Whipworm and roundworm infections.

Trichuriasis and ascariasis are neglected tropical diseases caused by the gastrointestinal dwelling nematodes Trichuris trichiura (a whipworm) and Ascaris lumbricoides (a roundworm), respectively. Both parasites are staggeringly prevalent, particularly in tropical and subtropical areas, and are associated with substantial morbidity. Infection is initiated by ingestion of infective eggs, which hatch in the intestine. Thereafter, T. trichiura larvae moult within intestinal epithelial cells, with adult worms embedded in a partially intracellular niche in the large intestine, whereas A. lumbricoides larvae penetrate the gut mucosa and migrate through the liver and lungs before returning to the lumen of the small intestine, where adult worms dwell. Both species elicit type 2 anti-parasite immunity. Diagnosis is typically based on clinical presentation (gastrointestinal symptoms and inflammation) and the detection of eggs or parasite DNA in the faeces. Prevention and treatment strategies rely on periodic mass drug administration (generally with albendazole or mebendazole) to at-risk populations and improvements in water, sanitation and hygiene. The effectiveness of drug treatment is very high for A. lumbricoides infections, whereas cure rates for T. trichiura infections are low. Novel anthelminthic drugs are needed, together with vaccine development and tools for diagnosis and assessment of parasite control in the field.

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.

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 children's 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 parent's 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.

Ascaris co-infection does not alter malaria-induced anaemia in a cohort of Nigerian preschool children.

BACKGROUND: Co-infection with malaria and intestinal parasites such as Ascaris lumbricoides is common. Malaria parasites induce a pro-inflammatory immune response that contributes to the pathogenic sequelae, such as malarial anaemia, that occur in malaria infection. Ascaris is known to create an anti-inflammatory immune environment which could, in theory, counteract the anti-malarial inflammatory immune response, minimizing the severity of malarial anaemia. This study examined whether Ascaris co-infection can minimize the severity of malarial anaemia. METHODS: Data from a randomized controlled trial on the effect of antihelminthic treatment in Nigerian preschool-aged (6-59 months) children conducted in 2006-2007 were analysed to examine the effect of malaria and Ascaris co-infection on anaemia severity. Children were enrolled and tested for malaria, helminths and anaemia at baseline, four, and eight months. Six hundred and ninety subjects were analysed in this study. Generalized linear mixed models were used to assess the relationship between infection status and Ascaris and Plasmodium parasite intensity on severity of anaemia, defined as a haemoglobin less than 11 g/dL. RESULTS: Malaria prevalence ranged from 35-78% over the course of this study. Of the malaria-infected children, 55% were co-infected with Ascaris at baseline, 60% were co-infected four months later and 48% were co-infected eight months later, underlining the persistent prevalence of malaria-nematode co-infections in this population. Over the course of the study the percentage of anaemic subjects in the population ranged between 84% at baseline and 77% at the eight-month time point. The odds of being anaemic were four to five times higher in children infected with malaria compared to those without malaria. Ascaris infection alone did not increase the odds of being anaemic, indicating that malaria was the main cause of anaemia in this population. There was no significant difference in the severity of anaemia between children singly infected with malaria and co-infected with malaria and Ascaris. CONCLUSION: In this cohort of Nigerian preschool children, malaria infection was the major contributor to anaemia status. Ascaris co-infection neither exacerbated nor ameliorated the severity of malarial anaemia.

Plasma cytokines, chemokines and cellular immune responses in pre-school Nigerian children infected with Plasmodium falciparum.

BACKGROUND: Malaria is a major cause of morbidity and mortality worldwide with over one million deaths annually, particularly in children under five years. This study was the first to examine plasma cytokines, chemokines and cellular immune responses in pre-school Nigerian children infected with Plasmodium falciparum from four semi-urban villages near Ile-Ife, Osun State, Nigeria. METHODS: Blood was obtained from 231 children (aged 39-73 months) who were classified according to mean P. falciparum density per µl of blood (uninfected (n = 89), low density (<1,000, n = 51), medium density (1,000-10,000, n = 65) and high density (>10,000, n = 22)). IL-12p70, IL-10, Nitric oxide, IFN-γ, TNF, IL-17, IL-4 and TGF-ß, C-C chemokine RANTES, MMP-8 and TIMP-1 were measured in plasma. Peripheral blood mononuclear cells were obtained and examined markers of innate immune cells (CD14, CD36, CD56, CD54, CD11c AND HLA-DR). T-cell sub-populations (CD4, CD3 and γδTCR) were intracellularly stained for IL-10, IFN-γ and TNF following polyclonal stimulation or stimulated with malaria parasites. Ascaris lumbricoides was endemic in these villages and all data were analysed taking into account the potential impact of bystander helminth infection. All data were analysed using SPSS 15 for windows and in all tests, p <0.05 was deemed significant. RESULTS: The level of P. falciparum parasitaemia was positively associated with plasma IL-10 and negatively associated with IL-12p70. The percentage of monocytes was significantly decreased in malaria-infected individuals while malaria parasitaemia was positively associated with increasing percentages of CD54+, CD11c+ and CD56+ cell populations. No association was observed in cytokine expression in mitogen-activated T-cell populations between groups and no malaria specific immune responses were detected. Although A. lumbricoides is endemic in these villages, an analysis of the data showed no impact of this helminth infection on P. falciparum parasitaemia or on immune responses associated with P. falciparum infection. CONCLUSIONS: These findings indicate that Nigerian children infected with P. falciparum exhibit immune responses associated with active malaria infection and these responses were positively associated with increased P. falciparum parasitaemia.

Impact of repeated four-monthly anthelmintic treatment on Plasmodium infection in preschool children: a double-blind placebo-controlled randomized trial.

BACKGROUND: Helminth infections can alter susceptibility to malaria. Studies need to determine whether or not deworming programs can impact on Plasmodium infections in preschool children. METHODS: A double-blind placebo-controlled randomised trial was conducted to investigate the impact of anthelmintic treatment on Plasmodium infection in children aged 12-59 months. Children were randomly assigned to receive either albendazole or placebo every four months for 12 months with a follow-up at 14 months. RESULTS: 320 Children (out of 1228, 26.1%) complied with all the follow-up assessments. Plasmodium prevalence and mean Plasmodium parasite density was significantly higher in the treatment group (44.9% and 2319 ± SE 511) compared to the placebo group (33.3% and 1471 ± 341) at baseline. The odds of having Plasmodium infection increased over time for children in both the placebo and treatment groups, however this increase was significantly slower for children in the treatment group (P = 0.002). By month 14, mean Plasmodium density had increased by 156% in the placebo group and 98% in the treatment group but the rate of change in Plasmodium density was not significantly different between the groups. The change from baseline in haemoglobin had a steeper increase among children in the treatment group when compared to the placebo group but this was not statistically significant. CONCLUSIONS: Repeated four-monthly anthelminthic treatments for 14 months resulted in a significantly lower increase in the prevalence of Plasmodium infection in preschool children which coincided with a reduction in both the prevalence and intensity of A. lumbricoides infections. TRIAL REGISTRATION: Current controlled trials ISRCTN44215995.

Identification of a high diversity of Cryptosporidium species genotypes and subtypes in a pediatric population in Nigeria.

A longitudinal study was conducted to determine the epidemiology of Cryptosporidium in 1,636 children in Nigeria. Oocyst prevalence ranged from 15.6% to 19.6% over one year. Cryptosporidium hominis (34), C. parvum (25), C. parvum/C. hominis (4), C. meleagridis (5), Cryptosporidium rabbit genotype (5), Cryptosporidium cervine genotype (3), and C. canis (1) were identified by polymerase chain reaction-restriction fragment length polymorphism analysis. Glycoprotein 60 subgenotyping showed that 28 amplifiable C. hominis isolates consisted of 12 subtypes that belonged to 5 subtype families (Ia, Ib, Id, Ie, and 1 novel subtype family, Ih) and 23 amplifiable C. parvum isolates consisted of 6 subtypes that belonged to 4 subtype families (IIa, IIc, Iii, and IIm). Three C. meleagridis isolates sub-genotyped by sequence analysis of the small subunit ribosomal RNA gene fragment were type 1. This study is the first one to genetically characterize Cryptosporidium species and subtypes in Nigeria and highlights the presence of a high Cryptosporidium diversity in this pediatric population.

Patterns of soil-transmitted helminth infection and impact of four-monthly albendazole treatments in preschool children from semi-urban communities in Nigeria: a double-blind placebo-controlled randomised trial.

BACKGROUND: Children aged between one and five years are particularly vulnerable to disease caused by soil-transmitted helminths (STH). Periodic deworming has been shown to improve growth, micronutrient status (iron and vitamin A), and motor and language development in preschool children and justifies the inclusion of this age group in deworming programmes. Our objectives were to describe the prevalence and intensity of STH infection and to investigate the effectiveness of repeated four-monthly albendazole treatments on STH infection in children aged one to four years. METHODS: The study was carried out in four semi-urban villages situated near Ile-Ife, Osun State, Nigeria. The study was a double-blind placebo-controlled randomised trial. Children aged one to four years were randomly assigned to receive either albendazole or placebo every four months for 12 months with a follow-up at 14 months. RESULTS: The results presented here revealed that 50% of the preschool children in these semi-urban communities were infected by one or more helminths, the most prevalent STH being Ascaris lumbricoides (47.6%). Our study demonstrated that repeated four-monthly anthelminthic treatments with albendazole were successful in reducing prevalence and intensity of A. lumbricoides infections. At the end of the follow-up period, 12% and 43% of the children were infected with A. lumbricoides and mean epg was 117 (S.E. 50) and 1740 (S.E. 291) in the treatment and placebo groups respectively compared to 45% and 45% of the children being infected with Ascaris and mean epg being 1095 (S.E. 237) and 1126 (S.E. 182) in the treatment and placebo group respectively at baseline. CONCLUSION: Results from this study show that the moderate prevalence and low intensity of STH infection in these preschool children necessitates systematic treatment of the children in child health programmes.