According to the USDA Animal and Plant Health Inspection Service (APHIS), three of the outbreaks were confirmed on 17 April and one on 20 April.

The largest outbreak so far reported was one in a flock of 5.3 million commercial chickens in Osceola county, Iowa, confirmed on 20 April.

Laying hens are affected in this outbreak, according to Des Moines Register.

The disease was also confirmed on two commercial turkey farms in Kandiyohi county, Minnesota – one with 9,000 birds and the other with 23,000.

A backyard flock of 33 mixed poultry in Juneau county, Wisconsin, was also affected late last week.

All these outbreaks were in area affected by the Mississippi flyway for migrating birds.

Overview

• The latest cases bring the total number of high-path avian flu outbreaks since December 2014 to 54.
• Outbreaks have occurred in poultry in 13 states.
• Three of the early outbreaks were caused by the H5N8 sub-type of the virus but in all those since mid-February 2015, the H5N2 variant has been confirmed.
• The majority of outbreaks have been in commercial turkeys (40); three have been in commercial chickens and 11 in backyard flocks.
• The number of poultry affected by these outbreaks has reached a total of just over eight million. This figure includes over 5.6 million commercial chickens, almost 2.4 million commercial turkeys and over 7,000 backyard poultry.
• The disease has also affected five captive wild birds.