Epidemiological evaluation of onchocerciasis along Ogun River System, southwest Nigeria.

BACKGROUND & OBJECTIVE: Epidemiological studies were carried out to assess the prevalence and community microfilarial load (CMFL) of onchocerciasis after repeated annual treatment with ivermectin along Ogun river System, southwest Nigeria. METHOD: Skin snips were taken from consented participants in 11 selected communities along the River system. The microfilarial load of the community was estimated. RESULTS: The prevalence and CMFL varied significantly in the communities (p <0.05). The prevalence of onchocerciasis ranged from 19.1 to 45.6%, while the CMFL ranged from 0.11 to 1.03 microfilariae per skin snip. The CMFL recorded was <5 microfilariae per skin snip, i.e. recognized by WHO as threshold value in certifying the communities to be free of onchocerciasis as public health problem, thus, signifying the possibility of onchocerciasis elimination in the study area. CONCLUSION: Efforts should therefore be intensified to achieve improved ivermectin coverage and compliance in annual ivermectin treatment in order to completely eliminate onchocerciasis as a public health problem in the studied communities.

Population dynamics of indoor sampled mosquitoes and their implication in disease transmission in Abeokuta, south-western Nigeria.

BACKGROUND & OBJECTIVES: A longitudinal study was carried out to investigate the species composition, seasonal abundance, parity and feeding preference of indoor sampled mosquitoes in Abeokuta, south-western Nigeria. METHODS: The mosquitoes were sampled weekly from five stratified locations using Center for Disease Control (CDC) light-traps between August 2005 and July 2006. The mosquitoes were examined for abdominal condition and dissected for age composition. Microscopic and precipitin techniques were also employed for the determination of host blood source. RESULTS: A total of 2969 mosquitoes which belong to 10 species of mosquitoes were collected during the study period. Mansonia africana (35.65%) constituted the most abundant species followed by Culex quinquefasciatus (32.23%) and Anopheles gambiae complex (13.52%). Other species in decreasing order of abundance were Coquilletidia maculipennis (8.2%), Aedes albopictus (5.9%), Ae. aegypti (1.93%), M. uniformis (1.81%), Cx. duttoni (0.25%), Cx. tigripes (0.25%) and An. funestus (0.25%). Seasonal abundance revealed a significant difference (p <0.05) in the population of mosquito vectors collected during the wet season as compared to the dry season and their abundance was positively correlated with rainfall. The results showed that the majority of the vector species collected were unfed and nulliparous. Moreover, the blood meal test was positive for human blood. CONCLUSION: The preponderance of mosquitoes observed in the study is of public health concern since they serve as vectors of most tropical diseases including malaria.

Morphometric studies on Culex quinquefasciatus and Mansonia africana (Diptera: Culicidae) in Abeokuta, south-western Nigeria.

Some of the important mosquito species are generally sympatric in terms of their geographical distributions, and are difficult to identify based solely on examination of adult females using the available morphological keys. In this study, adult mosquitoes were collected indoors in Abeokuta in south-western Nigeria between August 2005 and July 2006 using Center for Disease Control light traps. The objective was to investigate possible morphological differences in populations of Culex quinquefasciatus and Mansonia africana. Six morphological characters namely, wing length, antennal length, proboscis length, foreleg length, mid leg length and hind leg length were measured in the two species. A total of 868 Cx quinquefasciatus and 962 M. africana were collected during the study period. The mean length was observed to be higher in most characters during the wet season than the dry season but the variation was not statistically significant (P > 0.005). In M. africana, the antennal length, proboscis length, foreleg length and midleg length showed one peak each. The wing length exhibited three peaks while hind leg length showed two peaks. For Cx quinquefasciatus, the antennal length, proboscis length, foreleg length, mid leg length and hind leg length indicated one peak. The wing length however showed three peaks. Each of the peaks observed in wing length and hind leg length of M. africana and wing length of Cx quinquefasciatus was assumed to be a specific population. The coefficient of differences (CDs) for each population indicated the presence of three populations in M. africana (CD > 1.28). However, the hind leg length showed that the two populations were the same (CD < 1.28). Three populations were also obtained from CD for wing leg length of Cx quinquefasciatus (CD > 1.28). Other characters indicated the presence of only one population. The results therefore underscore the need to investigate the status of the two species in relation to species complex.

Mosquito larval habitats and public health implications in Abeokuta, Ogun State, Nigeria.

The larval habitats of mosquitoes were investigated in Abeokuta, Nigeria in order to determine the breeding sites of the existing mosquito fauna and its possible public health implications on the residents of the City. The habitats were sampled between August 2005 and July 2006 using plastic dippers and a pipette. The habitats were grouped as ground pools/ponds, gutters/open drains, tyres, domestic containers and treeholes/ leaf axils. Ten species of mosquitoes were encountered in the five habitats namely Mansonia africana, M. uniformis, Culex quinquefasciatus, Aedes aegypti, Ae. albopictus, Ae. vittatus, Cx tigripes, Anopheles gambiae s.l., An. funestus and Eretmapodite clnysogaster. Ae. aegypti bred in all the habitats sampled while Cx quinquefasciatus bred in four habitats except tree holes/leaf axils. An. gambiae s.l and Ae. albopictus occurred in three habitats while other species bred only in one or two habitats. Ground pools and domestic containers recorded the highest number of species followed by gutters/open drains. Tree holes/leaf axils was the least preferred habitat with the lowest number of species occurrence. However, statistical analysis revealed non-significant difference in species occurrence in the five habitats. The availability of the habitats to support the breeding of Aedes, Culex and Anopheles, which are known vectors of urban yellow fever, lymphatic filariasis and malaria suggest that the residents ofAbeokuta City are at risk of mosquito-borne diseases. It is important that residents of the City are enlighten on the environmental factors that contribute to mosquito breeding and that the Government should institute proper sanitation measures to reduce mosquito breeding sites.

Perceptions and home management practices of malaria in some rural communities in Abeokuta, Nigeria.

A survey was carried out in five rural communities that enjoy agricultural extension services from the University of Agriculture Abeokuta. Questionnaires and focus group discussions (FGDs) were used to assess perceptions and home management practices of malaria infection. The inhabitants considered malaria (which they refer to as "Iba Otutu") has the least dangerous of other types of common fever such as yellow fever and typhoid fever. A vast majority of the respondents (73%) attributed malaria infection to doing of strenuous jobs in the hot sun, while only 11.7% attributed it to mosquito bites. Hunger, eating or drinking of contaminated food or water were other sources of malaria infection mentioned by the respondent. During the FGDs, another source of infection of malaria identified was excessive exposure to heat of fire used in frying cassava (garri), therefore those frying garri and those spreading cassava flakes in the sun were identified as most vulnerable to malaria infection. During the FGD, high level of malaria infection in children was attributed to children playful activities in the sun. It is believed that malaria infection will occur even without mosquito bites but with exposure to these other factors especially the intense heat of the sun. Respondents showed good knowledge of malaria symptoms even in infants and children. However, in the event of malaria infection consumption of herbal preparations is the first line of treatment. Drug hawkers that sell modern drugs in the communities were mainly consulted for malaria treatment. The antimalarial drugs bought were often wrongly used and none of the respondents were aware of the current trend in malaria management with modern drugs. Hospital visitation is usually after many days of persistent illness without improvement despite all forms of self medication. The main measure used against malaria vectors was insecticide coils (74.6%). None of the respondents used insecticide treated net (ITN). Distance, cost and poor quality of hospital treatment were reasons for refusal to seek proper medical care. Health education and improved health care services are recommended for these farmers in order for them to be able to translate extension services provided into maximum agricultural yields.

Traditional birth home attendance and its implications for malaria control during pregnancy in Nigeria.

A longitudinal survey was carried out to assess prevalence of malaria infection among attendees of a traditional birth home (TBH) in the metropolis of Abeokuta, Nigeria. Malaria prevalence was 62.4%, and various degrees of anaemia were recorded in 80.3% of pregnant women. Patronage by pregnant teenagers was 10.8%, with all of them anaemic and 73.9% infected with malarial parasites. Knowledge of malaria transmission and prevention were generally poor, with the emphasis placed on exposure to direct rays and heat from the sun. Avoidance of the sun's heat was therefore considered to be an effective preventive measure; another was the consumption of specially prepared and packaged herbal tea, which the pregnant women were expected to drink daily. Only 36.3% of the women associated malaria infection with mosquito bites. The use of insecticide-treated nets (ITNs) was not recorded among the women, although a large proportion (91.3%) showed a willingness to buy ITNs. The cost of receiving antenatal care at the TBH was higher than that in public hospitals. Patronage of TBHs was observed to be linked more with cultural beliefs than poverty. This study suggests that there is a need to extend malaria control interventions to women attending TBHs.

Mosquito larval habitats and public health implications in Abeokuta, Ogun State, Nigeria

Abstract: The larval habitats of mosquitoes were investigated in Abeokuta, Nigeria in order to determine the breeding sites of the existing mosquito fauna and its possible public health implications on the residents of the City. The habitats were sampled between August 2005 and July 2006 using plastic dippers and a pipette. The habitats were grouped as ground pools/ponds, gutters/open drains, tyres, domestic containers and treeholes/ leaf axils. Ten species of mosquitoes were encountered in the fi ve habitats namely Mansonia africana, M. uniformis, Culex quinquefasciatus, Aedes aegypti, Ae. albopictus, Ae. vittatus, Cx tigripes, Anopheles gambiae s.l., An. funestus and Eretmapodite clnysogaster. Ae. aegypti bred in all the habitats sampled while Cx quinquefasciatus bred in four habitats except tree holes/leaf axils. An. gambiae s.l and Ae. albopictus occurred in three habitats while other species bred only in one or two habitats. Ground pools and domestic containers recorded the highest number of species followed by gutters/open drains. Tree holes/leaf axils was the least preferred habitat with the lowest number of species occurrence. However, statistical analysis revealed non-signifi-cant difference in species occurrence in the fi ve habitats. The availability of the habitats to support the breeding of Aedes, Culex and Anopheles, which are known vectors of urban yellow fever, lymphatic fi lariasis and malaria suggest that the residents of Abeokuta City are at risk of mosquito-borne diseases. It is important that residents of the City are enlighten on the environmental factors that contribute to mosquito breeding and that the Government should institute proper sanitation measures to reduce mosquito breeding sites

MONRATE: A descriptive tool for calculation and prediction of re-infection of Ascaris lumbricoides (Ascaridida: Ascarididae)

The study presents an interactive descriptive tool (MONRATE) for calculating and predicting reinfection rates and time of Ascaris lumbricoides following mass chemotherapy. The implementation was based on the theoretical equation published by Hayashi in 1977, for time-prevalence: Y=G [1-(1-X)N-R] as modified by Jong-Yil in 1983. Using the Psuedo-Code of the MONRATE tool, the calculated monthly reinfection rates (X) for the LGAs are (names are locations in Nigeria in a region predominately populated by the Yoruba speaking tribes of Nigeria whose traditional occupations are agriculture and commerce): Ewekoro (1.6 %), Odeda (2.3 %), Ado-odo/Otta (2.3 %), Ogun Waterside (3.8 %) and Obafemi/Owode (4.2 %). The mathematical mean of ‘X’ values in the study areas for Ogun State was 2.84. The calculated reinfection time (N months) for the LGAs are varied such as Ado-odo/Otta (12.7), Ogun Waterside (21.8), Obafemi/Owode (22.92), Odeda (25.45), and Ewekoro (25.9). The mean value for N in Ogun State was 21.75. The results obtained from MONRATE were compared with those obtained using the mathematical equation and found to be the same. Rev. Biol. Trop. 55 (3-4): 755-760. Epub 2007 December, 28.

Se presenta una herramienta descriptiva e interactiva (MONRATE) para calcular y predecir las tasas y tiempo de reinfección con Ascaris lumbricoides tras un tratamiento de quimioterapia. Nos basamos en la ecuación propuesta por Hayashi en 1977 para el tiempo de prevalencia: Y=G [1- (1-X)N-R], según la modificó Jong-Yil en 1983. Utilizando el código Psuedo de la herramienta de MONRATE, las tasas de reinfección mensuales (X) para varios sitios de Nigeria, África, son: Ewekoro (1.6 %), Odeda (2.3 %), Ado-odo/Otta (2.3 %), Ogun Waterside (3.8 %) y Obafemi/ Owode (4.2 %). El promedio matemático de los valores de "X" en el área de estudio del Estado de Ogun fue 2.84. El tiempo de reinfección calculado (N meses) para LGAs es variado: Ado-odo/Otta (12.7), Ogun Waterside (21.8), Obafemi/Owode (22.92), Odeda (25.45) y Ewekoro (25.9). El valor promedio para N en el Estado de Ogun fue 21.75. Los resultados del programa MONRATE son iguales a los producidos por la ecuación.

MONRATE: A descriptive tool for calculation and prediction of re-infection of Ascaris lumbricoides (Ascaridida: Ascarididae).

The study presents an interactive descriptive tool (MONRATE) for calculating and predicting reinfection rates and time of Ascaris lumbricoides following mass chemotherapy. The implementation was based on the theoretical equation published by Hayashi in 1977, for time-prevalence: Y=G [1-(1-X)(N-R)] as modified by Jong-Yil in 1983. Using the Psuedo-Code of the MONRATE tool, the calculated monthly reinfection rates (X) for the LGAs are (names are locations in Nigeria in a region predominately populated by the Yoruba speaking tribes of Nigeria whose traditional occupations are agriculture and commerce): Ewekoro (1.6%), Odeda (2.3%), Ado-odo/Otta (2.3%), Ogun Waterside (3.8%) and Obafemi/Owode (4.2%). The mathematical mean of 'X' values in the study areas for Ogun State was 2.84. The calculated reinfection time (N months) for the LGAs are varied such as Ado-odo/Otta (12.7), Ogun Waterside (21.8), Obafemi/Owode (22.92), Odeda (25.45), and Ewekoro (25.9). The mean value for N in Ogun State was 21.75. The results obtained from MONRATE were compared with those obtained using the mathematical equation and found to be the same.

Malaria among pregnant women in Abeokuta, Nigeria.

Pregnant women were enrolled from two hospitals and a Traditional Birth Home (TBH) in Abeokuta, Nigeria and monitored monthly for malaria parasites from the first antenatal visit until delivery. A total of 466 pregnant women were recruited for the study. The prevalence of malaria was 57.4%, and was higher among women in the TBH. The prevalence of malaria in the first, second and third trimesters of pregnancy were 37.5%, 47.3% and 47.5% respectively. At the time of the first antenatal visit 35.6% of the women were already parasitaemic, with a high frequency observed among primigravids. The prevalence recorded in the ninth month of pregnancy (35.7%) was not statistically different from that recorded at first antenatal visit (P > 0.05). The need to improve the quality of care, malaria prevention and treatment given to pregnant women especially receiving antenatal care outside the hospital is recommended.

MONRATE; a descriptive tool for calculation and prediction of re-infection of Ascaris lumbricoides

The objective of the study was to develop an interactive and systematic descriptive tool; MONRATE for calculating and predicting reinfection rates and time of Ascaris lumbricoides following mass chemotherapy using levamisole. Each pupil previously treated was retreated 6 or 7 months after the initial treatment in Ogun State; Nigeria. The implementation was based on the theoretical equation for time-prevalence: Y = G [1 -(1-X)N-R]. Using the Psuedo- Code of the MONRATE tool; the calculated monthly reinfection rates (X) for the LGAs were 1.6in Ewekoro; 2.3in Odeda; 2.3in Ado-odo/Otta; 3.8in Ogun Waterside and 4.2in Obafemi/Owode. The mathematical mean of 'X' values in the study areas for Ogun State was 2.84. The calculated reinfection time (N months) for the LGAs varied such as Ado-odo/Otta (12.7); Ogun Waterside (21.8); Obafemi/Owode (22.92); Odeda (25.45); and Ewekoro (25.9). The mean value for N in Ogun State was 21.75. The results obtained from MONRATE were compared with those obtained using the mathematical equation and were found to be the same but MONRATE was faster in computation and more accurate. It is concluded that MONRATE is a veritable tool that can be used in the execution of control programme involving mass treatment against A. lumbricoides

Sampling mosquitoes with CDC light trap in rice field and plantation communities in Ogun State, Nigeria.

Mosquito species were sampled to determine the mosquito composition and abundance in rice field and plantation communities in Ogun State Nigeria. Mosquitoes were caught once weekly from four selected houses in each of the two communities by means of CDC light traps. A total of 47,501 mosquitoes representing fifteen species were caught in the two communities of which the rice field community accounted for 63.8% of the total catch. Mansonia africana constituted the most important biting mosquito in the two communities representing 62.1% and 39.1% in rice field and plantation communities, respectively. Other species in decreasing order of abundance were M. uniformis, Anopheles gambiae, Coquilletidia fuscopennata, An. moucheti, An. funestus, An. nili, Culex quinquefasciatus, Eretmapodites chrysogaster, Coq. metallica, Cx. annulioris, An. rhodesiensis, Aedes aegypti, An. squamosus and An. maculipennis. Seven mosquito species were caught throughout the year but mostly in the months of May to October. Abundance varied significantly between the study sites and between the months (F,1.11 =241.9 P<0.05) Most of the mosquitoes collected were unfed and nulliparous (87.1%). In spite of the high proportion of M. africana, its parous rate was low 0.53 and 0.59 in rice fileld and plantation, respectively. The highest parity was seen in Ae. aegypti (0.81-0.86) and An. gambiae, (0.69-0.68).

Anaemia in pregnancy: a survey of pregnant women in Abeokuta, Nigeria.

BACKGROUND: Anaemia in pregnancy is a common problem in most developing countries and a major cause of morbidity and mortality especially in malaria endemic areas. In pregnancy, anaemia has a significant impact on the health of the foetus as well as that of the mother. 20% of maternal deaths in Africa have been attributed to anaemia. OBJECTIVES AND METHODS: This study was therefore carried out to determine the prevalence of anaemia among pregnant women receiving antenatal care in two hospitals and a traditional birth home in order to obtain a broader prevalence data. Pregnant women were enrolled in the study at their first antenatal visit and were monitored through pregnancy for anaemia. Packed cell volume (PCV) was used to assess level of anaemia; Questionnaires were also administered to obtain demographic information. RESULTS: Three hundred and sixty five (76.5%) of the women were anaemic at one trimester of pregnancy or another. Anaemia were more prevalent among primigravidae (80.6%) than the multigravidae(74.5%)(P>0.05). Two hundred and eleven women (57.8%) had moderate anaemia while 147 (40.3%) had mild anaemia and 7(1.9%) were severely anaemic (5 (71.4%) of which were primigravidae). All severely anaemic women were under 30 years old. Women attending TBH for antenatal care were found to be more anaemic (81.2%) (Even at various trimesters of pregnancy) than those attending the hospitals (72.5%) (P<0.05). However, in all the antenatal centers more women were anaemic in the 2(nd) trimester of pregnancy. Forty-seven (9.8%) of the enrolled women booked for antenatal care in the first trimester, while 303(63.5%) booked in the second trimester and 127(26.6%) in the 3(rd) trimester of their pregnancies. 62.5% of these women were already anaemic at the time of antenatal booking, with a higher prevalence among the primigravidae (69.7%)(P < 0.05). Absence of symptoms of ill health was the major reason for late antenatal booking. Anaemia was higher among unemployed women and those with sickle cell traits. CONCLUSION: Educating women on early antenatal booking and including those in TBHs in health interventions is necessary to reduce the problem of anaemia in pregnancy in Nigeria.

Sampling mosquitoes with CDC light trap in rice field and plantation communities in Ogun State, Nigeria

Mosquito species were sampled to determine the mosquito composition and abundance in rice field and plantation communities in Ogun State Nigeria. Mosquitoes were caught once weekly from four selected houses in each of the two communities by means of CDC light traps. A total of 47,501 mosquitoes representing fifteen species were caught in the two communities of which the rice field community accounted for 63.8% of the total catch. Mansonia africana constituted the most important biting mosquito in the two communities representing 62.1% and 39.1% in rice field and plantation communities, respectively. Other species in decreasing order of abundance were M. uniformis, Anopheles gambiae, Coquilletidia fuscopennata, An. moucheti, An. funestus, An. nili, Culex quinquefasciatus, Eretmapodites chrysogaster, Coq.metallica, Cx annulioris, An. rhodesiensis, Aedes aegypti, An. squamosus and An. maculipennis. Seven mosquito species were caught throughout the year but mostly in the months of May to October. Abundance varied significantly between the study sites and between the months (F,1.11 =241.9 P<0.05) Most of the mosquitoes collected were unfed and nulliparous (87.1%). In spite of the high proportion of M. africana, its parous rate was low 0.53 and 0.59 in rice fileld and plantation, respectively. The highest parity was seen in Ae. aegypti (0.81-0.86) and An. gambiae, (0.69-0.68)

Urinary schistosomiasis in preschool children in settlements around Oyan Reservoir in Ogun State, Nigeria: implications for control.

We determined the prevalence of urinary schistosomiasis in preschool children below the age of 5 years in three settlements around Oyan Reservoir in Ogun State, Nigeria. Of 209 children screened, 150 (71.8%) had an infection, with no significant difference between males and females; 42.9% of infants were infected. Both prevalence and intensity of infection increased significantly with age (P < 0.005). Most (62.7%) infections were light (<50 eggs/10 ml urine). A 17.7 percentage of the children had visible haematuria, which increased with age (P < 0.005). Focus group discussions (FGDs) with adult men and women revealed that infection in preschool children was primarily because of exposure occasioned by the mothers' domestic (washing and bathing) and occupational (fishing) activities, while older children could go swimming on their own. Although the participants claimed that using a different water supply may not be effective in combating the disease, as their entire existence was tied to the reservoir, we propose that health education geared towards changing behaviour and attitudes is necessary. As preschool children are a source of both contamination and transmission, control programmes must take them into account.

Schistosoma haematobium infection in Abeokuta.

Ten years after the initial report of the outbreak of schistosomiasis in the vicinity of Sokori stream (a tributary of Ogun River) in Abeokuta, Nigeria, investigation was carried out to determine the present status of the disease, given the increased socioeconomic activities in the city. A total of 1670 school pupils in three schools within one kilometer radius of the stream, and 234 adults found using the stream for some water related activities were examined for eggs in their urine. One hundred and ninety-eight (11.9%) of the pupils and 98 (7.7%) of the adult group were infected. Compared to results of earlier surveys 1985 (55%) and 1987 (60.9%), there was a considerable reduction in the prevalence of infection. Also, 20.1% of pupils examined in the 1987 survey excreted between 200 and 1000 eggs/10 ml urine while the highest egg count in this survey was 189 eggs/10 ml urine. In addition to the improved water supply observed in the city, there has also been increased alternative recreational sites which may have reduced the propensity of the children to swim in the stream. Three snail species were seen (Bulinus forskalii, Physa waterlotti, and Melanoides voltae), none of which was naturally infected with cercariae.

Gastrointestinal helminth parasites of the black rat (Rattus rattus) in Abeokuta, southwest Nigeria.

A survey of 612 black rats, Rattus rattus (282 mates and 330 females), for infections with helminth parasites was carried out in Abeokuta, in southwest Nigeria. Three hundred and ninety six (64.7%) were infected with one or more of seven species of helminths comprising three cestodes (Hymenolepis diminuta, Taenia taeniaeformis (cyst) and Raillietina sp.) three nematodes (Mastophorus muris, Trichuris muris and Syphacia sp.) and one acanthocephalan (Moniliformis moniliformis). Although the prevalence of infection in males (76.6%) was more than in females (54.5%) (P<0.01), there was no difference in the mean intensity of infection, MI, (males=11.6+/-0.94, females=11.1+/-1.56). Among the different weight classes, rats of 100-130 g were more infected (893%) and had the highest mean intensity (MI=21.6) than those that weighed <100 g (47.1%, MI=6.4) and >130 g (73.9%, MI=9.3). Moniliformis moniliformis was the most common species encountered (39.2%) and had the highest mean intensity in both sexes (x=7.4+/-0.74). Considering the rat-man proximity, this finding has considerable public health implications.