Cryptosporidiosis is a common parasitic infection in birds that is caused by more than 25 Cryptosporidium species and genotypes. Many of the genotypes that cause avian cryptosporidiosis are poorly characterized. The genetic and biological characteristics of avian genotype III are described here and these data support the establishment of a new species, Cryptosporidium proventriculi. Faecal samples from the orders Passeriformes and Psittaciformes were screened for the presence of Cryptosporidium by microscopy and sequencing, and infections were detected in 10 of 98 Passeriformes and in 27 of 402 Psittaciformes. Cryptosporidium baileyi was detected in both orders. Cryptosporidium galli and avian genotype I were found in Passeriformes, and C. avium and C. proventriculi were found in Psittaciformes. Cryptosporidium proventriculi was infectious for cockatiels under experimental conditions, with a prepatent period of six days post-infection (DPI), but not for budgerigars, chickens or SCID mice. Experimentally infected cockatiels shed oocysts more than 30 DPI, with an infection intensity ranging from 4,000 to 60,000 oocysts per gram (OPG). Naturally infected cockatiels shed oocysts with an infection intensity ranging from 2,000 to 30,000 OPG. Cryptosporidium proventriculi infects the proventriculus and ventriculus, and oocysts measure 7.4 × 5.8 μm. None of the birds infected C. proventriculi developed clinical signs.

隐孢子虫病是鸟类中常见的寄生虫感染，是由超过25种隐孢子虫种类和基因型引起的。许多导致禽类隐孢子虫病的基因型特征不清。禽类基因型III的遗传和生物学特性在这里进行了描述，这些数据支持了一个新物种隐孢子虫的建立。通过显微镜检查和测序，从Passeriformes和Psittaciformes的粪便样本中筛选出隐孢子虫的存在，并在98个Passeriformes中的10个和402 Psittaciformes中的27个中检测到感染。在两个订单中均检测到了百色隐孢子虫。隐孢子虫在雀形目中发现了I型和禽类I型基因，在翼形兽中发现了C. avium和C.provertriculi。在实验条件下，原头隐孢子虫对小鹦鹉具有传染性，感染期为感染后六天（DPI），但对虎皮鹦鹉，鸡或SCID小鼠则没有。经实验感染的小鹦鹉排出的卵囊超过30 DPI，感染强度范围为每克4,000至60,000卵囊（OPG）。自然感染的小鹦鹉会排出卵囊，感染强度在2,000至30,000 OPG之间。隐孢子虫前庭感染前庭和心室，卵囊大小为7.4×5.8μm。没有一只鸟感染了C.proventriculi 发展出临床体征。