Tuesday, August 28, 2012

A Trip down the Nile

West Nile that is… a Flavivirus; West Nile Virus (WNV) is a vector born disease spread by mosquitoes. Birds are the amplifying hosts, transmitting the disease to mosquitoes when bitten. The disease is spread when a mosquito then bites a person. “West Nile virus may also be spread through blood transfusions and organ transplants. 

It is possible for an infected mother to spread the virus to her child through breast milk” (USNLM, 2012). The American robin (Turdus migratorius) and the American crow (Corvus brachyrhynchos) are the most common carriers of WNV in the Western Hemisphere.

The infected mosquito species vary according to geographical area; in the US, Culex pipiens (Eastern US), Culex tarsalis (Midwest and West), and Culex quinquefasciatus (Southeast) are the main sources (Hayes, et al., 2005).

“Thus far in 2012 (as of 8/24/12), 47 states have reported West Nile virus infections in people, birds, or mosquitoes. A total of 1118 cases of West Nile virus disease in people, including 41 deaths, have been reported to CDC. Of these, 629 (56%) were classified as neuroinvasive disease (such as meningitis or encephalitis) and 489 (44%) were classified as non-neuroinvasive disease” (CDC, 2012).

“The 1118 cases reported thus far in 2012 is the highest number of West Nile virus disease cases reported to CDC through the third week in August since West Nile virus was first detected in the United States in 1999. Approximately 75 percent of the cases have been reported from 5 states (Texas, Mississippi, Louisiana, South Dakota, and Oklahoma) and almost half of all cases have been reported from Texas)” (CDC, 2012).

Generally, people infected with WNV have positive prognosis; however severe cases can lead to
Encephalitis or meningitis; and can lead to brain damage and death.  10% of patients with severe cases do not survive (USNLM, 2012).

Side note and disease alert 2:

There is a possible outbreak of another disease…

“A second person has died of a rare, rodent-borne disease after visiting Yosemite National Park earlier this summer and park officials are warning past visitors to be aware of some flu-like aches and symptoms as fears of a possible outbreak mount” (AP, 2012).

This outbreak is a hantavirus . Taken from the U.S. National library of medicine; "Hantavirus is a life-threatening disease spread to humans by rodents that has symptoms similar to influenza. Hantavirus is carried by rodents, especially deer mice. The virus is found in their urine and feces, but it does not make the animal sick.

It is believed that humans can get sick with this virus if they come in contact with contaminated dust from mice nests or droppings. You may come in contact with such dust when cleaning homes, sheds, or other enclosed areas that have been empty for a long time".

Hantavirus does not spread between humans.


Center for Disease Control (CDC)

Hayes EB, Komar N, Nasci RS, Montgomery SP, O'Leary DR, Campbell GL (2005). "Epidemiology and transmission dynamics of West Nile virus disease". Emerging Infect. Dis. 11 (8): 1167–73

Associated press (AP):

U.S. National Library of medicine  http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0004457/

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