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Malaria is still regarded as a major public health problem in sub-Saharan African countries. Anopheles mosquitoes have been implicated as the major malaria vectors. However, species abundance, composition and distribution vary between different ecological zones. This study investigated the composition and distribution of Anopheles gambiae mosquitoes in Itu Local Government Area, Akwa Ibom State, Nigeria. Adult Anopheles mosquitoes were sampled bi-weekly from 15 randomly selected houses each from three communities in the study area by pyrethroid spray capture (PSC) method. Adult Anopheles species were identified morphologically and sibling species were further subjected to species- specific polymerase chain reaction (PCR) typing. A total of 269 female Anopheles species were caught between July and December, 2015. The study indicated significant (p<0.05) abundance of Anopheles gambiae siblings, with An. gambiae s.s recording 219(81.41%) followed by An. arabiensis 32(11.90%). A proportion of the samples were unidentified 18(6.69%). There was a significant difference (p<0.05) in the distribution of A. gambiae complex over the period of the study with a peak in September 89(33.01%). Anopheles mosquitoes were more abundant in Itu Oma 120(44.66%) than West Itam 98(36.43%) and East Itam 51(18.96%). The study also recorded significantly (p<0.05) higher rate of blood engorged female Anopheles (54.05%). This finding showed that An. gambiae s.s was the predominant malaria vector in the area and also, the incidence of malaria been likely to increase during the wet season. Therefore, vector control must be carried out in these communities to reduce the number of these indoor biting mosquitoes. This study therefore, will be useful as baseline data to help design strategies for malaria control in Itu Local Government Area and also facilitate the success of the ongoing effort on the malaria control programme in the State. [ABSTRACT FROM AUTHOR]

Background & Objectives: Onchocerciasis is endemic in some parts of Akwa Ibom State, Nigeria. This study describes the entomological parameters of transmission in three rural communities of Akwa Ibom State, prior to ivermectin intervention in 2004., Methods: Blackflies were caught using human bait and 90% of the flies were dissected for parity. All parous flies were further dissected for the presence of filaria larvae. Monthly and annual biting rate, and transmission potential were calculated using standard methods., Results: A total of 4296 adult Simulium damnosum were caught on human bait, 4119 were dissected of which 208 (5.1%) were infected with Onchocerca volvulus larvae. Transmission parameters varied significantly (p < 0.05) in the three villages. Annual biting rates, ranged from 9490 to 11,218 bites per person per year. The annual transmission potential ranged from 131 to 189 infective larvae per person per year, monthly biting rate and monthly transmission potential varied significantly (p < 0.05) in the three villages. Transmission was highly seasonal occurring during the peak of rainy season from August to October. There was no transmission during the dry periods--November to March, and the early rainy periods--April to May. The diurnal biting activity of the fly exhibited a bimodal pattern with a morning peak (0900-1000 hrs) and a more marked evening peak (1600-1700 hrs)., Interpretation & Conclusion: The results indicate that there is a temporal and spatial variation in the transmission dynamics of S. damnosum in the study area.

To determine the repellent activity of Ocimum gratissimum volatile oil against Simulium damnosum (blackflies), a 12 month (January-December 2003) field study was conducted in three onchocerciasis endemic communities (Idomido, Obio camp, and Ikot Adaha) in Ini Local Government Area of Akwa Ibom State, Nigeria. The result revealed that topical application of 20% (v/v) concentration of the oil with liquid paraffin as a base, reduced the biting rate of S. damnosum by 90.2, 81.6, and 79.7%, in Idomido, Obiocamp, and Ikot Adaha respectively. The oil gave protection against the bite of S. damnosum for at least 3 h. A total of 710 adults S. damnosum were caught by individuals treated with Ocimum oil, as against 4296 caught by the control group. When the flies caught by the treated individuals were dissected none of them was infected with microfilariae of Onchocerca volvulus. Human-vector contact and onchocerciasis transmission could be reduced by the topical application of the volatile oil during the peak biting periods of the vector