Birds

Aves (birds) is the class of vertebrates, numbering about 8600 species. In the USSR there are about 700 species of birds - representatives of 26 units, including more than half of species are included in the group of sparrows.
Flight - main mode of transportation birds - has left a definite imprint on the structure of birds and led to the similarity of the overall organization of numerous representatives of this class. Body Ii. has faired. Smooth surface closely to the body plumage reduces resistance in the air. Easy Perova cover is however a good heat insulator; separate groups of feathers (flight feathers on the wings and tail, forming a tail) provide the possibility of flight. Special developed muscles, resulting in motion wings, which resulted in a significant increase in the sternum and education high ridge sternum (Kiel). The skeleton of birds lightweight yet durable. Ease due vozduhonosnye many hollow bones, fortress - a fusion of separate parts of the skeleton. Teeth P. absent, the function they perform the bill and stomach. Breathing is enhanced by a special air bags, connected with light.
Birds typical of the far seasonal migration and along with this characteristic has strict attachment to the places of nesting in certain habitats, where P. reproduce by laying eggs, covered with solid lime shell.
Birds play a significant role in human life as suppliers of valuable products - down duvets, feather, meat, eggs.
The medical value of birds diverse. Birds found more than 50 diseases, pathogenic for humans. P. are sources of pathogens mosquito encephalitis (see) and encephalomyelitis (see), psittacosis (see), some worms. For agents of diseases such as encephalitis, salmonellosis (see), toxoplasmosis (see), listeriosis (see), birds play the role of additional hosts, who along with mammals support the existence in nature foci related diseases (see Natural focality). Causative agents of some diseases P. move mechanically. P. may also play a role in the dispersion of infected fleas.
A significant portion dangerous to human diseases known in birds, is a vector-borne. Circulation of pathogens in the centers is carried out mostly by mosquitoes (see), less ticks (see). In this regard, the most important birds living near water or collecting food and nesting on the ground in the forest litter. Foci retransmission diseases most often associated with P. breeding large and dense colonies. Due to the considerable mobility of birds can pass the infection beyond the hearth, and, most importantly, to bring its natural foci in settlements where it can easily spread in poultry and birds-of Sinanthropus, in particular pigeons (for example, psittacosis) or gulls in the vicinity of fisheries (for example, contamination lentetsom).
Human infection from birds is transmissible by (often through mosquitoes), aspirazione (through contaminated dust in the breeding areas), in the care of P., handling their carcasses (ornithosis)through nutritional - when eating meat, eggs, water contaminated by feces of birds (Salmonella infections, toxoplasmosis), through the skin is in direct contact with infected P. (fungal infections).
During seasonal migrations of birds carry agents of different diseases in the far distance. So, with the help of birds encephalitis, Murray valley of Northern tropical regions in Australia enters the southern subtropical part; gulls and guillemots carry pathogens Salmonella from wintering places in Jutland to breeding grounds in Sweden. Transfer P. pathogenic agents of long-distance pays great attention to the world health organization.