Impacts of ivermectin mass drug administration for onchocerciasis on mosquito populations of Ogun state, Nigeria.

BACKGROUND: The impact of single-dose mass drug administration (MDA) of ivermectin for onchocerciasis on mosquito populations was investigated in Ogun State, Nigeria. METHODS: Indoor and outdoor collection of mosquitoes was carried out in two intervention (IC) and two control communities (CC) at three different periods: pre-MDA (baseline), 2-3 days after MDA and 13-14 days after MDA. The density and parity rate of female Anopheles and Culex mosquitoes were determined and compared. Environmental and climatic data of study locations were obtained to perform generalized linear model analysis. RESULTS: A total of 1399 female mosquitoes were collected, including 1227 Anopheles and 172 Culex mosquitoes. There was a similar magnitude of reduction in the indoor density of Anopheles by 29% in the IC and CC 2-3 days post-MDA but the reduction in indoor parity rate was significantly higher (p = 0.021) in the IC, reducing by more than 50%. In the IC, observation of a significant reduction at 2-3 days post-MDA was consistent for both the indoor density (1.43 to 1.02) and indoor parity rate (95.35% to 44.26%) of Anopheles mosquitoes. The indoor parity rate of Anopheles remained significantly reduced (75.86%) 13-14 post-MDA. On the other hand, the indoor density of Culex increased from 0.07 to 0.10 at 2-3 days post-MDA while the indoor parity rate of Culex did not change. The outdoor density of Anopheles in the IC increased (p = 0.394) from 0.58 to 0.90 at 2-3 days post-MDA; a similar observation was consistent for the outdoor density (2.83 to 3.90) and outdoor parity rate (70.59% to 97.44%) of Culex, while the outdoor parity rate of Anopheles reduced from 85.71 to 66.67% at 2-3 days post-MDA. A generalized linear model showed that ivermectin MDA significantly caused a reduction in both the indoor density (p < 0.001) and indoor parity rate (p = 0.003) of Anopheles in the IC. CONCLUSION: Ivermectin MDA resulted in the reduction of both the survival and density of Anopheles mosquitoes. This has strong implications for malaria transmission, which depends strongly on vector survival.

Biting on human body parts of Simulium vectors and its implication for the manifestation of Onchocerca nodules along Osun River, southwestern Nigeria.

BACKGROUND: The biting preference of Simulium vectors has been known to influence the distribution of Onchocerca nodules and microfilariae in human body. There is, however, variation in biting pattern of Simulium flies in different geographical locations. This study investigates the biting pattern on human parts by Simulium vectors along Osun river system where Simulium soubrense Beffa form has been implicated as the dominant vector and its possible implication on the distribution of Onchocerca nodules on human body along the river. METHODS: Flies were collected by consented fly capturers on exposed human parts namely head/neck region, arms, upper limb and lower limb in Osun Eleja and Osun Budepo along Osun river in the wet season (August-September) and the dry season (November-December) in 2008. The residents of the communities were also screened for palpable Onchocerca nodules. RESULTS: The results showed that number of flies collected below the ankle region was significantly higher than the number collected on other exposed parts (p <0.05) while the least was collected on head/neck region in both seasons. The lower trunk was the most common site (60%) for nodule location at Osun Eleja followed by upper trunk (40%). Nodules were not found in the head and limb regions. At Osun Budepo, the upper trunk was the most common site of the nodule location (53.8%) followed by the lower trunk (38.5%) and head region (7.7%). CONCLUSION: Though, most of the flies were caught at the ankle region, the biting of other parts coupled with the presence of nodules at the head and upper trunk regions showed that Simulium vectors could obtain microfilariae from any part of the body, thus increasing the risk of onchocerciasis transmission.

Rectal artesunates, their utilization, and parental perception in the management of malaria in children from Abeokuta, southwestern Nigeria.

Utilization, efficacy, perception, and acceptability of rectal artesunates for treatment of malaria were assessed in 264 children below 5 years attending two tertiary health facilities in Abeokuta, Nigeria. The children systematically selected were 136 from State Hospital Ijaye and 128 from Federal Medical Centre (FMC), Idi-Aba. Body weights and vital statistics of the children were measured; and blood samples were collected before and 24 h after administration of the rectal artesunates (Plasmotrim-50/200 mg Artesunate) to evaluate the efficacy of the suppository. The first dose of rectal artesunate suppository was administered at a dose of 5-10 mg/kg of body weight per rectum. Giemsa thin and thick films were employed to determine parasite species, malaria parasite count/µL (MPC/µL), and percentage of parasitized red blood cells (PPRBCs). Data were analyzed using SPSS version 16.0. Plasmodium falciparum was the malaria parasite identified by blood examination, with a pretreatment prevalence of 98.9%. Male children had higher infection rate (55%) than females (45%), and infection among age groups and weight groups varied. Chi-square analysis revealed a significant difference between weight and malaria parasite count (p<0.05). Post-treatment analysis after 24 h showed that prevalence dropped by 73%, with females having higher crash rate (77%) than males (69%) but with no statistical difference (p>0.05) among the sexes. Chi-square analysis of pre- and post-treatment revealed a significant difference between MPC/µL and PPRBC at p<0.05. This confirmed the efficacy of rectal artesunate in reducing the parasite density (parasitaemia) within 24 h of treatment. On acceptability, 99.60% of parents accepted to use the suppository. However, 87.1% of parents preferred its usage, as it is easy to administer with no adverse effects when administered on their children. If health officials increase more public knowledge on the use of rectal artesunates, the high mortality now experienced in children under 5 years due to malaria disease would be greatly reduced.

Helminthiasis and hygiene conditions of schools in Ikenne, Ogun State, Nigeria.

BACKGROUND: A study of the helminth infection status of primary-school children and the hygiene condition of schools in Ikenne Local Government Area of Ogun State, Nigeria was undertaken between November 2004 and February 2005 to help guide the development of a school-based health programme. METHODS AND FINDINGS: THREE PRIMARY SCHOOLS WERE RANDOMLY SELECTED: two government-owned schools (one urban and the other rural) and one urban private school. No rural private schools existed to survey. A total of 257 schoolchildren aged 4-15 y, of whom 146 (56.8%) were boys and 111 (43.2%) were girls, took part in the survey. A child survey form, which included columns for name, age, sex, and class level, was used in concert with examination of stool samples for eggs of intestinal helminths. A school survey form was used to assess the conditions of water supply, condition of latrines, presence of soap for handwashing, and presence of garbage around the school compound. The demographic data showed that the number of schoolchildren gradually decreased as their ages increased in all three schools. The sex ratio was proportional in the urban school until primary level 3, after which the number of female pupils gradually decreased, whereas in the private school, sexes were proportionally distributed even in higher classes. The prevalence of helminth infection was 54.9% of schoolchildren in the urban government school, 63.5% in the rural government school, and 28.4% in the urban private school. Ascaris lumbricoides was the most prevalent species, followed by Trichuris trichiura, Taenia species, and hookworm in the three schools. Prevalence of infection in the government-owned schools was significantly higher than in the private school (chi(2) = 18.85, df = 2, p<0.0005). A survey of hygiene conditions in the three schools indicated that in the two government schools tapwater was unavailable, sanitation of latrines was poor, handwashing soap was unavailable, and garbage was present around school compounds. In the private school, in contrast, all hygiene indices were satisfactory. CONCLUSIONS: These results indicate that burden of parasite infections and poor sanitary conditions are of greater public health importance in government-owned schools than in privately owned schools. School health programmes in government-owned schools, including deworming, health education, and improvement of hygiene conditions are recommended.