HIV Flashcards
What is the most common opportunistic pathogen in HIV?
HIV patients are vulnerable to pneumocystis jiroveci - yeast-like fungal pathogen that can cause pulmonary infection in patients who are significantly immunocompromised. It is one of the most common opportunistic infections in HIV, occurring in those whose CD4 count <200 cells/mm^3. PCP can also occur in immunocompromised for other reasons e.g. chemo and post-transplant immunosuppression.
What is a late diagnosis of HIV?
- A late diagnosis is defined as a CD4 count <350 cells/mm^3 within 3 months of diagnosis
- Those diagnosed late are likely to have had HIV for >3yrs and are at increased risk of transmitting the infection due to higher viral loads
- Late HIV diagnoses are associated with increased risk of opportunistic infections, increased morbidity and mortality, impaired response to HAART and increased healthcare costs.
- Chronic diarrhoea of unknown cause is an indication for HIV testing
What are high risk groups for HIV?
People from areas of high HIV incidence, IV drug users and sexual behaviours
What is the consent process for HIV testing?
HIV testing requires informed verbal consent and should be documented in patient notes. It is important to be clear if it is a screen due to patient living in a high prevalence area or if HIV is suspected due to an indicator or disease or high risk lifestyle.
Positive tests need repeating, negative tests require no further action unless window period (4 weeks) is suspected.
What is the typical presentation of pneumocystis jiroveci?
Exertional dyspnoea (which progresses over several weeks), malaise and dry cough. Patients may demonstrate a fall in oxygenation between rest and exercise. In many cases, PCP is the first presentation of HIV and the HIV diagnosis is made by the respiratory physicians after investigations show PCP. PCR from sputum or broncho-alveolar lavage (BAL) can also do serum beta-D-glucan and chest imaging.
What is the PCP prophylaxis dose?
Patients infected with HIV who have a CD4 count <200cells/mm^3 are advised to take PCP prophylaxis:
- 1st line: low dose of co-trimoxazole 960mg OD
- 2nd line: Dapsone 50mg OD
- 3rd line: Atovaqone 750mg BD
Who else should be screened for HIV if someone tests positive?
All known sexual contacts with the individual should be offered a test for HIV. This includes current and previous partners. If a woman tests positive then her children should also be tested. The patient and their sexual contacts should also be offered a full STI screen (chlamydia, gonorrhoea, Hep B+C, syphilis). The risk of mother to child transmission is between 15-45% where no measures are taken to reduce the risk of transmission e.g. antiretroviral medication for mother and baby.
How can transmission of HIV be reduced from mother to child?
During pregnancy as long as the virus remains under control the risk to baby is low. At birth the baby can be given antiretrovirals e.g. zidovudine (~4 weeks) and then tested regularly using HIV DNA PCR. Then further testing was carried out at 18 months using an HIV antibody. The mother will be advised to avoid breastfeeding if possible and bottle-feed her baby (even if viral load is undetectable) as there is a small possibility of HIV transmission during breastfeeding.
What can initiation of ART result in?
Immune reconstitution inflammatory syndrome (IRIS) whereby start of ART is often postponed in patients with serious opportunistic infections like PCP, TB or cryptococcal meningitis, as IRIS worsens their outcomes. Resistance can develop quickly if tablets are missed or taken late.
What happens when a person is stable on ART?
With an undetectable viral load, patients are unable to transmit the virus to sexual partners. This is known as U=U in publicity.
What are notifiable diseases?
- Encephalitis/meningitis
- Cholera
- Diphtheria
- Enteric fever (typhoid or paratyphoid fever)
- Food poisoning
- HUS
- Leprosy
- Malaria
- Measles
- Tetanus
- VHF - viral haemorrhagic fever
- Yellow fever
When are PPIs contraindicated?
PPIs must never be used with Rilpivirine as they will reduce the plasma concentration of it and can lead to rapid development of drug resistance. H2 antagonists and antacids also interact with Rilpiviriine, though can be used under certain circumstances. However, they are best avoided if at all possible.
Describe post-exposure prophylaxis (PEP)
When an individual has had an exposure that puts them at risk of acquiring HIV, then they can receive PEP. This is a course of anti-retroviral drugs that will dramatically reduce the risk of someone going on to develop HIV after a high risk exposure. This could apply to individuals who have had a high risk sexual encounter or healthcare workers who may have been exposed to the virus. It is essential that PEP is started within 72 hours of the exposure to be fully effective. All hospitals have a ‘needle stick policy’ that gives guidance on how to approach a possible HIV exposure for healthcare workers.
Describe pre-exposure prophylaxis (PrEP)
Some individuals are identified as high risk for acquiring HIV, such as engaging in certain sexual behaviours or IV drug use. Taking ARDs daily can dramatically decrease risk for contracting HIV. PrEP should only be used alongside other strategies to reduce risky behaviour and under the supervision of a doctor experienced in HIV medicine and using PrEP.
What is an indicator illness?
An illness that can be linked to HIV infection and therefore an HIV test should be offered.
