Intravenous drug use and blood-borne diseases

DEFINITION: Intravenous drug use is the administration of drugs, usually proscribed substances, by injection directly into the bloodstream. Numerous pathogenic microorganisms are transmitted in this way, which can lead to infectious diseases in individuals who use intravenous drugs.

Causes

Blood-borne pathogens such as parasites, viruses, and bacteria can be transmitted by injection drug abuse. Some of these pathogens and associated diseases are described here.

Malaria. Plasmodium outbreaks among individuals who use injection drugs have been reported since the early twentieth century when the first cases were reported in Africa. Needle sharing was suspected, but analysis of blood found in syringes did not show the Plasmodium falciparum parasite. Malaria eventually became common in injection drug users in New York City, with about 135 fatal cases in the ten-year period preceding US involvement in World War II. Nonfatal cases of P. vivax malaria were also reported. The outbreak was limited to individuals who use intravenous heroin. Cases were typically attributed to sailors who traveled to the tropics. The sharing of needles was the mode of transmission during these outbreaks. The addition of quinine, an antimalarial drug, to cut or dilute heroin dramatically reduced cases.

Hepatitis. The sharing of needles by people with an addiction was noted as the cause of hepatitis B virus (HBV) transmission in the mid-nineteenth century. HBV outbreaks associated with injection drug use are still noted today. Research into the prevalence of HBV among injection drug users shows that nearly 23 percent of all people who use intravenous drugs have been exposed to the virus. Combined HBV, hepatitis delta, or hepatitis C virus (HCV) infection causes hepatitis outbreaks among injection drug abusers that are sometimes fatal. HCV became the most common blood-borne infection in the United States in the 1970s. Globally, 23 to 39 percent of individuals newly infected with HCV and about 30 percent of those who die from HCV use intravenous drugs. Each hepatitis infection is most common among those exposed to blood, including people who use intravenous drugs.

Human immunodeficiency virus (HIV). Individuals who use intravenous drugs are at great risk for acquired immunodeficiency syndrome (AIDS) in the United States, comprising one-tenth of new cases each year. Needle sharing is the greatest risk for exposure and transmission. In 2010, forty-three percent of individuals with an injection drug addiction tested positive for the virus, but a decade later, this rate was much lower because of education initiatives and services like the Centers for Disease Control’s syringe services programs (SSPs). Other human retroviruses, such as human T-cell lymphotropic virus, types I and II, are also transmitted among persons who inject drugs.

Clostridial disease. Tetanus among persons who inject drugs is not uncommon in females, though the reason for elevated susceptibility in women is unclear. Clostridium tetani bacteria and spores likely originate in the environment. However, contamination of heroin is possible, too. Also, botulism caused by C. botulinum infection originating at the injection wound site has been reported among parenteral drug abusers. If not treated, tetanus can lead to a necrotizing soft-tissue infection, which can be deadly. Immunizations and treatments are available, but many individuals who use intravenous drugs are hesitant to seek and complete care.

Candida. Candida parapsilosis is the most common etiologic agent of fungal endocarditis among individuals with an injection drug addiction. Viable cells have been recovered from both heroin and injection paraphernalia. Because this fungus is a member of the oral flora, individuals who inject drugs may be the reservoirs. C. albicans infection of the skin, eyes, bones, and joints has also been noted.

Pseudomonas aeruginosa. Serogroup 0-11 P. aeruginosa endocarditis is noted almost exclusively in intravenous drug users. Tablets of pentazocine, an analgesic, and tripelennamine, an antihistamine, are crushed, diluted in tap or toilet water without boiling, and then injected. The bacterium grows readily in these preparations.

Polymicrobial bacteremia. Seventy percent of blood cultures from individuals who inject drugs with polymicrobial bacteremia grow Staphylococcus aureus along with other bacteria. Therefore, skin contamination and poor hygiene are risk factors. As with P. aeruginosa bacteremia, pentazocine and tripelennamine abuse is a risk factor for polymicrobial bacteremia.

Staphylococcus aureus. A common cause of bacterial endocarditis, skin and soft tissue infections, and bacteremia in individuals who use intravenous drugs is S. aureus. The source of the bacteria is likely the individual's own skin. Outbreaks of methicillin-resistant S. aureus (MRSA) have been reported. Antibiotic abuse, long periods of injection drug abuse, and frequent hospitalizations are associated with MRSA bacteremia.

Mycobacterium tuberculosis. The incidence of active tuberculosis is higher among hospitalized or methadone treatment patients than in the general population. Suppression of the immune system from drug abuse likely leads to an elevated number of infections among those exposed.

Risk Factors

The lifestyle of individuals who use intravenous drugs makes them vulnerable to infection. People with an addiction repeatedly inject substances with immunosuppressive effects that are frequently in contaminated diluents. Immunologic defenses also are compromised by the simultaneous abuse of alcohol and tobacco and by personal neglect. The ongoing opioid crisis in the early twenty-first century in the United States increased the risk for hepatitis B, hepatitis C, and HIV as drug users share contaminated injection devices.

Several factors may influence the susceptibility of individuals who use intravenous drugs to be exposed to bacteria, viruses, or parasites. The most important factor in reduced tolerance to infection is the damaged skin of the injection drug abuser. Needle wounds lead to abscesses and result in higher S. aureus skin colonization. Destruction of nasal mucosa, depression of cough and gag reflex, and dental carries lead to increased susceptibility. The individual with SUD also may have impaired functioning of phagocytosis, reduced superoxide production, and reduced T-cell function.

Symptoms

The symptoms of blood-borne disease vary with the specific diagnosis. General symptoms of infection include fever and inflammation. Also common are body aches, headaches, nausea, and vomiting. Hepatitis cases can result in jaundice.

Screening and Diagnosis

Diagnosis of infectious diseases among individuals who use intravenous drugs is performed in a manner identical to other patients. Fluid or tissue samples must be obtained aseptically and delivered to the microbiology lab. Growth of the specimen is limited to about two hours, so the composition of the flora represents that of the original sample.

A fixed smear is Gram-stained for preliminary identification of Gram-positive or Gram-negative bacteria. Multiple test kits are available for more specific identification of bacterial pathogens. The presence of antibodies directed against a pathogen is used in the presumptive diagnosis of hepatitis viruses and HIV. In rare cases, genetic analysis is performed to identify an infectious agent.

A urinalysis and a complete blood count checking white blood cell differential, serum electrolytes, urea, nitrogen, creatinine, glucose, and transaminases should be obtained. A chest X-ray and films of any involved soft tissues and bone should be taken. While bone scans are a valuable diagnostic tool, they are usually not available in emergency rooms, where individuals who use intravenous drugs with infections frequently are treated. A computerized tomography scan of the brain should be ordered if there are neurologic symptoms or signs.

Treatment and Therapy

The treatment of blood-borne disease in injection drug abusers varies by diagnosis. Chloroquine is frequently used in the treatment of malaria, but quinidine or quinine plus doxycycline, tetracycline, or clindamycin, or atovaquone plus proguanil, are used in the treatment of chloroquine-resistant infections. The hepatitis viruses are treated with antivirals, and HIV is treated with antiretroviral drugs.

Mifepristone and misoprostol are used in the treatment of clostridial disease. Amphotericin B has been the most frequently used antifungal in the treatment of candida infections. Fluconazole is frequently administrated as an alternative to amphotericin B. P. aeruginosa is naturally resistant to a host of antibiotics. However, several injectable drugs can be effective. Ceftaroline is a broad-spectrum cephalosporin used in the treatment of MRSA infections. With any infectious disease, treatment of the addiction is essential to the long-term health of the individual who uses intravenous drugs.

Prevention

It remains difficult to control and prevent infectious diseases among individuals who use intravenous drugs. Most individuals are elusive and seek care in the mainstream healthcare system only when very ill or when facing withdrawal. Socioeconomic factors such as poverty, illiteracy, and language and cultural barriers are often further impediments to effective care.

With the fear that individuals with HIV who use intravenous drugs may be a significant reservoir for the general public, health departments began acting. For example, they employed individuals who formerly used intravenous drugs to educate current users about blood-borne diseases and risk reduction. Health experts hoped these programs would result in a concomitant decrease in the incidence of other infections associated with needle sharing and patronage of injection-drug “shooting galleries.” Additionally, clean needles and other health supplies became available through programs such as the Centers for Disease Control’s syringe services programs. For three decades, these programs proved to be safe, effective, and cost-saving. They prevent the spread of disease and do not encourage or increase the incidence of intravenous drug use. Hepatitis B and tetanus immunization are effective in the prevention of these diseases.

Bibliography

“HIV.” Centers for Disease Control and Prevention, www.cdc.gov/hiv. Accessed 2 Sept. 2024.

"Infectious Diseases in Persons Who Inject Drugs." Centers for Disease Control and Prevention, 16 Feb. 2024, www.cdc.gov/pwid/opioid-use.html. Accessed 2 Sept. 2024.

Levine, Donald P., and Jack D. Sobel, editors. Infections in Intravenous Drug Abusers. Oxford UP, 1999.

Tortora, Gerard J., et al. Microbiology: An Introduction. 14th ed., Pearson, 2023.