Iara Tersia Freitas Macedo

Anthelmintic effect of Eucalyptus staigeriana essential oil against goat gastrointestinal nematodes.

The aim of this study was to evaluate the anthelmintic efficacy of Eucalyptus staigeriana essential oil (EsEO). The in vitro effects of EsEO were determined through the egg hatching test and the inhibition of larval development of Haemonchus contortus. The oil was subjected to acute and subacute toxicity rodents. The in vivo effects were determined through fecal egg count reduction test in goats. 1.35 and 5.4 mgml(-1) EsEO inhibited 99.27 and 99.20% H. contortus egg hatching and larval development. In subacute toxicity of EsEO, all parameters were found to be in the normal range, and histopathological analysis of organs did not present alterations. EsEO efficacy against goat gastrointestinal nematodes was 76.57% at 15th day after treatment. E. staigeriana essential oil showed in vitro and in vivo anthelmintic activity.

Anthelmintic activity of Cocos nucifera L. against sheep gastrointestinal nematodes

The development of anthelmintic resistance has made the search for alternatives to control gastrointestinal nematodes of small ruminants imperative. Among these alternatives are several medicinal plants traditionally used as anthelmintics. This work evaluated the efficacy of Cocos nucifera fruit on sheep gastrointestinal parasites. The ethyl acetate extract obtained from the liquid of green coconut husk fiber (LGCHF) was submitted to in vitro and in vivo tests. The in vitro assay was based on egg hatching (EHT) and larval development tests (LDT) with Haemonchus contortus. The concentrations tested in the EHT were 0.31, 0.62, 1.25, 2.5 and 5 mg ml(-1), while in the LDT they were 5, 10, 20, 40 and 80 mg ml(-1). The in vivo assay was a controlled test. In this experiment, 18 sheep infected with gastrointestinal nematodes were divided into three groups (n=6), with the following doses administered: G1-400 mg kg(-1) LGCHF ethyl acetate extract, G2-0.2 mg kg(-1) moxidectin (Cydectin) and G3-3% DMSO. The worm burden was analyzed. The results of the in vitro and in vivo tests were submitted to ANOVA and analyzed by the Tukey and Kruskal-Wallis tests, respectively. The extract efficacy in the EHT and LDT, at the highest concentrations tested, was 100% on egg hatching and 99.77% on larval development. The parameters evaluated in the controlled test were not statistically different, showing that despite the significant results of the in vitro tests, the LGCHF ethyl acetate extract showed no activity against sheep gastrointestinal nematodes.

Activity of chitosan-encapsulated Eucalyptus staigeriana essential oil on Haemonchus contortus

Phytotherapy has been described as an alternative method for the control of gastrointestinal nematodes in small ruminants. Goal of the encapsulation of essential oils in biopolymer matrices is to optimize the biological effects of these oils. The aim of the present study was to evaluate the in vitro and in vivo anthelmintic activity of encapsulated Eucalyptus staigeriana essential oil (EncEs) on the eggs and larvae of Haemonchus contortus. Therefore, the egg hatching test (EHT), larval development test (LDT) and worm load evaluation were performed to evaluate Meriones unguiculatus experimentally infected with H. contortus. The chemical constituents of E. staigeriana essential oil (EsEO) and the in vitro oil release profile from the chitosan matrix at a pH of 1.2 and 7.0 were also characterized. EncEs and EsEO inhibited larval hatching by 97.19% and 99.96% at doses of 1.5 and 1.0 mg ml(-1), respectively. In the LDT, EncEs and EsEO induced a larvicidal effect greater than 95% at concentrations of 5.8 and 8 mg ml(-1), respectively. EncEs and EsEO decreased H. contortus load in M. unguiculatus by 40.51% and 46.44%, respectively. The major chemical constituents of EsEO were (+)-Limonene (72.9%), 1,8-Cineole (9.5%) and o-Cimene (4.6%). The release profile of EsEO was 30% in acid and 25% at neutral pH. The similar efficacy of EncEs and EsEO demonstrates that there was no optimization of anthelmintic action following the encapsulation process. Therefore, the use of new encapsulation matrices with controlled release in the pH of the abomasum should be investigated.

Anthelmintic activity of Lippia sidoides essential oil on sheep gastrointestinal nematodes

Medicinal plants have been investigated for their anthelmintic properties and shown to be effective against eggs and larvae of gastrointestinal nematodes. The aim of this study was to evaluate the efficacy of the Lippia sidoides essential oil (LsEO) on sheep gastrointestinal nematodes. Initially, 44 naturally infected sheep were divided and treated with 200 microg kg(-1) ivermectin and 230 and 283 mg kg(-1) LsEO, respectively, plus the control. Fecal samples were collected from each animal to determine epg at 7, 14 and 21 days after treatment. In another test, 21 sheep were distributed and treated with 200 microg kg(-1) ivermectin, 283 mg kg(-1) LsEO and the control, respectively. Seven days after treatment, they were euthanized and necropsied to count and identify the nematodes from the abomasum, small and large intestines. In the first test, the efficacy of 230 and 283 mg kg(-1) LsEO and ivermectin was 38%, 45.9% and 40.2%, respectively, 7 days after treatment, and 30%, 54% and 39.6%, respectively, 14 days after treatment. In the second experiment, the respective efficacy of 283 mg kg(-1) LsEO and ivermectin was 56.9% and 34.4% against Haemonchus spp., and 39.3% and 63.6% against Trichostrongylus spp.

Effect of six tropical tanniferous plant extracts on larval exsheathment of Haemonchus contortus

Tanniferous plants represent a promising alternative for controlling gastrointestinal nematodes of small ruminants. This experiment evaluated the effects of extracts from the leaf and stem of Anadenanthera colubrina, Leucaena leucocephala and Mimosa tenuiflora on larval exsheathment of Haemonchus contortus in vitro and verified the role of tannins in this process. Third-stage larvae of H. contortus were incubated with extracts for 3 hours and were exposed to sodium hypochlorite solution. The extracts were tested at 300 μg.mL(-1) and accompanied by controls: phosphate buffer solution (PBS) and polyvinyl polypyrrolidone (PVPP). The larval exsheathment was evaluated for 60 minutes, and the results were subjected to the Kruskal-Wallis test (p < 0.05). The six extracts blocked larval exsheathment. After PVPP addition, a tannin inhibitor, the exsheathment percentage was similar to the PBS (p > 0.05), except for L. leucocephala and M. tenuiflora leaf extracts. However, pre-incubation with PVPP of these two extracts significantly changed larval exsheathment when compared to the non-treated extracts (p < 0.05). These results suggest that A. colubrina, L. leucocephala and M. tenuiflora could be useful in gastrointestinal nematode control and that tannins are probably the main compounds involved in the observed effects. However, in vivo and toxicological studies should be conducted.

Identification and quantification of benzimidazole resistance polymorphisms in Haemonchus contortus isolated in Northeastern Brazil.

Haemonchus contortus is the most prevalent nematode in Brazil. The objective of this study was to select 6 populations of H. contortus of known or suspected benzimidazole resistance status and characterize these using quantitative real-time polymerase chain reaction (qPCR) for single nucleotide polymorphisms (SNPs) F200Y, F167Y and E198A in the β-tubulin isotype 1 gene. qPCR was performed using DNA from a pool of 10 adult male H. contortus from a single animal per farm. Faecal egg count reduction test (FECRT) and egg hatch test (EHT) were used to determine the resistance status. Samples were obtained from 6 farms located in 5 counties in the Ceará State: Tauá, Boa Viagem, Quixadá, Santa Quitéria and Solonópole. The inbred-susceptible-Edinburgh (ISE) isolate was used as reference for comparative purposes in the qPCR. Benzimidazole resistance was detected by FECRT on all farms with efficacy values ranging from 0 to 51%. EC50 values as determined by EHT were all above 1.49μg/ml. High frequencies of the resistant SNPs F200Y and F167Y alleles were detected but no resistance was detected at SNP E198A. Our results suggest that the SNPs F167Y and F200Y are both important for benzimidazole resistance in the studied populations.

In vitro activity of Lantana camara, Alpinia zerumbet, Mentha villosa and Tagetes minuta decoctions on Haemonchus contortus eggs and larvae

The resistance of gastrointestinal nematodes to anthelmintics has increased the need to evaluate natural products that can replace or assist current strategies to control gastrointestinal nematodes. The objective of this study was to evaluate the effect of decoctions of Lantana camara (DLc), Alpinia zerumbet (DAz), Mentha villosa (DMv) and Tagetes minuta (DTm) on Haemonchus contortus by two in vitro tests. The effects of increasing concentrations of lyophilized decoctions (0.31 to 10mg/ml) were assessed using the egg hatch test (EHT). The decoctions were then tested in the larval artificial exsheathment assay. H. contortus third stage larvae (L3) were exposed to 0.31 mg/ml A. zerumbet and M. villosa decoctions and 0.62 mg/ml T. minuta and L. camara decoctions for 3h and then exsheathment procedure at 10 min intervals. An inhibitor of tannins, polyvinyl polypyrrolidone (PVPP), was used to study if tannins were responsible for the inhibitory effect on hatching and exsheathment of larvae. A. zerumbet, M. villosa and T. minuta showed a dose-dependent effect in the EHT, which did not disappear after the addition of PVPP. No effect was observed for L. camara in the EHT. However, the decoctions inhibited the process of larval exsheathment, which may be related to tannin action because the addition of PVPP reversed the inhibitory effect. A. zerumbet, M. villosa and T. minuta decoctions showed inhibitory activity on H. contortus larvae hatching and exsheathing. The decoctions of these plants could be used to control gastrointestinal nematodes following confirmation of their anthelmintic activity in vivo.

Comparative efficacy and toxic effects of carvacryl acetate and carvacrol on sheep gastrointestinal nematodes and mice

Carvacrol is a compound isolated from some essential oils. It has been reported to possess anthelmintic activity. Acetylation of this monoterpene has been proposed as a potential way to reduce the toxicity and enhance the pharmacological effects of carvacrol. This study aimed to evaluate the effect of carvacryl acetate (CA) using in vitro and in vivo assays with gastrointestinal nematodes of small ruminants. The egg hatching test (EHT), larval development test (LDT) and adult worm motility (AWM) assessment were conducted to evaluate the effect of the acetylated product and pure carvacrol on Haemonchus contortus eggs, larvae and adults. The structural changes induced in adult H. contortus were assessed using scanning electron microscopy (SEM). CA and carvacrol acute toxicity was evaluated in mice. Finally, the efficacy of 250 mg/kg CA and 2.5mg/kg monepantel (positive control) were evaluated in 30 sheep naturally infected with gastrointestinal nematodes by the fecal egg count reduction test (FECRT). In vitro tests were analyzed by analysis of variance (ANOVA) followed by comparison with Tukeys test. The efficacy was calculated by the Boot Street program using the arithmetic average. The number of eggs in feces (epg) of the groups were transformed to log (x+1) and subjected to ANOVA to compare differences among the groups by Tukeys test. The level of significance was P<0.05. CA and carvacrol inhibited larval hatching by 89.3 and 97.7% at doses of 8.0 and 1.0mg/ml, respectively. At the concentration of 2mg/ml, CA and carvacrol inhibited 100% of larval development. At a concentration of 200 μg/ml, CA and carvacrol inhibited the motility of adult worms by 100% and 58.3% at 24h post-exposure, respectively. CA caused cuticle and vulvar flap wrinkling and bubbles to emerge from the tegument. Carvacrol caused more discreet effects on the cuticle and vulvar flap. The LD10 and LD50 of CA were 566.7 mg/kg and 1544.5mg/kg, respectively. The LD10 and LD50 of carvacrol were 546.8 mg/kg and 919 mg/kg, respectively. CA and monepantel reduced the epg of sheep by 65.9 and 96.4%, respectively, at 16 days post-treatment. CA showed in vitro and in vivo anthelmintic activity and was less toxic than carvacrol.

Efficacy of free and nanoencapsulated Eucalyptus citriodora essential oils on sheep gastrointestinal nematodes and toxicity for mice.

Herbal medicines with anthelmintic effects are alternatives for the sustainable control and prevention of disease caused by gastrointestinal parasites. The nanoencapsulation of essential oils has been proposed to enhance the absorption of their constituents and improve their efficacy. The present study aimed to evaluate the efficacy of free and nanoencapsulated Eucalyptus citriodora essential oil (EcEO) on the control of gastrointestinal nematodes of small ruminants in vitro and in vivo. Chitosan was used as a matrix for the formulation of a nanoemulsion. Chromatographic and physico-chemical analyses of EcEO were performed. Egg hatch (EHT) and larval development (LDT) tests were conducted to evaluate the effectiveness of nanoencapsulated and free EcEO on the eggs and larvae of Haemonchus contortus. Acute toxicity of free and nanoencapsulated EcEO was evaluated using mice. Finally, nanoencapsulated EcEO efficacy on the control of gastrointestinal nematodes was calculated by fecal egg count reduction test (FECRT) treating 30 sheep naturally infected with 250 mg/kg of free and nanoencapsulated EcEO. In vitro tests were analyzed by an analysis of variance (ANOVA) followed by comparison with the Tukey test. The efficacy of FECRT was calculated by the BootStreet program through arithmetic average, using the formula 100 (1-XT/XC). To compare the differences between epg, the data were transformed to log(x+1) and subjected to an ANOVA to compare the significant differences between groups by Tukeys. The level of significance was P<0.05. The free (4 mg/ml concentration) and nanoencapsulated (2mg/ml concentration) EcEO inhibited larvae hatching by 97.2% and 92.8%, respectively. Free and nanoencapsulated EcEO at 8 mg/ml inhibited larval development by 99.8% and 98.1%, respectively. In the acute toxicity test, the LD10 and LD50 of free EcEO was 1999 and 2653 mg/kg, respectively, while the LD10 and LD50 of nanoencapsulated EcEO was 1121 and 1681 mg/kg, respectively. Nanoencapsulated and free EcEO reduced FEC similarly by 40.5% and 55.9%, respectively at 10 days post-treatment. Nanoencapsulated EcEO did not obtain the expected efficacy in vivo.

Monitoring of Lutzomyia longipalpis Lutz & Neiva, 1912 in an area of intense transmission of visceral leishmaniasis in Rio Grande do Norte, Northeast Brazil

Urban increase of visceral leishmaniasis (VL) in Brazil is associated with the adaptation of its vector, Lutzomyia longipalpis, to environments modified by humans. The present study reports the results of an entomological monitoring of L. longipalpis and the effect of environmental variables on its population density. Sandflies were captured in the municipality of Mossoró, State of Rio Grande do Norte, Northeastern Brazil, from January 2005 to December 2006. Two CDC light traps were placed monthly for four consecutive nights in the peridomicile of selected households. Data analysis was based on the chi-square test and linear regression. A total of 2,087 sandflies were captured, 99.86% of which were L. longipalpis. A higher proportion of females were captured (p < 0.05). Monthly analysis of the variables temperature, relative humidity and rainfall did not show a significant influence on population density. However, there were seasonal differences: approximately 70% of sand flies were captured during the rainy season (p < 0.05). The predominant species, L. longipalpis, is present in substantial number, representing a public health risk. Therefore, because of higher prevalence during the rainy season, we recommend intensified VL control measures before and during this season to reduce the risk of disease transmission.