2.4 Clinical presentation in HIV-infected patients


TB is a leading cause of HIV-related morbidity and mortality, and it is one of the main opportunistic diseases13. According to the WHO clinical staging of HIV/AIDS, HIV patients with pulmonary TB are in clinical stage III and HIV patients with extrapulmonary TB are in clinical stage IV14.

In the early stages of HIV infection, when the immune system is functioning relatively normally, the clinical signs of TB are similar to those in HIV-negative individuals.

As the immune system deteriorates in later stages of the disease, the patterns of TB presentation become increasingly atypical, with pulmonary smear-negative, disseminated, and extrapulmonary TB forms becoming more common. These cases are more difficult to diagnose and have a higher fatality rate than smear-positive cases. Algorithms presented in Chapter 4, Section 4.2 use clinical criteria combined with laboratory and other investigations to help diagnose TB in HIV-infected individuals.

HIV patients with PTB tend to experience more fever and weight loss compared to those who are HIV-negative. Yet, these patients suffer with less coughing and haemoptysis due to lesser inflammation and cavity formation. Smear microscopy is more often negative.

Table 2.2 provides a differential diagnosis of PTB in HIV-infected patients.


Table 2.2 - Differential diagnosis for PTB in HIV-infected patients

Diseases

Comments

Other pneumonia
(bacterial, viral, atypical)

  • Bacterial pneumonia (most often S. pneumoniae, H. influenzae) is common at all stages of HIV infection.
  • Atypical pneumonia (M. pneumoniae, C. pneumoniae) and viral pneumonia (respiratory syncytial virus, cytomegalovirus) are possible at any CD4 count, except cytomegalovirus which occurs at CD4 < 50.

Pneumocystosis
(Pneumocystis jirovecii pneumonia or PCP)

  • PCP has many characteristics in common with TB (insidious onset, persistent cough, fever) but tends to occur in the latter stages of HIV infection (CD4 < 200).
  • It imparts a greater degree of dyspnoea, rarely produces effusions, and is not usually accompanied by haemoptysis. For more information, see Diagnostic algorithm 2, Chapter 4.

Pulmonary Kaposi's sarcoma (KS)

  • KS can resemble TB, with slow-onset of cough, fever, haemoptysis, night sweats and weight loss. It is a disease of late-stage HIV, and in most cases, is preceded or accompanied by lesions involving the skin and mucus membranes.

Less common diseases

  • Pulmonary cryptococcosis, histoplasmosis and other fungal infections.
  • Pulmonary nocardiosis: on direct smear, nocardia are weakly acid-fast, similar in appearance to mycobacteria (although they are branching filamentous bacilli, particularly on Gram staining).


In HIV adult patients, the most common non-pulmonary forms of TB are lymphadenopathy, pleural effusion, pericarditis, meningitis, as well as, miliary (disseminated) TB. In HIVinfected children, miliary TB, TB meningitis and diffuse lymphadenopathy are the most common non-pulmonary forms.

PTB is also present in patients with EPTB.

Immune reconstitution inflammatory syndrome (IRIS) is a clinical presentation of TB in patients starting antiretroviral therapy. See Chapter 12, Section 12.7 for clinical presentation and management of IRIS15.