Extra-intestinal coccidiosis in the kiwi (Apteryxspp.)

Abstract

Despite significant conservation intervention, the kiwi (Apteryx spp.) is in serious population decline. To increase survival in the wild, conservation management includes rearing of young birds in captivity, safe from introduced mammalian predators. However, an increase in density of immunologically naïve kiwi increases the risk of exposure to disease, including coccidia. Intestinal coccidiosis has recently been described in the kiwi, and although extra-intestinal coccidiosis was first recognized in kiwi in 1978, very little is known about this disease entity. This study used archived histological tissues and reports from routine necropsies to describe the pathology of naturally occurring extra-intestinal coccidiosis. At least 4.5% of all kiwi necropsied during 1991 to 2011 (n0558) were affected by extra-intestinal coccidiosis, and it is estimated that it caused death in 0.9 to 1.2% of kiwi in the study group. Four forms were recognized: renal, hepatic, and, less commonly, splenic and pulmonary. At necropsy, renal coccidiosis was associated with miliary white streaks and foci through the kidneys, renomegaly, and renal pallor or congestion. Renal meronts and gametocytes were confined to the distal convoluted tubules and collecting ducts, and were associated with renal tubular necrosis and tubular obstruction. Hepatic miliary pinpoint foci were present throughout the hepatic parenchyma associated microscopically with macromeronts measuring 304 )227 mm. In two cases, clusters of splenic meronts were identified, and a similar lesion was identified in the pulmonary interstitium of another case. Juvenile, captive kiwi were most often affected with extra-intestinal coccidiosis, illustrating an increased expression of disease with population manipulation for conservation purposes.

IMAGING DIAGNOSIS—USE OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY IN THE DIAGNOSIS OF A MINERALIZED YOLK SAC IN A BROWN KIWI (APTERYX MANTELLI)

“…The Brown Kiwi is a flightless bird endemic to New Zealand and is one of five species of kiwi classified as threatened with extinction . A New Zealand conservation management program based on rearing chicks in controlled environments has increased their chance of survival to adulthood to 65% compared to less than 5% in kiwi from unmanaged wild populations.In a recent study involving 406 kiwi chicks raised in captivity, 4.3% of them presented with retained or infected yolk sacs .…”

Palaeognathae: Apterygiformes, Casuariiformes, Rheiformes, Struthioniformes; Tinamiformes

“…Additionally, asexual stages of unknown coccidial species have been found in the liver, spleen, lung, and pancreas. Periodic acid Schiff staining of kidney to enhance parasite recognition is recommended as part of routine histopathologic examination (Morgan et al, 2013). Eimeriosis has also been described in red-winged tinamous.…”

Molecular characterisation and additional morphological descriptions of Eimeria spp. (Apicomplexa: Eimeriidae) from brown kiwi (Apteryx mantelli Bartlett)

“…Unfortunately, due to a build-up of environmentally resilient Eimeria spp. oocysts (Apicomplexa: Eimeriidae, Schneider 1875) and increased density of immunologically naïve hosts in Operation Nest Egg (ONE) facilities, the juvenile brown kiwi suffer morbidity and mortality delaying the programme’s ability to release kiwi into the wild (Williams, 2001 ; Yabsley, 2008 ; Morgan et al, 2012 ; Morgan et al, 2013 ). Although, coccidia infections of kiwi were first reported in the 1970s, in-depth, morphological descriptions of oocysts and endogenous stages were not described until more recently.…”

“…Morgan et al ( 2017 ) provided descriptions of four species ( Eimeria mantellii , E. kiwii , E. paraurii , E. apteryxii ) from sporulated oocysts shed by six captive brown kiwi from two ONE sites. Other reports of coccidia in kiwi include four unsporulated morphotypes described by Thompson and Wright ( 1978 ); three morphologically distinct gametocytes found in the intestinal tract (Morgan et al, 2012 ); one gametocyte reported in the renal system; and meronts in multiple visceral organs (Morgan et al, 2013 ). These reports likely overlap, describing stages of the same morphotype; however, these connections require further verification.…”

“…Accurate detection of coccidia in individual birds provides vital information regarding treatment and control of disease within kiwi rearing facilities. More detailed identification of coccidia to a species level would enable key insights for management of disease within and between kiwi populations, including issues such as treatment efficacy; translocation of disease between populations; and determination of pathogenicity of individual parasite species (Morgan et al, 2013 ; Morgan et al, 2014 ; Taylor et al, 2019 ). When, for example, a brown kiwi tests positive for a particular species of Eimeria that is known to be highly pathogenic, decisions around management can be made.…”