Public Health Parasitology and Entomomology

The use of community residents as agents for distributing mass ivermectin therapy for onchocerciasis provides a component of community participation absent from mobile team delivery methods. Community-based distribution, however, presupposes preexisting human resources in the endemic villages capable of fulfilling the essential functions of an ivermectin distribution process: mobilizing and educating the population, dispensing the drug, maintaining records, and monitoring and treating adverse reactions. Even when such human resources exist, the community workers must continue to receive tangible support from both external (government and donor agencies) and internal (community) sources. Donor and government agencies must accept that their data collection demands will be limited by the literacy standards of the communities being served. Community leaders must agree to set and use their own local standards of payment (including food stuffs or exchange in kind) to compensate the distributors for their time and efforts. The use of locally available human and remunerative resources is a prerequisite for true community ownership of a program.

We determined whether the school-based "disease mapping" methodology used to assess urinary schistosomiasis (SCH) is useful for determining trachoma interventions and whether the district-based approach recommended for trachoma is useful for SCH control programs. We conducted two separate integrated surveys in eight districts of central Nigeria: school based and district based. A total of 17,189 children were examined for trachoma and 16,238 children were examined for hematuria from 363 schools and 2,149 households. School surveys identified 67 communities warranting praziquantel drug treatment of SCH and 142 trachoma-endemic communities warranting trachoma control activities. In district-level estimates, we identified 24 communities for praziquantel treatment and 0 for trachoma intervention. Integrating trachoma into SCH school-based surveys, and SCH into trachoma surveys, was quick and easy, but in this setting, school-based surveys were more useful for identifying communities where intervention is warranted.

The results of previous studies in Nigeria indicate that 81% of the villages in Plateau and Nasarawa states probably qualify for the mass administration of praziquantel (PZQ) because of Schistosoma haematobium (SH) and/or S. mansoni (SM) infection. To determine the best strategy, relative costs were modelled for four different programmatic approaches to mass drug administration (MDA) at village level. The approaches considered were (1) village-by-village screening for SH (using dipsticks to test for haematuria), with MDA confined to those villages where at least 20% of school-aged children were found infected; (2) screening for both SM (using Kato-Katz smears) and SH, with MDA confined to those villages where at least 20% of school-aged children were found infected with SH or at least 10% of such children were found SM-positive; (3) the presumptive annual treatment of all school-aged children with PZQ (without village-by-village screening); and (4) the presumptive annual treatment of all eligible adults and children with PZQ. In the MDA in models 1 and 2, treatment is only given to children unless the prevalence of schistosome infection is >or=50%, when adults are also treated. As first-year 'assessment' costs were particularly high for the models that included screening, costs were projected over 5 years for all four models. The total 5-year costs, to cover a population of 30,000, were U.S.$18,673 for the model with screening only for SH, U.S.$36,816 for the model with screening for both SH and SM, U.S. $15,510 for the treatment of all school-aged children, and U.S.$68,610 for the treatment of the entire population. Although the presumptive treatment of school-aged children appeared to be the cheapest approach, it would exclude the community-wide treatment of highly endemic communities, the importance of which needs further study.

In areas of Nigeria where onchocerciasis is endemic, community-directed distributors (CDD) distribute ivermectin annually, as part of the effort to control the disease. Unfortunately, it has been reported that at least 35% of the distributors who have been trained in Nigeria are unwilling to participate further as CDD. The selection and training of new CDD, to replace those unwilling to continue, leads to annual expense that the national onchocerciasis-programme is finding difficult to meet, given other programme priorities and the limited resources. If the reported levels of attrition are true, they seriously threaten the sustainability of community-directed treatment with ivermectin (CDTI) in Nigeria. In 2002, interviews were held with 101 people who had been trained as CDD, including those who had stopped serving their communities, from 12 communities in south-eastern Nigeria that had high rates of CDD attrition. The results showed that, although the overall reported CDD attrition was 40.6%, the actual rate was only 10.9%. The CDD who had ceased participating in the annual rounds of ivermectin blamed a lack of incentives (65.9%), the demands of other employment (14.6%), the long distances involved in the house-to-house distribution (12.2%) or marital duties (7.3%). Analysis of the data obtained from all the interviewed CDD showed that inadequate supplies of ivermectin (P<0.01), lack of supervision (P<0.05) and a lack of monetary incentives (P<0.001) led to significant increases in attrition. Conversely, CDD retention was significantly enhanced when the distributors were selected by their community members (P<0.001), supervised (P<0.001), supplied with adequate ivermectin tablets (P<0.05), involved in educating their community members (P<0.05), and/or involved in other health programmes (P<0.001). Although CDD who were involved in other health programmes were relatively unlikely to cease participating in the distributions, they were more likely to take longer than 14 days to complete ivermectin distribution than other CDD, who only distributed ivermectin. Data obtained in interviews with present and past CDD appear vital for informing, directing, protecting and enhancing the performance of CDTI programmes, in Nigeria and elsewhere.

Both Schistosoma haematobium and S. mansoni are endemic in Nigeria. Since 1999 the ministries of health of Plateau and Nasarawa states, assisted by The Carter Center, have provided mass drug administrations with praziquantel to villages where >20% of the school-aged children tested with urine dipsticks have been found to have haematuria (presumed to be caused by S. haematobium). The current extent of S. mansoni in Nigeria remains relatively unknown because the tests needed to detect human infection with this parasite are difficult to perform in many endemic areas. In a cross-sectional survey involving 924 children, the prevalence of S. mansoni was determined in 30 villages (in four local government areas) that had been excluded from mass praziquantel administrations because the prevalence of haematuria in their school-aged children had been found to be <20%. Seventeen (57%) of the surveyed villages had sufficient S. mansoni (i.e. prevalences of at least 10%) to warrant treatment. The results indicated that, if both S. haematobium and S. mansoni are taken into account, 81% of the villages in the four local government areas studied require treatment, compared with 50% if only S. haematobium is considered. At the moment, the costs of the village-by-village diagnosis of S. haematobium and S. mansoni would be greater than those of the presumptive treatment of the school-aged children in all villages. Until improved and cheaper rapid diagnostic methods for S. mansoni become available, the cheapest approach to the overall problem of schistosomiasis in this part of Nigeria would therefore be wide-spread mass drug distributions, without screening for at-risk populations.

The World Health Organization has called upon member states to eliminate blinding trachoma by 2020 using the SAFE strategy. We aimed to determine the prevalence of trachoma and quantify intervention needs for each aspect of the SAFE (surgery, mass administration of antibiotics, promotion of facial cleanliness and environmental improvements) strategy in Nasarawa and Plateau States, Nigeria. District-based, household cluster surveys were conducted in all 30 local government areas (LGAs) within the states. A total of 46 960 persons were examined from 7883 selected households. Prevalence estimates of trachomatous inflammation follicular among children 1-9 years of age ranged from 1.7 to 15.8% by LGA. Trichiasis prevalence among adults varied by LGA from 0 to 2.1% and was more common among women (OR = 1.99, 95% CI 1.3 to 3.1). Access to water within a 30 min round trip was reported by 82.3% of households. LGA-wide trachoma control interventions are warranted in seven LGAs targeting: 5409 persons for surgery to correct trichiasis, 778 698 persons to receive at least three rounds of mass antibiotic distribution, 855 villages in which to promote face-washing and sanitation, and 102 751 households for latrine construction. These mapping surveys demonstrate an example of evidence-based programme planning necessary for measuring progress towards achieving the GET 2020 objective and can be replicated in other areas yet to be mapped for trachoma.

To assess the prevalence of trachomatous inflammation follicular (TF) in children aged 1-9 years and trachomatous trichiasis (TT) in adults aged 15 years or more in Katsina State, Nigeria. Cross sectional population-based trachoma prevalence surveys were conducted using multistage cluster random sampling methodology and the WHO simplified grading system for trachoma in ten local government areas (LGAs). Individual and household risk factors were recorded using a standard questionnaire. A total of 11,407 children and 8,901 adults from 2,244 households were surveyed. Prevalence of TF in children aged 1-9 years ranged from 5.0 to 24.0%. Five LGAs exceeded the 10% threshold for intervention and a further three exceeded 10% in the 95% confidence limits. The prevalence of TT in adults aged 15 years or more ranged from 2.3 to 8.0%: all ten LGAs exceeded the 1% intervention threshold. Analysis of risk factors for active trachoma (TF and/or TI) in children showed the following significant independent associations: Presence of ocular discharge OR = 2.34 (95%CI 1.81-3.03); presence of nasal discharge OR = 1.44 (1.22-1.70); reported frequency of face washing once versus at least twice per day OR = 1.27 (1.02-1.58); disposal of trash inside the compound OR = 1.23 (1.02-1.48); and the absence of a household latrine OR = 1.43 (1.15-1.78). A trachoma control program is warranted in Katsina. Surgical interventions to correct TT are needed immediately in all LGAs surveyed and the full SAFE strategy is justified for five of the ten LGAs, and possibly for another three.

This study was undertaken in five onchocerciasis/lymphatic filariasis (LF) co-endemic local government areas (LGAs) in Plateau and Nasarawa, Nigeria. Annual MDA with ivermectin had been given for 17 years, 8 of which were in combination with albendazole. In 2008, assessments indicated that LF transmission was interrupted, but that the MDA had to continue due to the uncertain status of onchocerciasis transmission. Accordingly, assessments to determine if ivermectin MDA for onchocerciasis could be stopped were conducted in 2009. We evaluated nodule, microfilarial (mf) skin snip, and antibody (IgG4 response to OV16) prevalence in adults and children in six sentinel sites where baseline data from the 1990s were available. We applied the 2001 WHO criteria for elimination of onchocerciasis that defined transmission interruption as an infection rate of <0.1% in children (using both skin snip and OV16 antibody) and a rate of infective (L3) blackflies of <0.05%. Among adult residents in sentinel sites, mean mf prevalence decreased by 99.37% from the 1991-1993 baseline of 42.95% (64/149) to 0.27% (2/739) in 2009 (p<0.001). The OV16 seropositivity of 3.52% (26/739) among this same group was over ten times the mf rate. No mf or nodules were detected in 4,451 children in sentinel sites and 'spot check' villages, allowing the exclusion of 0.1% infection rate with 95% confidence. Seven OV16 seropositives were detected, yielding a seroprevalence of 0.16% (0.32% upper 95%CI). No infections were detected in PCR testing of 1,568 Simulium damnosum s.l. flies obtained from capture sites around the six sentinel sites. Interruption of transmission of onchocerciasis in these five LGAs is highly likely, although the number of flies caught was insufficient to exclude 0.05% with 95% confidence (upper CI 0.23%). We suggest that ivermectin MDA could be stopped in these LGAs if similar results are seen in neighboring districts.

During annual rounds of mass treatment against onchocerciasis, women who are pregnant or nursing neonates should not to be offered ivermectin. The aim of the present study was to determine how many women were not treated, as a result of this policy, in four villages in south-eastern Nigeria. Of the 1714 women of reproductive age present during the 2000 round of mass treatment, 599 (35%) were excluded because they were pregnant or nursing babies aged < 1 month. Most (56%) of the 599 excluded women were, however, treated individually later in the year. Of the 264 excluded women who did not receive a dose of ivermectin at all in 2000, 123 (47%) said they would have actively sought ivermectin treatment had they been made aware of the short duration of exclusion for nursing. If they had all known of the short duration of the exclusion and when and how to locate and receive treatment in their villages after the round of mass treatment, 91% of the women excluded from the round of mass treatment would probably have been treated later in the year. Better treatment systems, follow-up and health education, targeted at pregnant and lactating women, would improve treatment coverage of this group after parturition and early nursing.

In Africa anopheline mosquitoes transmit malaria and lymphatic filariasis (LF); insecticide-treated bed nets significantly reduce transmission of both. Insecticide-treated bed net provision to children under 5 (U5) and pregnant women (PW) is a major goal of malaria control initiatives, but use in Africa remains low because of cost and logistics. We therefore integrated insecticide-treated bed net distribution with the 2004 LF/onchocerciasis mass drug administration (MDA) program in Central Nigeria. Community volunteers distributed 38,600 insecticide-treated bed nets, while simultaneously treating 150,800 persons with ivermectin/albendazole (compared with 135,600 in 2003). This was subsequently assessed with a 30-cluster survey. Among surveyed households containing U5/PW, 80% (95% CI, 72-87%) owned > or = 1 insecticide-treated bed net, a 9-fold increase from 2003. This first linkage of insecticide-treated bed net distribution with mass drug administration resulted in substantial i...