Testing a method of sampling for entomological determination of transmission of Wuchereria bancrofti to inform lymphatic filariasis treatment strategy in urban settings.

BACKGROUND: There is on-going debate about scale-up of lymphatic filariasis treatment to include urban areas. Determining Wuchereria bancrofti transmission is more complex in these settings and entomological methodologies suggested as a solution as yet have no clear guidance. METHODS: The study was conducted in six communities in Minna and Kaduna cities in Nigeria selected based on pre-disposing risk factors for mosquitoes and Transmission Assessment Survey (TAS) results in 2016 indicating need for treatment (> 1% prevalence). In each community, 4 gravid traps (GT), 15 exit traps (ET) and 21 pyrethrum spray catches (PSC) were used for 5 months targeting a sample size of 10,000 mosquitoes inclusive of at least 1500 Anopheles. Community researchers were selected and trained to facilitate community acceptability and carry out collection. We have evaluated the mosquito sampling and trapping methodology in terms of success at reaching targeted sample size, cost effectiveness, and applicability. RESULTS: Community researchers were influential in enabling high acceptability of the methods of collection and were able to conduct collections independently. Overall, 12.1% of trapping events (one trapping event corresponds to one visit to one trap to collect mosquitoes) were affected by householder actions, weather conditions or trap malfunction leading to lower than optimal catches. Exit traps were the most cost-effective way to catch Anopheles (6.4 USD per trapping event and 12.8 USD per Anopheles caught). Sample size of 10,000 mosquitoes overall in each city was met though Anopheles catch was insufficient in one city. However, sample size was met only in one implementation unit out of the four. CONCLUSIONS: Methods need adapting to maximise Anopheles catch: we propose planning 250 gravid trap and 3724 exit trap trapping events in similar settings in West African urban areas where Culex is dominant, not using pyrethrum spray catches, and weighting trapping events later in the rainy season. Planning should increase involvement of community researchers, incorporate null catches and participants' actions to predict catches. Importantly, evaluation units should be analogous with implementation units, the units at which treatment decisions will be made in the urban context.

Is mass drug administration against lymphatic filariasis required in urban settings? The experience in Kano, Nigeria.

BACKGROUND: The Global Programme to Eliminate Lymphatic Filariasis (GPELF), launched in 2000, has the target of eliminating the disease as a public health problem by the year 2020. The strategy adopted is mass drug administration (MDA) to all eligible individuals in endemic communities and the implementation of measures to reduce the morbidity of those suffering from chronic disease. Success has been recorded in many rural endemic communities in which elimination efforts have centered. However, implementation has been challenging in several urban African cities. The large cities of West Africa, exemplified in Nigeria in Kano are challenging for LF elimination program because reaching 65% therapeutic coverage during MDA is difficult. There is therefore a need to define a strategy which could complement MDA. Thus, in Kano State, Nigeria, while LF MDA had reached 33 of the 44 Local Government Areas (LGAs) there remained eleven 'urban' LGAs which had not been covered by MDA. Given the challenges of achieving at least 65% coverage during MDA implementation over several years in order to achieve elimination, it may be challenging to eliminate LF in such settings. In order to plan the LF control activities, this study was undertaken to confirm the LF infection prevalence in the human and mosquito populations in three urban LGAs. METHODS: The prevalence of circulating filarial antigen (CFA) of Wuchereria bancrofti was assessed by an immuno-chromatography test (ICT) in 981 people in three urban LGAs of Kano state, Nigeria. Mosquitoes were collected over a period of 4 months from May to August 2015 using exit traps, gravid traps and pyrethrum knock-down spray sheet collections (PSC) in different households. A proportion of mosquitoes were analyzed for W. bancrofti, using dissection, loop-mediated isothermal amplification (LAMP) assay and conventional polymerase chain reaction (PCR). RESULTS: The results showed that none of the 981 subjects (constituted of <21% of children 5-10 years old) tested had detectable levels of CFA in their blood. Entomological results showed that An. gambiae s.l. had W. bancrofti DNA detectable in pools in Kano; W. bancrofti DNA was detected in between 0.96% and 6.78% and to a lesser extent in Culex mosquitoes where DNA was detected at rates of between 0.19% and 0.64%. DNA analysis showed that An. coluzzii constituted 9.9% of the collected mosquitoes and the remaining 90.1% of the mosquitoes were Culex mosquitoes. CONCLUSION: Despite detection of W. bancrofti DNA within mosquito specimens collected in three Kano urban LGAs, we were not able to find a subject with detectable level of CFA. Together with other evidence suggesting that LF transmission in urban areas in West Africa may not be of significant importance, the Federal Ministry of Health advised that two rounds of MDA be undertaken in the urban areas of Kano. It is recommended that the prevalence of W. bancrofti infection in the human and mosquito populations be re-assessed after a couple of years.

Ocular morbidity and health seeking behaviour in Kwara state, Nigeria: implications for delivery of eye care services.

BACKGROUND: There is currently limited information as to which conditions are most prevalent in communities in developing countries. This makes effective planning of eye services difficult. METHODS: 3,899 eligible individuals were recruited and examined in a cross-sectional survey in Asa Local Government Area, Nigeria. Those who self-reported an ocular morbidity were also asked about their health-seeking behaviour. Health records of local facilities were reviewed to collect information on those presenting with ocular morbidities. RESULTS: 25.2% (95% CI: 22.0-28.6) had an ocular morbidity in at least one eye. Leading causes were presbyopia and conditions affecting the lens and conjunctiva. The odds of having an ocular morbidity increased with age and lower educational attainment. 10.1% (7.7-13.0) self-reported ocular morbidity; 48.6% (40.4-56.8) of them reported seeking treatment. At the facility level, 344 patients presented with an ocular morbidity over one month, the most common conditions were red (26.3%) or itchy (20.8%) eyes. CONCLUSION: Ocular morbidities, including many non vision impairing conditions, were prevalent with a quarter of the population affected. The delivery of eye care services needs to be tailored in order to address this need and ensure delivery in a cost-effective and sustainable manner.

Review of the publications of the Nigeria national blindness survey: methodology, prevalence, causes of blindness and visual impairment and outcome of cataract surgery.

This is a review of the major publications from the Nigeria national blindness survey in order to highlight major findings and challenges of eye care in Nigeria. The review summarizes methodology and key findings. Survey publications on methodology, prevalence and causes of visual impairment and outcome of cataract surgery were retrieved, reviewed and relevant data extracted, reported and discussed. The study was the largest and more detailed eye survey in Nigeria (15,375 people 40 years and older recruited). Participants had detailed eye examination including visual acuity, autorefractokeratometry, A- scan biometry, visual field and basic eye examination. Cause(s) of visual impairment in each eye using WHO algorithm was determined among participants with vision < 6/12. Some of the participants also had qualitative questions on barriers to uptake of services, quality of life and visual function. Major highlights of the results as contained in the publications include a high prevalence of blindness with 4.2% (95% CI: 3.8-4.6%;),of the study population having blindness (using presenting vision (PVA)) even with best correction the prevalence was 3.4% (95% CI: 3.0-3.8%. The prevalence of SVI using PVA was 1.5% (95% CI: 1.3-1.7%).and with best correction 0.8% (95% CI: 0.7-1.0%). Blindness varied by age groups, sex, literacy level and geopolitical zone. Furthermore, 84% of blindness was due to avoidable causes with cataract responsible for 43% of blindness, glaucoma 16.7%, uncorrected aphakia 8.4% and corneal opacity 7.9%. Of the total 538 eyes that had cataract surgery procedures, 42.7% had couching and the remaining had cataract surgery, but only 41.4% of cataract operated eyes had IOL surgery. Outcome of cataract surgery was good at presentation for only 30.8% of eyes (84 eyes) which improved to 56.8% with correction. The possible remedy for the high burden of needless blindness and harmful eye health practices in Nigeria are discussed.