Emmanuel Emukah

Factors affecting the attrition of community-directed distributors of ivermectin, in an onchocerciasis-control programme in the Imo and Abia states of south-eastern Nigeria.

Abstract 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.

Community-Wide Distribution of Long-Lasting Insecticidal Nets Can Halt Transmission of Lymphatic Filariasis in Southeastern Nigeria

Lymphatic filariasis (LF) in rural southeastern Nigeria is transmitted mainly by Anopheles spp. mosquitoes. Potential coinfection with Loa loa in this area has prevented use of ivermectin in the mass drug administration (MDA) strategy for LF elimination because of potential severe adverse L. loa-related reactions. This study determined if long-lasting insecticidal net (LLIN) distribution programs for malaria would interrupt LF transmission in such areas, without need for MDA. Monthly entomologic monitoring was conducted in sentinel villages before and after LLIN distribution to all households and all age groups (full coverage) in two districts, and to pregnant women and children less than five years of age in the other two districts. No change in human LF microfilaremia prevalence was observed, but mosquito studies showed a statistically significant decrease in LF infection and infectivity with full-coverage LLIN distribution. We conclude that LF transmission can be halted in southeastern Nigeria by full-coverage LLIN distribution, without MDA.

Effects of annual mass treatment with ivermectin for onchocerciasis on the prevalence of intestinal helminths.

We evaluated the effect of annual ivermectin (IV) distribution for onchocerciasis on the prevalence of soil transmitted helminth (STH) infections in school-aged (SAC) and preschool-aged (PAC) children by comparing children in villages that had received treatment for 13 years to those from socioeconomically similar villages in untreated areas. We enrolled 1,031 SAC and 211 PAC for Kato Katz examinations. Treated areas had a lower prevalence of Ascaris (SAC: 3% versus 12%, P < 0.0001; PAC: 3% versus 10%, P < 0.051) and Trichuris (SAC: 6% versus 10%, P = 0.012; PAC: 1% versus 8%, P = 0.019), but not hookworm (SAC: 38% versus 42%, P = 0.20; PAC: 21% versus 27%, P = 0.30). The prevalence of Ascaris or Trichuris in treated areas was below the WHO threshold for mass antihelminthic treatment (MDA), but not for hookworm. We conclude that benzimidazole MDA in IV treatment areas is indicated to effectively control hookworm.

Urine heme dipsticks are useful in monitoring the impact of praziquantel treatment on Schistosoma haematobium in sentinel communities of Delta State, Nigeria.

Nigeria is highly endemic for infection with Schistosoma haematobium, which most commonly manifests itself with blood in urine. To monitor the impact of annual mass drug administration (MDA) with Praziquantel for S. haematobium in Delta State, Nigeria, cross-sectional hematuria surveys of school children were conducted in 8 sentinel villages (SVs) at baseline (n=240) and after two annual doses (n=402). We assessed the comparability of three assessments of hematuria (childs reported history, nurse visual diagnosis (NVD) and dipstick) to determine the need for mass treatment. Dipstick was considered to be the gold standard. Prior to treatment, history and NVD each identified only the 3 most highly prevalent SVs, and overall this represented just 37.5% of the 8 SVs in need of treatment. Following treatment, after dipstick prevalence decreased by 88.5% (p<0.001), and history and NVD identified only one of two villages still needing treatment. The study suggests that dipsticks should be the recommended method for launching and monitoring mass treatment for S. haematobium.

Missed treatment opportunities, for pregnant and breast-feeding women, in onchocerciasis mass-treatment programmes in south-eastern Nigeria

Abstract 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.

Determinants of Bed Net Use in Southeast Nigeria following Mass Distribution of LLINs: Implications for Social Behavior Change Interventions.

Millions of long-lasting insecticide treated nets (LLINs) have been distributed as part of the global malaria control strategy. LLIN ownership, however, does not necessarily guarantee use. Thus, even in the ideal setting in which universal coverage with LLINs has been achieved, maximal malaria protection will only be achieved if LLINs are used both correctly and consistently. This study investigated the factors associated with net use, independent of net ownership. Data were collected during a household survey conducted in Ebonyi State in southeastern Nigeria in November 2011 following a statewide mass LLIN distribution campaign and, in select locations, a community-based social behavior change (SBC) intervention. Logistic regression analyses, controlling for household bed net ownership, were conducted to examine the association between individual net use and various demographic, environmental, behavioral and social factors. The odds of net use increased among individuals who were exposed to tailored SBC in the context of a home visit (OR = 17.11; 95% CI 4.45–65.79) or who received greater degrees of social support from friends and family (ptrend < 0.001). Factors associated with decreased odds of net use included: increasing education level (ptrend = 0.020), increasing malaria knowledge level (ptrend = 0.022), and reporting any disadvantage of bed nets (OR = 0.39; 95% CI 0.23–0.78). The findings suggest that LLIN use is significantly influenced by social support and exposure to a malaria-related SBC home visit. The malaria community should thus further consider the importance of community outreach, interpersonal communication and social support on adoption of net use behaviors when designing future research and interventions.

In Southern Nigeria Loa loa Blood Microfilaria Density is Very Low Even in Areas with High Prevalence of Loiasis: Results of a Survey Using the New LoaScope Technology

Ivermectin treatment can cause central nervous system adverse events (CNS-AEs) in persons with very high-density Loa loa microfilaremia (≥ 30,000 mf/mL blood). Hypoendemic onchocerciasis areas where L. loa is endemic have been excluded from ivermectin mass drug administration programs (MDA) because of the concern for CNS AEs. The rapid assessment procedure for L. loa (RAPLOA) is a questionnaire survey to assess history of eye worm. If ≥ 40% of respondents report eye worm, this correlates with ≥ 2% prevalence of very high-density loiasis microfilaremia, posing an unacceptable risk of CNS-AEs after MDA. In 2016, we conducted a L. loa study in 110 ivermectin-naïve, suspected onchocerciasis hypoendemic villages in southern Nigeria. In previous RAPLOA surveys these villages had prevalences between 10% and 67%. We examined 10,605 residents using the LoaScope, a cell phone-based imaging device for rapidly determining the microfilaria (mf) density of L. loa infections. The mean L. loa village mf prevalence was 6.3% (range 0-29%) and the mean individual mf count among positives was 326 mf/mL. The maximum individual mf count was only 11,429 mf/mL, and among 2,748 persons sampled from the 28 villages with ≥ 40% RAPLOA, the ≥ 2% threshold of very high Loa mf density could be excluded with high statistical confidence (P < 0.01). These findings indicate that ivermectin MDA can be delivered in this area with extremely low risk of L. loa-related CNS-AEs. We also concluded that in Nigeria the RAPLOA survey methodology is not predictive of ≥ 2% prevalence of very high-density L. loa microfilaremia.