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Notes on Avian Coccidiosis • 500 BOVGHTON,Notes on Arian Coccidiosi• [Oct.Auk NOTES ON AVIAN COCCIDIOSIS • BY DONALD C. BOUGHTON Plate 31 INTRODUCTION To suggestto the ornithologistthat his birds are hoststo a variety of interestinganimal formswhich have elaboratedmarvelously adapted modes of life within the arian body, is perhaps,to pressthe point too far. The hint, however, that some of these animals, as parasites,are the causesof severediseases in birds shouldarouse his concern. The Coccidiacomprise one groupof theseparasites. Coccidiaare one-celledanimals which grow and multiply in the epithelialcells of varioushigher animals,often in the liningof the intestine,causing destruction of host tissues. An end-product of the multiplicationcycle within the hostis the microscopicspore (oocyst) which passesfrom the host body in the fecal discharge. In most casesthe coccidianspore requires a developmentalperiod (sporulation)in a moist place outsidethe host, in order to producewithin itself the minute forms (sporozoites)which are capableof beginningagain the parasitic multi- plicationwithin a new host. Shoulda susceptiblebird ingesta few 'ripe' sporesof an appropriatearian coccidian,the latter would becomeestab- lished in the bird; the bird would then become'infected.' The resulting disease is called coccidiosis. Sincecoccidiosis is a seriousand widespreaddisease of birds,it may prove of interestto ornithologiststo presentbriefly a few factsregarding: (1) the two typesof avian Coccidia;(2) coccidiosisin smallbirds; (3) examination and sourcesof bird hosts;and (4) the distributionof Coccidiaamong bird groups. Two TYPES oF AVIAN COCCIDIA The Coccidiaof birds are divided into two genera,Isospora and Eimeria, whichare as distinguishableto the protozoologistas are Turdusand Zono- trichia to the ornithologist. Morphologicaldifferences are most apparent in the mature spores. When first dischargedfrom the bird, the spores containrounded masses of protoplasmand thoseof Isosporaand Eimeria look very much alike (P1.31, figs.1, 3). However, in the courseof several hours or a few days, dependingupon the coccidianspecies involved, the cysticcontent undergoes characteristic changes. To facilitate this develop- ment, fecal material containingspores may be culturedin 2 per cent potas- sium-bichromatesolution. The spore(oocyst) of Isosporaforms two sec- ondary cysts (sporocysts)shown in Figure2 (Plate31). Eachsecondary • From the Department of Animal and Plant Pathology, Rockefeller Institute for Medical Research, Princeton, New Jersey. Vol.1937 J BovGv•'rol,•,Noteson Arian Coccidiosis 501 cyst actuallycontains four minute,infective forms (sporozoites), but these are not readily madeout in detail. The sporeof Eimeria formsfour secon- dary cystsas shownin Figure4. Each of thesecontains only two infeetive forms (not readily made out in detail). For detaileddrawings of various eoeeidianspores the readeris referredto Becker(1934). The microphoto- graphspresented here faithfully reproducethe appearanceof the sporesas seenunder the microscope. Variousspecies of Eimerlaare responsiblefor the eoeeidiosisin quail, pigeons,and chickens. For a reviewof eoeeidiosisin thesebirds the reader is referredto Becker(1934) and for a detailedstudy of poultryeoeeidiosis to Tyzzer (1929)and Tyzzer et al. (1932). No authenticease of eoeeidiosis in poultry due to Isosporahas beenreported. Likewise,with a possible exceptionto be noted later, Eimeria is not found in perchingbirds. In 1910, Hadley condemnedthe House Sparrowand other small birds as eartiersof the poultry disease. Actuallythere is no evidenceto support this accusation,as has beenshown by severalworkers (Smith and Smillie; Johnson;Boughton, 1929). To a limited extent, sparrowsmay carry Eimerianspores mechanically, but they certainlyare not naturalreservoirs for poultry eoeeidiosis. Coeeidiaof the genusIsospora are found in many birds, especiallypas- setines. A recent survey (Boughton,1938) has shown that 173 spedes and subspeciesof birds have been reported as hostsof Isospora. One hundredand forty-sevenof thesebelong to the order Passeriformes,while the remainingtwenty-six are scatteredthrough eight other orders. When a sufficient number of individuals is examined, the incidenceof infection is found to be relatively high in most of thesebird species. For the English Sparrowit is practically100 per cent(Boughton, 1937). In the summerof 1933 the writer obtained the following records for Isospora from birds banded at the Baldwin Bird ResearchLaboratory: Catbird (Dumetella carolinensis),8 out of 11; Eastern House Wren (Troglodytesaedon aedon), 26 out of 45; EasternSong Sparrow (Melospiza melodia melodia), 82 out of 91; EasternField Sparrow(Spizella pusilla Fusilla), 10 out of 11; Eastern ChippingSparrow (Spizella passerlna passerina), 13 out of 16. The inci- denceis high alsoin troupialsand othercagebirds. CaptiveBirds of Para- dise are commonlyinfected with an Isosporawhich has recently been de- scribedas a newspecies (Boughton, 1937). COCCIDIOSIS IN SMALL BIRDS Typical coccidiosisin small birds causedby coccidiabelonging to the genusIsospora has been reported by variousEuropean workers (Condorelli and Fiore,Labb•, Laveran,Sj6bring, Wasielewski). The diseaseis similar in many respectsto eoeeidiosisin poultry. An infeetlonmay eventually 502 BOUGHTON,Noteson Arian Coccidiosis [Oct.['Auk lead to destructionof the intestinal epitheliumwith subsequentloss of appetite, emaciation,droopiness, diarrhea, and finally death due to acute enteriris. Sjrbfing reports finding adult birds in nature heavily infected. When approached,such birds could make only feebleattempts to fly away, and when capturedand caged,remained quiet, squattingon the abdomen, and wouldneither eat nor drink. Death usuallyfollowed shortly. Nestlings were found with severeinfections; sometimes they would be pushedfrom the nestsand left to die. Wasielewskireports an epidemicwhich caused severelosses in his stockof experimentaleanafies. Observationsof the presentwriter on the diseasein HouseSparrows may be summarizedas follows. Nestlingsand juvenilesin Nature are heavily infectedwith Coeeidia. Althoughthe daily dischargeof enormousnumbers of sporesmust certainly destroy large numbers of intestinal cells, many young birds survive their initial infectionswithout apparent discomfort. Perhapssome do succumbto eoeeidiosis.Unless brought to our attention in epidemicform eoeeidiosismight go unnoticedas a "natural" causeof death for birds in Nature. There is certainly sufficientevidence, however, indicating that it can be a fatal diseaseunder certain conditions. For ex- ample, in juvenile and adult sparrowswhich normally maintain chronic infections,apparently indefinitely,fatal infectionscan readily be induced by feedingheavy suspensionsof infectire spores. On the fifth or sixth day after inoculation, the bird exhibits characteristicsymptoms. The feathersare fluffedout; the head is kept under the wing much of the time. There is weaknessof the legsresulting in a squatting position,loss of ap- petite, and a drop in body temperature. When cagedwith others,an inocu- lated bird is irritable and peeks viciously at its fellows when disturbed. Death usually occursabout the seventhday after inoculation. An English Sparrowsix days after inoculationis shownin Figure 5 (Plate 31). This bird died two days later. Under ordinaryconditions in Nature, birds are not likely to ingestat one time suchlarge numbersof infectire sporesas are given in these fatal, experimentalinoculations. However, further investigationis requiredto determineto what extent natural conditions may permit the developmentof fatal infections. Passefineeoeeidiosis differsfrom poultry eoeeidiosis(and avlan malaria also)in that relatively little resistanceto subsequentinfection is built up duringthe first infection of the young bird. Figure 6 (Plate 31) showsa typical sectionof the upperintestine of a naturally infectedsparrow killed late in the summerof its first year. The Coeeidia are visible as dark, rounded bodies within the epithelial cells; there is no evidenceof tissueresponse. Most of the parasitesshown in Figure 6 are maerogametoeytes('female forms') at the characteristicstage for 3 p.m., at whichtime the hostwas killed. Had their normalgrowth Vol.1937 54]J BOUGHTON,Noteson Arian Coccidiosis 503 and developmentbeen permitted to continue,these forms would have been dischargedin the feeal material about 6 p.m. as sporeslike thoseshown in Figure 1. Chronic infections are common in domesticcanaries, and as such are potential sourcesof trouble. In small pet shopsin severalcities of the United States and in several research laboratories, the writer has found from 15 to 50 per centinfection among canaries. In 1930,through the co- operationof the R. T. French Company,the writer was able to examine feeal samplesof a few privately ownedcanaries. Ten per cent showed ooeystsof Isos29,ora.The birds were individualpets and had received routine care in the homefor a year or more prior to the examination. Unfortu- nately, the phenomenonof daily periodicityin the appearanceof ooeysts wasnot knownwhen this surveywas made, and hencethe sampleswere not taken at the most appropriate'time of day. However, it is evident that canariescan maintain chronic infectionsfor considerableperiods under averagecare in private homes. The mostlikely explanationof this condi- tion is that birds reinfeet themselves from time to time with small numbers of infectire spores,in spite of the daily cleaningof easefloor and perches. The sporesof Isos29orafrom birdsare probablyinfectire
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