Revised Surveillance Case Definition for HIV Infection

Since the first cases of acquired immunodeficiency syndrome (AIDS) were reported in the United States in 1981, surveillance case definitions for human immunodeficiency virus (HIV) infection (the cause of AIDS) and AIDS have undergone several revisions to respond to diagnostic advances. Continue reading

WHO Immunological Classification for Established HIV Infection

The revised clinical staging and immunological classification of HIV are designed to assist in clinical management of HIV, especially where there is limited laboratory capacity. Continue reading

Severity Criteria for Clostridium difficile Infection

Patients with severe disease may develop a colonic ileus or toxic dilatation and present with abdominal pain and distension but with minimal or no diarrhea. Complications of severe C. difficile colitis include dehydration, electrolyte disturbances, hypoalbuminemia, toxic megacolon, bowel perforation, hypotension, renal failure, systemic inflammatory response syndrome, sepsis, and death.

Definitions of Clostridium difficile Infection (CDI)

Clostridium difficile ( C. difficile ) is a Gram-positive, sporeforming bacterium usually spread by the fecal-oral route. It is non-invasive and produces toxins A and B that cause disease, ranging from asymptomatic carriage, to mild diarrhea, to colitis, or pseudomembranous colitis. CDI is defined as the acute onset of diarrhea with documented toxigenic C. difficile or its toxin and no other documented cause for diarrhea.

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Interpretation of Dengue Diagnostic Tests

Dengue virus infection produces a broad spectrum of symptoms, many of which are non-specific. Thus, a diagnosis based only on clinical symptoms is unreliable. Early laboratory confirmation of clinical diagnosis may be valuable because some patients progress over a short period from mild to severe disease and sometimes to death. Early intervention may be life-saving.

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Symptoms and Diagnosis of Zika Virus Infection

Zika virus is spread to people through mosquito bites. The most common symptoms of Zika virus disease are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting from several days to a week. Severe disease requiring hospitalization is uncommon.

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Case Definition for Ebola Virus Disease (EVD)

Early recognition is critical for infection control. Healthcare providers should be alert for and evaluate any patients suspected of having EVD.

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Criteria for Health Care–Associated Pneumonia

Health care-associated pneumonia has been categorized as a discrete entity, with the goal of identifying patients with pneumonia that develops outside the hospital yet is caused by pathogens usually associated with hospital-acquired pneumonia or even ventilator-associated pneumonia, including methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) gram-negative pathogens.

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Indications for Antiviral Treatment in Patients with Herpes Zoster

Primary infection with varicella–zoster virus (VZV) results in chickenpox, characterized by viremia with a diffuse rash and seeding of multiple sensory ganglia, where the virus establishes lifelong latency. Herpes zoster is caused by reactivation of latent VZV in cranial-nerve or dorsal-root ganglia, with spread of the virus along the sensory nerve to the dermatome.

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Diagnostic Criteria for Chronic HBV Infection

Chronic HBV infection is a necroinflammatory disease of the liver caused by persistent infection with HBV, and can be categorized as hepatitis B e antigen (HBeAg) positive or negative. Inactive hepatitis B surface antigen (HBsAg) carriers have HBV infection of the liver without significant, ongoing necroinflammatory disease. HBV infection is resolved when there is no further virologic, biochemical, or histologic evidence of active viral infection or disease.

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