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AIDS - What's new ? ------------------- Is the message getting through? We already know enough about AIDS to prevent its spread, but ignorance, complacency, fear and bigotry continue to stop many from taking adequate precautions. We know enough about how the infection is transmitted to protect ourselves from it without resorting to such extremes as mandatory testing, enforced quarantine or total celibacy. But too few people are heeding the AIDS message. Perhaps many simply don't like or want to believe what they hear, preferring to think that AIDS "can't happen to them." Experts repeatedly remind us that infective agents do not discriminate, but can infect any and everyone. Like other communicable diseases, AIDS can strike anyone. It is not necessarily confined to a few high-risk groups. We must all protect ourselves from this infection and teach our children about it in time to take effective precautions. Given the right measures, no one need get AIDS. The pandemic continues: ----------------------- Many of us have forgotten about the virulence of widespread epidemics, such as the 1917/18 influenza pandemic which killed over 21 million people, including 50,000 Canadians. Having been lulled into false security by modern antibiotics and vaccines about our ability to conquer infections, the Western world was ill prepared to cope with the advent of AIDS in 1981. (Retro- spective studies now put the first reported U.S. case of AIDS as far back as 1968.) The arrival of a new and lethal virus caught us off guard. Research suggests that the agent responsible for AIDS probably dates from the 1950s, with a chance infection of humans by a modified Simian virus found in African green monkeys. Whatever its origins, scientists surmise that the disease spread from Africa to the Caribbean and Europe, then to the U.S. Current estimates are that 1.5 to 2 million Americans are now probably HIV carriers, with higher numbers in Central Africa and parts of the Caribbean. Recapping AIDS - the facts: --------------------------- AIDS is an insidious, often fatal but less contagious disease than measles, chicken pox or hepatitis B. AIDS is thought to be caused primarily by a virus that invades white blood cells (lymphocytes) - especially T4-lymphocytes or T-helper cells - and certain other body cells, including the brain. In 1983 and 1984, French and U.S. researchers independently identified the virus believed to cause AIDS as an unusual type of slow-acting retrovirus now called "human immunodeficiency virus" or HIV. Like other viruses, HIV is basically a tiny package of genes. But being a retrovirus, it has the rare capacity to copy and insert its genes right into a human cell's own chromo- somes (DNA). Once inside a human host cell the retrovirus uses its own enzyme, reverse transcriptase, to copy its genetic code into a DNA molecule which is then incorporated into the host's DNA. The virus becomes an integral part of the person's body, and is subject to control mechanisms by which it can be switched "on" or "off". But the viral DNA may sit hidden and inactive within human cells for years, until some trigger stimulates it to replicate. Thus HIV may not produce illness until its genes are "turned on" five, ten, fifteen or perhaps more years after the initial infection. During the latent period, HIV carriers who harbour the virus without any sign of illness can unknowingly infect others. On average, the dormant virus seems to be triggered into action three to six years after first invading human cells. When switched on, viral replication may speed along, producing new viruses that destroy fresh lymphocytes. As viral replication spreads, the lymphocyte destruction virtually sabotages the entire immune system. In essence, HIV viruses do not kill people, they merely render the immune system defenceless against other "opportunistic: infections, e.g. yeast invasions, toxoplasmosis, cytomegalovirus and Epstein Barr infections, massive herpes infections, special forms of pneumonia (Pneumocystis carinii - the killer in half of all AIDS patients), and otherwise rare malignant tumours (such as Kaposi's sarcoma.) Cofactors may play a crucial contributory role: ----------------------------------------------- What prompts the dormant viral genes suddenly to burst into action and start destroying the immune system is one os the central unsolved challenges about AIDS. Some scientists speculate that HIV replication may be set off by cofactors or transactivators that stimulate or disturb the immune system. Such triggers may be genetically determined proteins in someone's system, or foreign substances from other infecting organisms - such as syphilis, chlamydia, gonorrhea, HTLV-1 (leukemia), herpes, or CMV (cytomegalovirus) - which somehow awaken the HIV virus. The assumption is that once HIV replication gets going, the lymphocyte destruction cripples the entire immune system. Recent British research suggest that some people may have a serum protein that helps them resist HIV while others may have one that makes them genetically more prone to it by facilitating viral penetration of T-helper cells. Perhaps, says one expert, everybody exposed to HIV can become infected, but whether or not the infection progresses to illness depends on multiple immunogenic factors. Some may be lucky enough to have genes that protect them form AIDS! Variable period until those infected develop antibodies: -------------------------------------------------------- While HIV hides within human cells, the body may produce antibodies, but, for reasons not fully understood, they don't neutralise all the viruses. The presence of HIV antibodies thus does not confer immunity to AIDS, nor prevent HIV transmission. Carriers may be able to infect others. The usual time taken to test positive for HIV antibodies after exposure averages from four to six weeks but can take over a year. Most experts agree that within six months all but 10 per cent of HIV-infected people "seroconvert" and have detectable antibodies. While HIV antibody tests can indicate infection, they are not foolproof. The ELISA is a good screening test that gives a few "false positives" and more "false negatives" indicating that someone who is infected has not yet developed identifiable antibodies.) The more specific Western Blot test, done to confirm a positive ELISA, is very accurate. However, absence of antibodies doesn't guarantee freedom form HIV, as someone may be in the "window period" when, although already infected, they do not yet have measurable levels of HIV antibodies. A seropositive result does not mean someone has AIDS; it means (s)he is carrying antibodies, may be infectious and may develop AIDS at some future time. As to how long seropositive persons remain infectious, the June 1987 Third International Conference on AIDS was told to assume "FOR LIFE". What awaits HIV-carriers who test positive?: -------------------------------------------- On this issue of when those who test HIV positive will get AIDS, experts think that the fast track to AIDS is about two years after HIV infection; the slow route may be 10, 15, or more years until symptoms appear. Most specialists agree that it takes at least two years to show AIDS symptoms after HIV infection, and that within ten years as many as 75 per cent of those infected may develop AIDS. A report from Atlanta's CDC based on an analysis of blood collected in San Francisco from 1978 to 1986, showed a steady increase with time in the rate of AIDS development among HIV-infected persons - 4 percent within three years; 14 percent after five years; 36 percent after seven years. The realistic, albeit doomsday view is that 100 percent of those who test HIV-positive may eventually develop AIDS. Still spread primarily by sexual contact: ----------------------------------------- AIDS is still predominantly a sexually transmitted disease: The other main route of HIV infection is via contaminated blood and shared IV needles. Since the concentration of virus is highest in semen and blood, the most common transmission route is from man to man via anal intercourse, or man to woman via vaginal intercourse. Female HIV carriers can infect male sex partners. Small amounts of HIV have been isolated from urine, tears, saliva, cereb- rospinal and amniotic fluid and (some claim) breast milk. But current evidence implicates only semen, blood, vaginal secretions and possibly breast milk in transmission. Pregnant mothers can pass the infection to their babies. While breastfeeding is a rare and unproven transmission route, health officials suggest that seropositive mothers bottle feed their offspring. AIDS is not confined to male homosexuals and the high risk groups: There are now reports of heterosexual transmission - form IV drug users, hemo- philiacs or those infected by blood transfusion to sexual partners. There are a few reported cases of AIDS heterosexually acquired from a single sexual encounter with a new, unknown mate. And there are three recent reports of female-to-female (lesbian) transmissions. Spread of AIDS among drug users alarming: ----------------------------------------- In many cities, e.g. New York and Edinburgh, where IV drug use is wide- spread, IV drug users often share blood-contaminated needles. In New York, more than 53 percent of drug users are HIV-infected and may transmit the infection to the heterosexual population by sexual contact and transmission from mother to child. Studies in Edinburgh, where 51 percent of drug users are HIV-infected, show that providing clean needles isn't enough to stem infection. Even given free disposable needles, many drug abusers preferred the camaraderie of shared equipment. Only with added teaching programs and free condom offers, are educational efforts likely to pay off. In New Jersey, offering free treatment coupons plus AIDS education brought 86 percent of local drug users to classes. A San Francisco program issued pocket-size containers of chlorine bleach to IVDAs with instructions on how to kill HIV viruses. The Toronto Addiction Research Foundation notes a similar demand for AIDS information. Risk of infection via blood transfusion very slight: ---------------------------------------------------- Infection by blood transfusion is very rare in Canada today. As of November 1985, the Red Cross, which supplies all blood and blood products to Canadian hospitals, had routinely tested all blood donations for the HIV antibody. In 1986, when we last discussed AIDS, the Red Cross reported the incidence of HIV-positive blood samples as 25 in 100,000. Now, at the start of 1988, only 10 per 100,000 blood samples are found to be infected - which, of course, are discarded. Only a tiny fraction of HIV-positive blood (from HIV-infected people who haven't yet developed detectable antibodies) can now slip through the Red Cross screening procedure. The minimal risk is further decreased by screening methods, medical history-taking, questionnaires and donor inter- views. Very few people at risk of AIDS now come to give blood. The "self- elimination form", filled out in a private booth, allows any who feel compelled by peer pressure to donate blood, total privacy to check the box that says "Do not use my blood for transfusion." As to banking one's own blood, or autologous donations, the Red Cross permits a few "medically suitable" people, referred by their physician, to store their blood if they are likely to need blood transfusion in upcoming elective surgery. They can bank up to four units of blood, taken in the five weeks before surgery. Finally - it can be categorically stated - IT IS ABSOLUTELY IMPOSSIBLE TO GET AIDS BY GIVING BLOOD!!! Minimal risk to health care workers: ------------------------------------ While health care personnel face a slight risk of HIV infection, all cases reported to date have been due to potentially avoidable mishaps or failure to follow recommended precautions. Of thousands caring for AIDS patients worldwide, only a tiny percentage has become infected, and so far no Canadian health personnel have become HIV-infected. A survey done by the Federal Centre for AIDS (FCA) of 50 workers occupationally exposed to AIDS showed that none became infected. A british hospital study on staff looking after 400 AIDS patients over several years found none who became HIV-positive. In one U.S. survey, 7 out of 2,500 health care workers seroconverted and developed HIV antibodies all by potentially avoidable accidents such as needle pricks, exposure to large amounts of blood, body fluids spattered into unprotected mouth, eyes or open sores. The reported mishaps underscore the need for rigorous, vigilant compliance with preventive guidelines. Universal body substance precautions (BSP) urged: ------------------------------------------------- The newest guidelines suggest that every health care worker, including dentists, should handle all blood and body fluids as if infectious. Testing all patients for HIV is not practical and does not confer protection. Rely- ing on tests that are not 100 per cent accurate would only induce a false sense of security. Rather than trying to identify infected persons, the CDC and Ottawa's FCA now promote a philosophy that regards all patients as potentially infected. (At Johns Hopkins in Baltimore, about six percent of admissions to the Traumatic Emergency Unit recently tested HIV-positive.) Hospital and health care workers (including those caring for patients at home) are encouraged to "think AIDS" and protect themselves. All patients should be handled in a way that minimizes exposure to blood and body fluids, e.g. by always wearing gloves when touching open sores, mucous membranes, taking blood, attending emergencies, putting in IV needles, touching blood- soiled items, with scrupulous hand-washing between patients (and whenever gloves are removed), wearing masks, eye protection, plastic aprons and gowns when appropriate. Taking such precautions will not only protect against AIDS but also against more infectious agents such as hepatitis B and some hospital acquired infections. We are all being forced to remember stringent anti- infection rules! Absolutely no evidence of spread by casual contact: --------------------------------------------------- All the research to date points to the fact that AIDS is not very easy to catch. One University of Toronto microbiologist speculates that those with high antibody counts are probably not very infectious. The most infectious appear to be seemingly healthy persons carrying HIV without any sign of disease as yet. AIDS CANNOT BE PICKED UP CASUALLY via doorknobs, public washrooms, shared school books, communion coups, cutlery or even by food handlers with open cuts. A relatively weak virus, HIV is easily killed by a dilute 1 in 10 solution of Javex/bleach, rubbing alcohol and other disinfectants. Even where parents or caregivers have cleaned up HIV-infected blood, vomit or feces, HIV has not been transmitted. It is perfectly safe to share a kitchen, bathroom, schoolroom or workbench with HIV-infected individuals. But it is inadvisable to share toothbrushes, razors, acupuncture needles, enema equip- ment or sharp gadgets, which could carry infected blood through the skin. ORDINARY, NONSEXUAL WORKPLACE AND CHILDHOOD ACTIVITIES DON'T TRANSMIT AIDS. The rare exception might be direct blood-to-blood contact via cuts or wounds if infected blood (in considerable amounts) spills onto an open sore. Even in such cases a swab with dilute bleach can kill HIV viruses. Not spread by mosquitoes and other insects: ------------------------------------------- There's no evidence of HIV transmission by insects. Researchers report that the AIDS virus cannot multiply or survive inside a mosquito. The infection pattern in Africa - where children who are not sexually active might be expected to have AIDS if mosquito bites were a real threat - shows no sign of insect transmission. Vaccines still a way off: ------------------------- Scientists caution that a safe, effective vaccine against HIV may be at least a decade away, mainly because, like the influenza virus, HIV mutates (changes structure) quickly, producing different strains. (Several different HIV strains have already been isolated.) An ideal vaccine must be able to stimulate neutralization of both "free" viruses and those hidden within lymphocytes, such as T-helper cells. Researchers in various countries have developed and are testing a few preliminary vaccines. One sub-unit vaccine, made from virus coat material (a glycoprotein) genetically cloned in an insect virus (the baculovirus, which attacks moths and butterflies but no humans) has been shown to stimulate an immune response in experimental animals. Another preliminary vaccine, produced by cloning modified Vaccinia viruses, containing a portion of HIV envelope, is about to enter clinical trials in New York. (It would be applies, like the old smallpox vaccine, into a small scratch.) But to date no vaccine tried in animals or humans has been shown to prevent AIDS. Testing no solution: -------------------- Large scale, screening of the public for HIV antibodies offers little pro- tection because today's apparent negatives can become infected tomorrow or test seropositive when antibodies develop in those already harboring HIV. Reliance on tests could lull people into false complacency. A "false nega- tive" result may fool someone into risky sexual behaviour. Curiously, despite a widespread demand for tests, especially among high-risk groups, a study in Pittsburgh showed that 46 percent of a group of homosexual/bisexual men tested did not return for or want their antibody test results. Many health experts therefore believe that mandat

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