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Localization of Endogenous Developmental Stages of Cryptosporidium-- Meleagridis Slavin, 1955 (Apicomplexa, Cryptosporidiidae) in Birds

PAVLASEK I
Veterinarni Medicina 39, 1994, 733-742

Localization of endogenous developmental stages of C. meleagridis was studied on the basis of observation of 4734 preparations from individual parts (in the distance of approx. 5 cm) of the small intestine, caeca (collum caeci, corpus, apex caeci), colon, cloaca, bursa of Fabricius, respiratory organs (sinus infraorbitalis, larynx, trachea, bronchi, air sacs) using the method of scraping mucous epithelium stained according to Giemsa after fixation with methanol (as well as histologically) from 155 naturally infected 9-66 day turkeys (Meleagris gallopavo f. dom.) in four large flocks in Central Bohemia, ten 46 and 47 day chicks (Gallus gallus f. dom.) and 1-3 day chicks infected experimentally. The protozoon was detected in various stages of its development in the microvilli of the small intestine of chicks 23-39 days old in the portion of 40-80 cm from the end of the duodenum. On bay 5 after infection, asexual stages were found in experimentally infected chickens as near as in 8-12 cm. All forms of endogenous developmental stages including oocysts occurred usually massively in approx. 10 cm from the site of bifurcation of the caeca (plica ileocaecalis) in the ileum and in the collum caeci. The infection was prominently less intensive in the case of mucous epithelium of the colon, in the cloaca only meronts occurred very sporadically showing various developmental stages. The findings in the bursa of Fabricius and in the organs of respiratory tract were negative. In a total of 129 turkeys examined post mortem on three farms C. meleagridis were observed, endogenous developmental stages of the protozoon were found in 55 (42.6%) cases. Asexual stages (meronts in different stages of development) were observed sporadically for the first time in 23 days old birds. Maximum of infected turkeys in which all developmental stages of C. meleagridis were localized above all in the ileum and collum caeci were 30-39 days old (out of the total number of 60 dead birds examined the infection occurred in 30, i.e. in 63.3%). C. meleagridis was found in nine out of 10 dead 46- and 47-day chicks on two farms and in five out of 98 dead 14-49 daychicks, in four out of 10 pullets 7-9 months old and in one out of 22 dead parrots (Cacatua molucensis) sent for routine examination to the State Veterinary Institute in Prague from different parts of Central Bohemia. Oocysts of C. meleagridis isolated from digesta of the ileum, of caeca and colon of naturally infected turkeys, chicks, pullets and the parrot were capable of spread of infection, and peroral infection with the dose of 1.10(5) oocysts/chick resulted in the normal course of intestinal form of cryptosporidial infection. The prepatent period lasted 60-96 hours, the patent period 7-10 days depending on the inoculum applied. The results of these transmission studies suggest low host specificity of C. meleagridis and draw attention to the possibility of mutual change of this protozoon among various avian species within the environment. The paper also discusses a relationship between the increased death rate in 27-40 day turkeys and enormous mortality of 46- and 47-day broiler chicks and the occurrence of C. meleagridis in the birds of this age category resulting in considerable economic losses in the given flocks. Thus, for these reasons as well as for practical significance in poultry keeping, further studies of all problems in this field are necessary and highly topical


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