Status of Onchocerca volvulus infection and transmission by blackflies after 15 years of ivermectin distribution at Adani, Nigeria.

The nuisance bites of blackflies and transmission of Onchocerca volvulus, which causes onchocerciasis, constitutes a threat to public health and an impediment to food production in rural and riverine communities in Nigeria. The entomological profile of onchocerciasis at Adani, Nigeria, was investigated from August 2010 to January 2011 to determine the transmission of O. volvulus after 15 years of ivermectin distribution in the area. A total of 548 adult female blackflies of the Simulium damnosum complex were caught using human baits and dissected. Of this number, 248 flies were caught in the wet season (August to October), while 300 flies were caught in the dry season (November to January). The relative abundance of flies at Adani varied from 21 in December to 243 in January. The monthly catches between September and October and between December and January were significantly different. The monthly population density of the flies ranged from 0.5Flies/Man/Hour (FMH) in December to 5.5FMH in January. The diurnal biting pattern of the S. damnosum complex at the site showed a bimodal peak of activity with the evening peak being higher than the morning peak except in October when the morning peak was higher than the evening peak. The morning peaks were observed between 7.00 am and 10.00 am, whereas the evening peaks occurred between 4.00 pm and 6.00 pm. The morning and evening biting peaks in all the months were not significantly different. Nulliparous flies accounted for 75.7% of the total catch, whereas 24.3% of the flies caught were parous. The infection, infective bites and transmission of O. volvulus during the study period were zero. This study suggests that transmission of O. volvulus has been halted and the flies are presently more nuisance biters than disease vectors since no stage of O. volvulus was found in the flies dissected.

Status of Onchocerca volvulus infection and transmission by blackflies after 15 years of ivermectin distribution at Adani, Nigeria

@#The nuisance bites of blackflies and transmission of Onchocerca volvulus, which causes onchocerciasis, constitutes a threat to public health and an impediment to food production in rural and riverine communities in Nigeria. The entomological profile of onchocerciasis at Adani, Nigeria, was investigated from August 2010 to January 2011 to determine the transmission of O. volvulus after 15 years of ivermectin distribution in the area. A total of 548 adult female blackflies of the Simulium damnosum complex were caught using human baits and dissected. Of this number, 248 flies were caught in the wet season (August to October), while 300 flies were caught in the dry season (November to January). The relative abundance of flies at Adani varied from 21 in December to 243 in January. The monthly catches between September and October and between December and January were significantly different. The monthly population density of the flies ranged from 0.5Flies/Man/Hour (FMH) in December to 5.5FMH in January. The diurnal biting pattern of the S. damnosum complex at the site showed a bimodal peak of activity with the evening peak being higher than the morning peak except in October when the morning peak was higher than the evening peak. The morning peaks were observed between 7.00 am and 10.00 am, whereas the evening peaks occurred between 4.00 pm and 6.00 pm. The morning and evening biting peaks in all the months were not significantly different. Nulliparous flies accounted for 75.7% of the total catch, whereas 24.3% of the flies caught were parous. The infection, infective bites and transmission of O. volvulus during the study period were zero. This study suggests that transmission of O. volvulus has been halted and the flies are presently more nuisance biters than disease vectors since no stage of O. volvulus was found in the flies dissected.

Maternal vitamin A supplementation delays time to first episode of parasitaemia and reduces malaria parasite densities among infants in rural communities in Ebonyi State, Nigeria.

The study was a randomized mother -infant dyad placebo controlled field trial that evaluated the effect of maternal vitamin A supplementation on time to first episode of parasitaemia and on malaria parasite densities among infants in three rural communities in Ebonyi State, Nigeria. One hundred and fifty-two (152) pregnant women with pregnancies that had mature to at least six (6) months were equally randomized into supplemented and placebo groups. Ten thousand international unit (10,000 IU) of vitamin A supplement was administered three (3) times per week to women of the supplemented group while placebo was given to the control group at equal frequencies. The regimen was continued until the participants delivered their babies. On delivery of their babies, 200,000 1U of vitamin A supplement was administered to the supplemented group while the other group also received placebo. The regimen was maintained every three (3) month until the infants were 12 months old. Follow-up was carried out monthly and 3 ml of venous blood was collected quarterly from the infants and used for determination of parasitaemia. The procedure was carried out following standard parasitological techniques. Data collected were analysed using analysis of variance (ANOVA), Fisher's least significant difference (FLSD), and Ttest. Statistical significance was established at p<0.05. Infants of mothers from the placebo group were infected by malaria parasites at earlier months of their lives while their counterparts had parasitaemia much later. Malaria parasite densities significantly differed (p<0.05) among infants of the two groups, with infants of vitamin A supplemented women having lower parasite densities in comparison with their counterparts. Pre-partum and post- partum supplementation of vitamin A within the recommended dosages are required for improvement of nutritional status and well-being of both mothers and infants.

Maternal vitamin A supplementation delays time to first episode of parasitaemia and reduces malaria parasite densities among infants in rural communities in Ebonyi State, Nigeria

@#The study was a randomized mother –infant dyad placebo controlled field trial that evaluated the effect of maternal vitamin A supplementation on time to first episode of parasitaemia and on malaria parasite densities among infants in three rural communities in Ebonyi State, Nigeria. One hundred and fifty-two (152) pregnant women with pregnancies that had mature to at least six (6) months were equally randomized into supplemented and placebo groups. Ten thousand international unit (10,000 IU) of vitamin A supplement was administered three (3) times per week to women of the supplemented group while placebo was given to the control group at equal frequencies. The regimen was continued until the participants delivered their babies. On delivery of their babies, 200,000 1U of vitamin A supplement was administered to the supplemented group while the other group also received placebo. The regimen was maintained every three (3) month until the infants were 12 months old. Follow-up was carried out monthly and 3 ml of venous blood was collected quarterly from the infants and used for determination of parasitaemia. The procedure was carried out following standard parasitological techniques. Data collected were analysed using analysis of variance (ANOVA), Fisher’s least significant difference (FLSD), and Ttest. Statistical significance was established at p<0.05. Infants of mothers from the placebo group were infected by malaria parasites at earlier months of their lives while their counterparts had parasitaemia much later. Malaria parasite densities significantly differed (p<0.05) among infants of the two groups, with infants of vitamin A supplemented women having lower parasite densities in comparison with their counterparts. Pre-partum and post- partum supplementation of vitamin A within the recommended dosages are required for improvement of nutritional status and well-being of both mothers and infants.

Wuchereria bancrofti infection in rural tropical guinea savannah communities: Rapid epidemiological assessment using immunochromatographic card test and prevalence of hydrocoele.

Lymphatic filariasis (LF) caused by the nematode Wuchereria bancrofti is a major public health concern in endemic communities worldwide. Among tropical diseases it is second to malaria in terms of disability adjusted life years. The Nigerian LF elimination programme has been slated for 2015. Currently, there is paucity of published data on the problem in rural Ebonyi State. This survey was conducted in six rural communities of southwestern Ebonyi State to assess its prevalence among the population and provide baseline data for incorporation into the national LF elimination programme. Immunochromatographic card test (ICT) for detecting circulating filarial antigen (CFA) using whole blood and overt clinical manifestations (lymphoedema and hydrocoele) were used as epidemiological tools. All the studied communities were endemic for active bancroftian filariasis. Of the 600 randomly selected subjects aged ≥10 years, an overall prevalence of 23.50% was established (range, 17.00 - 30.00%). Overall, the antigenaemic prevalence was similar; there was a trend of slightly higher prevalence in males (24.34%) than females (22.39%). The between-gender prevalence difference was not statistically significant (χ² = 8.16, df = 1, p = 0.05) based on CFA positivity. Antigenaemia prevalence was age-dependent, increased exponentially and peaked at 20.57% in subjects in the 40-49 years age category. Lymphoedema and hydrocoele attributable to W. bancrofti were observed in 4.05% of subjects examined. Generally, hydrocoele was observed in 1.69% males, whereas lymphoedema was presented by 2.36% (1.35% females; 1.01% males) of studied population. None of the male subjects had both the two clinical features. Results of this study showed that W. bancrofti infection is widespread in southwestern Ebonyi State, Nigeria, and is a major health issue. There is a need for mass mobilization, mass education and community involvement in sustained intervention programme toward lymphatic filariasis elimination.

Prevalence and transmission dynamics of Schistosoma haematobium infection in a rural community of southwestern Ebonyi State, Nigeria.

A twelve-month epidemio-ecological study on the prevalence, infection intensity, water contact and vector aspects of urinary schistosomiasis was conducted in a rural community of south-west Ebonyi State, Nigeria, using standard procedures, and involving 894 individuals (527, 58.9% males; and 367, 41.1% females). An overall community prevalence (15.3%) was established with more males (20.7%) than females (7.6%) being significantly positive for both micro-and macro-haematuria (χ² = 0.806; df = 1, p < 0.05). Intensity of infection was generally of the light category (< 100 eggs/10 ml urine) with more infected males (n = 95, 87.2%) than infected females (n = 15, 53.6%). Correlation analysis showed no linear relationship between prevalence and intensity of infection. Individuals aged 16-20 years dominated interschool/intervillage infection profile (range 13.2-50%) while participants in 6-10 years age bracket recorded the lowest infection rates (range 2.8-5.0%). Age-related difference in prevalence was not significant (χ² = 1.80; df = 2, p > 0.05). A total of 2877 ova of Schistosoma haematobium were recovered providing an overall mean egg burden of 21 ± 7 eggs/10 ml urine per infected person. Age-related infection intensity was similarly of the light category involving 80.3% of infected persons. Bulinus globosus (n = 308) was identified as the vector of the parasite with 20.1% snails found to be shedding cercariae. Monthly and seasonal infection rates in snails were season-dependent and peaking in May (35.5%). Participants aged 13-15 years accounted for 25.1% of total water contacts (n = 9938) whereas individuals aged 6-9 years accounted for only 9.6% contacts. The most performed water contact activity was bathing (33.3%), followed by washing of clothes (25.7%). Correlation analysis indicated that village of residence, age and cumulative water contacts were significant correlates of possible S. haematobium infection.

Urinary schistosomiasis among pregnant women in some endemic tropical semi - urban communities of Anambra State, Nigeria.

Urinary schistosomiasis is caused by the deposition of eggs by adult flukes in the blood vessels surrounding the bladder of the infected host. Schistosomiasis is ranked the second most important parasitic disease of man and undoubtedly the most important of helminth origin. This paper reports the prevalence of Schistosoma haematobium infection among pregnant women in some endemic tropical semi - urban communities of Anambra State, Nigeria, screened using Medi-Test Combi 9 and urine centrifugation methods. Laboratory analysis of urine samples collected from 172 pregnant women indicated that 41 (23.8%) had urinary schistosomiasis with Anam community having the highest prevalence of 35.1% among other communities. The overall prevalence and intensity of infection among age groups showed that the youngest age group in the study, 16-20 years had the highest prevalence. Out of 24 women within this age group, 12 (50.0%) were infected among which 8 (33.3%) had light infection while 4 (16.6%) had moderate infection. The peak mean intensity of 7.6 eggs/10ml urine was observed in age group 16-20 years while the oldest age group, 41-45 years had the lowest mean intensity of 1.0 egg/10ml urine. Haematuria and proteinuria which are diagnostic for schistosomiasis were higher within age group 16-20 years in all the communities with Anam community having the highest prevalence of 50% for both biochemicals within age group 16-20 years. The findings from this study will be useful in developing specific programme for this special group of women.

Urinary schistosomiasis among pregnant women in some endemic tropical semi – urban communities of Anambra State, Nigeria

Urinary schistosomiasis is caused by the deposition of eggs by adult flukes in the blood vessels surrounding the bladder of the infected host. Schistosomiasis is ranked the second most important parasitic disease of man and undoubtedly the most important of helminth origin. This paper reports the prevalence of Schistosoma haematobium infection among pregnant women in some endemic tropical semi – urban communities of Anambra State, Nigeria, screened using Medi-Test Combi 9 and urine centrifugation methods. Laboratory analysis of urine samples collected from 172 pregnant women indicated that 41 (23.8%) had urinary schistosomiasis with Anam community having the highest prevalence of 35.1% among other communities. The overall prevalence and intensity of infection among age groups showed that the youngest age group in the study, 16-20 years had the highest prevalence. Out of 24 women within this age group, 12 (50.0%) were infected among which 8 (33.3%) had light infection while 4 (16.6%) had moderate infection. The peak mean intensity of 7.6 eggs/10ml urine was observed in age group 16-20 years while the oldest age group, 41-45 years had the lowest mean intensity of 1.0 egg/10ml urine. Haematuria and proteinuria which are diagnostic for schistosomiasis were higher within age group 16-20 years in all the communities with Anam community having the highest prevalence of 50% for both biochemicals within age group 16-20 years. The findings from this study will be useful in developing specific programme for this special group of women.

Malaria control and treatment strategies among school children in semi-urban tropical communities.

BACKGROUND: Plasmodium infections among school children in Igbo-Eze South Local Government of Enugu State, Nigeria, were studied between July and December 2005. The relationship between the use of malaria control measures and the prevalence of Plasmodium infections was investigated. METHODS: Blood smears were obtained from 1296 school children (ages 4-15 years) from six schools randomly sampled from the study area. Drugs were given to infected children. Epidemiological questionnaires were administered to the children. RESULTS: Out of 1296 school children examined, 270 (20.8%) had Plasmodium falciparum infections. The prevalence of these parasitic infections varied significantly (p < 0.05) among schools, with Central School, Ovoko (30.1% P falciparum) and Community primary school, Itchi (13.9%), having the highest and lowest prevalence rates respectively. Furthermore, the prevalence of P falciparum infections also varied significantly (p < 0.05) among the age groups, with age groups 4-6 (35.1%) and 10-12 (14.2%) having the highest and lowest prevalence rates respectively. Males (23.1%) had a significantly higher prevalence rate than females (18.5%). The prevalence of malaria was significantly lower among pupils using preventive measures; 5.9% among pupils using mosquito bed net as against 21.2% among those not using bed nets and 4.6% for pupils living in screened houses as against 24.1% for those not living in screened houses. CONCLUSION: The study revealed that malaria is a major public health problem among pupils in a Nigerian local community. Prevalence rates among pupils varied among location of schools, age and gender. Preventive measures favoured the use of bed nets and living in screened houses.