Volume 12, Number 8—August 2006
West Nile Virus Epizootiology, Central Red River Valley, North Dakota and Minnesota, 2002–2005
|Year||Primary transmission season†||Thermal accumulations (degree-days)‡||Vector abundance§||Human cases in ND¶||Seasonal MIR#||Passerine seroprevalence|
|2002, introductory||92 days (11 Jun–10 Sep)||1,067||230||17||0.0 (n = 5,871)||No birds tested|
|2003, epidemic||92 days (11 Jun–10 Sep)||1,022||21||617||5.7 (n = 5,432)||17% (n = 82)|
|2004, cold||51 days (7 Jul–1 Sep)||371||9||20||0.0 (n = 1,245)||58% (n = 52)|
|2005, equilibrium?||84 days (20 Jun–11 Sep)||867||29||86||1.3 (n = 3,123)||57% (n = 143)|
*ND, North Dakota; MIR, minimum infection rate.
†Time between first and last appearances of host-seeking Culex tarsalis mosquitoes in Mosquito Magnet traps.
‡Based on developmental threshold temperature of 14.3°C for WNV growth in Cx. tarsalis (14).
§Average number of Cx. tarsalis mosquitoes captured per trap-night in Grand Forks, ND.
¶Data from North Dakota Department of Public Health (15).
#No. of WNV-infected Cx. tarsalis mosquitoes per 1,000.
- Page created: December 09, 2011
- Page last updated: December 09, 2011
- Page last reviewed: December 09, 2011
- Centers for Disease Control and Prevention,
National Center for Emerging and Zoonotic Infectious Diseases (NCEZID)
Office of the Director (OD)