Longitudinal clinical and serological survey of abdominal angiostrongyliasis in Guaporé, southern Brazil, from 1995 to 1999

Abdominal angiostrongyliasis is a zoonotic infection caused by Angiostrongylus costaricensis, a nematode with an intra-vascular location in the mesentery. Our objective was to address several aspects of the natural history of this parasitosis, in a longitudinal clinical and seroepidemiological study. A total of 179 individuals living in a rural area with active transmission in southern Brazil were followed for five years (1995-1999) resulting in yearly prevalence of 28.2%, 4.2%, 10%, 20.2% and 2.8% and incidences of 0%, 5.9%, 8% and 1.5%, respectively. Both men and woman were affected with higher frequencies at age 30-49 years. In 32 individuals serum samples were collected at all time points and IgG antibody reactivity detected by ELISA was variable and usually persisting not longer than one year. Some individual antibody patterns were suggestive of re-infection. There was no association with occurrence of abdominal pain or of other enteroparasites and there was no individual with a confirmed (histopathologic) diagnosis. Mollusks were found with infective third-stage larvae in some houses with an overall prevalence of 16% and a low parasitic burden. In conclusion, abdominal angiostrongyliasis in southern Brazil may be a frequent infection with low morbidity and a gradually decreasing serological reactivity.

Larvicidal activity of oil-resin fractions from the Brazilian medicinal plant Copaifera reticulata Ducke (Leguminosae-Caesalpinoideae) against Aedes aegypti (Diptera, Culicidae)

Oil-resin fractions from Copaifera reticulata Ducke (Leguminosae-Caesalpinoideae) were evaluated for larvicidal activity on third larval instars of Aedes aegypti, in searching for alternative control methods for this mosquito. The bioactive fractions were chemically monitored by thin-layer chromatography, ¹H and 13C nuclear magnetic resonance and mass spectrometry. Bioassays were performed using five repetitions, at a temperature of 28 ± 1°C, relative humidity of 80 ± 5% and light and dark cycles of 12h. Mortality was indicated by darkening of the cephalic capsule after 24h of exposure of the larvae to the solutions. The most active fractions were CRM1-4 (sesquiterpenes) and CRM5-7 (labdane diterpenes), which showed LC50 values of 0.2 and 0.8ppm, respectively.

Leaf extracts of Melia azedarach Linnaeus (Sapindales: Meliaceae) act as larvicide against Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae)

The objective of this study was to compare the larvicidal effect of hydroethanolic extracts of fresh and dry leaves of Melia azedarach Linnaeus (Sapindales: Meliaceae) on Aedes aegypti (Linnaeus, 1762) (Diptera: Culicidae). All the extracts evaluated induced mortality among the third and fourth instar larvae of Aedes aegypti after 24 and 48 hours of exposure to the products. Although previous studies had demonstrated the action of seeds and fruits of Melia azedarach against the larvae of different Aedes aegypti populations, the present report is the first to show the larvicidal effect of the fresh and dry leaves of this plant.

Ocular lesions in gerbils (Meriones unguiculatus) infected with low larval burden of Toxocara canis: observations using indirect binocular ophthalmoscopy

To study the frequency of ocular lesions in 30 gerbils infected with 100 embryonated eggs of Toxocara canis, indirect binocular ophthalmoscopy was performed 3, 10, 17, 24, 31 and 38 days after infection. All the animals presented larvae in the tissues and 80% presented ocular lesions. Hemorrhagic foci in the choroid and retina were present in 92% of the animals with ocular lesions. Retinal exudative lesions, vitreous lesions, vasculitis and retinal detachment were less frequent. Mobile larvae or larval tracks were observed in four (13.3%) animals. Histological examination confirmed the ophthalmoscopic observations, showing that the lesions were focal and sparse. In one animal, there was a larva in the retina, without inflammatory reaction around it. The results demonstrated that gerbils presented frequent ocular lesions after infection with Toxocara canis, even when infected with a small number of embryonated eggs. The lesions observed were focal, consisting mainly of hemorrhages with signs of reabsorption or inflammation in different segments of eye, and differing from the granulomatous lesions described in ocular larva migrans in humans.

Chemical composition, toxicity and larvicidal and antifungal activities of Persea americana (avocado) seed extracts

The present study had the aim of testing the hexane and methanol extracts of avocado seeds, in order to determine their toxicity towards Artemia salina, evaluate their larvicidal activity towards Aedes aegypti and investigate their in vitro antifungal potential against strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis through the microdilution technique. In toxicity tests on Artemia salina, the hexane and methanol extracts from avocado seeds showed LC50 values of 2.37 and 24.13mg mL-1 respectively. Against Aedes aegypti larvae, the LC50 results obtained were 16.7mg mL-1 for hexane extract and 8.87mg mL-1 for methanol extract from avocado seeds. The extracts tested were also active against all the yeast strains tested in vitro, with differing results such that the minimum inhibitory concentration of the hexane extract ranged from 0.625 to 1.25mg L-¹, from 0.312 to 0.625mg mL-1 and from 0.031 to 0.625mg mL-1, for the strains of Candida spp, Cryptococcus neoformans and Malassezia pachydermatis, respectively. The minimal inhibitory concentration for the methanol extract ranged from 0.125 to 0.625mg mL-1, from 0.08 to 0.156mg mL-1 and from 0.312 to 0.625mg mL-1, for the strains of Candida spp., Cryptococcus neoformans and Malassezia pachydermatis, respectively.

Lagochilascaris minor: antibody production in experimentally infected mice

Lagochilascaris minor is the causative agent of lagochilascariosis, a disease that affects the neck region and causes festering abscesses, with eggs, adult parasites and L3/L4 larvae within the purulent exudates. Today, mice are considered to be intermediate hosts for the parasite. C57BL/6 mice produce immunoglobulin IgM, IgA and IgG against the crude extract of the parasite; on the other hand, antibodies produced against the secreted/excreted antigens of Lagochilascaris minor present lower levels of IgM, IgA and IgG. This is the first description of antibody detection against different antigens of Lagochilascaris minor.

Experimental lagochilascariosis in X-chromosome-linked immunodeficient mice

Lagochilascaris minor is the etiological agent of lagochilascariosis, a disease that affects the neck region and causes exudative abscesses, with eggs, adult parasites and L3/L4 larvae in the purulent exudates. Mice are now considered to be intermediate hosts for the parasite. To determine the pattern of infection in B1 cell-deficient mice, experimental lagochilascariosis was studied in BALB/c and X-chromosome-linked immunodeficient (xid) mice. BALB.xid-infected mice showed lower numbers of larvae. Third-stage larvae, fourth-stage larvae and adult parasites were found in both strains. BALB/c mice produced IgM, IgG, IgA and IgE against the crude extract and secreted/excreted antigens of the parasite. On the other hand, BALB.xid mice did not produce IgM and produced lower levels of IgG and IgA, and similar quantities of IgE.

Evaluation of an enzyme immunoassay for clinical diagnosis of neurocysticercosis in symptomatic patients

INTRODUCTION: Neurocysticercosis is an infection of the human central nervous system caused by the metacestode larvae of Taenia solium. Neurocysticercosis is the most common parasitic disease in developing countries. Epilepsy is the most common clinical manifestation. Difficulties in confirming the diagnosis motivated the evaluation of the enzyme-linked immunosorbent assay on cerebral spinal fluid (CSF). METHODS: Twenty-two patients with NCC and 44 control patients were studied. CSF was analyzed using a commercial ELISA kit developed for NCC. Sensitivity and specificity were measured and a multivariate logistic regression was performed. RESULTS: Sensitivity and specificity of ELISA were 31.8% and 100%, respectively, with accuracy of 77.3%. Only the size of the lesions proved to be important for performance of the test. CONCLUSIONS: The results showed that ELISA contributes to the diagnosis of neurocysticercosis if the result is negative or if the patient has a lesion of 2 cm or more.

Larvicidal activity of crude extracts from Larrea cuneifolia (Zygophyllaceae) and of its metabolite nordihydroguaiaretic acid against the vector Culex quinquefasciatus (Diptera: Culicidae)

INTRODUCTION: The aim of the present study was to analyze the larvicidal activity of different crude extracts of Larrea cuneifolia and its most abundant lignan, nordihydroguaiaretic acid (NDGA), against Culex quinquefasciatus. METHODS: Chloroform, methanol, and aqueous extracts from L. cuneifolia and NDGA were tested against larvae of Cx. quinquefasciatus under laboratory conditions. RESULTS: The chloroform extract showed the highest larvicidal effect, with an estimated LC50 of 0.062 mg/ml. NDGA also demonstrated significant larvicidal activity with an estimated LC50 of 0.092 mg/ml. CONCLUSIONS: These results indicate that the chloroform extract of L. cuneifolia and NDGA are promising insecticides of botanical origin that could be useful for controlling Cx. quinquefasciatus.

Larval control of Anopheles (Nyssorhinchus) darlingiusing granular formulation of Bacillus sphaericus in abandoned gold-miners excavation pools in the Brazilian Amazon Rainforest

INTRODUCTION: Use of a Bacillus sphaericus based mosquito larvicide was evaluated as an intervention for malaria vector control at a mining site in Amapá, Brazil. Impacts on larval and adult densities of the primary vector Anopheles darlingi were measured over the course of a 52 week study period.METHODS: In Calçoene, State of Amapá, gold mining activity occurs in 19 mining sites in gold-miners of Lourenço. Large pools are formed in mining sites and naturally colonized by Anopheles darlingi. During one year, the impact of applications of VectoLex(r) CG to these larval sources was evaluated. Applications of 20kg/ha were made as needed, based on 10 immature (3rd, 4th instars and pupae) surveillance of health and established thresholds. RESULTS: One hundred percent initial control was observed 48h after each treatment. The pools received from 2-10 (5.3±1.6) treatments during the year. The average re-treatment interval in productive pools was 9.4±4.3 weeks. During weeks 3-52 of the study, mean density of late stage larvae was 78% and pupae were 93% lower in the treated pools than in untreated pools (p< 0.0001, n=51) while reduction of adult mosquitoes was 53% in comparison to the untreated area during the last five months of the study, which were the rainy season (p<0.001).CONCLUSIONS:VectoLex(r) CG reduced immature Anopheles darlingi infestation levels during the entire study period, and reduced adult mosquito populations during the rainy season.

Evaluation of larvicidal activity and brine shrimp toxicity of rhizome extracts of Zingiber zerumbet (L.) Smith

Introduction In this study, we used dichloromethane (DCM) and methanol (MeOH) extracts of the Zingiber zerumbet rhizome to evaluate brine shrimp lethality and larvicidal activity on Aedes aegypti and Anopheles nuneztovari mosquitoes. Methods Bioassays were performed by exposing third-instar larvae of each mosquito species to the DCM or MeOH extracts. Results Probit analysis with DCM and MeOH extracts demonstrated efficient larvicidal activity against A. aegypti and A. nuneztovari larvae. Conclusions The DCM and MeOH extracts showed higher activity against A. nuneztovari larvae than against A. aegypti larvae, suggesting that the extracts have species-specific activity.

Bioactivity of plant extracts on the larval and pupal stages of Aedes aegypti (Diptera, Culicidea)

Introduction Aedes aegypti is responsible for the transmission of the dengue and yellow fever viruses. This study evaluated the effects of extracts from Cnidosculos phyllacanthus, Ricinus communis, and Coutarea hexandra on the developmental periods of A.aegypti larvae and pupae. Crude extracts of C. phyllacanthus and C. hexandra and oil from R. communis and C. phyllacanthus were used. Methods Bioassays of the larvicidal and pupicidal effects of these products at different concentrations and times of exposure were evaluated. The lethal and sublethal effects were determined using different concentrations in larvicidal tests. Mortality data were evaluated by Probit analysis to determine the LC50 and LC90 values. Results The vegetable oils from C. phyllacanthus and R. communis demonstrated greater efficiency for larval control with an LC50=0.28µl/mL and an LC90=1.48µl/mL and LC50=0.029µl/mL and a LC90=0.26µl/mL, respectively. In pupal tests toxic effects for all insects were verified after exposure to the products at significant LC50 and LC90 values for 24 and 48h. The effects of sublethal concentrations of C. phyllacanthus (oil) were more effective on the insects. Conclusions The vegetables oils from C. phyllacanthus and R. communis demonstrated greater potential from the control of different developmental periods in the life cycle of this insect.

Fate map of zebrafish left-right organizer

The organizer is a ciliated signalling transient organ, responsible for the patterning of embryo tissues during embryonic development. In higher vertebrates, such as mouse and chick, this organizer (the node and the Hensen’s node, respectively) performs dorsalventral and anteriorposterior axis definition, as well as left-right patterning of the internal organs. In lower vertebrates, such as frog and zebrafish, there is a separate specialized organ for left-right purposes called the Gastrocoel Roof Plate (GRP) and Kupffer’s Vesicle (KV), respectively. It is known that mouse and chick organizer cells give rise to structures like floor plate, notochord, hypochord and somites. Frog GRP originates all these but floor plate. In zebrafish, at 13-14 somite stage (ss) the KV finished its left-right patterning but what happens to this organizer’ cells is still poorly studied. This research attempts to understand the fate and behaviour of the KV cells. We followed the fate of KV cells by live imaging and by tight time-courses with fixed larvae. We assessed in detail their proliferative and death profile, as well as cilia length progression from 9-10 ss until 29-30 ss. We conclude that the KV cells mostly follow the evolutionarily conserved fates described for other organizers. These cells mainly incorporate the notochord and hypochord; few cells incorporate the floor plate and the somites. As a novelty, it is also hypothesized that the hypural cell fate may be among the KV cell fates.

Effects of piperonyl butoxide on the toxicity of the organophosphate temephos and the role of esterases in the insecticide resistance of Aedes aegypti

IntroductionThe effects of piperonyl butoxide (PBO) on the toxicity of the organophosphate temephos (TE) and the role of esterases in the resistance of Aedes aegypti to this insecticide were evaluated.MethodsA. aegypti L4 larvae susceptible and resistant to TE were pre-treated with PBO solutions in acetone at concentrations of 0.125, 0.25, 0.5, 1, and 2% for 24h and subsequently exposed to a diagnostic concentration of 0.02mg/L aqueous TE solution. The esterase activity of the larvae extracts pre-treated with varying PBO concentrations and exposed to TE for three time periods was determined.ResultsAt concentrations of 0.25, 0.5, 1, and 2%, PBO showed a significant synergistic effect with TE toxicity. High levels of esterase activity were associated with the survival of A. aegypti L4 larvae exposed to TE only.ConclusionsThe results of the biochemical assays suggest that PBO has a significant inhibitory effect on the total esterase activity in A. aegypti larvae.

Larvicidal activity of the methanol extract and fractions of the green fruits of Solanum lycocarpum(Solanaceae) against the vector Culex quinquefasciatus (Diptera: Culicidae)

IntroductionThe larvicidal activity of Solanum lycocarpumagainst Culex quinquefasciatus is unknown.MethodsWe evaluated the larvicidal activity of extracts of the green fruits of Solanum lycocarpum against third and fourth instar larvae of C. quinquefasciatus.ResultsDichloromethane and ethyl acetate fractions showed the greatest larvicidal effect at 200mg/L (83.3% and 86.7%, respectively). The methanol and dichloromethane, ethyl acetate, and hydromethanolic fractions demonstrated larvicidal effects against C. quinquefasciatus, with LC50 values of 126.24, 75.13, 83.15, and 207.05mg/L, respectively.ConclusionsThus, when considering new drugs with larvicidal activity from natural products, S. lycocarpum fruits may be good candidate sources.