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HIV: Overview, Testing And Medical Treatment

Discussion in 'Microbiology' started by Ghada Ali youssef, Jan 10, 2017.

  1. Ghada Ali youssef

    Ghada Ali youssef Golden Member

    Dec 29, 2016
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    Human Immunodeficiency Virus (HIV) is becoming increasingly common. Treatment options have advanced and prognosis is much better than in previous decades, however there is still a lot of stigma attached to a diagnosis. The key to good prognosis is early detection – this article is written to describe some key facts about the virus, discuss HIV testing and to display methods of treatment.

    HIV (Human Immunodeficiency Virus) key facts
    HIV is a retrovirus which depletes the number of t-helper (CD4) cells and gradually causes immunosuppression. There are several strains of the virus, but all have the same effect.


    The general course of the disease is such:

    Seroconversion → Asymptomatic period → HIV-related illnesses → AIDS-defining illnesses

    Seroconversion is the period of time in which antibodies to HIV are produced and become detectable after infection with the virus. This generally takes 2-6 weeks, and is often associated with flu-like symptoms.

    HIV-related illnesses include opportunistic infections which occur due to HIV-related immunosuppression (such as thrush) and co-infection with Hepatitis B or C.

    Due to the varying rate of progression there can be a period of many years between infection and development of symptoms. HIV infection, untreated or advanced, becomes defined as AIDS (Acquired Immune Deficiency Syndrome) when the CD4 count falls below 200, or the patient develops one or more ‘AIDS-defining conditions’ in the setting of being infected with HIV. These are conditions which would not generally occur in patients with competent immune systems.
    AIDS-defining illnesses include oesophageal/pulmonary candidiasis, pneumocystis pneumonia, pulmonary/disseminated mycobacteriosis, HIV encephalopathy, invasive cervical carcinoma, lymphoma.
    For full list of illnesses please see reference article (1).

    UK HIV Statistics (2)(3)
    • 1 in 5 people with HIV in the UK are unaware of their status, or undiagnosed
    • 40% of those diagnosed in 2014 had a CD4 count of <350 (late stage infection)
    • 1 in 7 people receiving treatment for HIV are over 55
    • 40% of HIV infections diagnosed in 2014 were as a result of heterosexual sex
    It is advised that HIV testing should be offered to:

    • All patients with a sexually transmitted infection
    • All women undergoing antenatal screening
    • All registering with a GP where prevalence exceeds 1/500
    • Anyone who has had sexual contact with people from countries of high prevalence
    • All sexual partners of known HIV positive individuals
    • Men with a history of sex with other men
    • Intravenous drug users
    • All patients where HIV (including primary infection) enters the differential
    • Clinical indicator diseases: including TB, early dementia, severe dermatology, chronic diarrhoea, weight loss of unknown origin, lymphadenopathy?cause, hepatitis
    HIV testing:
    • Antibody takes between 2 weeks and 3 months to become detectable in blood
    • Most tests are for HIV antibody and p-24 antigen
    • Patients must be consented for a HIV test
    • Result takes 48-72h (Rapid Point of Care test takes 15-40mins)
    • All positive tests need confirming with a second test on a different date
    HIV diagnosis in pregnant women:
    If a pregnant woman is diagnosed with HIV, they may or may not require immediate treatment depending on their CD4 level. If CD4 low – start HAART (highly active anti-retroviral therapy) as soon as possible, if high CD4 count this depends on viral load.
    • If viral load is undetectable at term, the mother can deliver vaginally
    • Avoid breastfeeding, and consider neonate post-exposure prophylaxis (PEP)
    • Risk of vertical transmission if this is followed is <1%
    Post-Exposure Prophylaxis (PEP)
    If a patient attends with an episode of high risk sexual activity they should be considered and counselled for PEP.
    This involves taking anti-retroviral therapy – 3 drugs, for 28 days, within 72hrs of high-risk event. The drugs given are anti-retrovirals, anti-diarrhoeals and anti-nausea medications.

    Quick PEP facts:
    • Works in the ‘window of opportunity’ – it takes 48-72 hrs for HIV infection to become established. Giving PEP in this timeframe can prevent virus multiplying and entering cells.
    • More effective the earlier it is given, not 100% effective!
    • Re-test after 3 months
    Pre-exposure Prophylaxis (PrEP)
    This is not currently available on the NHS, but is important to be aware of. PrEP is a course of anti-retrovirals that are given to a HIV negative person before high risk sexual activity that minimises the risk of transmitting HIV.

    Benefits of early diagnosis
    There are many benefits to early diagnosis. We are moving towards a culture of more routine testing which is aiding this shift to early diagnoses. The main benefit is that prognosis is improved the earlier HAART is commenced. Treatment can be given before a patient is symptomatic which can prevent and delay HIV positive individuals from becoming unwell.
    When diagnosed early, the life expectancy for a person who is HIV positive is better than that for someone with Type 2 diabetes.

    Every diagnosis of HIV needs to be discussed with a sexual health specialist. They often will initiate and guide treatment, and follow the patient up too. For reference, however, we will now go through the modes of treatment and commencement of treatment.

    • Available since 1996, combination of at least 3 different anti-retroviral therapies – some are now available as a single tablet
    • Types of drugs: Non-nucleoside reverse transcriptase inhibitors (NNRTIs), Nucleoside reverse transcriptase inhibitors (NRTIs) protease inhibitors, fusion inhibitors, integrase inhibitors, entry receptors.
    • Unless you’re a specialised bod, you don’t necessarily have to know or understand the mechanism of action of all of these drugs, but if you’re a keen bean, here’s a starter diagram…
    HAART generally consists of 2 NRTIs and one of either a protease inhibitor, NNRT or integrase inhibitor. There are now some single pill combinations.

    When to begin treatment depends mostly on CD4 count and patient wishes. This should be done only with discussion from a sexual health specialist, and is likely to be commenced by them.

    As a general rule:
    • CD4 count > 500: monitored, but not given HAART
    • CD4 count 351 – 500: treated in certain situations
    • CD4 count ≤350: treatment should be commenced (needs urgent discussion with sexual health specialist)
    To commence HAART the patient needs to be ready and committed to treatment, which involves a once-daily regimen initially. The side effects of HAART can be extensive and severe, especially to begin with. Side effects include nausea, vomiting, diarrhoea, hypersensitivity, anaemia, LFT abnormalities, pancreatitis, lactic acidosis and peripheral neuropathy. For treatment to be effective 95% of adherence is needed. If more doses are missed the effectiveness of the treatment drops and the chances of viral resistance and mutation rise.

    Factors that can affect adherence to treatment include unmanageable side-effects, asymptomatic disease, stigma, psychological problems, alcohol or other substance misuse and difficulty storing drugs (requirement for refrigeration).

    Substances that can interact with HAART include: methadone, sedatives, anti-epileptics, some anti-depressants, ecstasy, St John’s Wort, hormonal treatments.

    The response to HAART is measured regularly by viral load and CD4 count. The lower the viral load, the less transmission risk there is.

    (1) Centre for Disease control and Prevention – List of AIDS defining illnesses

    (2) NAT (2016)

    (3) Public Health England (2015) HIV in the UK – Situation Report 2015: Incidence, prevalence and prevention. Accessed


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