Nippostrongylus brasiliensis infection leads to impaired reference memory and myeloid cell interference.

Hookworm infection is endemic in developing countries, leading to poor cognitive function-among other disruptions. In this study, the effects of Nippostrongylus brasiliensis infection (a murine model of Necator Americanus) on cognitive function were investigated. Though impaired cognition has been extensively reported, the exact domain of cognition affected is still unknown, hence requiring investigation. The objective of this study was to identify possible cognitive changes during Nippostrongylus brasiliensis infection in mice, using the Morris water maze. Here, we show for the first time that mice infected with Nippostrongylus brasiliensis were able to learn the Morris water maze task, but demonstrated impaired reference memory. Anxiety measured by thigmotaxis in the maze, did not play a role for the observed cognitive impairment. Of further interest, an increase in the number of hippocampal macrophages and microglia with training and/or infection suggested a significant role of these cell types during spatial learning. Together, these experimental mouse studies suggest that helminth infections do have an impact on cognition. Further experimental animal studies on cognition and infection might open new approaches for a better understanding and impact of pathogen infections.

Food preservative potential of essential oils and fractions from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris against mycotoxigenic fungi.

The food preservative potential of essential oils from three aromatic plants Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris and their fractions was investigated against two mycotoxigenic strains each of Aspergillus ochraceus, Penicillium expansum and P. verrucosum. The fungicidal activity was determined and expressed as a Number of Decimal Reduction of the colony forming units per ml (NDR cfu). The influence of pH variation on this activity was studied. The NDR cfu varied with the essential oils and its concentration, the pH of the medium and the strain tested. The essential oils from O. gratissimum exhibited the highest activity against the six fungal strains under the three pH tested. T. vulgaris and C. citratus essential oils were less active against the Penicillium species tested and A. ochraceus, respectively. Potassium sorbate did not present any activity at pH 6 and 9. At pH 3, its NDR cfu was the lowest against the six fungal strains. At the same pH and at 4000 ppm, the three essential oils presented a NRD cfu > or = 6 against strains of A. ochraceus and P. expansum. The same result was obtained with T. vulgaris and C. citratus at 8000 ppm against both strains of P. verrucosum. The highest activity of the three essential oils was recorded at pH 3 against A. ochraceus strains and at pH 9 against both species of Penicillium. From the fractionation, three active fractions were obtained each from C. citratus and O. gratissimum, and two active fractions from T. vulgaris. These active fractions exhibited a NDR cfu, two to seven folds higher than that of the complete essential oils.