Leucocytozoon Toddi Research Articles

Avian haemosporidian parasites of accipitriform raptors

BackgroundThe order Accipitriformes comprises the largest group of birds of prey with 260 species in four families. So far, 21 haemosporidian parasite species have been described from or reported to occur in accipitriform birds. Only five of these parasite species have been characterized molecular genetically. The first part of this study involved molecular genetic screening of accipitriform raptors from Austria and Bosnia-Herzegovina and the first chromogenic in situ hybridization approach targeting parasites in this host group. The aim of the second part of this study was to summarize the CytB sequence data of haemosporidian parasites from accipitriform raptors and to visualize the geographic and host distribution of the lineages.MethodsBlood and tissue samples of 183 accipitriform raptors from Austria and Bosnia-Herzegovina were screened for Plasmodium, Haemoproteus and Leucocytozoon parasites by nested PCR, and tissue samples of 23 PCR-positive birds were subjected to chromogenic in situ hybridization using genus-specific probes targeting the parasites’ 18S rRNAs. All published CytB sequence data from accipitriform raptors were analysed, phylogenetic trees were calculated, and DNA haplotype network analyses were performed with sequences from clades featuring multiple lineages detected in this host group.ResultsOf the 183 raptors from Austria and Bosnia-Herzegovina screened by PCR and sequencing, 80 individuals (44%) were infected with haemosporidian parasites. Among the 39 CytB lineages detected, 18 were found for the first time in the present study. The chromogenic in situ hybridization revealed exo-erythrocytic tissue stages of Leucocytozoon parasites belonging to the Leucocytozoon toddi species group in the kidneys of 14 infected birds. The total number of CytB lineages recorded in accipitriform birds worldwide was 57 for Leucocytozoon, 25 for Plasmodium, and 21 for Haemoproteus.ConclusionThe analysis of the DNA haplotype networks allowed identifying numerous distinct groups of lineages, which have not yet been linked to morphospecies, and many of them likely belong to yet undescribed parasite species. Tissue stages of Leucocytozoon parasites developing in accipitriform raptors were discovered and described. The majority of Leucocytozoon and Haemoproteus lineages are specific to this host group, but most Plasmodium lineages were found in birds of other orders. This might indicate local transmission from birds kept at the same facilities (raptor rescue centres and zoos), likely resulting in abortive infections. To clarify the taxonomic and systematic problems, combined morphological and molecular genetic analyses on a wider range of accipitriform host species are needed.

The nuclear 18S ribosomal DNAs of avian haemosporidian parasites

BackgroundPlasmodium species feature only four to eight nuclear ribosomal units on different chromosomes, which are assumed to evolve independently according to a birth-and-death model, in which new variants originate by duplication and others are deleted throughout time. Moreover, distinct ribosomal units were shown to be expressed during different developmental stages in the vertebrate and mosquito hosts. Here, the 18S rDNA sequences of 32 species of avian haemosporidian parasites are reported and compared to those of simian and rodent Plasmodium species.MethodsAlmost the entire 18S rDNAs of avian haemosporidians belonging to the genera Plasmodium (7), Haemoproteus (9), and Leucocytozoon (16) were obtained by PCR, molecular cloning, and sequencing ten clones each. Phylogenetic trees were calculated and sequence patterns were analysed and compared to those of simian and rodent malaria species. A section of the mitochondrial CytB was also sequenced.ResultsSequence patterns in most avian Plasmodium species were similar to those in the mammalian parasites with most species featuring two distinct 18S rDNA sequence clusters. Distinct 18S variants were also found in Haemoproteus tartakovskyi and the three Leucocytozoon species, whereas the other species featured sets of similar haplotypes. The 18S rDNA GC-contents of the Leucocytozoon toddi complex and the subgenus Parahaemoproteus were extremely high with 49.3% and 44.9%, respectively. The 18S sequences of several species from all three genera showed chimeric features, thus indicating recombination.ConclusionGene duplication events leading to two diverged main sequence clusters happened independently in at least six out of seven avian Plasmodium species, thus supporting evolution according to a birth-and-death model like proposed for the ribosomal units of simian and rodent Plasmodium species. Patterns were similar in the 18S rDNAs of the Leucocytozoon toddi complex and Haemoproteus tartakovskyi. However, the 18S rDNAs of the other species seem to evolve in concerted fashion like in most eukaryotes, but the presence of chimeric variants indicates that the ribosomal units rather evolve in a semi-concerted manner. The new data may provide a basis for studies testing whether differential expression of distinct 18S rDNA also occurs in avian Plasmodium species and related haemosporidian parasites.

Parasitaemia data and molecular characterization of Haemoproteus catharti from New World vultures (Cathartidae) reveals a novel clade of Haemosporida

BackgroundNew World vultures (Cathartiformes: Cathartidae) are obligate scavengers comprised of seven species in five genera throughout the Americas. Of these, turkey vultures (Cathartes aura) and black vultures (Coragyps atratus) are the most widespread and, although ecologically similar, have evolved differences in morphology, physiology, and behaviour. Three species of haemosporidians have been reported in New World vultures to date: Haemoproteus catharti, Leucocytozoon toddi and Plasmodium elongatum, although few studies have investigated haemosporidian parasites in this important group of species. In this study, morphological and molecular methods were used to investigate the epidemiology and molecular biology of haemosporidian parasites of New World vultures in North America.MethodsBlood and/or tissue samples were obtained from 162 turkey vultures and 95 black vultures in six states of the USA. Parasites were identified based on their morphology in blood smears, and sequences of the mitochondrial cytochrome b and nuclear adenylosuccinate lyase genes were obtained for molecular characterization.ResultsNo parasites were detected in black vultures, whereas 24% of turkey vultures across all sampling locations were positive for H. catharti by blood smear analysis and/or PCR testing. The phylogenetic analysis of cytochrome b gene sequences revealed that H. catharti is closely related to MYCAMH1, a yet unidentified haemosporidian from wood storks (Mycteria americana) in southeastern USA and northern Brazil. Haemoproteus catharti and MYCAMH1 represent a clade that is unmistakably separate from all other Haemoproteus spp., being most closely related to Haemocystidium spp. from reptiles and to Plasmodium spp. from birds and reptiles.ConclusionsHaemoproteus catharti is a widely-distributed parasite of turkey vultures in North America that is evolutionarily distinct from other haemosporidian parasites. These results reveal that the genetic diversity and evolutionary relationships of avian haemosporidians are still being uncovered, and future studies combining a comprehensive evaluation of morphological and life cycle characteristics with the analysis of multiple nuclear and mitochondrial genes will be useful to redefine the genus boundaries of these parasites and to re-evaluate the relationships amongst haemosporidians of birds, reptiles and mammals.

Blood parasites in northern goshawk (Accipiter gentilis) with an emphasis to Leucocytozoon toddi.

Haemosporidians and trypanosomes of the northern goshawk (Accipiter gentilis) population in the Czech Republic were studied by morphological and molecular methods. Despite the wide distribution of these medium-large birds of prey, virtually nothing is known about their blood parasites. During a 5-year period, altogether 88 nestlings and 15 adults were screened for haemosporidians and trypanosomes by microscopic examination of blood smears and by nested PCR. Both methods revealed consistently higher prevalence of blood protists in adults, Leucocytozoon (80.0 % in adults vs. 13.6 % in nestlings), Haemoproteus (60.0 vs. 2.3 %), Plasmodium (6.7 vs. 0 %), and Trypanosoma (60.0 vs. 2.3 %). Altogether, five haemosporidian lineages were detected by cytochrome b sequencing. Two broadly distributed and host nonspecific lineages, Plasmodium (TURDUS1) and Leucocytozoon (BT2), were detected only sporadically, while three newly described northern goshawk host-specific Leucocytozoon lineages (ACGE01-03) represent the absolute majority of the haemosporidians identified by molecular methods. Our findings support evidences that in falconiform birds the Leucocytozoon toddi group is formed by several host-specific clusters, with Leucocytozoon buteonis in buzzards and Leucocytozoon mathisi in hawks. Between-year comparisons revealed that the infection status of adults remained predominantly unchanged and individuals stayed uninfected or possessed the same parasite lineages; however, two gains and one loss of blood parasite taxa were also recorded.

Differential Haemoparasite Intensity between Black Sparrowhawk (Accipiter melanoleucus) Morphs Suggests an Adaptive Function for Polymorphism

Recent research suggests that genes coding for melanin based colouration may have pleiotropic properties, in particular conveying raised immune function. Thus adaptive function of polymorphism may be associated with parasite resistance. The black sparrowhawk Accipiter melanoleucus is a polymorphic raptor with two morphs. Over most of its range the light morph is commonest, however within the recently colonised Western Cape of South Africa the dark morph predominates. The species breeds in winter throughout South Africa, however unlike in the rest of the species' South African range, the Western Cape experiences a winter rainfall regime, where arthropod vectors which transmit haematozoan parasites may be more abundant. We hypothesise that the higher frequency of dark morph birds in this region may be due to their improved parasite resistance, which enables them to cope with higher parasite pressure. If so, we predict that dark morph black sparrowhawks would have lower parasite burdens than light morph birds. Within our population the prevalence of the two most common haematozoan parasites was high, with 72% of adults infected with Haemoproteus nisi and 59% of adults infected with Leucocytozoon toddi. We found no difference in prevalence for either parasite between adult morphs, or between chicks of different parental morphs. However, within adults infected with H. nisi, infection intensity was significantly higher in light morphs than dark morphs. This suggests that dark morphs have lower parasite loads than light morphs due to resistance rather than morph-specific habitat exploitation. Greater resistance to Haemoproteus parasites may therefore be one of the mechanisms through which dark morph black sparrowhawks have a selective advantage in this region and may explain why they are most common in our study area. In other regions, the cost to benefit ratio may be in favour of the light morph, where parasites are less abundant or virulent.

Identification of Leucocytozoon toddi Group (Haemosporida: Leucocytozoidae), with Remarks on the Species Taxonomy of Leucocytozoids

The current taxonomy of leucocytozoids (Haemosporida, Leucocytozoidae) is based on the morphology of blood stages of the parasites and on limited information about their specificity. Recent molecular studies have revealed a remarkable genetic diversity of leucocytozoids, indicating that their taxonomic diversity may be greater than in the current classifications. We addressed this issue using morphological data and phylogenetic analysis of the cytochrome b gene of 14 positively identified species of avian haemosporidians. Based on the current taxonomy, Leucocytozoon toddi is the sole species of leucocytozoids parasitizing falconiform birds. However, several distinct haplotypes have been revealed in falconiform birds, suggesting that L. toddi might be a group of cryptic species. We investigated the morphology of blood stages of leucocytozoids of 2 haplotypes (2 lineages from Accipiter spp. and 3 lineages from Buteo spp.) and concluded that these parasites can be readily distinguished due to length of the cytoplasmic processes of their host cells; therefore, they do represent distinct morphospecies. Morphology of the cytoplasmic processes of host cells warrants more attention in the taxonomy of Leucocytozoon species. Leucocytozoon toddi indeed is a species group that currently includes Leucocytozoon mathisi, Leucocytozoon buteonis, and L. toddi; additional morphospecies can be added to this group in the future. It is probable that some other morphospecies of Leucocytozoon also might be groups of closely related species.

Parasite Infections in Nestling Red-Shouldered Hawks (Buteo lineatus) in Northeast Wisconsin

Red-shouldered hawks (Buteo lineatus) are threatened in Wisconsin and long-term data suggest that nest productivity is low in the state for unknown reasons. Our objective was to determine whether red-shouldered hawks in northeast Wisconsin were infected with parasites that could contribute to low nest productivity. We examined nestlings for the presence of Trichomonas gallinae, Protocalliphora avium, and blood parasites in June 2006 and 2007. We did not detect T. gallinae in throat swabs taken from 24 nestlings in 2007. Ear canals of nestlings were parasitized by P. avium larvae in 10 of 11 (91%) nests and in 22 of 24 (92%) nestlings. Larvae were found in higher intensity in 1 ear relative to the other. Leucocytozoon toddi was present in 90.5% (38/42) of the nestlings. At least 1 bird in each nest was infected. Intensity of L. toddi averaged 48.6 +/- 58.3 infected cells per 2,000 erythrocytes (2.4 +/- 2.9%). No other blood parasites were identified.

Identification of different protozoa species from a common buzzard (Buteo buteo)

An adult, female common buzzard (Buteo buteo) with paraplegia due to shooting wound on the sacral region was diagnosed with Leucocytozoon toddi, Haemoproteus elani, and Histomonas meleagridis. This is the first report of simultaneous naturally occurring Leucocytozoon toddi, Haemoproteus elani, and Histomonas meleagridis identification in a buzzard.

Fitness in common buzzards at the cross‐point of opposite melanin–parasite interactions

1 Melanin is one of the major pigments of vertebrates and has many suggested functions. Although it is supposed to have an antipathogenic effect, its relationship to infection with ecto- and endoparasites largely remains to be examined. 2 The common buzzard Buteo buteo occurs in three eumelanin morphs which differ in their lifetime reproductive success. We examined the distribution of the blood-sucking ectoparasite Carnus haemapterus and the blood parasite Leucocytozoon toddi among buzzard nestlings and related parasite infection to the morph of the host and its parents. We controlled the effect of melanin morph on parasites for the potentially confounding total leukocyte numbers, heterophil : lymphocyte ratio (H : L ratio), age, sex, hierarchical rank within the brood and annual food availability. 3 Blood parasite prevalence was lower in offspring of intermediately coloured males. This pattern was apparent during high and low food availability, and although this result did not remain under intermediate vole densities, it could contribute to observed fitness differences in male buzzards. In contrast, carnid fly score increased with darkness of the host plumage. However, among chicks infected with the blood parasite, Leucocytozoon infection intensity decreased with plumage darkness. 4 The two parasite species may exert selection pressures in opposite directions on melanism of their host. Therefore, buzzards with intermediate amounts of melanin may prosper as they are sufficiently protected against endoparasites, but not too attractive for ectoparasites. Parasites could help explain the persistence of colour polymorphism in their buzzard host.

Prevalence of Hematozoa in Falcons in the United Arab Emirates With Respect to the Origin of Falcon Hosts

To determine the prevalence of blood parasites with regard to country of origin in a population of falcons kept in the United Arab Emirates (UAE), 432 falcons of 3 different species and 2 hybrid species originating from Asia, Europe, and the United States were examined. Birds were divided into 2 groups. Group 1 comprised 323 birds examined immediately after arrival in the UAE. Blood parasites were detected in 6.8% of birds. Group 2 comprised 109 birds kept longer than 5 months in the UAE; of these, 15.6% were positive for blood parasites. No hybrids (captive bred birds from the United States or Germany) were positive in group 1, whereas 18.2% of the gyrfalcon/saker and 5.9% of the gyrfalcon/peregrine hybrids in group 2 were infected with blood parasites. Wild-caught birds from Asia were positive in both groups. In total, 39 (9%) of the 432 falcons examined were infected with blood parasites. The blood parasites detected were identified as Haemoproteus tinnunculi (5.3%), Haemoproteus brachiatus (0.9%), Leucocytozoon toddi (0.9%), and rickettsia-like parasites (1.9%). This study appears to be the first to investigate the prevalence of blood parasites within the UAE with regard to the origin of the birds. Additionally, it is the first report of H brachiatus in a saker falcon (Falco cherrug). No correlations were found between infection with a blood parasite and clinical disease in the birds in this study.

Attraction between sexes: male–female gametocyte behaviour within a Leucocytozoon toddi (Haemosporida)

Understanding the breeding systems of Plasmodium, and the closely related Haemoproteus and Leucocytozoon (Apicomplexa: Haemosporida), is fundamental to virulence and transmission research. We report an unusual binding behaviour between gametocytes of Leucocytozoon toddi. This aggregative behaviour was notably characterised by a disparity in the likelihood of clustering by female and male gametocytes. Thus, indicating a possible difference in the 'stickiness' of gametocytes per sex. Overall, 12% of gametocytes in this high-parasitaemia infection (0.269 gametocytes per 100 red blood cells (RBCs)) were incorporated into aggregations involving substantial contact. The gametocyte sexual combinations within aggregations varied significantly from expected according to the background 0.49 sex ratio within this sample, with female-female contacts occurring more and male-male contacts occurring less frequently than expected. A second L. toddi (identical for 709 bp of the cyt b mitochondrial gene) with lower parasitemia (0.035 gametocytes per 100 RBCs) showed no significant binding. Interestingly, the ratios of male gametocytes in both of these parasites were greater than expected under sex-ratio theory and similar to the 50% observed in species with syzygy breeding strategies. We discuss the ramifications of this observation in terms of sex-ratio theory and breeding strategies and provide speculative explanations for this unusual gametocyte behaviour.

EVIDENCE FOR CRYPTIC SPECIATION OF LEUCOCYTOZOON SPP. (HAEMOSPORIDA, LEUCOCYTOZOIDAE) IN DIURNAL RAPTORS

Species of Leucocytozoon (Haemosporida, Leucocytozoidae) traditionally have been described based on morphological characters of their blood stages and host cells, with limited information on their avian host specificity. Based on the current taxonomy, Leucocytozoon toddi is the sole valid species of leucocytozoids parasitizing falconiform birds. Using a nested polymerase chain reaction protocol, we determined the prevalence of Leucocytozoon infection in 5 species of diurnal raptors from California. Of 591 birds tested, 177 (29.9%) were infected with Leucocytozoon toddi. Subsequent phylogenetic analysis of the cytochrome b gene revealed that distinct haplotypes are present in hawks of these genera. Haplotypes present in Buteo spp. are not found in Accipiter spp., and there is a 10.9% sequence divergence between the 2 lineage clades. In addition, Leucocytozoon sp. from Accipiter spp. from Europe group more closely with parasites found in Accipiter spp. from California than the same California Accipiter species do with their sympatric Buteo spp. Similarly, a Leucocytozoon haplotype from a Common Buzzard (Buteo buteo) from Kazakhstan forms a monophyletic lineage with a parasite from B. jamaicensis from California. These results suggest that Leucocytozoon toddi is most likely a group of cryptic species, with 1 species infecting Buteo spp. and 1 or more species, or subspecies, infecting Accipiter spp.

Migratory Movements of Sharp-Shinned Hawks (Accipiter Striatus) Captured in New Mexico in Relation to Prevalence, Intensity, and Biogeography of Avian Hematozoa

Abstract Previous interspecific studies have shown that migratory birds have a higher prevalence of blood parasites than nonmigratory birds. It is thought that birds that move greater distances are exposed to a larger parasite fauna, because of uneven distribution of vectors that carry such parasites. Current hypotheses also suggest that the stress of migration may allow parasites to persist, by weakening the immune system and allowing latent infections to recur. We captured migrating hatching-year Sharp-shinned Hawks (Accipiter striatus) in New Mexico and estimated natal latitudes of each individual by analyzing stable-hydrogen isotope ratios of feathers. That enabled us to estimate distances traveled up to point of capture. We also collected blood to quantify hematozoan infection prevalence and intensity. We related distance traveled to prevalence and intensity of hematozoan infections. Contrary to previous hypotheses, our results show no relationship between distance traveled by migrants and prevalence and intensity of hematozoan infections. Of 75 individuals examined, 24% were infected with Leucocytozoon toddi, 37% with Haemoproteus elani, and 5% with H. janovyi. To our knowledge, this is the first documented occurrence of H. janovyi in North America and in Sharp-shinned Hawks. Our stable-hydrogen isotope analyses indicated that H. janovyi was detected only in birds that originated in southwestern North America, which may be of significance in regard to biogeography of that parasite species.

Intracellular Hematozoa of Raptors: A Review and Update

The intracellular hematozoa of vertebrates are apicomplexan parasites with a life cycle consisting of 3 major phases: schizogony (asexual), gametogony (sexual), and sporogony (asexual). Most members have heteroxenous life cycles, wherein gametogony and sporogony occur in an arthropod vector and schizogony occurs in the vertebrate host. Leucocytozoon toddi occurs in Falconiformes and Leucocytozoon ziemanni in Strigiformes. Considered nonpathogenic in adult raptors, Leucocytozoon can cause mortality in nestlings. Haemoproteus is generally considered nonpathogenic in raptors; however, there are recent reports of fatalities in owls. Plasmodium is the true malarial parasite of birds and mammals. One species, Plasmodium relictum, is considered pathogenic for raptors. Atoxoplasma (previously Lankesterella) is an avian coccidian with both blood and intestinal stages. Babesia has been reported in raptors and might cause anemia and blindness in young falcons. In this article, advances in hematozoon diagnosis, treatment, and prevention are discussed. Although some hematozoa of raptors are considered nonpathogenic, high parasitemias in peripheral blood could indicate an underlying disease process.

Leucocytozoon toddi and Haemoproteus tinnunculi (Protozoa: Haemosporina) in the Chimango caracara (Milvago chimango) in southern Chile.

Two species of blood protozoans were identified from blood smears collected from 15 specimens of the Chimango caracara (Milvago chimango) on Isla Grande de Chiloé in southern Chile. These included Leucocytozoon toddi in 13 birds, including all 5 of the 4-6 week old nestlings examined, and 8 of the subadults or adults. One of the nestlings also had a dual infection of L. toddi and Haemoproteus tinnunculi. These are the first reports of blood parasites from M. chimango.

Leucocytozoonosis in nestling bald eagles in Michigan and Minnesota.

Thirteen of 21 nestling bald eagles (Haliaeetus leucocephalus) examined for blood parasites in Michigan and Minnesota (USA) during June and July 1997 had patent infections of Leucocytozoon toddi. No other parasites were seen. The degree of parasitemia was light and varied from 1 to 2 on the Ashford Scale. Several of the infected nestlings appeared to have elevated levels of heterophils in their peripheral circulating blood. One of the infected nestlings also showed signs of severe anemia. We believe this is the first report of L. toddi in the bald eagle.

HEMOGRAMS AND HEMATOZOA OF SHARP-SHINNED (ACCIPITER STRIATUS) AND COOPER'S HAWKS (ACCIPITER COOPERII) CAPTURED DURING SPRING MIGRATION IN NORTHERN NEW YORK

Hemograms were determined for 26 Cooper's (Accipiter cooperii) and 55 sharp-shinned hawks (Accipiter striatus) captured during spring migration (27 March to 12 May 1987) on the south shore of Lake Ontario, New York (USA). No significant differences were noted in packed cell volume and estimated total solids between the species. However, Cooper's hawks had significantly higher total white blood cells counts and higher concentrations of heterophils, monocytes, and eosinophils. Proportionally, lymphocytes made up a smaller percentage of the differential count in the Cooper's hawk. Eosinophil concentrations and percentages of the differential count were significantly higher in the females of both species. Both species had a high prevalence of Leucocytozoon toddi and Haemoproteus spp. infection. Haemoproteus nisi and H. elani were identified in both hawks. Trypanosoma avium was identified in a single Cooper's hawk and Plasmodium circumflexum was identified in a sharp-shinned hawk. Prevalence of Leucocytozoon toddi and Haemoproteus spp. infections were significantly higher in the birds caught late in the spring as compared to those caught earlier in the spring; this was evidence for a spring recrudescence of patent parasite infections.

THE LEUCOCYTOZOIDAE OF SOUTH AFRICAN BIRDS: FALCONIFORMES AND STRIGIFORMES

Summary Bennett, G. F., Earle, R. A. & Peirce, M. A. 1993. The Leucocytozoidae of South African birds: The Falconiformes and Strigiformes. Ostrich 64: 67–72. The leucocytozoids of the raptors are reviewed and Leucocytozoon toddi of the Falconiformes and Leucocytozoon ziemanni of the Strigiformes are re-described; Leucocytozoon beaurepairei of the Sagittaridae is resurrected from synonymy.

Haematozoa of raptors and other birds from Britain, Spain and the United Arab emirates

In Britain, 20.3% of raptors examined were infected with haematozoa and in Spain 14.2%. Of the birds from the United Arab Emirates 24.1% were found to be infected. Haemoproteus tinnunculi, H. nisi, Leucocytozoon toddi, L. ziemanni and Trypanosoma avium were identified from raptors and H. telfordi from a Houbara Bustard.

Haematozoa of British birds. VII. Haematozoa of raptors in Scotland with a description ofHaemoproteus nisisp. nov. from the sparrowhawk (Accipiter nisus)

Summary A study of haematozoa in free-living raptors in southern Scotland showed that in Accipiter nisus there was a very high infection rate with Leucocytozoon toddi. Nestlings showed patent parasitaemias, often very high, as early as 14 days of age. Most patent infections in adult birds were considered to be due to relapses. A description is given of Haemoproteus nisi sp. nov. which was observed in 32 birds; H. figueiredoi was observed in one bird. Most haemoproteid infections were observed in adult birds, especially breeding females at the nest. Trypanosoma corvi was found in A. nisus and B. buteo, mostly in nestlings. Two species of hippoboscids, Ornithomyia avicularia and O. chloropus, were collected and may be involved in the transmission of H. nisi and T. corvi. Although there was no direct evidence of pathogenicity with any of the parasites observed it is suggested that L. toddi may be a contributing factor in the mortality of chicks in some areas.