Parasitological studies in British Honduras. 3. Some coccidial parasites of mammals

Helminth and protozoan parasites of subterranean rodents (Chordata, Mammalia, Rodentia) of the world

Published studies and ten new unpublished records included herein reveal that approximately 174 species of endoparasites (helminths and protozoans) are known from 65 of 163 species of rodents that occupy the subterranean ecotope globally. Of those, 94 endoparasite species were originally described from these rodents. A total of 282 host-parasite associations are summarized from four major zoogeographic regions including Ethiopian, Palearctic/Oriental, Nearctic, and Neotropical. Thirty-four parasite records from the literature have been identified to only the level of the genus. In this summary, ten new records have been added, and the most current taxonomic status of each parasite species is noted. Interestingly, there are no data on endoparasites from more than 68% of described subterranean rodents, which indicates that discovery and documentation are at an early stage and must continue.

Eimeria sciurorum (Apicomplexa, Coccidia) From the Calabrian Black Squirrel (Sciurus meridionalis): An Example of Lower Host Specificity of Eimerians

Host specificity plays one of the key roles in parasitism. It affects the evolution and diversification of both host and parasite, as well as it influences their geographical distribution, and epidemiological significance. For most of parasites, however, host specificity is unknown or misrepresented because it is difficult to be determined accurately. Here we provide the information about the lower host specificity of Eimeria sciurorum infecting squirrels, and its new host record for the Calabrian black squirrel Sciurus meridionalis, a southern Italian endemic species.

A New Species of Eimeria Schneider, 1875 (Apicomplexa: Eimeriidae) from Myotis riparius Handley, 1960 (Chiroptera: Vespertilionidae) in the Atlantic Forest of Brazil, with a Checklist of Eimeria spp. Reported from Bats

INTRODUCTION

A new coccidian species of the genus Eimeria Schneider, 1875 (Apicomplexa: Eimeriidae), is reported from the bat host Myotis riparius Handley from Ilha Grande, a large island off the coast of the State of Rio de Janeiro, in southeastern Brazil.

METHODS

Bats were captured in 13 mist nets (10 × 3 m), which were set within the experimental plots, and through active searches of the daytime roosts of Molossus molossus Pallas found in Vila Dois Rios. Containment was made in bags for the collection of feces and identification of coccidia. A survey was conducted on the coccidia species described so far (Table 2).

RESULTS

The oöcysts of Eimeria riparii n. sp. are ellipsoidal to cylindroidal with an extremely thin, bi-layered wall, slightly rough. Two polar granules are present, micropyle and oöcyst residuum are both absent. The sporocysts are ellipsoidal, the sporocyst residuum is formed by sparse, rounded granules of varying sizes; the Stieda body is trapezoidal and a sub-Stieda body is absent. Sporozoites are banana shaped. With the new species described here, a total of 40 Eimeria spp. have been described infecting bat hosts, belonging to 30 species of 18 genera and 5 families.

CONCLUSION

The subsequent increase in the known diversity of bats has been derived from the ongoing expansion of research in a number of different areas of taxonomy and ecology although the number of studies of the associated coccidian parasites of the family Eimeriidae has increased more slowly.

Schellackia landauae sp.nov. (Eimeriorina: Lankesterellidae) in the Brazilian lizard Polychrus marmoratus (Iguanidae): experimental transmission by Culex pipiens fatigans

A new haemogregarine, Schellackia landauae sp.nov., is described in the Brazilian lizard Polychrus marmoratus (Linn) from Pará State, north Brazil. Sporozoites are found principally in the red blood cells (84%) in the peripheral blood but also occur in lymphocytes and monocytes. Experimental transmission to three uninfected P. marmoratus was achieved after feeding them with laboratory-bred Culex pipiens fatigans which had engorged on an infected lizard 14 days previously. The cycle of development in the small intestine of P. marmoratus takes approximately 30 days: schizogony, gametogony and fertilization of the macrogametocytes is in the epithelial cells of the gut, with zygotes penetrating the lamina propria, where the mature oocysts develop. Living oocysts average 14·3 × 13·3 μm, and are approximately 10·0 μm as seen in histological sections. During the period of intestinal development, the parasite also undergoes asexual multiplication within cells of the spleen and liver by a process which appears to be endodyogeny. The exact time required before the first invasion of the peripheral blood by the sporozoites remains to be ascertained, but is some time within 30–45 days after the lizard ingests the infected mosquitoes. Morphology of the sporozoite in the vertebrate host is variable and depends on the host cell occupied; there may be 1 or 2 refractile bodies. Reduction or fusion of these to a single refractile body in those sporozoites within the gut cells of the infected mosquito suggests that the bodies may represent some form of energy source that is used up during this latent phase in the insect vector. Accumulation of sporozoites takes place in the reticulo-endothelial cells of the viscera, in particular the pigmentladen cells of the liver and lung. Attempts to infect other species of lizards, Tropidurus torquatus (Iguanidae) and Ameiva ameiva (Teiidae) failed.

Blood and intestinal parasites of squirrels (Rodentia: Sciuridae) in Amazonian Brazil

We report the result of an examination for blood and intestinal protozoa in 12 specimens of the red squirrel Sciurus spadiceus (Rodentia: Sciuridae) from Birroque, municipality of Placido de Castro, state of Acre, Brazil. No parasites were detected in thin, Giemsa-stained blood films of the animals, but culture of the blood of three in Difco B45 medium blood-agar slants gave rise to isolates of epimastigotes. Inoculation of one isolate into laboratory mice resulted in the appearance of Trypanosoma cruzi-like trypomastigotes in their peripheral blood, and the other two isolates gave rise to transient infections with a T. lewisi-like parasite in inoculated mice and hamsters. The failure of the latter parasite to develop in the triatomine bug Rhodnius robustus suggests that it is probably not T. rangeli. This appears to be the first record of a T. lewisi-like trypanosome in neotropical squirrels. Oocysts of an Eimeria sp., were detected in the faeces of 10 animals (83.3%). The parasite develops in the epithelial cells of the intestine, where it may cause severe damage and sometimes results in death of the animal. No oocysts were detected in bile.

Eimeria peltocephali n. sp., (Apicomplexa:Eimeriidae) from the freshwater turtle Peltocephalus dumerilianus (Chelonia:Pelomusidae) and Eimeria molossi n. sp., from the bat, Molossus ater (Mammalia:Chiroptera)

The oocyst is described of Eimeria peltocephali n.sp. from faeces of the freshwater turtle Peltocephalus dumerilianus from Barcelos, State of Amazonas, Brazil. Sporulation is exogenous and fully developed oocysts are elongate, ellipsoidal or cylindrical, frequently curved to a banana-shape, 54.4 x 19.1 (37.5-68.7 x 18.7-20.0 microns), shape-index 2.8 (1.8-3.9). The oocyst wall is a single thin, colourless layer about 1 micron thick, with no micropyle. There is a bulky oocyst residuum, at first spherical to ellipsoidal, 19 x 16 (16.2-26.2 x 16-21.5 microns), but becoming dispersed on maturation. There are no polar bodies. The sporocysts, 19.1 x 6.8 (17.5-21.2 x 6.2-7.5 microns), shape-index 2.8 (2.3-3.2), are usually disposed in pairs at each end of the oocyst, and bear an inconspicuous Stieda body in the form of a flat cap. The sporozoites are elongate and slightly curved around the residuum. No refractile bodies were seen. Eimeria molossi n.sp., is described from the molossid bat Molossus ater. Sporulation is exogenous and the mature oocysts are predominantly broadly ellipsoidal, 23.4 x 17.5 (18-30 x 15-22.5 microns), shape-index 1.3 (1-1.6). The oocyst wall is about 2 microns thick, and of three layers: an inner thin, colourless one and two outer layers which are thicker, yellowish-brown, prominently striated and in close apposition. There is no micropyle or oocyst residuum, but one and occasionally two polar bodies are usually present. Sporocysts are ellipsoidal, 10.2 x 7.5 (10-12.5 x 7.5 microns), shape-index 1.4 (1.3-1.7) with an inconspicuous Stieda body. Endogenous stages are described in the epithelial cells of the small intestine.

Coccidia of Brazilian mammals: Eimeria marajoensis N. Sp. (Apicomplexa: Eimeriidae) from the Anteater, Tamandua tetradactyla (Xenarthra: Myrmecophagidae)

Feces from a juvenile specimen of the anteater Tamandua tetradactyla from Ponta de Pedras, Marajó, Pará, northern Brazil, contained three different coccidial oocysts: Eimeria tamanduae Lainson, 1968; E. corticulata Lainson & Shaw, 1990; and a third species previously unrecorded and described here as Eimeria marajoensis n. sp. Oocysts of the latter parasite are spherical to subspherical, 13.9 +/- 1.5 x 13.4 +/- 1.4 (11.1-16.5 x 11.1-16.5) microns, shape index (length/width) 1.0 (1.0-1.2). The oocyst wall is a single, colorless layer about 0.6-1.0 microns thick with no striations or micropyle. There is no oocyst residuum, but a single, round, oval or irregularly shaped polar granule of about 0.75-2.5 microns is consistently present. The sporocysts are broadly ellipsoidal, 7.1 +/- 0.7 +/- 5.3 +/- 0.6 (6.0-8.8 x 4.0-5.7) microns, shape index 1.3 (1.2-1.5), with a delicate wall bearing minute stieda body. No sub-stieda body was visible. The sporocyst residuum consists of some 10-20 rounded granules, lying between the two slightly curved sporozoites which measure approximately 6.5 x 2.0 microns. Sporocyst refractile bodies were not discernable.

Coccidia of Brazilian mammals: Eimeria corticulata n. sp. (Apicomplexa: Eimeriidae) from the anteater Tamandua tetradactyla (Xenarthra: Myrmecophagidae) and Eimeria zygodontomyis n. sp. from the cane mouse Zygodontomys lasiurus (Rodentia: Cricetidae)

Feces from a specimen of Tamandua tetradactyla (Linn.) from Portel, Pará State, north Brazil, contained two different coccidial oocysts; one identified as Eimeria tamanduae Lainson 1968, and the other as a new species, described here as Eimeria corticulata n. sp. Oocysts of E. corticulata are ellipsoidal, 37.4 x 30.4 (31.2-43.7 x 23.7-35.0) microns, shape index (length/width) 1.2 (1.0-1.5). Oocyst wall 2.5-3.7 microns thick and composed of two layers; an outer thick, brown-yellow one with radial striations, and a thin inner smooth one: no visible micropyle. Oocyst residuum a large globule of about 10.7 x 10.3 microns, usually accompanied by a number of smaller attached globules. Sporocysts ellipsoidal, 21.0 x 11.0 (20.0-22.5 x 10.0-12.5) microns, with a conspicuous Stieda body; shape index 1.9 (1.6-2.2). Sporocyst residuum a small number of scattered granules: sporozoites 18.7 x 5.0 microns, with a large posterior refractile body. Eimeria zygodontomyis n. sp. is described in feces from Zygodontomys lasiurus (Lund) from the Serra dos Carajás, Pará. Oocysts ellipsoidal to cylindrical, 16.5 x 12.0 (13.7-18.7 x 11.2-12.3) microns, shape index 1.4 (1.2-1.5). Wall colorless, smooth, single-layered and about 0.6 micron thick: no micropyle. No oocyst residuum, but a polar granule of about 1.8 x 1.0 microns is sometimes present. Sporocysts ellipsoidal, 8.4 x 5.5 (7.5-8.7 x 5.0-6.2) microns, shape index 1.5 (1.4-1.7), with a thin colorless wall and a delicate Stieda body. Sporozoites enclose a compact residuum of about 2.5 x 3.7 microns.

Coccidia (Apicomplexa: Eimeriidae) from sciurid rodents (Eutamias, Sciurus, Tamiasciurus spp.) from the western United States and northern Mexico with description of two new species

Since May 1979, 190 rodents in the family Sciuridae, representing three genera and nine species, have been collected in the western United States and northern Mexico and examined for coccidia; 71 (37%) had coccidian oocysts in their feces. These included 2 of 12 (17%) Eutamias canipes; 7 of 12 (58%) E. dorsalis; 18 of 50 (36%) E. merriami; 33 of 96 (34%) E. obscurus; 3 of 4 (75%) E. townsendii; 3 of 9 (33%) Sciurus aberti; 1 of 1 S. griseus; 1 of 1 Tamiasciurus hudsonicus mogollonensis; and 3 of 5 (60%) T. mearnsi. The following coccidians were identified from infected rodents: Eimeria cochisensis n. sp. and Eimeria dorsalis n. sp. from E. canipes, E. cochisensis, E. dorsalis, and E. tamiasciuri from E. dorsalis, E. dorsalis and E. tamiasciuri from E. merriami; E. cochisensis, E. dorsalis, E. tamiasciuri, and E. wisconsinensis from E. obscurus; E. cochisensis and E. dorsalis from E. townsendii; E. ontarioensis and E. tamiasciuri from S. aberti; E. tamiasciuri from S. griseus; E. tamiasciuri and E. toddi from T. h. mogollonensis; and E. tamiasciuri from T. mearnsi. Sporulated oocysts of Eimeria dorsalis n. sp. were ovoid, 21.9 x 16.8 (17-24 x 14-20) micrometer with sporocysts ovoid, 11.5 x 6.9 (10-14 x 6-8) micrometer. Sporulated oocysts of Eimeria cochisensis n. sp. were spheroid to subspheroid, 16.7 x 15.3 (15-18 x 14-17) micrometer, with sporocysts ovoid, 8.4 x 5.6 (6-11 x 4-7) micrometer. Fifty-five of 71 (77%) infected hosts had oocysts of only one eimerian species in their feces at the time they were examined. One eimerian, E. tamiasciuri, was found in seven of nine host species in three genera. A list is provided of all eimerians (22, including the species described here) that have been described in the literature from Eutamias, Sciurus, and Tamiasciurus spp.