Opportunistic infections are conditions caused by microbes which normally do not significantly affect the health of healthy adults but could lead to illnesses in immunocompromised persons like people living with HIV. Generally speaking, the lower the CD4 count, the higher the chance of suffering from various opportunistic infections. No vaccine is available for their prevention. Prophylaxis (medical means of prevention) is indicated in some conditions. In all circumstances, antiretroviral treatment is the best means of achieving immune recovery and recurrence of the opportunistic infection.
Pneumocystis pneumonia (PCP)
Commonest opportunistic fungal infection that often occurs as the first infection alerting HIV patient of the underlying immunodeficiency. Pneumonia is the common clinical presentation. The risk of infection is low when one's CD4 improves after antiretroviral treatment.
Treatment: Anti-microbial medicine treatment; may need steroid
Prophylaxis: Co-trimoxazole (Septrin) may be used for prophylaxis if the CD4 count is below 200/μL
Tuberculosis (TB)
>A very common respiratory infection in Hong Kong. HIV patients may have atypical presentation because of the underlying immunodeficiency. Reactivation disease may occur because of the poor immune defence.
Treatment: Treatment involves the use of multiple antibiotics for extended duration.
Prophylaxis: To prevent reactivation, patient with latent infection requires a course of antibiotics for up to nine months. Latent TB is diagnosed by a skin test or a special blood test called IGRA.
Fungal infections
Systemic fungal infections are uncommon in healthy adults but could cause severe disease in people living with HIV. The ones commonly seen in Hong Kong include Talaromyces, Candida, Cryptococcus. Their occurrence implies that the immunity is severely destroyed because of late diagnosis of HIV infection, or failure to received antiretroviral treatment.
Treatment: Anti-fungal treatment
Prophylaxis: Anti-fungals may need to be continued after completing treatment, as a means of preventing recurrence.
Non-tuberculous Mycobacterial infection
This is an uncommon condition in otherwise immunocompetent persons. Like fungal infection, its occurrence signifies poor immunity.
Treatment: Anti-mycobacterial treatment over prolonged period.
Prophylaxis: Early initiation of antiretroviral treatment is the best strategy for preventing its occurrence.
Cytomegalovirus (CMV) infection
This is a mild viral infection in healthy people but may cause severe diseases with blindness in people living with HIV.
Treatment: Antiviral treatment targeting CMV is needed.
Prophylaxis: Antiviral prophylaxis may be needed to prevent recurrence.
Toxoplasmosis
Toxoplasma is a protozoa that can cause brain disease when one's CD4 count is low at below 50/μL. Common sources of this organism include cats or birds, undercooked meat.
Treatment: Antimicrobial medicines.
Prophylaxis: PCP prophylaxis is also effective in preventing from toxoplasmosis.
JC virus
JC virus causes a complex brain condition called Progressive Multifocal Leukoencephalopathy (PML)
Treatment: Treatment is difficult.
Prophylaxis: No vaccine or preventive medicine is available.