Illicit drug use is a major health issue globally. It is estimated that in 2011 between 167 and 315 million people worldwide used illicit substances.¹ In 2012, an estimated 23.9 million Americans ≥12 years of age used an illicit drug within the previous month, and of these, 669,000 used heroin, nearly triple the prevalence in 2008.² Between 2006 and 2011, heroin-related ED visits increased from 189,780 to 258,482, with the majority of visits made by men (69%) and patients age 35 to 44 years.² More recently, ED visits due to severe overdoses have been precipitated by drug distributor substitution of the synthetic opiate fentanyl for heroin as a “super high.”³

The practice of injection drug use and the lifestyle and culture of the injection drug user place the individual at risk for a wide variety of complications, including human immunodeficiency virus (HIV) infection, hepatitis, tetanus, sexually transmitted diseases, trauma, and intimate partner violence.⁴ The high incidence of migration, incarceration, homelessness, nutritional deficiencies, coincident smoking and alcohol use, and mental illness further compromises this population’s health.⁵

Injection drug use is associated with immune dysregulation. Exaggerated and atypical lymphocytosis, diminished lymphocyte responsiveness to mitogenic stimulation and depressed chemotaxis, hypergammaglobulinemia, increased opsonin production, decreased T-cell and natural killer cell activity, high levels of circulating immune complexes, and reticuloendothelial abnormalities have been found in injection drug users. False-positive results on nontreponemal syphilis serologic tests, positive results on Coombs tests, low measured antibody response to vaccination, and thrombotic thrombocytopenic purpura are some described abnormalities. HIV-infected patients who inject drugs are found to be less likely to suppress HIV-1 RNA than those who do not inject drugs. Given the immune dysfunction, febrile injection drug users should be suspected of having infections, even when the fever is low grade and WBC counts and erythrocyte sedimentation rates are normal.

To adequately evaluate the histories of injection drug users, be aware of the drugs used locally and regionally, drug street names (e.g., “smack,” “H,” “Mexican mud,” “junk,” “bud light,” “theraflu”), and drug adulterants. Ask about drug type(s) and amount, preparation of materials for injection (e.g., crushing capsules in the mouth, licking needles, blowing on injection sites or blowing out clots in needles, or using saliva, lemon juice, or tap or toilet water for drug reconstitution), reuse of needles, needle sharing, use of antibiotics, and coincident medical and mental illness. Consider socioeconomic issues, such as the ability to purchase medications and access to outpatient follow-up, in patient disposition.

Complications of injection drug use may be obvious, such as a painful, erythematous, fluctuant skin abscess. However, subtle constitutional symptoms such as weakness, anorexia, body pains, myalgias and arthralgias, weight loss, and fever are common and may be the only signs of serious underlying disease (Table 296-1).

FEVER

Fever is associated with infection in more than two thirds of patients. Noninfectious causes of fever include acute toxic reactions to substances of abuse, reactions to injected adulterants, and withdrawal syndromes. Cocaine and amphetamines can cause acute fever, occasionally in excess of 40°C (104°F). Adulterants used to dilute active substances may also cause dramatic febrile reactions accompanied by alteration in mental status and leukocytosis. “Cotton fever” is a flulike syndrome developing within hours of injection, after the use of cotton balls as filters for drug suspensions. Physical findings may include tachypnea, tachycardia, abdominal pain, and inflammatory retinal nodules. Chest radiographs typically show normal findings but may demonstrate inflammatory pulmonary granulomata. This syndrome spontaneously resolves within 24 hours.⁶ Drug withdrawal from benzodiazepines, barbiturates, or heroin also may cause acute illness with chest and abdominal pain, diaphoresis, tachycardia, and fever.

Because no reliable markers are available to exclude serious illness in the febrile injection drug user, common practice has been to obtain specimens for blood culture and admit such patients for observation while culture results are awaited (also see “Infective Endocarditis” section below). In clinically well patients for whom follow-up can be ensured, outpatient evaluation is reasonable as long as appropriate culture specimens are obtained.

DYSPNEA

A wide range of both infectious and noninfectious entities may produce dyspnea and cough in injection drug users. Pneumonia is typically community acquired (see “Pulmonary Infections” section below). However, dyspnea may have other infectious causes, including infections related to aspiration during drug intoxication, tuberculosis, opportunistic infections, and septic pulmonary emboli complicating right-sided endocarditis. The febrile injection drug user with dyspnea, cough, or abnormal findings on chest radiograph should be placed in respiratory isolation until tuberculosis has been excluded and/or an alternative diagnosis is found.⁷

Noninfectious causes of dyspnea include pneumothorax, hemothorax, toxic reaction to injected substances, and hypersensitivity reaction. Pneumothorax and hemothorax are seen most commonly in association with the practice of “pocket shooting,” in which drug users, or their drug-injecting partners, inject into veins in the supraclavicular fossa to access the subclavian, jugular, or brachiocephalic vein. “Talc lung” is a syndrome of progressive respiratory distress and diffuse interstitial infiltrates caused by the injection of adulterant talc. Hypersensitivity reactions, associated with both heroin and cocaine injection, cause cough and wheezing and typically respond to inhaled β-agonist therapy. Noncardiogenic pulmonary edema is associated with both heroin and cocaine use. Signs and symptoms include dyspnea, hypoxia, and diffuse alveolar infiltrates on chest x-ray. Treatment is supportive. Finally, septic, air, or needle fragment emboli can produce dyspnea.

ALTERED MENTAL STATUS AND NEUROLOGIC ABNORMALITIES

Drug intoxication or withdrawal, stroke syndromes, hypoxia, delayed leukoencephalopathy, infectious diseases, mycotic aneurysms, and secondary trauma from either loss of consciousness and fall or drug-related violence may all produce altered mental status or other neurologic impairment in the injection drug user. CNS infections may result from contiguous spread of overlying soft tissue infection, embolic complications of distant infections (e.g., endocarditis), or extension of local infections (e.g., vertebral osteomyelitis). Infections that affect the nervous system and commonly occur in this population include epidural abscess, bacterial and fungal meningitis, and brain abscess. Meningococcus, pneumococcus, and Staphylococcus aureus bacteremia from primary endocarditis are the common causes of bacterial meningitis. Both tetanus and botulism are reported, with cranial nerve involvement, altered mental status, and progressive symmetric paralysis.⁸

Infections caused by opportunistic organisms, such as Toxoplasma, are common in patients with coincident HIV infection who have low CD4 counts (especially <100). Stroke syndromes may occur secondary to low-flow states during heroin intoxication; hypertensive hemorrhage from amphetamines, phencyclidine, or cocaine; and embolized vegetations associated with infectious endocarditis. Delayed leukoencephalopathies, both hypoxic and nonhypoxic, have been reported in injection drug users, but are rare.

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