rabies

What is Rabies?

Rabies is a deadly viral disease that affects mammals, including humans. It is usually transmitted through the bite of an infected animal, typically dogs, but also other animals such as cats, bats, and raccoons.

• Transmission: The rabies virus is spread through the saliva of infected animals, which can enter the body through a bite or scratch [1].
• Symptoms: Initially, symptoms may be flu-like, including fever, muscle spasms, and lethargy. As the disease progresses, more severe symptoms such as seizures, hallucinations, and paralysis can occur [5][6].
• Zoonotic Disease: Rabies is a zoonotic disease, meaning it can pass between animals and humans [6].

Key Facts

• Vaccine-Preventable: Rabies is a vaccine-preventable disease, which means that prompt medical attention after exposure to the virus can prevent the development of symptoms [3].
• Fatal if Untreated: If left untreated, rabies is fatal in up to 99% of cases [4].
• Rabies Virus: The rabies virus is a negative-sense, non-segmented, single-stranded RNA virus measuring approximately 60 nm × 180 nm [7].

Important Information

• Prevention: The best way to prevent rabies is through vaccination and avoiding contact with infected animals.
• Symptoms: If you suspect you have been bitten or scratched by an animal that may be infected, seek medical attention immediately.

References: [1] - Context result 1 [2] - Context result 2 [3] - Context result 3 [4] - Context result 4 [5] - Context result 5 [6] - Context result 6 [7] - Context result 7

Rabies Signs and Symptoms

Rabies, a viral disease that affects the nervous system, can manifest in various ways. The initial symptoms are often similar to those of the flu, making it challenging to diagnose early on.

• Prodrome: The first symptoms of rabies may include weakness, discomfort, fever, or headache [1].
• Common Symptoms:
  • Fever
  • Headache
  • Nausea
  • Vomiting
  • Agitation
  • Anxiety
  • Confusion
  • Hyperactivity
  • Seizures
  • Hallucinations
  • Paralysis [2, 3]
• Initial Symptoms: The initial symptoms of rabies are similar to those of the flu - fever, headache, and generally feeling unwell [4].
• Advanced Symptoms: As the disease progresses, the person can experience anxiety, confusion, agitation, and hallucinations [5].
• Fatal Outcome: Once clinical signs of rabies appear, the disease is nearly always fatal [6].

Important Considerations

• Rabies should be considered in all cases of unexplained neurological symptoms or behavioral changes [7].
• The most common way to get rabies is through bat bites (in the U.S.) or dog bites (in Asia and other parts of the world) [4].

References:

[1] May 17, 2024 — [2] Symptoms · Fever · Headache · Nausea · Vomiting · Agitation · Anxiety · Confusion · Hyperactivity ... [3] Jun 5, 2024 — [4] It causes symptoms like seizures, hallucinations and paralysis. The most common way to get rabies is through bat bites (in the U.S.) or dog bites (in Asia and ... [5] The initial symptoms of rabies are similar to those of the flu - fever, headache, and generally feeling unwell. As the disease progresses, the person can ... [6] Jun 20, 2024 — [7] Although the most common signs of rabies are behavioral changes and unexplained paralysis, rabies should be considered in all cases of unexplained neurological ...

Diagnosing Rabies: A Comprehensive Overview

Rabies diagnosis involves several tests to confirm the presence of the virus in humans and animals. Here are some of the most widely used diagnostic tests for rabies:

• Fluorescent Antibody Test (FAT): This is a primary diagnostic test that detects the presence of rabies virus antigens in tissue samples. It's a highly sensitive and specific test, making it a reliable method for diagnosing rabies [1].
• Reverse Transcriptase Polymerase Chain Reaction (RT-PCR): This molecular test can detect the genetic material of the rabies virus in various biological samples, such as cerebrospinal fluid, saliva, or brain tissue. RT-PCR is a highly specific and sensitive method for diagnosing rabies [5].
• Direct Fluorescent Antibody Test (DFA): This test involves staining a brain impression smear with fluorescent antibodies to detect the presence of rabies virus antigens. DFA is a widely used test recommended by both WHO and OIE, making it a reliable method for diagnosing rabies [7].

Other diagnostic tests for rabies include:

• Flow Cytometry: This technique can be used to demonstrate the presence of rabies viral antigens in tissue samples.
• Fluorescent Antibody Virus Neutralization (FAVN) test: This test measures the response of an animal's immune system to the rabies vaccine, which can help diagnose rabies infection [10].

Key Points:

• No single test is sufficient for diagnosing rabies; multiple tests are necessary to confirm the presence of the virus.
• The FA test and DFA are widely used methods for diagnosing rabies in animals and humans.
• Molecular tests like RT-PCR can detect the genetic material of the rabies virus in various biological samples.

References:

[1] Context 2 [5] Context 5 [7] Context 7 [10] Context 10

Treatment Options for Rabies

Rabies treatment is typically focused on preventing the disease from developing after exposure, rather than treating it once symptoms appear. However, there are some experimental treatments and therapies that have been explored in recent years.

• Post-exposure prophylaxis (PEP): This involves administering human rabies immune globulin (HRIG) and a four-dose series of vaccines to prevent the disease from developing [1]. PEP is most effective when administered promptly after exposure.
• Broad-spectrum antiviral therapeutics: These have been used in conjunction with HRIG and RABV vaccine for highly aggressive rabies cases [3].
• Corticosteroids, minocycline, therapeutic coma, and prophylaxis of cerebral vasospasm: These are some of the other treatments that have been explored, but more research is needed to determine their effectiveness [4].

Experimental Treatments

Some experimental treatments have shown promise in treating rabies:

• Clofazimine (CFZ): This has been found to be efficacious against cerebral vasospasm with a low level of cytotoxicity [6].
• Other antiviral drugs: Research is ongoing to identify other antiviral drugs that may be effective against rabies.

Important Note

It's essential to note that there is no approved treatment for rabies once symptoms appear. Prompt medical attention and PEP are crucial in preventing the disease from developing after exposure.

References:

[1] Jun 20, 2024 — Rabies Post-exposure Prophylaxis (PEP) includes wound washing, human rabies immune globulin (HRIG), and a four-dose series of vaccines. [3] by V DuPont · 2019 · Cited by 42 — Administered in conjunction with RIG and RABV vaccine, broad-spectrum antiviral therapeutics are used for the treatment of highly aggressive rabies cases. [4] by AC Jackson · Cited by 3 — Outline · Corticosteroids · Minocycline · Therapeutic coma · Prophylaxis of cerebral vasospasm. [6] by J Wu · 2021 · Cited by 7 — Clofazimine (CFZ) was found to be efficacious against CVS with an EC50 value of 2.28 μM, and a low level of cytotoxicity (SI of >967).

Differential Diagnosis of Rabies

Rabies, a viral infection caused by a bite from an infected animal, can be challenging to diagnose due to its varied clinical presentation and lack of exposure history [8]. However, there are several conditions that should be considered in the differential diagnosis of rabies.

Conditions to Consider:

• Botulism: A rare but serious illness caused by a toxin produced by the bacteria Clostridium botulinum. Symptoms include muscle weakness, paralysis, and respiratory failure [1].
• Encephalitis: Inflammation of the brain, which can be caused by various viruses, bacteria, or other pathogens. Rabies should be considered in patients with encephalitis of unknown origin, particularly if there is a history of animal exposure [5].
• Guillain-Barre Syndrome: A rare autoimmune disorder that occurs when the body's immune system mistakenly attacks part of its peripheral nervous system. Symptoms include muscle weakness and paralysis [1].
• Herpes Simplex: A viral infection caused by the herpes simplex virus, which can cause encephalitis in severe cases [6].
• Poliomyelitis: A highly infectious disease caused by the poliovirus, which can lead to paralysis and other neurological symptoms [1].

Clinical Signs and Symptoms:

Rabies should be considered in patients with unexplained, acute, progressive viral encephalitis, even if there is no history of animal exposure [3]. Clinical signs and symptoms that may suggest rabies include:

• Abnormal behavior
• Inability to swallow
• Lameness
• Central nervous system abnormalities

Laboratory Findings:

While laboratory findings are not definitive for rabies diagnosis, they can support the clinical suspicion. These findings may include:

• Encephalitis on imaging studies
• Laboratory evidence of viral infection (e.g., PCR or serology)
• Histopathological examination of brain tissue (in post-mortem cases)

Prioritization of Differential Diagnoses:

Clinical suspicion and prioritization of differential diagnoses can be complicated by variations in clinical presentation and a lack of exposure history [7]. Therefore, it is essential to consider rabies as part of the differential diagnosis for patients presenting with unexplained encephalitis or other neurological symptoms.

References:

[1] Mar 7, 2024 - Differential Diagnoses · Botulism · Encephalitis · Guillain-Barre Syndrome · Herpes Simplex · Herpes Simplex Encephalitis · Poliomyelitis. [2] Diagnosis. Differential Diagnosis. The diagnosis of human rabies is usually suggested by epidemiologic and clinical findings and confirmed in the laboratory. [3] However, rabies should be included in the differential diagnosis of all patients who present with unexplained, acute, progressive viral encephalitis, even in ... [4] Rabies should always be considered as a differential diagnosis for clinical signs related to the CNS. Diagnosis based on clinical signs alone should not be ... [5] May 17, 2024 — Rabies causes encephalitis in infected patients. Rabies should be considered in patients with encephalitis of unknown origin, particularly if ... [6] Jun 14, 2024 — Outline · Prodromal symptoms · Clinical rabies · - Encephalitic rabies · - Paralytic rabies · Complications · Laboratory findings · Imaging. [7] Clinical suspicion and prioritization of differential diagnoses can be complicated by variations in clinical presentation and a lack of exposure history, ... [8] Rabies is a viral infection that primarily spreadsTrusted Source through a bite from an infected animal. Without early treatment, it is usually fatal. [9] Rabies should be on the differential diagnosis list for: abnormal behavior, inability to swallow, lameness, and central nervous system abnormalities. · Rabies ...