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Snails infected by trematodes may increase or decrease their reproductive activity in response to the presence of infection. Our aim was to verify the reproductive alterations in Subulina octona after infection by Paratanaisia bragai. The infected snails were individually exposed for 24 hours to 20 parasite eggs and four groups were formed (10, 20, 30 and 40 d.p.i.- days after infection), along with control groups. Every 10 days, the number of eggs in the reproductive tract, number of eggs hatched, galactogen content and histopathological changes were evaluated. The reproductive in the control and infected snails presented an alternating pattern, where periods of high production of eggs and newly hatched were followed by periods of low production. However, in relation to the amount of galactogen, both control and infected groups followed the same pattern of variation. In the histology, we observed the presence of male and female gametes with marked reduction in the number of oocytes. The results indicate that the intra-snail development of the parasite affects the reproductive biology of the host. Resumo Moluscos infectados por trematódeos podem aumentar ou diminuir sua atividade reprodutiva em resposta à presença da infecção. Nosso objetivo foi verificar as alterações reprodutivas de Subulina octona após a infecção por Paratanaisia bragai. Os moluscos infectados foram individualmente expostos durante 24 horas a 20 ovos do parasito e quatro grupos foram formados (10, 20, 30 e 40 d.p.i. – dias pós infecção), com respectivos grupos controle. A cada 10 dias, o número de ovos no trato reprodutivo, o número de ovos eclodidos, o conteúdo de galactogênio e alterações histopatológicas eram avaliadas. O padrão reprodutivo nos moluscos controle e infectados evidenciou um comportamento alternante, nos quais períodos de alta produção de ovos e filhotes foram seguidos por períodos de baixa produção. No entanto, em relação ao conteúdo de galactogênio, moluscos controle e infectados seguiram o mesmo padrão de variação. Na histologia, observamos a presença de gametas masculinos e femininos com acentuada redução no número de óocitos. Os resultados indicam que o desenvolvimento intramolusco do parasito afeta a biologia reprodutiva do hospedeiro.

O gastropode Biomphalaria glabrata presente em grande parte do territorio nacional, atua como principal hospedeiro intermediario do trematodeo, Schistosoma mansoni , causador da esquistossomose no Brasil. O nematoide entomopatogenico (NEP) Heterorhabditis associado com a bacteria, Photorhabdus luminescens, e usado mundialmente no controle biologico de diversos organismos. Porem, nada se conhece sobre a susceptibilidade de B. glabrata a NEPs. Nesse estudo, alem de demonstrar a susceptibilidade do molusco ao nematoide, tambem avaliamos as alteracoes induzidas por Heterorhabditis bacteriophora em seu metabolismo glicemico. Pra tanto, seis grupos foram formados: tres grupos controle, constituido por organismos nao expostos ao nematoide, e tres grupos infectados, que foram expostos as formas infectantes do NEP. O experimento foi realizado em duplicata, utilizando um total de 240 molucos. Significativas alteracoes no metabolismo de carboidratos de B. glabrata foram observadas apos 3 semanas de infeccao. Os resultados indicam diminuicao dos niveis de glicose hemolinfatica, bem como nos conteudos de glicogenio estocados na glândula digestiva e glândula de albumen do caramujo. Em paralelo, os grupos infectados tambem apresentaram aumento na atividade da enzima lactato desidrogenase (LDH), indicando que a infeccao induz a ativacao de vias fermentativas do molusco. Apesar da ausencia de letalidade dos grupos expostos, a infeccao gerou comprometimento no metabolismo glicidico de B. glabrata , sobretudo, nas reservas de galactogenio, sugerindo potencial aplicabilidade em programas de controle biologico do gastropode.

The trematode Schistosoma mansoni is a heteroxenous parasite, meaning that during its life cycle needs the participation of obligatory intermediate and definitive hosts. The larval development occurs in aquatic molluscs belonging to the Biomphalaria genus, leading to the formation of cercariae, which emerge to infect the final vertebrate host. For this reason, studies for control of the diseases caused by digenetic trematodes often focus on combating the snail hosts. Thus, the objective of this study was to evaluate the susceptibility of Biomphalaria tenagophila embryos to the fungus Pochonia chlamydosporia (isolate Pc-10) under laboratory conditions. Two experimental groups were formed: the control group, consisting of egg masses not exposed to the fungus; and the treated group, in which the snail egg masses were exposed to mycelium of the fungal isolate (Pc-10). At the end of 15 days, the egg masses were evaluated under a stereomicroscope to analyze the hatching of B. tenagophila embryos in both experimental groups. The entire experiment was conducted in duplicate, with five replicates for each repetition (five egg masses/replicate), utilizing a total of 100 egg masses, with 20 to 30 eggs/egg mass. After 15 days of interaction, the exposure to the fungal hyphae bodies significantly impaired the viability of the B. tenagophila eggs, inhibiting the embryogenesis process by 83.7% in relation to the control group. Transmission and scanning electron microscopic images revealed relevant structural alterations in the egg masses exposed to the hyphae action of the fungus, interfering in the development and hatching of the young snails under analysis. These results indicate the susceptibility of B. tenagophila embryos to the fungus P. chlamydosporia (isolate Pc-10) and suggests the potential of Pc-10 to be used in the control of parasitic agents, such as S. mansoni, but in vivo experiments become necessary.

Angiostrongylus cantonensis is a metastrongylid nematode that has a heteroxenous cycle, where snails act as intermediate hosts and the rodents Rattus rattus and Rattus novergicus are the definitive hosts. However, humans may act as accidental hosts presenting an atypical form of parasitism. This fact has motivated research to better understand systems of relationships involving A. cantonensis, targeting the control of species of gastropods that act as intermediary hosts. For this, six groups were formed: three control groups (uninfected) and three infected groups, exposed to approximately 1200 L1 larvae of A. cantonensis. At the end of each week (1, 2, and 3 weeks), snails were dissected without anesthesia and the gonad–digestive gland (DGG) complex was separated for determination of oxygen consumption through high-resolution titration-injection respirometer (Oroboros, Oxygraph; Innsbruck, Austria). The results indicate suppression of mitochondrial oxidative metabolism of the host and compromised in different mitochondrial respiratory states. This effect, mainly observed in the group exposed to 1 week of infection, showed a decrease of approximately 38% (2.78 ± 0.37 pmol O2/mg of tissue; P

The snail Pseudosuccinea columella participates in the distribution of Fasciola hepatica in the environment by acting as its intermediate host. Therefore, the control of this lymnaeid is one of the ways to prevent hepatic fascioliasis. The objective of this study was to evaluate the susceptibility of P. columella to infective juveniles (IJs) of the entomopathogenic nematode (EPN) Heterorhabditis baujardi in laboratory conditions, as well as to investigate aspects related to the biochemistry and histopathology of snails exposed or not to the EPNs during three weeks. The EPN exposure induced significant reductions in the concentrations of glucose, total proteins and glycogen (gonad-digestive gland complex) in the snails during the onset of the infection, with the levels being restored as the infection progresses. These alterations were accompanied by increased hemolymph activities of aminotransferases and lactate dehydrogenase, as well as the concentrations of uric acid after the first and second weeks of the experiment. The histopathological analyses of the exposed snails revealed cell necrosis at the end of the first week, tissue inflammatory reactions one and two weeks after exposure, and degeneration three weeks afterward in comparison with the unexposed snails. Finally, scanning electronic microscopy revealed proliferation of fibrous connective tissue three weeks after exposure. The results indicate that P. columella is susceptible to H. baujardi. The exposure favored the establishment of a negative energy balance, increased the activity of enzymes related to tissue damages and promoted accumulation of nitrogen compounds in the host snails. Additionally, was observed in P. columella exposed to the EPNs, significant tissue lesions, and demonstrated the strong pathogenic potential of H. baujardi, indicating its possible application for biological control of this snail.

Heterorhabditis bacteriophora is an entomopathogenic nematode (EPN) that is mutually associated with Photorhabdus luminescens, utilized globally for biological control of numerous organisms. Freshwater snails of the species Biomphalaria glabrata have been incriminated as the main intermediate hosts of Schistosoma mansoni in Brazil, but virtually nothing is known about the susceptibility of these gastropod to EPNs. Information in this respect is relevant for control of these intermediate hosts, and thus of the helminthiases they transmit. This paper for the first time reports the susceptibility of B. glabrata to infective juveniles of H. bacteriophora (isolate HP88) under laboratory conditions. For that purpose, six groups were formed: three Control groups (not exposed) and three Treated groups, in which the snails were exposed to 300 juveniles infecting the nematode over three weeks. The entire experiment was conducted in triplicate, using a total of 270 snails. Significant physiological alterations in B. glabrata were observed in response to the infection by H. bacteriophora HP88, characterized by decreased levels of hemolymphatic glucose as well as reduced contents of glycogen stored in the host's digestive gland. In parallel, the hemolymphatic activity of lactate dehydrogenase increased in the infected snails, indicating that the infection induces breakdown of carbohydrate homeostasis in B. glabrata. Additionally, all the reproductive parameters analyzed were reduced as a consequence of the infection. The results indicate the occurrence of the phenomenon of parasitic castration in the B. glabrata/H. bacteriophora HP88 interface, probably due to the depletion of galactogen in the parasitized organism. Although the infection did not cause lethality in the population of infected snails, H. bacteriophora HP88 compromised the reproductive performance of B. glabrata, suggesting its applicability in programs for biological control of this planorbid.

Eosinophilic meningoencephalitis is an endemic zoonosis in Southeast Asia and the Pacific Islands, but in recent years, new cases have been reported in various countries outside these regions, including Brazil, where it is considered an emerging disease. In this study, the effect of infection by the nematode Angiostrongylus cantonensis, one of the main etiologic agent of this disease, on the reproductive biology of the planorbid snails Biomphalaria straminea and B. tenagophila was investigated during the pre-patent period. Alterations in the reproductive biology of B. straminea and B. tenagophila were analyzed in laboratory-reared specimens infected by A. cantonensis during 21 days; the number of eggs, number of egg masses, number of eggs/mass, number of eggs/snail, viable eggs/snail, survival and galactogen content in the albumen gland were measured. The results indicated the occurrence of initial compensation in reproductive effort in both snail species, but at different moments in the pre-patent period. More specifically, a reduction of 46.53% in the eggs/egg mass ratio in infected B. straminea was observed, a reflection of a 50% decline in the concentration of galactogen contained in the albumen gland. Changes in this parameter were also noted in B. tenagophila, but only at the end of the study period, with a reduction of 15.49%. Histological analyses indicate that changes observed can be explained by the tissue damages caused by the migration and development of the larvae. These results shed more light on the host-parasite relationship and indicate the importance of studying reproductive aspects for efforts to control infected snails. Considering that terrestrial snails can also transmit eosinophilic meningitis (in addition to aquatic mollusks), the data obtained expand knowledge of this host-parasite relationship and provide support for programs to control this zoonosis.

The objective of this study was to identify thyroid hormones and to examine their putative site of synthesis in Achatina fulica snails. For this purpose, radioimmunoassays were performed for T3 and T4 before and after long starvation with or without hemolymph deproteinization. Sodium/iodide symporter activity in vivo was analyzed through 125I administration with and without KClO4 pretreatment. Only T4 was detected, and its concentration decreased due to starvation or deproteinization. However, high-performance liquid chromatography analysis also showed the presence of T2 and T3 apart from T4, but rT3 was not detected in the A. fulica hemolymph. The sodium/iodide symporter activity was greater in cerebral ganglia than digestive gland, but KClO4 treatment did not inhibit iodide uptake in any of the tissues analyzed. Altogether, our data confirm for the first time the presence of thyroid hormones in A. fulica snails and suggest their participation in the metabolism control in this species, although the putative site of hormone biosynthesis remains to be elucidated.

Snails of the species Pseudosuccinea columella are considered intermediate hosts of Fasciola hepatica, a digenetic trematode that infects bile ducts of ruminants and humans, causing economic damage and serious problems for public health. These gastropods inhabit ponds, have high reproductive capacity, and lay their egg masses in submerged substrates on pond edges where they are exposed to desiccation and microbes, including fungi, that may exert pathogenic effects on the snail and its embryos. This information is relevant for control of the intermediate host and therefore of fasciolosis. With the objective of evaluating ovicidal potential of Pochonia chlamydosporia (Pc-10 isolate), a nematophagous fungus used as antagonistic agent for a wide variety of helminths of medical and veterinary importance, on egg masses of P. columella, we compared a treated group, where the egg masses were exposed to Pc-10 for a period of 25 days, and a control group, in which there was no exposure to the fungus. The results indicated that the embryogenesis process was significantly inhibited (93.15%) by Pc-10, suggesting its applicability in biological control programs of lymnaeid snails. In addition, ultrastructure showed the occurrence of different types of interactions between the egg masses with the mycelia of Pc-10: type 1, biochemical effects by the adherence of hyphae; type 2, morphological alterations, but without hyphal penetration; and type 3, lytic effect, morphological damage caused by penetration of hyphae by the fungus, resulting in some important structural modifications, thus compromising the viability of the eggs. The results demonstrate the susceptibility of P. columella egg masses to an isolate of P. chlamydosporia under laboratory conditions, providing valuable information for the biological control of this intermediate host.

The effect of infection by Echinostoma paraensei on the mitochondrial physiology of Biomphalaria glabrata was investigated after exposure to 50 miracidia. The snails were dissected one, two, three and four weeks after infection for collection and mechanical permeabilization of the gonad-digestive gland (DGG) complex. The results obtained indicate that prepatent infection by this echinostomatid fluke significantly suppresses the phosphorylation state (respiratory state 3) and basal oxygen consumption of B. glabrata, demonstrating that the infection reduces the ability of the intermediate host to carry out aerobic oxidative reactions. Additionally, relevant variations related to the uncoupled mitochondrial (state 3u) of B. glabrata infected by E. paraensei were observed. Four weeks after exposure, a significant reduction in mitochondrial oxygen consumption after addition of ADP (3.68±0.26pmol O2/mg proteins) was observed in the infected snails in comparison with the respective control group (5.14±0.25). In the uncoupled state, the infected snails consumed about 62% less oxygen than the infected snails (7.87±0.84pmol O2/mg proteins) in the same period. These results demonstrate a reduction in oxidative decarboxylation rate of the tricarboxylic acid cycle and faster anaerobic degradation of carbohydrates in the infected snails. The possible mechanisms that explain this new metabolic condition in the infected organisms are discussed.

The interaction between intermediate snail hosts and helminths can cause metabolic changes in the former. The snails use their reserves for maintenance of their vital processes, by activating the internal defense system and repairing tissue damage, while also supplying necessary energy for the parasites' development. Our aims were to evaluate the lactate dehydrogenase activity and the glucose concentration in the hemolymph of Biomphalaria glabrata experimentally coinfected by Angiostrongylus cantonensis and Echinostoma paraensei. Besides these aspects, the glycogen content in the digestive gland complex and cephalopedal mass along with histochemical changes in parasitized snails were analyzed. The snails were divided in group A (infected by 1200 L1 of A. cantonensis), group E (infected by 20 E. paraensei miracidia), group A + E (co-infected with A. cantonensis first and after a week by E. paraensei), group E + A (co-infected with E. paraensei first and then by A. cantonensis) and control group (not infected). During four weeks after exposure, samples were collected for biochemical and histochemical analyses. In the infected snails, glucose levels and glycogen content in the digestive gland complex and cephalopedal mass were significantly lower, in contrast with an increase of lactate dehydrogenase activity. These results indicate that the intense energy demand resulting from the presence of parasites causes the host snail to accelerate the anaerobic degradation of carbohydrates to obtain energy, in an attempt to maintain homeostasis. Both parasites were observed in histochemical analysis to cause tissue damages in the snails. So, although the snails were able to sustain the coinfection, several metabolic and tissue changes occurred, mainly in those infected with E. paraensei and then with A. cantonensis.

Investigation of co-infection by different helminths in snails can provide essential information about the biology of parasites co-existence under natural conditions. This study aimed to investigate the reproductive and histological changes of Biomphalaria glabrata experimentally co-infected with Echinostoma paraensei and Angiostrongylus cantonensis. Five groups of snails i.e. uninfected, with single and double infections, either E. paraensei first (E + A) or A. cantonensis first (A + E) were followed; three times a week during four weeks the numbers of egg masses, eggs and hatched snails were counted. Histological analysis of the ovotestis and albumen gland was performed after four weeks. The number of egg masses/snail, eggs/snail and hatched snails showed significative differences comparing the control group to all infected groups, especially in group E + A, with the majority of values of parameters analyzed lower than 50% of those observed for control snails. In addition, the mortality was higher in the group E + A than to control group. The histological analysis showed that presence of both parasites in the reproductive organs was associated with tissue damages.

For the first time, alterations in the oxidative metabolism of Achatina fulica experimentally infected with different parasite loads of Angiostrongylus cantonensis were determined. For this, the hemolymph activities of lactate dehydrogenase (LDH) and hexokinase and the glucose concentrations in the hemolymph, as well as the polysaccharide reserves in the digestive gland and cephalopedal mass, were assessed. Additionally, the contents of some carboxylic acids in the hemolymph of infected and uninfected snails were determined by high-performance liquid chromatography (HPLC), permitting a better understanding of the alterations related to the host's oxidative metabolism. As the main results, activation of oxidative pathways, such as the glycolytic pathway, was demonstrated in response to the increase in the activity of hexokinase. This tendency was confirmed by the decrease in the contents of glucose in the hemolymph of parasitized snails, indicating that the infection by A. cantonensis alters the host's metabolism, and that these changes are strongly influenced by the parasite load. This metabolic scenario was accompanied by activation of the anaerobic fermentative metabolism, indicated not only by an increase in the activity of (LDH), but also by a reduction of the content of pyruvic acid and accumulation of lactic acid in the hemolymph of parasitized snails. In this circumstance, maintenance of the host's redox balance occurs through activation of the fermentative pathways, and LDH plays a central role in this process. Together, the results indicate that A. cantonensis infection induces activation of the anaerobic metabolism of A. fulica, characterized not only by the accumulation of lactic acid, but also by a reduction in the pyruvic acid and oxalic acid contents in the hemolymph of the infected snails.

The effect of experimental infection by different parasitic loads of Angiostrongylus cantonensis (Nematode, Metastrongylidae) on the activities of the aminotransferases and concentration of total proteins, uric acid and urea in the hemolymph of Achatina fulica (Mollusca, Gastropoda) were investigated. There was a significant decrease in the concentration of total proteins in the exposed snails to 5000 or more larvae. This change was accompanied by an increase in the concentrations of urea and uric acid in the hemolymph, suggesting a higher rate of deamination of the amino acids. Besides this, variations in the activities of the aminotransferases were also observed, with the highest values recorded in the groups exposed to greater parasite load. These results suggest an increase in the use of total proteins, since there was increased formation of nitrogenous catabolites, in conformity with an increase in the aminotransferase activities. Infection was verified by the fact that L3 larvae recovered from the snails was proportion to the exposure dose of L1 larvae. Histopathological results also indicated presence of an inflammatory cell infiltrate, favoring an increase of both transaminases.

This study elucidated for the first time, under laboratory conditions, the susceptibility of Lymnaea columella to infective juveniles of Heterorhabditis baujardi LPP7. Exposure to the nematodes induced an average mortality rate of 66.66% in the population of L. columella, with the highest values attained from the second week after exposure onward. In addition, all the reproductive parameters analyzed (total number of eggs, number of egg masses, number of eggs laid/snail, embryo hatching rate and content of galactogen stored in the albumen gland) changed as a result of the infection. The results indicate the occurrence of the phenomenon of parasitic castration in L. columella infected by H. baujardi LPP7, probably through depletion of energy reserves such as galactogen, necessary to meet the intense metabolic demands of the nematode's larval stages. Finally, histopathological analysis demonstrated an intense process of cell disorganization, characterized by the occurrence of granulomatous inflammatory reactions in tissues of exposed snails, induced by the spoliative action of the bacteria/nematode. The results suggest the use of H. baujardi LPP7 as an alternative for biological control of the population of this intermediate host, and thus of the diseases in whose epidemiological chain it participates, especially fasciolosis, in line with the recommendations of the World Health Organization (WHO).

Carbohydrate metabolism plays an important role in the physiology and maintenance of energy stores within living organisms. However, when organisms are exposed to adverse physiological conditions, such as during pathogenic infection, these organisms begin to use alternative substrates (proteins and lipids) for energy production. This paper studied the carbohydrate metabolism of Rhipicephalus microplus after infection with Beauveria bassiana and Metarhizium anisopliae. The parameters evaluated were glucose concentration, enzymatic activities of lactate dehydrogenase (LDH), alanine aminostransferase (ALT) and aspartate aminostransferase (AST), amounts of uric acid and urea in the hemolymph, and amount of glycogen in the fat body. The results showed changes in nitrogenous products, including an increase in the amount of urea detected 48 h after infection with both fungi. The enzymatic activities of LDH, ALT, and AST were increased after infection. The amount of glucose was increased 24 h after infection with B. bassiana and was reduced 48 h after infection with both fungi. The amount of glycogen in the fat body was reduced at different times of infection with both fungi. These results demonstrate, for the first time, the changes in carbohydrate metabolism of R. microplus after infection with M. anisopliae and B. bassiana and contribute to a better understanding of this host-parasite relationship. Together with knowledge of diseases that affect these ticks and their susceptibility to entomopathogens, an understanding of tick physiology will be necessary for the effective implementation of current biological control methods and will assist in the discovery of new methods to control this ectoparasite.

The effect of experimental exposure of Bradybaena similaris by Eurytrema coelomaticum on the cholesterol and triglycerides total levels circulating in the hemolymph and the neutral lipids in the digestive gland–gonad (DGG) complex of the host snail were studied. In this study, snails were dissected after one, two, and three months of infection to collect the hemolymph and DGG to measure the cholesterol and triacylglycerol levels in the hemolymph and neutral lipid fractions in the tissues. The results for the hemolymph showed that the infection by this trematode resulted in a significant decrease in the concentrations of triacylglycerol during all periods analyzed, as well as, increase in the levels of cholesterol observed after the second and third months of study. This decrease suggests the possible use of triacylglycerol by both parasite and host as alternative substrate in maintaining their energy metabolisms. In parallel, the increase in the contents of cholesterol results from a severe cellular disorganization in snail, especially DGG, as a consequence of the intense plastic processes showed by parasite. Additionally, changes in the neutral lipid profile in the DGG of the infected snails were observed, indicating the importance of these molecules for successful infection.

Eosinophilic meningitis caused by Angiostrongylus cantonensis is a zoonosis endemic to Southeast Asia and the Pacific islands. It is considered an emerging disease because it has been expanding both geographically and in terms of the range of hosts. In South America, the first cases were reported in Brazil and were attributed to eating infected snails. In this study, 70 adult females of Rattus norvegicus (Wistar) were used to evaluate hematology, blood gases, cardiac markers and lung histopathology changes caused by this parasite. Of them, 60 were individually infected by orogastric gavage with 100 L(3) larvae and 10 uninfected animals formed the control group. The results obtained demonstrate that infection caused by A. cantonensis in R. norvegicus promotes significant hematological changes induced in the vertebrate host, manifested mainly in the form of regenerative anemia, thrombocytopenia and eosinophilia. Additionally, histopathological changes in the lung parenchyma demonstrated in rodents reveal the occurrence of areas of necrosis and extensive fibrosis, being directly related to the development of cellular hypoxia and enzyme cardiac changes. This study can contribute to a better understanding of the relationship between A. cantonensis and R. norvegicus.

The activity of lactate dehydrogenase and the concentrations of glucose in the hemolymph and of glycogen in the digestive gland and cephalopedal mass of Biomphalaria glabrata experimentally infected with Angiostrongylus cantonensis were evaluated. Additionally, high performance liquid chromatography (HPLC) was used to determine the hemolymph concentrations of some carboxylic acids (oxalic, piruvic, lactic and succinic). After one, two and three weeks of infection, the snails were dissected to collect the hemolymph and separate the tissues. A significant reduction of the levels of glucose in the hemolymph was observed as of the first week of infection in relation to the control group. The lactate dehydrogenase activity of the infected group was significantly higher than the average of the control group. This increase was accompanied by a reduction of the levels of piruvic acid and an increase in the levels of lactic acid in the hemolymph of the parasited snails, confirming the acceleration of the anaerobic metabolism, necessary for the host to obtain energy and maintain its redox balance. In parallel, there was a decrease in the glycogen content of the storage tissues, with that reduction being significantly greater in the cephalopedal mass than the digestive gland, demonstrating that in this interaction system, the mobilization of glycogen was not sufficient to maintain and reestablish the normal glycemia of the infected snails.

Eosinophilic meningitis is a disease characterized by increased eosinophils in the cerebrospinal fluid (CSF), which is the most commonly caused by invasion of the central nervous system by helminths, as occurs in Angiostrongylus cantonensis infections. The rodent Rattus norvegicus is the definitive natural host and humans act as accidental hosts and can become infected by eating raw or undercooked snails or food contaminated with infective L3 larvae. Recently in Brazil there have been four cases of eosinophilic meningitis due to ingestion of infected Achatina fulica. To evaluate biochemical and histopathological changes caused by this parasite, R. norvegicus were experimentally infected with 100 L3 larvae of A. cantonensis. After the anesthetic procedure, serum from the rodents was collected from the inferior vena cava for evaluation of the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALKP), gamma-glutamyl transferase (GGT), total protein and its fractions. During the necropsy, the liver was collected and weighed. Then a 1-g fragment was extracted from the major lobe to quantify the hepatic glycogen and fragment remainder was taken from the same lobe and fixed in Milloning’s formalin for histopathological examination. Additionally, helminths were collected from the brain and lungs of the rodents. The activities of AST, ALT, ALKP and GGT in the serum and hepatic glycogen increased in response to infection, while the levels of globulin and total protein increased only in the eighth week of infection and there was a reduction in the levels of serum glucose. Albumin and bilirubin concentrations remained stable during the experiment. Infection with A. cantonensis caused metabolic and histopathological changes in the rodents. This study can contribute to a better understanding of the relationship between A. cantonensis and R. norvegicus.

The glucose content in the hemolymph and glycogen content in the digestive gland–gonad complex (DGG) and cephalopedal mass of Biomphalaria glabrata exposed to different parasite doses (5 and 50 miracidia) of Echinostoma paraensei as well as the activity of lactate dehydrogenase were evaluated. HPLC (high-performance liquid chromatography) analyses were also performed to determine the concentrations of four organic acids (oxalic, succinic, pyruvic and lactic) present in the hemolymph of infected and uninfected snails, to better understand the effect of infection on the host’s energetic/oxidative metabolism. The snails were dissected 1–4weeks after infection to collect the hemolymph and separate the tissues. There was alteration in the glycemia of the snails at both parasite doses, with a significant increase of glycemia from of the third week after infection in comparison to the control group. Changes were also observed in the lactate dehydrogenase activity, with increased activity as the infection progressed. In parallel, there was a decrease in the glycogen content in the storage tissues, with a markedly greater reduction in the digestive gland–gonad complex (larval development site) in comparison with the cephalopedal mass. Additionally, the infection by both miracidial doses resulted in an increase of oxalic and lactic acid levels, as well as in a decline of piruvic and succinic acid levels in B. glabrata, thus explaining the reduction of the oxidative decarboxylation rate in the tricarboxylic acid cycle and acceleration of the anaerobic degradation of carbohydrates in the snails, through lactic fermentation, which is essential to ensure energy supply and success of the infection.

Experimental infection of Biomphalaria glabrata by Angiostrongylus cantonensis induces significant changes in the concentrations of triacylglycerol and cholesterol in the hemolymph and of neutral lipids in the digestive gonad-gland (DGG) complex of the host snail. In this study, snails were dissected after 1, 2, and 3 weeks of infection to collect the hemolymph and DGG and to measure the levels of cholesterol and triacylglycerol in the hemolymph and neutral lipid fractions in the tissues. The results show that infection by this nematode resulted in a significant decrease in the concentrations of both cholesterol and triacylglycerol in the hemolymph of B. glabrata during the parasite's initial ontogenic development period. This reduction indicates the possible use of these molecules by both parasite and host not only as energy substrates but also as structural factors required during development of the parasite's larval stages. In parallel, changes in the neutral lipid profile in the DGG and lipase activity of the infected snails were observed, indicating the importance of these molecules for successful infection.

This study investigated the possible biological, biochemical and histological changes in Bradybaena similaris (Gastropoda: Pulmonata) infected by Heterorhabditis indica (Rhabditida: Heterorhabditidae), strain LPP1. Two groups of 16 snails were formed: the control group (unexposed) and the treated group, which was exposed for three weeks to infective juveniles (J3) of H. indica LPP1. The experiment was conducted in duplicate, using a total of 64 snails. After the exposure period, the snails were dissected to collect the hemolymph and tissues, for evaluation of the physiological changes caused by the infection. The number of eggs laid/snail and the viability of these eggs were also assessed as indicators of the reproductive activity of B. similaris. Intense glycogenolysis was accompanied by a significant reduction (p

The objective of this study was to assess the effect of the exposure to fluazuron on the activity of common pesticide detoxification enzyme groups in the cattle tick (Rhipicephalus microplus). Engorged females of a susceptible strain (POA) and a resistant strain (Jaguar) were exposed in vitro to fluazuron and their eggs and larvae were used to compare the activities of the general esterases, mixed-function oxidases (MFO) and glutathione-S-transferase (GST). The results showed significant elevation in MFO contents and esterases activity in the resistant strain when compared with the susceptible strain, in eggs and larvae respectively. In the POA strain, the MFO activity in eggs was down-regulated by fluazuron exposure. Based on these results, it can be concluded that different detoxification enzymes can act in distinct pathways depending on the tick's development stage, and may be related to fluazuron detoxification in resistant strains.

Rhipicephalus microplus is an important tick in tropical regions due to the high economic losses caused by its parasitism. Metarhizium anisopliae and Beauveria bassiana are well-known entomopathogenic fungi that can afflict R. microplus ticks. The development of new targets and strategies to control this parasite can be driven by studies of this tick's physiology. Recently, it was reported that when exposed to adverse physiological conditions, ticks can activate fermentative pathways, indicating transition from aerobic to anaerobic metabolism. Nevertheless, the precise mechanism by which entomopathogenic fungi influence R. microplus metabolism has not been clarified, limiting understanding of the tick-fungus association. Thus, the present study aimed to evaluate the effect of infection of ticks by M. anisopliae and B. bassiana on the amount of selected carboxylic acids present in the hemolymph, enabling increased understanding of changes previously reported. The results showed preservation in the concentrations of oxalic, lactic, and pyruvic acids in the hemolymph 24 and 48 h after dropping from cattle; while there were variations in the concentration of these carboxylic acids after infection of female ticks to M. anisopliae and B. bassiana. Significant increases were observed in the concentration of oxalic and lactic acids and significant reduction of pyruvic acid for both observation times (24 and 48 h) after infection by entomopathogenic fungi. These results indicate that B. bassiana and M. anisopliae infection alters the basal metabolism of R. microplus females, resulting in the activation of fermentative pathways.

Aiming to characterize the potential off-target effects of fluazuron on ticks, biochemical analyses were conducted to evaluate changes in the carbohydrate metabolism of Rhipicephalus (Boophilus) microplus ticks after exposure to fluazuron. Hemolymph and fat body were collected from female ticks before and after (4, 8 and 15 days) exposure to fluazuron. Spectrophotometric analyses were done to quantify glucose concentration and lactate dehydrogenase (LDH) activity in the hemolymph and the concentration of glycogen in the tick’s fat body. High Performance Liquid Chromatography (HPLC) was employed to determine the concentration of carboxylic acids in the hemolymph and to evaluate changes in intermediary metabolic processes requiring oxygen consumption. Increases in the levels of LDH activity and lactic acid concentration indicated that fluazuron enhanced fermentative metabolism in ticks. Exposure to fluazuron was also found to increase glucose concentrations in the hemolymph over time, although no significant differences were noted daily. In addition to expanding the body of knowledge about the mode of action of fluazuron, investigations into these mechanisms may also be useful in discovering new and as yet unexplored secondary effects. Resumo Com o objetivo de caracterizar os efeitos não-alvo da ação do fluazuron, foram realizados testes bioquímicos para analisar possíveis alterações no metabolismo de carboidratos em carrapatos Rhipicephalus (Boophilus) microplus após sua exposição ao composto. Foram coletados hemolinfa e corpo gorduroso de fêmeas ingurgitadas antes e após (4, 8 e 15 dias) a exposição ao fluazuron. Análises espectrofotométricas foram usadas para quantificar a concentração de glicose e a atividade da lactato desidrogenase (LDH) na hemolinfa e concentração de glicogênio no corpo gorduroso. Cromatografia Líquida de Alta Eficiência (CLAE) foi usada para determinação das concentrações de ácidos carboxílicos na hemolinfa e avaliar possíveis alterações em metabolismo intermediário em relação ao consumo de oxigênio. Aumento na atividade de LDH e concentração de ácido lático indicaram que o fluazuron pode regular o metabolismo fermentativo em carrapatos. A exposição ao fluazuron também aumentou a concentração de glicose na hemolinfa, apesar de não ter havido diferença significativa na comparação entre as médias no mesmo dia de avaliação. Além de aumentar o conhecimento sobre o modo de ação do fluazuron, investigações sobre tais mecanismos também são úteis no descobrimento de novos efeitos secundários ainda não explorados.

The calcium content in the hemolymph and shell of Biomphalaria glabrata (Say, 1818) was determined after exposure to different parasite burdens (5 and 50 miracidia) of Echinostoma paraensei (Lie and Basch, 1967). The snails were dissected 1, 2, 3, and 4weeks after infection to collect the hemolymph and shell. An increase in calcemia was observed in snails infected with both miracidial doses. A significant decrease in the calcium ions in the shell was observed, coinciding with the calcemia peak in the hemolymph. This indicates greater mobilization of calcium between the shell and hemolymph to regulate the calcium content in the body when the snail is exposed to stress conditions, as has also been observed in some other infected snail species. The results obtained indicate that in this model, the calcium metabolism depends on the miracidial dose used.

The effect of experimental exposure of Biomphalaria glabrata to different doses (5 and 50) of Echinostoma paraensei miracidia on the total levels of cholesterol and triglycerides circulating in the hemolymph and the neutral lipids in the digestive gland–gonad (DGG) complex were studied. The snails were dissected one, two, three and four weeks after infection to collect the hemolymph and DGG tissue, to measure the levels of cholesterol and triglycerides in the hemolymph and neutral lipids in the tissue. The results for the hemolymph showed a similar order of variation for both substrates tested in the first week after infection. The reduced levels of these lipids in the infected snails indicate intense use of these substrates both by the intermediate host and the parasite, suggesting its probable participation in the energy metabolism and structural construction of the developing larval stages. Alterations in the profile of neutral lipids in the DGG were also found. The results obtained indicate that in this model, the lipid metabolism depends on the miracidial dose used.

The effect of infection by Echinostoma paraensei on the activity of the enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the concentration of total proteins, uric acid and urea in the hemolymph of Biomphalaria glabrata were investigated after exposure to five or 50 miracidia. The biochemical concentrations were measured weekly until the end of the fourth week after exposure. There was a significant decrease in the concentrations of total proteins in the snails exposed both to five and 50 miracidia, as well as an increase in the nitrogenous products of excretion, ALT and AST activities. The higher ALT activity in the hemolymph of the snails after infection with 50 miracidia suggests highest energetic requirement in these snails in relation to snails exposed to five miracidia. The results also suggest an increase in the use of total proteins, since there was increased formation of nitrogenous catabolites, in conformity with an increase in the aminotransferase activities, frequently associated with tissue damages. This can be explained by damage due to penetration by the miracidia and subsequent development of intramolluscan sporocysts and rediae.

One of the species that causes avian malaria is Plasmodium juxtanucleare. It is commonly found in poultry, especially when the birds receive food free of coccidiostats. Since industrial and organic poultry breeding is increasing in the world and few studies have been conducted examining the clinical parameters of both healthy and infected birds, this work evaluated whether the infection caused by P. juxtanucleare in Gallus gallus provokes alterations in the birds’ hepatic profile. We analyzed the activity of ALT and AST and carried out histological analyses of liver sections of infected fowls by intracelomic inoculation with infected blood from a donor fowl with a parasite load of around 7%. The infected birds’ parasite load was evaluated during 45 days by means of blood smears. There was a positive correlation between the increase in parasite load and higher ALT activity in the infected fowls, but there was no significant variation of the AST activity between the control and infected groups, possibly because of the non-specificity of this enzyme as an indicator of hepatic lesion. The results show that infection caused by P. juxtanucleare in G. gallus provokes hepatic alterations, indicated by the increase in the ALT enzyme activity and by the inflammatory infiltrates found in the liver sections of the infected fowls.

Angiostrongylus cantonensis is considered the main agent responsible for human eosinophilic meningoencephalitis. This parasite has low specificity for mollusk hosts and it can also use aquatic snails as auxiliary hosts. Studies based on the metabolic profile of Biomphalaria spp. infected by A. cantonensis have been conducted to observe parasite-host interactions. In the present study, the glucose content in the hemolymph and glycogen content in the digestive gland and cephalopedal mass of Biomphalaria tenagophila and Biomphalaria straminea experimentally infected by A. cantonensis were evaluated, along with the activity of LDH. The snails were dissected from 6 to 21days after infection to collect the hemolymph and separate the tissues. Decreases of 96% and 6.4% in the glucose content triggered a transition from aerobic to anaerobic metabolism in the two infected snail species, B. straminea and B. tenagophila, respectively. That finding was confirmed by high-performance liquid chromatography. These results indicate that when infected, these snails are able to change their metabolic profile, suggesting a strategy to maintain their homeostatic balance.

Chinchilla lanigera e um roedor proveniente do Chile e sua domesticacao foi inicialmente estabelecida para fins comercias objetivada na producao de peles e carnes. Dentre as doencas parasitarias que acometem tais animais, as protozooses mostram-se mais prevalentes causando serios problemas clinicos e sanitarios. O objetivo do presente estudo foi verificar a ocorrencia de Giardia spp.,Eimeria spp., e Cryptosporidium spp. em chinchilas provenientes de uma criacao comercial localizada no municipio de Afonso Claudio, Espirito Santo, Brasil. Para isto, foram coletadas fezes de cem chinchilas sendo estas submetidas aos metodos de Faust para deteccao de cistos de Giardia spp., metodo de Sheather para visualizacao de oocistos esporulados de Eimeria spp.e ao metodo de coloracao de Ziehl-Neelsen, para deteccao de oocistos esporulados de Cryptosporidium spp. A frequencia de cada protozoose foi determinada a partir do quociente estabelecido entre o numero de casos positivos e numero total de animais e os resultados foram expressos como variacao percentual (%). As leituras obtidas de cada tecnica coproparasitologica foram realizadas em duplicata. Apos o processamento das amostras fecais, frequencias de infeccao de 38% (38/100) para Giardia spp., 19% (19/100) para Cryptosporidium spp. e de apenas 8% (8/100) para Eimeria spp. foram demonstradas. Apesar do parasitismo nenhum dos animais apresentaram sinais clinicos evidentes das infeccoes. Adicionalmente, houve associacao entre a positividade das infeccoes, a faixa etaria e o sexo dos animais analisados.

El diagnóstico de la infección por tremátodos se basa esencialmente en la observación microscópica de los huevos de parásitos en las heces, a través de técnicas cualitativas y cuantitativas. En este estudio, se investigó la eficacia y la sensibilidad de las técnicas de Kato- Katz y Hoffman que se utilizan para diagnosticar Echinostoma paraensei en hámsters infectados y no infectados en condiciones experimentales. El método de Hoffman mostró mayor sensibilidad y eficacia en comparación con el método de Kato-Katz para el diagnóstico de E. paraensei.

Heterorhabditis is a nematode found in the soil that is used as an important biological control agent against various organisms. However, few studies have been performed of its use against snails and the present study is the first to investigate the effect of experimental exposure of Bradybaena similaris to Heterorhabditis indica LPP1. Two groups of 16 snails were formed: the control group (not exposed) and the treatment, which was exposed for three weeks to infective juveniles (J3) of H. indica LPP1. The entire experiment was conducted in duplicate, using a total of 64 snails. After this period, the snails were dissected to collect the hemolymph to evaluate the possible physiological alterations, namely total proteins, uric acid and hemolymph urea, as well as the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as a result of the infection. The terrariums were analyzed on alternate days throughout the experiment to count the dead snails. Intense proteolysis was observed in the infected snails. An increase in the level of uric acid and reduction of the hemolymph urea content indicated that the infection by H. indica results in the inversion of the excretion pattern of the host snail. Variations in the aminotransferase activities were also observed, with the infected group presenting significantly higher values (p

Levels of calcium in the haemolymph and reserves in the shell of Biomphalaria glabrata experimentally infected by Angiostrongylus cantonensis were determined for the first time. At the same time, histochemical analyses of the digestive gland of infected and uninfected snails were performed to better understand the possible changes in metabolism of calcium in these organisms. After 1, 2 and 3 weeks of infection, the snails were dissected for collection of haemolymph and separation of tissues. The highest calcium concentrations in the haemolymph were found 2 weeks after infection, with a 39.61% increase in relation to the respective control group. However, there was a significant reduction in the concentration of this ion in the haemolymph of infected snails after 1 week of infection in relation to the uninfected specimens. In parallel, intense hypocalcification was shown in the shell of infected snails 1 and 2 weeks after infection, differing significantly in relation to the respective control groups. Morphological changes in the digestive gland of infected snails were also observed, confirming the role of this ion as an important element in the parasite encapsulation process.

This study showed for the first time changes in the reproductive biology of Biomphalaria glabrata experimentally infected with Angiostrongylus cantonensis. The values of all the parameters analyzed (total number of eggs, number of egg masses, number of eggs/mass, number of eggs/snail, percentage of viable eggs and galactogen content in albumen gland) changed with progressive infection. The results indicate the occurrence of partial parasitic castration of B. glabrata by A. cantonensis larvae, probably in response to the depletion of energy reserves, with no injuries to the gonadal tissues.

The egg-laying rate, number of egg masses, number of eggs/mass, number of eggs hatched/snail and egg viability of Biomphalaria glabrata exposed to different doses (5 and 50) of Echinostoma paraensei miracidia were analyzed as indicators of reproductive activity. Polystyrene plates were placed in aquariums containing the snails and every other day for four weeks after infection the plates were removed to count the number of egg masses and eggs laid. After this, the plates were numbered individually and placed in new aquariums free of snails and the egg masses were observed daily to determine the hatching rate. On average there was an increase in the parameters evaluated in the infected snails in relation to the controls (uninfected snails), except for egg viability, which was significantly lower in the groups infected with 50 miracidia. These findings indicate that when infected, this host snail is able to increase its reproductive activity, suggesting an ecological strategy to maintain the species.

The effect of infection by Angiostrongylus cantonensis on the activity of the enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the concentration of total proteins, uric acid and urea in the hemolymph of Biomphalaria glabrata were investigated. The snails were dissected after 1, 2 and 3weeks of infection to collect the hemolymph. The infection by A. cantonensis induced severe changes in the host snail’s metabolism, triggering physiological mechanisms to minimize the deleterious effects caused by the larvae. There was a significant decrease in the concentration of total proteins in the infected snails, which occurred gradually as the infection advanced. This change was accompanied by an increase in the concentrations of urea and a decrease in the levels of uric acid in the hemolymph, suggesting that in this model the infection induces proteolysis and inversion of the excretion pattern of the infected snails. Besides this, variations in the activities of the aminotransferases were observed, with significantly higher levels in the infected groups than in the control group. These results indicate an increase in the protein metabolism of the infected snails, since there was an increase in nitrogen catabolites such as urea.

The influence of different photophases (0, 6, 12, 18 and 24 hours) on the triglycerides and total cholesterol contents in the hemolymph of A. fulica was evaluated, since there is no information in the literature about the influence of this factor on lipids metabolism in mollusks. After 2 and 4 weeks of exposure the snails were dissected. The cholesterol content at the 2nd and 4th weeks post exposure only varied significantly in the groups exposed at 24 hours and 0 hour of photophase, respectively. Probably, such increase may be a result of a rise in cholesterol biosynthesis and/or remodelling of cell membranes. There were no significant differences among the content of triglycerides in the snails exposed to 6, 12, 18 and 24 hours of photophase during two weeks. The snails exposed to intermediate photophase (6 and 12 hours) had the triglycerides content increased, ranging over values near to those observed in the group exposed to 0 hour. Results showed that triglycerides metabolism in A. fulica are more influenced by photoperiod than cholesterol metabolism. A negative relation is maintained between the triglycerides content in the hemolymph and the different photophases, with lower mobilisation of triglycerides under shorter photophases. A influência de diferentes fotofases (0, 6, 12, 18 e 24 horas) sobre os conteúdos de triglicerídeos e de colesterol total na hemolinfa de A. fulica foi avaliada, uma vez que não há na literatura informações sobre a influência deste fator sobre o metabolismo de moluscos. Após 2 e 4 semanas de exposição, os moluscos foram dissecados. O conteúdo de colesterol até a 2ª e 4ª semanas pós exposição somente variou significativamente nos grupos expostos a 24 horas e 0 horas de fotofase, respectivamente. Provavelmente, tal aumento pode ser resultado de uma elevada biossíntese de colesterol e/ou remodelamento de membranas celulares. Não houve diferenças significativas entre o conteúdo de triglicerídeos nos moluscos expostos a 6, 12, 18 e 24 horas de fotofase até a segunda semana. Os moluscos expostos a fotofases intermediárias (6 e 12 horas) tiveram o conteúdo de triglicerídeos aumentados, levando seus valores próximo àqueles observados para o grupo exposto a 0 hora de fotofase. Isto mostra que o metabolismo de triglicerídeos em A. fulica é mais influenciado pelo fotoperíodo do que o metabolismo de colesterol. Uma relação negativa é mantida entre o conteúdo de triglicerídeos na hemolinfa e as diferentes fotofases, com menor mobilização de triglicerídeos sob fotofases curtas.

The effect of concurrent infection by Echinostoma paraensei and Angiostrongylus cantonensis on the activity of the enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the concentration of total proteins, uric acid and urea in the hemolymph of Biomphalaria glabrata were investigated. Additionally, histopathological studies were conducted to better understand the dynamics of ontogenic development of both helminths in the host and the possible biochemical effects. Co-infections by helminths and other parasites often occur due to the wide distribution of helminths and the chronic nature of the infection. The biochemical parameters were measured at the end of the seventh week after exposure. The co-infection resulted in a significant decrease in the total proteins concentration in the hemolymph of snails as well as an increase in the nitrogen excretion products, these results showed that the infection leads to exhaustion of free circulating and stored carbohydrates and the infected snails make use alternative substrates, such as free amino acids. So, the protein degradation to release free amino acids causes a decrease in the content of total proteins in the snail host and an amino acids deamination process, increasing the content of ammonium, which needs to be detoxified. This occurs by increasing the urea and uric acid contents. This observation is corroborated by the increase of ALT and AST activities, enzymes directly related to amino group from an amino acid to an α-ketoacid an important step to generate new carbon skeleton for glucose synthesis de novo, as well as new intermediates to the Krebs cycle. Additionally, reduction in the recovery of L3 from the co-infected group (A + E) was observed, since in this association the burden was higher than in the other. Histopathological results showed a change in the distribution of A. cantonensis in the presence of E. paraensei, indicating that the presence of this trematode impairs the dynamic transmission of A. cantonensis.

The South American water rat Nectomys squamipes is a wild mammal reservoir of Schistosoma mansoni in Brazil. In the present study, wild rodents were collected in the field and categorized into two groups: infected and uninfected by S. mansoni. Blood was collected to analyze changes in the serum glucose level (mg/dL) and liver fragments were used to determine the hepatic glycogen content (mg of glucose/g tissue). The histological examination showed inflammatory granulomatous lesions in different phases of development in the liver of rodents naturally infected with S. mansoni, in some cases with total or partial occlusion of the vascular lumen. Early lesions were characterized by the presence of inflammatory infiltrate around morphologically intact recently deposited eggs. Despite the significance of these histological lesions, the biochemical changes differed in extent. N. squamipes naturally infected byS. mansoni showed no variation in hepatic glycogen reserves. These findings were accompanied by a significant increase in plasma glucose contents, probably as a consequence of amino acids deamination, which are degraded, resulting in the formation of intermediates used as precursors for the glucose formation, without compromising the reserves of liver glycogen. In the wild, naturally infected N. squamipes can maintainS. mansoni infections without undergoing alterations in its carbohydrate metabolism, which minimizes the deleterious effects of S. mansoni.