Pathogenesis: Small infestations may have no obvious effect on the animal; large infestations may cause accumulation of mucus in the trachea and bronchi, leading to coughing and respiratory difficulties, air saculitis and weight loss. Balance may be affected in infested birds. Weakness, emaciation and death have been described with heavy infections.

Clinical signs: Coughing, respiratory difficulties, pulmonary oedema, weight loss, loss of balance or coordination.

Diagnosis: Positive diagnosis is only possible at postmortem, when necropsy reveals white spots on the surface of air sacs.

Pathology: Death is usually associated with peritonitis, enteritis, emaciation and respiratory complications.

Epidemiology: Infestation may be spread through coughing.

Treatment: Treatment with topical moxidectin every 3 weeks as necessary may be effective.

PARASITES OF THE CIRCULATORY SYSTEM

Leucocytozoon marchouxi

Synonym: Leucocytozoon turtur

Predilection site: Blood

Parasite class: Sporozoasida

Family: Plasmodiidae

Description: Macrogametes are rounded or elliptical, stain dark blue with Giemsa and have a compact, reddish nucleus. This species forms rounded megaloshizonts in nearly all internal organs.

Hosts: Pigeons and doves

Life cycle: Sporozoites are introduced into a new host by the feeding insects. Parasites undergo merogony in the endothelial cells of internal organs forming megaloschizonts. These lead to the production of gametocytes in the blood, which, after ingestion by the vector insect, form zygote and oocysts. These undergo sporogony leading to the formation of sporozoites, which pass to the salivary glands and are introduced to the new host when the insect vectors feed.

Geographical distribution: Worldwide

Pathogenesis and clinical signs: Until recently this species was considered non-pathogenic in pigeons and doves but the species has been shown to be pathogenic to pink pigeons (Columba mayeri).

Diagnosis: Demonstration of gametocytes in blood smears

Epidemiology: Vectors are members of the genus Simulium (blackflies).

Treatment and control: Not usually required although general insect control or preventative measures may limit infection.

Haemoproteus columbae

Predilection site: Blood

Parasite class: Sporozoasida

Family: Plasmodiidae

Description: Macrogametes and microgametes present in erythrocytes range from tiny ring forms to elongate crescent-shapes that curve around the host cell nucleus in the form of a halter. Macrogametes stain dark blue with Giemsa stains, the nucleus is red to dark purple and compact, and pigment granules are dispersed throughout the cytoplasm.

Hosts: Domestic and wild pigeon, dove and other wild birds

Life cycle: Sporozoites in the salivary gland of the fly enter the circulation of the host when the insect bites and penetrate endothelial cells of blood vessels where they develop into meronts forming 15 or more cytomeres, each producing large numbers of merozoites. When merozoites are mature they are released into the circulation as tiny round bodies which transform into macrogametes and microgamonts within erythrocytes. Further development takes place in the insect host after blood feeding. After fertilisation, a zygote forms in the insect midgut where sporogony takes place, forming sporozoites. These are liberated in the body cavity and pass to the salivary glands.

Geographical distribution: North America

Pathogenesis and clinical signs: Generally considered to be of low pathogenicity in adult birds, but an acute form of infection has been reported in sqabs. Clinical signs included anorexia and anaemia.

Diagnosis: Demonstration of gametocytes in blood smears

Epidemiology: Vectors are hippoboscid flies, Pseudolynchia.

Treatment and control: Not usually required although general insect control or preventative measures may limit infection

Haemoproteus sacharovi

Predilection site: Blood

Parasite class: Sporozoasida

Family: Plasmodiidae

Description: Macrogametes and microgametes are present in erythrocytes and completely fill the host cell when mature, distorting and pushing the nucleus to one side. Pigment granules are sparse compared with other species.

Hosts: Domestic pigeon, dove

Pathogenesis: Low pathogenicity although there have been reports of hepatomegaly in sqabs.

All other details are essentially similar to H. columbae although the vector(s) have not been identified.

PARASITES OF THE NERVOUS SYSTEM

No parasites of veterinary significance.

PARASITES OF THE REPRODUCTIVE/UROGENITAL SYSTEM

No parasites of veterinary significance.

PARASITES OF THE LOCOMOTORY SYSTEM

Toxoplasma gondii

See Chapter 7 (Poultry and gamebirds), for more details.

PARASITES OF THE INTEGUMENT

Laminosioptes cysticola

Common name: Subcutaneous mite, fowl cyst mite

Predilection site: Subcutaneous tissues, lung, perotoneum

Parasite class: Arachnida

Sub-class: Acari

Order: Acariformes

Sub-order: Sarcoptiformes (Astigmata)

Family: Laminosioptidae

Description, gross: Laminosioptes cysticola is a small, oval mite, approximately 250 μm in length (Fig. 7.46).

Description, microscopic: The posterior two pairs of legs end in a claw and suckerless pedicels, while the anterior two pairs of legs end in claws. This mite has a smooth, elongated body and few setae. The gnathosoma is small and not visible when viewed from above.

Hosts: Chicken, turkey and pigeon, occasionally in wild birds

Life cycle: The life cycle is typical: egg, hexapod larva, followed by octopod protonymph, tritonymph and adult. All developmental stages occur on the host. However, life cycle details are lacking. The mites are found in the subcutaneous muscle fascia and in deeper tissues in the lungs, peritoneum, muscle and abdominal viscera.

Geographical distribution: Worldwide. It is abundant in Europe and is also found in the United States, South America and Australia.

Pathogenesis: Laminosioptes is not usually associated with clinical signs and is only discovered in pigeons at postmortem. Active mites occur in the deep tissues. The nodules created by the mites reduce the value of meat intended for human consumption.

Clinical signs: The parasites are not usually regarded as pathogenic.

Diagnosis: The nodules may be seen in living birds by parting the breast feathers and sliding the skin back and forth with the fingertips. Examination of the nodules under a dissection microscope usually allows the identification of the mite species.

Pathology: Aggregations of these small, oval mites are found in yellow nodules, several millimetres in diameter, in the subcutaneous muscle fascia and in deeper tissues in the lungs, peritoneum, muscle and abdominal viscera. The subcutaneous nodules are often calcified, but these only contain dead mites as the calcareous deposits are produced around the mites after they have died.

Epidemiology: It is estimated that around 1% of free-living urban pigeons harbour Laminosioptes cysticola. The mode of transmission of this mite is unknown.

Treatment: Macrocyclic lactones may be effective.

Control: Destroying or quarantining the infected birds may be required to achieve long-term reduction in infestations within a flock.

ECTOPARASITES

Colombicola columbae

Common name: Slender pigeon louse

Predilection site: Wings or anterior part of the body

Parasite class: Insecta

Parasite order: Phthiraptera

Parasite sub-order: Ischnocera

Family: Philopteridae

Description: A pale yellow, slender louse usually 2–3 μm in length.

Hosts: Pigeons and doves

Life cycle: Eggs of this species are usually attached to the feathers close to the skin. There are three nymphal stages similar to, although much smaller than, the adult. Development of the final stage gives rise to the fully mature reproductive adult.

Geographical distribution: Probably worldwide

Pathogenesis: Infection may cause a mild pruritus, and in common with most pediculoses, heavy infestations are usually seen only in diseased and debilitated birds causing feather damage and irritation.

Clinical signs: Feather damage and irritation

Diagnosis: Adult lice may be seen moving around the plumage or eggs may be seen attached to feathers.

Pathology: Lice are rarely linked to significant pathology.

Epidemiology: Infection occurs after direct contact with an infested host animal. Cross-contamination between different host species is possible if the animals have physical contact.

Treatment: Topical insecticidal compounds, such as permethrin, carbaryl, malathion, cypermethrin or rot-enone, can be used to kill lice. However, as the insecticides are unable to kill the eggs, two applications are necessary with a 10-day interval.

Control: Although methods such as dusting the litter or providing insecticide-treated laying boxes are used to avoid undue handling of birds, the results obtained from treating individual birds are undoubtedly better. Regular checking and spraying of birds will enable infestation rates to be controlled. In addition, crosscontamination should be avoided. This is achieved by treating any birds in the environment of the pigeons and restricting contact between wild birds and pigeons. The housing and nesting should be thoroughly cleaned to eliminate sources of reinfestation such as egg-laden feathers.

Pseudolynchia canariensis

Common name: Pigeon fly

Predilection site: Skin

Parasite class: Insecta

Family: Hippoboscidae

Description: Adult flies are approximately 10 mm in length and are generally pale reddish brown with yellow spots on the indistinctly segmented abdomen. They have one pair of wings, the veins of which are crowded together towards the anterior margin. Both sexes of adult are blood feeders. The larvae are rarely seen and measure about 5 mm in length.

Hosts: Mainly pigeons but other domestic birds may also be infested.

Life cycle: Gravid female flies mature larvae singly. Each female can produce only five or six larvae in its lifetime. These larvae pupate almost immediately after larviposition. When pupation is completed, the newly emerged winged adults locate a suitable host animal on which they blood-feed, remaining on the host for long periods. In temperate areas, flies are most abundant in the summer months.

Geographical distribution: Worldwide

Pathogenesis: The adult flies bite and blood-feed, resulting in a nuisance and disturbance. Heavily infested birds may be restless, emaciated and become susceptible to secondary infections. They may act as vectors of Haemoproteus columbae and H. sacharovi.

Clinical signs: The adult flies are clearly visible when feeding on the host animal. Irritation at the feeding sites may be observed.

Diagnosis: The adult flies may be found on the host animal.

Epidemiology: The adult flies are most abundant on the host during the summer months.

Treatment and control: This is best achieved by topical application of insecticides, preferably those with some repellent and residual effect such as the synthetic pyrethroids, permethrin and deltamethrin.

Ceratophyllus columbae

Common name: Pigeon flea

Predilection site: Skin

Parasite class: Insecta

Parasite order: Siphonaptera

Family: Ceratophyllidae

Description: Adults of Ceratophyllus columbae are typically 2–2.5 mm long with no antennal fossae. Eyes are present. There is a pronotal comb carrying more than 24 teeth, while the genal comb is absent. There is a lateral row of four to six bristles on the inner surface of the hind femur, and there are no spines on the basal section of the legs. Detailed description of individual species in this genus is beyond the scope of this text.

Hosts: Pigeon

Life cycle: The life cycle is typical: egg, three larval stages, pupa and adult. Before the female can begin ovipositing it needs to feed on the host several times. Unlike most other fleas, which often remain on the host and feed for long periods, pigeon fleas spend most of their time in the nest of the host, and only move on to the birds to feed for short periods.

The larvae feed on detritus amongst the nest material, bird droppings and on undigested blood from the adult faeces. The larval stages are completed in a few weeks, before the pupal cocoon is spun. The flea overwinters in the cocoon and emerges in an old nest in spring as temperatures rise. Large numbers may occur in the nests of passerine birds, and they may complete their life cycle during the period of nest occupation by these birds. Work has shown a negative correlation between flea abundance and mean body mass of the brood being parasitised.

If the nest is reused by birds the following year, the newly emerged adults will locate the new hosts, feed and continue the cycle. If the nest is not reused, the newly emerged adults will make their way to the nest entrance, where they may be able to attach to a bird that is examining the old nest as a potential nest site. Alternatively, they may climb up trees and bushes, where they stop periodically and face the brightest source of light, jumping in response to a shadow passing in front of the light.

Geographical distribution: Found predominantly in the Old World, but has been introduced into the Americas.

Pathogenesis: Feeding activity may cause irritation, restlessness and, with heavy infestations, anaemia. In wild birds, flea reproduction and feeding activity is synchronised with the breeding season. Adult C. columbae may also feed on humans and domestic pets.

Clinical signs: Symptoms include restlessness and scratching of affected areas. The bites may be visible on the skin. Allergic dermatitis may be seen.

Diagnosis: Diagnosis is not easy as adults may leave the host and eggs and larvae are difficult to find. The bites of these fleas are similar to those of mosquitoes, lice and mites, with inflammation and itchiness.

Epidemiology: These fleas are not host specific and may attack any available mammal or bird for a blood-meal. As they are able to survive off the host, transmission can occur from the bedding and housing. This flea is highly mobile on the host and can be especially common in host nesting material. Ceratophyllus columbae feeds readily on humans and domestic pets, and is often acquired in the handling of pigeons and wild birds. It has also been known to migrate into rooms from nests under adjacent eaves. When such nests are removed they should be incinerated; otherwise the underfed fleas may parasitise domestic pets and humans.

Treatment: Topical treatment of the affected birds with insecticidal products such as permethrin, carbaryl, malathion and rotenone is effective.

Control: Should fleas become established, drastic measures may have to be adopted to get rid of them. All litter and nest material should be removed and burnt, and the housing sprayed with an insecticide.

Argas reflexus

Common name: Pigeon tick

Predilection site: Skin

Parasite class: Arachnida

Sub-class: Acari

Order: Parasitiformes

Sub-order: Ixodida (Metastigmata)

Family: Argasidae

Description: Species of the genus are usually dorsoventrally flattened, with definite margins, which can be seen even when the tick is engorged. The cuticle is wrinkled and leathery. Most species are nocturnal and are parasites of birds, bats, reptiles or, occasionally, small insectivorous mammals. Most species seldom attack humans. Species of this genus are usually found in dry, arid habitats.

The adult Argas reflexus is between 6 and 11 mm in length. It may be distinguished from the fowl tick, Argas persicus, by its body margin, which is composed of irregular grooves, and by the hypostome, which is not notched apically. It is reddish brown in colour with paler legs.

Hosts: Birds, mainly pigeons

Life cycle: Argas reflexus is nocturnal and breeds and shelters in cracks and crevices in the roost structure. Females deposit batches of 50–100 eggs in these cracks and crevices. After hatching, larvae locate and attach to a host, where they remain and feed for several days. After feeding they detach, leave the host and shelter in the pigeon lofts or roosts. Several days later they moult to become first-stage nymphs. They then proceed through two nymphal stages, interspersed with frequent feeds, before moulting to the adult stage. Adult males and females feed about once a month. Females can become completely engorged within 30–45 minutes. All stages of these ticks remain around the roosting area, quiescent in the day and actively feeding at night. Argas reflexus can survive in empty roosts for more than a year. Engorged females diapause between July and August. If oviposition has already commenced, egg-laying stops and resumes the following year without the need for another blood meal.

Geographical distribution: Europe, Russia, Asia, north and west Africa.

Pathogenesis: Infestation may cause irritation, sleeplessness, loss of egg productivity and anaemia, which can prove fatal. Heavy infestations can take enough blood to bring about the death of their host. This species transmits Borrelia anserina, the cause of fowl spirochaetosis, and Aegyptianella pullorum, a rickettsial infection. It may also be a vector of west Nile and chenuda virus and the quaranfil virus group.

Clinical signs: Inflammation and raised areas will be present from tick bites. Larvae may be found living in the feathers. These ticks can cause sleeplessness, loss of productivity and anaemia, which can prove fatal.

Diagnosis: The adult ticks, particularly the engorged larvae, may be seen on the skin. Nymphs and adult ticks may be found in cracks of the woodwork. Red spots may be seen on the skin where the ticks have fed.

Pathology: Small granulomatous reactions may form at the site of tick bites consisting of a mixed inflammatory cell response with fibrosis.

Epidemiology: Argas reflexus eggs show limited levels of cold tolerance; winter temperatures of 3°C cause approximately 50% mortality. This limits its northern distribution through Europe.

Treatment: Argasid ticks, which exist in lofts and enclosures, can be controlled by application of an acaricide to their environment coupled with treatment of the population on the host. Environmental treatment of roosts and lofts may be effected using acaricidal sprays or emulsions containing organophosphates or pyrethroids. All niches and crevices in affected buildings should be sprayed, and nesting boxes and perches should also be painted with acaricides. At the same time as premises are treated, birds should be dusted with a suitable acaricide or, in the case of larger animals, sprayed or dipped. Treatment should be repeated at monthly intervals.

Control: All new animals should be treated prior to introduction into an existing flock.

RATITES (OSTRICH, RHEA, EMU)

PARASITES OF THE DIGESTIVE SYSTEM

PROVENTRICULUS, GIZZARD

Libyostrongylus

Life cycle: The life cycle is typically strongyle. Following ingestion, infective larvae burrow into the proventricular glands and under the kaolin layer of both proventriculus and gizzard where they develop into adult worms 4–5 weeks later

Pathogenesis: The young worms penetrate deeply into the mucosa of the glands of the proventriculus. Adults live on the surface of the epithelium (Fig. 10.2) where they feed on blood, causing a severe inflammatory reaction and anaemia.

Clinical signs: Chicks are most susceptible to infection and become anaemic, weak and emaciated with heavy mortality in untreated cases.

Fig. 10.2 Libyostrongylus douglassi: mucosal surface of proventriculus. Insert shows magnified worm.

Diagnosis: Diagnosis is based on finding eggs in the faeces or by identifying the worms in the proventriculus and gizzard on postmortem.

Treatment: Levamisole (30 mg/kg), fenbendazole (15 mg/kg) and ivermectin (200 μg/kg) are effective in the treatment of wireworm infection in young ostrich.

Control: Appropriate hygiene and husbandry measures, including removal of faeces aimed at limiting pasture contamination, help limit exposure to dangerous levels of infective larvae. It is important to isolate and treat all new birds to prevent introduction of infection on ostrich farms.

Libyostrongylus douglassi

Common name: Wireworm

Predilection site: Proventriculus, gizzard

Parasite class: Nematoda

Superfamily: Trichostrongyloidea

Description, gross: Small yellowish red nematodes; males 4–6 mm and females 5–6 mm

Description, microscopic: The male bursa is well developed; the dorsal ray is long and split in its distal half forming three small branches either side. The spicules each end in a large and small spine. Eggs measure 59–74 × 36–44 mm. Third-stage larvae are characterised by a small knob at the tip of the tail.

Hosts: Ostrich

Geographical distribution: Africa, North America, Europe

Libyostrongylus dentatus

Common name: Wireworm

Predilection site: Proventriculus, gizzard

Parasite class: Nematoda

Superfamily: Trichostrongyloidea

Description, gross: Males 6–8 mm and females 10–12 mm

Description, microscopic: There is a prominent dorsal oesophageal tooth. There is a large bursa; the dorsal ray is long and bifurcated extending into a rounded lobe of the bursal membrane. A spicule with dorsal process arises two thirds from the anterior and the main shaft ends in a rounded point capped by a hyaline sheath.

Hosts: Ostrich

Geographical distribution: Africa, North America

Spiruroid nematodes

Several species of spiruroid worms belonging to the genera Spiura and Odontospiura are found in the proventriculus of rheas. These species are essentially similar to spiruroid worm species found in the proven-triculus of poultry (see Chapter 7). The identification of individual species is beyond the scope of this book and interested readers will need to consult a relevant taxonomic specialist. Diagnosis is based on the presence of spiruroid eggs in the faeces or the presence of the worms in the proventriculus on postmortem.

Spiruria uncinipenis

Synonym: Sicarius uncinipenis

Predilection site: Proventriculus

Parasite class: Nematoda

Superfamily: Spiruroidea

Description, gross: Males measure 15–20 mm and females 16–26 mm.

Description, microscopic: The spicules are short and unequal in length.

Final hosts: Rhea

Geographical distribution: South America

Spiruria zschokkei

Synonym: Vaznema zschokkei

Predilection site: Proventriculus

Parasite class: Nematoda

Superfamily: Spiruroidea

Description, gross: Males measure 16–17 mm; female worms are 17–25 mm in length.

Description, microscopic: The spicules are long and filiform.

Final hosts: Rhea

Geographical distribution: South America

Odontospiruria cetiopenis

Predilection site: Proventriculus, gizzard

Parasite class: Nematoda

Superfamily: Spiruroidea

Description, gross: Males measure 15–17 mm; female worms are 20–23 mm.

Final hosts: Rhea

Geographical distribution: South America

SMALL INTESTINE

Deletrocephalus dimidiatus

Predilection site: Small intestine

Parasite class: Nematoda

Superfamily: Strongyloidea

Description, gross: Adult worms are stout and robust with a well developed buccal capsule. Male worms are 9–11 mm and females 14–16 mm long.

Description, microscopic: Males are bursate with long, thin spicules. The eggs are 160 × 70 μm. Third-stage larvae are approximately 720 μm long with a rounded head, 28–31 intestinal cells and a short to medium tail.

Final hosts: Greater rhea (Rhea Americana), lesser rhea (Pterocnemia pennata)

Life cycle: The life cycle is thought to be direct, with birds ingesting infective larvae whilst foraging.

Geographical distribution: South America, North America, Europe

Pathogenesis and clinical signs: There are limited reports on the distribution and pathogenicity of this parasite in rheas. The parasite has become established in domesticated rheas and has been reported to cause weak, diarrhoeic chicks in heavy infections.

Diagnosis: Diagnosis is based on finding eggs in the faeces or by identifying the worms in the intestine on postmortem.

Treatment and control: There is little information on the treatment of this parasite in rheas. Benzimidazoles and ivermectin have been used in the treatment of nematodes in ostrich, and therefore may be of benefit. Rearing of chicks away from adult birds and regular cleaning of pens may help limit infection.

Paradeletrocephalus minor

Predilection site: Small intestine

Parasite class: Nematoda

Superfamily: Strongyloidea

Description, gross: Adult worms are similar in size to Deletrocephalus spp.

Description, microscopic: The buccal capsule has vertical ridges and there are no external or internal coronary rings.

Final hosts: Greater rhea (Rhea Americana), lesser rhea (Pterocnemia pennata)

Geographical distribution: South America

Hottuynia struthionis

Predilection site: Small intestine

Parasite class: Cestoda

Family: Davaineidae

Description, gross: These are large tapeworms (60–120 cm).

Description, microscopic: The scolex is 1–2 mm wide and bears a double row of about 160 large and small hooks. Genital pores are unilateral.

Final hosts: Ostrich, rhea

Life cycle: The life cycle is unknown.

Geographical distribution: Africa, South America

Pathogenesis: The tapeworm is seen especially in ostrich chicks but has also been reported in rheas, causing unthriftiness, emaciation and diarrhoea.

Clinical signs: Affected chicks lose their appetite and may die.

Diagnosis: Diagnosis is based on finding eggs in the faeces or by identifying the worms in the proventriculus and gizzard on postmortem.

Treatment: Praziquantel at 7.5 mg/kg is effective.

Control: As the intermediate host is not known, specific control measures are not possible. Rearing of chicks away from adult birds, regular cleaning of pens and insect control would seem expedient.

LARGE INTESTINE

Codiostomum struthionis

Predilection site: Large intestine

Parasite class: Nematoda

Superfamily: Strongyloidea

Description, gross: These strongylid worms are 13–17 mm in length.

Description, microscopic: The large buccal capsule is sub-globular with external and internal leaf crowns but no teeth. The male bursa has a large projecting dorsal lobe.

Hosts: Ostrich

Life cycle: The life cycle is unknown.

Geographical distribution: Africa

Pathogenesis and clinical signs: Potentially a pathogenic worm causing anaemia and poor growth rates.

Diagnosis: The eggs are identical to L. douglassi and diagnosis is based on identification of the adult worms in the caeca and colon.

Treatment and control: As for Libyostrongylus

Trichostrongylus tenuis

Predilection site: Small intestine, caeca.

Parasite class: Nematoda

Superfamily: Trichostrongyloidea

Hosts: Game birds (grouse, partridge and pheasant), chicken, duck, goose, turkey, emu

Geographical distribution: North America, Asia and Europe

Epidemiology: A common parasite of various galliform and anseriform birds

For more details see Chapter 7 (Poultry and game–birds).

Other parasites reported in the intestines of ratites are listed in the parasite checklist at the end of this chapter.

PARASITES OF THE RESPIRATORY SYSTEM

Paronchocerca struthionis

Predilection site: Pulmonary arteries, lungs

Parasite class: Nematoda

Superfamily: Filarioidea

Description, gross: Long abursate nematodes, 3–5 cm in length with bluntly rounded extremities.

Description, microscopic: Male spicules are dissimilar in length; a gubernaculum is absent. Microfilariae are 100–125 μm long with a rounded posterior extremity.

Hosts: Ostrich

Geographical distribution: Africa

Pathogenicity: Not reported

Syngamus trachea

Common name: Gapeworm

Predilection site: Trachea

Parasite class: Nematoda

Superfamily: Strongyloidea

Hosts: Chicken, turkey, game birds (pheasant, partridge, guinea-fowl), various wild birds

Geographical distribution: Worldwide

For more details see Chapter 7 (Poultry and gamebirds).

Cyathostoma variegatum

Common name: Gapeworm

Predilection site: Trachea, bronchi

Parasite class: Nematoda

Superfamily: Strongyloidea

Description, gross: Adult worms are 0.4–3 cm long; males are 4–5.8 mm and females 16–31 mm.

Description, microscopic: The buccal capsule is cupshaped with six to seven teeth at its base. The male bursa is well developed but worms in this species are not permanently in copula, which contrasts to the situation with Syngamus trachea. Eggs are 74–83 × 49–62 μm.

Hosts: Duck, emu

Life cycle: The life cycle is thought to be similar to that of Syngamus

Geographical distribution: Australia

Pathogenicity: Has been reported to cause severe respiratory distress in young emus.

Epidemiology: A number of paratenic hosts may be involved in transmission.

Treatment and control: Ivermectin is likely to be effective.

PARASITES OF THE CIRCULATORY SYSTEM

Leucocytozoon struthionis

Predilection site: Blood

Parasite class: Sporozoasida

Family: Plasmodiidae

Description: Gamonts are round and present within erythrocytes

Final host: Ostrich

Intermediate host: Blackflies (Simulium)

Geographical distribution: Africa

Pathogenesis and clinical signs: Thought to be of low pathogenicity although it has been found in association with myocarditis in young ostrich chicks and may cause anaemia during early parasitaemia.

Epidemiology: A common parasite of ostrich chicks in South Africa transmitted by blackflies, Simulium

Diagnosis: Identification of either gamonts in blood or megalomeronts in tissue.

Treatment and control: Not reported

Plasmodium struthionis

Predilection site: Blood

Parasite class: Sporozoasida

Family: Plasmodiidae

Pathogenesis: Reported in ostrich as causing an asymptomatic low, chronic parasitaemia.

PARASITES OF THE NERVOUS SYSTEM

No parasites of veterinary significance reported.

ECTOPARASITES

Struthiolipeurus struthionis

Common name: Ostrich louse

Predilection site: Feathers and skin

Parasite class: Ischnocera

Family: Philopteridae

Description: Narrow-bodied louse with a large head (Fig. 10.3)

Hosts: Ostrich

Fig. 10.3 Struthiolipeurus struthionis (photograph courtesy of Dr Vince Smith).

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