Differentials
Pneumonia
SIGNS / SYMPTOMS
Common infectious aetiologies of pulmonary disorders in patients with HIV/AIDS in the current era include typical bacterial pneumonia (especially pneumococcus), atypical and viral pneumonia, Pneumocystis jirovecii pneumonia, and tuberculosis. Less common causes include endemic fungal infections (e.g., histoplasmosis, coccidiomycosis), staphylococcal pneumonia, and toxoplasma pneumonitis.
INVESTIGATIONS
Chest x-ray or CT, CD4 count, sputum Gram stain and culture, and antigen and molecular tests may be required for definitive diagnosis.
Diarrhoea
SIGNS / SYMPTOMS
Common presentation in people living with HIV with enterocolitis caused by bacteria, including Mycobacterium tuberculosis and Mycobacterium avium complex, parasites, (cryptosporidia, microsporidia, or cystoisosporiasis), or cytomegalovirus. The clinical history including degree of immunosuppression, nature and duration of symptoms, concomitant medicines, travel, and other exposures may help to differentiate the underlying cause.
INVESTIGATIONS
CD4 count, stool GI pathogen PCR panel, stool leukocyte examination, stool culture for enteric bacterial pathogens, ova, and parasites; Clostridium difficile toxin assay; stool examination at least 3 times with modified acid-fast stain (Cryptosporidium, Cyclospora, and Isospora).
Endoscopic evaluation with biopsy.
Meningitis
SIGNS / SYMPTOMS
Toxoplasmosis, cryptococcosis, mycobacterial infection (especially tuberculosis), and progressive multi-focal leukoencephalopathy are the most common opportunistic infections involving the central nervous system. The degree of immunosuppression, the presence of seizures, headache, focal versus non-focal process, and disturbance of cognitive function may be helpful.
INVESTIGATIONS
CD4 count, cerebrospinal fluid (CSF) opening pressure and analysis including cell count, India ink, and acid-fast bacilli stains; CSF polymerase chain reaction, cryptococcal antigen in the CSF and serum; brain CT and MRI.
Hepatitis
SIGNS / SYMPTOMS
Viral hepatitis (hepatitis A virus, hepatitis B virus, hepatitis C virus), Mycobacterium avium complex, tuberculosis, cryptococcus, toxoplasma, may have similar clinical presentation. The clinical history including degree of immunosuppression may help to differentiate the underlying cause.
INVESTIGATIONS
Hepatitis serologies, liver enzyme levels, blood culture for acid-fast bacilli, liver biopsy.
Oesophagitis
SIGNS / SYMPTOMS
The clinical presentation may appear similar to candidiasis, herpes simplex virus, cytomegalovirus, idiopathic oesophageal ulcers, and less commonly Mycobacterium avium complex and tuberculosis. The clinical history (including degree of immunosuppression), inspection of the oropharynx (thrush, ulcers) may be helpful.
INVESTIGATIONS
Endoscopic evaluation with mucosal biopsy; CD4 count.
Retinitis
SIGNS / SYMPTOMS
Causes in people living with HIV include cytomegalovirus, toxoplasmosis, syphilis, herpes simplex virus, or varicella-zoster virus. The clinical history (including degree of immunosuppression), physical findings, including extra-ocular disease, may be helpful.
INVESTIGATIONS
Ophthalmological (fundoscopic examination), CD4 count.
Fever of unknown origin
SIGNS / SYMPTOMS
Tuberculosis and Mycobacterium avium complex, cytomegalovirus, lymphomas, toxoplasmosis, and cryptococcosis often present with fever. History should be thorough, including travel and exposures. Physical examination with emphasis on oral cavity, skin, sinuses, eyes, lungs, lymph nodes, and peri-anal area.
INVESTIGATIONS
CD4 count; blood cultures for acid-fast bacilli; serological tests; respiratory specimen tests; chest x-ray; stool examination; brain imaging (CT or MRI).
Lymphadenopathy
SIGNS / SYMPTOMS
Primary HIV infection, mycobacterial diseases including tuberculosis and Mycobacterium avium complex, herpes simplex virus, cytomegalovirus, cryptococcus, syphilis, toxoplasma, Bartonella henselae, endemic mycoses (coccidioidomycosis and histoplasmosis), and non-Hodgkin's lymphoma can cause generalised lymphadenopathy. Exposures, travel history, medicines, degree of immunodeficiency, and constitutional symptoms are important. The location, size, consistency, fixation (or not), tenderness of lymph nodes, and splenomegaly can help.
INVESTIGATIONS
FBC, chest x-ray, lymph node biopsy for cultures and cytological tests, blood cultures including for acid-fast bacilli.
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