Comparative study of the biological behaviour in hamster of two isolates of leishmania characterized respectively as L. major-like and L. donovani

Hamster inoculated intraperitoneally with 1 x 10(7) parasites of L. donovani and L. major-like of the New World were studied in groups of 15, 30, 60 and 90 days of infection. The parasite load and density showed progressive increase with the evolution of the infection and was higher in the L. donovani groups than in the L. major-like groups. The L. major-like groups showed parasite density higher in the spleen than in the liver and was similar in both organs in L. donovani groups. The histopathology showed a diffuse marked hyperplasia and hypertrophy of the reticuloendothelial system with high parasitism in the L. donovani groups while there was focal involvement of these organs in L. major-like groups, forming nodules of macrophages that were scantly parasitised. The biological behaviour could be useful in the preliminary studies of Leishmania strain in regional laboratories and understanding the histopathology of lesions caused by different leishmania species.

Immunoelectrophoretic study on common antigens of São Lourenço da Mata and Belo Horizonte strains of Schistosoma mansoni adult worms and Biomphalaria snails

Immunoelectrophoretic studies on common antigens were carried out by using rabbits sera immunized against São Lourenço da Mata and Belo Horizonte strains of Schistosoma mansoni adult worms and antigens of Biomphalaria glabrata pigmented (Jaboatão - PE); B. glabrata albino (Belo Horizonte - MG) and B. straminea (São Lourenço da Mata, PE). Furthermore, the reverse approach was proceeded, namely, sera anti Biomphalaria snails produced in rabbits were tested against both strains of Schistosoma adult worm antigens. The analysis of the common antigens between the SLM strains of S. mansoni adult worm and B. glabrata pigmented showed 8 to 9 precipitin bands, 3 bands with B. glabrata albino and only 1 band with B. straminea crude extracts. On the other hand, the BH strain of S. mansoni adult worm antisera produced 6 to 7 bands with B. glabrata pigmented, 5 bands with B. glabrata albino and 1 band with B. straminea antigenic extract. Biomphalaria snails crude extracts were fractionated by Sephadex G-100 column and three fractions were collected from each snail strain. The fractions were tested with anti SLM and BH strains of S. mansoni adult worm sera by immunoelectrophoresis. The common antigens fractionated from Biomphalaria snails crude extracts and those found for both strains of S. mansoni adult worm mostly existed in the first fraction and they were estimated to have molecular weight over 158,000 daltons. In our laboratory, it was found a relationship between the antigenic similarities and experimental infection rates of S. mansoni towards Biomphalaria snails so that more bands were seen with increasing infection rates of S. mansoni.

Evidences against a significant role of Mus musculus as natural host for Angiostrongylus costaricensis

Wild rodents have been described as the most important hosts for Angiostrongylus costaricensis in Central America and southern Brazil. Sinantropic rodents apparently do not play a significant role as natural hosts. A search for natural infection failed to document worms in 14 mice captured in the house of a patient with diagnosis of abdominal angiostrongylosis and experimental infection of a "wild" Mus musculus strain and groups of albino Swiss mice were carried out. Mortality was not significantly different and varied from 42% to 80% for Swiss mice and from 26% to 80% for "wild" mice. The high mortality of a "wild" M. musculus infected with A. costaricensis was very similar to what is observed with most laboratory mice strains. These data may be taken as indications that M. musculus is not a well adapted host for A. costaricensis, although susceptibility was apparently higher with "wild" populations of M. musculus as compared to Swiss strain.

ASSESSMENT OF IVERMECTIN THERAPEUTIC EFFICACY ON THIRD-STAGE LARVAE OF Lagochilascaris minor IN MICE EXPERIMENTALLY INFECTED

In this study we evaluated the potential action of ivermectin on third-stage larvae, both at migratory and encysted phases, in mouse tissues after experimental infection with Lagochilascaris minor. Study groups I and II consisted of 120 mice that were orally administered 1,000 parasite eggs. In order to assess ivermectin action upon migratory larvae, group I (60 mice) was equally split in three subgroups, namely I-A, I-B, and I-C. On the 7th day after inoculation (DAI), each animal from the subgroup I-A was treated with 200 µg/Kg ivermectin while subgroup I-B was given 1,000 µg/Kg, both groups received a single subcutaneous dose. To assess the drug action on encysted larvae, group II was equally split in three subgroups, namely II-A, II-B, II-C. On the 45th DAI each animal was treated with ivermectin at 200 µg/Kg (subgroup II-A) and 1,000 µg/Kg (group II-B) with a single subcutaneous dose. Untreated animals of subgroups I-C and II-C were used as controls. On the 60th DAI all animals were submitted to larva search. At a dose of 1,000 µg/Kg the drug had 99.5% effectiveness on third-stage migratory larvae (subgroup I-B). Ivermectin efficacy was lower than 5% on third-stage encysted larvae for both doses as well as for migratory larvae treated with 200µg/Kg.

Survival of Trypanosoma cruzi in sugar cane used to prepare juice

Chagas disease can be transmitted to man by many different means, including contact with infected triatomine feces, blood transfusion, laboratory accidents, organ transplants, and congenital or oral routes. The latter mode has received considerable attention recently. In this assay, we evaluate the survival of Trypanosoma cruzi contaminating sugar cane used to prepare juice, as well as the viability and capacity for infection by the parasite after recovery. Thirty triatomines were contaminated with T. cruzi Y strain and 45 days later pieces of sugar cane were contaminated with the intestinal contents of the insects. The pieces were ground at different intervals after contamination (time = 0, 1, 4, 6, 12 and 24 hours) and the juice extracted and analyzed. Different methods were used to show T. cruzi in the juice: direct analysis, hematocrit tube centrifugation and QBC, and experimental inoculation in 47 female BALB/c mice (five control mice and seven mice for each interval examined (five inoculated orally and two intraperitoneally). Positive results were found using the direct analysis and QBC methods for juice prepared up to 12 hours after initial contamination. However, by the centrifugation technique, positivity was found only up to four hours after contamination of the sugar cane. Inoculated animals showed parasitemia during a 14 day observation period, demonstrating the high survival rate of T. cruzi in sugar cane.

Biological implications of the phenotypic plasticity in the Schistosoma mansoni - Nectomys squamipes model

The water-rat Nectomys squamipes is mostly important non-human host in schistosomiasis mansoni transmission in Brazil, due to its susceptibility, high abundance and water-contact pattern. During experimental infection of N. squamipes with Schistosoma mansoni, adult worms show phenotypic plasticity. This finding led us to investigate whether biological behavior is also affected. This was assessed comparing the biological characteristics of four S. mansoni strains: BE (State of Belém do Pará), CE (State of Pernambuco), CMO (State of Rio Grande do Norte) and SJ (State of São Paulo) using laboratory-bred N. squamipes. The infection was monitored by determination of the pre-patent period, fecal egg output, egg viability, intestinal egg count and, infectivity rate. No biological modification was observed in these parameters. Overall results highlight that N. squamipes was susceptible to several S. mansoni strains, suggesting that it might contribute to the maintenance of schistosomiasis mansoni in Brazil.

Melanoides tuberculata (Mollusca: Thiaridae) as an intermediate host of Centrocestus formosanus (Trematoda: Heterophyidae) in Brazil

Pleurolophocercous cercariae emerged from naturally infected Melanoides tuberculata from Minas Gerais State, Brazil, were used to perform experimental infection of laboratory-reared Poecilia reticulata. Mature metacercariae were obtained from the gills of fishes and force-fed to Mus musculus. The adult parasites which recovered from small intestines of mice were identified as Centrocestus formosanus. This is the first report of M. tuberculata as intermediate host of this heterophyid in Brazil.

Melanoides tuberculata as intermediate host of Philophthalmus gralli in Brazil

Melanoides tuberculata that naturally harbored trematode larvae were collected at the Pampulha dam, Belo Horizonte (Minas Gerais, Brazil), during malacological surveys conducted from 2006 to 2010. From 7,164 specimens of M. tuberculata collected, 25 (0.35%) were infected by cercariae, which have been morphologically characterized as belonging to the Megalurous group, genus Philophthalmus. Excysted metacercariae were used for successful experimental infection of Gallus gallus domesticus, and adult parasites recovered from the nictitating membranes of chickens were identified as Philophthalmus gralli. This is the first report of P. gralli in M. tuberculata in Brazil.

EFFICACY OF NITAZOXANIDE AGAINST Toxocara canis: LARVAL RECOVERY AND HUMORAL IMMUNE RESPONSE IN EXPERIMENTALLY INFECTED MICE

SUMMARY The efficacy of nitazoxanide (NTZ) against toxocariasis was investigated in an experimental murine model and results were compared to those obtained using mebendazole. Sixty male BALB/c mice, aged six to eight weeks-old, were divided into groups of 10 each; fifty were orally infected with 300 larvaed eggs of T. canisand grouped as follows, G I: infected untreated mice; G II: infected mice treated with MBZ (15 mg/kg/day) 10 days postinfection (dpi); G III: infected mice treated with NTZ (20 mg/kg/day) 10 dpi; G IV: infected mice treated with MBZ 60 dpi; G V: infected mice treated with NTZ 60 dpi; GVI: control group comprising uninfected mice. Mice were bled via retro-orbital plexus on four occasions between 30 and 120 dpi. Sera were processed using the ELISA technique to detect IgG anti- Toxocaraantibodies. At 120 dpi, mice were sacrificed for larval recovery in the CNS, liver, lungs, kidneys, eyes and carcass. Results showed similar levels of anti- ToxocaraIgG antibodies among mice infected but not submitted to treatment and groups treated with MBZ or NTZ, 10 and 60 dpi. Larval recovery showed similar values in groups treated with NTZ and MBZ 10 dpi. MBZ showed better efficacy 60 dpi, with a 72.6% reduction in the parasite load compared with NTZ, which showed only 46.5% reduction. We conclude that administration of these anthelmintics did not modify the humoral response in experimental infection by T. canis. No parasitological cure was observed with either drug; however, a greater reduction in parasite load was achieved following treatment with MBZ.

Schistosoma mansoni: on the possibility of Indian buffalo (Bubalus bubalis) being experimentally infected

Male Indian buffalo (Bubalus bubalis) calves were submitted to Schistosoma mansoni infection by percutaneous, oral and subcutaneous routes. No worms or eggs were found in four of the animals tested. Bubalus bubalis appears to be refractory for S. mansoni.

Treatment with benznidazole in association with immunosuppressive drugs in mice chronically infected with Trypanosoma cruzi: investigation into the possible development of neoplasias

Benznidazole is recommended in Brazil for the treatment of Trypanosoma cruzi infection in acute and early chronic phases of Chagas' disease. Observations by others have indicated a higher incidence of neoplasias in immunosuppressed patients, presenting Chagas' disease reactivation, submitted to treatment with benznidazole. In the present study, we investigated whether there is a potentiation in the generation of lymphomas in chronically infected mice, treated with immunosuppressive drugs and benznidazole. For this, 142 Swiss mice chronically infected with the 21 SF strain of T. cruzi and 72 normal Swiss mice were used. Both infected and normal mice were divided into experimental groups and submitted to one of the following treatment regimens: benznidazole alone; immunosuppressive drugs (azathioprine, betamethasone and cyclosporin); a combination of immunosuppressive drugs and benznidazole; and untreated controls. In the infected group treated with benznidazole, one mouse developed a non-Hodgkin's lymphoma. This finding has been interpreted as a spontaneous tumor of mice. The study of the chronically infected mice treated with the combination of immunosuppressive drugs and benznidazole demonstrated an absence of lymphomas or other neoplasias. These findings support the indication of benznidazole, as the drug of choice, for immunosuppressed patients that develop a reactivation of Chagas' disease.

Potentiality of Achatina fulica Bowdich, 1822 (Mollusca: Gastropoda) as intermediate host of the Angiostrongylus costaricensis Morera & Céspedes 1971

Samples of Achatina fulica were experimentally infected with Angiostrongylus costaricensis larvae, etiological agent of abdominal angiostrongyliasis, showing that A. fulica is susceptible to the parasite. Achatina fulica may be a risk to urbanization of abdominal angiostrongyliasis presumably due to its high proliferation, continuous dispersion and remarkable adaptation in several Brazilian towns.

O virus do mixoma no coelho do mato (Sylvilagus minenses), sua transmissão pelos Aedes scapularis e aegypti

The brazilian wild rabbit (Sylvilagus minensis) is sensible to the virus of the mixomatosis but the desease takes on it a mild character, lasts for long time and generally do not kill the animal. The tumors are generally smaller and less numerous than those of the domestic rabbit, but sometimes there were noted large and flat lesions (fig. 3). The natural infection of the wild rabbit may be quite common not only because many rabbits caught in the country were found to be immune as also because it was found among the animals caught in the country near Rio, one that was infected with mixomatosis. The experimental infection of the Sylvilagus may be easily obtained by cutan, subcutan or conjuntival way and also when a health wild rabbit is placed in the same cage with a sick domestic animal. It is also possible to obtain the infection of the wild and domestic rabbits by the bite of infected blood sucking insects as fleas and mosquitoes. The infected mosquito can transmit the disease 2 or 3 times til 17 days after an infective meal on a sick rabbit. The transmission is a mecanical one and only the proboscis of the insect contains the virus as it was shown by the inoculation of emulsions of the proboscis, thorax and abdomen of the mosquito. Though mecanical this kind of transmission acts as an important epidemiological mean of dissemination of the deseasse and splains the suddendly outbreaks of mixomatosis in rabbits breedings where no new rabbits were introduced since very long time. The transmition of mixomatosis by fleas (Slenopsylla) was at first demonstrated by us, then S. Torres pointed out the capacity of Culex fatigans to transmit the desease and now we have proved that Aedes scapularis and Aedes aegypti were also able to transmit it (Foto 1 and 2). The virus of the mixomatosis (Chlamidozoon mixoma) is seen on the smeavs of the tumors of the wild reabbit with the same morphology, as in the material of the domestic animal.

A survey of planorbid molluscs in the Amazonian region of Brazil

A survey of the plarnorbid fauna in the Brazilian states of the Amazonian river basin revealed the occurence of 14 species, 8 of the genus Biomphalaria, 4 of Drepanotrema, 1 of Antillorbis and 1 of Plesiophysa, besides a naturalized puopulation of Helisoma duryi at Santa Rosa, municipality of Formosa, state of Goiás. The following is the distribution of the species by genera, in decreasing order of frequency (number of localities in parenthesis): 1. Biomphalaria straminea (50): Acre, Amazonas, Distrito Federal, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Pará and Roraima; 2. B. occidentalis (30): Acre, Amazonas, Mato Grosso and Mato Grosso do Sul; 3. B. schrammi (22); Distrito Federal, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul and Pará; 4. B. amazonica (14): Acre, Amazonas and Rondônia; 5. B. glabrata (13): Distrito Federal, Goiás, Maranhão and Pará; 6. B. peregrina (4): Distrito Federal, Goiás and Mato Grosso do Sul; 7. B. tenagophila (2): Distrito Federal and Goiás; 8. B. oligoza (2): Mato Grosso do Sul; 9. Drepanotrema lucidium (72): Acre, Amapá, Amazonas, Distrito Federal, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul, Pará, Rondônia and Roraima; 10. D. anatinum (41): Acre, Amazonas, Distrito Federal, Goiás, Maranhão, Mato Grosso do Sul, Pará, Rondônia and Roraima; 11. D. depressissimum (19): Acre, Amazonas, Distrito Federal, Goiás, Maranhão, Mato Grosso, Mato Grosso do Sul and Pará; 12. D. cimex (15): Acre, Amazonas, Distrito Federal, Goiás, Mato Grosso, Mato Grosso do Sul and Pará; 13. Antillorbis nordestensis (3): Distrito Federal, Maranhão and Pará; 14. Plesiophysa ornata (1): Goiás. B. glabrata is responsibel for transmission of schistosomiasis mansoni in northeastern Pará, northern Marnhão and central Goiás including the Distrito Fedreal. B. tenagophila, although susceptible to experimental infection with Schistosoma mansoni, has not been found naturally infected so far in the area. B. straminea has been incriminated as...

Quantification of Trypanosoma cruzi in the heart, lymph nodes and liver of experimentally inffected mice, using limiting dilution analysis

Limiting dilution analysis was used to quantify Trypanosoma cruzi in the lymph nodes, liver and heart of Swiss and C57 B1/10 mice. The results showed that, in Swiss and B1/10 mice infected with T. cruzi Y strain, the number of parasites/mg of tissue increased during the course of the infection in both types of mice, although a grater number of parasites were observed in heart tissue from Swiss mice than from B1/10. With regard to liver tissue, it was observed that the parasite load in the initial phase of infection was higher than in heart. In experiments using T. cruzi Colombian strain, the parasite load in the heart of Swiss and B1/10 mice increased relatively slowly, although high levels of parasitization were nonetheless observable by the end of the infection. As for the liver and lymph nodes, the concentration of parasites was lower over the entire course of infection than in heart. Both strains thus maintained their characteristic tissue tropisms. The limiting dilution assay (LDA) proved to be an appropriate method for more precise quantification of T. cruzi, comparing favorably with other direct microscopic methods that only give approximate scores.