Encephalitis in Midwest IX. Neutralizing Antibodies in Wild Birds of Midwestern States

Abstract

WEE) viruses. These collections were a part of an extensive search for natural reservoirs of these organisms In the virus diseases termed the arthropod-borne encephalitides, considerable work points definitely toward birds as biological reservoirs of these viruses, including St. Louis encephalitis, Japanese B encephalitis, and Eastern and Western equine encephalomyelitis. The literature describes the possible part birds may play as reservoirs and their possible role in the infection of man with one of these viruses(1-7). The present paper deals with wild birds and results of blood serum surveys in Colorado, Kansas, and Missouri in 1949, in which several species of birds have been sampled and tested for past infections of the St. Louis (St. L.) and Western equine encephalomyelitis

Methods. Surveys were made in Kansas and Missouri in 1949 from late spring through the fall. Samples were collected in Colorado during the third week of November 1949. Species sampled'and results of tests are given in Table I and Table II. The majority of the waterfowl blood samples was obtained through cooperation of the U. S. Fish and Wildlife Service personnel during banding operations at Swan Lake and Squaw Creek National Wildlife Refuges in Missouri. These blood samples were taken from the wing veins. Other bloods were taken from birds collected during special surveys in southeastern and western Kansas and in Weld County, Colorado. During the Colorado survey, turkey and chicken sera were also collected for testing. The turkeys sampled were mature-sized birds reared from poults that year and were bled at a Greeley, Colo., processing plant just prior to slaughter. The chickens were full grown and of various ages. Blood was sampled just prior to slaughter at a Greeley processing plant. Both the chickens and turkeys were from flocks in Weld County and surrounding counties. The sera were tested for neutralizing antibodies against St. L. and WEE viruses according to a modification of the methods given in the U. S. Army Laboratory Manual(8).