To cool or not to cool? Intestinal coccidians disrupt the behavioral hypothermia of lizards in response to tick infestation.

It is generally accepted that parasites exert negative effects on their hosts and that natural selection favors specific host responses that mitigate this impact. It is also known that some components of the host immune system often co-evolve with parasite antigens resulting in a host-parasite arms race. In addition to immunological components of the anti-parasitic response, host behavioral responses are also important in this arms race and natural selection may favor avoidance strategies that preclude contact with parasites, or shifts in the host's thermoregulatory strategy to combat active infections (e.g., behavioral fever). Ticks are widespread parasites with direct and indirect costs on their vertebrate hosts. Their saliva provokes hemolysis in the blood of their hosts and can transmit a plethora of tick-borne pathogens. We enquired whether tick infestation by Ixodes pacificus can provoke a thermoregulatory response in Sceloporus occidentalis. For this, we compared the thermoregulatory behavior of tick-infested lizards against tick-infested lizards co-infected with two different species of coccidians (Lankesterella occidentalis and Acroeimeria sceloporis). After this, lizards were kept in individual terraria with a basking spot and fed ad libitum. We found that tick-infested lizards sought cooler temperatures in proportion to their tick load, and this response was independent of the co-infection status by L. occidentalis. This was consistent in April and June (when tick loads were significantly lower) and suggests a conservative strategy to save energy which might have been selected to overcome tick infestations during phenological peaks of this parasite. However, this behavior was not observed in lizards co-infected with A. sceloporis, suggesting that co-infection with this intestinal parasite prompt lizards to be active. Cost of tick infestation was confirmed because housed lizards lost weight at a constant ratio to initial tick load, independently of other infections. The broader implications of these findings are discussed in the context of climate change.

Intranuclear coccidiosis in tortoises - discovery of its causative agent and transmission.

Intranuclear coccidiosis of testudines (known as TINC) is an emerging disease in chelonians. Although endogenous stages were repeatedly detected in various tissues, attempts to find the oocysts in faeces failed, leaving the question of the transmission and classification of the causative agent of TINC unresolved. We recorded small spherical oocysts (∼6-7 µm in diameter) of an eimeriid coccidium in faeces of a leopard tortoise (Stigmochelys pardalis). Sporulated oocysts were used for the experimental oral inoculation of juvenile coccidia-free tortoises representing 5 species (S. pardalis, Testudo graeca, T. hermanni, T. horsfieldii, and Geochelone sulcata). The oocysts' association with TINC was confirmed based on clinical signs, histopathological findings of intranuclear endogenous stages of the coccidium in many organs (including intestine), and by the partial 18S rDNA sequence analysis of the DNA isolated from organs of the experimentally infected animals and from a single naturally infected as well as from all experimentally infected tortoises. Breeding colonies of chelonians should be screened for this pathogen in order to prevent its further spread and unwanted introduction into endangered free-ranging chelonian populations.

Phylogeny, Morphology, and Metabolic and Invasive Capabilities of Epicellular Fish Coccidium Goussia janae.

To fill the knowledge gap on the biology of the fish coccidian Goussia janae, RNA extracted from exogenously sporulated oocysts was sequenced. Analysis by Trinity and Trinotate pipelines showed that 84.6% of assembled transcripts share the highest similarity with Toxoplasma gondii and Neospora caninum. Phylogenetic and interpretive analyses from RNA-seq data provide novel insight into the metabolic capabilities, composition of the invasive machinery and the phylogenetic relationships of this parasite of cold-blooded vertebrates with other coccidians. This allows re-evaluation of the phylogenetic position of G. janae and sheds light on the emergence of the highly successful obligatory intracellularity of apicomplexan parasites. G. janae possesses a partial glideosome and along with it, the metabolic capabilities and adaptions of G. janae might provide cues as to how apicomplexans adjusted to extra- or intra-cytoplasmic niches and also to become obligate intracellular parasites. Unlike the similarly localized epicellular Cryptosporidium spp., G. janae lacks the feeder organelle necessary for directly scavenging nutrients from the host. Transcriptome analysis indicates that G. janae possesses metabolic capabilities comparable to T. gondii. Additionally, this enteric coccidium might also access host cell nutrients given the presence of a recently identified gene encoding the molecular sieve at the parasitophorous vacuole membrane.

Caryospora bigenetica (Apicomplexa: Eimeriidae) in South America: new hosts and distribution records.

The coccidian Caryospora bigenetica was first described in the snake Crotalus horridus (Viperidae) from United States of America. This study represents the first record of the occurrence of C. bigenetica in snakes in South America. Feces were sampled between November 2013 and May 2014 from 256 wild snakes maintained in scientific breeding facilities in the states of Mato Grosso do Sul (MS; n = 214) and Rio de Janeiro (RJ; n = 42), Brazil. Caryospora bigenetica was found in 14 (5.6%) snakes, all belonging to the family Viperidae. Ten Bothrops moojeni and two Crotalus durissus from MS were infected. The coccidian was also found in one C. durissus and in one Bothrops jararacussu from the state of RJ. The oocysts were spherical with a double wall, the exterior lightly mammillated, striations apparent in transverse view, 13.0 µm (12 - 14); polar granule fixed in the internal wall. Sporocysts oval or pyriform, 10.0 × 8.0 µm (9 - 11 × 8 - 9); Stieda body discoid; sub-Stieda body present; sporocyst residuum present, formed by a group of spheroid bodies between sporozoites. This study increases the number of viperid hosts of C. bigenetica and expands the geographical distribution to South America.

Four new species of coccidia (Apicomplexa: Eimeriidae) from Owen Stanley Skinks, Papuascincus stanleyanus (Sauria: Scincidae), from Papua New Guinea.

Between September and November 1991, 12 Owen Stanley skinks, Papuascincus stanleyanus (Booulenger) were collected from various localities on Papua New Guinea and examined for coccidians. Six (50%) were found to harbour four eimerians that we describe here as new. Oocysts of Eimeria burseyi sp. n. were elongate to ellipsoidal with a bilayered wall and measured (length x width, L x W) 36.0 x 24.0 microm, with a L/W ratio of 1.5. Both micropyle and oocyst residuum were absent, but a polar granule was present. Oocysts of Eimeria goldbergi sp. n. were ellipsoidal, with a bilayered wall, and measured 21.4 x 16.1 microm; L/W ratio was 1.3. Both micropyle and oocyst residuum were absent, but a single or fragmented polar granule was present. Oocysts of Eimeria boulengeri sp. n. were spheroidal to slightly subspheroidal, with a thin, single-layered wall that readily collapses, and measured 16.0 microm, L/W ratio was 1.0. Both micropyle and oocyst residuum were absent, but usually one (sometimes two) polar granule(s) were present. Oocysts of Eimeria niuginiensis sp. n. were oblong to tapered with a bilayered wall, and measured 20.0 x 13.1 microm; L/W ratio was 1.5. A micropyle, oocyst residuum and polar granule were absent. To our knowledge, these represent the only coccidians ever described from P. stanleyanus.

New species of Choleoeimeria (Apicomplexa: Eimeriidae), coccidia of bile-bladders of reptiles, illustrating a multiplicity of host cell-parasite interrelations.

Oocyst characteristics and histological features of the endogenous development of bile-bladder coccidia of the genus Choleoeimeria Paperna and Landsberg, 1989 are described and the main features for species differentiation are discussed for the following new species: C. allogamae n. sp. from Agama sp., Cameroon, West Africa; C. allogehyrae n. sp. from Gehyra australis, Magnetic Island (type) and mainland N Queensland, Australia; C. boulii n. sp. from Gehyra variegata, SW Queensland, Australia; C. calotesi n. sp. from Calotes mystaceus, Xiang-Mai, Thailand; C. heteronotis n. sp. from Heteronotia binoei, N Queensland, Australia; C. lygosomis n. sp. from Lygosoma buringi, Kon-Kaen, Thailand; C. sylvatica n. sp. from Carlia rhomboidalis, N Queensland, Australia, and C. xiangmaii n. sp. from Hemidactylus frenatus, Xiang-Mai, Thailand. Oocyst characteristic of Choleoeimeria are also reported from Oedura castelnaui, N Queensland. The described species demonstrate a diversity of associations with the bile-bladder epithelial lining, from a single parasite in a single hypertrophic host cell to multiple infections inducing the hypertrophied cells to form stratified layers, or merge into branched clumps.

[Coccidia (Eimeriida) of perciform fishes (Perciformes) in the continental waters of Russia].

Twenty one coccidian species from the genera Eimeria and Goussia are found in the perciform fish hosts from the continental waters of Russia. Names, authors and dates of the species descriptions, synonyms, brief figured description of the morphofunctional organization of the endogenic developmental stages of coccidian, Latin and Russian names of the fish hosts are given.

Mice serve as paratenic hosts for the transmission of Caryospora duszynskii (Apicomplexa: Eimeriidae) between snakes of the genus Elaphe.

Caryospora duszynskii Upton, Current et Barnard, 1984 was successfully transmitted to snakes of the genus Elaphe by feeding them previously infected mice. Fifty thousand oocysts were orally administered to two mouse strains, BALB/c and Crl:CD-1(ICR)BR, which were subsequently fed to captive-born coccidia-free Elaphe guttata (L.) in two respective independent experiments. Both E. guttata expelled C. duszynskii oocysts in their faeces, beginning on day 18 and 26 post infection (p.i.) and shed oocysts continuously through the end of the experiment, day 230 and 135 p.i., respectively. There were no parasitic stages or lesions in mice, as revealed by histological examination. Experiments proved that rodents serve as paratenic hosts for C. duszynskii. In summary we discuss the life-cycle strategies of Caryospora spp. in reptiles and present three general modes of their development.