Geology topics
Publications and source records attributed to Milton Friend.
What is avian botulism? Avian botulism, or Western duck sickness, is one of the three most important disease problems of wild migratory birds. Each year, many birds are paralyzed or die after exposure to a toxin produced by the botulinum bacterium. Two of the seven toxin types that have been identifies cause mortality in wild birds; one of these types, type C, is most often associated with dieoffs of ducks, while type E primarily affects gulls and loons.
No abstract available.
No abstract available.
The effects of selected environmental pollutants on avian salt gland function were studied in the mallard duck, Anas pZatyrhynchos . DDE and several organophosphates were found to have an inhibitory effect on the ability of these glands to concentrate and secrete salt from the body. DDE significantly reduced secretion rates from the salt glands. More severe effects were observed following exposure to organophosphate insecticides; reduction in gland size, reduced ability of the birds to secrete Na+ via the salt glands, and reductions in cholinesterase activities in the salt gland and hypothalamus all contributed to elevated mortality levels in treatment birds over controls.
We start off with light heart, but as we near the marsh, we stop abruptly in shock and horror. The shoreline, where only last evening we saw thousands of sleek, apparently healthy birds, is now littered with their bodies. Most of them are ducks, but here and there we see a Canada goose, a gull, an avocet, a black-necked stilt, a pelican..... This is the way Jensen and Williams (1964) described an outbreak of avian botulism in a western marsh. It illustrates, more vividly than dry facts and body counts, the impact a disease can have on a population of waterfowl. When we think about waterfowl diseases, we probably think first of botulism and then of lead poisoning, the result of birds swallowing spent lead shot. In fact, these are the only two diseases discussed by Kortright (1942) and Day (1949) in major books on North American waterfowl, attesting to both their importance and our years of experience with them. Botulism was probably an old problem in 1910, but the catastrophic loss that summer of millions of aquatic birds near the Great Salt Lake and in California marked the beginning of real concern about its impact on waterfowl populations (Jensen and Williams, 1964). Concern about lead poisoning of waterfowl began a few years later following the investigations of Wetmore (1919). Today, more than 50 years after these early reports, botulism and lead poisoning are still major disease problems of North American waterfowl, but they are no longer the only ones. After years of study, we have learned much about how these two diseases occur and about their prevention and control. But now there are new pathogens and new toxic compounds that can afflict waterfowl populations. So rather than redescribe the established disease problems of the past and present, I will concentrate on some of these new waterfowl disease problems of the present and future.
There has been considerable speculation regarding possible imteractlons within biological systems between synthetic environmental pollutants and infectious disease agents (1-11). This type of interaction has been studied in our laboratory using the mallard, Anas platyrhynchos , as a test species (5,6). Since adult ducks are refractory to the overt manifestations of duck virus hepatitis (DVH) (12) and because duck hepatitis virus (DHV) has a predilection for the liver, the organ responsible for the metabolism of many chemicals, (13) an experiment was undertaken to determine if infection with DHV had any effect on the toxicity to adult mallards of p,p'-DDT or technical grade dieldrin.
Injections of duck hepatitis virus (DVH) decreased, and exposure to DDT increased, hepatic microsomal mixed-function oxidase activity. Injection of DFV prior to exposure to DDT did not prevent stimulation of hepatic microsomal mixed-function oxidase activity by DDT and may have enhanced it.