How do you test for brain infection?

There are a variety of tests that doctors can use to diagnose brain infections. The specific tests used will depend on the patient’s symptoms and what type of infection is suspected. Some common tests for brain infections include:

Blood Tests

Blood tests look for signs of infection in the blood and can help identify the type of infection. They can check for:

  • White blood cell count – High white blood cell counts often indicate an infection.
  • C-reactive protein (CRP) – Levels of this protein go up when there is inflammation.
  • Erythrocyte sedimentation rate (ESR) – This blood test indicates inflammation.
  • Blood cultures – Growth of bacteria or fungi indicates blood infection.

Imaging Tests

Imaging scans allow doctors to see inside the brain and look for signs of infection or inflammation. Common brain imaging tests include:

  • MRI – Magnetic resonance imaging provides detailed images of the brain. It can detect swelling, abscesses, and other signs of infection.
  • CT scan – Computed tomography scans use x-rays and computers to create cross-sectional images of the brain.
  • PET scan – A positron emission tomography scan uses radioactive tracers to see how tissues are functioning.
  • Angiogram – This images the blood vessels in the brain.

Lumbar Puncture

A lumbar puncture, also called a spinal tap, is a procedure where a needle is inserted between two vertebrae in the lower spine to collect a sample of cerebrospinal fluid (CSF). The CSF is tested for:

  • Cell count – High white blood cells indicate inflammation.
  • Protein levels – Increased proteins suggest infection.
  • Glucose level – Low glucose may mean an infection.
  • Bacteria or fungi – Finding microorganisms indicates infection.

Brain Biopsy

In some cases, a small sample of brain tissue may be taken for biopsy. Examining the brain tissue can definitively diagnose certain infections, cancers, and other conditions. This procedure has risks since it involves surgery and entering the skull.

Who gets tested for brain infections?

Testing is done when someone has symptoms that indicate a possible brain infection. Some red flags include:

  • Headaches
  • Mental confusion
  • Fever
  • Stiff neck
  • Nausea/vomiting
  • Sleepiness
  • Seizures
  • Loss of balance
  • Weakness or numbness
  • Vision changes

People at higher risk of brain infections who may need screening include:

  • Those with a weakened immune system from HIV, chemotherapy, etc.
  • Patients who recently had neurosurgery or invasive procedures
  • Intravenous drug users
  • Infants with high fevers
  • Elderly

Types of Brain Infections

There are different categories of infections that can affect the brain and central nervous system:

Bacterial Infections

  • Meningitis – Inflammation of the membranes surrounding the brain, often caused by bacteria like Streptococcus, Neisseria meningitidis, Haemophilus influenzae, Listeria.
  • Brain abscess – Pocket of pus caused by bacterial infection, like Staphylococcus aureus.
  • Encephalitis – Inflammation of the brain tissue itself, which can result from untreated meningitis or spread of infection through blood.
  • Neurosyphilis – Late stage syphilis infection affecting the brain and nervous system.

Viral Infections

  • Meningitis – Caused by viruses like enterovirus, herpes simplex virus, varicella zoster.
  • Encephalitis – Swelling of the brain due to viruses including herpes simplex, rabies, mumps, measles.
  • HIV encephalopathy – Brain dysfunction and cognitive decline due to HIV infection.

Fungal Infections

  • Meningitis – Cryptococcus, Candida, and other fungi can cause meningitis.
  • Abscesses – Fungal brain abscesses are rare but can be caused by Candida, Aspergillus, Cryptococcus neoformans, Coccidioides immitis.

Parasitic Infections

  • Neurocysticercosis – Parasitic infection of the brain caused by larval cysts of the pork tapeworm Taenia solium.
  • Toxoplasmosis – Infection by the Toxoplasma gondii parasite, often caught from cats.
  • Malaria – The Plasmodium parasite can infect red blood cells and travel to the brain causing cerebral malaria.
  • Amebic meningoencephalitis – Rare condition caused by the ameba Naegleria fowleri.

Brain Infection Symptoms

Infections in the brain can cause a wide range of neurological symptoms that depend on the part of the brain affected. Common symptoms include:

  • Headache – Often severe.
  • Fever and chills
  • Stiff neck
  • Nausea and vomiting
  • Confusion and memory loss
  • Personality changes
  • Seizures
  • Weakness or numbness on one side of the body
  • Difficulty walking or balancing
  • Vision changes like blurred or double vision
  • Sensitivity to light
  • Speech problems
  • Hearing loss
  • Loss of consciousness

In infants, symptoms may include high fever, bulging soft spots on the head, stiffness, seizures, and poor feeding.

When to See a Doctor

Seek emergency medical care right away if you experience any of the following:

  • Sudden, severe headache
  • High fever
  • Stiff neck
  • Rash or purple spots on the skin
  • Confusion
  • Seizures
  • Difficulty walking or speaking
  • Loss of vision
  • Extreme drowsiness

Call your doctor if you have milder symptoms like headache, fatigue, nausea, mild fever, memory problems or personality changes. Prompt treatment is needed to prevent serious complications.

Brain Infection Causes

Brain infections are typically caused by one of the following:

  • Bacteria – Streptococcus, Neisseria meningitidis, Listeria, mycobacteria.
  • Viruses – Herpes simplex, varicella zoster, mumps, measles, rabies.
  • Fungi – Cryptococcus, Candida, Aspergillus.
  • Parasites – Cysticercosis, toxoplasmosis, malaria.

Infections reach the brain through:

  • Blood – Bacteria or viruses in the blood cross the blood-brain barrier.
  • Nerves – Some viruses travel along cranial or peripheral nerves.
  • Ears/sinuses – Infections can spread from middle ear, mastoids or nasal sinuses.
  • Skull defects – Openings after injury or surgery can expose the brain to infection.
  • Foreign objects – Contaminated objects that penetrate the skull can introduce infection.

Risk factors that make people more susceptible include:

  • HIV/AIDS and other conditions that weaken the immune system
  • Cancer and chemotherapy treatment
  • Organ transplant anti-rejection medications
  • Autoimmune disorders
  • Diabetes
  • Head trauma or neurosurgery
  • Shunts to drain spinal fluid
  • History of meningitis
  • Living in close quarters
  • Smoking and alcohol abuse
  • Cochlear implants

How Are Brain Infections Diagnosed?

If symptoms indicate a possible brain infection, tests will be done to diagnose the type of infection and determine the best treatment. These may include:

  • Medical history – The doctor will ask about symptoms, risk factors, recent illnesses or travel.
  • Physical exam – Check for fever, neck stiffness, neurological abnormalities, and changes in mental function.
  • Blood tests – Can show high white cell count, antibodies, or organisms causing infection.
  • Spinal tap – Looks for bacteria and abnormal cell counts in cerebrospinal fluid.
  • Imaging tests – CT, MRI, or angiogram detects brain changes like inflammation, bleeding or swelling.
  • EEG – Records electrical activity in the brain, may show seizure activity.
  • Biopsy – Rarely done, involves removing a small brain tissue sample to identify organisms.

These tests help doctors determine if there is an infection and what is causing it so the most effective antibiotic or antiviral medication can be prescribed.

Brain Infection Treatment

Treatment focuses on eliminating the infection with medications and reducing complications:

  • Antibiotics – Used to treat bacterial infections of the brain and nervous system like meningitis. Often given intravenously in hospital.
  • Antivirals – Treat viral infections. May help with encephalitis from herpes simplex.
  • Antifungals – Used for fungal infections like cryptococcal meningitis. Amphotericin B is commonly used.
  • Corticosteroids – Helps reduce swelling, often used with antibiotics and antivirals.
  • Seizure medications – Used to control seizures that may result from inflammation in the brain.
  • ICP monitoring – For severe infections, intracranial pressure is measured and managed.
  • Surgery – May be needed to remove abscesses or drain blood/pus.

In the hospital, patients are closely monitored for complications like sepsis or brain damage. Supportive treatment aims to keep normal fluid levels, blood pressure and oxygenation.

Are Brain Infections Contagious?

Many types of brain infections are contagious and can spread from person to person. Bacterial and viral meningitis are very contagious. Fungal infections like cryptococcosis are generally not contagious between people.

Brain infections often spread through:

  • Coughing or sneezing droplets from an infected person.
  • Touching surfaces contaminated with viruses or bacteria then touching your face.
  • Sharing food or drinking glasses with someone who is ill.
  • Kissing an infected person.

To prevent transmission:

  • Cover coughs and sneezes. Have ill individuals wear a mask.
  • Practice good hand hygiene by washing regularly.
  • Disinfect surfaces like doorknobs, phones, keyboards.
  • Avoid sharing personal items like water bottles or utensils.
  • Get recommended vaccines – flul, haemophilus, pneumococcal, meningococcal.

Those in close contact with someone diagnosed with a contagious brain infection will likely receive preventative antibiotics.

Are Brain Infections Serious?

Yes, infections in the brain and central nervous system can be very serious if not treated promptly. Complications can include:

  • Sepsis – Blood infection that can become life threatening.
  • Brain damage – Permanent injury to the brain from inflammation and swelling.
  • Hearing loss or blindness.
  • Learning disabilities.
  • Speech impairments.
  • Paralysis.
  • Seizure disorders.
  • Coma.
  • Death – Meningitis has a mortality rate around 15%, encephalitis around 7%. Higher in infants.

Even with treatment, some patients develop long-term neurological problems. Seek emergency treatment immediately if meningitis or encephalitis is suspected.

Preventing Brain Infections

You can take these steps to reduce the chances of developing a brain infection:

  • Get recommended vaccines – pneumococcal, haemophilus, meningococcal, flu, measles.
  • Wash hands well and often, especially before eating and after using the bathroom.
  • Don’t share drinks, utensils, cigarettes or makeup with others.
  • Clean and cover any cuts, abrasions or burns right away.
  • Avoid contact with wild animals that may carry rabies.
  • Use insect repellent and nets in malaria risk regions.
  • Cook meat thoroughly and avoid raw milk products.
  • Avoid cat feces during pregnancy to prevent toxoplasmosis.
  • Practice safe sex and get tested for STDs that can cause neurosyphilis.

Those at higher risk, like the elderly or immunocompromised patients, need to be extra vigilant.

Conclusion

Infections of the brain can be very serious, even fatal. Bacterial and viral meningitis, encephalitis, brain abscesses and other infections require prompt medical attention and often hospitalization. Diagnostic tests like imaging, spinal taps and EEG along with blood work help identify the type of infection so that appropriate antibiotics, antivirals and other treatments can be started rapidly. With early treatment, complications can often be minimized and outcomes improved. Preventing spread of contagious brain infections also remains crucial.

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