Olaoluwa Pheabian Akinwale

Toxoplasma gondii infection: Relationship between seroprevalence and risk factors among primary schoolchildren in the capital areas of Democratic Republic of São Tomé and Príncipe, West Africa

BackgroundThe status of Toxoplasma gondii infection among primary schoolchildren (PSC) of the Democratic Republic of São Tomé and Príncipe (DRSTP), West Africa, remains unknown to date.MethodsA serologic survey and risk factors associated T. gondii infection among PSC in the DRSTP was assessed by the latex agglutination (LA) test and a questionnaire interview including parents’ occupation, various uncomfortable symptoms, histories of eating raw or undercooked food, drinking unboiled water, and raising pets, was conducted in October 2010. Schoolchildren from 4 primary schools located in the capital areas were selected, in total 255 serum samples were obtained by venipuncture, of which 123 serum samples were obtained from boys (9.8 ± 1.4 yrs) and 132 serum samples were obtained from girls (9.7 ± 1.3 yrs).ResultsThe overall seroprevalence of T. gondii infection was 63.1% (161/255). No significant gender difference in seroprevalence was found between boys (62.6%, 77/123) and girls (63.6%, 84/132) (p = 0.9). The older age group of 10 years had insignificantly higher seroprevalence (69.9%, 58/83) than that of the younger age group of 8 year olds (67.7%, 21/31) (p = 0.8). It was noteworthy that the majority of seropositive PSC (75.8%, 122/161) had high LA titers of ≥1: 1024, indirectly indicating acute or repeated Toxoplasma infection. Parents whose jobs were non-skilled workers (73.1%) showed significantly higher seroprevalence than that of semiskilled- (53.9%) or skilled workers (48.8%) (p < 0.05). Children who had a history of raising cats also showed significantly higher seroprevalence than those who did not (p < 0.001).Children who claimed to have had recent ocular manifestation or headache, i.e. within 1 month, seemed to have insignificantly higher seroprevalence than those who did not (p > 0.05).ConclusionsParents’ educational level and cats kept indoors seemed to be the high risk factors for PSC in acquisition of T. gondii infection. While, ocular manifestation and/or headache of PSC should be checked for the possibility of being T. gondii elicited. Measures such as improving environmental hygiene and intensive educational intervention to both PSC and their parents should be performed immediately so as to reduce T. gondii infection of DRSTP inhabitants including PSC and adults.

Seroprevalence, disease awareness, and risk factors for Toxocara canis infection among primary schoolchildren in Makoko, an urban slum community in Nigeria

In this study, we investigated the seroprevalence of Toxocara canis infection in southern Nigeria, which previously was unknown, in addition to evaluating disease awareness and potential risk factors for schoolchildren in an urban slum community. In total, 366 primary schoolchildren were investigated for the presence of anti-Toxocara IgG antibodies. Blood was collected and screened by a Western blot analysis based on the excretory-secretory antigens of larval T. canis (TcES), targeting low molecular weight bands of 24-35kDa specific for T. canis. Children were considered seropositive if their serum reacted with TcES when diluted to a titer of 1:32. Questionnaires concerning possible risk factors were given to the schoolchildren to acquire data on this infection. The overall seroprevalence of Toxocara infection was 86.1% (315/366). The logistic regression analysis of risk factors showed that childrens age (odds ratio (OR)=2.88, 95% confidence interval (CI)=1.08-7.66, p=0.03), contact with dogs (OR=0.51, 95% CI=0.28-0.94, p=0.03), the age of the dog (OR=0.34, 95% CI=0.18-0.68, p=0.002), the feeding location of the dog (OR=0.31, 95% CI=0.12-0.79, p=0.01), the consumption of raw vegetables (OR=0.89, 95% CI=0.54-1.48, p=0.004), and the drinking of unboiled water (OR=0.48, 95% CI=0.26-0.90, p=0.02) were risk factors associated with Toxocara infection. Although there was a high awareness of dogs being hosts of some parasites in this study, not much was known about T. canis. This is the first serological investigation of T. canis infection among primary schoolchildren in southern Nigeria. The high seroprevalence recorded is an indication of high transmission with the consequent risk of visceral or ocular larval migrans and neurologic toxocariasis in these children. Our findings suggest the need for prompt interventional measures, particularly health education on personal hygiene.

Biting behaviour of Simulium damnosum complex and Onchocerca volvulus infection along the Osun River, Southwest Nigeria

BackgroundStudies on biting behaviours and infectivity status of insect vectors are pre-requisites in understanding the epidemiology of the vector- borne diseases and planning effective control measures. A longitudinal study was carried out to investigate the transmission index of Simulium damnosum complex species along Osun River, South Western Nigeria. Adult flies were collected on human attractants from 07:00 to 18:00 hours for two consecutive days from February 2008 to June 2009 at three communities: Osun Eleja, Osun Ogbere and Osun Budepo. The infectivity rate was determined by dissection and Polymerase Chain Reaction amplification (PCR) of 0-150 genes of Onchocerca parasite using the pool screening technique.ResultsThe results indicated that the majority of the flies collected at the three sampling points were nulliparous as they accounted for 53.90%, 57.86% and 59.58% of the flies dissected at Osun Budepo, Osun Ogbere and Osun Eleja, respectively. The parous rate was higher during the dry season than the wet season but the difference was not statistically significant (p < 0.05). The biting activity of the parous flies showed two peaks at Osun Budepo and three peaks at Osun Eleja and Osun Ogbere. Of the 1,472 flies dissected and 1,235 flies screened by molecular method, none was infected with Onchocerca parasite at the three sampling points however the annual biting rates at the three communities were higher than 1,000 considered as tolerable value for a person living in an onchocerciasis zone by Word Health Organization.ConclusionThe study has provided the baseline data for further study on onchocerciasis transmission dynamics and the need to intercept man- simuliid vector contact at the study area.

Urinary schistosomiasis transmission in Epe, an urban community of Southwest Nigeria

Background: A survey of Schistosoma haematobium infection in Epe, an urban community in Lagos State, Southwest Nigeria, was carried out to ascertain the possibility that schistosomiasis, otherwise considered a rural disease, could reach urban populations. Materials and Methods: About 100 ml of voided urine samples from 200 pupils aged 6-13 years [109 (54.5%) males and 91 (45.5%) females], attending an Anglican primary school, Ebute Afuye, and a community primary school, Erepoto, were examined parasitologically for hematuria and S. haematobium ova following informed consent obtained from their parents/guardians. All samples were screened using polymerase chain reaction (PCR) amplification of the schistosome Dra1 gene. Fourteen Bulinus snails collected from the two sites, Ebute Afuye (6) and Erepoto (8), were screened for schistosome infection by the PCR amplification of the schistosome Dra1 gene. PCR-RFLP of the snails′ its region was analyzed for species identification and a subregion of the cox1 gene from four infected snails (two from each site) was amplified and sequenced. Results: In the Anglican primary school, Ebute Afuye, and community primary school, Erepoto, 16% and 29% were positive for hematuria, and 16% and 17% had schistosome ova, respectively. PCR analysis showed that 57% and 40% were positive for the infection in Anglican primary school, Ebute Afuye, and community primary school, Erepoto, respectively. PCR screening of the snails confirmed that four from Ebute Afuye and three from Erepoto were infected with schistosomes. PCR-RFLP showed that all the 14 snails were Bulinus truncatus while phylogenetic analysis of the sequenced partial cox1 gene corroborated the PCR-RFLP results. Conclusions: There was a high prevalence of S. haematobium infection among the participants detected by PCR, which was able to detect infection in cases otherwise shown to be negative by hematuria. We also observed that B. truncatus is one of the snail species responsible for the transmission of urinary schistosomiasis in the Epe community. For national control programs, it is very important that trends in the prevalence and intensity of schistosomiasis in urban cities be monitored.

Differentiating Schistosoma haematobium from Schistosoma magrebowiei and other closely related schistosomes by polymerase chain reaction amplification of a species specific mitochondrial gene

Introduction: Schistosoma haematobium infection afflicts about 150 million people in 53 countries in Africa and the Middle East. In many endemic areas, S. haematobium is sympatric with Schistosoma bovis, Schistosoma mattheei, Schistosoma curassoni, Schistosoma intercalatum and Schistosoma magrebowiei, its closely related species. In addition, they also develop in the same intermediate snail hosts. Since these schistosome species often infect snails inhabiting the same bodies of water, examining cercariae or infected snails for estimating transmission of S. haematobium is always confounded by the need to differentially identify S. haematobium from these other species. Recently, differentiating S. haematobium by polymerase chain reaction (PCR) from S. bovis, S. mattheei, S. curassoni and S. intercalatum, but not from S. magrebowiei was reported. However, to be able to evaluate residual S. haematobium transmission after control interventions in areas where S. haematobium may be sympatric with S. magrebowiei, a differential tool for accurate monitoring of infected snails is needed. Materials and Methods : Thus in this study, we developed a new PCR assay using a pair of primers, ShND-1/ShND-2, to amplify a target sequence of 1117 bp (GenBank accession number KF834975) from S. haematobium mitochondrion complete genome (GenBank accession number DQ157222). Sensitivity of the assay was determined by PCR amplification of different concentrations of S. haematobium gDNA serially diluted from 10ng to 0.1pg. For assay specificity, different concentrations of gDNA from S. haematobium and the other schistosome species, 20 positive urine samples and five controls as well as 20 infected snails were subjected to PCR amplification, while some of the PCR products were sequenced. Results : The assay detected up to 1pg of S. haematobium gDNA, while a differential identification of S. haematobium DNA content from other closely related species was achieved when applied to urine and naturally infected snails. When a protein-protein blast search was carried out using Blastp, the amplified sequence was found to encode a protein that shows a 100% similarity with S. haematobium nicotinamide adenine dinucleotide dehydrogenase subunit 3 (GenBank accession number YP_626524.1). Conclusion : The PCR assay was sensitive, specific and was able to successfully differentiate S. haematobium from S. magrebowiei, in addition to its other closely related animal infective schistosome species.

Seroepidemiological study and associated risk factors of Toxocara canis infection among preschool children in Osun State, Nigeria

Human toxocariasis is caused by the nematode, Toxocara canis and it is a poorly understood phenomenon in Nigeria. Seroepidemiological studies have not been previously carried out among the preschool aged children in Nigeria. A cross-sectional study was conducted in pre-school children in four communities from Osun State, Nigeria between January and July 2016. A total of 308 children Aged 9 months and 5 years were studied comprising 53.2% (164/308) male and 46.8% (144/308) female. Blood samples were collected and screened for the presence of anti-Toxocara IgG antibodies by Western blot analysis based on the excretory-secretory antigens of larva T. canis (TcES), targeting low molecular weight bands of 24 - 35kDa specific for T. canis. Questionnaires were given to parents/guardians of the studied children to collect information regarding relationship between infection and host factors. The overall seroprevalence of Toxocara infection was 37.3%. The seroprevalence in the studied preschool children ranged from 18.2% in children less than one year old to a max of 57.6% in children aged 3 years and above. The logistic regression analysis of risk factors showed that childrens age (odds ratio (OR)=6.12, 95% confidence interval (CI)=1.25-29.90, p=0.02), contact with dogs (OR=3.17, 95% CI=1.40-7.20, p=0.01) and parents religion (OR=0.54, 95% CI=0.32-0.91, p=0.02) were the risk factors associated with Toxocara infection. However, after adjustment by multivariate logistic regression analysis, contact with dogs (p=0.02) remained the only statistically significant risk factor. Preschool children were exposed early in life to T. canis infection as 18.18% of children less than one year old were infected. This is the first serological investigation of T. canis infection among preschool children in Nigeria. The results show high levels of exposure to T. canis infection among the studied group and contact with the dog plays the predominant risk factor. It indicates high transmission with the consequent of visceral or ocular larva migrans and neurologic disorder in these children. The results also provide baseline data for effective prevention strategies of toxocariasis in Southwest Nigeria and the study recommends prompt interventional measures, particularly health education on personal hygiene.

Current status of urinary schistosomiasis in communities around the Erinle and Eko-Ende Dams and the implications for schistosomiasis control in Nigeria

AbstractSchistosomiasis is an endemic disease in many parts of the world and the disease is associated with water resource development projects, such as dams, irrigation schemes, and rice and fish farming. The present study was designed to determine the prevalence and intensity of urinary schistosomiasis in five communities around the Erinle and Eko-Ende Dams in Osun State, Nigeria, using dipstickhaematuria, and parasitogical and molecular techniques. A total of 462 participants were screened, of whom 46.3%, 51.1% and 61.5% tested positive when using haematuria, microscopy and PCR respectively. The highest prevalence of the infection and intensity was in Illie (Erinle Dam), while Eko-Ajala (Eko-Ende Dam) had the least. Using analysis of variance and chi-square tests, the differences in the prevalence and intensity of the infection between the fve communities was statistically signifcant (p-value < 0.05). The prevalence and the intensity of the infection was higher in communities around Erinle Dam when com...

Molecular characterisation of the Simulium damnosum complex (Diptera: Simuliidae) found along the Osun River system, in south-western Nigeria.

Simulium damnosum s.l. are the only known vectors of Onchocerca volvulus in West Africa (Toè et al., 1997). At least nine sibling species of S. damnosum s.l. exist in this region and these siblings have varying vectorial capacities in the different ecozones (Wilson and Post, 1994). The savannadwelling group (S. damnosum s.s. and S. sirbanum) transmits the blinding, savanna strain of O. volvulus and the forest-dwelling group (S. squamosum and S. yahense) transmits the non-blinding, forest strain of the parasite (Tang et al., 1995). The members of the transition-zone-dwelling group (S. sanctipauli, S. leonense and S. soubrense) are commonly found in areas where the two strains of O. volvulus co-exist (Tang et al., 1995). Most of the classification of the S. damnosum s.l. in West Africa has been based on larval cytotaxonomy (Ibeh et al., 2006). The available cytotaxonomic techniques can only be applied to seventh-instar larvae and cannot be used to identify the adult flies that are involved in transmission. Adult S. damnosum s.l. have been investigated using iso-enzyme analysis (Thomson et al., 1990), morphotaxonomy (Garms and Zillman, 1984; Wilson et al., 1993), morphometrics (Garms et al., 1982; Wilson et al., 1993) and molecular techniques based on the amplification of the internal transcribed spacers (ITS) of the flies’ nuclear ribosomal DNA (Brockhouse et al., 1993). Unfortunately, each of these methods could only differentiate two or three of the sibling species, leaving the problem of adult identification unresolved. More recently, however, the amplification of the 16S ribosomal RNA and NADH dehydrogenase subunit 4 (ND4) mitochondrial genes has been found useful, and the electrophoretic migration of heteroduplex formations of these sequences has been used to distinguish at least six of the siblings that serve as the main vectors in the areas formerly covered by the Onchocerciasis Control Programme (OCP) in West Africa (Tang et al., 1995; Higazi et al., 2000). A heteroduplex assay has recently been employed to investigate the sibling composition of the biting adults of S. damnosum s.l. to be found along the Osun River, in south– western Nigeria. This river lies (at 8u209– 6u309N, 5u109–3u259E) in the forest zone of Nigeria, outside of the ‘OCP area’. Between February 2008 and January 2009, adult S. damnosum s.l. were collected every fortnight, as they landed on human volunteers at three catching points along the river (at Eleja, Ogbere and Budepo), and then morphologically classified into forest or savanna flies (Kurtak et al., 1981; Wilson et al., 1993). Fifty flies were randomly selected from the collections made during each of the three seasonal peaks (April–June, July–September and October–March; Mayr, 1969). The DNA in each selected fly was extracted using a commercial kit (DNeasyH blood and tissue kit; QIAGEN, Hilden, Germany) and then run in a PCR designed to amplify ND4 sequences (Tang et al., 1995). The denaturation and renaturation of the heteroduplex of the PCR products was carried out using S. damnosum s.s. as the heteroduplex driver. The heteroduplex Annals of Tropical Medicine & Parasitology, Vol. 104, No. 8, 679–683 (2010)

Toxoplasma gondii: seroprevalence and associated risk factors among preschool-aged children in Osun State, Nigeria

Background Toxoplasma gondii is an ubiquitous apicomplexan parasite, which causes toxoplasmosis in animals and humans worldwide. However, little is known about T. gondii infection among preschool-aged children in Nigeria. Methods A cross-sectional study of 272 preschool children aged 2.25±1.09 years from four communities (Edunabon, Erin-Ijesha, Ijebu-jesa and Ile-Ife) in Osun State, Nigeria was conducted between January and July 2016, and the demographic data was obtained via questionnaires. Antibody titres against T. gondii of serum samples were assessed by ELISA. Results The overall seroprevalence of T. gondii infection was 6.9% (19/272). There was no significant difference in seroprevalence of T. gondii infection between boys (7.04%; 10/142) and girls (6.92%; 9/130; p=0.97). No associations were found between age, gender, parental educational level, occupation and religion, and T. gondii seropositivity. None showed statistical significance between the risk factors tested after multivariate adjustment; nevertheless, residing in Ijebu-jesa community was shown to be associated with an increased risk of infection (p=0.04). Conclusion This is the first report of T. gondii infection among preschool children in Nigeria. Prevalence studies such as this could help in the development of strategies for the future for disease prevention and control of T. gondii transmission.