Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

Blood parasites (Kinetoplastida: Trypanosomatidae)

infecting birds in the Brazilian Amazon

Pedro Ferreira França1; https://orcid.org/0000-0002-7234-8765

Darlison Chagas-de-Souza2; https://orcid.org/0000-0002-7610-9665

Tássio Alves Coêlho2; https://orcid.org/0000-0002-0264-4526

Edson Varga Lopes1,3; https://orcid.org/0000-0002-8278-5141

Lincoln Lima Corrêa4*; https://orcid.org/0000-0002-6453-4824

1. Programa de Pós-graduação em Biodiversidade (PPGBEES), Universidade Federal do Oeste do Pará, 68015-110,

Santarém, Pará, Brazil; francaornito@hotmail.com, papaformiga@yahoo.com.br

2. Laboratório de Estudos Morfofisiológicos e Parasitários, Universidade Federal do Amapá, 68903-419 Macapá, AP,

Brazil; darlisondcs@hotmail.com, coelho.tassio@gmail.com

3. Laboratório de Ecologia e Conservação, Instituto de Biodiversidade e Florestas (IBEF), Universidade Federal do Oeste

do Pará, 68015-110, Santarém, Pará, Brazil.

4. Instituto de Ciências e Tecnologia das Águas (ICTA), Universidade Federal do Oeste do Pará, 68015-110, Santarém,

Pará, Brazil; lincorre@gmail.com (*Correspondence)

Received 17-IV-2023. Corrected 04-VII-2023. Accepted 26-IX-2023.

ABSTRACT

Introduction: Trypanosomes are hemoparasites that can be observed circulating in the peripheral blood of birds.

Parasitological studies in birds in their natural environment are neglected, but are important for research relat-

ing to transmission, maintenance of the biological cycle, and abundance, among other parasitological aspects.

Objective: To describe infections by Trypanosoma sp. in birds in the Brazilian Amazon, as well as the prevalence,

morphological and morphometric characteristics of this hemoparasite.

Methods: In the Tapajós National Forest, we captured a total of 125 birds, mostly from the order Passeriformes.

We obtained blood samples from the ulnar vein using sterile insulin needles, and aliquots of blood using a

microhematocrit capillary tube. We made blood smears in triplicate and stained with the Giemsa method. We

viewd the morphotypes of the Trypanosoma sp. under the light microscope with objective lenses of 40 X and

100 X. To determine the morphometric characteristics of Trypanosomatidae, we used the Zen Blue Edition 2

software package.

Results: We observed the presence of hemoparasites in the trypomastigote form in specimens of Thamnophilidae,

Dendrocolaptidae and Conopophagidae, with low prevalence. Only one morphotype of Trypanosoma sp. was

detected and measurement.

Conclusions: We report the infection by Trypanosoma sp. in species of ecological importance, such as Phlegopsis

nigromaculata, endangered in Brazil. The morphology and morphometry of the morphotype found could con-

tribute to more detailed descriptions of these hemoparasites.

Key words: hemoparasites; morphology; Trypanosoma; Brazil.

https://doi.org/10.15517/rev.biol.trop..v71i1.54843

VERTEBRATE BIOLOGY

2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

INTRODUCTION

A large number of parasites can be observed

in the blood of birds (White et al., 1978). These

microscopic organisms have a cosmopolitan

distribution, and have been described in sev-

eral groups of bird hosts in practically every

geographic region of the world (Lisbôa et al.,

2008). Although there are few records of health

changes resulting from trypanosome infection

in birds, there is similarity with the manifes-

tation in mammals, and changes in cardiac

tissue, liver, and spleen have been observed

(Mungomba et al., 1989). In addition, parasitic

infections in birds affect the mechanisms of

sexual selection, migration, reproduction, com-

petition and, in more severe cases, result in the

extinction of certain local bird species (Altizer

et al., 2000; McCallum & Dobson, 1995).

Trypanosomes are flagellated protozoa and

it is the most abundant and most important

genus among kinetoplastids. Trypanosomes are

extensively studied because they cause serious

diseases of humans (Chagas disease, sleeping

sickness) and domestic animals (Taylor et al.,

2007). In contrast to their mammalian relatives,

avian trypanosomes are in most cases harmless

to their hosts and they remain understudied

although they are not less interesting (Baker,

1976). The transmission in birds can occur

through a variety of vectors, such as mites, lice,

culicids, and simuliids (Molyneux, 1977; Svo-

bodová et al., 2017; Votýpka et al., 2012).

Although experimental infections involv-

ing vectors and birds have been performed

(Bennett, 1961; David & Nair, 1955; Votýpka et

al., 2012), aspects of avian trypanosome trans-

mission are poorly understood (Votýpka et al.,

2012). However, some of them are known to

be transmitted by ingestion of infected vectors

or by contamination of the host’s worn skin

or conjunctiva with parasites present in the

vector’s feces (the hypphoboscid fly Ornitho-

myia avicularia and the black fly Eusimulium

securiforme) (Desser et al., 1975; Mungomba

et al., 1989; Svobodová et al., 2017; Votýpka &

Svobodová, 2004; Votýpka et al., 2012).

Although some species of the genus Try-

panosoma are etiological agents of diseases

that represent a public health concern, the

vast majority of trypanosomes species remain

neglected by research. There is a lack of

RESUMEN

Parásitos sanguíneos (Kinetoplastida: Trypanosomatidae) que infectan aves en la Amazonía brasileña

Introducción: Los tripanosomas son hemoparásitos que pueden observarse circulando en la sangre periférica

de las aves. Los estudios parasitológicos en aves en el medio natural son escasos, pero son importantes para la

investigación relacionada con la transmisión, el mantenimiento del ciclo biológico y la abundancia, entre otros

aspectos parasitológicos.

Objetivo: Describir infecciones por Trypanosoma sp. en aves de la Amazonia brasileña, así como la prevalencia,

características morfológicas y morfométricas de este hemoparásito.

Métodos: En la Floresta Nacional de Tapajós, capturamos un total de 125 aves, la mayoría del orden Passeriformes.

Obtuvimos muestras de sangre por punción de la vena cubital del ala con agujas estériles de insulina. Con un tubo

capilar microhematocrito, obtuvimos alícuotas de sangre. Realizamos frotis de sangre por triplicado y teñimos

con el método de Giemsa. Visualizamos los morfotipos de Trypanosoma sp. al microscopio óptico con lentes

objetivos de 40 X y 100 X. Para determinar las características morfométricas de Trypanosomatidae, usamos el

paquete informático Zen Blue Edition 2.

Resultados: Observamos la presencia de hemoparásitos en la forma tripomastigote en ejemplares de la familia de

aves Thamnophilidae, Dendrocolaptidae y Conopophagidae, con baja prevalencia. Solo detectamos un morfotipo

de Trypanosoma sp.

Conclusión: Reportamos la infección por Trypanosoma sp. en especies de importancia ecológica, como Phlegopsis

nigromaculata en peligro de extinción en Brasil. La morfología y morfometría del morfotipo encontrado puede

contribuir con descripciones más detalladas de estos hemoparásitos.

Palabras clave: hemoparásitos; morfología; Trypanosoma; Brazil.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

information about aspects of the biological

cycle, hosts and prevalence, morphology, and

morphometry data of bird trypanosomes,

with the Amazon region being the least stud-

ied environment in this respect (Baker, 1976;

Valkiūnas et al., 2011).

In recent years, in Brazil and its different

biomes, including the Amazon, there has been

an increase in studies involving birds and hae-

mosporidians (Anjos et al., 2021; De La Torre

et al., 2021; Fecchio et al., 2007; Fecchio et al.,

2017; Fecchio et al., 2018; Fecchio et al., 2019;

Fecchio, de Faria et al., 2021; Fecchio, Lima et

al., 2021; Fecchio et al., 2022; Ferreira-Junior et

al., 2017; Ferreira-Junior et al., 2018; Ribeiro et

al., 2004; Roos et al., 2015; Sebaio et al., 2012).

However, the focus of these studies, although

very important, has been on the parasite-host

relationships, the life cycles, the vectors and the

consequences of these relationships between

birds and haemosporidians. Nevertheless, stud-

ies on avian trypanosomes remain scarce, espe-

cially when focusing on the Amazon region.

In terms of both area and diversity, the

Amazon region is the most important habitat

for Neotropical birds. About 800 species of

birds have been recorded in the Amazonia

biome, of which about 265 are endemic to

the region (Nores, 2000). The most important

families are Psittacidae, Trochilidae, Rampha-

stidae, Cracidae, Formicariidae, Tyrannidae,

Furnariidae, Cotingidae, Pipridae and Den-

drocolaptidae (Nores, 2000). Furthermore, the

Amazon Basin is highly heterogeneous, with

different phytophysiognomies providing a vari-

ety of habitats (Silva et al., 2005).

Studies of vertebrate biogeography have

shown that the distribution of many species in

the Amazon Basin is not continuous, suggest-

ing that similar distribution patterns of these

vertebrates are from centers of endemism (Silva

& Oren, 1996). Thus, it has been proposed that

there are seven recognized areas of endemism

in the Amazon, including the Western and

Southwestern regions of the State of Pará, in

addition to the Belém area of endemism in the

capital region of Pará, Brazil (Cracraft, 1985;

Silva & Oren, 1996).

In view of the importance of this biome

for the diversity of bird species, it is clear that

research on hemoparasites is of great impor-

tance for the region and can provide relevant

information on the different groups of hemo-

parasites to be studied, as well as the discov-

ery of new parasite species and their vectors.

The present study aims to record infection by

Trypanosoma sp. in wild birds from a locality

in the Brazilian Amazon, in addition to pro-

viding information on the infection intensity,

prevalence and morphometric characteristics

of trypanosomes.

MATERIALS AND METHODS

Location of bird collection: The present

study was carried out in the Floresta Nacional

do Tapajós (FLONA do Tapajós), a sustainable

use Conservation Unit in the Eastern Amazon,

in the West of the state of Pará (3°31’1” S &

55°4’23” W), the area has an elevation range of

~55-220 m.a.s.l. The reserve is 527 319 hectares

in size, and is delineated to the West by the

Tapajós River, to the East by the Santarém-

Cuiabá highway (BR-163), to the North by the

rural zone of the Belterra municipality and to

the South by the Cupari River. In the Tapajós

National Forest, there are two forest typologies:

i) Floresta Ombrófila Densa Aluvial, which are

those located on the banks of the Tapajós River

and its tributaries and streams within the Tapa-

jós National Forest; and ii) Floresta Ombrófila

Densa de terras baixas, where there is a large

occurrence of species of the genus Alchornea,

Handroanthus and Ficus, especially Ficus cestri-

folia Schott ex Spreng. and the species Tapirira

guianensis and Calophyllum brasiliensis (Carv-

alho et al., 2021).

Bird capture: The birds were captured

during June and August 2018 using mist nets

10 m long by 2.5 m high, with a 16 mm mesh.

Ten nets were installed in each of the 16 plots

sampled, which were 1 km apart and at least

500 meters from the edge of the forest. The

nets were set in each plot for two consecutive

days during the morning period. The sampling

4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

effort was 120 h/net per plot, totaling 1 920

h/net, with inspections carried out at regular

intervals of 30 min. The individuals captured

were identified to the species level and follow-

ing the nomenclature and taxonomy established

in accordance with the Brazilian Committee of

Ornithological Records. The specimens were

identified with metal rings provided by the

National Center for the Research and Con-

servation of Wild Birds (CEMAVE), in order

to prevent the same bird being sampled more

than once.

Blood collection and methods of detec-

tion of hemoparasites and morphometry of

Trypanossoma sp.: Sterile insulin needles were

used to obtain blood samples by puncture of

the ulnar (wing) vein. A heparinized micro-

hematocrit capillary tube was then used to

collect aliquots of blood. A blood sample was

taken from the tube and used to prepare blood

smears in triplicate. The smears were air dried.

The slides were fixed in methanol and stained

with Giemsa stain (RenyLab® Brazil) accord-

ing to the Romanowsky principle. The mor-

photypes of trypanosomatidae were evaluated.

Light microscopy was used to study hemopara-

sites. Parasites were photographed in a Zeiss

Axioplan light microscope with an Axiocam

ERc 5S camera.

Measurements were taken from Trypano-

soma sp., including total body length with

flagellum (TL), body length along the midline

(BL), body width at the center of the nucleus

(BW), free flagellum length (F), nucleus length

(NL), nucleus width in the central portion

(NW), distance from the center of the nucleus

to the anterior extremity (NA), distance from

the center of the nucleus to the posterior

extremity (NP), distance from the center of

the kinetoplast to the center of the nucle-

us (KN), kinetoplast length (KL), kinetoplast

width (KW) and distance from the center of

the kinetoplast to the posterior end (KP). The

Zen Blue Edition 2 software package was used

to determine the morphometric characteristics

of Trypanosomatidae (Baker, 1956; Baker, 1966;

Baker, 1976).

Statistical analysis: To determine the

intensity of infection (expressed in parasites/

ml), the direct method was used, based on the

methodology described by De Carli (2001).

This consists of counting all the parasites found

in 100 microscopic fields with a magnification

of 1 000X, recorded and calculated as follows:

100 microscopic fields is equivalent to 0.2 μl

of blood (infection intensity = (N°: number

of parasites × 5) × 1 000 = (parasites/ml). The

ecological terms used and the infection param-

eters of prevalence, mean abundance and mean

intensity with respectives confidence interval

(IC) 95 % were calculated following Bush et

al. (1997), using Quantitative Parasitology 3.0

software (Reiczigel & Rózsa, 2005).

To perform the morphometric measure-

ments, due to the low number of trypomastigotes

found, we used an N= 10 of trypomastigotes

found in the hosts. Thus, the mean values

of the morphological regions measured were

used to compare the morphometric similar-

ity described for bird trypanosomes using the

Bray-Curtis method, with the aid of the Past 4.0

statistical program (Hammer et al., 2001).

RESULTS

A total of 125 birds were captured, all of

which belonged to the Passeriformes order,

except Veniliornis affinis (Piciformes) (Table 1).

The analysis identified the presence of trypo-

mastigotes in three species of Thamnophilidae:

Myrmornis torquata (Fig. 1A), Phlegopsis nigro-

maculata (Fig. 1B) and Willisornis poecilinotus

(Fig. 1C); one species of Dendrocolaptidae:

Xiphorhynchus guttatus (Fig. 1D) and one spe-

cies of Conopophagidae: Conopophaga aurita

(Fig. 1E). The overall prevalence was 8.8 %

(IC= 0.044 to 0.152), mean abundance was 0.22

(IC= 0.10 to 0.48), mean intensity was 2.45 (IC=

1.55 to 4.36) and with an intensity of infection

of 27 500 parasites/ml. In this study we identi-

fied only one morphotype of Trypanosoma sp.

The prevalence per bird family sampled was

7.2 % for Thamnophilidae (n = 55), 2.0 % for

Dendrocolaptidae (N = 50) and 50.0 % for

Conopophagidae (N = 2).

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

Table 1

Bird species infected by Trypanosoma sp. and prevalence (per species infected) and the infection intensity (expressed in

parasites/mL of blood) in birds from the Tapajós National Forest, Pará, Brazil.

Hosts NInfected

Hosts

Infection intensity

Parasites / mL Prevalence

Picidae

Veniliornis affinis (Swainson, 1821) 1 0 - -

Thamnophilidae

Epinecrophylla leucophthalma (Pelzeln, 1868) 2 0 - -

Myrmotherula axillaris (Vieillot, 1817) 1 0 - -

Myrmotherula longipennis Pelzeln, 1868 1 0 - -

Myrmotherula menetriesii (d’Orbigny, 1837) 6 0 - -

Thamnomanes caesius (Temminck, 1820) 1 0 - -

Thamnophilus schistaceus d’Orbigny, 1835 6 0 - -

Sciaphylax hemimelaena (Sclater, 1857) 1 0 - -

Hypocnemis cantator (Boddaert, 1783) 1 0 - -

Willisornis poecilinotus (Cabanis, 1847) 6 1 20.000 0.167 (0.004 – 0.641)

Phlegopsis nigromaculata (d’Orbigny & Lafresnaye, 1837) 17 5 45.000 0.294 (0.123 – 0.544)

Rhegmatorhina gymnops Ridgway, 1888 5 0 - -

Myrmoborus myotherinus (Spix, 1825) 1 0 - -

Pyriglena leuconota (Spix, 1824) 1 0 - -

Myrmornis torquata (Boddaert, 1783) 6 3 60.000 0.500 (0.153 – 0.846)

Conopophagidae

Conopophaga aurita (Gmelin, 1789) 2 1 5.000 0.500 (0.254 – 0.974)

Formicariidae

Formicarius colma Boddaert, 1783 1 0 - -

Dendrocolaptidae

Dendrocincla fuliginosa (Vieillot, 1818) 23 0 - -

Glyphorynchus spirurus (Vieillot, 1819) 15 0 - -

Dendrocolaptes certhia (Boddaert, 1783) 1 0 - -

Dendrocolaptes hoffmannsi Hellmayr, 1909 2 0 - -

Dendrocolaptes picumnus Lichtenstein, 1820 1 0 - -

Hylexetastes perrotii (Lafresnaye, 1844) 1 0 - -

Xiphorhynchus spixii (Lesson, 1830) 2 0 - -

Xiphorhynchus guttatus (Lichtenstein, 1820) 4 1 5.000 0.250 (0.012 – 0.751)

Pipridae

Manacus manacus (Linnaeus, 1766) 1 0 - -

Onychorhynchidae

Onychorhynchus coronatus (Statius Muller, 1776) 5 0 - -

Tityridae

Schiffornis turdina (Wied, 1831) 1 0 - -

Platyrinchidae

Platyrinchus platyrhynchos (Gmelin, 1788) 2 0 - -

Passerellidae

Arremon taciturnus (Hermann, 1783) 4 0 - -

Cardinalidae

Habia rubica (Vieillot, 1817) 4 0 - -

Values inside the parenthesis represent 95 % confident intervals.

6Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

Morphotype characteristics of

Trypanosoma sp.

Taxonomic Summary

Hosts: Myrmornis torquata, Phlegopsis nigro-

maculata, Willisornis poecilinotus, Xiphorhyn-

chus guttatus, Conopophaga aurita.

Type locality: Tapajós National Forest, Munici-

pality of Belterra, Western Pará, Brazil.

Habitat: Blood.

The morphotype of Trypanosoma sp.

found (Fig. 2A, Fig. 2B) presents an elongated

cell body, predominantly “C” shaped, with two

flexures in the anterior region. Granulations

are present in the cytoplasm and the maximum

width of the body is equal to the maximum

width of the nucleus. The nucleus is spherical

to ovoid in shape with a karyosome present,

an ovoid kinetoplast projecting at the posterior

end. The distance between the kinetoplast and

the posterior end is evident. An undulating

membrane is present and easily recognized,

extending along the body with indistinguish-

able separation from the free flagellum. The

flagellum is about one third the size of the cell

body (Fig. 2C).

Fig. 1. Birds species parasitized by Trypanosoma sp. A.

Myrmornis torquata, B. Phlegopsis nigromaculata, C.

Willisornis poecilinotus, D. Xiphorhynchus guttatus, E.

Conopophaga aurita (Scale bar = 2cm).

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

The morphometrics described in the

present study were compared with other vali-

dated species of avian trypanosomes (Table 2).

According to the Bray-Curtis index, a simi-

larity morphometric of 96.15 % with Try-

panosoma ontarioensis was indicated (Fig. 3).

Despite the high morphological similarity,

species determination of the genus Trypano-

soma is impossible without the use of molecu-

lar methods. This is due to the plasticity of

the genus Trypanosoma in other vertebrates,

which does not allow species identification

based on morphology and morphometry

(Spodareva et al., 2018).

DISCUSSION

Various biological and ecological char-

acteristics of the host have been associated

with the prevalence of hemoparasites in birds.

In general, studies on the effects of avian

hemoparasites on the biological and ecological

characteristics of birds have focused on charac-

teristics such as sex, age, body mass, geographic

area, nest type, foraging layers, and feeding

habits. Little is known about the relationship

between feeding habits and hemoparasite sus-

ceptibility, although all positive birds in our

study were insectivorous.

Previous studies on blood-borne para-

sites in birds have shown that species of birds

that belong to insectivorous groups are more

susceptible to infection with Haemoproteus

and Plasmodium (Laurence et al., 2013). Thus,

hemoparasites of the genus Plasmodium sp.

the causative agent of avian malaria, have been

described as a potential cause of extinction

and population decline in many bird species,

reducing host fitness and in some cases causing

death (Cannell et al., 2013, Paxton et al., 2016).

Notably, there are no studies on the prevalence

Fig. 2. A. B. Trypomastigote forms of Trypanosoma sp. identified in the peripheral blood of birds from the Brazilian Amazon

(10µm bar), C. Schematic drawing of the morphotype of Trypanosoma sp. parasite of five species of birds from the Tapajós

National Forest, Brazil.

8Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

aspects of infection with these associations for

the avian trypanosome.

The differential susceptibility of bird

groups, in relation to hematozoans, may derive

from differences in the reproductive biology of

different species and habitat type, as well as fac-

tors such as small sample sizes (for some species

or families) and sampling in different seasons

of the year (Norris et al., 1994). In addition,

infection may depend on biological parameters

such as sex, age, plumage color and body condi-

tion, according to (Norris et al., 1994).

Bird trypanosomes have been described

in approximately 100 species based on mor-

phological features and host-specific factors,

but only a few morphological features have

been sufficiently described, because of inad-

equate illustrations and descriptions (Valkiūnas

et al., 2011). Although the morphometry of

the parasite may vary during the life cycle, its

morphological characteristics (body shape, free

flagellum, undulating membrane, kinetoplast

position and morphology) are well conserved

(Valkiūnas et al., 2011). We found the same

relationship when we performed similarity tests

with T. anguiformis and T. polygranularis that

had been characterized both morphologically

and molecularly by Valkiūnas et al. (2011).

Morphometrically, similarities were evi-

denced when we compared the morphotype

analyzed in the present study with T. ontarien-

sis. There was a similarity in the size of the cell

body, the distance from the posterior region

to the center of the nucleus, the distance from

the center of the nucleus to the anterior end,

and in the length of the free flagellum, with

these characteristics differentiating the mor-

phological types of T. avium, T. anguiformis,

Fig. 3. Dendrogram of morphometric similarity between Trypanosoma sp. and species of avian trypanosomes. (*Present

study).

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

T. polygranularis, T. irwini, T. naviformis, T.

paddae and T. corvi. Despite the close mor-

phometric similarity, it is not possible to con-

sider identification at the species level only

using the morphometric technique, due to the

notable plasticity of Trypanosoma spp. (Porn-

panom et al., 2019; Spodareva et al., 2018;

Valkiūnas et al., 2003).

The present study corroborates the find-

ings of Woo and Bartlett (1982), in which there

is no parasitic specificity for T. ontariensis, with

infection being observed in five different spe-

cies of hosts. According to Woo and Bartlett

(1982), T. ontariensis biologically resembles

T. corvi and T. avium, and can be transmitted

experimentally to a wide variety of birds, with

low parasitemia being observed in all experi-

mental infections.

The morphometry in the present study was

significant when compared to that of T. avium

and T. corvi. According to (Votýpka et al., 2004;

Votýpka et al., 2012) the species T. corvi and

T. avium belong to the “avium” group where

the large straited trypanosomes of birds are

grouped. These morphological types present

similar forms, described in different hosts in

the New and Old Worlds. Studies carried out by

(Mungomba et al., 1989) stated that the repre-

sentatives of the “avium” group suggest a com-

plex group of species, with robustness in the cell

body and free flagellum, findings corroborated

by the comparison with the morphotype found

in the present study.

Experimental studies of the trypanosome

life cycle of birds show that many Trypanosoma

species can be easily distinguished using mor-

phometry alone during co-infections (Moly-

neux, 1977; Mungomba et al., 1989). In relation

to the variability of morphological forms (par-

ticularly during development in vectors and

in the initial morphogenesis of the metacyclic

forms in birds), the hematozoic trypomastigote

form is relatively fully developed, with a mor-

phology with highly conserved characteristics,

Table 2

Morphometric data of trypomastigote forms and of various species of Trypanosoma spp. parasites of birds

Measurements (µm)

Trypanosoma sp.*

T. avium (A) (Baker, 1956)

T.avium (B) (Baker, 1956)

T. avium (Grewal, 1963)

T. anguiformis

(Valkiūnas et al., 2011)

T. everetti (Molyneux, 1973)

T. polygranularis

(Valkiūnas et al., 2011)

T. irwini

(McInnes et al., 2009)

T. navifor mis

(Sehgal et al., 2015)

T. paddae

(Woo & Bartlett, 1982)

T. ontarioensis

(Woo & Bartlett, 1982)

T. cf. corvi (Slender form)

(Pornpanom et al., 2019)

T. cf. corvi (Intermediate form)

(Pornpanom et al., 2019)

T. cf. corvi (Broad form)

(Pornpanom et al., 2019)

T. avium

(Pornpanom et al., 2019)

TL 25.6 56 51.1 43.5 32.9 22.3 30.6 40.9 22.5 42 26.4 62.8 62.4 67.1 49.4

BL 17.4 52.1 43.7 40.6 28.6 17.4 20.6 30.6 22.5 36.3 18 52.4 50.7 56.3 40.5

KP 0.4 – – 10.7 2.3 0.9 1.8 3.6 1.9 8 1.4 6.8 7.3 9.1 6.3

NP 8.9 24.9 20 19.5 16.2 – 13.3 0 11.2 19 8.3 21 20.8 24.5 17.2

NA 8.5 – – – 11.8 7.7 13.3 11.9 11.1 17.3 9.6 27.2 29.2 30.3 20.8

KN 8.4 – – – 14.1 7.9 11.6 10.3 9.2 11 6.6 12.6 13.1 13.6 9.7

FF 8.3 6.2 7.4 7 4.3 7 10 10.3 0 5.7 8.4 10.4 11.7 10.8 8.9

BW 4.4 4.6 4.6 5.2 2 5.2 3.5 3 4.4 3.1 2.6 3.8 5.5 7.2 6.4

*Present study. The references below each Trypanosoma species indicate where measurements were taken to compare.

Morphological location of the measured regions of Trypanosoma spp.: Total body length with flagellum (TL), body length

along the midline (BL), body width at the center of the nucleus (BW), free flagellum length (FF), distance from the center of

the nucleus to the anterior extremity (NA), distance from the center of the nucleus to the posterior extremity (NP), distance

from the center of the kinetoplast to the center of the nucleus (KN) and distance from the center of the kinetoplast to the

posterior end (KP).

10 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71: e54843, enero-diciembre 2023 (Publicado Oct. 02, 2023)

i.e. body shape, body size limits, kinetoplast

position and morphology, characteristics of

the flagellum and undulating membrane, and

morphometric índices (Baker, 1956; Bennett,

2008; Chatterjee & Ray, 1971; Molyneux, 1977;

Votýpka et al., 2004).

The diversity of trypanosome species in

Amazonian birds is still poorly known. This

may be related to logistical difficulties as well as

to technical and structural limitations (molecu-

lar biology laboratories) in the field. In our

study, we provided data on the occurrence of

Trypanosoma sp. and target species, as well as

morphological and morphometric data of one

morphotype, which could be used in more

robust studies using integrative techniques of

morphology, morphometry and molecular

biology methods. Even though the diversity of

trypanosome species is not known, it is sug-

gested that studies involving hematophagous

invertebrates be designed to better elucidate

aspects of the parasite-host relationship in

Amazonian birds.

Ethical statement: the authors declare that

they all agree with this publication and made

significant contributions; that there is no con-

flict of interest of any kind; and that we fol-

lowed all pertinent ethical and legal procedures

and requirements. All financial sources are fully

and clearly stated in the acknowledgments sec-

tion. A signed document has been filed in the

journal archives.

ACKNOWLEDGMENTS

Pedro Ferreira França would like to thank

CAPES for the grant received, the Brazilian

Forestry Service for the logistical support and

ICMBio for authorizing the capture of birds.

The author Lincoln Lima Corrêa would like

to express his gratitude for the guaranteed

and financial support granted by the CAPES/

FAPESPA project N. 06/2015-Process n°

88881.160660/2017-01. Darlison Chagas-de-

Souza and Tássio Alves Coêlho would like

to thank Coordenação de Aperfeiçoamento

de Pessoal de Nível Superior for the grant

received (Process #88887.636892/2021-00 and

#88887.598663/2021-00, respectively).

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