Blood Parasites of Animals in New Zealand

Blood parasites of animals in New Zealand

New Zealand is relativelv free from blood-borne Darasites. when within the blood stream at certain times compared to overseas countries. This freedom is due to the fact that of the day, and are transmitted by biting insects to another host, Species New Zealand is also free from many ticks and biting insects vectors Dirofi/aria, DiDeto[rlnema,Parafilaria and associated with transmission of such parasites('). Haemophysalis Elaeophora(2'. longicornis is the only endemic tick and it is found in the warmer regions of New Zealand('). Routine surveillance of blood smears from all species of animals, is carried out by MAF Quality Management regional animal health laboratories and Alpha Scientific Ltd.

Blood parasites include species of protozoa, cluded in the protozoal section of parasitol- rickettsia and nematodes. Protozoa are uni- ogy textbooks'?'. However, they are in fact cellular, eukaryotic, micro-organisms and prokaryotic micro-organisms. Haemohar- while most are free living, some are parasitic tonella species and Eperthyrozoon species causing significant stock and production are very similar morphologically, the main losses in many parts of the world'2'. They in- difference being that Haemobartonella is clude the protozoal species of Babesia, very closely attached to the erythrocyte Trypanosoma, Theileria, and Cytauxzoon. membrane when compared to Eperythro- Reproductive methods vary, depending on zoon(2).Ehrlichia are small prokaryotic mi- the species and include binary fission, cro-organisms often found withln circulat- schizogony, andlor sexual reproduction. ing leucocytes of susceptible mammals. Transmission is usually by biting and suck- Transmission is by ixodid ticks. They are ing insects, and ticksi2). found either singly, or in small groups within infected cells. Rickettsia such as Anaplusma, Haernobar- Janice Thompson, author of this article tonella and Eperythrozoon were previously Some species within the Family Filaroides considered protozoa and, as such, were in- produce microfilaria which appear Endemic blood parasites in livestock

Haemobartonellu canis: This rickettsial parasite of dogs is very infrequently diagnosed in New Zealand. Overseas it is reported to be nonpathogenic, only rarely causing Infection may be associated with immunosuppression and splenectomy. Young puppies are more susceptible to infection. A recent case was diagnosed at Ruakura Animal Health Laboratory in a clinically anaemic and lethargic dog but the vector within New Zealand is unknown. Dipetulonema reconditum: D reconditum is diagnosed only rarely in dogs in the Animal Health Laboratories. The adults of this parasite reside in the tissues, but microfilaria are occasionally seen within the blood stream and need to be differentiated from Diro- filuria immitis. No pathogenic effects have been attributed to D reconditum. The prepat- ent period is 61 to 68 days and transmission is thought to be via the cat and dog fleas Ctenncephalides ,felis, C canis, and Pulex irritans. Haemobartonella felis: H felis is a very common rickettsial parasite of cats. Trans- mission is thought to occur via fleas and biting insects, but there are recent suggestions that transmission may also occur intrauterine andor via the milk. It frequently causes a re- generative anaemia. Recovered cats are thought to become chronic carriers and re- lapses may occur. Infection may also be seen

6 Surveillance 25(1) 1998 in immunosuppressed animals. The parasi- there is some controversy as to whether or D immitis (heartworm) may also affect taemia is often cyclical, and repeated blood not they are two separate species('6).Over- cats'si. smear examinations may be needed for diag- seas E suis has been associated with anae- nosis. The anaemia caused is partly immune mia and low viability of piglet^(?^("^. mediatedi?)i3)lJ) Eperythrozoon species in pigs are trans- References Theileria orientalis: This is the only mitted mechanically, by biting and suck- ing insects and also transplacentally. It is piroplasm organism found in New Zea- (1) Fairley R, Heath A. Exotic ticks inter- landi"'". It was first diagnosed in 19841x'and believed that hormonal changes associated cepted in New Zealand since 1980. since then has been diagnosed in the warmer with parturition may activate a latent or Surveillance 24(1), 21-2, 1997. areas of New Zealand where the tick H chronic infection. Other stressors involv- (2) Soulsby EJL. Helminths, arthropods and ing management practices are also thought protozoa of domesticated animals 7th longicornis, presumed to be the vector, is to affect infection and manifestation of Edition, Pp 306-21. Balliere and Tindall, found. T orientalis infection is benign, and 1982. disease""). theoretically its presence may be due to im- (3) Jain NC. Hemolytic anemias associated munosuppression caused by concurrent con- with some infectious agents. Schalm's ditionsK~1~71 Veterinary Hematology, 4th Edition, Pp Endemic blood parasites in wildlife 589-626, Lea and Febiger, Philadelphia, Eperythrozoon wenyoni: E wmyoni was 1986. first reported in New Zealand in 1977, in a Huemoproteus dunilew!sky, Leucocytozoon (4) Van Steenhouse JL, Toboada J, Millard 4-year-old Jersey cow, and parasitaemia JR. Feline hemobartonellosis. Compen- species and Plasmodium species have been dium of Continuing Education for the was then induced in a splenectomized identified in red blood cells from New Zea- Practicing Veterinarian 15, 535-45, 1993. calP"'. Two further cases were noted in land wildlife('x1i")i20'.Recently, Plasmodium (5) Holmes RA. Feline heartworm disease. North Auckland in 1977""'. Overseas stud- species have been diagnosed as causing Compendium of Continuing Education for ies showed that anaemia was usually asso- clinical infections associated with severe the Practicing Veterinarian 15, 687-95, 1993. ciated with infection. Parasitaemia was anaemia and hepatitis, and deaths in captive also seen in cattle severely affected by dotterels. The birds suffered also from a (6) Thompson J. Theileriasis in New Zealand. other diseases(31'''. Surveillance 18(5), 21 -3, 1991. concomitant pox infection (B Smits, pers (7) Fairley N. Anaemia in cattle. Surveillance Eperythrozoon ovis: E ovis is the only comm). 19(1), 18, 1992. known blood parasite of sheep in New Zea- Recently blood from a sick, anaemic possum (8) James MP, Saunders BW, Guy LA, land'""'?'. It is transmitted by biting insects, Brookbanks EO, Charleston WAG, with multiple haemorrhages, contained Uilenberg G. Theileria orientalis, a blood such as Stomoxys calcitruns. Inapparent in- small basophilic structures on the surface of parasite of cattle. First report in New fections are probably common, but it is erythrocytes which resembled H.fe1i.s in cats. Zealand. New Zealand Veterinary Journal rarely diagnosed as a primary infection. In The possum was positive for warfarin, which 32, 154-6, 1984. New Zealand, experimental infections pro- was considered the cause of the anaemia and (9) Sutton RH, Charleston WAG, Collins GH. Eperyfhrozoon wenyoni - a blood para- duced decreased weight gains and anaemia haemorrhage. The significance of the bodies in some sheep, but not in others'"l(l?'.In Aus- site of cattle. A first report in New is unknown and electron microscopy is Zealand. New Zealand Veterinary Journal tralia, infection has produced severe dis- needed to further examine the structures, 25, 8-9, 1977. ease"". It is speculated that intercurrent dis- should another affected possum be found. (10) Anonymous, Eperthyrozoonosis of cattle. ease may predispose to infection. Goats are Surveillance 4(5), 10, 1977. less susceptible to E ovis than sheep and it is (1 1) Sutton RH. Eperyfhrozoon ovis - a blood hypothesized that in goats a higher level of parasite of sheep. New Zealand Veteri- Blood parasites diagnosed in parasitaemia is required for natural spread to nary Journal 18, 156-64, 1970. imported dogs occur"-". (12) Sutton RH, Jolly RD. Experimental Eperythrozoon ovis infection of sheep. Porcine eperythrozoonosis: This parasite Diroflaria immitis: Heartworm is not en- New Zealand Veterinary Journal 21, 160- was first diagnosed in New Zealand in demic in New Zealand, but has been diag- 6, 1973. 19961'5)f1").Pigs from farms on which this nosed in imported dogs. Exotic mosquitoes (13) Mason RW, Statham P. The determina- tion of the level of Eperythrozoon ovis was diagnosed showed reproductive prob- including Culex, Aedes and Anopheles act as parasitaemia in chronically infected sheep lems, increased piglet mortality, gross intermediate hosts for the parasite"'. Devel- and its significance to the spread of vulval oedema and prolonged farrow- opment within the vectors takes about 15 to infection. Australian Veterinary Journal ing""'. The vulval oedema is not men- 17 days and because competent vectors are 68, 115-6, 1991. tioned as occurring extensively in Western not prescnt in New Zealand, infected im- (14) Mason RW, Statham P. Susceptibility of countries, but has been commonly de- sheep and goats to Eperythrozoon ovis ported animals do not transmit the disease to infection. Australian Veterinary Journal scribed in Asia. In New Zealand, organ- other animals. After infection, there is a pe- 68, 116-7, 1991. isms were seen in sows at farrowing, in riod of 85 to 120 days before the develop- (15) Fairley R, Fairley N. Further evidence that piglets born to sick sows, and large num- mental stages are found in the heart and pul- Babesia perroncitoi is not present in New bers of organisms were seen in splenect- monary artery. Mature worms and Zealand pigs. Surveillance 24(1), 32, omised piglets. Affected animals showed a microfilaria are found 2 months later. Circu- 1997. mild anaemia, thrombocytopaenia, lating microfilaria may survive for up to 2 (16) Frey B, Stevenson MA. Eperyfhrozoon infection on a large New Zealand piggery. lymphopaenia and inflammatory years and transplacental transmission may Proceedings of the Australian Association leucogram. In some animals serum bi- occur, so neonatal pups may be affected"). of Pig Veterinarians, Brisbane. Pp 54-8, lirubin concentrations were increased. At Diagnosis may be made on serology, or by 1977. this stage it is not known whether these observing microfilaria within blood smears, (17) Henderson JP, O'Hagan J, Hawe SM, were primary infections, or secondary to or on necropsy. The serological test detects Pratt MCH. Anaemia and low viability in other causes. Also, at this stage it is incon- piglets infected with Eperyfhrozoon suis. female antigen and may give a false negative The Veterinary Record 140, 144-6, 1997. clusive as to whether the species in New if only mature males are present. Micro- Zealand is E purvum or E .sui~"~'.E filaria are measured using the Knott's test, purvum is generally regarded as non- and differentiated from microfilaria of other pathogenic when compared to E suis, but species on the basis of size. Continued next page

Surveillance 25(1) 1998 7 Blood parasites of animals in New Zealand

Continuedfrom page 7

(18) Laird M. Some blood parasites of New Zealand birds. Zoological Publications 6, 1-20, 1950. (19) Graczyk TK, Cockrem JF, Granfield MR, Darby JT, Moore P. Avian malaria seroprevalence in wild New Zealand penguins. Parasite 2, 401-5, 1995. (20) Fallis AM, Bisset SA, Allison FR. Leucocyfozoon fawaki nsp. (Eucoccida: Leucocytozoidae) from the penguin Eudyptes pachyrhynchus) and preliminary development in Austrosimulium spp. (Diptera : Simuliidae). New Zealand Journal of Zoology 3, 11-6, 1976.

Juiiice Thompson MAF Quality Management Palmerston North Animal Health Laboratory Email: [email protected]

8 Surveillance 25(1) 1998