Endoparasitic helminth fauna and diet of Geophagus sveni (Pisces) in Upper Paraná River basin.

In freshwater ecosystems, parasite infection patterns are influenced by factors including spatial-temporal variations, host diet, and habitat. Fish often change diets, affecting their parasite communities. This study focused on non-native host fish Geophagus sveni, aiming to characterize diet and endoparasitic helminth fauna patterns in the invaded area, investigating spatial and seasonal possible differences of endoparasite infections and correlating with host diet, in São José dos Dourados River and Tietê River areas. The host fish were collected in these areas during the dry and rainy season using gillnets. The endoparasites were collected and preserved in alcohol and identified using taxonomic methods, and stomach contents were examined for diet analysis. Parasitism descriptors were calculated and evaluated spatially and seasonally by ANOVA and the Kruskal-Wallis tests. PERMANOVA assessed G. sveni diet differences, and RDA correlated the endohelminth abundance with the host diet. Two endoparasites were recorded: metacercariae of Austrodiplostomum compactum (Trematoda) and larvae and adults of Raphidascaris (Sprentascaris) lanfrediae (Nematoda). Spatial differences were observed for the mean abundance and prevalence of R. (S.) lanfrediae and A. compactum prevalence. Seasonal variations of parasitic descriptors occurred for the nematode in the Tietê River area. The detritus and aquatic insects were the most consumed items by G. sveni. Detritus consumption positively correlates with nematode abundance. The findings indicate that factors such as artificial channels and rainfall, which can influence resource availability, may affect the fish's diet and potentially influence the structure of its endoparasite community. The study emphasizes the importance of understanding trophic chain-transmitted parasites and calls for further research in Neotropical environments.

Molecular detection and identification of Leishmania DNA and blood meal analysis in Phlebotomus (Larroussius) species.

BACKGROUND: Phlebotomus (Larroussius) perniciosus and Canis familiaris are respectively the only confirmed vector and reservoir for the transmission of Leishmania (L.) infantum MON-1 in Tunisia. However, the vector and reservoir hosts of the two other zymodemes, MON-24 and MON-80, are still unknown. The aim of this study was to analyze the L. infantum life cycle in a Tunisian leishmaniasis focus. For this purpose, we have focused on: i) the detection, quantification and identification of Leishmania among this sand fly population, and ii) the analysis of the blood meal preferences of Larroussius (Lar.) subgenus sand flies to identify the potential reservoirs. METHODOLOGY AND FINDINGS: A total of 3,831 sand flies were collected in seven locations from the center of Tunisia affected by human visceral leishmaniasis. The collected sand flies belonged to two genus Phlebotomus (Ph.) (five species) and Sergentomyia (four species). From the collected 1,029 Lar. subgenus female sand flies, 8.26% was positive to Leishmania by ITS1 nested PCR. Three Leishmania spp. were identified: L. infantum 28% (24/85), L. killicki 13% (11/85), and L. major 22% (19/85). To identify the blood meal sources in Ph. Lar. subgenus sand flies, engorged females were analyzed by PCR-sequencing targeting the vertebrate cytochrome b gene. Among the 177 analyzed blood-fed females, 169 samples were positive. Sequencing results showed seven blood sources: cattle, human, sheep, chicken, goat, donkey, and turkey. In addition, mixed blood meals were detected in twelve cases. Leishmania DNA was found in 21 engorged females, with a wide range of blood meal sources: cattle, chicken, goat, chicken/cattle, chicken/sheep, chicken/turkey and human/cattle. The parasite load was quantified in fed and unfed infected sand flies using a real time PCR targeting kinetoplast DNA. The average parasite load was 1,174 parasites/reaction and 90 parasites/reaction in unfed and fed flies, respectively. CONCLUSION: Our results support the role of Ph. longicuspis, Ph. perfiliewi, and Ph. perniciosus in L. infantum transmission. Furthermore, these species could be involved in L. major and L. killicki life cycles. The combination of the parasite detection and the blood meal analysis in this study highlights the incrimination of the identified vertebrate in Leishmania transmission. In addition, we quantify for the first time the parasite load in naturally infected sand flies caught in Tunisia. These findings are relevant for a better understanding of L. infantum transmission cycle in the country. Further investigations and control measures are needed to manage L. infantum transmission and its spreading.

First evidence of the presence of Anisakis simplex in Crangon crangon and Contracaecum osculatum in Gammarus sp. by in situ examination of the stomach contents of cod (Gadus morhua) from the southern Baltic Sea.

Cod (Gadus morhua), an important fish species in the Baltic Sea, is the paratenic host for many parasite species, including the zoonotic nematodes, Anisakis sp. and Contracaecum osculatum. We aimed to identify which invertebrate species (found in situ in the fish stomach) are responsible for infection of cod with zoonotic nematodes. We found that Crangon crangon and Gammarus sp., both invertebrate prey species of cod, were infected with Anisakis simplex and C. osculatum, respectively. These host-parasite systems are reported here for the first time, implicating C. crangon and Gammarus sp. as sources of infection of Baltic cod with zoonotic nematodes.

Microplastics in grey seal (Halichoerus grypus) intestines: Are they associated with parasite aggregations?

Between 2012 and 2015, 13 grey seals were recovered from trammel nets targeting monkfish and rays off the south coast of Ireland. Incidence and distribution of microplastics were investigated along the intestines of bycaught seals. No macrodebris items were found, whereas microplastics were detected in all seals. A total of 363 microplastics items were identified (85% fibers, 14% fragments, 1% films). Estimation of microplastic ingestion based on prey ingestion (245 particles) was lower than the observed data. Acantocephala parasites (n = 1543) were found in 12 seals, with an average of 74.5 ±â€¯67.7 parasites per seal. Distribution of microplastics varied between seals, although microplastics tended to accumulate in areas where more parasites were aggregated; however, there was no significant relationship between the number of parasites and microplastics was found. Seals recovered from nets appear to be a good source to monitor the incidence of microplastic pollution within the coastal food webs.

Host specificity and age-dependent resistance to Cryptosporidium avium infection in chickens, ducks and pheasants.

Host- and age-specificity of Cryptosporidium avium were studied in 1-, 21- and 365-day-old chickens (Gallus gallus), domestic ducks (Anas platyrhynchos) and ring-necked pheasants (Phasianus colchicus) under experimental conditions. Cryptosporidium avium was not infectious for ring-necked pheasants, but it was infectious for ducks and chickens at all age categories. The course of infection in ducks did not differ among age categories, but 365-day-old chickens had less severe infections than 1- and 21-day-old chickens. The patent period in chickens and ducks was >30 DPI, but ducks started to shed oocysts of C. avium earlier (5-6 DPI) and at a lower intensity (accumulated value of infection intensity of 58,000-65,000 OPG) than chickens (9-11 DPI and accumulated value of infection intensity of 100,000-105,000 OPG). Experimentally infected birds showed no clinical signs of cryptosporidiosis.

Sarcocystis pantherophisi n. sp., from Eastern Rat Snakes (Pantherophis alleghaniensis) as Definitive Hosts and Interferon Gamma Gene Knockout Mice as Experimental Intermediate Hosts.

Here, we report a new species, Sarcocystis pantherophisi n. sp., with the Eastern rat snake (Pantherophis alleghaniensis) as natural definitive host and the interferon gamma gene knockout (KO) mouse as the experimental intermediate host. Sporocysts (n = 15) from intestinal contents of the snake were 10.8 × 8.9 µm. Sporocysts were orally infective to KO mice but not to laboratory-raised albino outbred house mice (Mus musculus). The interferon gamma KO mice developed schizont-associated neurological signs, and schizonts were cultivated in vitro from the brain. Mature sarcocysts were found in skeletal muscles of KO mice examined 41 days postinoculation (PI). Sarcocysts were slender, up to 70 µm wide and up to 3.5 mm long. By light microscopy, sarcocysts appeared thin-walled (<1 µm) without projections. By transmission electron microscopy, the sarcocyst wall was a variant of "type 1" (type 1i, new designation). The parasitophorous vacuolar membrane (pvm) had approximately 100-nm-wide × 100-nm-long bleb-like evaginations interspersed with 100-nm-wide × 650-nm-long elongated protrusions at irregular distances, and invaginations into the ground substance layer (gs) for a very short distance (6 nm). The gs was smooth, up to 500 nm thick, without tubules, and contained a few vesicles. Longitudinally cut bradyzoites at 54 days PI were banana-shaped, 7.8 × 2.2 µm (n = 5). Molecular characterization using 18S rRNA, 28S rRNA, ITS-1, and cox1 genes indicated a close relationship with other Sarcocystis parasites that have snake-rodent life cycles. The parasite in the present study was molecularly and biologically similar to a previously reported isolate (designated earlier as Sarcocystis sp. ex Pantherophis alleghaniensis) from P. alleghaniensis, and it was structurally different from other Sarcocystis species so far described.

Survival of Toxoplasma gondii tachyzoites in simulated gastric fluid and cow's milk.

The protozoan parasite Toxoplasma gondii is one of the most important food-related pathogens worldwide. Besides contact to oocysts or ingestion of tissue cysts mainly by consumption of raw or undercooked meat from infected animals, raw milk is considered to be a risk factor and possible route of transmission for tachyzoites. This stage of the parasite is usually very sensitive to acidic pH and, therefore, considered unlikely to survive stomach passage. However, tachyzoites were shown to survive for several days in milk and there are also reports on transmission of toxoplasmosis via milk. Thus, the aim of the study was to examine retention of infectivity of tachyzoites in simulated gastric fluid (SGF) of different acidity and to elucidate whether addition of different shares of milk would affect survival of the parasites. Tachyzoites were exposed to SGF of pH 2.0 through 6.0 and their remaining infectivity was examined by cell culture. Furthermore, the impact on survival was investigated in different admixtures of milk to the SGF (25, 50, 75%) as well as in pure milk. Tachyzoites were shown to retain infectivity in SGF of pH 5.0 and 6.0 for at least 90min while they were more sensitive to lower pH values. Admixture of milk resulted in extension of survival. The results support the hypothesis of tachyzoites to survive stomach passage and their retention of infectivity.

Effect of Entodinium caudatum on starch intake and glycogen formation by Eudiplodinium maggii in the rumen and reticulum.

This study aimed to quantify the engulfed starch and reserve α-glucans (glycogen) in the cells of the ciliates Eudiplodinium maggii, as well the α-glucans in defaunated and selectively faunated sheep. The content of starch inside the cell of ciliates varied from 21 to 183mg/g protozoal DM relative to the rumen fauna composition whereas, the glycogen fluctuated between 17 and 126mg/g dry matter (DM) of this ciliate species. Establishment of the population Entodinium caudatum in the rumen of sheep already faunated with E. maggii caused a drop in both types of quantified carbohydrates. The content of α-glucans in the rumen of defaunated sheep varied from 4.4 to 19.9mg/g DM and increased to 7.4-29.9 or 11.8-33.9mg/g DM of rumen contents in the presence of only E. maggii or E. maggii and E. caudatum, respectively. The lowest content of the carbohydrates was always found just before feeding and the highest at 4h thereafter. The α-glucans in the reticulum varied 7.5-40.1, 14.3-76.8 or 21.9-106.1mg/g DM of reticulum content for defaunated, monofaunated or bifaunated sheep, respectively. The results indicated that both ciliate species engulf starch granules and convert the digestion products to the glycogen, diminishing the pool of starch available for amylolytic bacteria.

Reclassification of Eimeria pogonae Walden (2009) as Choleoeimeria pogonae comb. nov. (Apicomplexa: Eimeriidae).

The presented paper provides a reclassification of Eimeria pogonae from Pogona vitticeps into the correct genus Choleoeimeria. A description of exogenous and endogenous stages of biliary coccidium is given. Sporulation of the oocysts was endogenous. The mature oocysts contained four sporocysts each with two sporozoites. Oocysts were ellipsoidal in shape, with average length/width ratio 1.7 and measured 28.4 (SD1.5) × 16.8 (SD 1.5). The micropyle, residuum, and polar granules were absent from the sporulated oocysts. Ovoidal in shape, sporosysts without Steida bodies contained residuum and two elongated and boat-shaped sporozoites. The endogenous stages of the coccidia were located mainly in the epithelium of bile ducts; however, single-epithelium cells of the gallbladder were also infected.

The use of genetically marked infection cohorts to study changes in establishment rates during the time course of a repeated Ascaridia galli infection in chickens.

This study investigated the changes in establishment rates during the time course of a 6 week trickle infection of chickens with Ascaridia galli at two different dose levels, using a molecular marker. To differentiate early and late infection, two different egg cohorts (haplotype a and haplotype b, genetically identified using PCR-linked restriction fragment length polymorphism on the cox1 gene of the mitochondrial DNA) were used. Cohort-specific egg batches were produced by harvesting eggs from the uteri of female worms of the specific cohort. Fifty-six 8 week old Lohmann Brown Lite chickens were divided into seven groups and the infectivity of the egg batches was compared between two groups of chickens (P=0.6). The remaining chickens were allocated to four infection regimes and one control group. Group ab100 was trickle infected for 3 weeks with 100 eggs of haplotype a (twice weekly) followed by the same dose of eggs of haplotype b for another 3 weeks. Group ba100 was treated similarly but in the opposite order (haplotype b preceding a). A similar infection regime was applied for groups ab25 and ba25 but with a lower inoculation dose (25 eggs). All of the birds in these five groups (four infected and one control) were euthanased 2 weeks after the last inoculation. It was found that in the low-dose groups both the early and late infections established equally well, whereas in the high-dose groups the early infection was recovered in a significantly (P<0.001) higher proportion of chickens than the late infection, irrespective of genetic cohorts. Moreover, relatively higher proportions of the larvae from both the early and late infections were found in the posterior section of the small intestine. This result indicates the presence of dose-dependent resistance against reinfection and this resistance seems to act by reducing the establishment of late infection and by relocating the larvae from early infection.

Shedding of zoonotic pathogens and analysis of stomach contents in great cormorants (Phalacrocorax carbo sinensis) from Switzerland between 2007 and 2012.

208 healthy great cormorants (Phalacrocorax carbo sinensis) shot during 5 consecutive hunting seasons from 2007/2008 until 2011/2012 were tested for Newcastle disease virus (APMV-1), avian influenza virus (AIV), Chlamydiae, and Salmonella spp. In addition, stomach contents were gross macroscopically examined. None of the birds was positive for APMV1, AIV or Chlamydiae. Twice Salmonella enterica subsp. enterica serovar Typhimurium and once a rough mutant of Salmonella Typhimurium were found. Stomach worms were found in 199 cormorants and 12 identifiable fish species in 45 stomaches.

208 cormorans sauvages en bonne santé (Phalacrocorax carbo sinensis), tirés au cours de 5 années de chasse consécutives, de 2007/2008 à 2011/2012, ont été testés quant au virus de la maladie de Newcastle (APMV1), au virus de l'influenza aviaire (AIV), aux chlamydias et aux Salmonella spp. Tous les oiseaux étaient négatifs en ce qui concerne APMV-1, AIV et chlamydias. On a isolé deux fois Salmonella enterica subsp. enterica serovar Typhimurium et une fois une forme de base de Salmonella Typhimurium. En outre on a examiné macroscopiquement le contenu stomacal. 199 cormorans étaient atteints de vers gastriques et on a pu identifier, dans 45 estomacs, 12 sortes de poissons différents.

Studies on the in vitro cultivation of ciliate protozoa from the kangaroo forestomach.

The methods used for culturing rumen protozoa were found to be unsatisfactory for growth of ciliate protozoa from the kangaroo forestomach. Based on published measurements of physical parameters in the marsupial forestomach, several modifications were incorporated into the procedure, i.e., an increase in % hydrogen in the gas phase, adjustment of initial pH of the medium to 6.9-7.0 range, feed only forage as a substrate and incubate at a lower temperature (33-36 °C). Only incubation at the lower temperature increased survival time of the kangaroo protozoa. Two species of Bitricha were still viable after 28 d in culture. Cultures had to be terminated at that time. One of the species differed considerably in size and shape from previously described species and based on 18S rRNA data, may represent a new species of Bitricha. The second species, present in low numbers was identified as Bitricha oblata. In a separate trial, Macropodinium yalanbense survived for 11 d, at which time these cultures also had to be terminated.

Increase in number of helminth species from Dutch red foxes over a 35-year period.

BACKGROUND: The red fox (Vulpes vulpes) is host to a community of zoonotic and other helminth species. Tracking their community structure and dynamics over decades is one way to monitor the long term risk of parasitic infectious diseases relevant to public and veterinary health. METHODS: We identified 17 helminth species from 136 foxes by mucosal scraping, centrifugal sedimentation/flotation and the washing and sieving technique. We applied rarefaction analysis to our samples and compared the resulting curve to the helminth community reported in literature 35 years ago. RESULTS: Fox helminth species significantly increased in number in the last 35 years (p-value <0.025). Toxascaris leonina, Mesocestoides litteratus, Trichuris vulpis and Angiostrongylus vasorum are four new veterinary-relevant species. The zoonotic fox tapeworm (E. multilocularis) was found outside the previously described endemic regions in the Netherlands. CONCLUSIONS: Helminth fauna in Dutch red foxes increased in biodiversity over the last three decades.

Detection of Echinococcus multilocularis in faeces by nested PCR with the use of diluted DNA samples.

The aim of this study was to choose the optimal variant of PCR examination of faeces to detect Echinococcus multilocularis infection which would allow to reduce the influence of different inhibitors in faeces. The investigation was carried out by comparison of 3 different methods of DNA isolation from faeces and different DNA dilutions used in PCR. Thirty five intestines of red foxes were used. Small intestines were examined by the sedimentation and counting technique (SCT). Faeces were collected from the rectum for PCR and flotation. DNA were isolated with the use of 3 different methods. Two methods were dedicated for faeces: method 1 (M1)--for larger samples and method 2 (M2) - for standard samples. The third method, method 3 (M3), was not dedicated for faeces. DNA samples were tested by nested PCR in 6 variants: not diluted (1/1) and 5 diluted (1/2.5, 1/5, 1/10. 1/20, 1/40). E. multilocularis was found by SCT in 18 from 35 (51.4%) intestines. Taenia-type eggs were detected only in 20.0% of faecal samples. In PCR the highest number of positive results (45.7%) were obtained during examination of DNA isolated by M1 method, and then 40.0% and 34.3%, respectively, for M2 and M3. In some samples positive results in PCR were obtained only in diluted DNA. For example, 8 from 12 positive samples isolated by M3 method gave the PCR negative results in non-diluted DNA and positive only after dilution 1:2.5, 1:10 or 1:20. Also 3 samples isolated by methods dedicated for stool gave positive results only after DNA dilution. The investigation has revealed that in copro-PCR for detection of E. multilocularis infection additional using of diluted DNA (besides non diluted) can avoid false negative results causing by PCR inhibition. In the best method of DNA isolation (M1), the use of non diluted DNA sample together with diluted in proportion 1:10 seems to be optimal.

Blastocystis tropism in the pig intestine.

Blastocystis has been reported in pig feces but the sites of development in the gastrointestinal tract are unknown. The present study was undertaken to determine predilection sites of Blastocystis in 11 naturally infected pigs examined at 20 weeks of age. At necropsy, feces and contents of the duodenum, jejunum, ileum, and cecum were examined by immunofluorescence (IFA) microscopy and PCR and tissues from these sites as well as the proximal and distal colon were processed for histology from pigs 1 to 5. Feces were examined by IFA microscopy, and segments from the jejunum and ileum were processed for histology from pigs 6 to 11. Multiple sections were cut from each tissue segment, and each was stained with the following: hematoxylin and eosin, polyclonal rabbit antibody to Blastocystis, and ParaFlor B monoclonal antibody to Blastocystis. Blastocystis was detected in feces of all 11 pigs by IFA microscopy and determined by PCR and gene sequencing to be subtype 5 for pigs 1-5. Blastocystis was also detected in the lumen contents removed from the cecum of pigs 1-5 examined by IFA microscopy and in the cecum of pigs 4 and 5 by PCR. Blastocystis was also observed in tissue sections from the jejunum of 7 of the 11 pigs, in the proximal and distal colon of pigs 1-5, and in the cecum of 4 of these 5 pigs but was not detected in the duodenum or ileum of any pigs. In tissue sections, Blastocystis was found primarily in the lumen usually associated with digested food debris, sometimes in close proximity or appearing to adhere to the epithelium, but no stages were found to penetrate the epithelium or the lamina propria.

Tritrichomonas foetus: prevalence study in naturally mating bulls in Switzerland.

Switzerland is officially free from bovine Tritrichomonas foetus. While bulls used for artificial insemination (AI) are routinely examined for this pathogen, bulls engaged in natural mating, as well as aborted fetuses, are only very sporadically investigated, indicating that the disease awareness for bovine tritrichomoniasis is low. Natural mating in cattle is becoming increasingly popular in Switzerland. Accordingly, a re-introduction/re-occurrence of T. foetus in cattle seems possible either via resurgence from a yet unknown bovine reservoir, or via importation of infected cattle. The low disease awareness for bovine tritrichomoniasis might favor an unnoticed re-establishment of T. foetus in the Swiss cattle population. The aim of our study was thus to search for the parasite, and if found, to assess the prevalence of bovine T. foetus in Switzerland. We included (1) bulls over two years of age used in natural mating and sent to slaughter, (2) bulls used for natural service in herds with or without fertility problems and (3) aborted fetuses. Furthermore, the routinely examined bulls used for AI (4) were included in this study. In total, 1362 preputial samples from bulls and 60 abomasal fluid samples of aborted fetuses were analyzed for the presence of T. foetus by both in vitro cultivation and molecular analyses. The parasite could not be detected in any of the samples, indicating that the maximal prevalence possibly missed was about 0.3% (95% confidence). Interestingly, in preputial samples of three bulls of category 1, apathogenic Tetratrichomonas sp. was identified, documenting a proof-of-principle for the methodology used in this study.

Evidence for an amoeba-like infectious stage of Ichthyophonus sp. and description of a circulating blood stage: a probable mechanism for dispersal within the fish host.

Small amoeboid cells, believed to be the infectious stage of Ichthyophonus sp., were observed in the bolus (stomach contents) and tunica propria (stomach wall) of Pacific staghorn sculpins and rainbow trout shortly after they ingested Ichthyophonus sp.-infected tissues. By 24-48 hr post-exposure (PE) the parasite morphed from the classically reported multinucleate thick walled schizonts to 2 distinct cell types, i.e., a larger multinucleate amoeboid cell surrounded by a narrow translucent zone and a smaller spherical cell surrounded by a "halo" and resembling a small schizont. Both cell types also appeared in the tunica propria, indicating that they had recently penetrated the columnar epithelium of the stomach. No Ichthyophonus sp. pseudo-hyphae ("germination tubes") were observed in the bolus or penetrating the stomach wall. Simultaneously, Ichthyophonus sp. was isolated in vitro from aortic blood, which was consistently positive from 6 to 144 hr PE, then only intermittently for the next 4 wk. Small PAS-positive cells observed in blood cultures grew into colonies consisting of non-septate tubules (pseudo-hyphae) terminating in multinucleated knob-like apices similar to those seen in organ explant cultures. Organ explants were culture positive every day; however, typical Ichthyophonus sp. schizonts were not observed histologically until 20-25 days PE. From 20 to 60 days PE, schizont diameter increased from ≤ 25 µm to ≥ 82 µm. Based on the data presented herein, we are confident that we have resolved the life cycle of Ichthyophonus sp. within the piscivorous host.

Rumen fermentation and microbial population in lactating dairy cows receiving diets containing oilseeds rich in C-18 fatty acids.

Sixteen Holstein rumen-cannulated primiparous milking dairy cows were fed a control diet (CN) based on maize silage and soyabean meal during a 4-week period before the start of a 21-d experiment with oilseeds containing high concentration of linoleic acid (Linola™) or linolenic acid (NuLin™). Thereafter, four cows received ad libitum one of each of four dietary treatments comprising of CN, Linola (LN), NuLin (NL) and LN/NL (50/50 % combination). Each LN, NL and LN/NL treatment contained 6 % oil of DM. Rumen digesta samples were collected on days 6, 11, 16 and 21 and milk samples on days 13, 15 and 17. There were no effects (P>0.05) of the oilseeds on pH and concentrations of NH3-N and total volatile fatty acids, while the acetate:propionate ratio was decreased (P< 0.05). The oilseeds also decreased (P< 0.05) protozoa and increased (P< 0.1) total cellulolytic bacteria in rumen fluid, especially when containing high dietary linoleic acid (P< 0.05). The milk protein concentration was increased (P< 0.1) by the dietary linoleic acid, which produced most beneficial results. It was concluded that supplements of linoleic acid in diets of ruminants might contribute to better digestion of dietary fibre and increased quality of milk.

Host selection and parasite infection in Aedes taeniorhynchus, endemic disease vector in the Galápagos Islands.

Host selection in blood-sucking arthropods has important evolutionary and ecological implications for the transmission dynamics, distribution and host-specificity of the parasites they transmit. The black salt-marsh mosquito (Aedes taeniorhynchus Wiedemann) is distributed throughout tropical to temperate coastal zones in the Americas, and continental populations are primarily mammalphilic. It is the only indigenous mosquito in the Galápagos Islands, having colonised the archipelago around 200,000 years ago, potentially adapting its host selection, and in the process, altering the dynamics of vector mediated pathogen interactions in the archipelago. Here, we use blood-meal analysis and PCR-based parasite screening approach to determine the blood-feeding patterns of A. taeniorhynchus in the Galápagos Islands and identify potential parasite transmission with which this mosquito could be involved. Our results show that A. taeniorhynchus feeds equally on mammals and reptiles, and only one avian sample was observed in 190 successful PCR amplifications from blood meals. However, we detected endemic filarial worms and Haemoproteus parasites known to infect various Galápagos bird species in mosquito thoraces, suggesting that feeding on birds must occur at low frequency, and that A. taeniorhynchus may play a role in maintaining some avian vector-borne pathogens, although more work is needed to explore this possibility. We also isolated three different DNA sequences corresponding to hemogregarine parasites of the genus Hepatozoon from mosquito and iguana blood samples, suggesting that more than one species of Hepatozoon parasites are present in Galápagos. Phylogenetic analysis of Hepatozoon 18sRNA sequences indicates that A. taeniorhynchus may have facilitated a recent breakdown in host-species association of formerly isolated Hepatozoon spp. infecting the reptile populations in the Galápagos Islands.

Epimastigogénesis de Trypanosoma cruzi: método para estudiar in vivo la transformación de tripomastigota en epimastigota / Trypanosoma cruzi epimastigogenesis: a method for studying Trypomastigote to epimastigote transformation in vivo

La epimastigogénesis de Trypanosoma cruzi ocurre naturalmente en el intestino del hospedador invertebrado. Se desconoce si los cambios morfológicos que ocurren durante la transformación de los tripomastigotas sanguíneos en epimastigotas son idénticos para diferentes aislados de T. cruzi. Aquí mostramos un método útil para estudiar los eventos que ocurren durante la epimastigogénesis, comparando parásitos de diferentes procedencias epidemiológicas. Se alimentaron artificialmente ninfas de V estadio de Rhodnius prolixus con una solución ad hoc conteniendo tripomastigotas tipo-sanguíneo y siguiendo los cambios morfológicos por 8 días. Los contenidos del intestino anterior de las ninfas se obtuvieron decapitando y comprimiendo el abdomen lo que permitió obtener rápidamente casi 100% del inóculo con cargas entre 1,9 y 8,9 × 106 tripomastigotas/ninfa. El número de parásitos por ninfa y los cambios morfológicos se determinaron por Microscopia de Contraste de Fases y coloración con Giemsa. Las ninfas ingirieron 7,4 veces su peso de solución infectante, con volúmenes entre 101 y 357 µL (229 ± 66 mg), 50% de esa ingesta se eliminó como orina durante las primeras 24 h. Los tripomastigotas se transformaron en formas redondeadas antes de evolucionar a epimastigotas, siguiendo cinéticas diferentes según el aislado. Proponemos esta metodología para estudiar rápida y cuantitativamente los eventos tempranos de la epimastigogénesis de T. cruzi in vivo.

Trypanosoma cruzi epimastigogenesis naturally occurs in the intestine of the invertebrate host. It is not known whether the morphological changes that occur during transformation of bloodstream trypomastigotes to epimastigotes are identical for different T. cruzi isolates. This research shows a useful method for studying the events that occur during epimastigogenesis, comparing parasites from epidemiological sources. Rhodnius prolixus V stage nymphs were fed artificially with an ad hoc solution containing blood-like trypomastigotes and the morphological changes were examined during eight days. Anterior intestinal contents were removed by decapitation and squeezing the abdomen of the nymphs, which permitted obtaining quickly almost 100% of the inoculate with loads between 1.9 and 8.9 × 106 trypomastigotes/nymph. The number of parasites per nymph and morphological changes were determined using phase microscopy with Giemsa staining. The nymphs ingested 7.4 times their weight of the infecting solution with volumes between 101 e 357 µL (229 ± 66 mg); 50% of the ingest was eliminated as urine during the first 24 hours. The trypomastigotes transformed to rounded forms before evolving into epimastigotes following different kinetics according to the isolate. This method is proposed for rapid, quantitative study of the early events of epimastigogenesis for T. cruzi in vivo.