Section II HIV Overview Human immunodeficiency virus (HIV) attacks and destroys the cells of the immune system. An HIV infection can weaken a person’s immune system un- disease. This state is known as immune deficien- cytil it is no longer capable of fighting infection and person becomes vulnerable to opportunistic infec- tions. When someone is severely immunodeficient, the the weakened immune system. HIV is spread by the , which are infections that take advantage of unprotected sexual intercourse. In its most ad- Protests in the 1980s called for more research to exchange of bodily fluids, most commonlyacquired through fight AIDS. immunodeficiency syndrome (AIDS) vancedby the occurrencestages, HIV ofinfections an opportunistic can lead toinfection or - , defined tem of this previously healthy woman suddenly AIDS takes on average ten years to develop. With physicians were baffled: why had the immune sys HIV-related cancer. In the absence of treatment, An autopsy revealed that she had pneumocystis span and never progress to AIDS. Although there is pneumoniaceased to function? Rask died on December 12, 1977. treatment, though, people can live a near normal life , an extremely rare fungal infection. through effective medication. from a mysterious new syndrome began sprouting no cure for HIV/AIDS, the disease can be managed Over the next few years, more rare maladies - History up, mainly among homosexual men. In cities such as Copenhagen, New York, Los Angeles, and San Fran seven-year-old physician who had spent the last Kaposi’s sarcoma cisco, young men fell ill from an aggressive form of fourIn years November practicing of 1977, in a Dr.run-down Grethe Rask,clinic in a forty-Zaire , an uncommon cancer (cancers hadare serious diseases health involving complications uncontrolled from celltoxoplasmo growth)- (now the Democratic Republic of Congo), flew home usually characterized by flat, purple lesions. Some to Denmark. “I’d better go home to die,” Rask told a with healthy immune systems. Others died of pneu- sis, a parasitic infection that seldom affects those andfriend, her matter-of-factly. symptoms had For become over a so year, severe she hadthat been she suffering from unexplained fatigue and weight loss, - mocyctis pneumonia, similar to Grethe Rask. These- had difficulty breathing. Upon arrival in Denmark, puzzling infections would later be identified as op portunistic infections, arising from the immunode aRask progressive was given lung a battery disease of of tests unknown that revealed origin. Hershe Despite the rising death toll from these oppor- was severely immunodeficient and suffering from ficiency caused by HIV/AIDS. USAD Science Resource Guide • 2017–2018 • Revised Page 25 2. Cryptococcal meningitis

protective membranes covering: Meningitis the brain is and an inflammation of the meninges, that is, the- gal infection caused by breathing in the small sporesspinal cord. of Cryptococcus Cryptococcal meningitis is a fun - imately 1 million new, acases fungus of found cryptococ in soil- throughout the world. Worldwide, approx

cal meningitis occur each year, resulting in- 625,000 deaths. HIV infection is the leading risk factor for cryptococcal meningitis, ac ofcounting cases in for high-income nearly 95 percent countries. of cases in low Kaposi’s sarcoma, a cancer that causes the and middle-income countries, and 80 percent growth of purple/red patches on the skin and other 3. Kaposi’s sarcoma (KS) cancer that causes the growth of purple/red areas in the body, was one of the first ‘red flags’ that : Kaposi’s sarcoma, a led to the uncovering of the HIV epidemic.

uncoveringpatches on skinof the and HIV other epidemic. areas inIn thethe body,early in persons with severely weakened immune was one of the first ‘red flags’ that led to the plasmosis may develop however, especially - and other organs. dreds1980s, ofphysicians healthy youngin Los menAngeles, falling New ill York,with systems, causing damage to the eyes, brain, aand rare San cancer Francisco that werewas generallystartled to only see hunseen Treatment and Prevention These physicians noted that most of the men HIV Testing among elderly men of Mediterranean descent. were homosexual and all were immunosup- Diagnosis

HIV—whichpressed, leading weakened them to the conclude immune that system there In order to diagnose someone with HIV, certain andwas was some spread pathogen—later through sexual identifiedcontact. as urine to check for the virus or other signs of infec- tests may be performed on their blood, saliva, or 4. Pneumocystis Pneumonia (PCP) - minutes to see results; these tests usually are fol- cystis pneumonia is an infection of the lungs tion. Rapid screening tests take as little as thirty caused by the fungus Pneumocystis :jirovecii Pneumo. It is extremely rare in people with functioning lowed by a more reliable test to confirm the results. - Three1. Antibodymain types tests of HIV tests are available: - dividuals who are immunocompromised. Be- immune systems, but can be fatal among in produce certain: proteinsWhen you’re called exposed antibodies to vi ruseswhich and help bacteria, neutralize your the immune invading system pathogen. may people.fore the availabilityThis proportion of treatment has dropped for HIV, subPCP- Antibody tests check for the existence of HIV, stantiallyoccurred inover 70 the to past80 percent decade of with HIV-positive the intro- duction of effective medications that protect the immune system against HIV. antibodies, which can be found in the blood or- 5. Toxoplasmosis salivatibody oftests. an infected person. Most HIV tests, including many rapid screening tests, are an caused by the ingestion of the parasite Toxo- 2. Combination or fourth-generation tests plasma gondii : Toxoplasmosis is a disease- As you may remember from the previous sec- : , which can be found in con- taminated soil, cat feces, and undercooked or leavingtion, certain behind immune parts cellsof the (macrophages) pathogen called can symptomsraw meat. orIn nogeneral, symptoms people at all.who Severe are infect toxo- antigens.swallow upThese and antigens digest invading are what pathogens, stimulate ed with this disease experience mild flu-like USAD Science Resource Guide • 2017–2018 • Revised Page 37 of a disease include sex workers, men who have sex with men (MSM), and people who inject drugs (PWID) Incubation period  – the interval between the receipt of the infectious agent and the onset of clinical disease Koch, Robert (1843–1910) – known as the father of modern bacteriology, Koch designed experiments Indoor Residual Spraying (IRS) – the application of that demonstrated that that the bacterium Bacillus insecticides indoors, on walls and other surfaces where anthracis was the cause of anthrax the mosquitoes rest from their feasting; the insecticide kills the mosquitoes when they come in contact with L (large) protein – a viral protein responsible for generating these surfaces a complementary RNA strand for the single strand of RNA contained within an Ebola virion Infectious diseases  – microbial diseases that are transmitted between individuals within a population Latent period – a dormant period of time after infection by certain microorganisms when no symptoms or Infectivity – a pathogen’s ability to cause an infection in transmission to other hosts occurs a susceptible host Lentivirus  – a virus characterized by a long incubation Innate immunity – the non-specific defense response period; HIV is a lentivirus. to antigens entering the body; these antigens may be microbial or non-living. Lymphatic system  – the network of tissues and organs that helps our bodies fight infections and get rid Insecticides – chemicals that repel and kill mosquitos as of waste materials; immune cells typically travel well as other insects. throughout the body via the lymphatic system. Insecticide-treated mosquito nets (ITNs) – mosquito Lymphocyte – a type of white blood cell whose main nets, a thin mesh with holes too small for mosquitoes purpose is to identify an invading pathogen and to pass through, that are treated with insecticides to stimulate the body for an appropriate immune Integrase – the enzyme responsible for integrating viral response; there are two main types of lymphocytes: DNA into the host cell’s DNA B-lymphocytes and T-lymphocytes; B-lymphocytes produce antibodies, and T-lymphocytes attack and Integrase strand transfer inhibitors (INSTIs)  – the kill cells in the body that have already been infected. type of antiretroviral medication that blocks integrase Macrophages – white blood cells that engulf and digest Intermittent preventive treatment (IPT) – the pathogens and other antigens in the body administration of a dose of an antimalarial drug to certain populations at distinct time intervals in Macropinocytosis – a process through which the Ebola order to prevent transmission without substantially virion is swiftly engulfed by the cell membrane of the increasing the probability of drug resistance; people host cell who are especially vulnerable to severe disease, Major histocompatibility complex (MHC) – cell surface including pregnant women, infants, and children, are proteins whose role is to display foreign antigens often the recipients of IPT. to a host’s immune system in order to stimulate an Intracellular pathogens  – pathogens that are able to immune response; the MHC also plays a role in “self” grow and reproduce within eukaryotic host cells recognition, so a host’s immune response does not attack uninfected cells. Jenner, Edward (1749–1823) – the English physician credited with the discovery of the first vaccine; in 1796, Malaria – a vector-borne disease caused by Plasmodium through an experiment with a young boy, he showed parasites; symptoms of malaria often include high that inoculation with cowpox provided immunity to fever and flu-like illness, such as shaking chills, smallpox headaches, muscle aches, and fatigue; malaria can be fatal if untreated. Kaposi’s sarcoma (KS) – an HIV-related cancer that causes the growth of purple/red patches on the skin Mass drug administration (MDA)  – strategy to and other areas in the body eliminate the malaria parasite in a population by distributing antimalarials to everyone, regardless of Key affected populations (KAPs) – marginalized the presence of symptoms and without first testing for populations at higher risk of HIV infection; these infection; this approach is not recommended because

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