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vaccinia
Description
Vaccinia Virus: A Complex Enveloped Virus
The vaccinia virus (VACV or VV) is a large, complex, enveloped virus belonging to the poxvirus family [1]. It has a linear, double-stranded DNA genome approximately 190 kbp in length, which encodes approximately 250 genes [2]. The dimensions of the virion are roughly 360 × 270 × 250 nm, with a mass of approximately 5–10 fg [3].
Key Characteristics
- Enveloped virus: Vaccinia virus has a lipid envelope that surrounds its protein coat.
- Double-stranded DNA genome: The virus's genetic material is composed of two complementary strands of DNA.
- Large and complex: Vaccinia virus is one of the largest viruses, with a genome size comparable to that of some bacteria.
Relation to Smallpox
The vaccinia virus is closely related to variola major, the virus that causes smallpox [11]. In fact, exposure to vaccinia provides cross-immunity against smallpox, making it an effective vaccine against this disease. The smallpox vaccine is highly effective in preventing infection, with protection lasting about three to five years [11].
Other Facts
- Vaccinia virus has been used for vaccination for more than 100 years [13].
- It played a crucial role in eradicating smallpox in the late 1970s [8].
- The virus is the source of the modern smallpox vaccine, which was instrumental in global smallpox eradication efforts [1].
References: [1] - Context result 1 [2] - Context result 1 [3] - Context result 1 [11] - Context result 11 [13] - Context result 13 [8] - Context result 8
Additional Characteristics
- enveloped virus
- double-stranded DNA genome
- large and complex
- effective vaccine against smallpox
- instrumental in global smallpox eradication efforts
Signs and Symptoms
Common Signs and Symptoms of Vaccinia Infection
Vaccinia infection, also known as smallpox or cowpox, can manifest in various ways, depending on the severity of the disease. Here are some common signs and symptoms:
- Fever: A high temperature, usually above 101°F (38.3°C), is a common initial symptom of vaccinia infection [1].
- Rash: A characteristic rash, often accompanied by redness and swelling, can appear on the skin, typically at the site of vaccination or in other areas [2-4].
- Lymphadenopathy: Swelling and tenderness of lymph nodes, particularly in the axillary region, can occur 3-10 days after vaccination [2].
- Fatigue: Feeling tired or exhausted is a common symptom, often accompanied by general symptoms similar to those of a cold [1].
- Headaches: Headaches, myalgias (muscle pain), and fatigue are also common symptoms in some patients [5].
In more severe cases, vaccinia infection can lead to:
- Eczema vaccinatum: A serious rash caused by widespread infection of the skin [6].
- Vaccinia disease: Can present in a variety of manifestations along a spectrum ranging from mild, localized disease to severe systemic illness [9].
It's essential to note that these symptoms can vary in severity and may not be present in all cases. If you suspect vaccinia infection or any other vaccine-related side effects, consult a healthcare professional for proper evaluation and treatment.
References:
[1] DCM Silva (2010) - The initial clinical signs of the infection are focal red skin areas, fever, and general symptoms similar to those of a cold. [2] In addition to a lesion at the site of vaccination, vaccination can produce swelling and tenderness of axillary and other lymph nodes, beginning 3 - 10 days... [3] Oct 1, 2019 — This is characterized by fever, headache, myalgias, and fatigue. Research suggests that a person's risk of developing fever following... [4] Signs and Symptoms. The vaccination is accompanied by fever, rash, lymphadenopathy, fatigue, myalgia and headaches in some patients. Accidental infection... [5] Clinical signs and symptoms include acute onset of fever >101°F (38.3°C), head and body aches, malaise, and sometimes vomiting, then a characteristic... [6] Oct 23, 2024 — Serious rash caused by widespread infection of the skin (known as eczema vaccinatum). · Buildup of inflamed tissue around the vaccination site... [9] As detailed below under Clinical description, vaccinia disease can present in a variety of manifestations along a spectrum ranging from mild, localized disease...
Additional Symptoms
- Headaches
- Vaccinia disease
- eczema
- rash
- lymphadenopathy
- fever
- fatigue
Diagnostic Tests
Diagnostic Tests for Vaccinia Virus Infections
The diagnosis of vaccinia virus complications is usually straightforward and depends on obtaining the history of recent vaccinia virus exposure by vaccination or contact with a vaccinated individual [1]. Various diagnostic tests can aid in the detection of vaccinia, including:
- Electron Microscopy (EM): This test involves morphological characterization of the virus to confirm its presence [2].
- Viral Culture: This method involves growing the virus in a controlled environment to confirm its presence [12].
- Polymerase Chain Reaction (PCR): PCR is considered the most sensitive test for detecting vaccinia virus in clinical specimens [3, 7]. It can identify specific viral DNA sequences.
- Direct Fluorescent Antibody (DFA) Testing: DFA testing is a rapid but less sensitive test compared to PCR. It involves using fluorescent antibodies to detect the presence of the virus [4].
- Serological Tests: These tests involve analyzing blood samples for the presence of antibodies against vaccinia virus [14].
Diagnostic Techniques and Biosafety Considerations
Diagnostic laboratory procedures involving vaccinia virus can be performed in a biosafety level 2 laboratory with a class II biological safety cabinet [11]. Testing is also available through the Laboratory Response Network (LRN), which can be accessed through state and local health departments with confirmatory testing at CDC [12].
References:
[1] The diagnosis of vaccinia virus complications is usually straightforward and depends on obtaining the history of recent vaccinia virus exposure by vaccination or contact with a vaccinated individual.
[2] Electron microscopy involves morphological characterization of the virus to confirm its presence.
[3] PCR is considered the most sensitive test for detecting vaccinia virus in clinical specimens.
[4] DFA testing is a rapid but less sensitive test compared to PCR.
[7] The infection definitive diagnosis is made through morphological characterization of the virus by use of electron microscopy, followed by PCR for specific viral DNA sequences.
[11] Diagnostic laboratory procedures involving vaccinia virus can be performed in a biosafety level 2 laboratory with a class II biological safety cabinet.
[12] Testing is also available through the Laboratory Response Network (LRN), which can be accessed through state and local health departments with confirmatory testing at CDC.
Additional Diagnostic Tests
- Serological Tests
- Electron Microscopy
- Viral Culture
- Polymerase Chain Reaction
- Direct Fluorescent Antibody Testing
Treatment
Treatment Options for Vaccinia Infections
Vaccinia immune globulin intravenous (VIGIV) and tecovirimat are two drugs that have been approved for the treatment of complications resulting from smallpox vaccination, including vaccinia infections.
- Vaccinia Immune Globulin Intravenous (VIGIV): This is a prescription medicine that has been used to treat complications resulting from smallpox vaccination. It contains antibodies targeting the vaccinia virus and can help alleviate symptoms such as eczema vaccinatum, progressive vaccinia, severe generalized vaccinia, and vaccinia infection in individuals with certain skin conditions [2][4].
- Tecovirimat (Tpoxx): This is a novel antiviral drug that has been approved for the treatment of smallpox. It has also been used to treat severe adverse events to vaccinia virus vaccination, although there are limited efficacy data in humans [10].
Other drugs, such as cidofovir and brincidofovir, have also been investigated for their potential use in treating vaccinia infections. Cidofovir holds great promise for treating human smallpox, monkeypox, and other poxvirus infections [6]. Brincidofovir is also approved via the animal rule and is available as an EA-IND for mpox treatment, which may offer some protection against mpox [15].
Treatment Goals
The primary goal of drug treatment for vaccinia infections is to alleviate symptoms and prevent complications. VIGIV has been shown to be effective in treating eczema vaccinatum, progressive vaccinia, severe generalized vaccinia, and vaccinia infection in individuals with certain skin conditions [2][4]. Tecovirimat has also been used to treat severe adverse events to vaccinia virus vaccination, although more research is needed to fully understand its efficacy in humans [10].
Important Considerations
It's essential to note that the use of VIGIV and tecovirimat should be guided by a healthcare professional. These drugs may have side effects, and their use should be carefully considered on an individual basis.
References: [1] The first drug for the treatment of smallpox, tecovirimat, was approved in July 2018. [2] Vaccinia immune globulin (human) is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of complications resulting from smallpox vaccination. [4] VIGIV has been used to treat eczema vaccinatum, progressive vaccinia, severe generalized vaccinia, and vaccinia infection in individuals with certain skin conditions. [6] Cidofovir holds great promise for treating human smallpox, monkeypox, and other poxvirus infections. [10] Tecovirimat has been used to treat severe adverse events to vaccinia virus vaccination, although there are limited efficacy data in humans. [15] Brincidofovir is also approved via the animal rule and is available as an EA-IND for mpox treatment.
Differential Diagnosis
Differential Diagnosis of Vaccinia
Vaccinia, also known as cowpox or smallpox vaccine virus, can be challenging to diagnose due to its similarity in symptoms with other viral infections. The following conditions are considered in the differential diagnosis of vaccinia:
- Generalized varicella-zoster virus (VZV) infection: This condition presents with a similar rash and fever pattern as vaccinia.
- Generalized herpes simplex virus (HSV) infection: HSV can cause a severe skin rash, which may be mistaken for vaccinia.
- Erythema multiforme: A skin condition characterized by target-shaped lesions, which can be confused with vaccinia.
- Impetigo: A bacterial skin infection that can present with similar symptoms to vaccinia.
According to [1], the differential diagnosis of vaccinia also includes:
- Progressive vaccinia: A rare and severe form of vaccinia that can spread rapidly and is often fatal.
- Eczema vaccinatum: A condition where the vaccine virus spreads to other parts of the body, causing a widespread rash.
In addition, [2] notes that the differential diagnosis of smallpox (caused by variola virus) includes:
- Rocky Mountain spotted fever
- Syphilis
- Varicella-zoster virus
- Drug eruptions
- Insect bites
- Kawasaki disease
It's essential to consider these conditions in the differential diagnosis of vaccinia, as they can present with similar symptoms and require different treatments.
References:
[1] MacLeod DT, Nakatsuji T ... (search result 3) [2] Conditions to consider in the differential diagnosis of smallpox include the following: Rocky Mountain spotted fever. Syphilis. Varicella-zoster virus. Drug eruptions. Insect bites. Kawasaki disease. ... Treatment of Vaccinia and Cowpox Virus Infections in Mice with CMX001 and ST-246. Viruses. 2010 Dec. 2(12):2681-95. [QxMD MEDLINE Link]. (search result 15)
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