HIV related Opportunistic Diseases M.MEIDANI,MPH.MD

In untreated patients or in patients in whom therapy has not adequately controlled virus replication, after a variable period, usually measured in years, the CD4+ T cell count falls below a critical level (<200/µL) and the patient becomes highly susceptible to opportunistic disease .

In countries where ARV therapy and prophylaxis and treatment for opportunistic infections are readily accessible to such patients, survival is increased dramatically even with this level of advanced disease.

In contrast, untreated patients who progress to this severest form of immunodeficiency usually succumb to opportunistic infections or neoplasms

While the causative agents of the secondary infections are characteristically opportunistic organisms such as P. jiroveci, atypical mycobacteria, CMV, and other organisms that do not ordinarily cause disease in the absence of a compromised immune system, they also include common bacterial and mycobacterial pathogens.

Disease of the Respiratory SystemDisease of the Respiratory System

Pulmonary disease is one of the most frequent complications of HIV infection.

The most common manifestation of pulmonary disease is pneumonia.

The two most common causes of pneumonia are bacterial infections and the unicellular fungus P. jiroveci infection.

Other major causes of pulmonary infiltrates include mycobacterial infections, other fungal infections, nonspecific interstitial pneumonitis, KS, and lymphoma.

Disease of the Respiratory SystemDisease of the Respiratory System

Patients with PCP generally present with fever and a cough that is usually nonproductive or productive of only scant amounts of white sputum.

The most common finding on chest x-ray is either a normal film, if the disease is suspected early, or a faint bilateral interstitial infiltrate.

Disease of the Respiratory SystemDisease of the Respiratory System

Arterial blood gases may indicate hypoxemia with a decline in PaO2 and an increase in the arterial-alveolar (a – A) gradient.

A definitive diagnosis of PCP requires demonstration of the organism in samples obtained from induced sputum, bronchoalveolar lavage, transbronchial biopsy, or open lung biopsy.

Disease of the Respiratory SystemDisease of the Respiratory System

The standard treatment for PCP or disseminated pneumocystosis is trimethoprim/sulfamethoxazole (TMP/SMX).

Alternative treatments for mild to moderate PCP include dapsone/trimethoprim and clindamycin/primaquine.

Intravenous pentamidine is the treatment of choice for severe disease in the patient unable to tolerate TMP/SMX.

For patients with a PaO2 < 70 mmHg or with an a – A gradient >35 mmHg, adjunct glucocorticoid therapy should be used in addition to specific antimicrobials.

Overall, treatment should be for 21 days and followed by secondary prophylaxis.

Disease of the Respiratory SystemDisease of the Respiratory System

Worldwide, approximately one-third of all AIDS-related deaths are associated with TB.

In contrast to infection with atypical mycobacteria such as MAC, active TB often develops relatively early in the course of HIV infection and may be an early clinical sign of HIV disease.

In patients with relatively high CD4+ T cell counts, the typical pattern of pulmonary reactivation occurs in which patients present with fever, cough, dyspnea on exertion, weight loss, night sweats, and a chest x-ray revealing cavitary apical disease of the upper lobes.

Disease of the Respiratory SystemDisease of the Respiratory System

In patients with lower CD4+ T cell counts, disseminated disease is more common. In these patients the chest x-ray may reveal diffuse or lower lobe bilateral reticulonodular infiltrates consistent with miliary spread, pleural effusions, and hilar and/or mediastinal adenopathy.

Respiratory isolation and a negative-pressure room should be used for patients in whom a diagnosis of pulmonary TB is being considered.

Disease of the Respiratory SystemDisease of the Respiratory System

Therapy for TB is generally the same in the HIV-infected patient as in the HIV-negative patient.

The most common atypical mycobacterial infection is with M. avium or M. intracellulare species—MAC.

Fungal infections

Diseases of the Cardiovascular Diseases of the Cardiovascular SystemSystem

Pericardial effusions may be seen in the setting of advanced HIV infection.

Predisposing factors include TB, CHF, mycobacterial infection, cryptococcal infection, pulmonary infection, lymphoma, and KS.

Diseases of the Oropharynx and Diseases of the Oropharynx and Gastrointestinal SystemGastrointestinal System

Oral lesions, including thrush, hairy leukoplakia, and aphthous ulcers are particularly common in patients with untreated HIV infection.

Esophagitis may be due to Candida, CMV, or HSV.

Diseases of the Oropharynx and Diseases of the Oropharynx and Gastrointestinal SystemGastrointestinal System

Cryptosporidia, microsporidia, and Isospora belli are the most common opportunistic protozoa that infect the gastrointestinal tract and cause diarrhea in HIV-infected patients.

The initial evaluation of a patient with HIV infection and diarrhea should include a set of stool examinations, including culture, examination for ova and parasites, and examination for Clostridium difficile toxin.