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2012 Nationally Notifiable Diseases and Conditions
and Current Case Definitions
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Powassan Virus Neuroinvasive Disease Cases Reported by State, 2001-2012
Clip:
Data table: N=47
From 2001 through 2012, POWV neuroinvasive disease cases have been reported in Maine (2), Michigan (1), Minnesota (19), New York (13), Pennsylvania (1), Virginia (1), and Wisconsin (10).
2013 N=2
New Hampshire 1
New York 1
Powassan Virus Maps - Human - USA
Statistics & Maps | Powassan Virus Disease | CDC
Powassan Virus Background
Clip:
Powassan
Powassan (POW) virus is a North American tickborne flavivirus. POW virus was named for the town of Powassan, Ontario, where the first recognized case of disease caused by the virus occurred in 1958. From 1958 -- 2001, 31 human POW encephalitis cases were reported from Canada and the northeastern United States. POW encephalitis is associated with significant long-term morbidity and has a case-fatality rate of 10%-15%.
In North America, POW virus has been isolated from four tick species, including Ixodes cookei, Ix. marxi, Ix. spinipalpus, and Dermacentor andersoni. A variant POW virus also has been isolated from Ix. Scapularis. Evidence of infection has been found in 38 mammal species. Unlike Ix. scapularis, the primary vector for Lyme disease, Ix. cookei rarely search for hosts on vegetation and are often found in or near the nests or burrows of medium-sized mammals, such as woodchucks. Infections have occurred from May to December, with a peak during June--September when ticks are most active. As with many infectious agents transmitted by Ixodid ticks, few infected persons recalled tick bites because these ticks are small.
Because of the lack of awareness and the need for specialized laboratory tests to confirm diagnosis, the frequency of POW encephalitis may be greater than previously suspected. POW encephalitis should be included in the differential diagnosis of all encephalitis cases occurring in the northern United States, especially the northeast. Laboratory tests for POW virus infection are not commercially available but can be requested through state public health laboratories for testing at CDC. Awareness should be promoted among clinicians and public health staff, and tick-bite prevention strategies emphasized for the general public.
Because there is no vaccine or specific therapy for POW encephalitis, the best means of prevention is protection from tick bite. This includes using insect repellents, avoiding walking through tall grass and vegetation, wearing light-colored clothing with long sleeves and pants tucked into socks or boots, clearing brushy areas, and removing ticks before they attach or as soon after attachment as possible. Checking family pets also can prevent ticks from entering the home. Because Ix. cookei are often found on woodchucks and skunks and may be the primary vector of POW virus, environmental controls reducing human contact with small and medium-sized mammals should reduce risk for exposure to POW virus-infected ticks. Persons should keep areas adjacent to their home clear of brush, weeds, trash, and other elements that could support small and medium-sized mammals. When removing rodent nests, avoid direct contact with nesting materials and use sealed plastic bags for disposal and to prevent direct contact with ticks.
Powassan Virus - Historical Maps
Source:
Home | Powassan Virus Disease | CDC
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Clip:
INTRODUCTION
Powassan virus (POWV) is an arthropod-borne virus (arbovirus) in the family of Flaviviridae, genus
Flavivirus. Human POWV infections are rare and associated with acute onset of fever, profound muscle weakness, confusion, headache, nausea, vomiting, and stiff neck. Severe signs and symptoms include respiratory
distress, tremors, seizures, paralysis, and coma.1-3 Most individuals with POWV infections develop meningoencephalitis and many have long-term neurologic sequelae; 10%-15% of cases are fatal.3-5 POWV is transmitted to humans through the bite of an infected tick. Symptoms usually begin at least 1 week (range 8-34 days) following infection.2 Apart from supportive and symptomatic management, there are no specific treatments for or vaccines available to prevent POWV infection.
Initially isolated in 1958 from the brain of a boy aged 5 years who developed encephalitis and died, POWV
was named after the northern Ontario town where the child resided.5 The first POWV infection reported in
the United States occurred in New Jersey in 1970. Since then, POWV infections have been reported rarely and
have occurred in Maine, Michigan, Minnesota, New York, Vermont, and Wisconsin.6-7
Tickborne Powassan Virus Infections Among Wisconsin Resident
and Current Case Definitions
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Powassan Virus Neuroinvasive Disease Cases Reported by State, 2001-2012
Clip:
Data table: N=47
From 2001 through 2012, POWV neuroinvasive disease cases have been reported in Maine (2), Michigan (1), Minnesota (19), New York (13), Pennsylvania (1), Virginia (1), and Wisconsin (10).
2013 N=2
New Hampshire 1
New York 1
Powassan Virus Maps - Human - USA
Statistics & Maps | Powassan Virus Disease | CDC
Powassan Virus Background
Clip:
Powassan
Powassan (POW) virus is a North American tickborne flavivirus. POW virus was named for the town of Powassan, Ontario, where the first recognized case of disease caused by the virus occurred in 1958. From 1958 -- 2001, 31 human POW encephalitis cases were reported from Canada and the northeastern United States. POW encephalitis is associated with significant long-term morbidity and has a case-fatality rate of 10%-15%.
In North America, POW virus has been isolated from four tick species, including Ixodes cookei, Ix. marxi, Ix. spinipalpus, and Dermacentor andersoni. A variant POW virus also has been isolated from Ix. Scapularis. Evidence of infection has been found in 38 mammal species. Unlike Ix. scapularis, the primary vector for Lyme disease, Ix. cookei rarely search for hosts on vegetation and are often found in or near the nests or burrows of medium-sized mammals, such as woodchucks. Infections have occurred from May to December, with a peak during June--September when ticks are most active. As with many infectious agents transmitted by Ixodid ticks, few infected persons recalled tick bites because these ticks are small.
Because of the lack of awareness and the need for specialized laboratory tests to confirm diagnosis, the frequency of POW encephalitis may be greater than previously suspected. POW encephalitis should be included in the differential diagnosis of all encephalitis cases occurring in the northern United States, especially the northeast. Laboratory tests for POW virus infection are not commercially available but can be requested through state public health laboratories for testing at CDC. Awareness should be promoted among clinicians and public health staff, and tick-bite prevention strategies emphasized for the general public.
Because there is no vaccine or specific therapy for POW encephalitis, the best means of prevention is protection from tick bite. This includes using insect repellents, avoiding walking through tall grass and vegetation, wearing light-colored clothing with long sleeves and pants tucked into socks or boots, clearing brushy areas, and removing ticks before they attach or as soon after attachment as possible. Checking family pets also can prevent ticks from entering the home. Because Ix. cookei are often found on woodchucks and skunks and may be the primary vector of POW virus, environmental controls reducing human contact with small and medium-sized mammals should reduce risk for exposure to POW virus-infected ticks. Persons should keep areas adjacent to their home clear of brush, weeds, trash, and other elements that could support small and medium-sized mammals. When removing rodent nests, avoid direct contact with nesting materials and use sealed plastic bags for disposal and to prevent direct contact with ticks.
Powassan Virus - Historical Maps
Source:
Home | Powassan Virus Disease | CDC
----
--------
Clip:
INTRODUCTION
Powassan virus (POWV) is an arthropod-borne virus (arbovirus) in the family of Flaviviridae, genus
Flavivirus. Human POWV infections are rare and associated with acute onset of fever, profound muscle weakness, confusion, headache, nausea, vomiting, and stiff neck. Severe signs and symptoms include respiratory
distress, tremors, seizures, paralysis, and coma.1-3 Most individuals with POWV infections develop meningoencephalitis and many have long-term neurologic sequelae; 10%-15% of cases are fatal.3-5 POWV is transmitted to humans through the bite of an infected tick. Symptoms usually begin at least 1 week (range 8-34 days) following infection.2 Apart from supportive and symptomatic management, there are no specific treatments for or vaccines available to prevent POWV infection.
Initially isolated in 1958 from the brain of a boy aged 5 years who developed encephalitis and died, POWV
was named after the northern Ontario town where the child resided.5 The first POWV infection reported in
the United States occurred in New Jersey in 1970. Since then, POWV infections have been reported rarely and
have occurred in Maine, Michigan, Minnesota, New York, Vermont, and Wisconsin.6-7
Tickborne Powassan Virus Infections Among Wisconsin Resident
