Meningitis airborne or droplet

Viral Meningitis

On This Page

  • Causes
  • People at Risk
  • How it Spreads
  • Symptoms
  • Diagnosis
  • Treatment
  • Prevention

Viral meningitis is the most common type of meningitis, an inflammation of the lining of the brain and spinal cord. It is often less severe than bacterial meningitis, and most people get better on their own (without treatment). However, anyone with symptoms of meningitis should see a doctor right away because some types of meningitis can be very serious. Only a doctor can determine if someone has meningitis, what is causing it, and the best treatment. Babies younger than 1 month old and people with weakened immune systems are more likely to have severe illness from viral meningitis.

Causes

Non-polio enteroviruses are the most common cause of viral meningitis in the United States, especially from late spring to fall. That is when these viruses spread most often. However, only a small number of people infected with enteroviruses will actually develop meningitis.

Other viruses that can cause meningitis are

  • Mumps virus
  • Herpesviruses, including Epstein-Barr virus, herpes simplex viruses, and varicella-zoster virus (which causes chickenpox and shingles)
  • Measles virus
  • Influenza virus
  • Arboviruses, such as West Nile virus
  • Lymphocytic choriomeningitis virus

People at Risk

People of any age can get viral meningitis. However, some people have a higher risk of getting the disease, including:

  • Children younger than 5 years old
  • People with weakened immune systems caused by diseases, medications (such as chemotherapy), and recent organ or bone marrow transplantations

Babies younger than 1 month old and people with weakened immune systems are also more likely to have severe illness.

How it Spreads

Close contacts of someone with viral meningitis can become infected with the virus that made that person sick. However, these close contacts are not likely to develop meningitis. Only a small number of people who get infected with the viruses that cause meningitis will actually develop viral meningitis.

Viruses that can cause meningitis spread in different ways. Learn more about how the following viruses spread by visiting CDC’s websites:

  • Non-polio enteroviruses
  • Mumps virus
  • Herpesviruses, including Epstein-Barr virus, herpes simplex viruses, and varicella-zoster virus
  • Measles virus
  • Influenza virus
  • Arboviruses, like West Nile virus
  • Lymphocytic choriomeningitis virus

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Symptoms

Common symptoms in babies

  • Fever
  • Irritability
  • Poor eating
  • Sleepiness or trouble waking up from sleep
  • Lethargy (a lack of energy)

Common symptoms in children and adults

  • Fever
  • Headache
  • Stiff neck
  • Eyes being more sensitive to light
  • Sleepiness or trouble waking up from sleep
  • Nausea
  • Irritability
  • Vomiting
  • Lack of appetite
  • Lethargy (a lack of energy)

Most people with mild viral meningitis usually get better on their own within 7 to 10 days.

Initial symptoms of viral meningitis are similar to those for bacterial meningitis. However, bacterial meningitis is usually severe and can cause serious complications, such as brain damage, hearing loss, or learning disabilities. The pathogens (germs) that cause bacterial meningitis can also be associated with another serious illness, sepsis. Sepsis is the body’s extreme response to infection. Without timely treatment, sepsis can quickly lead to tissue damage, organ failure, and death.

See a doctor right away if you think you or your child might have meningitis. A doctor can determine if you have the disease, what is causing it, and the best treatment.

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Diagnosis

Doctors diagnose meningitis by ordering specific lab tests on specimens from a person suspected of having meningitis. If a doctor suspects meningitis, he or she may collect samples for testing by:

  • Swabbing your nose or throat
  • Obtaining a stool sample
  • Taking some blood
  • Drawing fluid from around your spinal cord

Treatment

In most cases, there is no specific treatment for viral meningitis. Most people who get mild viral meningitis usually recover completely in 7 to 10 days without treatment. Antiviral medicine may help people with meningitis caused by viruses such as herpesvirus and influenza.

Antibiotics do not help viral infections, so they are not useful in the treatment of viral meningitis. However, antibiotics do fight bacteria, so they are very important when treating bacterial meningitis.

People who develop severe illness, or are at risk for developing severe illness may need care in a hospital.

Prevention

There are no vaccines to protect against non-polio enteroviruses, which are the most common cause of viral meningitis. The best way to help protect yourself and others from non-polio enterovirus infections is to

  • Wash your hands often with soap and water for at least 20 seconds, especially after changing diapers or using the toilet
  • Avoid close contact, such as touching and shaking hands, with people who are sick
  • Clean and disinfect frequently touched surfaces
  • Stay home when you are sick and keep sick children out of school

Vaccines can protect against some diseases, such as measles, mumps, chickenpox, and influenza, which can lead to viral meningitis. Make sure you and your child are vaccinated on schedule.

Avoid bites from mosquitoes and other insects that carry diseases that can infect humans.

Control mice and rats. If you have a rodent in or around your home, follow appropriate cleaning and control precautions.

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The common signs and symptoms associated with meningitis and septicaemia can appear in any order, and some may not appear at all.

In adults and children:

Fever with cold hands and feet – Vomiting – Drowsy, difficult to wake – Confusion and irritability – Severe muscle pain – Pale blotchy skin, spots or a rash that does not fade under pressure – Severe headache – Stiff neck – Dislike of bright lights – Convulsions/seizures

In babies and toddlers:

Fever with cold hands and feet – Refusing food or vomiting – Fretful, dislike of being handled – Drowsy, floppy, unresponsive – Rapid breathing or grunting – Pale blotchy skin, spots or a rash that does not fade under pressure – Unusual cry, moaning – Tense, bulging fontanelle – Neck stiffness – Dislike of bright lights – Convulsions/seizures

What is the rash?

When meningococcal bacteria multiply in the blood stream, they release toxins (poisons) that damage the blood vessels. The rash is caused by blood leaking from the damaged blood vessels into the tissues underneath the skin.

What does it look like?

The rash can start anywhere on the body. It begins as tiny red pin pricks, but may quickly develop to look like fresh bruising. The Glass Test can be used to see if the rash might be septicaemia. If you press the side of a clear drinking glass firmly onto the spots or bruises, they will not fade. A rash will not always appear with meningitis and can be one of the last symptoms to be displayed. Never wait for a rash if you suspect meningitis.

Are signs and symptoms different for septicaemia?

If someone has septicaemia alone, the common signs of meningitis, such as a severe headache or neck stiffness, may not be present. The early signs and symptoms of septicaemia include:

  • Fever with cold hands and feet
  • Severe muscle pain
  • Pale blotchy skin
  • Stomach cramps and diarrhoea

Septicaemia can progress very quickly, resulting in severe shock and, in some cases, death within hours. If septicaemia is suspected, urgent medical help is needed.

What should you do if someone has signs and symptoms?

If you have identified signs and symptoms and someone’s general health is deteriorating, you need to act quickly.

  • Seek medical help immediately
  • Describe the symptoms as accurately as possible
  • Say that you think it could be meningitis or septicaemia
  • If you have had advice and are still worried, get medical help again

The National Institute for Health and Care Excellence (NICE) provides national guidance and advice to improve health and social care. The following links are relevant to the diagnosis and treatment of meningitis and septicaemia:

Bacterial meningitis and septicaemia

Fever in the under 5s

Sepsis

Back to Bugs and Outbreaks page

Meningitis means an inflammation of the lining of the brain and spinal cord (called the meninges). It can be caused by infectious or non-infectious agents. The degree of morbidity and mortality associated with meningitis varies with the causative agent, the age of the person, and any preexisting medical conditions.

Bacteria, virus, parasites, and fungi are infectious causes of meningitis; some non-infectious agents include drugs, radiographic dyes, and tumors.

The symptoms of infectious meningitis include fever, headache, stiff neck (called nuchal rigidity), nausea, vomiting, eye discomfort in bright light (called photophobia), irritability, and change in mental status. Infants may have poor feeding.

Bacterial meningitis
The most common bacterial causes are Group B Streptococcus (GBS), Streptococcus pneumoniae (also called pneumococcus), Haemophilus influenzae, Neisseria meningitides (also called meningococcus), and Listeria monocytogenes.

Bacterial meningitis is NOT spread through casual contact or the airborne route; however, some bacteria can be spread by close contact with respiratory droplets (e.g., in daycare centers). Based on age or risk factors, certain persons should receive vaccinations for GBS, Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitides. Antibiotic prophylaxis is only indicated for close contacts of persons with Haemophilus influenzae or meningococcal meningitis. Healthcare workers do not have a high risk of catching meningococcal meningitis and prophylaxis is indicated only for persons directly exposed to the patient’s oral secretions (e.g., mouth-to-mouth resuscitation, endotracheal intubation, or endotracheal tube management).

Viral meningitis
Viral meningitis, often referred to as aseptic meningitis, is generally a self-limiting illness. It can affect anyone, but the very young and persons with weakened immune systems are at the highest risk. The following viruses can cause meningitis:

  • Enteroviruses— the most common cause
  • Mumps and measles
  • Herpes virus, including Epstein-Barr virus, herpes simplex viruses, and varicella-zoster virus
  • Influenza
  • Viruses spread through mosquitoes and other insects (arboviruses)
  • Lymphocytic choriomeningitis virus

Enteroviral infections can be spread person to person via fecal contamination. Enteroviruses and viruses such as mumps and varicella may also be spread through direct or indirect contact with saliva, sputum, or mucus of an infected person. Antibiotics are not effective for viral meningitis although antiviral treatment is available for herpes viruses. Thus, post exposure prophylaxis is not indicated.

What you can do:
It can be difficult to distinguish the cause of meningitis based on symptoms, although the presentation of viral meningitis tends to be less severe than bacterial cases. Laboratory tests, specifically blood cultures and cerebrospinal fluid (CSF) analysis, will assist with determining the treatment, need for precautions, and potential prophylaxis of contacts.

A comparison of CSF results helps distinguish between bacterial and viral causes:

Glucose Protein WBC Type of cells
Bacterial Normal to decreased Increased > 1000/mm3 Neutrophils
Viral Normal Normal to increased < 100/ mm3 Lymphocytes

If the patient has not had any antibiotics, the gram stain in bacterial meningitis will be positive, whereas it will be negative for viral meningitis. Bacterial antigen tests and cultures will further determine the specific organisms.

Healthcare personnel should use standard precautions when caring for meningitis patients. Transmission based precautions should be followed for disease-specific illness. For example:

  • Meningococcal – droplet for 24 hours after effective treatment
  • Haemophilus influenza – droplet for 24 hours after effective treatment
  • Enterovirus – Contact precautions for diapered or incontinent children for duration of illness

Prevention is key. Be sure to encourage vaccination for those most at risk for bacterial meningitis.

Learn more and share:

  • Meningococcal disease: What it is and how to prevent it—APIC Consumer Alert
  • Meningococcal disease: What you need to know—APIC Consumer Alert
  • Meningitis—The Centers for Disease Control and Prevention
  • Guideline for Isolation Precautions—The Centers for Disease Control and Prevention

Bacterial Meningitis

Perhaps no admission causes so much consternation and dread amongst caregivers and families as a case of suspected bacterial meningitis. Will the patient live? What infection control precautions are necessary? And, perhaps most urgently, do I need antibiotic prophylaxis? In this article I answer the questions hospitalists most often need to address in such circumstances.

1. Who should have a head CT prior to lumbar puncture (LP) for suspected meningitis? Patients with immunocompromise, papilledema, preexisting CNS disease, new onset seizures, altered level of consciousness, and focal neurological findings should have a head CT prior to LP.1 While herniation is rare after LP for purulent meningitis, patients with increased intracranial pressure at risk for herniation often have normal head CT scans. Therefore, herniation may be an uncommon but unpredictable complication of LP in this setting. The cause-and-effect relationship of herniation and LP has also been questioned.

2. Are there any cerebrospinal fluid (CSF) findings that exclude bacterial meningitis? A number of CSF findings make bacterial meningitis quite likely, including total leukocyte counts of more than 2,000/mm3, a positive gram stain, or very low CSF glucose. It is difficult, if not impossible, however, to exclude bacterial meningitis in patients with any degree of CSF pleocytosis. For example, 10% of patients with bacterial meningitis have less than 100 WBCs/mm3 in CSF, and 10% have lymphocyte predominance at presentation. Therefore, the safest course of action when bacterial meningitis is suspected on clinical grounds and CSF pleocytosis is present is to continue antibiotics until results of CSF cultures are available.

3. Which patients with suspected or proven meningitis should receive steroids? Steroids reduce neurologic damage from the inflammatory surge provoked by antibiotic-induced pneumococcal lysis. In a large European trial, dexamethasone given in 10-mg doses every six hours for four days (before or with the first dose of antibiotics) reduced mortality in pneumococcal meningitis.2 Benefits were not seen in patients with bacterial meningitis from other pathogens. Dexamethasone can be safely stopped as soon as pneumococcal meningitis is excluded.

4. How soon should patients receive antibiotics? When bacterial meningitis is likely, antibiotics should be given immediately, prior to imaging studies and lumbar puncture. In patients with a lower clinical likelihood of bacterial meningitis, antibiotics can be deferred, awaiting the results of diagnostic studies.

5. What empiric antibiotic therapy is appropriate? Adults 18-50 with suspected bacterial meningitis should receive therapy directed against Streptococcus pneumoniae and Neisseria meningitidis. Vancomycin should be dosed to achieve a relatively high trough level of 15-20 mcg/mL. For a 70-kg adult male with normal renal function, doses of vancomycin given at the rate of 1.5 gm IV every 12 hours and ceftriaxone at 2 gm IV every 12 hours are appropriate. Adults over 50, alcoholics, and immunocompromised adults of any age should also receive ampicillin doses of 2 gm IV every four hours to cover Listeria, in addition to vancomycin and ceftriaxone.3,4

6. What infection control precautions are required? Meningococcal meningitis patients should be placed on droplet precautions (private room, mask for all entering the room) until they have completed 24 hours of appropriate antibiotic therapy. Negative pressure ventilation is not required. Patients with pneumococcal or viral meningitis do not require isolation.

7. Who needs antibiotic prophylaxis after patient exposure? Chemoprophylaxis is overprescribed after exposures to patients with meningococcal meningitis. The only social contacts who should receive prophylaxis are household contacts, childcare contacts, and people who have had direct exposure to the patient’s oral secretions through actions such as kissing or sharing utensils or toothbrushes. The only healthcare workers requiring chemoprophylaxis are those who performed mouth-to-mouth resuscitation or any staff who were unmasked during intubation or suctioning of a patient. Regimens for chemoprophylaxis in adults include ciprofloxacin, 500 mg taken orally as a single dose, rifampin taken in doses of 600 mg twice daily for two days, or 250 mg of ceftriaxone, given intramuscularly. Ceftriaxone is preferred for pregnant women. Chemoprophylaxis is unnecessary after exposure to patients with pneumococcal or viral meningitis.

8. What is the significance of arthritis after meningococcal meningitis? A significant number of patients with meningococcal disease develop inflammatory polyarthritis about a week after the onset of infection. In most cases, this is a sterile, immune complex phenomenon that responds to anti-inflammatory therapy. If joint effusions are present, they should be aspirated to exclude septic arthritis and crystalline arthritis. TH

Dr. Ross is a hospitalist at Brigham and Women’s Hospital (Boston) and a fellow of the Infectious Diseases Society of America.

  1. Hasbun R, Abrahams J, Jekel J, et al. Computed tomography of the head before lumbar puncture in adults with suspected meningitis. N Engl J Med. 2001 Dec 13;345(24):1727-1733.
  2. de Gans J, van de Beek D. Dexamethasone in adults with bacterial meningitis. European dexamethasone in adulthood bacterial meningitis. N Engl J Med. 2002;347(20):1549-156.
  3. Tunkel AR, Hartman BJ, Kaplan SL, et al. Practice guidelines for the management of bacterial meningitis. Clin Infect Dis. 2004 Nov 1;39(9):1267-1284.
  4. van de Beek D, de Gans J, Tunkel AR, et al. Community-acquired bacterial meningitis in adults. N Engl J Med. 2006 Jan 5;354(1):44-53.


Case Study
D.F. is a 65-year-old male who has brain cancer. He is admitted to a private room in a community hospital for adjustment of anti-seizure medication and to receive chemotherapy. Within 48 hours of admission D.F. develops a rash and fever. Initially, the rash is considered a drug reaction to the anti-seizure medicine and the fever is considered a reaction to the chemotherapy. D.F. complains of a severe headache. An infectious disease physician evaluates him. The differential includes meningitis and tumor. A lumbar puncture is performed to obtain cerebrospinal fluid (CSF) for analysis. The CSF analysis shows elevated opening pressure, elevated protein, low glucose (hypoglycorrhachia), cloudy fluid and a positive Gram stain. Bacterial meningitis is the presumptive diagnosis. Broad-spectrum empiric antibiotic therapy is initiated.

Meningitis
Meningitis is an anxiety-provoking topic for many health care workers who often have common misperceptions about meningitis. These inaccuracies include that meningitis is always infectious; that the agents causing meningitis can be easily transmitted from person to person; that people diagnosed with meningitis are highly infectious; and that meningitis is always associated with severe complications (e.g., death). Nurses play an important role in providing accurate information to dispel these misperceptions and decrease fear and anxiety in patients, family, staff and the public.

Although some types of bacterial meningitis can be catastrophic, the reality is that meningitis is a complex group of diseases with varying severities and epidemiologies. The etiology of meningitis can be either infectious (bacteria or viral) or noninfectious (such as tumor, trauma, brain abscess, subdural empyema or pharmacologic reaction).

Since viral meningitis is often a self-limited disease, it is probably fair to assume that many cases of viral meningitis go undiagnosed and/or do not have a specific etiologic agent identified. The most common pathogens associated with meningitis are listed in Table 1.

A lumbar puncture is the usual procedure performed from which a diagnosis of bacterial vs. viral meningitis can be established. CSF obtained from the lumbar puncture is examined directly and cultured, and the results of these analyses are critical to diagnose either bacterial or viral meningitis. Table 2 summarizes the most common CSF findings associated with bacterial or viral meningitis. Severe complications can result from bacterial meningitis but are not very common from viral meningitis.

Bacterial Meningitis
Worldwide, bacterial meningitis is a common disease, with 75 percent-80 percent of all cases associated with three pathogens: Haemophilis influenzae, Neisseria meningitidis and Streptococcus pneumoniae. In the United States, as of the late 1990s-more than 10 years after licensure of the H. influenzae serotype b vaccine (Hib)-the most common agents are N. meningitidis and S. pneumoniae. During the early 1990s, approximately 25,000 cases occurred annually in the United States, with 70 percent identified among children age 5 or younger. Each year more than 2,000 deaths were attributed to bacterial meningitis.

The predominant organisms responsible for bacterial meningitis vary, depending on the age of the patient (see Table 3). Epidemics of bacterial meningitis do occur and are always associated with N. meningitidis.

Bacterial meningitis in adults is characterized by abrupt onset. Symptoms can include sudden fever, intense headache and meningismus. Signs of meningeal irritation associated with acute febrile illness or dehydration without actual infection of the meninges may be subtle or acute; may or may not be accompanied by Kernig’s sign (inability to extend the leg fully when in a sitting position or when the thigh is flexed upon the abdomen), or Brudzinski’s sign (flexion of the neck resulting in flexion of the hip and knee, or with passive flexion of the lower limb on one side a similar movement occurs on the opposite side). Other signs of cerebral dysfunction (confusion, delirium, declining level of consciousness) may be present. Constitution signs can include nausea, vomiting, rigors, myalgia, weakness and diaphoresis. Seizures occur in up to 40 percent of cases.

A petechial rash may develop in association with N. meningitidis meningitis. However, neonates with bacterial meningitis often do not manifest fever or meningismus-the clinical symptoms may be nonspecific (e.g., irritability, high-pitched crying, listlessness, refusal to feed). Elderly patients may have no fever and the main clinical symptoms may be lethargy/obtundation with variable signs of meningismus.

Bacterial meningitis is diagnosed by CSF examination. Typical findings are: elevated opening pressure, elevated protein and hypoglycorrhachia. The fluid appearance may be cloudy or turbid. The CSF leukocyte concentration is usually elevated with a neutrophilic pleocytosis. CSF Gram stain examination is associated with rapid and accurate organism identification in up to 90 percent of bacterial meningitis cases.

Emergent empirical broad spectrum antimicrobial therapy, based on age, underlying disease status and medical history, should be initiated as soon as a diagnosis of bacterial meningitis is likely even if no bacteria are visualized by Gram stain.

Upon identification of the bacterial pathogen, antimicrobial therapy can be modified based on susceptibility results. Therapy should be individualized and based on the patient’s clinical response. Neurologic sequelae (e.g., hearing loss, seizures and behavioral problems) are associated in about 33 percent -50 percent of bacterial meningitis survivors.

Infection control recommendations for patients with bacterial meningitis-with two important exceptions-are the practice of Standard Precautions, with strict attention to meticulous hand washing. The two exceptions are bacterial meningitis due to either N. meningitidis (meningococcal) or H. influenzae.

Infection Control Precautions
For meningitis caused by either of these two organisms, additional infection control strategies are indicated since transmission can occur by the droplet/close contact route-for up to 24 hours even after starting effective antibiotic therapy.

The Centers for Disease Control and Prevention (CDC) recommends droplet precautions in addition to Standard Precautions for bacterial meningitis caused by either N. meningitidis or H. influenzae. Precautions may be discontinued 24 hours after initiation of effective therapy. When droplet precautions are initiated, the risk for transmission is much lower. The local health department should be notified to arrange for follow-up of household and community contacts.

Meningococcal Meningitis
Because of the potential for an adverse outcome, concern and anxiety are common whenever a meningococcal infection (N. meningitidis) is suspected or diagnosed. The incubation period from exposure to the disease can be 2-10 days, but usually is 3-4 days.

Transmission is by droplet/direct contact with respiratory secretions or contact with laboratory cultures. It is not by aerosols, and thus the risk for transmission from casual or brief contact with infected patients is minimal. In a health care setting, spread of the infection is uncommon.

Health care workers at risk for transmission are those with intense direct contact, e.g., mouth-to-mouth resuscitation, intubation or nasotracheal suctioning without the use of protective barriers, or lab personnel who handle cultures without protection. Only these staff will require chemoprophylaxis.

General exposure guidelines for household contacts and child care contacts are at least 4 hours close contact during the week before the illness onset or mouth-to mouth kissing.

Postexposure chemoprophylaxis can be either rifampin, ciprofloxacin or ceftriaxone. Ciprofloxacin should not be administered to children or pregnant women. Rifampin turns urine, saliva and tears an orange color. Also, it has been associated with nausea, vomiting and rash.

To promote adequate absorption, rifampin should be taken on an empty stomach. Lab staff who have been exposed percutaneously require penicillin prophylaxis. Immunization of health care staff after chemoprophylaxis for sporadic exposure is not indicated.

Vaccine for High-Risk Groups
Meningococcal vaccine, although not routinely recommended, should be given to certain risk groups over 2 years of age-e.g., asplenic people-and is used as a control measure during community and college outbreaks. Additional risk groups susceptible to serious meningococcal infections include persons with terminal complement deficiencies and laboratory personnel who are routinely exposed to N. meningitidis in solutions that may be aerosolized.

Administration of meningococcal vaccine is not indicated for hematopoietic stem cell transplant (HSCT) recipients, but administration of the vaccine should be evaluated for HSCT recipients who live in endemic areas or are experiencing outbreaks.

Bacterial meningitis can be very serious; children are usually hospitalized. Most types of bacterial meningitis will not be spread person-to-person; for the types that can be spread, good hygiene, especially handwashing and environmental cleanliness, are important preventative measures.

Immediate contact with the local health department is very important for the management of bacterial meningitis. Responsibilities of the health department include communicating with the patient’s physician, making recommendations to prevent infection transmission and working with local health care workers and the community to reduce the risk for transmission.

In the school and child care setting, parents of exposed children should receive information about meningitis, recommendations for antibiotics and instructions about what to do if their child develops any symptoms of concern (such as fever, headache, rash) during the incubation period.

H. Ibfluenzae Meningitis
In health care settings, transmission of the bacteria H. influenzae from a patient with the infection is exceedingly rare. Because of widespread use of the Hib vaccine, people are usually not unduly anxious or concerned about this disease. Some people-such as those who live in the same household, attend the same day care or are members of the same classroom-may have more than brief or casual contact with the infected person.

General guidelines to identify persons who may have had more than brief or casual contact are those who were:

  • living with the infected person or had at least 4 hours of exposure to the infected person in the childcare setting or the classroom; or
  • attending the same child care as the infected person for 5-7 days before infection onset.

Rifampin is the agent of choice for chemoprophylaxis, but contraindications (e.g., pregnancy, liver disease, drug interactions) must be considered. Children who have H. influenzae should have their hearing tested after recovery.

Viral Meningitis
Viral meningitis (aseptic meningitis), although common in occurrence, is rarely life threatening. Viral meningitis is generally not a reportable disease (depending on whether a reportable etiologic agent-such as mumps-is identified). For this reason, the actual incidence of viral meningitis is not known. However, seasonal increases occur in late summer and early autumn and are mainly attributed to arbovirus and enterovirus activity.

Seasonal predilection occurs with lymphocytic choriomeningitis virus (fall and winter) and mumps (winter and spring). Identification of the viral agent is challenging-under ideal circumstances, serologic and virology isolation methodology may yield a specific etiologic agent identification for about half of the cases diagnosed.

Viral meningitis symptoms are similar to those for bacterial meningitis and include fever, headache (often described as being frontal or retro-orbital), photophobia, pain upon moving the eyes, meningismus and sometimes a vesicular/petechial rash (rubella-like if echoviruses and coxsackieviruses are causative).

Constitutional symptoms-e.g., malaise, myalgia, anorexia, nausea, abdominal pain, diarrhea-may accompany fever. Mild lethargy is common. Occurrence of stupor, marked confusion or coma is rare, and these symptoms generally are not indicative of a meningitis with a viral cause. Gastrointestinal and respiratory symptoms may occur when infection is caused by enteroviruses.

The CSF profile is abnormal in viral meningitis. Characteristics include usually normal opening pressure, slightly increased protein and normal glucose (glucose is below normal for bacterial meningitis). The CSF leukocyte concentration is elevated with lymphocytic pleocytosis (polymorphonuclear neutrophils may predominate during the first 48 hours of meningitis, especially in some enteroviral infections). Bacteria are absent on Gram stain.

Mainstay of Treatment
Antimicrobial therapy is not effective for most viral agents; symptomatic therapy is the mainstay for treatment of most cases of viral meningitis. Hospitalization generally is not required, with case-specific exceptions, e.g., patients with deficient humoral immunity. Duration of illness is generally 10 days or less. Sequelae to viral meningitis, lasting a year or more, may include weakness, muscle spasm, insomnia and personality changes; paralysis is unusual although transient paresis and encephalitic manifestations may occur. Recovery from viral meningitis is usually complete for adults. The prognosis for infants and neonates is not as good-learning disabilities, hearing loss and other neurologic sequelae have been reported.

Because agent identification is often not done, difficult to determine or not available until after recovery, infection control is an important consideration. Enteroviruses are transmitted by the fecal-oral route and are among the more common causes of viral meningitis. The CDC recommends contact isolation in addition to Standard Precautions for neonates and young children diagnosed with enterovirus infection, including enteroviral meningitis. The National Institutes of Health Clinical Center practices a more conservative approach for management of meningitis with unclear etiology: Contact isolation is practiced for the duration of the illness for each patient diagnosed with aseptic meningitis. If a nonenteroviral diagnosis is established, infection control guidelines are then modified per the specific infectious agent identified. Generally, investigation of contacts or a source of infection is not indicated.

Case Study
Pending identification of the bacteria, D.F. is placed on droplet precautions and responds quickly to broad-spectrum antibiotic therapy. Droplet precautions are discontinued after 24 hours of antibiotic therapy and Standard Precautions alone are resumed. Culture results are positive for L. monocytogenes, a bacteria that is not transmitted person-to-person and for which antibiotic prophylaxis of contacts is not indicated. D.F. continues a speedy recovery.

Barbara Fahey is a nurse consultant with the Hospital Epidemiology Service, Office of the Director, Clinical Center, National Institutes of Health, Bethesda, MD.

Table 1: Most Common Agents Associated With Meningitis
Bacteria
Escherichia coli** Neisseria meningitidis*
Group B streptococci Pseudomonas species**
Haemophilus influenzae* Streptococcus pneumoniae*
Listeria monocytogenes*
Virus***
Adenovirus Echovirus
Herpes simplex Lymphocytic choriomeningitis virus
Arbovirus
Measles
Enteroviruses (picornaviruses)
Mumps
Coxsackievirus Varicella-zoster
* Can be normal oral pharyngeal flora. Conditions such as sinusitis, otitis media, upper respiratory tract infection, lower respiratory tract infection and trauma to the ears, nose or sinuses may predispose to nasopharyngeal epithelial cell infection, which in turn may result in bacteremia (transient or persistent), which in turn may result in bacteria traversing the blood-brain barrier into the CSF.
** Can be normal gastrointestinal flora. Entry into the central nervous system facilitated by trauma, neurosurgical procedures, lumbar puncture and spinal anesthesia.
*** Entry to body occurs via oral, oral-fecal or respiratory route. Virus replicates and spreads to brain via bloodstream.
Table 2: Cerebrospinal Fluid Analysis Findings
CSF Characteristic Normal Range Suggestive of Bacterial Meningitis Suggestive of Viral Meningitis
Color Clear Cloudy Cloudy
Red blood cell count None None None
Gram stain Negative Usually Positive Usually Negative (60%-90%)
Pressure Less than 200 mm H2O Above normal Normal
Protein 15-45 mg/dL Above normal Above normal
Glucose 50-75 mg/dL Below normal Usually normal or below normal
Lymphocytic pleocytosis None Positive with neutrophilic pleocytosis Positive with lymphocytic pleocytosis
Table 3: Predominant Bacterial Pathogens Causing Meningitis by Age Group
Age Group Bacterial Pathogen
Neonates Enteric bacteria
Gram-negative bacilli
Group B streptococci
Pseudomonas species
Listeria monocytogenes
Children
(> 1 month)
Haemophilis influenzae
Neisseria meningitidis
Adults bacilli* Meningococci species
Pneumococci species
Aerobic gram-negative
* Not as common as meningococci and pneumococci but identified with increasing frequency, especially among the elderly.

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