Bertram E. B. Nwoke

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.

The geographic distribution of onchocerciasis in the 20 participating countries of the African Programme for Onchocerciasis Control: (1) priority areas for ivermectin treatment

BackgroundThe African Programme for Onchocerciasis Control (APOC) was created to control onchocerciasis as a public health problem in 20 African countries. Its main strategy is community directed treatment with ivermectin. In order to identify all high risk areas where ivermectin treatment was needed, APOC used Rapid Epidemiological Mapping of Onchocerciasis (REMO). REMO has now been virtually completed and we report the results in two articles. The present article reports the mapping of high risk areas where onchocerciasis was a public health problem. The companion article reports the results of a geostatistical analysis of the REMO data to map endemicity levels and estimate the number infected.MethodsREMO consists of three stages: exclusion of areas that are unsuitable for the vector, selection of sample villages to be surveyed in each river basin, and examination of 30 to 50 adults for the presence of palpable onchocercal nodules in each selected village. The survey results and other relevant information were processed in a geographical information system. A panel of experts interpreted the data taking the river-based sampling into account and delineated high risk areas where the prevalence of nodules is greater than 20%.ResultsUnsuitable areas were identified in eight countries. In the remaining areas surveys were done in a total of 14,473 sample villages in which more than half a million people were examined. High-risk areas were identified in 18 APOC countries, ranging from small isolated foci to a vast contiguous endemic area of 2 million km2 running across seven countries. In five countries the high risk area covered more than 48% of the total surface area, and 31% to 48% of the population. It is estimated that 86 million people live in high risk areas in the APOC countries.ConclusionsThe REMO maps have played a significant role in onchocerciasis control in the 20 APOC countries. All high-risk areas where onchocerciasis used to be a serious public health problem have been clearly delineated. This led to the creation of community-directed treatment projects that by 2012 were providing annual ivermectin treatment to over 80 million people.

Endemicity of vesical schistosomiasis in the Ebonyi Benue River valley, South Eastern Nigeria

The investigation on the prevalence of patent and clinically severe infections with Schistosoma haematobium was carried out amongst inhabitants of Ebonyi Benue river valley, South Eastern Nigeria between August 2000 and June 2001. The inhabitants are predominantly farmers. Of the 3296 subjects examined from 15 randomly selected villages in the valley, 776 (23.5%) were excreting the eggs of S. haematobium in their urine. Infection rates varied between 18.9% and 30.6%. The severity of infection calculated by arithmetic mean egg counts (AMEC) and geometric mean egg counts (GMEC) varied significantly between the age groups and the villages (P < 0.05). The prevalence and severity of infection increased with age from 0 to 25 years and decreased thereafter. Symptoms associated with the disease include visible hematuria (63.1%), suprapubic pain (10.3%) and stranguary (9.9%). While 65 positive persons had more than one symptom, 64 of the positive persons had no noticeable symptoms. Visible hematuria showed moderate sensitivity and high specificity for the disease. Female genital schistosomiasis (FGS) of the lower reproductive tract was recorded in 19 females of child bearing age that complained of severe suprapubic pain. Eight snail species were recorded in the stagnant ponds and both Bulinus globosus and B. truncatus were infected with schistosome cercariae. The factors contributing to these observations and feasible control measures are discussed.

Dracunculiasis in the north eastern border of Ebonyi State, south eastern Nigeria

Between January and August 2000, a house-to-house survey of dracunculiasis was conducted in 15 communities along the north eastern border of Ebonyi State, south eastern Nigeria. Of the 3,777 subjects examined, 192 (5.1%) had active cases of guinea worm comprising 109 males (5.5%) and 83 females (4.6%). Infections were observed in all age groups. Of the 3,777 persons examined, 2,092 (55.4%) had ever been infected in the area. Protruding adult female Dracunculus medinensis worms were found predominantly on the lower limbs (80.2%), but also on the scrotum (9.4%), umbilicus (3.1%) groin (2.6%), buttocks (20.8%) and chest (1.6%). Prevalence of dracunculiasis had no significant sex, age and occupation related differences (P > 0.1). All the 47 stagnant ponds in the area were infested with cyclops while the 6 streams and 13 newly constructed community wells were free of cyclops. Of the five species of cyclopoid copepods found in the stagnant ponds, only Thermocyclops oblongatus nigerianus and Mesocyclops aequatorialis harboured guinea worm larvae. The efforts of the endemic communities, government and international organizations in guinea worm eradication in these areas are discussed.

The varied beneficial effects of ivermectin (Mectizan) treatment, as observed within onchocerciasis foci in south–eastern Nigeria

Abstract In the treatment of humans, ivermectin (Mectizan®), a semi-synthetic macrocyclic lactone, is now primarily used as a rapid microfilaricide. The drug has several other benefits, however, and these have recently been investigated in five states in south–eastern Nigeria, where there have been mass treatments with ivermectin, for the control of Onchocerca volvulus, for more than 10 years. Between the January and December of 2005, 3125 adult onchocerciasis patients (each aged ≥20 years and known to have at least one clinical sign of onchocerciasis) were enlisted, clinically examined and interviewed. Relevant data were collected in the interviews, using a structured, pre-tested questionnaire, and in personal and focus-group discussions. Overall, 612 (19.6%) of the subjects reported that they had had nodules that had disappeared following repeated doses of ivermectin, although only 83.8% of the 612 attributed their nodule clearance to ivermectin (the other 16.2% being unsure of the cause). A larger percentage of the subjects (24.6%) reported that they had expelled intestinal helminths following the last round of ivermectin treatment (i.e. been dewormed). Other side-benefits reported in the study were improved vision (11.7% of subjects), reversal of secondary amenorrhea (4.5%), increased appetite (22.3%), reduction in arthritic or other musculo–skeletal pain (7.9%), reductions in the severity of body itching (18.5%) and skin rash (17.3%), darkening of leopard skin (6.6%), improved libido in men (6.6%), and clearance of head lice (4.5%). If, via health education, the local communities could be made more aware of the side-benefits of ivermectin treatment, the sustainability of the on-going programme of community-directed treatment with ivermectin (CDTI) in south–eastern Nigeria would probably be improved.

Control of endemic dracunculiasis in Ebonyi state, south-eastern Nigeria.

A field study was carried out in Ozibo and the Ebonyi local government area of Ebonyi state, south-eastern Nigeria to determine the effectiveness of several intervention strategies in the control of endemic dracunculiasis in that area. During the initial study prior to the application of such measures, 14,421 subjects were examined. A total of 8,688 (60.2%) persons had either Dracunculus ulcers or emergent worms. Sex-related prevalence rates were 56.1% and 63.9% for males and females respectively. Age specific prevalence rates increased with age in males, whereas highest infection rates were found in females younger than 20 years. Twenty-eight months after the introduction of intervention strategies the prevalence rate fell by 85.1% to 9% (males: by 88.2% to 6.6%, females: by 83.0% to 10.8%). Reduction rates of more than 90% were observed in males aged 10 to 19 and in females aged 0 to 9 years. Intervention measures included systematic pond treatment, distribution or replacement of filters, intensive health education, provision of hand-dug wells, regular bore-hole installation/rehabilitation as well as active case detection, containment, management, and prompt reporting. Active involvement of the endemic communities, governments and the Global 2000 staff regarding the control efforts is a necessity towards the final eradication of the disease in the near future. The relationship between some of these intervention strategies and community development are highlighted.

Clinical and parasitological aspects of onchocercal skin diseases in Nigeria.

An assessment of onchocercal skin disease (OSD) conducted in 38 rural communities in the Imo River Basin, Nigeria, between March 1999 and September 2000, showed that depigmentation (DPM) was the most prevalent lesion in persons with skin microfilariae (mf) (26.3%), followed by chronic papular onchodermatitis (CPOD) (18.1%) and acute papular onchodermatitis (APOD) (15.5%). There was no significant difference (P>0.05) in sex-related prevalence of OSD. While CPOD, lichenified onchodermatitis (LOD) and DPM were more prevalent in subjects over 30 years old, APOD was associated more with those aged less than 30 years. OSD occurred with concomitant itching in nearly 50% of subjects. The geometric mean intensity of infection was 13 mf/mg per skin snip.

Human infections with Moniliformis moniliformis (Bremser 1811) Travassos 1915 in South-Eastern Nigeria

To control human infections with intestinal helminths, the residents of parts of Imo state, Nigeria, have recently been subjected to yearly, community-based, mass treatment with ivermectin (Mectizan®; Merck & Co.). Young children (aged < 5 years) and pregnant women are excluded but most other subjects are each given a single, oral dose of the drug (2, 6 or 12 mg for those who are 95.5-125.5, 125.6-149.9 or at least 150 em tall, respectively). To investigate the effect and usefulness of this treatment, each treated individual is asked to provide a stool sample to the drugdistribution team at least 36 h post-treatment. For the collection of stools, a coded, 2-litre container, with a wide opening and screw cap, is quarter-filled with 4% formalin solution and given to each treated person who agrees to provide a sample. The stool specimens are collected, taken to a central laboratory and checked for helminths, using either formolether concentration (King, 1973) or Kato smears (Martin and Beaver, 1968). Any adult worms encountered are removed, counted and identified. During the processing of stools from approximately 24 000 treated subjects, 19 of the samples were found to be contain the eggs and/ or adults of the acanthocephalan Moniliformis moniliformis (Bremser 1811) Travassos 1915. The eggs were identified as those of Mo. moniliformis on the basis of their small size (70-120 X 30-60 pm), their characteristic ovoid shape, and the triple-layered envelope (Ikeh et al., 1992). Of the 19 subjects found to be infected, each of whom had received only one treatment with ivermectin, two were aged < 10 years, eight were between 11 and 20 years and the other nine were older ( > 20 years). Most (11) were male, and all were either hired palm-wine tappers (nine) or farmers (10). Seven of the cases were symptomatic, with tinnitus/ dizziness (three cases), general stomach pains (two cases), watery stools (one case), or (unexplained) abdominal discomfort around the umbilicus (one case). All 19 infections were treated, apparently successfully, with further doses of ivermectin. Moniliformis moniliformis has a cosmopolitan distribution, rodents being the usual definitive hosts and cockroaches and beetles the (proven) intermediate hosts (Miyazaki, 1991). Human infection with this parasite appears to be rare. However, the possible epidemiological significance of such infection was recognised more than a century ago. It was then that S. Calandruccio experienced diarrhoea, acute abdominal pain, exhaustion, somnolence and violent ringing in his ears and head 19 days after he infected himself experimentally with the acanthocephalan (Grassi and Calandruccio, 1888). About 15% of the coprolites, from a grain-eating prehistoric man, found in a cave in Utah (U.S.A.) contained Moniliformis eggs (Moore et a/., 1969). In Iran, Moayedi et a/. (1971) found a 4-month-old boy, who had had repeated episodes of watery stool, accompanied by irritability, coughing and sweating, to be infected with Mo. moniliformis. Al-Rawas et a/. (1977) documented the first recognised case of infection with this parasite in an Iraqi child. However, it was another 25 years before the first report of human infection with Mo. moniliformis in Nigeria. This infection was in a 45-year-old man who presented at the health clinic of the University of Jos, in northern Nigeria, complaining of general body weakness, occasional giddiness and (curiously, given the similar observation in the present study) intermittent burning sensations around the umbilicus (Ikeh et a/., 1992). This case was treated, again apparently successfully, with four tablets of niclosamide (Yomesan®; Bayer) given as a single dose, although no adult Mo. moniliformis were ever recovered. In south-eastern Nigeria (in households and range lands in the rural communities of

Onchocerciasis in Imo state, Nigeria (2): the prevalence, intensity and distribution in the upper Imo river basin.

Human infection with Onchocerca volvulus was investigated in 13 rural communities in the Upper Imo River basin, Imo State, Nigeria between March 1997 and December 2000 using the skin snip method. Of the 3,311 persons examined, 889 (26.8%) had microfilariae. There were significant differences between communities in microfilariae prevalence and intensity of infection (P < 0.05). Sex infection was similar in males (26.8%) and females (26.9%); whereas farmers (46.6%) and fishermen (28.4%) were more affected than people in other occupations. The proportion of infected persons increased with age coinciding with the period when most clinical signs manifest. A significant proportion of the 889 persons with positive microfilariae skin biopsy had musculoskeletal pain (57.1%). Thirty-four (47.2%) of the 72 epileptics identified had positive skin biopsy in addition to other manifestations. The present findings show that onchocerciasis is a public health problem in the area. The use of ivermectin has reduced the incidence of the disease when compared with data from the pre-ivermectin era. This shows that Community Directed Treatment with Ivermectin (CDTI) campaign is successful and should be sustained until onchocerciasis is eliminated as a public health problem in the area.

Awareness, perceptions and intent to comply with the prospective malaria vaccine in parts of South Eastern Nigeria

BackgroundThere are potentials of a malaria vaccine being developed sooner than expected. While focus is more on the development of a vaccine, less attention has been paid on the extent to which such vaccines could be well accepted and the readiness among caregivers to comply with its use in order to achieve the effectiveness of the vaccine in the malaria endemic areas. Compliance rates are influenced by the level of awareness, as well as the perception of the population. This cross-sectional study was aimed at assessing the awareness, perceptions and intent to comply with the prospective malaria vaccine by caregivers in Owerri West, South Eastern Nigeria.MethodsStructured pretested questionnaires were used to collect data from 500 randomly selected consenting care givers (mostly mothers). Items used to assess the intent to comply with the vaccine include willingness to accept and use the vaccine, and allow children to be vaccinated.ResultsThe study found that awareness of malaria as a public health problem was high (89.8%), but awareness about a prospective malaria vaccine was not high (48.2%). Up to 88.2% of respondents showed positive perception towards the vaccine, of which 65.2% had strong positive perception. The study found high level of intent to comply with the prospective malaria vaccine among the study group (95.6% positive). Significant association was established between caregivers perception and intent to comply with the prospective malaria vaccine (χ2 = 144.52; p < 0.0001).ConclusionsWhile malaria vaccine adoption is likely to be a welcome development in South Eastern Nigeria, proper consideration should be given to factors that are likely to influence people’s perceptions about vaccines in the plans/process of malaria vaccine development and vaccination programmes.