Hepatozoon kiwii, PEIRCE & JAKOB-HOFF & TWENTYMAN, 2003

PEIRCE, M. A., JAKOB-HOFF, R. M. & TWENTYMAN, C., 2003, New species of haematozoa from Apterygidae in New Zealand, Journal of Natural History 37 (15), pp. 1797-1804 : 1800-1802

Hepatozoon kiwii sp. nov.

(figures 15–18)

Parasite. Hepatozoon kiwii sp. nov.

Type host. Apteryx australis mantelli Bartlett.

Type locality. Purua , North Island, New Zealand .

Vector. Possibly Ixodes anatis Chilton.

Hapantotype. IRCAH: G463170 from Apteryx australis mantelli , coll. Twentyman, 7 April 2000, Auckland Zoo , New Zealand . Deposited in International Reference Centre for Avian Haematozoa, Queensland Museum, Brisbane, Australia .

Parahapantotypes. IRCAH: G463171 from Apteryx australis mantelli , coll. Twentyman, 7 April 2000, Auckland Zoo , New Zealand ; IRCAH: G463172 from Apteryx australis mantelli , coll. Jakob-Hoff, 29 September 2000, Auckland Zoo , New Zealand . Deposited in International Reference Centre for Avian Haematozoa, Queensland Museum, Brisbane, Australia .

Distribution. Probably occurs throughout New Zealand with potential to infect all species of Apterygidae .

Description. The gametocytes (figures 15–18) are found in mononuclear leucocytes, usually monocytes but also lymphocytes. A capsule seen as a white halo around the parasite is more prominent in immature forms. The host cell nucleus becomes distorted and compressed to the periphery where it forms a cap and the whole cell becomes hypertrophied as the parasite matures. In some cells the mature parasite causes the host cell nucleus to be expelled (figure 18). Gametocytes are generally oval or elongate in shape with rounded ends. Occasionally, forms are seen in which a mature elongate gametocyte is folded and a central cleavage separating the two sides is clearly visible (figure 15). The cytoplasm is granular, staining a pale to deep pink and containing small round volutin-like granules or pseudo-pigment which are often stained a deep red. The gametocyte nucleus is round to oval in shape and stains slightly darker than the cytoplasm; the position within the gametocyte varies; a dark staining karyosome is often visible. The gametocytes measure 9.83–13.53× 6.25–8.31 m m (mean 11.73× 7.05 m m) (N =31). The nucleus measures 4.72–5.52× 1.71–3.43 m m (mean 4.89× 2.8 m m).

Comments. The single bird so far found to be infected with Hepatozoon kiwii sp. nov. was first observed to present a patent parasitaemia in April 2000 and parasites could still be detected in the blood in May, August and September, albeit in reduced numbers. Thus, as with B. kiwiensis the presence of H. kiwii in peripheral blood maintains a chronic phase for some time. There is no evidence to indicate that H. kiwii is pathogenic in the host but as a concomitant infection with B. kiwiensis or other disease agents it may contribute to chick morbidity. Studies are continuing to determine the life cycle of the parasite and to investigate the possibility that I. anatis is the vector.