Rabies Virus

Rabies virus is a single-stranded, negative-sense RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure virus. This bullet-shaped virus belongs to the family Rhabdoviridae and the genus Lyssavirus. Rabies is a preventable disease most often transmitted to humans through the bite of an infected animal (e.g., bats, raccoons, skunks, and foxes). This life-threatening disease affects the CNS, resulting in severe neurologic manifestations. There are 5 stages of disease in humans: incubation, prodrome, acute neurologic period, coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma, and death. The diagnosis is made with antibody, antigen, or viral RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure detection in tissue biopsy, serum, CSF, and saliva. There is no effective treatment for symptomatic disease, so prevention with human rabies immunoglobulin and vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination is the mainstay of management.

Last update:

Editorial responsibility: Stanley Oiseth, Lindsay Jones, Evelin Maza

Table of Contents

Share this concept:

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on email
Share on whatsapp

Classification

Rna viruses flowchart classification

RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure virus identification:
Viruses can be classified in many ways. Most viruses, however, will have a genome formed by either DNA DNA The molecule DNA is the repository of heritable genetic information. In humans, DNA is contained in 23 chromosome pairs within the nucleus. The molecule provides the basic template for replication of genetic information, RNA transcription, and protein biosynthesis to promote cellular function and survival. DNA Types and Structure or RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure. RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure genome viruses can be further characterized by either a single- or double-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure. “Enveloped” viruses are covered by a thin coat of cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane (usually taken from the host cell). If the coat is absent, the viruses are called “naked” viruses. Viruses with single-stranded genomes are “positive-sense” viruses if the genome is directly employed as messenger RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure (mRNA), which is translated into proteins. “Negative-sense,” single-stranded viruses employ RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure dependent RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure polymerase, a viral enzyme, to transcribe their genome into messenger RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure.

Image by Lecturio. License: CC BY-NC-SA 4.0

General Characteristics and Epidemiology

Basic features of rabies virus

  • Taxonomy:
    • Family: Rhabdoviridae
    • Genus: Lyssavirus
  • Midsize:
    • 180 nm long
    • 75 nm wide
  • RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure genome:
    • Single-stranded
    • Linear
    • Negative-sense
  • Structure:
    • Bullet-shaped
    • Helical ribonucleoprotein core
    • Enveloped
    • Glycoprotein spikes on the virus surface
  • Carries RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure-dependent RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure polymerase (RDRP)

Associated disease

Rabies virus causes the disease rabies.

Epidemiology

  • Rabies is present in nearly every country.
    • Developing countries are more affected:
      • Asia
      • Africa
      • Latin America
    • Animal vaccinations in the United States and Europe have largely eliminated rabies in domestic animals. 
  • Approximately 59,000 deaths each year worldwide
  • 2–3 cases per year in the United States
  • Children (boys > girls) are 4 times as likely as adults to get rabies.

Pathogenesis

Reservoir

Mammalian species serve as hosts. In the United States, these may include:

  • Bat
  • Skunk
  • Raccoon
  • Fox
  • Mongoose
  • Coyote
  • Wolf
  • Unvaccinated dogs

Transmission

Human infection is almost always due to a bite by an infected mammal.

  • Most common: saliva of infected animals
  • Rare:
    • Organ transplant
    • Transplacental
    • Inhalation of aerosolized virus

Host risk factors

Susceptibility to lethal infection is related to:

  • Animal species
  • Viral variant
  • Inoculum concentration
  • Location of exposure
    • Head and neck bite versus distal body part
    • Amount of innervation at the bite site
  • Severity of exposure
  • Host immune status

Viral replication cycle

  • Rabies virus binds to receptors on outside host cells → enters host cells by the endosomal transport pathway 
  • ↓ pH in the endosome causes membrane fusion → viral genome reaches the cytosol → viral RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure uncoats in the cytoplasm of infected cells 
  • Genome transcription Transcription Transcription of genetic information is the first step in gene expression. Transcription is the process by which DNA is used as a template to make mRNA. This process is divided into 3 stages: initiation, elongation, and termination. Stages of Transcription by a virion-associated RDRP →  viral RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure is translated into viral proteins 
  • Replication occurs with synthesis of positive-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure templates for the production of negative-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure.
  • Virions are assembled → virus buds from the cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane
Rabies virus life cycle

Rabies virus replication cycle

Image by Lecturio. License: CC BY-NC-SA 4.0

Pathophysiology

  • Inoculation → virus has predilection for neural tissue → enters local motor and sensory nerves
  • Travels via peripheral nerves → migrates to the spinal cord Spinal cord The spinal cord is the major conduction pathway connecting the brain to the body; it is part of the CNS. In cross section, the spinal cord is divided into an H-shaped area of gray matter (consisting of synapsing neuronal cell bodies) and a surrounding area of white matter (consisting of ascending and descending tracts of myelinated axons). Spinal Cord → brain
  • Mechanism for encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis is unclear.
  • Spreads back through peripheral nerves → disseminates to other parts of the body

Clinical Presentation

5 general stages are recognized in humans: incubation → prodrome → acute neurologic period → coma Coma Coma is defined as a deep state of unarousable unresponsiveness, characterized by a score of 3 points on the GCS. A comatose state can be caused by a multitude of conditions, making the precise epidemiology and prognosis of coma difficult to determine. Coma → death

Incubation

  • Variable Variable Variables represent information about something that can change. The design of the measurement scales, or of the methods for obtaining information, will determine the data gathered and the characteristics of that data. As a result, a variable can be qualitative or quantitative, and may be further classified into subgroups. Types of Variables from 10 days–2 years, but usually 20–90 days
  • Shorter in children and with bites closer to the CNS

Prodrome

  • Prodromal period lasts 0–10 days.
  • Symptoms are nonspecific
    • General malaise
    • Fever
    • Fatigue
    • Sore throat
    • Cough
    • Dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea
    • Nausea and vomiting
    • Headache
    • Pain or paresthesias Paresthesias Subjective cutaneous sensations (e.g., cold, warmth, tingling, pressure, etc.) that are experienced spontaneously in the absence of stimulation. Respiratory Alkalosis at the bite site

Acute neurologic period

Acute neurologic period lasts 2–7 days.

Encephalitic form (most common):

  • Hyperactivity and agitation
  • Altered mental status
    • Confusion
    • Hallucinations
  • Pharyngeal muscle spasms
    • Hydrophobia 
    • Aerophobia
    • Choking
    • Coughing
  • Nuchal rigidity
  • Muscle fasciculations and contractions
    • Facial grimacing
    • Back and neck hyperextension
  • Increased deep tendon reflexes
  • Autonomic instability
    • Hypersalivation
    • Sweating
    • Lacrimation
    • Pupil Pupil The pupil is the space within the eye that permits light to project onto the retina. Anatomically located in front of the lens, the pupil's size is controlled by the surrounding iris. The pupil provides insight into the function of the central and autonomic nervous systems. Physiology and Abnormalities of the Pupil dilation
    • Fever
    • Tachycardia
  • Seizures

Paralytic form:

  • Fever
  • Headache
  • Ascending, flaccid paralysis
  • Muscle fasciculations
  • Absent deep tendon reflexes
  • Bladder dysfunction
Man with rabies virus

A man with rabies in 1959.

Image: “Rabies patient” by CDC. License: Public Domain

Coma

  • Unresponsive
  • Periods of rapid, irregular breathing
  • Apnea
  • Paralysis

Death

  • Death usually occurs 2–14 days after 1st symptoms appear.
  • Often results from:
    • Respiratory arrest
    • Uncontrolled seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures
    • Cardiac arrhythmias

Diagnosis and Management

Diagnosis

The diagnosis should be suspected in cases of unexplained viral encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis with a history of an animal bite. 

Diagnostic methods:

  • Antibody titers
  • PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) to detect viral RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure
  • Isolation of virus (viral culture)
  • Immunofluorescent staining of biopsy specimens for viral antigen

Specimens that can be tested:

  • Saliva
  • CSF
  • Serum
  • Tissue ( skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Structure and Function of the Skin from the nape of the neck or brain)

Management

There is no effective treatment for symptomatic rabies, and few patients survive.

  • Palliative care
  • Life support measures can prolong the clinical course but rarely affect the outcome.

Prevention

Prevention is the mainstay of care.

  • Vaccinate susceptible species (dogs and cats).
  • Preexposure prophylaxis with rabies vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination is indicated for:
    • Travel to endemic areas
    • Veterinarians
    • Animal handlers
  • Postexposure prophylaxis:
    • Local wound cleaning
    • Human rabies immune globulin (HRIG)
      • Given only once to previously unvaccinated people.
      • Provides immediate antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins
      • Inject as much as possible at the bite site (infiltrate into the wounds).
      • Remaining volume should be injected IM at a site distant from vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination administration
    • Rabies vaccine Vaccine A vaccine is usually an antigenic, non-virulent form of a normally virulent microorganism. Vaccinations are a form of primary prevention and are the most effective form due to their safety, efficacy, low cost, and easy access. Vaccination:
      • 1st dose given as soon as possible after exposure. 
      • Additional doses are given on days 3, 7, and 14 after the 1st vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination.

Differential Diagnosis

  • Bacterial meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis: acute infection of the meninges Meninges The brain and the spinal cord are enveloped by 3 overlapping layers of connective tissue called the meninges. The layers are, from the most external layer to the most internal layer, the dura mater, arachnoid mater, and pia mater. Between these layers are 3 potential spaces called the epidural, subdural, and subarachnoid spaces. Meninges. Patients present with headache, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, nuchal rigidity, and rapid clinical deterioration. A lumbar puncture is performed to make the diagnosis. Unlike with viral meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis, CSF studies will show a turbid fluid, low glucose, and high WBC with neutrophil predominance. Gram stain and culture will determine the causative bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview. Treatment includes antibiotics and corticosteroids.
  • Herpes simplex encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis: severe CNS infection caused by herpes simplex viruses. Patients develop rapid onset of fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, headache, altered level of consciousness, focal neurologic deficits, and seizures Seizures A seizure is abnormal electrical activity of the neurons in the cerebral cortex that can manifest in numerous ways depending on the region of the brain affected. Seizures consist of a sudden imbalance that occurs between the excitatory and inhibitory signals in cortical neurons, creating a net excitation. The 2 major classes of seizures are focal and generalized. Seizures. The diagnosis is confirmed with PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) testing of CSF. MRI may show hyperintense lesions in the temporal lobes. IV acyclovir is the treatment of choice.
  • Tick-borne encephalitis virus Tick-borne Encephalitis Virus Tick-borne encephalitis virus (TBEV) is a positive-sense, single-stranded RNA virus of the genus Flavivirus. Transmission occurs primarily via Ixodes ticks found in Europe, the former Soviet Union, and Asia. The virus causes tick-borne encephalitis. Most patients are asymptomatic; however, symptomatic individuals may experience a biphasic illness. Tick-borne Encephalitis Virus: member of the genus Flavivirus transmitted primarily by Ixodes ticks. Most patients infected with with tick-borne encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis virus are asymptomatic; however, symptomatic individuals may experience a biphasic illness. After recovering from nonspecific symptoms, patients can develop neurologic manifestations, such as meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis, encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis, or meningoencephalitis. Serology or PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR) can confirm the diagnosis. Management is supportive. 
  • West Nile virus West Nile Virus West Nile virus is an enveloped, positive-sense, single-stranded RNA virus of the genus Flavivirus. Birds are the primary hosts and the disease is most often transmitted by Culex mosquitoes. Most people infected with West Nile virus are asymptomatic. Some patients develop West Nile fever (a self-limited, febrile illness) and a very small proportion of patients develop West Nile neuroinvasive disease. West Nile Virus: member of the genus Flavivirus transmitted by Culex mosquitoes. Most patients infected with West Nile virus West Nile Virus West Nile virus is an enveloped, positive-sense, single-stranded RNA virus of the genus Flavivirus. Birds are the primary hosts and the disease is most often transmitted by Culex mosquitoes. Most people infected with West Nile virus are asymptomatic. Some patients develop West Nile fever (a self-limited, febrile illness) and a very small proportion of patients develop West Nile neuroinvasive disease. West Nile Virus are asymptomatic. A very small proportion of patients develop neuroinvasive disease, which includes meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis, encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis, and acute flaccid paralysis. The diagnosis is confirmed with serum or CSF serology or PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR). Management is supportive. 
  • Saint Louis encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis virus: member of the genus Flavivirus transmitted by Culex mosquitoes. Symptomatic individuals may have varied presentations, with flu-like symptoms, aseptic meningitis Meningitis Meningitis is inflammation of the meninges, the protective membranes of the brain, and spinal cord. The causes of meningitis are varied, with the most common being bacterial or viral infection. The classic presentation of meningitis is a triad of fever, altered mental status, and nuchal rigidity. Meningitis, encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis, or meningoencephalitis. Diagnosis is confirmed with serology. Management is supportive.
  • Equine encephalitis viruses Equine Encephalitis Viruses Equine encephalitis viruses (EEVs), belonging to the Togaviridae family and Alphavirus genus, are mosquito-borne arboviruses that infect humans and cause minor illness or, in severe cases, encephalitis. The eastern equine encephalitis (EEE) virus complex consists of the EEE virus, Madariaga virus, western EEV, and Venezuelan EEV. Equine Encephalitis Viruses: members of the family Togaviridae. The equine encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis viruses are mosquito-borne arboviruses that can cause minor viral illness or encephalitis Encephalitis Encephalitis is inflammation of the brain parenchyma caused by an infection, usually viral. Encephalitis may present with mild symptoms such as headache, fever, fatigue, and muscle and joint pain or with severe symptoms such as seizures, altered consciousness, and paralysis. Encephalitis (in severe cases). Diagnosis is by CSF evaluation, serology, or PCR PCR Polymerase chain reaction (PCR) is a technique that amplifies DNA fragments exponentially for analysis. The process is highly specific, allowing for the targeting of specific genomic sequences, even with minuscule sample amounts. The PCR cycles multiple times through 3 phases: denaturation of the template DNA, annealing of a specific primer to the individual DNA strands, and synthesis/elongation of new DNA molecules. Polymerase Chain Reaction (PCR). Management is supportive.
  • Guillain-Barré syndrome Guillain-Barré syndrome Guillain-Barré syndrome (GBS), once thought to be a single disease process, is a family of immune-mediated polyneuropathies that occur after infections (e.g., with Campylobacter jejuni). Guillain-Barré Syndrome (GBS): acute, rapidly progressive, acquired inflammatory neuropathy that can be triggered by infectious pathogens. Patients develop progressive, symmetric muscle weakness and sensory loss. Unlike rabies, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever is rare in GBS. The diagnosis is clinical. A lumbar puncture will show a normal cell count and elevated protein. Management requires intensive care support, IV immune globulin, and plasma exchange.
  • Botulism Botulism Botulism is a rare, neuroparalytic syndrome caused by Clostridium botulinum (C. botulinum). A fatal neurotoxin (botulinum toxin) is released causing varying degrees of muscle paralysis and distinct clinical syndromes. The most common types of botulism are foodborne and infant. Botulism: rare, neuroparalytic syndrome caused by a neurotoxin released from Clostridium botulinum. Botulism Botulism Botulism is a rare, neuroparalytic syndrome caused by Clostridium botulinum (C. botulinum). A fatal neurotoxin (botulinum toxin) is released causing varying degrees of muscle paralysis and distinct clinical syndromes. The most common types of botulism are foodborne and infant. Botulism presents with blurred vision, respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure, and symmetric, descending flaccid paralysis. Unlike rabies, fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever is absent. Diagnosis is made on clinical grounds and can be confirmed by the isolation of bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology: Overview or toxins from stool, wound specimens, or food sources. Treatment requires prompt management of respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure, administration of antitoxin, and supportive care for paralysis.
  • Tetanus Tetanus Tetanus is a bacterial infection caused by Clostridium tetani, a gram-positive obligate anaerobic bacterium commonly found in soil that enters the body through a contaminated wound. C. tetani produces a neurotoxin that blocks the release of inhibitory neurotransmitters and causes prolonged tonic muscle contractions. Tetanus: bacterial infection caused by Clostridium tetani, a gram-positive obligate anaerobic bacterium commonly found in soil that enters the body through a contaminated wound. Tetanus Tetanus Tetanus is a bacterial infection caused by Clostridium tetani, a gram-positive obligate anaerobic bacterium commonly found in soil that enters the body through a contaminated wound. C. tetani produces a neurotoxin that blocks the release of inhibitory neurotransmitters and causes prolonged tonic muscle contractions. Tetanus presents with lockjaw, neck stiffness, opisthotonus, rigid abdomen, and severe, painful muscle spasms. Diagnosis is made on clinical grounds, as it is rarely possible to isolate the infectious agent from the wound. Tetanus Tetanus Tetanus is a bacterial infection caused by Clostridium tetani, a gram-positive obligate anaerobic bacterium commonly found in soil that enters the body through a contaminated wound. C. tetani produces a neurotoxin that blocks the release of inhibitory neurotransmitters and causes prolonged tonic muscle contractions. Tetanus is treated with antibiotic therapy and the human tetanus antitoxin.

References:

  1. Baron, S., Rupprecht, C. (1996). Rhabdoviruses: rabies virus. Chapter 61 of Medical microbiology, 4th ed. University of Texas Medical Branch at Galveston.  
  2. Centers for Disease Control: Rabies prevention (1991). Recommendations of the Immunization Practices Advisory Committee (ACIP). MMWR 40(RR-3):1.
  3. Centers for Disease Control: Compendium of animal rabies control (1995). MMWR 44(RR-2):1.
  4. Centers for Disease Control: Human rabies (1995). MMWR 44:269.
  5. Charlton KM. (1994). The pathogenesis of rabies and other lyssaviral infections: recent studies. Curr Top Microbiol Immunol 187:95.
  6. DeMaria, A., Jr., Brown, C. (2020). Clinical manifestations and diagnosis of rabies. UpToDate. Retrieved May 10, 2021, from https://www.uptodate.com/contents/clinical-manifestations-and-diagnosis-of-rabies
  7. Brown, C.M., DeMaria, A., Jr. (2020). When to use rabies prophylaxis. UpToDate. Retrieved May 16, 2021, from https://www.uptodate.com/contents/when-to-use-rabies-prophylaxis
  8. Jackson, A.C. (2021). Treatment of rabies. UpToDate. Retrieved May 16, 2021, from  https://www.uptodate.com/contents/treatment-of-rabies
  9. Koury, R., Warrington, S.J. (2020). Rabies. [online] StatPearls. Retrieved May 16, 2021, from https://www.ncbi.nlm.nih.gov/books/NBK448076/
  10. Greenlee, J.E. (2020). Rabies. MSD Manual Professional Version. https://www.msdmanuals.com/professional/neurologic-disorders/brain-infections/rabies
  11. Gompf, S. (2019). Rabies. Emedicine. Retrieved May 10, 2021, from: https://emedicine.medscape.com/article/220967-overview

USMLE™ is a joint program of the Federation of State Medical Boards (FSMB®) and National Board of Medical Examiners (NBME®). MCAT is a registered trademark of the Association of American Medical Colleges (AAMC). NCLEX®, NCLEX-RN®, and NCLEX-PN® are registered trademarks of the National Council of State Boards of Nursing, Inc (NCSBN®). None of the trademark holders are endorsed by nor affiliated with Lecturio.

Study on the Go

Lecturio Medical complements your studies with evidence-based learning strategies, video lectures, quiz questions, and more – all combined in one easy-to-use resource.

Learn even more with Lecturio:

Complement your med school studies with Lecturio’s all-in-one study companion, delivered with evidence-based learning strategies.

User Reviews

0.0

()

¡Hola!

Esta página está disponible en Español.

🍪 Lecturio is using cookies to improve your user experience. By continuing use of our service you agree upon our Data Privacy Statement.

Details