west nile virus
          encephalitides
arboviruses

west nile virus
WNV was first identified in the US in 1999 in New York City.  The virus  established itself within the avian population making birds its primary host.  It was then subject to the birds migratory paths allowing it to spread to the different states across the nation.  Since 1999, the virus has spread south and west along the US.  At the end of 2003, only Oregon and Washington remain unaffected, but that is predicted to change by the summer of 2004.  WNV amplifies within birds and then is transferred to other animals by mosquitoes.  This natural cycle sometimes takes a detour by infecting animals that are unable to amplify the virus.  These are referred to as dead-end host; such as humans and  horses.  The dead-end host will feel the effects of the virus but a mosquito will be unable to transfer the virus from it to another host.  So infection of humans is undesirable for the virus as it ensures certain doom.  Other confirmed dead-end hosts include human, horse, dog, squirrel, cat, rabbit, black bear, aquarium seal, alligator, bovine, sheep, goat, llama, alpaca, emu, deer, chipmunk, bat, skunk and others.  Most of these animals rarely show symptoms or their species is mildly effected by the virus.  Early detection is key in monitoring the virus and its impact on public health and the environment.
In order to monitor for WNV here in Cabarrus County, several surveillance factors have been established.  1)the State lab will receive birds for testing as long as they meet the set requirements  2)mosquito sampling/collection for identification and testing  3)monitoring of State Veterinary reports for unusual activity  4)monitoring of State Communicable Disease reports for arboviral activity.  Δ
References & more info:   NIAID  CDC

arboviruses
The word arbovirus comes from the condensed term: arthropod-borne virus.  Arthropod being an animal with a segmented body, jointed appendages and an exoskeleton such as mosquitoes, ticks and spiders.  These viruses are found all over the world.  In the US the main arboviruses regarding mosquitoes, other than WNV, are LAC, WEE, SLE, EEE (see below for more detail).  The majority of infections are asymptomatic or result in flu-like symptoms.  Only a small percentage of infected people develop encephalitis.  Encephalitis is a swelling of the brain which can lead to temporary or long term damage or even death.
For the most part, humans and domestic animals are dead-end hosts that end the transmission cycle of the virus; there is not enough viral concentration in the blood of the host to continue the cycle.
To minimize exposure to these diseases, adequate personal protection and good public health are essential.  Δ
References & more info:   CDC

encephalitides-

lacrosse encephalitis/(LAC)
LAC is mostly found in the Midwestern states with approximately 75 cases reported in the continental US every year.  It is under reported due to the misdiagnosis of many cases.  There is no treatment for LAC, only management of its symptoms.  LAC has a host reservoir of chipmunks and tree squirrels.  Δ
References & more info:  CDC

western equine encephalitis/(wee)
WEE is also an alpha virus.  It is a leading cause of encephalitis in horses and humans in north America.  If affects mainly the western states including western Canada.  The virus infects most songbirds via the  mosquito species that breed in stream and irrigation drainage waters.  The virus can also infect other mammals as well.  Most cases are asymptomatic or just mild sickness.  Clinical cases include fever, headache, nausea, vomiting, anorexia and malaise.  Δ
References & more info:   CDC

st.louis encephalitis/(sle)
SLE is the most common mosquito-transmitted disease to humans in America.  It is a flavivirus that causes about 200 fatalities a year.  Humans are exposed to SLE though inclusion in the mosquito-bird transmission cycle.  As with many encephalitides, SLE is under-diagnosed.  Δ
References & more info:   CDC

malaria
Malaria kills around 1 million people every year worldwide.  Malaria is caused by the parasite Plasmodium which is transferred to people  by mosquitoes.  The parasite enters the salivary glands of the mosquito where it is then injected into the next host.
This disease is a major problem in the countries of Africa, Central & South America, Asia and the Indonesian Islands.  Symptoms include fever, shivering, headache, joint pain and vomiting.  Severe cases progress to convulsions, coma and even death. 

Local transmission of malaria occurred in northern Virginia in August of 2002.  There were 2 cases, one a 19 year old and the other a 15 year old.  There both were diagnosed and confirmed with malaria.  Both people have fully recovered after the malaria was identified and treated for.  Both patients had not been exposed through international travel, blood transfusion, organ transplant or needle sharing.  They did live 1/2 mile from each other and less then 10 miles from Washington Dulles International Airport.  Mosquito testing identified Anopheles quadrimaculatus and Anopheles punctipennis as positive with the same strain of P.vivax as the patients  Finding a positive pool of mosquitoes in the midst of active cases is very unusual.  Anopheles mosquitoes must be infected with the P.vivax parasite between 1-2 weeks before being able to infect other people.  Yet only have a life span of about 4 weeks.  This only allows a small window to trap  positive mosquitoes.

In 2003, Palm Beach County Florida recorded 7 cases of locally acquired malaria.  All were the same strain of P.vivax and are thought to originate from the same single source.  All patients were men with a mean age of 35 and all engaged in outdoor activities and live within 10 miles of the Palm Beach International Airport.  Mosquitoes trapped in that area were all negative for the parasite. 

 Δ
References & more info:   WHO   CDC

reports
CDC
PHPM
NPIC
USGS