21.引起家禽霍亂的病原Pasteurella multocida，其gallacida亞種最主要可以在那種禽類分離到？
(A)雞
(B)水禽
(C)火雞
(D)鸚鵡

對禽病的領域沒有很了解

不過在禽病學第14版上有看到這段

Based upon DNA homology studies P. multocida was divided into 3 subspecies, namely P. multocida subspecies multocida, P. multocida subspecies septica, and P. multocida subspecies gallicida, that could be recognized by physiological properties (77). However, subsequent studies using multilocus enzyme electrophoresis (11), multilocus sequence typing (116), and multilocus sequence analysis (10) have all identified only 2 lineages within P. multocida. It appears that the subspecies gallicida is an artificial unit. Although biotyping by fermentation patterns has provided useful information (32), it appears that identification at the subspecies level is not reliable and cannot be recommended.

意思是PM subsp. gallicida實際上不存在嗎?

求高手講解