2012 may be worst year yet for West Nile

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According to the CDC Americans are facing what may be the largest outbreak of West Nile virus since the disease was first detected in the U.S. in 1999.

What is West Nile disease?

1.       West Nile virus, a member of the Japanese encephalitis virus antigenic complex.

2.       It can lead to a wide range of clinical symptoms from asymptomatic disease to severe meningitis and encephalitis.

3.       It causes neuroinvasive disease, particularly in the elderly or the immunosuppressed host.

4.      The usual presentation is a self-limited illness, called West Nile fever.

5.     The illness is indistinguishable from dengue fever and other viral grippes (acute febrile highly contagious viral disease).

6.     The illness is characterized by fever, headache, malaise, back pain, myalgias and anorexia persisting for 3 to 6 days.

7.     Despite the name “West Nile fever”, some patients report very low grade or no fever at all.

8.     Eye pain, pharyngitis, nausea, vomiting, diarrhea, and abdominal pain can also occur.

9.    A maculopapular rash appears in approximately one-half of patients.

10.   It can present as encephalitis, meningitis, or an acute asymmetric flaccid paralysis.

11.   Encephalitis with muscle weakness and flaccid paralysis is particularly suggestive of WN virus infection.

12.   One can also have tremor, myoclonus, and parkinsonian features such as rigidity, postural instability, and bradykinesia.

13.    The disease occurs in mosquito season.

14.   Diagnosis can be confirmed by demonstrating either specific IgM antibody or viral nucleic acid in serum obtained within the first 8 days of illness.

15.   Convalescent-phase serum should be tested for IgM antibody if acute serum IgM antibody or NAAT tests are negative.

16.   Total leukocyte counts in peripheral blood are mostly normal or elevated.

17.   CSF should be tested for IgM antibody as well as serologic testing.

18.   CSF usually demonstrates a pleocytosis often with a predominance of lymphocytes as well as an elevated protein concentration.

19.   Birds are the primary hosts of the West Nile (WN) virus; the virus can be spread when a mosquito bites an infected bird and then bites a human or animal.

20.   The virus is not transmitted through person-to-person contact.

21.   Most cases develop after being bitten by an infected mosquito.

22.   Most people who contract WN virus do not develop any symptoms.

23.   About 25% of people develop mild illness, called West Nile fever, which usually resolves spontaneously.

24.   One in 230 infected people develop severe or neuroinvasive disease, which affects the central nervous system and can result in permanent neurologic dysfunction or even death.

25.   There is no treatment for WN virus.

26.   The best way to avoid becoming infected is by preventing mosquito bites with repellents containing DEET, picaridin, oil of lemon eucalyptus, or IR3535 and by wearing protective clothing while outdoors.

27.   Pregnant or nursing women, people over age 50, and people who have received organ transplants or have other conditions that weaken the immune system are especially encouraged to take preventive measures.

28.    There have been a limited number of cases of people who acquired WN virus after receiving donated blood or organs.

29.   In the USA all blood donations are screened for WN virus to identify infected blood.

30.   In India, this test is not done.