Plasmodium vivax and Plasmodium falciparum infection in Neotropical primates in the western Amazon, Brazil.

The Brazilian Amazon is endemic for malaria and natural infections by Plasmodium spp. have been detected in Neotropical primates. Despite the diversity of primate species in the region, studies on infections by these agents are limited. The aim of the present study was to investigate the frequency of infection by Plasmodium vivax and P. falciparum in free-born primates that were kept in captivity, in the western Amazon, Brazil. Blood samples were collected from 98 Neotropical primates. Detection of P. vivax and P. falciparum DNA was performed using a semi-nested PCR, and the amplified products were sequenced. Plasmodium spp. DNA was detected in 6.12% (6/98) of the primates. P. vivax, and P. falciparum DNA was detected in 2.04% (2/98) and 4.08% (4/98) of these mammals, respectively. Sequencing and phylogenetic analysis confirmed the results obtained from the semi-nested PCR. The presence of infected non-human primates (NHP) can be auxiliary in the maintenance of P. falciparum and P. vivax and may have implications for the malaria surveillance and control in the Brazilian Amazon. It is necessary to structure an efficient surveillance system for the aetiological agents of malaria that infect NHP and humans to reduce the risk of Plasmodium spp. introduction into new areas, to protect all susceptible species.

Clinical Validation of a Commercial LAMP Test for Ruling out Malaria in Returning Travelers: A Prospective Diagnostic Trial.

The mainstay of malaria diagnosis relies on rapid diagnostic tests (RDTs) and microscopy, both of which lack analytical sensitivity. This leads to repeat testing to rule out malaria. A prospective diagnostic trial of the Meridian illumigene Malaria assay (loop-mediated isothermal amplification [LAMP]) was conducted comparing it with reference microscopy and RDTs (BinaxNOW Malaria) in returning travelers between June 2017 and January 2018. Returning travelers with signs and symptoms of malaria were enrolled in the study. RDTs, microscopy, and LAMP assays were performed simultaneously. A total of 298 patients (50.7% male; mean age, 32.5 years) were enrolled, most visiting friends and relatives (43.3%), presenting with fever (88.9%), not taking prophylaxis (82.9%), and treated as outpatients (84.1%). In the prospective arm (n = 348), LAMP had a sensitivity of 98.1% (95% confidence interval [CI], 90.0%-100%) and a specificity of 97.6% (95% CI, 95.2%-99.1%) vs microscopy. After discrepant resolution with real-time polymerase chain reaction, LAMP had a sensitivity of 100% (95% CI, 93.7%-100%) and a specificity of 100% (95% CI, 98.7%-100%) vs microscopy. After discrepant resolution, RDTs had a sensitivity of 83.3% (95% CI, 58.6%-96.4%) and a specificity of 96.2% (95% CI, 93.2%-98.1%) vs microscopy. When including retrospective specimens (n = 377), LAMP had a sensitivity of 98.8% (95% CI, 93.2%-100%) and a specificity of 97.6% (95% CI, 95.2%-99.1%) vs microscopy, and after discrepant resolution of this set, LAMP had a sensitivity of 100% (95% CI, 95.8%-100%) and a specificity of 100% (95% CI, 98.7%-100%). A cost-benefit analysis of reagents and labor suggests savings of up to USD$13 per specimen using a novel algorithm with LAMP screening.

Ligation of the abdominal esophagus decreases scorpion toxin-induced gastric secretion in rats

PURPOSE: Scorpion toxin purified from Tityus serrulatus venom (Tx) induces an increase in volume, acidity and pepsin secretion in the gastric juice of rats. Ligation of oesophagus has been shown to reduce the acid gastric secretion in rats. The aim of this paper was to determine the influence of the esophageal ligation on gastric secretion induced by Tx in rats. METHODS: Forty-four male albino rats were given water ad libitum, but no food for 20 to 24 hours, anesthetized with urethane and the trachea and jugular vein cannulated. Cervical or abdominal esophageal ligation or sham-operations were performed before and after the injection of 0.25 mg/kg of scorpion toxin (fraction Tl) into the jugular vein. One hour later, the volume, acidity, pH and peptic activity of gastric juice were determined. RESULTS: The scorpion toxin induced an increase in gastric juice volume, acidity and pepsin output and a decrease in pH when injected into the vein of intact animals or in sham-operated animals. Cervical esophagus ligation did not interfere with the effects of toxin, however, ligation of the abdominal esophageal decreased the toxin effect on the rat stomach. CONCLUSION: Ligation of the abdominal esophagus decreases the gastric secretion induced by scorpion toxin.

The mouse as an experimental model for tityus serrulatus scorpion envenoming

The scorpion toxin induces a number of physiological parameters alterations, as disturbance of cardiac rhythm, heart failure, shock, pancreatic hypersecretion, abortion, respiratory arrhytmias and pulmonary edema. As the purification of the venom fractions is a laborious process, one alternative for this would be the utilization of small animals. We utilized in the o present study thity-six mice that received progressive doses of scorpion toxin TsTX), i.p. or i.v., and were observed for three hours or sacrificed, and the pulmonary alterations were determined by the lung-body index and by histological analysis of the lungs in order to determine if the mouse can be an esperimental model for scorpion envenomation. The data were analyzed by One Way analysis of variance with p<0,05 indicating significance. These experiments showed no differences in clinical signs of scorpion envenomation between mice and other mammalians, the effects were dose-dependent and the i.v. administration needed less quantity to produce the same changings. In the pulmonary histology we observed septal but not alveolar edema, and we presumed that these differences are due to species-specific variations.