During a discussion about travel-related diseases, several residents were discussing various viruses and the need to counsel about mosquito prevention. One resident noted, “Did you know that Chikungunya was recently found on the mainland US. I think last summer.” Another resident asked, “What is the most common arbovirus that we see in kids? I don’t really don’t know. I’m also not sure I really know the clinical findings. ” No one was sure of the answer including the attending physician, so they decided to look it up.
Arboviruses are viruses transmitted by arthropods (primarily mosquitos and ticks) to humans. Most infections are asymptomatic. Many others have mild symptoms such as an influenza-like illnesses. But for some patients they can cause neuroinvasive disease with meningitis, encephalitis and flaccid paralysis. Some patients also unfortunately die.
Diagnosis is by serum or cerebrospinal fluid IgM antibody to the specific virus. Treatment is supportive only as there is no specific treatment and currently there are no vaccines for prevention. Mosquito bite and tick bite prevention are the best options for families and can be reviewed here.
A systematic review of West Nile Virus (WNV) neuroinvasive disease in adults showed those infected can have a lengthy recovery with many sequelae, particularly muscle weakness, fatigue, myalgia and headache commonly along with memory loss, depression and concentrating difficulty.
Common arbovirus characteristics include:
- West Nile Virus
- Transmitted by Culex mosquito with birds as reservoir
- Seen in areas of Africa (originally identified in 1937 in Uganda in the West Nile District), Europe, the Middle East, North America and West Asia
- Has spread to most states in the United States and many Canadian provinces and is the most common reported arbovirus in children
- Older children and teenagers seem to be more common
- Incubation period usually 2-6 days, but 2-14 days is possible
- 70-80% asymptomatic, 20% influenza like illness (i.e. headache, nausea, emesis, fatigue), <1% have severe symptoms
- LaCrosse Virus
- Transmitted by Aedes triseriatus that breed in tree waterholes. Chipmunks and grey squirrels are amplifiers
- Incubation period usually 5-15 days
- Most commonly seen in Midwest, MidAtlantic and southeastern U.S.
- Most asymptomatic, some with influenza like illness, few have severe symptoms but children (especially younger) are more likely to have them than adults especially
- Eastern Equine Encephalitis Virus
- Transmitted by Culiseta melanura with birds as reservoir
- Most commonly seen in US, Atlantic and Gulf states but also Great Lakes region
- Incubation period usually 4-10 days
- May be asymptomatic, can have abrupt onset of neuroinvasive disease. Has a high rate of death
- Powassan Virus
- Transmitted by Ixodes ticks with small woodland mammals as reservoir – only one of the major viruses to be transmitted by a tick
- Most commonly seen in US Northeastern and Great Lakes region
- Incubation period is 1 week to 1 month
- May be asymptomatic but can have mild or severe symptoms
St. Louis Encephalitis
- Transmitted by mosquitos with birds as reservoir
- Seen across the US but more often in Mississippi Valley and Gulf Coast
- Incubation period is 5-15 days
- May be asymptomatic but can have mild or severe symptoms
- Western Equine Virus
- Transmission by mosquito with birds as reservoir
- Mainly see in western US
- Incubation 5-10 days
- Maybe asymptomatic but can have mild or severe symptoms
- Transmitted by mosquitos particularly Aedes aegypti and Aedes albopictus with humans as reservoir during epidemic periods
- In the world it is seen in Africa, Asia, Europe, and the Indian and Pacific Oceans. In the US, most domestic cases are from Puerto Rico and the US Virgin Islands, but first case on mainland was in July 2014.
- According to the CDC “As of September 22, 2015, a total of 467 chikungunya virus disease cases have been reported to ArboNET from 39 U.S. states for 2015.”
- Incubation usually 5-7 days but the range is 1-12 days
- Most people are asymptomatic, may have more fever and polyarthralgia or severe symptoms
Some other mosquito – borne diseases include Dengue Fever, Japanese Encephalitis Virus, Malaria, Rift Valley Fever, Yellow Fever. Some other tick-borne diseases include Babesiosis, Colorado Tick, Ehrlichiosis, Lyme disease, Q Fever, Rocky Mountain Spotted Fever, and Tularemia.
Cases of arbovirus are underreported because may people are asymptomatic or have mild disease. For cases of arbovirus induced neuroinvasive disease in the United States for all age group the most common is West Nile Virus (WNV) with LaCrosse virus (LCV) second. But for the <18 year old age group, ArboNET data from 2003-2012 shows that LaCrosse virus is most common with West Nile Virus being second, and Eastern Equine Encephalitis Virus (EEEV) third. Other reported viruses included Powassan, St. Louis Encephalitis and unspecified California serogroup virus. These 6 viruses along with Western Equine Encephalitis Virus and Chikungunya Virus are reportable viruses as of 2015. There was a total of 1200 cases of neuroinvasive disease from 2003-2012 resulting in 22 deaths in the pediatric age range. WNV and LCV reported 1% death rates (N=3 and 9 respectively) in the pediatric population, but EEEV had only 30 cases but 10 of them unfortunately died (33%).
Questions for Further Discussion
1. What other vector-borne diseases can you name?
2. What are the similarities and differences of Chikungunya and Dengue?
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
To view current news articles on this topic check Google News.
To view images related to this topic check Google Images.
To view videos related to this topic check YouTube Videos.
Centers for Disease Control. General Questions About West Nile Virus. Available from the Internet at http://www.cdc.gov/westnile/faq/genquestions.html (rev. 3/15/15, cited 9/22/15)
Centers for Disease Control. La Crosse Encephalitis Frequently Asked Questions. Available from the Internet at http://www.cdc.gov/lac/ (rev. 9/16/2009, cited 9/22/15)
Centers for Disease Control. Eastern Equine Encephalitis. Available from the Internet at http://www.cdc.gov/EasternEquineEncephalitis/index.html (rev. 6/23/2011, cited 9/22/15)
Centers for Disease Control. Powassan Virus. Available from the Internet at http://www.cdc.gov/powassan/index.html (rev. 2/9/15, cited 9/22/15)
Centers for Disease Control. Saint Louis Encephalitis. Available from the Internet at http://www.cdc.gov/sle/ (rev. 1/29/2010, cited 9/25/15)
Centers for Disease Control. Chikungunya Virus. Available from the Internet at http://www.cdc.gov/Chikungunya/index.html (rev. 8/3/15, cited 9/25/15)
Gaensbauer JT, Lindsey NP, Messacar K, Staples JE, Fischer M. Neuroinvasive arboviral disease in the United States: 2003 to 2012. Pediatrics. 2014 Sep;134(3):e642-50.
Patel H, Sander B, Nelder MP. Long-term sequelae of West Nile virus-related illness: a systematic review. Lancet Infect Dis. 2015 Aug;15(8):951-9.
Lindsey NP1, Lehman JA, Staples JE, Fischer M. West Nile Virus and Other Nationally Notifiable Arboviral Diseases – United States, 2014. MMWR Morb Mortal Wkly Rep. 2015 Sep 4;64(34):929-34. doi: 10.15585/mmwr.mm6434a1.
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa Children’s Hospital