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West Nile virus cases in humans reported in multiple U.S. states

Written by Dr. Daliah Wachs
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A 6th case of West Nile virus has been confirmed in Clark County, Nevada. The Southern Nevada Health District has declared an “outbreak of mosquito-borne diseases” following new cases of the virus being reported.

This summer has been a wetter season in the Southwest, most likely causing an uptick in mosquito activity.

States throughout the country have been reporting cases of West Nile virus as well, with the highest occurring in Arizona (42 cases as of 7/23/19 per CDC).

 

wnv-activity-07092019.jpg

 

West Nile Virus Disease Cases* and Presumptive Viremic Blood Donors by State – United States, 2019 (as of July 23, 2019)

State

Neuroinvasive

Disease Cases†

Non–neuroinvasive

Disease Cases

Total

cases

Deaths

Presumptive viremic

blood donors‡

Arizona

42

15

57

1

16

Arkansas

1

0

1

1

0

California

2

0

2

1

1

Colorado

0

1

1

0

0

Iowa

0

2

2

0

0

Kentucky

1

0

1

0

0

Maryland

0

1

1

0

0

Missouri

1

0

1

0

0

Nebraska

1

0

1

1

0

Nevada

1

0

1

0

0

New Jersey

1

0

1

0

0

North Dakota

1

0

1

0

0

Oklahoma

1

2

3

0

0

South Dakota

0

1

1

0

0

Virginia

0

1

1

0

0

Wyoming

1

0

1

0

0

Totals

53

23

76

4

17

*INCLUDES CONFIRMED AND PROBABLE CASES.
†INCLUDES CASES REPORTED AS MENINGITIS, ENCEPHALITIS, OR ACUTE FLACCID PARALYSIS.
‡PRESUMPTIVE VIREMIC BLOOD DONORS (PVDS) ARE PEOPLE WHO HAD NO SYMPTOMS AT THE TIME OF DONATING BLOOD THROUGH A BLOOD COLLECTION AGENCY, BUT WHOSE BLOOD TESTED POSITIVE WHEN SCREENED FOR THE PRESENCE OF WEST NILE VIRUS. SOME PVDS DEVELOP SYMPTOMS AFTER DONATION.
PLEASE REFER TO STATE HEALTH DEPARTMENT WEB SITES FOR FURTHER DETAILS REGARDING STATE CASE TOTALS.

What is West Nile virus?

West Nile virus was originally discovered in the 1930’s in the West Nile district of Uganda.  It is believed to have reached the United States in the late 1990’s.

It’s in the family of Flaviviridae in which the disease is vector transmitted, such as by ticks, or mosquitoes, and can infect mammals as hosts. West Nile is in the same family as Zika, Yellow Fever, Dengue Fever, and Japanese Encephalitis.

Culex genus/species of mosquitoes are the usual culprit.  They feed from evening to morning, hence are more active during those times.

How is West Nile transmitted?

A mosquito contracts the disease while feeding on an infected bird and then can transmit it to humans.

 

WNV-transmission-cycle.jpg

 

What are the symptoms of West Nile virus infections?

80% of those infected do not exhibit symptoms.  Some however, may elicit the following if they have mild illness:

  • Fever
  • Body aches
  • Fatigue
  • Nausea
  • Vomiting
  • Joint  pains
  • Weakness
  • Rash

Rarely (1 in 150 people) may become seriously ill with neuroinvasive symptoms.  These include:

  • Headache
  • Neck pain/Stiff neck
  • High fever
  • Sensitivity to light (photophobia)
  • Tremors
  • Weakness
  • Paralysis
  • Confusion
  • Disorientation
  • Seizures
  • Coma
  • Death

Since mosquitoes are the primary vector, avoiding them is paramount to limiting infection.  We recommend the following:

Clean up areas of standing water around the house such as kiddie pools, puddles, buckets as they provide a breeding ground for mosquitoes.

Wear light long sleeve clothing, pants tucked into socks/shoes when outside.

Use DEET or insect repellant that can also be sprayed onto clothes when planning to be outdoors.

Be aware that many mosquitoes are active from dusk till dawn.

If bitten by a mosquito, contact your local medical provider if you have any of the aforementioned symptoms.

 

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Daliah Wachs is a guest contributor to GCN news, her views and opinions, medical or otherwise, are her own. Doctor Wachs is an MD,  FAAFP and a Board Certified Family Physician.  The Dr. Daliah Show , is nationally syndicated M-F from 11:00 am - 2:00 pm and Saturday from Noon-1:00 pm (all central times) at GCN.