No abstract

The role of the Anopheles funestus group in malaria transmission was investigated in two ecological zones in Nigeria. Sampling was carried out at four sites each around Ibadan (forest) and Ilorin (savanna). Human landing catches were supplemented with indoor and outdoor resting collections. PCR was used to identify 1848 A. funestus group mosquitoes to species level (749 in the savanna, 1099 in the forest) and three species were identified. In the forest, A. funestus s.s. predominated (55.4%), followed by A. rivulorum (27.6%) and A. leesoni (17.0%). Anopheles funestus was found mostly indoors. Anopheles rivulorum and A. leesoni predominated in outdoor collections (P<0.001). Only Anopheles funestus s.s. was found in the savanna. ELISA analysis of 803 blood meal-positive specimens showed that over half of the blood meals were taken from humans in both ecotypes. The human blood index in A. funestus from the two study areas was similar. Anopheles funestus s.s. was the only species found positive for Plasmodium falciparum using ELISA, with overall infection rates of 2.3% and 1.0% in the forest and savanna respectively. The presence of three A. funestus species in Nigeria emphasizes the desirability of correct species identification within a malaria vector control programme.

BackgroundPermaNet® 3.0 is an insecticide synergist-combination long-lasting insecticidal net designed to have increased efficacy against malaria vectors with metabolic resistance, even when combined with kdr. The current study reports on the impact of this improved tool on entomological indices in an area with pyrethroid-resistant malaria vectors in Nigeria.MethodsBaseline entomological indices across eight villages in Remo North LGA of Ogun State provided the basis for selection of three villages (Ilara, Irolu and Ijesa) for comparing the efficacy of PermaNet® 3.0 (PN3.0), PermaNet® 2.0 (PN2.0) and untreated polyester nets as a control (UTC). In each case, nets were distributed to cover all sleeping spaces and were evaluated for insecticidal activity on a 3-monthly basis. Collection of mosquitoes was conducted monthly via window traps and indoor resting catches. The arithmetic means of mosquito catches per house, entomological inoculation rates before and during the intervention were compared as well as three other outcome parameters: the mean mosquito blood feeding rate, mean mortality and mean parity rates.ResultsAnopheles gambiae s.l. was the main malaria vector in the three villages, accounting for >98% of the Anopheles population and found in appreciable numbers for 6–7 months. Deltamethrin, permethrin and lambdacyhalothrin resistance were confirmed at Ilara, Irolu and Ijesa. The kdr mutation was the sole resistance mechanism at Ilara, whereas kdr plus P450-based metabolic mechanisms were detected at Irolu and Ijesa. Bioassays repeated on domestically used PN 2.0 and PN 3.0 showed persistent optimal (100%) bio-efficacy for both net types after the 3rd, 6th, 9th and 12th month following net distribution. The use of PN 3.0 significantly reduced mosquito densities with a ‘mass killing’ effect inside houses. Households with PN 3.0 also showed reduced blood feeding as well as lower mosquito parity and sporozoite rates compared to the PN 2.0 and the UTC villages. A significant reduction in the entomological inoculation rate was detected in both the PN 2.0 village (75%) and PN 3.0 village (97%) post LLIN-distribution and not in the UTC village.ConclusionThe study confirms the efficacy of PN 3.0 in reducing malaria transmission compared to pyrethroid-only LLINs in the presence of malaria vectors with P450-based metabolic- resistance mechanisms.

The composition of the essential oils of the leaves and flowers of Tithonia diversifolia (Hemsl) A. Gray, Mexican sunflower, are reported. The oils were obtained by hydrodistillation in an all-glass Clevengertype apparatus and analyzed by GC-MS. The leaf oil was comprised of an abundance of a-pinene (32.9%), b-caryophyllene (20.8%), germacrene D (12.6%), bpinene (10.9%) and 1, 8-cineole (9.1%). Germacrene D (20.3%), b-caryophyllene (20.1%) and bicyclogermacrene (8.0%) characterized the oil of the flower. A number of aliphatic fatty acids and a diterpenoid compound, sandaracopimaradiene, that were present in the flower, could not be detected in the leaf oil.

No abstract