GLOBAL PREVALENCE OF HIV

An estimated 33 million people are HIV positive worldwide. HIV-1, a retro virus is responsible for most cases world wide. HIV-2, a related virus produces a similar illness with a longer latent period. More than 3 million have acquired immune deficiency syndrome (AIDS). HIV infection is more prevalent among women and children in sub Saharan Africa. In previously healthy homosexual men cases of rare neoplasm, Kaposi’s sarcoma, and pneumocystis carinii pneumonia were reported in the USA during 1981. This epidemic was eventually termed as the acquired immunodeficiency syndrome (AIDS). The association between HIV virus infection and the development of AIDS was established in 1984. The global AIDS pandemic has stimulated unprecedented research on the pathogenesis, management and control of the disease that has expanded.

The world health organization estimates that number of people living with HIV in year 2007 was 33 million. Around 90% are in developing countries unable to afford the expensive medical care required to control the disease progression. WHO reported 2.7 million new HIV infections and 2.0 million deaths due to AIDS in 2007. Sub-Saharan Africa is the most-affected region in the world as measured by HIV/AIDS prevalence rates. An estimated 22 million adults and children are living with HIV in Sub Saharan African, 4.2 million in South and south east Asia, eastern Europe and central Asia 1.5 million, east Asia 740000, Oceania 74000, middle east and north Africa 380000, western and central Europe 730000, Latin America 1.7 million, north America 1.2 million, Caribbean 230000 respectively. The prevalence of disease is more than 96% in low and middle income countries. WHO reports, Over 7400 new HIV infections a day in 2007. The disease has affected about 1000 children under 15 years of age and about 6300 adults aged 15 years and older.

Women comprise 50% of adults estimated to be living with HIV/AIDS worldwide. Young people under the age of 25 years are estimated to account for more than half of all new HIV infections worldwide. The early epidemics of HIV was facilitated by travel and migration and later by female sex workers and their clients, important risk factor for transmission being the intravenous drug use and use of HIV infected blood and blood products. HIV probably originated from rural areas where it had been endemic at low levels but then spread amongst sexually active population in cities, initially in the early 1980’s amongst homosexual men in the developed countries of Europe, North America, and Australia. This series of epidemic was followed by a wave with predominant heterosexual spread in sub Saharan Africa and South America and lately to south East Asia, where the epidemics have been late in developing but are accelerating at an alarming rate.

There is no single AIDS epidemic worldwide. Instead, many regions and countries are experiencing diverse epidemics. The characteristic of HIV disease in each region are determined by many different microbiological, cultural, social and behavioral aspects. As for example, HIV infection in Uganda, where heterosexual transmission is predominant and infection rate is higher in rural areas. HIV infection in many parts of U.S remains rare, being seen amongst homosexual men and intravenous drug users at a highest rate in major cities. The epidemics in Europe, North America, and Australia have been stabilized, although cases contracted heterosexually and through vertical transmission continue to rise. So, far the sub Saharan African has been the hardest hit by HIV epidemic and rapid spread continues in south East Asia. HIV Infection has a profound impact in the economic and demography of a country. The life expectancy of many children’s are affected as a consequences of increasing heterosexual transmission of HIV. The prevalence of HIV is common between age groups 15 to 50 years who are the economically productive age groups in most countries.

HIV - (Human Immunodeficiency Virus)

(HIV) - Human Immunodeficiency Virus belongs to the subfamily of retroviruses which have an RNA genome. HIV has a core consisting of the RNA genome and core protein surrounded by an envelope with high lipid content, rendering it sensitive to organic solvents. HIV gains entry to host cell by binding to the CD4 receptor using the viral surface membrane glycoprotein gp 120. Host target cells of preference, therefore,carry the CD4 molecule which is recognized by the virus, but in addition other cell surface molecules act as receptors and co-receptors for the virus. The RNA viral genome is transcribed to DNA copy by reverse transcriptase enzyme.Then the DNA copy integrates into host cell genome in cell nucleus via integrase enzyme. Following cell activation viral DNA is translated to RNA copies in cytoplasm. Viral peptide chains are translated from cytoplasmic viral RNA. HIV proteinase cleaves functional viral proteins from polypeptides. Virion assembly occurs.Viral release from cell surface by cell lysis.
There is a huge diversity amongst HIVs, which occurs in 2 main types: HIV 1 and HIV 2. Disease caused by HIV 2 is similar to disease caused by HIV 1 but is generally milder, slower to progress and poorly transmitted vertically. HIV 1 is responsible for most of the disease seen world-wide.HIV 1 is divided into several subtypes,and there are atleast five subtypes of HIV 2.
The acquired immune deficiency syndrome (AIDS), caused by the HIV-1 RNA retro virus, is the most common acquired immune deficiency in the United States. AIDS is currently the most common cause of death in black men and women from 25 to 44 years of age.
The acute phase of HIV infection develops within 2- 4 weeks of contracting the virus. It is characterized by fatigue, sore throat and lymphadenopathy, the CD4 counts are normal to low, with an increase in the P24 antigen which is an indicator of disease activity. In approximately 4 -12 weeks (window period) antibodies against gp 120 and other antibodies are not detected. ELISA test which are positive are confirmed by western blot analysis, which detects more than one HIV antibody (eg; p24 and gp41). After the acute phase, patient enters an asymptomatic latent phase, in which the actively proliferating virus is present within the dendritic cells located in the lymph nodes.After an average span of 4- 10 years, patients enter the late phase of the disease, where the CD4 count drops below 400 cells/microlitre, the p24 antigen resurfaces, and opportunistic infection develops. AIDS is a multisystem disorder with the lungs representing the most frequently involved site.
An opportunistic infection or a CD4 count of less than 200 cells/microlitre is sufficient to diagnose AIDS. The average life span from the beginning of infection to death of the patient is 10 years.
HIV infection is confirmed by demonstrating the presence of antibodies to HIV in serum.The enzyme -linked immunosorbent assay (ELISA) test used for detecting antibodies to HIV is simple and cheap and has the advantage of a very low false negative rate so that the infected cases are unlikely to be missed. All the positive results are normally confirmed by the more precise western blot test, which also detects the presence of anti- HIV antibodies.Serial testing may be required following a high risk of exposure to HIV to exclude infection. Following HIV infection the production of detectable antibodies to various components of the virus,including antibody to the gag protein, integrase and reverse transcriptase may not occur for 6-12 weeks and sometimes much longer. Antibody detection test are unhelpful and misleading in neonates who may be infected because of the presence of transplacentally acquired maternal antibody. The polymerase chain reaction (PCR) can be used in this situation to detect the presence of viral genome in the peripheral blood lymphocytes.However, ELISA remains the routine screening test and is used by centers offering same day or rapid testing services.The advantage of knowing that an individual is HIV-seropositive include appropriate medical care and prophylactic measures which will benefit health, prolong life, and avoid infection to others. When an HIV test is negative the patient should be advised to practice safe sex and to abstain from avoidable risk factors, such as sharing needles for intravenous drug use.
There are three possible modes of transmission of HIV; sexual, perinatal, parenteral. Infection with HIV essentially requires exchange of semen, vaginal or other body secretions, milk or blood or blood products infected by virus. The risk of HIV transmission is greatest with vaginal and anal intercourse. The risk of transmission during intercourse is further increased by presence of sexually transmitted disease, such as any genital ulceration.
Perinatal transmission is increasing globally as a direct result of the increase in number of women with HIV infection who are of child bearing age. HIV during parturition on contact with HIV-containing fluids in the vagina accounts for around 80% of vertical transmission. Neonates of HIV infected women have a 13-52% chance of acquiring HIV from the mother. In utero the virus may infect the fetus by crossing the placenta. Intravenous drug users (IVDUs) are at risk of HIV infection as a result of sharing needles, which allows transmission of HIV infected blood from one individual to another. Transmission of HIV among health-care workers following occupational exposure is a rare event, the major risk factor is a needle stick injury with HIV contaminated blood from an infected patient.
PREVENTION MEASURES FOR HIV TRANSMISSION:
SEXUAL - public awareness campaigns for HIV, safe sex practice like avoidance of penetrative intercourse and use of condoms, targeting safe sex methods at sex industry workers, and control of sexually transmitted diseases.
PARENTERAL- Routine screening of blood or blood products for HIV, needle exchange programmes of Intravenous drug users (IVDUs).
PERINATAL - Routine HIV testing at antenatal clinics, avoidance of pregnancy if HIV- seropositive, Anti-retro viral therapy during pregnancy, delivery or postnatally.

Folic acid

Every woman who could become pregnant are recommended 400 micrograms (400 mcg) of synthetic folic acid every day.
The causes of folate deficiency are, due to poor diet or less intake of vegetables as in alcoholics, or increased demand during pregnancy, haemolysis, dyserythropoiesis, malignancy, long term hemodialysis, malabsorption especially in coeliac disease, tropical sprue and certain drugs like phenytion and trimethoprim all causes folate deficiency.
Folate is found in green vegetables, fruits, liver, and is synthesized by gut bacteria. Good sources of folate are, brussels sprouts, fortified breakfast cereals, spinach, asparagus, beetroot, orange, avocado,melon, potatoes, cauliflower, peas, wholemeal bread, dried beans. Liver is the richest source of folate but an alternative source is advised in early pregnancy because of its high vitamin A content. The most serious side-effects of repeated moderate or high doses of retinol are liver damage, hyperostosis and teratogenity.Therefore woman's who are pregnant in developed countries are advised not to take vitamin A supplements.
Body stores folate sufficient for three months, folate is absorbed mainly in the jejunum. Maternal folate deficiency is also linked to neural tube defects in fetus.
Folate is directly involved in DNA and RNA synthesis and it seems that a higher than normal level is required during embryonic development. All women planning a pregnancy are advised to include good source of folate in their diet.
Folic acid ( pteroylglutamic acid) and related compounds are known as folates. The body obtains folate by breakdown of food polyglutamates to monoglutamates in the small intestine, much is destroyed by cooking. Folic acid as such is available only as a medicinal compound. The coenzyme form of this vitamin is tetrahydrofolic acid.
Folic acid deficiency is most commonly seen in pregnancy and alcoholism. Folic deficiency states can result in megaloblastic anemia and neural tube defects (NTDs).
Folic supplemetation is recommended before and during pregnancy.
Neural tube defects (NTDs) are major birth defects of a baby’s brain or vertebrae. Neural tube defect is an Imperfect closure of the neural tube which takes place 3-4 weeks after conception, which results in birth defects like, spina bifida, anenecephaly, and encephalocele. These birth defects can cause lifelong disability or death.
Studies have shown that folic acid reduces recurrence or occurrence of these deformities by about 70 %, but it must be taken prior to and following conception.
About 3,000 pregnancies in the United States are affected by spina bifida or anencephaly each year. Many of these defects could be prevented if all women got enough of the B vitamin folic acid every day starting before they get pregnant.
Anencephaly is one type of the fetal anomaly where the vault of the skull and brain tissue are absent, the cause is due to failure of the closure of cephalic part of neural tube (open neural tube defect). Babies with this defect die before birth (miscarriage) or shortly after birth.
Any woman can have a baby with an NTD. If a woman can get pregnant, she is at risk for having an NTD-affected pregnancy. No one can predict which women will have a pregnancy affected by an NTD. All women are at risk.
The neural tube is a narrow sheath that closes to form the brain and spinal cord of the embryo. As development progresses, the top of the tube becomes the brain and the remainder becomes the spinal cord. This process is usually complete by the 28th day of pregnancy. But if problems occur during this process, the result can be brain disorders called neural tube defects, including spina bifida.
Spina bifida, is characterized by the incomplete development of the brain, spinal cord, and meninges (the protective covering around the brain and spinal cord). It is the most common neural tube defect in the United States affecting 1,500 to 2,000 of the more than 4 million babies born in the country each year.
Most children born with spina bifida live full lives, but they often have lifelong disabilities and need many surgeries. The effects of spina bifida are different from each children all don’t have the same needs. Some children’s problems are much more severe than others.
The neural tube is the tissue of an embryo (a developing baby to the eighth week after conception). Normally, a fetus’s central nervous system develops inside the neural tube. When this tube does not close properly, an encephalocele may result. Either skin or a thin membrane covers the defect
An encephalocele is classified as a neural tube defect. An encephalocele is a rare disorder in which the skull do not close completely, creating a gap through which cerebral spinal fluid, brain tissue and the membrane that covers the brain (the meninges) can protrude into a sac-like formation.
The physical and emotional tolls upon the families affected by birth defects are high. That’s why it’s so important to encourage women to take folic acid every day to help prevent these birth defects.
Folic acid is a B vitamin that the body needs to make healthy new cells. Every woman who could possibly get pregnant are recommended to take 400 micrograms (400 mcg or 0.4 mg) of folic acid daily in a vitamin or in foods that have been enriched with folic acid.
Along with taking a vitamin or eating a cereal that has 100% DV of folic acid, women should always eat a healthy diet that has lots of fresh fruits and vegetables and other healthy foods.
However, how folic acid works to prevent birth defects is unknown. But studies show that folic acid is needed to make healthy new cells. Taking folic acid every day, starting before and during pregnancy, can reduce the risk for these serious birth defects by 50% to 70%.
Most women in the developed and developing countries do not get enough folic acid to help prevent birth defects. The average woman gets less than the amount needed from her diet alone. That’s why all women who can get pregnant are encouraged to take a vitamin with folic acid or eat a serving of fully fortified breakfast cereal each day.
Folic acid might help to prevent some other birth defects, such as cleft lip and palate and some heart defects.
Everyone needs folic acid. But for women who can get pregnant, it is much more important. If a woman has adequate folic acid in her body before she is pregnant, this can help prevent major birth defects of her baby's brain and spine.Women need to take folic acid every day, starting before they are pregnant to help prevent NTDs.