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HIV, the human immunodeficiency virus, is a virus which infects people for life.
Viruses are extremely small, very simple organisms which can only exist and multiply by invading and taking control of a plant or animal cell (the host cell). Viruses are responsible for many diseases such as influenza and the common cold. Unlike bacteria they are not killed by antibiotics. Viruses may be divided into many different groups. HIV belongs to a group of viruses known as retroviruses.
People infected with HIV are said to be HIV positive.
HIV is the human immunodeficiency virus.
They are a group of viruses which are unique in nature as they have a special enzyme called reverse transcriptase. This enzyme enables HIV to introduce its own genes into the nucleus of the host cell. The host cell is then instructed to produce millions of new copies of the virus. These are released into the bloodstream and can then infect other cells. Retroviruses usually cause long periods of silent infection before signs of disease appear.
HIV is a retrovirus.
HIV causes AIDS (Acquired Immunodeficiency Syndrome). Without treatment with antiretroviral drugs, AIDS is a fatal condition.
HIV causes AIDS.
AIDS is a clinical syndrome which presents in people with advanced HIV infection (severe HIV disease). It can present in many different ways. The symptoms and signs of AIDS are usually due to secondary infections with a number of different organisms not normally seen in HIV-negative people. People with AIDS are always HIV positive.
The terms ‘symptomatic HIV’ or ‘HIV disease’ are also used for patients who are clinically ill because of HIV. These patients may not yet be ill enough to be labelled as having AIDS.
AIDS is a severe illness which presents in people who have advanced HIV infection.
HIV invades and destroys the immune system by damaging the CD4 lymphocytes. As the CD4 cells play a very important role in the functioning of the immune system, HIV infection of CD4 cells damages the immune system, leading to immune deficiency. Therefore, HIV destroys more and more CD4 cells, and the body’s immune system becomes weaker and weaker.
The normal immune system protects the body against infection. Therefore, by killing CD4 cells, HIV weakens the immune system which is then no longer able to prevent infection by many viruses, bacteria, fungi and parasites.
HIV infection damages the immune system.
Two types of HIV are recognised, HIV1 and HIV2. Most HIV infection in southern Africa is caused by HIV1, which has many subtypes (clades). The important subtype in Africa is subtype C. Subtype B is the most common subtype in the developed world.
Yes. HIV infection can be spread from one person to another.
The virus may be transmitted from one person to another by:
There is no evidence that HIV can be spread by mosquitoes, lice or bed bugs. In Africa, HIV is most commonly spread by heterosexual intercourse.
HIV is almost always transmitted by penetrative sexual intercourse (heterosexual or homosexual). However, all forms of oral sexual contact (mouth to vagina or mouth to penis) can also result in infection, although the risk is less. Deep kissing rarely transmits HIV, unless mouth ulcers are present. HIV cannot penetrate intact skin but may infect through open sores, cuts and abrasions, or mucous membranes. Circumcision offers some protection against acquiring HIV infection, i.e. infection is more common in uncircumcised men than circumcised men. The highest risk of sexual transmission for both men and women is during anal intercourse. The thin, friable rectal mucosa is easily damaged during anal intercourse, which increases the risk of infection. The presence of any other sexually transmitted infection will also increase the risk of HIV infection.
In South Africa, HIV is usually spread by sexual intercourse.
Sexual abuse and rape may also result in HIV infection.
No. Family and friends of an HIV-infected person do not become infected except by sexual contact. HIV is not transmitted by close social contact such as touching, holding hands, hugging and social kissing. HIV is also not spread by coughing, sneezing, swimming pools, toilet seats, sharing cooking, drinking and eating utensils or by changing a nappy. However, any bleeding, such as nose bleeds, may spread HIV.
Through the behavioural change of ‘ABC’:
The reduction in number of sexual partners seems to have resulted in the declining HIV prevalence in some countries. However, all three behavioural changes are important.
Yes. A person is usually infected with HIV for years before becoming ill. Therefore, most people infected with HIV are clinically well (asymptomatic) for many years.
Yes. HIV is frequently transmitted by people who appear to be clinically well but are infected with HIV. This is the great danger of HIV infection as most infected people do not know that they have been infected. They are also unaware that they may transmit HIV to another person.
Over 35 million people worldwide have HIV infection. It was estimated that 6.4 million South Africans were living with HIV in 2012. In 2011, 29.5% of all pregnant women in South Africa were infected with HIV. The province of KwaZulu–Natal had the highest prevalence of 37.4%. In some antenatal clinics, more than 50% of pregnant women were HIV positive.
It is estimated that over 600 people die of HIV infection each day in South Africa. Many of these deaths could be prevented with the correct treatment. Without antiretroviral treatment most people with HIV infection will eventually die of AIDS.
No. The rate of HIV infection in women attending state antenatal care clinics in South Africa has been stable at around 29% from 2007 to 2011. But this is very high and though HIV infections have decreased, in South Africa over one thousand people are still infected with HIV every day.
South Africa has one of the largest HIV epidemics in the world.
The risk of HIV crossing the placenta during pregnancy is 5%, while the risk of HIV infecting the infant during labour and vaginal delivery is 15%. Without HIV prophylaxis with antiretroviral drugs the overall risk during pregnancy, labour and vaginal delivery is therefore 20%.
There is an additional risk of 15% if the mother practises mixed breastfeeding (breast milk plus other liquids and solids) for two years. The total risk of mother-to-child transmission (MTCT) in these breastfed infants is therefore 35%. The risk of breast milk transmission is 5% for the first six months, 5% for the second six months and 5% for the second year. With exclusive breastfeeding (breast milk only) for six months, the risk is much lower.
The most effective method in women with HIV infection is to use antiretroviral drugs prophylactically. The risk of mother-to-child transmission can be reduced to below 2% by:
With the roll-out of the prevention of mother-to-child transmission (PMTCT) programme, the number of HIV-infected children should be greatly reduced.
The use of prophylactic antiretroviral drugs reduces the risk of mother-to-child transmission.
The epidemic of HIV infection has had devastating impact on society in South Africa and other countries in sub-Saharan Africa. At the peak of the AIDS epidemic in South Africa, the average life expectancy fell to around 45 years but has increased to around 60 years following the roll out of ART.
In Africa, most people with HIV infection are female and most are from poor communities. This has a massive effect on families and increases the risk of childhood under-nutrition and death, even in HIV-negative children. As a result of the number of deaths, ill people and homeless children, HIV infection has had an enormous social and financial impact on all communities, and has placed a strain on the health services.
Every effort must be made to prevent women becoming infected with HIV. This is the most effective way of preventing HIV infection in children.
By either detecting antibodies to the virus or identifying part of the virus in the blood.
People must be informed and counselled before blood tests are done to confirm or exclude HIV infection. It should be documented that the person consents to screening. It is considered unethical practice to perform HIV screening tests without the person’s permission. HIV screening is very important as it is the ‘gateway to care’.
A number of tests are available to screen people for HIV infection:
See skills chapter 6A for how to do a rapid test.
These are commonly used blood tests to screen well people for HIV infection and also to confirm HIV infection in people who have symptoms and signs. Both are cheap and very accurate, and become positive if antibodies to HIV are present. These tests do not determine whether the actual virus is present, but rather the body’s response to the HIV infection. Therefore, they are highly reliable but indirect tests for HIV. The rapid test is most commonly used to screen for HIV infection.
The rapid test is the most common method used to screen people for HIV infection.
The ELISA test is done by a laboratory on a sample of venous blood taken from the person. 1 to 2 ml of clotted blood is needed. The laboratory should provide a result within 24 hours. The result is either positive or negative. The disadvantage of the ELISA test is that it cannot be done at a clinic.
The great advantage of the rapid test is that it can be done on a drop of blood in a clinic and blood does not have to be sent to a laboratory. There are a number of manufacturers who provide rapid tests. They are very similar, but not exactly the same. If a rapid test is positive with one kit, it is important to repeat the test with another kit from a different manufacturer to confirm that the person really is HIV positive.
In order to detect false-positive tests (the test is positive but the patient is not infected with HIV), all positive screening tests should be repeated with another kit or with another type of test.
This test determines whether there is DNA from the HIV (genetic material from the nucleus of the virus) present in the lymphocytes in the person’s blood. The PCR test is very useful in screening infants younger than 18 months for HIV infection as the rapid and ELISA tests are unreliable to confirm HIV infection at this time, due to the possible presence of maternal antibodies.
The PCR test detects very small amounts of HIV material in the blood.
P24 antigen is part of the virus. The p24 antigen test detects this HIV material in the blood. The ultrasensitive p24 antigen test is very accurate.
They may become positive as early as two weeks after infection, but most are reliable from six weeks after infection.
This is the period of time between infection and the test becoming positive. During this time the test may give a false-negative result (the patient is infected with HIV but the test is still negative). For most tests, the window period lasts up to six weeks. Rarely, the window period may be longer, up to three months. With new, highly sensitive tests the window period is shortening.
CD4 cells are lymphocytes that play a very important role in the normal functioning of the immune system. HIV attaches to CD4 cells and kills them. As a result, the number of CD4 cells gradually falls as the HIV infection progresses, and more and more CD4 cells are killed. Therefore the CD4 count is the best measure of the degree that HIV has damaged the immune system. The normal CD4 count in a healthy adult is above 500 cells/µl.
The CD4 count measures the degree of damage done by HIV to the immune system.
The viral load is a measure of the amount of HIV in the blood. The higher the viral load, the faster the HIV is multiplying. A high viral load indicates that there is a lot of HIV in the blood (and other body secretions). Viral load is usually expressed as RNA copies/ml.
The viral load is a measure of the amount of HIV in the blood.
HIV infection can be divided into three phases.
In response to infection with HIV, the immune system produces antibodies against the virus. Unfortunately these antibodies fail to kill all the HIV. At the time that HIV antibodies appear in the blood (seroconversion) about 50% of people develop a flu-like illness which lasts a few days or weeks. Acute seroconversion illness presents two to six weeks after infection with HIV.
During acute seroconversion illness the viral load is very high and the CD4 count may be temporarily depressed. The screening tests for HIV may still be negative at the time of acute seroconversion illness, and only becomes positive a few weeks later.
Infection with HIV may cause acute seroconversion illness.
The common features of acute seroconversion illness are:
The above signs and symptoms are similar to those found in glandular fever (infectious mononucleosis).
Acute seroconversion illness is often the first sign of HIV infection.
Yes, during the first few weeks of HIV infection, especially if the person develops seroconversion illness, large amounts of virus are present in the blood and other body fluids, and the person is very infectious to others.
People are very infectious during the first weeks of HIV infection.
The patients are managed symptomatically with antipyretics (e.g. paracetamol) for fever.
HIV infection and seroconversion are followed by a latent period when the person feels well. During this phase many people are not aware that they are HIV infected. Although there are usually no, or few, clinical signs during the latent phase of HIV infection, generalised lymphadenopathy is common.
During the latent phase the viral load is low and the CD4 count is normal or only mildly depressed.
Most people with asymptomatic HIV infection are not aware that they have been infected with HIV.
Usually this silent, asymptomatic period lasts five to ten years in adults but it may last for as long as 15 years before the signs of AIDS appear (‘slow progressors’). Occasionally, HIV-infected people progress rapidly to AIDS (‘fast progressors’).
The asymptomatic latent phase usually lasts five to ten years in adults.
When patients who have been clinically well during the latent (asymptomatic) phase of HIV infection become ill, they are said to have symptomatic HIV infection. The symptoms and signs of symptomatic HIV infection only present when the immune system is no longer able to protect the person from a wide range of viral, bacterial, fungal and parasitic infections (opportunistic infections).
Clinical illness only occurs late in the course of HIV infection.
Once patients develop severe opportunistic infections or malignancies typically associated with HIV infection. This only occurs when the immune system has been severely damaged. Patients who are generally well or only mildly ill with HIV infection do not yet have AIDS.
The level of virus in the blood (viral load) rises very rapidly within weeks of infection due to the extremely high rate of viral multiplication. This temporarily depresses the CD4 count. The production of antibodies increases in response to the HIV infection. Antibodies, together with CD4 cells, attempt to control the amount of virus in the body and the levels of HIV in the blood decreases. Eventually (within six months) a balance is reached between the production and destruction of HIV. This is known as the viral set point.
With the onset of symptomatic HIV infection (constitutional symptoms) the CD4 count falls and the viral load increases and becomes very high with AIDS (opportunistic infections).
The level of virus in the blood is very high soon after infection and again with the development of AIDS.
Figure 1-1: The changes in viral load, CD4 count and clinical features of HIV infection
Often painless, generalised lymphadenopathy in an otherwise healthy person is the first clinical sign of HIV infection.
The progression of early to advanced HIV infection usually follows a recognisable pattern which depends on the degree of damage to the immune system. The progression of HIV infection has been divided into 4 clinical stages by the World Health Organisation (WHO). Patients advance through stages 1 to 4 as their CD4 count falls.
The clinical signs become worse and the CD4 count falls as patients progress from stage 1 to stage 4 HIV infection.
See the WHO staging system for HIV infection in adults and adolescents at the end of this chapter.
Patients with stage 1 HIV infection are well and asymptomatic but almost all have persistent, generalised lymphadenopathy, especially in the neck, axilla and groin. Acute seroconversion illness is also included in stage 1. Therefore, stage 1 starts at the time of infection.
People with stage 1 HIV infection are generally well.
Patients with stage 2 HIV infection have repeated minor problems. Skin rashes and minor mouth problems are very common. Often there is some weight loss (less than 10%) and mild diarrhoea can be a problem. Patients with these early stages of HIV infection can usually continue their daily activity.
Patients with stage 2 HIV infection have repeated minor clinical problems.
Common features are unexplained weight loss (more than 10%), fever, oral candidiasis and diarrhoea. Pulmonary TB and severe bacterial infections indicate stage 3 infection. These patients feel generally unwell and are no longer able to continue with their usual daily activities. Most of these patients will improve if their opportunistic infections are treated.
Pulmonary TB and serious bacterial infections are common in patients with stage 3 HIV infection.
Marked weight loss continues and many patients are bedridden. Severe opportunistic infections such as oesophageal candidiasis, extrapulmonary TB, pneumocystis pneumonia, cryptococcal meningitis and toxoplasmosis are common. Anaemia and malignancies associated with HIV infection are also common. Patients with stage 4 disease are regarded as having AIDS. Response to antiretroviral treatment is usually good. Without treatment many will die within months.
Serious opportunistic infections are common when stage 4 HIV infection (AIDS) is reached.
Additional opportunistic infections such as CMV retinitis and avium TB can occur. Severe wasting and dementia are common. These patients are seriously ill, usually with a CD4 count below 50 cells/µl. Response to antiretroviral treatment may be poor as the immune system has been very seriously damaged by HIV. Without treatment most patients rapidly die.
A serious clinical condition which is very uncommon in HIV-negative people and yet seen commonly in patients with advanced HIV infection. Severe opportunistic infections and malignancies in HIV-positive patients are AIDS-defining illnesses. Common AIDS-defining infections include oesophageal candidiasis, and infections with pneumocystis, cryptococcus and toxoplasmosis.
Although pulmonary TB is common in patients with HIV infection, and indicates stage 3, it also occurs in HIV-negative people and it is therefore not an AIDS-defining infection. In contrast, extrapulmonary TB is rare in HIV-negative people and is therefore an AIDS-defining illness.
The mouth and tongue are commonly affected when the immune system is damaged by HIV infection.
Severe oral infections which prevent the patient eating and drinking, and do not improve in a few days, may lead to further weight loss, dehydration and under-nutrition. These patients should be referred to a special HIV clinic.
Many different skin rashes are seen in HIV-infected patients and a skin rash may be one of the earliest signs of a depressed immune system:
Rashes may also be due to drugs used in antiretroviral treatment (e.g. nevirapine) or drugs used to treat opportunistic infections (e.g. co-trimoxazole). Drug reactions are more common in HIV-infected patients than in people who are not HIV infected.
Rashes are often severe, chronic or recurrent, and respond poorly to standard treatment. Rashes frequently are atypical and usually do not resolve spontaneously. Previous rashes may become worse with the development of HIV infection, e.g. psoriasis, acne and eczema. With antiretroviral treatment most rashes disappear.
This is very common in patients with HIV infection and presents with a severe itch and scattered pigmented papules, especially on the trunk and limbs. It is difficult to treat and responds poorly to topical steroids and anti-itch agents.
Before the advent of antiretroviral treatment, this was a common presentation of AIDS in patients in Africa. Weight loss is severe and associated with chronic diarrhoea. The patients feel weak and have fever. All patients with unexplained weight loss must be screened for HIV infection.
All patients with unexplained weight loss must be screened for HIV infection.
Some form of cancer occur more frequently in patients with AIDS. Viral infections and a damaged immune system are probably the cause. Of interest is that only some cancers are more common in AIDS patients. However, the progression of other cancers common in the general population is more rapid in AIDS patients. Cancers more common in patients with AIDS are:
Patients with any of these cancers must be tested for HIV infection.
Kaposi’s sarcoma, non-Hodgkin’s lymphoma and cervical cancer are more common in patients with AIDS.
This is the most common cancer complicating AIDS.
Kaposi’s sarcoma usually presents with multiple pink or purple patches in pale skins and brown or black patches in dark skins, or nodules (bumps) on the skin, especially the face, trunk and legs. The mouth may also be involved, especially the hard palate. The prognosis is poor in advanced cases when organs such as the gut, lungs and lymph nodes are affected (visceral Kaposi’s sarcoma). Non-visceral (skin) Kaposi’s sarcoma is usually not life-threatening, but can become extensive and have an unacceptable appearance. The patches and nodules often improve with antiretroviral treatment. All patients with Kaposi’s sarcoma should start ART within one week of presenting to the clinic. Mild cutaneous KS may respond to ART alone while extensive KS requires chemo or radiotherapy. All patients with extensive skin lesions, oral lesions or signs of disseminated KS should be referred to a KS or specialist clinic within 2 weeks of starting ART.
Kaposi’s sarcoma presents with purple or brown skin patches or nodules.
This is the second commonest cancer in AIDS patients. Non-Hodgkin’s lymphoma is a group of different types of lymphoma which often progress rapidly. Therefore, early diagnosis and treatment are important. Lymphoma usually presents with large firm lymph nodes at one or more sites, or abdominal masses together with weight loss and unexplained fever. Sites other than lymph nodes can be involved, especially the brain, liver, bone marrow and gut. Non-Hodgkin’s lymphoma of the brain may present with a wide range of neurological conditions including headaches, convulsions, confusion and memory loss. Any patient with a suspected lymphoma must be referred for investigation. The prognosis is usually poor.
Lymphoma of the brain may present in AIDS patients with a wide range of neurological signs.
Cervical cancer is common in women with AIDS. In the early stages there are usually no symptoms or signs. Therefore all HIV-positive women must have an annual screen with a PAP smear or cervical inspection for cancer.
All HIV-positive women must be screened regularly for cervical cancer.
Many neurological complications are seen in patients with AIDS. Neurological problems may also be due to drug side effects (e.g. peripheral neuropathy with isoniazid (INH)).
HIV infects the brain early in the course of HIV disease. Signs of HIV encephalopathy usually develop slowly and become more obvious when the patient has AIDS, especially in the advanced stage. Common signs of HIV encephalopathy are:
Often there are no obvious abnormalities on examination of the central nervous system early in the disease. The worsening of HIV encephalopathy can be slowed with antiretroviral treatment.
A healthy pregnant woman is found to be HIV positive. She asks how she probably became infected and whether HIV infection is common in pregnant women. She asks the nurse whether she will pass HIV on to her infant.
By penetrative heterosexual vaginal intercourse. The risk of HIV transmission is highest with anal intercourse in both men and women. The risk of HIV infection is much less with oral sexual contact. Kissing is probably safe.
No. HIV is not spread by touching, holding hands, hugging, coughing, sneezing, using swimming pools, toilet seats or sharing cooking, drinking and eating utensils.
Many people feel well without any clinical signs in spite of having asymptomatic HIV infection for many years.
Yes. The danger is that many infectious people who feel well do not know that they have HIV infection.
In 2011, almost 30% of pregnant women attending state antenatal clinics were HIV positive. This has increased from less than 2% in 1990.
With a vaginal delivery and no antiretroviral prophylaxis, the risk of HIV transmission is 20%. The additional risk of mixed breastfeeding is 15%. With antiretroviral prophylaxis consisting of triple therapy for the mother during pregnancy and breast feeding and Nevirapine for the child during breast feeding the overall risk is less than 2%.
A young woman presents with fever, a sore throat, enlarged lymph nodes and a rash. She also feels generally unwell.
The presentation is typical of the acute seroconversion illness which occurs in 50% of HIV infected people. This condition usually presents two to six weeks after HIV infection and may be misdiagnosed as glandular fever.
No. While treatment may be an option in the future, currently patients are not usually treated during seroconversion except in the context of a clinical trial. Usually symptomatic treatment (e.g. paracetamol for fever) is all that is needed.
By finding a positive screening test (usually a rapid test). The rapid test can be done in a primary-care clinic. A negative test may be repeated after two weeks if acute seroconversion illness is suspected. All patients must be informed and counselled and give consent before a rapid test is done.
The period between HIV infection and a screening test becoming positive. In the window period the HIV blood test may be falsely negative (the test is negative but the person is infected with HIV). The window period usually lasts up to six weeks. Some people with acute seroconversion illness may still be in the window period.
By killing CD4 cells and, thereby, damaging the immune system. As a result the body is unable to protect itself from a wide range of viral, bacterial, fungal and parasitic infections.
The HIV epidemic is having a devastating effect on society. It is estimated that over six million South Africans are HIV positive. Most are female.
A 25-year-old man is seen at a primary-care clinic with herpes zoster which is very painful. He has also lost some weight and complains of recurrent mouth ulcers. On examination he has generalised lymphadenopathy and typical pruritic papular eruption. His HIV test was positive four years ago when he was screened at work. He is still able to continue working.
He should be graded as stage 2. Herpes zoster, recurrent aphthous mouth ulcers and skin rashes with mild weight loss are seen in stage 2 HIV infection. The rapid test confirms the clinical diagnosis. Patients in stage 2 can usually continue working.
Pruritic papular eruption (PPE or ‘itchy bump disease’) is common in patients with symptomatic HIV infection. It presents with scattered pigmented papules (bumps) which are very itchy. The rash is usually seen on the trunk and limbs, it is difficult to treat and responds poorly to topical steroids but usually resolves completely after a few months of ART.
Seborrhoeic dermatitis, molluscum contagiosum, warts, scabies and psoriasis. Bacterial and fungal infections are also very common.
A painful mouth is a common complaint in patients with HIV infection. Recurrent aphthous ulcers, oral candidiasis, herpes ulcers and infected gums are frequently seen. Kaposi’s sarcoma and oral hairy leucoplakia are usually not painful.
This varies between people. However, many people with HIV infection remain well (asymptomatic) for about ten years (except for possible acute seroconversion illness) before developing clinical signs and symptoms of HIV infection.
A woman presents with a cough and night sweats for six weeks and a number of painless, purple patches on her skin. She has oral thrush and difficulty swallowing. Her husband died of AIDS the year before. On testing she is HIV positive.
She almost certainly has pulmonary tuberculosis.
Kaposi’s sarcoma. These patients may have multiple purple or brown skin patches or nodules. The mouth, lymph nodes, lungs and gut may also be involved.
The finding of oral thrush (oral candidiasis) and difficulty swallowing suggests that she may have oesophageal candidiasis.
Yes. Both Kaposi’s sarcoma and oesophageal candidiasis are AIDS-defining conditions as they are very rare in people with a normal immune system (i.e. they are opportunistic infections). She would therefore be graded as having stage 4 HIV infection – i.e. AIDS.
No. If she only had pulmonary TB as a complication of being HIV infected she would be graded as stage 3. Extrapulmonary TB would make her stage 4.
Malignancies associated with AIDS are Kaposi’s sarcoma, non-Hodgkin’s lymphoma and cervical cancer.