Seasonal biting pattern of Simulium damnosum s.l and its implications on onchocerciasis treatment with ivermectin

BACKGROUND

The current control strategy adopted by African Programme for Onchocerciasis Control (APOC) is the mass distribution of ivermectin in all endemic areas for between 12-15 years. One of the major obstacles of the strategy, is the ability of the fly to migrate long distances and this brings about the possibility of flies migrating from uncontrolled areas to controlled areas.

OBJECTIVE

To assess the impact of annual ivermectin treatment of onchocerciasis and to ascertain the seasonality of transmission and its impact on the current control strategy in the forest zone around a dam in Southern Nigeria.

METHODS

A 36 x 11-hour entomological survey was carried out in the study area. Simulium damnosum s.l were caught using two human baits from 07.00 hours-18.00 hours, three days of every month for 12 months according to the method of Walsh et al. The head, thorax and abdomen of each insect were dissected separately. Catches were made from dawn to dusk.

RESULTS

Catches yielded a total of 2,807 female S. damnosum s.l. Higher mean biting rates (2,486 flies/man/year) occurred during the dry season. The mean monthly distribution of parous flies also showed distinct seasonality with preponderance of parous flies during the dry season (61.8%) as compared to the rainy season (38.6%). Flies harbouring developing and infective larvae were observed during the dry season in October and December when the monthly transmission potential recorded was 31 larvae/man/month. This dropped to 28 larvae/man/month and 25 larvae/man/month in January and February respectively. An annual transmission potential of 115 larvae/man/year was recorded.

CONCLUSION

In spite of the ivermectin treatment in the area at the time of study, the transmission of Onchocerca volvulus continued unabated in the area with a higher transmission in the dry season than the rainy season. The distribution of ivermectin should be intensified through improved coverage while other control measures may be necessary during the dry season which is the peak of transmission in the area.

Identification of three members of the Simulium damnosum (Diptera Simuliidae) group in South Western Nigeria

Identification of the specific Simuliium species at play in the transmission of Onchocerca volvulus is important because it helps to explain the epidemiology and clinical presentation of the disease and guides in monitoring of long term impact of ivermectin treatment on onchocerciasis transmission. The study therefore sought to use molecular markers for vector identification. A combination of Polymerase Chain Reaction (PCR) assay and Restriction fragment Length polymorphism (RFLP) was used to identify members of Simulium damnosum complex in forest area of south western Nigeria. The results revealed the presence of three members of the Simulium damnosum complex: S. yahense, S. sirbanum and S. damnosum ss. S. yahense was the predominant and major vector in the study sites. This provides baseline data for future monitoring vector of human onchocerciasis in the area.

A pilot study to evaluate malaria control strategies in Ogun state, Nigeria

With limited evidence of decreases in malaria-related mortality and morbidity, and nearly half the time to the 2010 deadline of Roll Back Malaria (RBM) targets now past, we conducted this study to assess the awareness, accessibility and use of malaria control strategies among at-risk groups within the context of RBM in Nigeria. It was a descriptive, cross-sectional pilot study of 34 registered women attending antenatal clinics and 34 mothers of children less than five years old, using a questionnaire in a malaria holo-endemic community of Ogun State, Nigeria. Results showed that 14.7% and 16.2% of all respondents interviewed were aware of the home management of malaria (HMM) program (17.6% of mothers of children under five years vs. 11.8% of pregnant women) and the change in policy on malaria treatment (23.5% of mothers of children under five years vs. 8.8% of pregnant women) respectively. Younger respondents knew more about HMM than older ones (p <.05). Most (63.2%) of the 68 respondents (64.7% of mothers of children under five years vs. 61.8% of pregnant women) interviewed knew about insecticide treated nets (ITNs); however, only 22.1% were using the treated material. Reasons given by those not using ITNs included: they did not know about ITN prior to the interview (43.3%(, they had no money (41.5%) and they did not know where to get it (7.6%). Only 5.8% of mothers of children less than five years old, and none of the pregnant women, had taken the new combination drug. Eight (23.5%) of the 34 pregnant women interviewed knew about intermittent preventive treatment of malaria for pregnant women (IPT), while two (25.0%) of these eight women had received a preventive treatment dose. The results of this pilot study showed that efforts need be intensified to make adequate information and materials relating to the different malaria control strategies more available and accessible at the community level to achieve and sustain the RBM goals, both in Ogun State and in Nigeria in general. However, a larger study is needed to provide more generalized findings.

Willingness to seek HIV testing and counseling among pregnant women attending antenatal clinics in Ogun State, Nigeria

HIV counseling and testing (CT) is slowly being introduced as one of several key components of the comprehensive package of HIV/AIDS prevention and care in Nigeria, particularly in the prevention of mother-to-child transmission of HIV (PMTCT). A cross-sectional survey of 804 women attending antenatal clinics (ANC) in Ogun State, Nigeria was done using questionnaires to assess their willingness to seek and undergo CT and know the determinants. Focus group discussions were also held in the general community: 84.3% of respondents believed in AIDS reality, while 24.3% thought they were at risk of HIV infection. Only 27% knew about MTCT, while 69.7% of 723 who had heard of HIV/AIDS did not know about CT. Only 71 (8.8%) had thought about CT and 33 (4.5%) mentioned HIV testing as one of antenatal tests. After health education on CT, 89% of the women expressed willingness to be tested. Their willingness for CT was positively associated with education (p < 0.05), ranging from 77% (no education) to 93% (post-secondary). More of those with self-perceived risk expressed willingness to test for HIV (p < 0.05). Those willing to be tested had a higher knowledge score on how HIV spreads than those not willing. Multiple regressions identified four key factors that were associated with willingness for CT: increasing educational level; not fearing a blood test; perception that the clinic offered privacy; and perceptions of higher levels of social support from relatives and peers. Those unwilling or undecided about CT expressed strong fear of social stigma/rejection if tested positive. The results provided insights for planning promotional programs and showed that not only are IEC efforts needed to boost knowledge about HIV/AIDS, but that change in clinic setting and community are imperative in creating supportive environment to encourage uptake of CT services.

Sociocultural aspects of mass delivery of praziquantel in schistosomiasis control: the Abeokuta experience

BACKGROUND

Schistosomiasis is a public health problem in Nigeria. Although there is an ongoing national program for its control, disease control programs in other countries have shown the need to understand the sociocultural aspects of disease transmission, prevention, and treatment in endemic communities before control efforts are undertaken.

OBJECTIVE

To describe sociocultural factors that influence the distribution process of praziquantel for the mass treatment of schistosomiasis infection.

METHODS

Data for the study were collected through focus group discussions held separately with adult males and females, male and female adolescents (13-19 years), and male and female children (5-12 years). In-depth interviews were similarly held with the drug distributors of praziquantel for mass treatment and with community/opinion leaders of six hyperendemic communities in Ogun State, Southwest Nigeria on mass treatment using praziquantel. These focus group discussions and in-depth interviews were held both before and following the drug distribution. The data were analyzed using the textual analysis program, Textbase Beta.

RESULTS

Following a 3-week period of mass treatment in six communities, we observed an increased awareness of rivers/streams as a source of schistosomiasis. In addition, the communities reported overwhelming support for the mass treatment after receiving treatment. The reasons for this acceptance appear to include the perceived efficacy of praziquantel against the disease and its availability free of charge. The drug's distributors adhered to the originally specified systems-based protocol for mass treatment in only two of the six communities. The systems-based protocol adhered to strict distribution through primary health centers and schools. The four other communities used a community-based approach for mass treatment with praziquantel and attained greater coverage of treatment as a result.

CONCLUSION

Obtaining community support and involvement before the implementation of mass treatment of schistosomiasis with praziquantel contributes to an effective treatment strategy for this disease. A detailed assessment of a community's health needs, before the initiation of the control efforts against endemic infections, should be undertaken.

Herbal remedy in the treatment of malaria: cross sectional survey of residents of Lagos State, Nigeria

Semi structured questionnaires. designed to capture information on the type. composition, method of preparation. dosage, mode of administration. and frequency of use of herbal preparations in malaria treatment, were administered to 1,593 adults of the 3 main ethnic groups and a forth group comprising other smaller ethnic groups designated as "others", all resident in Lagos metropolis in a cross sectional survey. The 1,593 respondents were made up of 892 males and 701 females and their ages ranged from 19 to 60 years. A high percentage in all the ethnic groups especially the Yorubas admitted to the use of herbs in treating malaria [Yoruba (69%), Hausa (47%). others (32%) and Igbo (30%)1. Effectiveness of herbs in treating malaria episodes featured as the major factor for their use. as claimed by the majority (>50%) of the respondents in each of the ethnic groups, while cost consideration was the next most important factor. Other factors mentioned included the absence of side effect in herbal use. to avoid the itchy side effect and ineffectiveness of chloroquine and some other anti-malarials. An appreciable percentage across the ethnic groups had no idea of the constituents of the herbal remedies they use for treating their malaria episodes since they buy these from traditional herbalists. Varied combinations of these herbs in combination with different types of fruits and other substances are claimed to be used, the main ones of which are Azardiracha indica and pineapple. A large majority of respondents in all the ethnic groups claimed to use the same herbs for the treatment and prevention of malaria and great improvement is experienced after use [Hausas (90%). Igbos (83%). Yorubas (77%) and the others (88%)]. There is usually no specific dose or dose regimen. however a high proportion in all the ethnic groups use herbal preparation thrice a day and a few of the respondents take unspecified measures at arbitrary intervals. The lack of standards in the use of these herbal preparations needs to be urgently addressed especially as use continued until the malaria symptoms and signs are deemed to have disappeared. There is also need to standardize the usage of herbs if they are to play a significant role in malaria prevention and treatment.

Willingness to pay for praziquantel treatment in a hyperendemic community of Ogun State, Nigeria

BACKGROUND

Schistosomiasis is highly endemic in Nigeria. However, very little is known about the usage and social marketing of praziquantel in the control of schistosomiasis in endemic communities and on the persons willingness to pay for the drug to support its extensive use and thus aid control efforts in Nigeria.

OBJECTIVE

The study examined the willingness of people in a hyperendemic community, to pay for treatment with praziquantel before and after provision of the drug, with a view to assess the feasibility of achieving widespread coverage.

METHODS

Data were collected through focus group discussions among household heads and other adult family members and through the use of a questionnaire to survey household heads in Imala-Odo, a community hyperendemic for schistosomiasis, in southwest Nigeria. The main outcome measure was the respondents' willingness to pay for schistosomiasis treatment.

RESULTS

The results showed that in contrast to the 92.3% of respondents who expressed willingness to buy the drug in the preintervention study, only 46.5% actually purchased the drug during intervention for the treatment of their infected household members. The respondents' level of education, occupation, and income influenced their willingness to pay (P<.05). Statistical tests showed that those willing to pay for treatment had a higher income score than those unwilling to do so. Most respondents preferred their community head and reliable persons chosen by the community as convenient outlets for drug distribution. The number of household members respondents were willing to treat increased from 4 to 6 at N320.00 (US $2.52) in the preintervention and postintervention phases, respectively. Gender factor was found to influence the respondents' perceived average treatment cost; the females wanted N300.00 (US $2.36) against N100.00 (US $0.79) among the males.

CONCLUSION

Efforts need to be made and sustained to ensure that all families can afford to praziquantel drug to achieve the ultimate goal of controlling the infection in endemic communities of Nigeria.

Effectiveness of different approaches to mass delivery of praziquantel among school-aged children in rural communities in Nigeria

Schistosomiasis is hyperendemic in Nigeria. The national policy on schistosomiasis control has adopted praziquantel as the main drug of use in the control strategy aimed at reducing morbidity. However, the best delivery channel for praziquantel in schistosomiasis control in Nigeria is yet to be determined. This study assessed different channels for praziquantel delivery in a mass treatment effort. Three groups, each of two communities, were assigned to one of the following three channels: health facility (HF), school, and community for mass delivery of praziquantel to school-aged children. Distributors were trained on all aspects of praziquantel distribution and sufficient praziquantel tablets were provided for the drug distribution within 3 weeks following which an evaluation of the drug distribution by the different treatment channels was conducted. Overall, the community channel of delivery achieved the best coverage of 72.2% (range: 69-73%) compared to 44.3% (range: 39.5-62%) and 28.5% (range: 26.3-74.5%) for the HF and school channels, respectively. Community channel of praziquantel delivery as shown in this study ensures good coverage of both in and out-of-school children.

Identification of the forest strain of Onchocerca volvulus using the polymerase chain reaction technique

Annual mass treatment with ivermectin for 12-15 years in endemic communities is the control strategy adopted by the African Programme for Onchocerciasis Control (APOC) for the control of onchocerciasis in Nigeria. This long-term treatment necessitates the use of Polymerase Chain Reaction (PCR) for the proper identification of the Onchocerca species and strains in endemic areas and also for monitoring recrudescence of infection in areas where infection has been controlled. This study, which forms part of a larger study on transmission of onchocerciasis identifies the Onchocerca volvulus strain in Ondo state using the Polymerase Chain Reaction (PCR) technique. Deoxyribonucleic acid (DNA) was extracted from the adult worm of Onchocerca parasite using the glass bead method of extraction. The repeated sequence family present in the genome of the parasite designated as 0-150bp was amplified by the polymerase chain reaction (PCR). The amplified parasites produced significant products visible as bands in a 2% agarose gel stained with ethidium bromide. Hybridization of the PCR products with specific DNA probe identified the products as forest strain of Onchocerca volvulus. The epidemiological implication of this is that there would be more of the skin lesions and low blindness rate in the area.

Endemicity of onchocerciasis in some local government areas of Niger state

The established method of justifying the need for ivermectin delivery to a community is the use of Rapid Assessment Method (RAM). This method involves the clinical examination of 50 adult males, who have been resident in the community for at least five years, for onchocercal nodules and leopard skin. The values obtained for these indices will guide the classification of such a community as being hypoendemic, mesoendemic or hyperendemic. Those that fall within mesoendemic and hyperendemic category onchocerciasis qualify for ivermectin delivery. This study was carried out to determine the endemicity level of onchocerciasis in 74 communities of 8 Local Government Areas (LGAs) of Niger state to justify their inclusion or otherwise in the ongoing state wide mass treatment for onchocerciasis using ivermectin. The communities were selected using the Geographical Information System (GIS) data and following the World Health Organization (WHO) guideline for RAM. A total of 3000 subjects were examined comprising of 2395 (79.8%) males and 605 (20.2%) females. None of the LGAs, based on overall prevalence for nodules qualify for mass treatment with ivermectin. However the study identified communities within some of these LGAs that were mesoendemic for onchocerciasis and thus qualified for mass treatment with ivermectin.

Control of urinary schistosomiasis: an investigation into the effective use of questionnaires to identify high-risk communities and individuals in Niger State, Nigeria

Schistosomiasis is a public health problem in Nigeria. Although there is a national programme for its control, there is the need for reliable and simple means of rapidly diagnosing communities to provide a detailed map on the distribution of the disease in the country, in order to prioritize control activities, as well as to monitor the effectiveness of control operations. A rapid assessment technique using school questionnaires was tested in Borgu Local Government Area (LGA), Niger State, north-western Nigeria. Following a series of focus group discussions, the questionnaires were adapted before they were administered through the school system to 60 primary schools in Borgu LGA. Correctly completed questionnaires were returned from 58 schools (97%) within 4 weeks. Questionnaires were validated by reagent stick tests performed by trained teachers. Their results proved to be reliable compared to those obtained by our research team in 20 randomly selected schools. Overall prevalences of microhaematuria at 1+ and 2+ levels were 45.7% and 27. 1%, respectively. Highly significant correlations were obtained between school prevalence of microhaematuria and reported schistosomiasis, as well as reported blood in urine. The diagnostic performance of the questionnaires at the 2+ level of microhaematuria was very good. The design of our study also allowed data analysis on an individual level, and multivariate analysis revealed highly significant odds ratios for reported schistosomiasis and reported blood in urine to detect an individual with urinary schistosomiasis. Our results are in good agreement with reports from other African countries, and questionnaires can be recommended for rapid identification of communities at highest risk of urinary schistosomiasis in Nigeria, so that scarce resources of the national control programme can be used most effectively.

Infectivity and transmission dynamics of simulium damnosum s. 1 around Owena dam (Ondo State)

A twelve month study on the infectivity and transmission dynamics of simulium damnosum s.1 around Owena dam was conducted as part of a longitudinal study of onchocerciasis in the community living in the vicinity of the dam. A total of 3,133 flies (49.6% nilliparous, 50.4% parous) were caught during the period of study and dissected. The annual biting rate per year was recorded as 33,663 flies while the parous biting rate was recorded as 16,780 for these flies. 0.4% of the flies were infected with Onchocerca volvulus larvae while 0.3% of these had the infective larvae. However 0.3% of the nulliparous flies were found to be infected with mermithid larvae and 0.5% with trematodes. The biting activity of the fly was observed to be bimodal with a small peak in the morning hours (10.00-11.00 hours) and a more pronounced peak in the evening (16.00-17.00 hours). An annual transmission potential of 109 larvae per man per year was recorded with 64% of the infection being recorded during the early dry season when the parous rate was very high. The implications of these findings to the study area are discussed.

The diagnostic potential of three indirect tests for urinary schistosomiasis in Nigeria

Schistosomiasis is one of the major parasitic infections of man in the tropical and subtropical areas of the world. Diagnosis of the disease is usually based on microscopic detection of eggs in excreta which is both laborious and time consuming. In Nigeria, the Government's emphasis on the control of the disease dictates the need for a simple, fast, reliable and affordable diagnostic test for the identification of infected communities and detection of infected persons. Three indirect diagnostic tests for urinary schistosomiasis: interview technique, visual examination for macrohaematuria and the use of a chemical reagent strip were employed in screening 1056 individuals of the Kainji Lake area of Nigeria for urinary schistosomiasis, using haematuria as the disease indicator. The sensitivity of the three tests were determined using the filtration (egg counting) technique as the reference test. The sensitivity of the reagent strip test was 69.0% and 44 and 38% for the interview technique and visual examination respectively. The reagent strip test was particularly useful for screening children (5-19 years old). The implication of these findings are discussed.

Impact of guineaworm disease on agricultural productivity in Owo local government area, Ondo state

Of the 500 Cocoa farmers infected with guineaworm in Amurin, 74.3% of the farmers were incapacitated for 3 months without going to their farms while 25.7% mostly those who sought the orthodox form of treatment were incapacitated for about 4 weeks. This resulted in the loss of 9,566 bags of the potential harvest of the farmers which translates to N2,442,000.00 for the period. The sustantial part of this loss was from cocoa (N1, 570,000.00), a major export crop in Nigeria. The losses experienced were as a result of inability to plant and supervise the farm. An average of 45,000 mandays were lost due to guineaworm infection at a value of N54.27 k per individual for incapacitation for a day and a farmer infected with guineaworm loses 19 bags of his potential harvest within the infection duration, which translates to N4,884.00. Guineaworm disease is a major preventable cause of agricultural work loss and significant impediment to agriculture, the dominant occupation in Nigeria, which implies that guineaworm disease poses large threat to food availability.