The overwhelming epidemiological, and biochemical data supports the conclusion that HIV is the etiological agent of AIDS. Recently (Nov. 10, 1995) it was reported that the first chimpanzee given the HIV virus has come down with a classical case of AIDS after 9 years.
AIDS is a disease of the immune system. Its method of attack is DIABOLICAL. If the Hollywood version
of the "evil scientist" were to design the perfect pathogen it would resemble
the HIV virus. For example, most HIV positive individuals progress to AIDS over a 10 to 15
year period, during most of that time they are reasonably healthy, capable of being
sexually active, and HIGHLY INFECTIVE. These 6 to 10 years of infectivity perfectly serve
the requirements of an efficient pathogen; one that doesn't kill its host before it can
pass the pathogen on. Further, the fact that the HIV virus is not highly infectious
actually supports its subtle, but effective spread; i.e., by spreading out the time of
transmission it insures that large "clusters" of victims don't die all at once
and produce a "shock effect" that might change people's sexual behavior. For an
excellent report, prepared by a student and complete with great animations, on the life
cycle of AIDS visit this site.
We now know that HIV has the #FASTEST MUTATION RATE of any virus known. This means that it can change its antigenicity rapidly, developing new varieties quickly to meet new immunological and drug treatment challenges. But how does HIV cause AIDS and why does the disease progress so slowly? Within these questions apparently lie the terrible secret of the success of HIV.
The problem with HIV lies not so much in an initial failure of our immune system, rather it is that HIV has developed a way to subvert and ultimately destroy the immune system:
HIV infect usually occurs via an intimate exchange
of body fluids, most often blood or semen. These exchanges generally occur via sexual
intercourse (anal or vaginal), use of contaminated needles during drug injections or by
mother to fetus transmission.
The HIV is an enveloped retrovirus virus with RNA as its genome. It has a complex structure.
The virion contains the enzyme, reverse transcriptase that copies the RNA genome into DNA
which is inserted into the host genome. These genomic copies of the HIV are subsequently
transcribed into strands of genomic RNA.
Upon infection with HIV the body
recognizes a foreign agent and immediately launches a vigorous counterattack. First, #macrophages and related cells engulf and digest the HIV
into smaller proteins.
The HIV epitopes are presented to the
special #T HELPER CELLS or HELPER T LYMPHOCYTES (Th cells). The
Th cells secrete chemicals (messages) that stimulate the appropriate epitope-recognizing
Tk and B cells to proliferate. The B cells proliferate and differentiate into #plasma cells and begin secreting large quantities of
antibody against the infective HIV strain. The Tk cells or killer T lymphocytes seek out,
attack and kill any cells that harbor HIV antigen on their cell surface. The
HIV-antibodies bind to these infected cells and target them for destruction by complement
and Tk cells.
The HIV can only infect cells that
present a particular set of receptor molecules on their cell surface; the CD4 receptor
complex. Since Th cells carry this receptor they are a major target for the HIV. The
infected Th-cells initially die by the thousands, until the Tk cell and HIV-antibodies are
produced and counterattack. Victims may show some mild to severe (e.g. flu-like) symptoms
during this early attack. However, many show no symptoms and they all recover and remain
SYMPTOM-FREE for an extended period. Such people are fully infective and just like you or
me, look healthy and their sex drive is as strong as anyone else's.
During the second phase the immune
system continues to function well (this is the phase Magic Johnson is currently in). How
then does HIV survive? Why isn't it DESTROYED
COMPLETELY early in the struggle? The virus level remains low,
however the NET VIRUS LEVEL begins to slowly increase and the helper T cells continue a SLOW DECLINE. The
decline is apparently brought about by a COMBINATION of the effects of HIV infection and
destruction of the Th by the Tk cells they have activated. Recall however, that the Th
cells are required for the ACTIVATION OF BOTH the Tk and B cells.
It turns out that the reverse transcriptase
that makes DNA from retrovirus RNA is seriously error prone. This means that it makes more
mistakes (mutations) than any virus known. To understand the significance of this we must
invoke the #theory of evolution The high mutation rate means that
HIV has a tremendous evolutionary potential.
This evolutionary potential is seen in
the production of mutant strains of HIV that are no longer recognized AS FOREIGN by the immune system,
thus they escape destruction. These mutant strains are able to infect Th cells and to
produces more HIV. As soon as the immune system recognizes the mutant as a danger it
responds as described above. But there is a difference, and that is that the immune system
is now weakened by the loss of Th cells so its response is slower and less effective.
Figure 2. The evolutionary cycle of HIV mutation. Mutants arise spontaneously. A rare mutant is not recognized by the immune system and is able to infect more Th cells. This mutant is eventually recognized as foreign antigen and an attack is mounted against it. However, new mutations continually arise until the bulk of the Th cells are destroyed (as shown by some viruses escaping destruction by a weakened immune system in bottom left) and the immune system collapses.
The cycles of mutation producing new
strains, re-infection and fresh replication of the new HIV strain followed by a response
by the damaged Immune system. The cycles continues relentlessly while the numbers of Th
cells drop inexorably lower and lower.
When Th count reaches 200 cells per
microliter (10-6 liter) from a high of ~1000, a victim's fate is sealed and
full blown AIDS ensues. The viral level climbs sharply and all the indicators of immunity
(e.g. antibody level, Th cells etc.) drop precipitously. Untreated victims rarely survives
for more than two years after this stage is reached. However, with the release of the
newest drugs in the battle against AIDS, the protease inhibitors, many people near-death
with AIDS have made dramatic recoveries and have been able to resume their normal lives.
How long they will remain healthy remains to be determined.
Death occurs when the victim succumbs
to opportunistic
infections that overwhelm the victims last defenses.
For another discussion of HIV and AIDS visit this site. It has lots of excellent pictures.
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The approaches to dealing with AIDS fall into three categories:
PREVENTION OF INFECTION
CURING THE INFECTION
LIVING WITH THE INFECTION
At the present time (Spring 1998) only the third approach has shown ANY ENCOURAGING SIGNS OF SUCCESS. A series of new drugs were recently (Spring '96) released which suggest the possibility of living longer with the HIV infection; that is they may retard the onset of AIDS and even reverse the course of the symptoms. Since their introduction they have helped many of the AIDS patients who have taken them. In fact the death rates from AIDS has fallen within the last year and much of this decline has been attributed to these new drug combination. Some people near death from AIDS have made remarkable recoveries and currently appear healthy; many of them have returned to work and are making plans for the future for the first time in years. In a few cases HIV can no longer be detected in their blood by any tests we have today. Further, research results are suggesting that the earlier the treatment the longer it takes for AIDS to develop. With a battery of drugs that attack the HIV at a variety of stages, the chance of HIV mutants developing decreases. No one is yet willing to say that any HIV host has been CURED of the virus, but the medical community is cautiously talking about the possibility of living long-term with the disease. Most HIV-scientists fully expect that mutant strains of the virus will appear that are resistant to the new battery of drugs and some victims have not been helped by these new treatments. Recent findings indicate that none of these new drugs "cure" AIDS although they do lower the HIV level to very low levels in some patients and scientists have recently (fall '98) found that the HIV is able to hide in resting immune cells indefinitely and to return to an active stage when the resting cell is reactivated. Most scientists feel that a cure is very far off at best and is unlikely to ever be achieved; the picture is currently very dark.
Other drugs have had the effect of making the late stages of an AIDS's victim less painful and there has been some success at fighting certain of the most common opportunistic infections that afflict those in their final stages. The drug AZT inhibits the transfer of HIV from the infected mother to the fetus if given early in pregnancy and decreases the number of newborns that are infected with HIV.
Drugs like AZT are aimed at inhibiting the HIV enzyme reverse transcriptase, which is unique to viruses like HIV. This enzyme is crucial to the replication of the virus; if it is inhibited the virus dies. The newer drugs, protease inhibitors, prevent the virus from maturing. That is, the viral mRNA directs the synthesis of a number of proteins that are required for the virus to mature. However, these proteins are translated as one continuous long protein molecule that must be cleaved by specific viral-induced proteases into segments that can fold into the final functional shape required to form a mature, infectious virus. Because both reverse transcriptase and the protease enzymes are unique to HIV they are reasonable points to attack the virus. However, the rapid mutation rate of HIV results in it becoming resistant to AZT within ~18 months on average. Another approach being actively pursued involves inhibiting the binding of the virus to the target cells; to blocking or otherwise stopping the binding of HIV to the unique receptors on the targeted host cells. Drugs using this approach are "in the pipeline" and may appear within a couple of years.
A number of vaccines are being tested, but all previous attempts to develop a vaccine have failed. Even if a vaccine is discovered it will not help the >30 million people already infected with HIV. An effective HIV vaccine would require a massive effort by the UN to inoculate several billion people at a cost of millions of taxpayer-dollars. Would you be willing to help pay for it?
As discussed above the most logical, simplest and most effective approach would be a CHANGE IN THE SEXUAL BEHAVIOR OF HUMANS. That this can work has been shown by the effects of an aggressive educational campaign among the American homosexuals. In the 1980s the homosexual community sought to educate that group in safe sexual practices. It appears to have been successful as the number of new AIDS cases among homosexuals FELL SIGNIFICANTLY. However, as older homosexuals have died from AIDS and the numbers of gays with AIDS declined, the younger gays are reported to have lost their fear of this disease and there is evidence that the old ways of unsafe sex are returning.
The problem of "safe-sex education" is complicated by
religious, political and moral views that feel that anything but TOTAL SEXUAL ABSTINENCE is 
UNACCEPTABLE and that all sex education, except
that taught by parents, is inappropriate. Such groups also feel that it is immoral to
teach people how to use condoms or any other safe-sex procedures because of the common
belief that it promotes immoral behavior. However, all the data show that this is not the
case; i.e., teenagers who are taught sex education, including the use of condoms are not
any more sexually active (or less) than those kept ignorant.
Do you have views on this subject? If so E-mail them to me, along with your e-mail address and I'll post them on the Internet if they are not offensive. If you present me with a well crafted, thoughtful, reasoned and well written (one pg. 12pt) presentation of your views I will give you a maximum of 4 extra credit points. However, I am the ultimate judge and my standards are high.
Right now the future of AIDS is anyone's guess. The world's HIV-infection numbers are currently (Fall 1996) estimated to be ~30 million (spring '98). HIV infections are #pandemic and there is apparently no place in the world that is free of this disease. In parts of central Africa it is a raging epidemic resulting in whole villages being abandoned because almost everyone has died of AIDS. Further, millions of children have become orphans because all their adult family members have died of AIDS. HIV infection is extremely high in the large population centers in central Africa where less than one dollar per person per year is spent on health care. Many governments in Africa refuse to admit that there is a serious HIV problem or even that there is any problem for fear of losing tourist dollars or causing unrest among their population. In the recent bombings of the American embassies in Africa it was felt necessary to fly in blood from the US or Europe because the African blood supply is not considered safe.
Southeast Asia and India are predicted to be the next centers of AIDS outbreaks. In Thailand over 1 million people out of a population of 60 million are infected with HIV. There they have found infection rates of 38% in commercial sex workers, 12% in Royal Thai Army recruits and 16% among men using STD clinics. In Asia HIV infection is almost EXCLUSIVELY HETEROSEXUAL in nature and the virus seems to have evolved to be more infective in the heterosexual situation. The Thai government has undertaken an extensive educational program of safe sexual practices which is reported to be having a significant positive affect.
Further, new strains of HIV are being reported, some which seem better able to establish an infection via the vaginal route and others the anal route. It would appear that either #evolution is working pretty much as predicted or, if you believe that the CIA/KGB made the virus, they are still at it and someone should find out where they're doing this work and ask them to please stop (I'm being sarcastic here folks, so don't take that last statement seriously).
One hope (Sci. Nov. 1995) that has recently (6/99) been shattered was the observation that, 8 people in Australia that were infected with a weakened mutant of HIV 17 years ago didn't develop AIDS when expected, have begun to develop AIDS. It was hoped that these people might have a weakened HIV that made them resistant to the virulent form of HIV. It was speculated that this weakened form of HIV, or some derivative of it, might serve as a LIVE VACCINE to immunize people against HIV. This dream, like many others before it, has now evaporated.
In 1998-99 a whole host of immunization tests are underway. Unfortunately the results will not be known for some years, so we are all going to have to continue to be very careful who we have sex with. If you are not too smart maybe you could volunteer to be a test subject, in which case they would give you the POSSIBLE VACCINE then you could go out and have unprotected sex with everyone you could and after a few years you could become a nameless statistical number in the A column ("Wow, no sign of HIV, maybe the vaccine works") or the B column ("whoops, you have a HIV infection, sorry. Guess we have to go back to the laboratory"). Recently the HIV genome has been found to reside in MEMORY CELLS (CD4T) which can survive for as long as 10 or more years. In this state the HIV hides from the antiretroviral drugs. However, attempts are underway to "flush" out these HIV-infected-memory cells by activating them so that the virus in them becomes susceptible to antiretroviral drugs.
FAQ by WELL BEHAVED but scientifically illiterate people: "why should I worry about a bunch of people who willfully and knowingly engage in unsafe sex and/or shoot up drugs? Maybe the best thing to do would be to let them get on with committing suicide and let that solve the problem!"
ANSWER: Well that attitude might be all right if biology wasn't involved or if the person asking that question never had to worry about meeting other humans. However, there are serious public health CONSEQUENCES if nothing is done about HIV.
THE COST: It now costs
>$120,000/year to treat a person with AIDS and that cost is usually borne by (fill in
your name) society. It doesn't take a rocket scientist to multiply the number of HIV
infected people by $120,000 to come up with a rather humongous, I mean seriously huge,
like mind-boggling monstrously BIG, number that has to come out of our pockets. At a time
when society is trying to limit spending on medical care, it would seem this presents
somewhat of a fiscal (and ethical) dilemma. Treatment of persons infected with HIV costs
~$20,000/year and again guess who ends up paying most of this bill.
TUBERCULOSIS: The TB bacterium is,
unlike HIV, ridiculously easy to catch. Further, it is tough as nails and lasts one
hellish long time outside the host. TB is spread through the air, food and water. Finally,
if you're not pale, and feeling sick to your stomach yet, consider that new antibiotic
resistant forms of TB have developed which makes treatment virtually impossible. There is,
however good news about this problem. Public health organizations all over the US have
aggressively sought out victims of TB (often homeless people) and aggressively treated
them. The result is that deaths from TB in the US have declined significantly in the past
couple of years. However, again this takes money to run these programs and where is it
going to come from? If you were to become a Public Health Worker what salary would you consider reasonable for chasing around
bad neighborhoods getting people with TB to take their medication? However, all of this
cost millions of dollars of taxpayer money.
"What does this have to do with AIDS anyway?" you alertly ask? Gee I'm glad you asked that question (pick your bribe up after class); let me tell you a SHORT STORY with a definite MICROBIAL TWIST--see story below.
ONCE UPON A TIME in a rich and prosperous land there were all these sick people with this nasty disease called AIDS, which the good and decent people of this great land didn't get (they told ourselves) because they are so darn cute, neat and, well, just plain wonderful. However, the evil witch, Mother Nature and her toady companion Evolution, didn't think those good people were all that wonderful except as nutrient-rich mobile-lumps of juicy meat. So the two of them brewed up something rather nasty to get their attention. It seems that people who have AIDS are immunologically #COMPROMISED (but you knew that) and all sorts of microbes love to grow in them, including the TB bacillus. So when Joe, one of our friendly, homeless AIDS patients, goes in for treatment at the local free-clinic, it's found that he has a bloody awful fulminating, like seriously uncool, case of TB (bummer!). Antibiotics are prescribed and Joe is told that he has to take the medication every day for the rest of his short miserable, pain filled life. Poor Joe stumbles out of the clinic, takes the crowded subway and, being at heart a friendly, sharing person, infects the 50 or so of the better citizens pressed up against him with his hungry TB guest. He's rather depressed at the additional rotten news, so he goes on a two-week drunk & forgets to take his medication. But he has taken just enough to begin to select out #RESISTANT STRAINS OF HIS TB BACILLUS. He doesn't bother to return to the clinic to pick up more TB medication since he knows he's going to die soon and they can't do anything about it. In the meantime he's become a one-man-coughing-walking-sitting-beside-you/me-on-the-bus/subway/movie foci of antibiotic resistant TB. Joe will be remembered by many of the citizens of that mythical land when they get their next chest X-ray and find out that he's left them with something that just keeps on giving. |
So what do we, as a society, do with the many Joes out there in our land? Do we leave those with HIV infections to the not-so-tender mercies of mother nature, who uses Joe and his buddies as walking cultures for things like new strains of TB and other nasty microbes which may eventually infect us? See report on recent spread of TB. Oh, by the way about 30% of the humans on earth are already infected with TB and strains of TB resistant to all the antibiotics used to treat it are becoming common. It is one of the major causes of death from infectious disease. So I'll ask you again: How much would you pay to be protected from this nasty microbe?
THE
LOSS OF TALENT: AIDS has taken a terrible toll of creative male
homosexuals in this country and is on its way towards taking many lives of young
heterosexuals around the world. Is this a loss we want to have happen? Will the world be
better off with the death of MANY BRIGHT, TALENTED, CREATIVE young people, who, after all,
are our brothers, sons, cousins and uncles?
DISRUPTION
OF SOCIETIES: As societies have to expend increasingly amounts
of their limited resources in caring for those ill from AIDS and related diseases (e.g.
TB), and as many of its CREATIVE young professionals die from AIDS, it will DESTABILIZE
these societies once those costs exceed a certain amount. For example, they will not be
able to pay off their international debts which may, in turn, disrupt the world's banking
system. Since the world's economy seems to be IRREVOCABLY LINKED, can the US expect to
avoid problems from disruptions in banking and trade?
SHIFTING
OF RESOURCES TO MEDICAL CARE FROM OTHER NEEDS: As limited
resources are required to treat a burgeoning ill population, this takes money and manpower
from other creative activities such as education, maintaining the industrial
infrastructure, research etc.
An AIDS lecture for medical students. Lots of good links to more information, but statistics are out-of-date (1996).
In writing this section I have tried to walk a fine line between acute depression and despair, and education. AIDS is perhaps the most SERIOUS PROBLEM to face mankind since the possibility of an Atomic Holocaust during the Cold War. It is very difficult to learn about this problem and not be discouraged. The solution seems so tantalizingly close, yet it remains out of reach because we are prisoners of our human nature. We appear to be in a race between education and reason on the one hand and ignorance and blind, sexual instinct on the other, and the former seems to be losing, at least at the moment. If you have any workable suggestions or thoughts on the subject please share them with me & I will use my judgment to pass them on to the readers of these files. Thank you.
There is some good news and there is cautious hope that maybe we are not losing the battle quite as fast as we once were. But this is only true in the Western world; in the developing world the AIDS holocaust is gaining speed at an alarming rate.
There are a number of other important STDs, ~28 total, that we don't have time to cover in this course. These include Hepatitis B, and papilloma virus. If you want to know as much as your doctor about other STDs visit these lecture sites: #1, #2, #3, #4.
The prevention of STDs is actually VERY
SIMPLE. It doesn't require morals, ethics, that you be a religious or non-religious
person, or that you are even a law abiding person. It does require that you HAVE KNOWLEDGE and that you UTILIZE THAT KNOWLEDGE (get real
folks). The microbes that are responsible for STDs all depend upon humans ENGAGING IN OODLES OF UNPROTECTED SEX
to transmit them. Without that seductive activity most STDs would VIRTUALLY DISAPPEAR from
the earth in one or two generations. It appears that the microbes evolve to take advantage of naughty human behavior
not vice versa. The following is a list of simple steps you can take to minimize your
chances of contracting a STD (please avoid laughing until you've finished reading them).
Avoid having sex until marriage and
then remain MONOGAMOUS
within the marriage (I'm serious, no really--hey, people really do do that!!). Look up the
word "VIRGIN" in the dictionary
just for the fun of it.
Know the ENTIRE SEXUAL HISTORY of
everyone with whom you are going to have sexual intercourse (IT IS BEST TO ASK THEM THIS
BEFORE REMOVING ANY CLOTHING--oh, don't take notes as that's off-putting). Remember that
MICROBIOLOGICALLY you are having sex with EVERYONE your partners have had sex with in their past (YUCK!!!--"Remember the time you got plastered and woke up naked in bed
with...."). When you buy a used car you probably inquire into
its history and it can't give you a fatal disease.
Individuals planning to have sex
together should be checked for STDs, including an AIDS test, and, if either has had sex
with anyone else, they should NOT HAVE SEX with anyone for three to
six months before having a second AIDS test to VERIFY that BOTH ARE FREE of the HIV virus.
(This defines WILL POWER or a high EQ [emotional quotient]).
Never have UNPROTECTED sex unless you
have followed I through III. Condoms offer some degree of protection against all STDs.
However, the "heat of passion" often renders condoms less effective.
I'm sorry that I can't offer you any easy answers to A VERY DIFFICULT PROBLEM. I am very aware that the ABOVE CHOICES are, in today's social & moral climate, so difficult as to render them almost comical. However, I know some people who have followed these rules and they seem perfectly normal, well adjusted, sexually satisfied, amazingly happy and, best of all, STD-free. However, the characteristics of the STDs don't leave me any alternatives. You may choose not to take the above advice seriously, but that's like sky-diving without a parachute (SPLAT!!).
Trichomonas vaginalis: Ugly thing isn't it? ASM site & CDC site
Copyright © Dr. R. E. Hurlbert, 1999.
This material may be used for educational purposes only and may not be duplicated for
commercial purposes.
SCIENCE HALL, ROOM 440CA
PHONE: 509-335-5108
FAX: 509-335-1907
E-mail address: hurlbert@wsu.edu or hurlbert@pullman.com
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