PLASMODIUM, HAEMOPROTEUS AND LEUCOCYTOZOON 



279 



Pi'e valence : This species is common 

 in northern and southeastern United States, 

 along the Gulf Coast and Pacific Coast and 

 in Canada in mountainous or hilly areas 

 wherever cold, rapid streams permit suit- 

 able blackfly vectors to breed. It was 

 first seen by Smith (1895) in eastern United 

 States, and has been encountered in North 

 Dakota, Minnesota, Nebraska, Wisconsin, 

 Illinois, Virginia, South Carolina, Georgia, 

 Alabama, Florida, Pennsylvania, Missouri, 

 Texas, California, Ontario and Manitoba 

 (Volkmar, 1929; Skidmore, 1932; Johnson, 

 1942, 1945; Johnson et al. . 1938; Hinshaw 

 and McNeil, 1943; Banks, 1943; Stoddard, 

 Humlin and Cooperrider, 1952; Travis, 

 Goodwin and Gambrell, 1939; Mosby and 

 Handley, 1943; Wehr and Coburn, 1943; 

 Kozicky, 1948; West and Starr, 1940; 

 Atchley, 1951; Bierer, 1950; Simpson 

 Anthony and Young, 1956; Savage and Isa, 

 1945; Fallis, Pearson and Bennett, 1954). 



Travis, Goodwin and Gambrell (1939) 

 found it in 81% of 357 adult domesticated 

 turkeys in Georgia, Florida, Alabama 

 and South Carolina. Mosby and Handley 

 (1943) found it in 40% of 268 captivity- 

 reared wild turkeys, wild turkeys and 

 domestic turkeys in Virginia. Kozicky 

 (1948) found it in 21% of 92 captivity-reared 

 and all of 5 native wild turkeys in Penn- 

 sylvania. Atchley (1951) found it in all of 

 10 domestic turkeys in South Carolina. 



Morphology : The mature macroga- 

 metes and microgametocytes are rounded 

 at first but later become elongate, aver- 

 aging 20 to 22 |j. in length. Their host 

 cells are elongate, averaging 45 by 14|j,, 

 with pale cytoplasmic "horns" extending 

 out beyond the enclosed parasite. The 

 host cell is elongate, forming a long, thin, 

 dark band along one side of the parasite; 

 often it is split to form a band on each 

 side of the parasite. The cytoplasm of the 

 macrogametes is rather dark blue and the 

 nucleus compact and red when stained 

 with a Romanowsky stain. The cytoplasm 

 of the microgametocytes is very pale blue 

 and the nucleus diffuse and pale pink. 



Life Cycle : The life cycle of L. 

 smithi is similar to that of L. simondi, 

 but is not known in nearly so much detail. 



The prepatent period is about 9 days. 

 Newberne (1955) and Richey and Ware 

 (1955) described hepatic schizonts in the 

 liver parenchyma of infected turkeys. 

 According to Newberne, they measure 10 

 to 20 by 7 to 14 /J., with a mean of 13. 5 by 

 10. 5ji . The earliest stage he saw con- 

 tained round and crescent-shaped, baso- 

 philic cytomeres. These developed into 

 masses of deeply staining merozoites which 

 completely filled the host cell cytoplasm. 

 Megaloschizonts have not been seen. 



The vectors of L. siiiitlii are various 

 species of blackflies {Siiiinlii(m). Skid- 

 more (1932) found that S. occidentale 

 transmitted it in Nebraska, Johnson et al. 

 (1938) found S. nigroparvuui to be the 

 vector in Virginia, and Richey and Ware 

 (1955) showed that S. slossonae could 

 transmit it in South Carolina. The stages 

 in the blackflies are similar to those of 

 L. simondi. 



Pathogenesis : L. smithi is markedly 

 pathogenic for turkeys, and extremely 

 heavy losses have been reported. Savage 

 and Isa (1945) described an outbreak in 

 Manitoba in which more than 3000 out of 

 8000 birds died in 2 months. Not more 

 than 10%) of the birds which became ill re- 

 covered. Stoddard, Humlin and Cooper- 

 rider (1952) described an outbreak in 

 Georgia in which 75% of 1600 5-month-old 

 turkeys died within a week. Adult birds 

 are less seriously affected than poults, 

 and the disease runs a slower course in 

 them, but even they may die. 



Affected poults fail to eat, appear 

 droopy and tend to sit. They move with 

 difficulty when disturbed; in the later 

 stages there may be incoordination, and 

 the birds may suddenly fall over, gasp, 

 become comatose and die. If the birds do 

 not die within 2 or 3 days after signs of 

 disease appear, they recover. 



Recovered birds continue to carry 

 parasites in their blood. Some may show 

 no serious after-effects, but others de- 

 velop a chronic type of the disease. They 

 never regain their vigor, and the males 

 pay little attention to the females and 

 rarely strut. They often have moist 



