IMMUNODEFICIENCY ACQUIRED SYNDROME ((HIV infection, AIDS
Dr. Rasha Salama
PhD. Community Medicine Suez Canal University Egypt
Globally, AIDS caused an estimated 3.1 million deaths in 2003 (2.53.5 million) The epidemic has continued growing, with estimates of 5 million new infections (4.2 5.8 million) and 2.5 million children (2.12.9 million) living with HIV/AIDS.
Identification
Emergence was in 1981 of a cluster of diseases associated with loss of cellular immunity in adults who had no obvious reason for presenting such immune deficiencies. Within several weeks to several months after infection with HIV, many persons develop an acute self-limited mononucleosis-like illness lasting for a week or two. They may then be free of clinical signs or symptoms for months or years before other clinical manifestations develop.
AIDS Associated Disease Categories
1. Gastrointestinal: Cause most of illness and death of late AIDS. Symptoms:
Diarrhea Wasting (extreme weight loss) Abdominal pain Infections of the mouth and esophagus.
Pathogens: Candida albicans, cytomegalovirus, Microsporidia, and Cryptosporidia.
AIDS Associated Disease Categories
2. Respiratory: 70% of AIDS patients develop serious respiratory problems. Partial list of respiratory problems associated with AIDS:
Bronchitis Pneumonia Tuberculosis Lung cancer Sinusitis Pneumonitis
AIDS Associated Disease Categories
3. Neurological: Opportunistic diseases and tumors of central nervous system. Symptoms many include: Headaches, peripheral nerve problems, and AIDS dementia complex (Memory loss, motor problems, difficulty concentration, and paralysis).
AIDS Associated Disease Categories
4. Skin Disorders: 90% of AIDS patients develop skin or mucous membrane disorders.
Kaposi's sarcoma
1/3 male AIDS patients develop KS Most common type of cancer in AIDS patients
Herpes zoster (shingles) Herpes simplex Thrush Invasive cervical carcinoma
5. Eye Infections: 50-75% patients develop eye conditions.
CMV retinitis Conjunctivitis Dry eye syndrome
Extensive tumor lesions of Kaposis's sarcoma in AIDS patient. Source: AIDS, 1997
Infectious agent
Human immunodeficiency virus (HIV), Retrovirus. Two serologically and geographically distinct types with similar epidemiological characteristics, HIV-1 and HIV-2, have been identified. The pathogenicity of HIV-2 may be lower than that of HIV-1 lower rates of mother-to-child transmission for HIV-2.
Structure of the Human Immunodeficiency Virus HIV is a Retrovirus
Occurrence
AIDS was first recognized as a distinct clinical entity in 1981;, however, isolated cases appear to have occurred during the 1970s and even earlier in several areas (Africa, Europe, Haiti, USA). Of the estimated 40 million persons (3446 million) living with HIV infection or AIDS (HIV/AIDS) worldwide in 2003, the largest elements were estimated at 2528.2 million in sub-Saharan Africa, 4.68.2 million in south and southeastern Asia, 13 1.9 million in Latin America and 800 0001 million in North America.
People Living with HIV/AIDS by End of 2001
Western Europe 560,000 East Europe & Central Asia 1'000,000 East Asia & Pacific 1'000,000
North America 950,000
Caribbean 420,000 North Africa & Middle East 500,000 South/South East Asia 5.6 million Latin America 1.5 million Sub-Saharan Africa 28.5 million Australia & New Zealand 15,000
Total: 40 million people
HIV-1 is the most prevalent HIV type throughout the world; HIV-2 has been found in Africa
Reservoir
Humans. HIV is thought to have recently evolved from chimpanzee viruses.
Mode of transmission
Person to person transmission through unprotected (heterosexual or homosexual) intercourse; Contact of abraded skin or mucosa with body secretions such as blood, CSF or semen; The use of HIV-contaminated needles and syringes, including sharing by intravenous drug users; transfusion of infected blood or its components
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Transplantation of HIV-infected tissues or organs. The presence of a concurrent sexually transmitted disease, especially an ulcerative one, can facilitate HIV transmission. Unprotected intercourse (no condom-- unprotected sex) with many concurrent or overlapping sexual partners.
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HIV can be transmitted from mother to child (MTCT or vertical transmission).
From 15% to 35% of infants born to HIV-positive mothers are infected through placental processes at birth. HIV-infected women can transmit infection to their infants through breastfeeding and this can account for up to half of mother-to-child HIV transmission. Giving pregnant women antiretrovirals such as zidovudine results in a marked reduction of MTCT.
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After direct exposure of health care workers to HIV-infected blood through injury with needles and other sharp objects, the rate of seroconversion is less than 0.5%, much lower than the risk of hepatitis B virus infection after similar exposures (about 25%). Unsafe injections may account for up to 5% of transmission.
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While the virus has occasionally been found in saliva, tears, urine and bronchial secretions, transmission after contact with these secretions has not been reported. No laboratory or epidemiological evidence suggests that biting insects have transmitted HIV infection.
HIV Transmission in United States and Rest of the World
Drugs Against HIV
Reverse Transcriptase Inhibitors: Competitive enzyme inhibitors. Example: AZT, ddI, ddC. Protease Inhibitors: Inhibit the viral proteases. Prevent viral maturation. Problem with individual drug treatments: Resistance. Drug combinations: A combination of:
One or two reverse transcriptase inhibitors One or two protease inhibitors.
Drug cocktails have been very effective in suppressing HIV replication and prolonging the of life HIV infected individuals, but long term effectiveness is not clear.
Incubation period
Variable. Although the time from infection to the development of detectable antibodies is generally 13 months, the time from HIV infection to diagnosis of AIDS has an observed range of less than 1 year to 15 years or longer. The median incubation period in infected infants is shorter than in adults.
Period of Communicability
Not known precisely; begins early after onset of HIV infection and presumably extends throughout life. Infectivity during the first months is considered to be high; it increases with viral load, with worsening clinical status and with the presence of other STIs.
Susceptibility
The presence of other STIs, especially if ulcerative, increases susceptibility, as may the fact of not being circumcised for males, a factor possibly related to the general level of penile hygiene.
Interactions between HIV and other infectious disease agents
Mycobacterium tuberculosis infection:
Persons with latent tuberculous infection who are also infected with HIV develop clinical tuberculosis at an increased rate, with a lifetime risk of developing tuberculosis that is multiplied by a factor of 68. This interaction has resulted in a parallel pandemic of tuberculosis. in some urban sub-Saharan African populations where 10%15% of the adult population have dual infection (Mycobacterium tuberculosis and HIV),
Other adverse interactions with HIV infection include pneumococcal infection, non-Typhi salmonellosis, falciparum malaria and visceral leishmaniasis.
Methods of control
A. Preventive measures: HIV/AIDS prevention programs can be effective only with full community and political commitment to change and/or reduce high HIV-risk behaviours.
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Public and school health education must stress that having multiple and especially concurrent and/or overlapping sexual partners or sharing drug paraphernalia both increase the risk of HIV infection.
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The only absolutely sure way to avoid infection through sex is to abstain from sexual intercourse or to engage in mutually monogamous sexual intercourse only with someone known. In other situations, latex condoms must be used correctly every time a person has sexual intercourse.
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Expansion of facilities for treating drug users reduces HIV transmission. HIV testing and counselling is an important intervention for raising awareness of HIV status, promoting behavioural change and diagnosing HIV infection. HIV testing and counselling can be undertaken for:
a) persons who are ill or involved in high-risk behaviours, b) attenders at antenatal clinics, to diagnose maternal infection and prevent vertical transmission; c) couple counselling (marital or premarital); d) anonymous and/or confidential HIV counselling and testing for the "worried well".
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All pregnant women must be counselled about HIV early in pregnancy and encouraged to undertake an HIV test as a routine part of standard antenatal care. Those found to be HIV-positive take a course of ARV treatment, to reduce the risk of their infant being infected.
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All donated units of blood must be tested for HIV antibody; only donations testing negative can be used. People who have engaged in behaviours that place them at increased risk of HIV infection should not donate plasma, blood, organs for transplantation, tissue or cells (...