1.3

• Aseptic meningitis


  Commonly caused by a number of different enteroviruses
• Aseptic meningitis infections tend to be seasonal with peak periods occurring in late summer, early fall
• Tables with information on viral infections of the central nervous system

  • Table 18-8
  • Table 18-9
  • Table 18-10
• Lymphocytic choriomeningitis


  A rodent-borne viral disease that presents as aseptic meningitis, encephalitis, or meningoencephalitis
• Lymphocytic choriomeningitis can also cause asymptomatic or mild febrile disease with symptoms like fever, malaise, suppressed appetite, muscle aches, headache, nausea, vomiting, sore throat, coughing, joint pain, chest pain, and salivary gland pain
• Possible complications of CNS involvement in lymphocytic choriomeningitis include deafness and temporary or permanent neurologic damage
• An association between lymphocytic choriomeningitis virus (LCMV) infection and myocarditis has been suggested
• Standard Precautions


  Precautions used for hospitalized patients with lymphocytic choriomeningitis
• Table 18-11 provides a recap of some major viral infections of humans
• Recommendations for the treatment of infectious diseases change frequently
• Viral infections must be treated using appropriate antiviral drugs
• For certain diseases, serum immune globulins (e.g., varicella-zoster immune globulin) are available for treatment
• Additional information about antiviral agents can be found in Chapter 9 and at en.wikipedia.org/wiki/Antiviral_drug
• Lymphocytic choriomeningitis


  Caused by LCMV, a member of the family Arenaviridae
• Reservoirs and mode of transmission for lymphocytic choriomeningitis

  • Infected rodents, primarily the common house mice
  • Humans become infected following exposure to mouse urine, droppings, saliva, or nesting materials
  • The virus can enter broken skin; through nose, the eyes, or mouth; or via the bite of an infected rodent
  • Organ transplantation is a possible means of transmission
  • Person-to-person transmission does not occur
• Laboratory diagnosis of lymphocytic choriomeningitis

  Primarily by immunodiagnostic procedures and cell culture
• Poliomyelitis (polio, infantile paralysis)


  • In most patients, causes a minor illness with fever, malaise, headache, nausea, and vomiting
  • In about 1% of patients, the disease progresses to severe muscle pain, stiffness of the neck and back, with or without flaccid paralysis
  • Major illness is more likely to occur in older children and adults
• Vaccines became available in the 1950s and the WHO is attempting to eradicate polio worldwide
• Contact Precautions


  Precautions used for hospitalized patients with poliomyelitis for the duration of illness
• Rabies


  • A usually fatal, acute viral encephalomyelitis of mammals, with mental depression, restlessness, headache, fever, malaise, paralysis, salivation, spasms of throat muscles, convulsions, and death caused by respiratory failure
  • The paralysis usually starts in the lower legs and moves upward through the body
• Rabies is endemic in every country of the world except Antarctica and in every state except Hawaii
• Worldwide, over 55,000 people die of rabies annually
• Standard Precautions


  Precautions used for hospitalized patients with rabies
• Viral meningitis


  • Also known as aseptic meningitis and nonbacterial or abacterial meningitis
  • A relatively common disease but, fortunately, is rarely serious
  • Acute illness rarely exceeds 10 days duration
  • Characterized by sudden onset of febrile illness with the signs and symptoms of meningeal involvement
  • CSF findings include the presence of mononuclear white blood cells, increased protein levels, normal glucose levels, and the absence of bacteria
  • A rash may develop
  • When caused by an enterovirus, GI and respiratory symptoms may occur
• Standard Precautions


  Precautions used for hospitalized patients with viral meningitis
• Contact Precautions


  Additional precautions used for infants and young children with viral meningitis
• Viral encephalitis (arthropod-borne viral encephalitis)

  • An acute inflammatory viral disease
  • A patient may be asymptomatic or have mild fever and headache
  • Severe infection is also possible, with headache, high fever, stupor, disorientation, coma, tremors, occasional convulsions, spastic paralysis, and death
• Arthropod-borne viruses


  Viruses that are transmitted by arthropods
• Standard Precautions


  Precautions used for hospitalized patients with viral encephalitis
• Transmission-Based Precautions


  May be necessary for viral encephalitis, depending on the etiologic agent
• Poliomyelitis


  Caused by polioviruses, RNA viruses in the family Picornaviridae
• Reservoirs and mode of transmission for poliomyelitis

  • Infected humans serve as reservoirs
  • Transmission is from person to person, primarily via the fecal-oral route; also by throat secretions
• Laboratory diagnosis of poliomyelitis

  Made by isolation of poliovirus from stool samples, cerebrospinal fluid (CSF), or oropharyngeal secretions using cell culture techniques or by immunodiagnostic or molecular diagnostic procedures
• Rabies virus


  A bullet-shaped, enveloped RNA virus in the family Rhabdoviridae
• Reservoirs for rabies


  • Various wild and domestic mammals, including dogs, foxes, coyotes, wolves, jackals, skunks, raccoons, mongooses, and bats
• Transmission of rabies


  • Usually via the bite of a rabid animal, which introduces virus-laden saliva
  • Airborne transmission from bats in caves also occurs
  • Person-to-person transmission is rare
• Laboratory diagnosis of rabies

  Made by cell culture, antibody detection in serum or CSF, antigen detection in tissue samples, molecular diagnostic procedures for brain tissue, or observation of Negri bodies in brain or other tissues
• Viral meningitis pathogens


  • The most common causes in the United States are enteroviruses, such as coxsackie and enteric cytopathic human orphan (ECHO) viruses
  • Other causes include arboviruses, measles virus, mumps virus, herpes simplex viruses and VZV, lymphocytic choriomeningitis virus, and adenoviruses
  • Leptospirosis (a bacterial disease) can also cause aseptic meningitis
• Reservoirs and mode of transmission for viral meningitis


  • Vary with the specific etiologic agent
• Laboratory diagnosis of viral meningitis


  • During the early stages of the disease, the viral pathogen may be isolated from throat washings and stool, and occasionally from CSF and blood
  • Diagnosis is made by immunodiagnostic, molecular diagnostic procedures, or cell culture