Summary Of Exposure |
A) TOXIC CLASS: Alphavirus belongs to the family Togaviridae. Diseases that are produced by alphaviruses usually follow typical epidemiological patterns reflecting mosquito (arthropod-borne) transmission. Alphaviruses are made up of 29 species that are nearly globally distributed and include 3 major areas: aquatic viruses, arthralgic viruses, and encephalitic viruses. This management is limited to a discussion of alphaviruses of human importance occurring as natural/emerging pathogens and include: Chikungunya virus, Mayaro virus, O'Nyong-Nyong virus, Sindbis virus (also known as Ockelbo (Sweden), Pogosta (Finland) or Karelian fever (Russia)), Eastern equine encephalitis virus, Western equine encephalitis virus, and the Venezuelan equine encephalitis virus (it is discussed in limited detail in this management - See the VENEZUELAN EQUINE ENCEPHALITIS management for detailed information).
B) TOXICOLOGY: These viruses are transmitted via mosquito (human-mosquito-human cycle (except aquatic viruses)) bites resulting in widespread and potentially serious epidemics. Arthralgic alphaviruses are typically found in the Old World with the exception of the Mayaro virus that has been found in South America. Chikungunya virus is the most important human pathogen of the arthralgic alphaviruses. Likewise, the most important human pathogens of encephalitic alphaviruses are Eastern equine encephalitis and Venezuelan equine encephalitis viruses.
C) TRANSMISSION: An alphavirus is transmitted to humans by the bite of an infected mosquito. CHIKUNGUNYA: Other modes of possible transmissions could be by a blood transfusion and blood-borne transmission (cases have occurred in laboratory and healthcare personnel). In utero transmission has been reported rarely during the second trimester, and rarely from mother (during the viremic stage) to the newborn at the time of birth. It has not been reported in infants through breastfeeding.
D) VECTOR: Various mosquito species transmit alphaviruses. CHIKUNGUNYA: Aedes aegypti and Aedes albopictus mosquitos (same vectors that transmit dengue virus). MAYARO: Haemagogus mosquitoes; Aedes aegypti mosquito species. O'NYONG-NYONG: Anopheles mosquitoes primarily Anopheles gambiae and Anopheles funestus. EASTERN EQUINE ENCEPHALITIS: Mosquito species can vary depending on the region. In North America, Culex (C peccator, C erraticus) and Uranotaenia sapphirinia mosquito species; Culex (Melanoconion) and C. (Mel.) pedroi are the principal vectors in South America. Others include Aedes canadensis, Coquillettidia perturbans and Culex mosquito species. SINDBIS: Culex and Culiseta mosquito species are suspected potential vectors. WESTERN EQUINE ENCEPHALITIS: Culex (Culex) tarsalis is the primary species.
E) EPIDEMIOLOGY: CHIKUNGUNYA: Outbreaks of Chikungunya fever have occurred. The disease is endemic in rural areas of Africa. Outbreaks have also occurred in China and India. Chikungunya can be underreported because the disease can appear similar to dengue, malaria, and other acute infectious diseases of the tropics. Infrequent cases have been reported in Italy and France. From 2006 to 2011, 117 cases of Chikungunya fever were reported among US travelers who had travelled to areas with known outbreaks. In July 2014, the first case of locally acquired chikungunya was reported in Florida. This represents the first time that mosquitoes have spread the illness to non-travelers in the United States. MAYARO: The Mayaro virus is an emerging virus that is similar to chikungunya. It has caused outbreaks of febrile illness in the Amazon region and on the Central Plateau of Brazil as well other South American countries. O'NYONG-NYONG: The first cases occurred in Uganda in the late 1950s and 1960s and affected 2 million people. Most recent major outbreaks have been reported in the Indian Ocean region, India and Southeast Asia. It has also caused 3 large outbreaks in Africa. This virus produces symptoms similar to chikungunya and is usually a self-limiting illness that lasts a few days. SINDBIS: In Finland, the Sindbis virus has caused cyclical epidemics in 7 year cycles resulting in hundreds to even thousand of cases; the pattern leading up to epidemics remains unknown. EASTERN EQUINE ENCEPHALITIS: This virus primarily causes equine and domestica disease. Human cases are uncommon. In the US, 220 confirmed humans cases of Eastern equine encephalitis occurred from 1964 to 2004. An average of 6 cases are reported in the US each year. WESTERN EQUINE ENCEPHALITIS: Human cases are uncommon. As of 1988, fewer than 10 cases per year have been reported in the US due in part to mosquito control and changes in irrigation methods. VENEZUELAN EQUINE ENCEPHALITIS: Overt encephalitis is more likely to occur in children with case fatality rates up to 35% compared to 10% in adults that develop encephalitis due to Venezuelan equine encephalitis virus infection.
F) WITH POISONING/EXPOSURE
1) MILD TO MODERATE TOXICITY: ARTHRALGIC ALPHAVIRUSES: These diseases (ie, Chikungunya, Mayaro, O'Nyong-Nyong, and Sindbis) are usually self-limiting. Acute symptoms can last up 2 weeks. Fatalities are uncommon, but some patients can develop significant morbidity secondary to ongoing severe arthralgia. Symptoms usually include the abrupt onset of fever followed by malaise, headache, rash, arthralgia, joint swelling, and muscle pain.
2) SEVERE TOXICITY: ENCEPHALITIC ALPHAVIRUSES: Eastern equine encephalitis is rarely observed in humans, but it is the most virulent of all the encephalitic alphaviruses. It has a case-fatality rate of 50% to 70%. The virus can present as two types of illness (systemic and encephalitic). Systemic infection appears similar to other alphaviruses (ie, fever, chills, malaise, arthralgia and myalgia). The encephalitic form occurs abruptly in children while older children and adults develop symptoms a few days after systemic illness. Symptoms usually include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, cyanosis, seizures, and coma. Death has also been reported. Venezuelan equine encephalitis usually produces flu-like symptoms. Encephalitis is rare but neurologic sequelae are common. The Western equine encephalitis virus usually produces no symptoms or a nonspecific febrile illness or aseptic meningitis. Of those cases that develop more severe symptoms, encephalitis or encephalomyelitis can result in confusion, tonic-clonic seizures, somnolence, coma and death. Case fatality rate in humans is estimated at 3% to 7%. Severe neurologic sequelae (especially young children less than one year old) can develop in 15% to 30% of cases that survive encephalitis. OTHER: Chikungunya is usually a self-limiting illness that resolves in 7 to 10 days and is rarely fatal. During several outbreaks, meningo-encephalitis, Guillain-Barre syndrome, mild hemorrhage, myocarditis, and hepatitis and death (rarely) have occurred in some cases. The mechanism for these events remains unknown.
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Vital Signs |
3.3.1) SUMMARY
A) WITH THERAPEUTIC USE 1) Fever is an early symptom of alphavirus infections.
3.3.3) TEMPERATURE
A) WITH POISONING/EXPOSURE 1) Fever is a prominent early symptom of alphavirus infections (Figueiredo & Figueiredo, 2014; Seymour et al, 2013; Zacks & Paessler, 2010; Rampal et al, 2007). a) CHIKUNGUNYA: Fever is likely to occur in most patients (up to 92% of cases) (Figueiredo & Figueiredo, 2014). 1) In one study of chikungunya infection (n=20), fever occurred abruptly in all cases and was often associated with chills and joint pain. Fever lasted up to 7 days in most patients (Rampal et al, 2007).
b) EASTERN EQUINE ENCEPHALITIS: Rarely reported in humans. Fever develops suddenly after an incubation period of 4 to 10 days along with muscle pain and headache that become increasingly more severe (Zacks & Paessler, 2010). c) MAYARO: This virus can produce outbreaks of febrile illness, but symptoms usually resolve within 3 to 5 days (Figueiredo & Figueiredo, 2014). d) O'NYONG-NYONG: Fever is characteristic of O'Nyong-Nyong virus and shares many of the same symptoms (ie, fever, rash, severe arthralgia) as Chikungunya infections (Seymour et al, 2013). |
Heent |
3.4.1) SUMMARY
A) WITH POISONING/EXPOSURE 1) Ocular changes including iridocyclitis, neuroretinitis and uveitis can occur with chikungunya infection.
3.4.3) EYES
A) WITH POISONING/EXPOSURE 1) CHIKUNGUNYA: Ocular changes including iridocyclitis, neuroretinitis and uveitis can occur with infection (Figueiredo & Figueiredo, 2014; Caglioti et al, 2013). These changes typically resolve and do not produce any permanent vision changes (Caglioti et al, 2013).
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Cardiovascular |
3.5.2) CLINICAL EFFECTS
A) HYPOTENSIVE EPISODE 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In one study of chikungunya infection (n=20), hypotension (blood pressure between 90/70 to 100/70 mm Hg) was observed in 8 patients at the time of admission (Rampal et al, 2007).
B) MYOCARDITIS 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: Chikungunya is usually a self-limiting illness that resolves in 7 to 10 days and is rarely fatal. During several outbreaks, meningo-encephalitis, Guillain-Barre syndrome, mild hemorrhage, myocarditis, and hepatitis and rarely death have occurred in some cases. The mechanism for these events remains unknown (Caglioti et al, 2013).
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Neurologic |
3.7.2) CLINICAL EFFECTS
A) HEADACHE 1) WITH POISONING/EXPOSURE a) SUMMARY: Headache can develop with alphavirus infections (Figueiredo & Figueiredo, 2014).
b) CHIKUNGUNYA: Headache is frequently reported with illness (62% of cases) (Figueiredo & Figueiredo, 2014).
c) EASTERN EQUINE ENCEPHALITIS: Rarely reported in humans. Headache occurs after an incubation period of 4 to 10 days and becomes increasingly more severe (Zacks & Paessler, 2010).
d) MAYARO: Headache is likely to occur with illness; however symptoms usually resolve within 3 to 5 days (Figueiredo & Figueiredo, 2014).
B) SEIZURE 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In some cases, severe neurologic manifestations can include febrile seizure, encephalitis and meningitis which usually follow the early stages of illness (ie, fever, myalgia, rash) (Morrison, 2014; Figueiredo & Figueiredo, 2014). These events are more likely to occur in neonates, patients older than 65 years and those with pre-existing medical conditions (Morrison, 2014). 1) In one study of chikungunya infection (n=20), seizures (focal or generalized) developed in 6 cases (Rampal et al, 2007).
b) EASTERN EQUINE ENCEPHALITIS: Although this virus is rarely reported in humans, it is considered the most virulent of all the encephalitic alphaviruses (Zacks & Paessler, 2010). The virus can present as two types of illness (systemic and encephalitic). Systemic infection appears similar to other alphaviruses (ie, fever, chills, malaise, arthralgia and myalgia). The encephalitic form occurs abruptly in infants while older children and adults develop symptoms a few day after systemic illness. Symptoms usually include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, cyanosis, seizures, and coma. Death has also been reported (Centers for Disease Control and Prevention (CDC), 2010). c) WESTERN EQUINE ENCEPHALITIS: This viral infection usually results in no symptoms or a nonspecific febrile illness or aseptic meningitis. Of those cases that develop more severe symptoms, encephalitis or encephalomyelitis can result in confusion, tonic-clonic seizures, somnolence, coma and death. Case fatality rate in humans is estimated at 3% to 7%. Severe neurologic sequelae (especially young children less than one year old) can develop in 15% to 30% of cases that survive encephalitis (Zacks & Paessler, 2010). C) ENCEPHALITIS 1) WITH POISONING/EXPOSURE a) EASTERN EQUINE ENCEPHALITIS: This virus is rarely observed in humans, but it is the most virulent of all the encephalitic alphaviruses (Centers for Disease Control and Prevention (CDC), 2010; Zacks & Paessler, 2010). It has a case-fatality rate of 50% to 70% (Zacks & Paessler, 2010). The virus can present as two types of illness (systemic and encephalitic). Systemic infection appears similar to other alphaviruses (ie, fever, chills, malaise, arthralgia and myalgia). The encephalitic form occurs abruptly in children while older children and adults develop symptoms a few day after systemic illness. Symptoms usually include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, cyanosis, seizures, and coma. Death has also been reported (Centers for Disease Control and Prevention (CDC), 2010). 1) DIAGNOSTIC FINDINGS: MRI imaging and CT scans of the head have found alterations in the basal ganglia and thalami areas suggesting brain edema, ischemia and hypoperfusion in the early stage of disease (Zacks & Paessler, 2010).
b) CHIKUNGUNYA: Although not common, severe neurologic manifestations can include encephalitis, meningitis and febrile seizures which usually follow the early stages of illness (ie, fever, myalgia, rash) (Morrison, 2014; Figueiredo & Figueiredo, 2014). These events are more likely to occur in neonates, patients older than 65 years and those with pre-existing medical conditions (Morrison, 2014) 1) Chikungunya is usually a self-limiting illness that resolves in 7 to 10 days and is rarely fatal. During several outbreaks, meningo-encephalitis, Guillain-Barre syndrome, mild hemorrhage, myocarditis, and hepatitis and rarely death have occurred in some cases. The mechanism for these events remains unknown (Caglioti et al, 2013)
c) WESTERN EQUINE ENCEPHALITIS: This viral infection usually results in no symptoms or a nonspecific febrile illness or aseptic meningitis. Of those cases that develop more severe symptoms, encephalitis or encephalomyelitis can result in confusion, tonic-clonic seizures, somnolence, coma and death. Case fatality rate in humans is estimated at 3% to 7%. Severe neurologic sequelae (especially young children less than one year old) can develop in 15% to 30% of cases that survive encephalitis (Zacks & Paessler, 2010). D) MENINGITIS 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: Although not common, severe neurologic manifestations can include encephalitis, meningitis and febrile seizures which usually follow the early stages of illness (ie, fever, myalgia, rash) (Morrison, 2014; Figueiredo & Figueiredo, 2014). These events are more likely to occur in neonates, patients older than 65 years and those with pre-existing medical conditions (Morrison, 2014).
E) DISTURBANCE OF CONSCIOUSNESS 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In one study of chikungunya infection (n=20), alterations in consciousness including confusion, disorientation, drowsiness and delirium occurred in most cases (Rampal et al, 2007).
F) COMA 1) WITH POISONING/EXPOSURE a) EASTERN EQUINE ENCEPHALITIS: Although this virus is rarely reported in humans, it is considered the most virulent of all the encephalitic alphaviruses (Zacks & Paessler, 2010). The virus can present as two types of illness (systemic and encephalitic). Systemic infection appears similar to other alphaviruses (ie, fever, chills, malaise, arthralgia and myalgia). The encephalitic form occurs abruptly in children while older children and adults develop symptoms a few day after systemic illness. Symptoms usually include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, cyanosis, seizures, and coma. Death has also been reported (Centers for Disease Control and Prevention (CDC), 2010).
b) WESTERN EQUINE ENCEPHALITIS: This viral infection usually results in no symptoms or a nonspecific febrile illness or aseptic meningitis. Of those cases that develop more severe symptoms, encephalitis or encephalomyelitis can result in confusion, tonic-clonic seizures, somnolence, coma and death. Case fatality rate in humans is estimated at 3% to 7%. Severe neurologic sequelae (especially young children less than one year old) can develop in 15% to 30% of cases that survive encephalitis (Zacks & Paessler, 2010).
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Gastrointestinal |
3.8.2) CLINICAL EFFECTS
A) VOMITING 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In one study of chikungunya infection (n=20), vomiting occurred in almost all patients during the initial phase of illness (Rampal et al, 2007).
b) EASTERN EQUINE ENCEPHALITIS: The encephalitic form can occur abruptly in infants while older children and adults develop symptoms a few days after systemic illness. Symptoms usually include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, cyanosis, seizures, and coma. Death has also been reported (Centers for Disease Control and Prevention (CDC), 2010).
B) NAUSEA 1) WITH POISONING/EXPOSURE a) SINDBIS: In Finland, a study of 337 patients with Sindbis virus infection, nausea was reported in 18% (49/269) of patients (Sane et al, 2011).
C) STOMATITIS 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In one study of chikungunya infection (n=20), stomatitis and oral ulcerations occurred in almost all patients during the initial phase of illness (Rampal et al, 2007).
D) DIARRHEA 1) WITH POISONING/EXPOSURE a) EASTERN EQUINE ENCEPHALITIS: The encephalitic form can occur abruptly in children while older children and adults develop symptoms a few days after systemic illness. Symptoms usually include fever, headache, irritability, restlessness, drowsiness, vomiting, diarrhea, cyanosis, seizures, and coma. Death has also been reported (Centers for Disease Control and Prevention (CDC), 2010).
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Hepatic |
3.9.2) CLINICAL EFFECTS
A) INFLAMMATORY DISEASE OF LIVER 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: Chikungunya is usually a self-limiting illness that resolves in 7 to 10 days and is rarely fatal. During several outbreaks, meningo-encephalitis, Guillain-Barre syndrome, mild hemorrhage, myocarditis, and hepatitis and rarely death have occurred in some cases. The mechanism for these events remains unknown (Caglioti et al, 2013).
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Dermatologic |
3.14.2) CLINICAL EFFECTS
A) ITCHING OF SKIN 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In one study of chikungunya infection (n=20), pruritus occurred in 14 patients. Bilateral lymphedema was also a common finding following exposure (Rampal et al, 2007).
B) MACULOPAPULAR ERUPTION 1) WITH POISONING/EXPOSURE a) Maculopapular eruptions/rash is a common finding with alphavirus infections (Figueiredo & Figueiredo, 2014; Rampal et al, 2007; Sane et al, 2011; Seymour et al, 2013). b) CHIKUNGUNYA: A non-pruritic maculopapular rash can develop on the face, limbs, and trunk about 2 to 5 days after the onset of illness and can last for up to 10 days (Figueiredo & Figueiredo, 2014). 1) In one study of chikungunya infection (n=20), macules or maculopapular rash developed in 5 patients (Rampal et al, 2007).
c) MAYARO: Rash is characteristic finding of Mayaro virus (Figueiredo & Figueiredo, 2014). d) O'NYONG-NYONG: Rash is characteristic of O'Nyong-Nyong virus. However, the illness is usually self-limiting and resolves in a few days (Seymour et al, 2013). e) SINDBIS: In Finland, a study of 337 patients with Sindbis virus infection, papular rash was reported in 96% (321/334) of patients (Sane et al, 2011). |
Musculoskeletal |
3.15.2) CLINICAL EFFECTS
A) MUSCLE PAIN 1) WITH POISONING/EXPOSURE a) SUMMARY: Muscle pain is commonly reported with alphavirus infections (Figueiredo & Figueiredo, 2014; Seymour et al, 2013; Sane et al, 2011; Zacks & Paessler, 2010).
b) EASTERN EQUINE ENCEPHALITIS: Rarely reported in humans. General muscle pain develops after an incubation period of 4 to 10 days (Zacks & Paessler, 2010).
c) O'NYONG-NYONG: Muscle pain is characteristic of O'Nyong-Nyong virus. However, the illness is usually self-limiting and resolves in a few days (Seymour et al, 2013).
d) SINDBIS: In Finland, a study of 337 patients with Sindbis virus infection, muscle pain was reported in 62% (182/292) of patients (Sane et al, 2011).
B) JOINT PAIN 1) WITH POISONING/EXPOSURE a) Joint symptoms are characteristic of alphavirus infections (Figueiredo & Figueiredo, 2014; Seymour et al, 2013; Sane et al, 2011; Rampal et al, 2007). b) CHIKUNGUNYA: Joint pain is a common symptom (up to 87% of cases) as well as back pain (67% of cases). Symptoms are usually more intense in the morning and are likely to affect the ankles, wrists and joints of the hand. However, larger joints (ie, knee, shoulder, spine) can also be affected (Figueiredo & Figueiredo, 2014). 1) In one study of chikungunya infection (n=20), joint pain occurred in all cases and was described as moderate to severe. The joints commonly involved included the knee, ankle, wrist, small joints of the hands, elbow and feet. Characteristic stooped flexed posture also developed in 10 patients (Rampal et al, 2007).
c) MAYARO: Arthralgia in large joints has been observed with this virus (Figueiredo & Figueiredo, 2014). d) SINDBIS: In Finland, a study of 337 patients with Sindbis virus infection, joint symptoms were reported in 96% (322/335) of patients (Sane et al, 2011). e) O'NYONG-NYONG: Arthralgia is a common finding with an O'Nyong-Nyong illness, and it can be severe in some patients (Seymour et al, 2013). C) JOINT SWELLING 1) WITH POISONING/EXPOSURE a) CHIKUNGUNYA: In one study of chikungunya infection (n=20), joint swelling occurred in 17 patients most commonly reported in the knees and ankles (Rampal et al, 2007).
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