Model Answer
0 min readIntroduction
Human Immunodeficiency Virus (HIV) infection weakens the immune system, making individuals susceptible to a range of opportunistic infections – infections that typically don’t affect people with healthy immune systems. These infections are a major cause of morbidity and mortality in HIV-infected individuals. Early diagnosis and effective management of these infections, alongside antiretroviral therapy (ART), are crucial for improving patient outcomes. Globally, in 2022, 39.0 million people were living with HIV, and 1.3 million died from AIDS-related illnesses (UNAIDS data). This answer will enumerate important parasitic and fungal opportunistic infections, discuss current HIV testing and monitoring strategies, and briefly outline recommended treatment approaches.
Opportunistic Infections in HIV
HIV-infected individuals, particularly those with low CD4 counts, are vulnerable to a variety of opportunistic infections. These can be broadly categorized as parasitic, fungal, bacterial, viral, and mycobacterial.
Parasitic Infections
- Toxoplasmosis: Caused by Toxoplasma gondii, often presenting as cerebral toxoplasmosis in individuals with CD4 counts <200 cells/µL.
- Cryptosporidiosis: Caused by Cryptosporidium parvum, leading to severe diarrhea, especially with CD4 counts <200 cells/µL.
- Isosporiasis: Caused by Isospora belli, also causing chronic diarrhea, similar to cryptosporidiosis.
- Strongyloidiasis: Can cause hyperinfection syndrome in immunocompromised individuals, leading to widespread dissemination.
- Microsporidiosis: Caused by various microsporidian species, resulting in chronic diarrhea and wasting.
Fungal Infections
- Pneumocystis Pneumonia (PCP): Caused by Pneumocystis jirovecii, a leading cause of pneumonia in HIV-infected individuals with CD4 counts <200 cells/µL.
- Candidiasis: Can manifest as oral thrush, esophageal candidiasis, or invasive candidiasis.
- Cryptococcosis: Caused by Cryptococcus neoformans, often presenting as meningitis, particularly with CD4 counts <100 cells/µL.
- Aspergillosis: Invasive aspergillosis can occur, especially in severely immunocompromised patients.
- Histoplasmosis: Disseminated histoplasmosis is common in endemic areas.
HIV Testing Strategies
HIV testing has evolved significantly, with advancements in sensitivity and specificity. Current strategies include:
Types of HIV Tests
| Test Type | Description | Window Period |
|---|---|---|
| Antibody Tests | Detects antibodies to HIV-1 and HIV-2. | 4-12 weeks |
| Antigen/Antibody Combination Tests (4th Generation) | Detects both HIV antibodies and p24 antigen. | 2-6 weeks |
| Nucleic Acid Tests (NAT) | Detects HIV RNA or DNA directly. | 10-33 days |
Testing Algorithms
- Initial Screening: Typically uses a rapid antibody test or a 4th generation antigen/antibody combination test.
- Confirmatory Testing: Positive screening tests are confirmed with a more specific assay, such as an HIV-1/HIV-2 antibody differentiation immunoassay.
- Early Infection Detection: NAT can be used to detect acute HIV infection before antibody development.
Monitoring HIV Infection
Regular monitoring is essential to assess disease progression and treatment effectiveness.
Key Monitoring Parameters
- CD4 Count: Measures the number of CD4+ T cells, indicating the degree of immune suppression.
- Viral Load: Measures the amount of HIV RNA in the blood, reflecting viral replication.
- Resistance Testing: Identifies mutations in the HIV genome that confer resistance to antiretroviral drugs.
Monitoring Frequency
- Newly Diagnosed Patients: CD4 count and viral load should be measured immediately after diagnosis.
- Patients on ART: CD4 count every 3-6 months, viral load every 3-6 months (more frequent initially).
Recommended Treatment
The standard of care for HIV infection is antiretroviral therapy (ART). Current guidelines recommend initiating ART in all HIV-infected individuals, regardless of CD4 count.
ART Regimens
- First-line Regimens: Typically consist of two nucleoside reverse transcriptase inhibitors (NRTIs) plus a third agent from either an integrase strand transfer inhibitor (INSTI), a non-nucleoside reverse transcriptase inhibitor (NNRTI), or a protease inhibitor (PI).
- Examples: Biktarvy (bictegravir/emtricitabine/tenofovir alafenamide), Triumeq (dolutegravir/abacavir/lamivudine).
Conclusion
Opportunistic infections remain a significant challenge in HIV management, but advancements in diagnostic testing and ART have dramatically improved patient outcomes. Early diagnosis, regular monitoring of CD4 counts and viral load, and prompt initiation of ART are crucial for preventing these infections and improving the quality of life for people living with HIV. Continued research into novel prevention strategies and treatment options is essential to ultimately end the HIV epidemic.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.