Micro - 4th Asessment - Hiv And Aids - 3 Feb 2007

HUMAN IMMUNODEFICIENCY VIRUS (HIV) Fourth Medical, 2007 Prof. Widad Al-Nakib, FRCPath.

HIV • HIV (human immunodeficiency virus) infection has now spread to every country in the world and has infected over 40 million people worldwide. About 5 million people get infected with HIV each year and about 3 million people die each year of HIV/AIDS related complications. • By 2000, cumulative deaths due to HIV/AIDS estimated to be 22 million • The scourge of HIV has been particularly devastating in Sub-Saharan Africa • The proportion of adult women among those infected with HIV is increasing

HIV contd. • HIV: A lentivirus of a subgroup of retroviruses • HIV 1 and 2 causes AIDS • The virus kills or damages cells of the body’s immune system • HIV progressively destroys the body’s ability to fight infections and certain cancers • People diagnosed with AIDS may develop lifethreatening diseases from viruses or bacteria that rarely make healthy people sick • These infections are called opportunistic infections.

HIV: Two Types Recognized HIV-1

HIV-2

Both transmitted through sexual contact, blood, from mother to child, and cause indistinguishable AIDS Predominant virus Less easily transmittable Due to high rate of Period between initial replication, mutates infection and illness rapidly into subtypes longer than HIV-1

HIV-1 Subtypes 10 genetically distinct subtypes known Major group (Group M) contains subgroups A to J Group O (Outliers) contains distinct group of heterogeneous viruses These subtypes are unevenly distributed throughout the world

HIV-1 Subtype Distribution Subtype B A and D C E F G and H I O

Region found (predominantly) Americas, Japan, Australia, the Caribbean, and Europe Sub-Saharan Africa South Africa and India Central African Republic, Thailand, and other Southeast Asian countries Brazil and Romania Russia and Central Africa Cyprus Cameroon

HIV Particles

HIV Surface View

HIV Structure

HIV Receptor Attachment

HIV Replication Cycle

HIV Life Cycle

HIV Particles Budding out of Cells

HIV contd. • AIDS: Acquired Immunodeficiency Syndrome was first recognized in 1981 in New York City • The epidemic is growing most rapidly among minority populations • The virus was identified in 1983 • A diagnostic blood test was developed in 1985

HIV Contd. • Most commonly, HIV infection is spread by having sex with an infected partner. The virus can enter the body through the lining of the vagina, vulva, penis, rectum, or mouth during sex • Although initially AIDS cases occurred primarily in homosexual males in the United States, more recently, the majority of new cases are in the heterosexual population

HIV Contd. • HIV also spreads through contact with infected blood through a transfusion of contaminated blood or blood components • HIV frequently spreads among injection drug users who share needles or syringes that are contaminated with blood from an infected person • Women can transmit HIV to their babies during pregnancy or birth

HIV Contd. • The virus does not spread through casual contact such as sharing of food, utensils, towels and bedding, swimming pools, telephones, or toilet seats • The virus is also unlikely to be spread by contact with saliva • People who already have a sexually transmitted disease, such as syphilis, genital herpes, chlamydial infection, gonorrhea, or bacterial vaginosis, are more likely to acquire HIV infection during sex with an infected partner

Signs and Symptoms • Many people do not develop symptoms after getting infected with HIV • Some people have a flu-like illness within several days to weeks after exposure to the virus. They complain of fever, headache, tiredness, and enlarged lymph glands in the neck • These symptoms usually disappear on their own within a few weeks

Progression Course of HIV Infection

Progression Course of HIV Infection

Signs and Symptoms Contd. • Following initial infection, infected individuals may have no symptoms. The progression of disease varies widely among individuals.This state may last from a few months to more than 10 years • During this period, the virus continues to multiply actively and infects and kills the cells of the immune system • The immune system allows us to fight against the bacteria, viruses, and other infectious causes • The virus destroys the cells that are the primary infection fighters, called CD4+ or T4 cells

Signs and Symptoms Contd. Once the immune system weakens, a person infected with HIV can develop the following symptoms: • Lack of energy • Weight loss • Frequent fevers and sweats • Persistent or frequent yeast infections • Persistent skin rashes or flaky skin • Short-term memory loss • Mouth, genital, or anal sores from herpes infections.

AIDS • AIDS is the most advanced stage of HIV infection. The definition of AIDS includes all HIV-infected people who have fewer than 200 CD4+ cells per cubic millimetres of blood • The definition also includes 26 conditions that are common in advanced HIV disease but that rarely occur in healthy people • Most of these conditions are infections caused by bacteria, viruses, fungi, parasites, and other organisms • Opportunistic infections are common in people with AIDS. Nearly every organ system is affected. Some of the common symptoms include the following:

Relationship Between Viral Load,CD4 Count and Progression to AIDS

AIDS/Signs and Symptoms • • • • • • • • • • •

Cough and shortness of breath Seizures and lack of coordination Difficult or painful swallowing Mental symptoms such as confusion and forgetfulness Severe and persistent diarrhea Fever Vision loss Nausea, abdominal cramps, and vomiting Weight loss and extreme fatigue Severe headaches with neck stiffness Coma

AIDS/Cancers • People with AIDS are prone to develop various cancers such as Kaposi sarcoma, cervical cancer, and cancers of the immune system known as lymphomas • Kaposi sarcoma causes round, brown, reddish or purple spots that develop in the skin or in the mouth • After the diagnosis of AIDS is made, the average survival time has been estimated to be 2-3 years

Kaposi’s Sarcoma

Kaposi’s Sarcoma on Arm

Kaposi’s Sarcoma Under the Arm

Laboratory Diagnosis • The diagnosis of HIV infection can be made by detecting the presence antibodies in the blood. • These HIV antibodies are not generally seen until 1-3 months following infection. • Early testing is important because it is generally believed that the earlier treatment is started, the better the outcome. Furthermore, high-risk behaviours that could spread the virus to others can be avoided • Antibody tests- enzyme-linked immunoassay (ELISA) and Western blot, are available. • ELISA is the screening test. • Western Blot is the confirmatory test. • Both of these tests can be negative for up to 3 months after the exposure. In this situation, if the suspicion for HIV infection remains high • HIV RNA by PCR and HIV Antigen by ELISA in the bloodvery important to monitor the efficacy of therapy and when antibody may be undetectable.

HIV Treatment Contd.

• Presently, a combination of several drugs called “highly active antiretroviral therapy” (HAART) is used to treat people with HIV. This treatment is not a cure. The virus still persists in various body sites, such as in the lymph glands • Currently, the survival rates for patients who are fully compliant and well managed can be as high as 80-90%. • Antiretroviral will be covered separately later

HIV Treatment Contd. • People infected with HIV are prone to opportunistic infections. Various drugs are available to treat these infectious complications. These drugs include foscarnet sodium (Foscavir) and ganciclovir (Cytovene, Vitrasert) to treat cytomegalovirus eye infection, fluconazole (Diflucan) to treat yeast infections, and trimethoprim and sulfamethoxazole (Trimeth-Sulfa) to treat Pneumocystis carinii pneumonia • Treatments for Kaposi sarcoma or other cancers include radiation, chemotherapy, and injections of alpha-interferon

HIV Prevention • The only way to prevent infection by the virus is to avoid behaviours that put you at risk, such as sharing needles or having unprotected sex. • Many people infected with HIV don't have any symptoms. There is no way to know with certainty whether a sexual partner is infected • Infected individuals should either abstain from having sex or use latex condoms, which may offer partial protection, during oral, anal, or vaginal sex. • Only condoms made of latex should be used. • Only water-based lubricants should be used with latex condoms

HIV Prevention Contd. • The risk of HIV transmission from a pregnant woman to her baby is significantly reduced if the mother takes AZT during pregnancy, labour, and delivery and her baby takes it for the first 6 weeks of life.

Research Research on HIV infection includes the development and testing of HIV vaccines and new therapies for the disease and its associated conditions Currently, 28 HIV vaccines are being tested on humans, and many drugs for HIV- or AIDSassociated infections are either being developed or tested Researchers are also investigating how HIV damages the immune system and are trying to trace how the disease progresses in different people