Anaemia in Ugandan preschool-aged children: the relative contribution of intestinal parasites and malaria

Prognostics of multiple malaria episodes and nutritional status in children aged 6 to 59 months from 2013 to 2017 in Dangassa, Koulikoro region, Mali

BACKGROUND

In Africa, the relationship between childhood nutritional status and malaria remains complex and difficult to interpret. Understanding it is important in the improvement of malaria control strategies. This study aimed to assess the influence of nutritional status on the occurrence of multiple malaria episodes in children aged 6 to 59 months between 2013 and 2017 living in the village of Dangassa, Mali.

METHODS

A community-based longitudinal study was conducted using cross-sectional surveys (CSSs) at the beginning (June) and end (November) of the malaria transmission season associated with passive case detection (PCD) at the Dangassa Community Health Centre. Children with asymptomatic malaria infection during cross-sectional surveys were selected and their malaria episodes followed by PCD. Malaria indicators in person-months were estimated using an ordinal-logistic model repeated on subjects during follow-up periods.

RESULTS

The incidence rate (IR) during the period of high transmission (June to October), for 1 episode and for 2 + episodes peaked in 2013 with 65 children (IR = 95.73 per 1000 person-months) and 24 cases (IR = 35.35 per 1000 person-months), respectively. As expected, the risk of multiple episodes occurring during the period of high transmission was 3.23 compared to the period of low transmission after adjusting for other model parameters (95% CI [2.45-4.26], p = 0.000). Children with anaemia were at high risk of having multiple episodes (OR = 1.6, 95% CI [1.12-2.30], p = 0.011). However, the risk of having 2 + episodes for anemic children was higher during the period of low transmission (RR = 1.67, 95% CI [1.15-2.42], p = 0.007) compared to the period of high transmission (RR = 1.58, 95% CI [1.09-2.29], p = 0.016). The trend indicated that anemic and underweight children were significantly associated with multiple malaria episodes during the period of low transmission (p < 0.001).

CONCLUSION

Results show that multiple episodes of malaria are significantly related to the nutritional status (anaemia and underweight) of the child during the two transmission seasons and more pronounced during the dry season (period of low transmission). Further research including other malnutrition parameters will be needed to confirm these findings.

Pathogenicity and virulence of malaria: Sticky problems and tricky solutions

Infections with Plasmodium falciparum and Plasmodium vivax cause over 600,000 deaths each year, concentrated in Africa and in young children, but much of the world's population remain at risk of infection. In this article, we review the latest developments in the immunogenicity and pathogenesis of malaria, with a particular focus on P. falciparum, the leading malaria killer. Pathogenic factors include parasite-derived toxins and variant surface antigens on infected erythrocytes that mediate sequestration in the deep vasculature. Host response to parasite toxins and to variant antigens is an important determinant of disease severity. Understanding how parasites sequester, and how antibody to variant antigens could prevent sequestration, may lead to new approaches to treat and prevent disease. Difficulties in malaria diagnosis, drug resistance, and specific challenges of treating P. vivax pose challenges to malaria elimination, but vaccines and other preventive strategies may offer improved disease control.

Prognostics of multiple malaria episodes and nutritional status in children aged 6 to 59 months from 2013 to 2017 in Dangassa, Mali

Background In Africa, the relationship between nutritional status and malaria remains complex and difficult to interpret in children. Understanding it is important in the development of malaria control strategies. This study evaluated the effect of nutritional status on the occurrence of multiple malaria episodes in children aged 6 to 59 months between 2013 and 2017 living in the village of Dangassa, Mali. Methods A community-based longitudinal study was conducted using cross-sectional surveys (SSCs) at the beginning (June) and end (November) of the malaria transmission season associated with passive case detection (PCD) at the Dangassa Community Health Center. Children with asymptomatic malaria infection during cross-sectional surveys were selected and their malaria episodes followed by PCD. Palustrine indicators in person-months were estimated using an ordinal-logistic model repeated on subjects during follow-up periods. Results The incidence rate (IR) during the period of high transmission (June to October), for 1 episode and for 2 + episodes peaked in 2013 with 65 children (IR = 95.73 per 1000 person-months) and 24 cases (IR = 35.35 per 1000 person-months), respectively. As expected, the risk of multiple episodes occurring during the period of high transmission was 3.23 compared to the period of low transmission after adjusting for other model parameters (95% CI = [2.45-4.26], p = 0.000). Children with anemia were at high risk of having multiple episodes (OR = 1.6, 95% CI [1.12-2.30], p = 0.011). However, the risk of having 2 + episodes for anemic children was higher during the period of low transmission (RR = 1.67, 95% CI [1.15-2.42], p = 0.007) compared to the period of high transmission (RR = 1.58, 95% CI [1.09-2.29], p = 0.016). The trend indicated that anemic and underweight children were significantly associated with multiple malaria episodes during the period of low transmission (p < = 0.001). Conclusion Our results indicate that multiple episodes of malaria are significantly related to the nutritional status (anemia and underweight) of the child during the two transmission seasons and more pronounced during the dry season (period of low transmission). Further research including other malnutrition parameters will be needed to confirm our findings.

Epidemiology of pediatric schistosomiasis in hard-to-reach areas and populations: a scoping review

BACKGROUND

Schistosomiasis affects over 250 million people worldwide. Despite children and the poor being key risk groups, limited research and control activities target pre-school aged children (PSAC) and hard-to-reach populations. As endemic countries shift the goals of their schistosomiasis programs from morbidity control to disease elimination, there is a need for inclusive planning to cover all affected age groups from all geographical areas and populations to achieve sustainable impact and health equity.

METHODS

We conducted searches in MEDLINE, Web of Science, Embase (Ovid), and LILACS per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Extension for Scoping Reviews (PRISMA-ScR) guidelines. Quality assessment of identified articles was done using the Joanna Briggs Institute Prevalence Critical Appraisal Tool. Relevant study data were extracted from the articles and entered into Microsoft Excel 2016 for descriptive analysis.

RESULTS

From the 17,179 screened articles, we identified 13 eligible studies on schistosomiasis in PSAC living in hard-to-reach areas and populations. All identified studies were from sub-Saharan Africa. The mean sample size of the retained studies was 572, with a balanced sex distribution among the young children sampled in each study. Ten studies investigated Schistosoma mansoni, one investigated Schistosoma haematobium, while two covered both S. mansoni and S. haematobium in the target population. The prevalence of S. mansoni among PSAC in the included studies was estimated at 12.9% in Ghana, 80.3-90.5% in Kenya, 35.0% in Madagascar, 9.6-78.0% in Senegal, 11.2-35.4% in Sierra Leone, 44.4-54.9% in Tanzania and 39.3-74.9% in Uganda. Out of the three studies that investigated S. haematobium, the presence of the infection was reported in only one study carried out in Nigeria. Schistosome infections reported in nearly all studies included in this review were of light intensity. Only one study conducted in Nigeria documented visible hematuria in 17.7% of the PSAC studied.

CONCLUSIONS

The findings document the high prevalence of schistosomiasis among PSAC in hard-to-reach populations and underscore the need to consider this population subgroup when designing the expansion of preventive chemotherapy and schistosomiasis control activities.

Impact of a 5-Year Mass Drug Administration Programme for Soil-Transmitted Helminthiases on the Spatial Distribution of Childhood Anaemia in Burundi from 2007 to 2011

Background: Childhood anaemia affects 1.8 billion people globally. Little is known about the long-term impact of mass drug administration (MDA) for the control of soil-transmitted helminthiases (STH) on the spatiotemporal variation of anaemia prevalence and severity. We describe the long-term spatiotemporal impact of a 5-year STH MDA programme (2007−2011) on the prevalence of anaemia and anaemia severity in school-aged children (SAC) in Burundi. Methodology/Principal Findings: We used annual haemoglobin concentration and STH data collected during 2007−2011 in 31 schools in Burundi. Spatial dependence in prevalence and severity of anaemia was assessed using semivariograms. Bayesian geostatistical models were developed to (a) quantify the role of STH (adjusted for other anaemia determinants) in the spatiotemporal distribution of anaemia prevalence/severity, and (b) predict the geographical variation of both outcomes across Burundi. Adjusted population data were used to estimate the geographical distribution of the number of SAC at risk of anaemia and with low and moderate/severe anaemia. Infections with Ascaris lumbricoides and Trichuris trichiura were positively and significantly associated with childhood anaemia; hookworm infections were not. A significant decrease in anaemia prevalence, from 40−50% (2008) to 10−20% (2011) was predicted in western areas. The predicted prevalence of low-severity anaemia decreased from 40−50% (2008) to <20% (2011) in southern and eastern areas. Moderate/high-severity anaemia was concentrated in western regions of Burundi, with pockets of moderate/high-severity anaemia in central and northern regions in 2008. The overall number of predicted anaemic children decreased from 443,657 (2008) to 232,304 (2011), with a resurgence after MDA disruption in 2010 (to 480,605). Prevalence of low- and moderate-severity anaemia was higher in boys than in girls. Conclusions/Significance: Despite ongoing MDA, the prevalence of anaemia in SAC remained high and increased in certain parts of the country. It is recommended that MDA programmes targeting STH are complemented with specific anaemia interventions.

Implication of asymptomatic and clinical Plasmodium falciparum infections on biomarkers of iron status among school-aged children in Malawi

Background

Iron status is considered as a continuum from an iron deficiency with anaemia, without anaemia, varying amounts of stored iron to iron overload. The burden of Plasmodium falciparum infections is typically high among school-aged children (SAC). Nonetheless, SAC are often less likely to be covered by malaria interventions, making them a group with an untreated reservoir of parasite transmission. This study aimed to assess the effects of asymptomatic and clinical malaria infections on biochemical markers of iron status among SAC in Malawi.

Methods

Data from the 2015–2016 Malawi Micronutrient Survey (MNS) was used and multivariable logistic regression models using a generalized estimating equation to account for the complex cluster survey design were constructed. Blood samples of 684 children aged 5 to 14 years old were evaluated for clinical and asymptomatic malaria infections. Furthermore, blood samples were used to estimate haemoglobin (Hb), serum ferritin (SF) and, soluble transferrin receptors (sTfR) concentrations.

Results

Of the 684 SAC analysed, approximately 42% had asymptomatic malaria, while 41.0% had clinical malaria. Anaemia (low Hb levels), iron deficiency (low SF concentration), and functional iron deficiency (high sTfR levels) were found in 20%, 5%, and 30% of the children, respectively. School-aged children with asymptomatic malaria had increased odds of being anaemic (adjusted odds ratio [aOR]: 3.71, 95% confidence interval [CI]: 2.29–5.99) and increased levels of sTfR (aOR: 3.00, 95% CI 2.01–4.47). Similarly, SAC with clinical malaria had increased odds of being anaemic (aOR: 3.54, 95% CI 2.19–5.72) and increased levels of sTfR (aOR: 3.02, 95% CI 2.02–4.52).

Conclusions

Both asymptomatic and clinical malaria were independent risk factors for anaemia and functional iron deficiency (FID). The notion that asymptomatic and clinical malaria were associated with both anaemia and FID underscores the need for public health programmers to consider adding mass screening and treatment for malaria to existing school-based health programmes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04297-1.

Regression of Schistosoma mansoni associated morbidity among Ugandan preschool children following praziquantel treatment: A randomised trial

Preschool children suffer from morbidity attributable to Schistosoma mansoni. We compared a single and double dose of praziquantel treatment on the regression of S. mansoni associated morbidity in children less than six years in Uganda. We measured the sizes of spleen and liver as well as liver fibrosis before treatment and 8 months after treatment among children who either received one dose (n = 201) or two doses (n = 184) of praziquantel (standard oral dose of 40 mg/kg body weight). Heamoglobin measurements were also taken. Overall, liver enlargement reduced from 52.2% (95% CI (Confidence interval) 45.1, 59.3) to 17.9% (95% CI 12.9, 23.9) with a single dose and from 48.4 (95% CI 40.9, 55.8) to 17.9% (95% CI 12.7, 24.3) with a double dose and there was no significant difference between the changes in proportion of children with enlarged liver between the two treatment groups. The proportion of children with enlarged spleen was not significantly reduced in the group treated with either one or two doses, 47.8% (95% CI 41.7, 54.9) to 45.3% (95% CI 38.3, 52.4) and 48.4% (95% CI 40.9,55.8) to 40.8% 95% CI 33.6, 48.2), respectively. Liver fibrosis detected among children getting single dose (n = 9) or double doses (n = 13) resolved after treatment with praziquantel. The number of children with low heamoglobin significantly reduced from 51.2% (95% CI 44.1, 58.3) to 0.5% (0.2, 0.8) and 61.4% (95% CI 53.9,68.5) to 1.1% (95% CI 0.1, 3.9) after single and double dose treatment, respectively. These results suggest that there is no evidence of a difference in effect between one dose of praziquantel and two doses in reversing morbidity attributable to S. mansoni among children less than six years of age.

Molecular Epidemiology of Mansonella Species in Gabon

Mansonella perstans, a filarial nematode, infects large populations in Africa and Latin America. Recently, a potential new species, Mansonella sp "DEUX," was reported. Carriage of endosymbiotic Wolbachia opens treatment options for Mansonella infections. Within a cross-sectional study, we assessed the prevalence of filarial infections in 834 Gabonese individuals and the presence of the endosymbiont Wolbachia. Almost half of the participants (400/834 [48%]) were infected with filarial nematodes, with Mansonella sp "DEUX" being the most frequent (295/400 [74%]), followed by Loa loa (273/400 [68%]) and Mansonella perstans (82/400 [21%]). Being adult/elderly, male, and living in rural areas was associated with a higher risk of infection. Wolbachia carriage was confirmed in M. perstans and Mansonella sp "DEUX." In silico analysis revealed that Mansonella sp "DEUX" is not detected with currently published M. perstans-specific assays. Mansonella infections are highly prevalent in Gabon and might have been underreported, likely also beyond Gabon.

Malaria and helminth co-infections in children living in endemic countries: A systematic review with meta-analysis

Background

Current knowledge on the burden of, and interactions between malaria and helminth co-infections, as well as the impact of the dual infections on anaemia, remains inconclusive. We have conducted a systematic review with meta-analysis to update current knowledge as a first step towards developing and deploying coordinated approaches to the control and, ultimately, elimination of malaria-helminth co-infections among children living in endemic countries.

Methodology/Principal findings

We searched Medline, Embase, Global Health and Web of Science from each database inception until 16 March 2020, for peer-reviewed articles reporting malaria-helminth co-infections in children living in endemic countries. No language restriction was applied. Following removal of duplicates, two reviewers independently screened the studies for eligibility. We used the summary odds ratio (OR) and 95% confidence intervals (CI) as a measure of association (random-effects model). We also performed Chi-square heterogeneity test based on Cochrane’s Q and evaluated the severity of heterogeneity using I² statistics. The included studies were examined for publication bias using a funnel plot and statistical significance was assessed using Egger’s test (bias if p<0.1).

Fifty-five of the 3,507 citations screened were eligible, 28 of which had sufficient data for meta-analysis. The 28 studies enrolled 22, 114 children in 13 countries across sub-Saharan Africa, Southeast Asia and South America. Overall, the pooled estimates showed a prevalence of Plasmodium-helminth co-infections of 17.7% (95% CI 12.7–23.2%). Summary estimates from 14 studies showed a lower odds of P. falciparum infection in children co-infected with Schistosoma spp (OR: 0.65; 95%CI: 0.37–1.16). Similar lower odds of P. falciparum infection were observed from the summary estimates of 24 studies in children co-infected with soil transmitted helminths (STH) (OR: 0.42; 95%CI: 0.28–0.64).

When adjusted for age, gender, socio-economic status, nutritional status and geographic location of the children, the risk of P. falciparum infection in children co-infected with STH was higher compared with children who did not have STH infection (OR = 1.3; 95% CI 1.03–1.65).

A subset of 16 studies showed that the odds of anaemia were higher in children co-infected with Plasmodium and STH than in children with Plasmodium infection alone (OR = 1.20; 95% CI: 0.59–2.45), and were almost equal in children co-infected with Plasmodium-Schistosoma spp or Plasmodium infection alone (OR = 0.97, 95% CI: 0.30–3.14).

Conclusions/Significance

The current review suggests that prevalence of malaria-helminth co-infection is high in children living in endemic countries. The nature of the interactions between malaria and helminth infection and the impact of the co-infection on anaemia remain inconclusive and may be modulated by the immune responses of the affected children.

Updated evidence is needed to guide the planning and implementation of appropriate interventions for control of mixed infections involving malaria and worms affecting children living in endemic countries. We performed a systematic review and meta-analysis to update current knowledge on the magnitude of the burden of dual infections with malaria and worms in children in the developing world. We searched all published articles available in Medline, Embase, Global Health and Web of Science from the database inception until 16 March 2020, without any language restriction. We found 55 eligible studies, and 28 of these studies were included in the meta-analysis. A summary of the evidence synthesis showed that the burden of dual infections involving malaria and worm parasites is high in children and varies significantly across endemic countries. There was a lower risk of P. falciparum infection in children infected with soil transmitted helminths (STH) or S. haematobium or S.mansoni. Conversely, the odds of anaemia were higher in children who had dual infections with Plasmodium and STH parasites than in children with a Plasmodium infection alone while the odds of anaemia were almost equal in children who were co-infected with Plasmodium-Schistosoma compared to those with a Plasmodium infection alone. These findings underscore the need to further understand the epidemiology of malaria-helminth co-infections in order to support implementation of appropriate interventions for control and, ultimately, elimination of the dual infections in children living in endemic countries, especially low and middle-income countries (LMIC).

Relationship between blood Lead status and anemia in Ugandan children with malaria infection

BACKGROUND

In Uganda, childhood anemia remains a health challenge and is associated with malaria infection as well as iron deficiency. Iron deficiency is intertwined with nutritional status, age and other comorbidities including helminths and Lead toxicity. Environmental Lead levels accounts for one's blood Lead (BL) levels. Blood Lead competitively blocks iron absorption, inhibits hemoglobin (Hb) biosynthesis and elevates free erythrocyte protoporphyrin (FEP) levels. Lead toxicity's contribution towards anemia pathogenesis, especially during malaria infection has not been studied. Concomitant exposure to both malaria infection and Lead pollution, exacerbates the anemia status. This study therefore aimed at expounding the anemia status of these Ugandan children aged under 5years who are exposed to both malaria infection and environmental Lead pollution.

METHODS

Briefly, venous blood samples from 198 children were microscopically assayed for malaria parasite density (PD), and hemoglobin (Hb) concentrations using the cyanmethemoglobin method, while BL and FEP levels were determined by the standard atomic absorption spectrophotometric and fluorometric methods respectively.

RESULTS

One hundred and fifty-one (76.3%) of the children analyzed had moderate anemia (Hb <10>5 g/dL) with Means of BLL=8.6 µg/dL, Hb =7.5 g/dL, FEP/Hb =8.3 µg/g and PD =3.21×10³ parasites / µL, while eight (4%) were severely anemic (<5 g/dL). Regression analysis and statistical correlation between PD and Hb (r = -0.231, R²= 0.15 P-value < 0.001) was negative and weak as compared to that between FEP/Hb and Hb (r = -0.6, R²=0.572 P-value=0.001).

CONCLUSION

Based on the study's findings, we conclude that BL significantly contributes to the pathogenesis of anemia and therefore its co-existence with malaria infection in the host exacerbates the anemia status.

Intermittent preventive treatment of malaria delivered to primary schoolchildren provided effective individual protection in Jinja, Uganda: secondary outcomes of a cluster-randomized trial (START-IPT)

BACKGROUND

Intermittent preventive treatment (IPT) of malaria is recommended as policy for certain high-risk populations, but not currently for schoolchildren. A cluster-randomized trial was conducted to evaluate the effect of IPT with dihydroartemisinin-piperaquine (DP) on primary schoolchildren in Jinja, Uganda. Results of the impact of IPT of schoolchildren on community-level transmission have been reported previously. Here, secondary outcomes from a school-based survey are presented.

METHODS

Eighty-four clusters (one primary school plus 100 households) were randomized to intervention and control (1:1 ratio). Participants from intervention schools received monthly IPT with DP for up to 6 rounds (June-December 2014). At endline (November-December 2014), randomly selected children from all 84 schools were surveyed (13 per school) and thick blood smears were done. Those with fever or history of fever were tested with rapid diagnostic tests (RDTs) for malaria. Haemoglobin was measured in every fifth participant. Outcome measures included prevalence of asexual parasites and gametocytes (by microscopy), and prevalence of anaemia. Prevalence outcomes were analysed using generalized linear Poisson models with log link function, incorporating a cluster-level random intercept and quantified using prevalence risk ratios.

RESULTS

Among 23,280 students listed on the 42 intervention school registers, 10,079 (43.3%) aged 5-20 years were enrolled into the IPT intervention and received at least one dose of DP; of these, 9286 (92.1%) received at least one full (3-day) course. In total, 1092 children were enrolled into the final school survey (546 per arm) and had a thick blood smear done; of these, 255 had haemoglobin measured (129 intervention, 126 control). Children in the intervention arm were less likely to have asexual parasites (9.2% intervention vs 44.1% control, adjusted risk ratio [aRR] 0.22 [95% CI 0.16-0.30] p < 0.001), gametocytes (3.1% intervention vs 9.5% control, aRR 0.34 [95% CI 0.20-0.56] p < 0.001), fever (20.2% intervention vs 56.2% control, aRR 0.35 [95% CI 0.25-0.50] p < 0.001), or symptomatic malaria (5.1% intervention vs 35.7% control, aRR 0.14 [95% CI 0.08-0.26] p < 0.001). Prevalence of anaemia and mean haemoglobin were similar in both study arms.

CONCLUSIONS

School-aged children are a major reservoir of malaria parasites. Delivering IPT to schoolchildren would benefit individual children and may reduce transmission. School-based IPT could help to intensify malaria control toward elimination, and should be considered for policies and programmes. Trial registration Clinicaltrials.gov (NCT02009215), Registered 11 December 2013. https://clinicaltrials.gov/ct2/show/NCT02009215.

LLIN Evaluation in Uganda Project (LLINEUP): factors associated with childhood parasitaemia and anaemia 3 years after a national long-lasting insecticidal net distribution campaign: a cross-sectional survey

Background

Recent reductions in malaria burden have been attributed largely to long-lasting insecticidal nets (LLINs). In March–June 2017, approximately 3 years after a national LLIN distribution campaign, a cross-sectional community survey was conducted to investigate factors associated with malaria parasitaemia and anaemia, in advance of Uganda’s 2017–2018 LLIN campaign.

Methods

Households from 104 clusters in 48 districts were randomly selected using two-staged cluster sampling; 50 households were enrolled per cluster. Eligible children aged 2–10 years had blood obtained for a thick blood smear and those aged 2–4 years had haemoglobin measured. Associations between outcomes and variables of interest were assessed using log-binomial regression with generalized estimating equations to adjust for household clustering.

Results

In total, 5196 households, 8834 children with blood smear results, and 3753 with haemoglobin results were included. Only 16% of children lived in households with adequate LLIN coverage. Overall, parasite prevalence was 26.0%, ranging from 8.0% in the South West to 53.1% in East Central. Limiting data to children 2–4 years of age, parasite prevalence was 21.4%, up from 16.9% in 2014–2015 following the national LLIN campaign. In a multivariate analysis, factors associated with parasitaemia included region (East-Central vs South-Western; adjusted prevalence ratio [aPR] 6.45, 95% CI 5.55–7.50; p < 0.001), older age (8–10 vs 2–3 years; aPR 1.57, 95% CI 1.43–1.72; p < 0.001), living in a poorer household (poorest vs least poor tercile; aPR 2.32, 95% CI 2.05–2.63; p < 0.001), one constructed of traditional materials (aPR 1.13, 95% CI 1.03–1.24; p = 0.008), or without adequate LLIN coverage (aPR 1.30, 95% CI 1.14–1.48; p < 0.001). Overall, the prevalence of anaemia (haemoglobin < 10 g/dL) was 15.1% and varied geographically. In a multivariate analysis, factors associated with anaemia included region, younger age, living in a traditional house, and parasitaemia, which was the strongest predictor (aPR 2.50, 95% CI 2.12–2.95; p < 0.001).

Conclusions

Three years after a national LLIN campaign, LLIN coverage was low and parasite prevalence had increased. Parasite prevalence varied widely across Uganda; older children, those living in poorer households, and those with inadequate LLIN coverage, were at highest risk of parasitaemia. LLINs may need to be distributed more frequently through mass campaigns or continuously through sustainable mechanisms. Targeting interventions to geographic areas and populations at highest risk should also be considered.

Prevalence and clinical outcomes of Plasmodium falciparum and intestinal parasitic infections among children in Kiryandongo refugee camp, mid-Western Uganda: a cross sectional study

Background

The prevalence of Plasmodium falciparum and Intestinal Parasitic Infections (IPIs) - with the corresponding pathogenesis among children remain uncertain. This study aimed at determining the prevalence and the outcomes (including anaemia) of the respective infections and co-infections. Anaemia is a condition in which the number of red blood cells transporting oxygen to the various body parts is not sufficient to meet the needs of the body.

Methods

This was a cross sectional study conducted among 476-refugee camp school children. Kato-Katz technique was used to screen stool samples for intestinal parasites. Microscopy was used for malaria testing while the portable Haemoglobin (Hb) calorimeter was used to measure haemoglobin concentration.

Results

The overall prevalence of the mixed infections was 63.03%. Plasmodium falciparum was most prevalent of the single infections 262(55.04%) followed by Taenia spp. 14 (2.9%), Schistosoma mansoni 12(2.5%), Giardia lamblia 7 (2.9%), Trichuris trichiura 2(0.4%), Hookworm 2(0.4%) and Strongyloides stercoralis 1(0.2%). The odds of developing simple or uncomplicated malaria infection or anaemia was 14 times higher in individuals with dual co-infection with Plasmodium falciparum + Taenia sp. compared to single parasitic infection (Odds = 14.13, P = 0.019). Co-infection with Plasmodium falciparum + Taenia spp, was a strong predictor of Malaria and anaemia.

Conclusion

This study shows that Plasmodium falciparum and Taenia spp. co-infections is a stronger predictor of malaria and anaemia. The prevalence of malaria and anaemia remains higher than the other regions in Uganda outside restricted settlements. The findings of this study underline the need for pragmatic intervention programmes to reduce burden of the co-infections in the study area and similar settlements.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-3939-x) contains supplementary material, which is available to authorized users.

Community perceptions of paediatric severe anaemia in Uganda

Background

Severe anaemia remains a major cause of morbidity and mortality among children in sub-Saharan Africa. There is limited research on the beliefs and knowledge for paediatric severe anaemia in the region. The effect of these local beliefs and knowledge on the healthcare seeking of paediatric severe anaemia remains unknown.

Objective

To describe community perceptions of paediatric severe anaemia in Uganda.

Methods

Sixteen in-depth interviews of caregivers of children treated for severe anaemia and six focus group discussions of community members were conducted in three regions of Uganda between October and November 2017.

Results

There was no common local name used to describe paediatric severe anaemia, but the disease was understood in context as ‘having no blood’. Severe anaemia was identified to be a serious disease and the majority felt blood transfusion was the ideal treatment, but concomitant use of traditional and home remedies was also widespread. Participants articulated signs of severe pediatric anemia, such as palmar, conjunctival, and tongue pallor. Other signs described included jaundice, splenomegaly, difficulty in breathing and poor appetite. Poor feeding, malaria, splenomegaly and evil spirits were perceived to be the common causes of severe anaemia. Other causes included: human immunodeficiency virus (HIV), haemoglobinuria, fever, witchcraft, mosquito bites, and sickle cell. Splenomegaly and jaundice were perceived to be both signs and causes of severe anaemia. Severe anaemia was interpreted to be caused by evil spirits if it was either recurrent, led to sudden death, or manifested with cold extremities.

Conclusion

The community in Uganda perceived paediatric severe anaemia as a serious disease. Their understanding of the signs and perceived causes of severe anaemia to a large extent aligned with known clinical signs and biological causes. Belief in evil spirits persists and may be one obstacle to seeking timely medical care for paediatric severe anaemia.

Coinfection of intestinal schistosomiasis and malaria and association with haemoglobin levels and nutritional status in school children in Mara region, Northwestern Tanzania: a cross-sectional exploratory study

Background

Schistosomiasis represents a major public health problem in Tanzania despite ongoing national control efforts. This study examined whether intestinal schistosomiasis is associated with malaria and assessed the contribution of intestinal schistosomiasis and malaria on anaemia and undernutrition in school children in Mara region, North-western Tanzania.

Methods

Stool samples were collected from each of 928 school children randomly selected from 5 schools and examined for intestinal schistosomiasis using the Kato Katz method. Finger prick blood samples were collected and examined for malaria parasites and haemoglobin concentrations using the Giemsa stain and Haemocue methods, respectively. Nutritional status was assessed by taking anthropometric measurements.

Results

The overall prevalence and infection intensity of S. mansoni was 85.6% (794/928) and 192 (100–278), respectively. The prevalence of malaria was 27.4% (254/928) with significant differences among villages (χ² = 96.11, p < 0.001). The prevalence of anaemia was 42.3% (392/928) with significant differences among villages (χ² = 39.61, p < 0.001). The prevalence of stunting, thinness and underweight was 21, 6.8 and 1.3%, respectively. Stunting varied significantly by sex (χ² = 267.8, p < 0.001), age group (χ² = 96.4, p < 0.001) and by village (χ² = 20.5, p < 0.001). Out of the 825 infected children, 217 (26.4%) had multiple parasite infections (two to three parasites). The prevalence of co-infections occurred more frequently in boys than in girls (χ² = 21.65, p = 0.010). Mean haemoglobin concentrations for co-infected children was significantly lower than that of children not co-infected (115.2 vs 119.6; t = 0.01, p = 0.002). Co-infected children were more likely to be stunted than children who were not co-infected (χ² = 11.6, p = 0.003). On multivariate analysis, age group, village of residence and severe anaemia were significant predictors of stunting after adjusting for sex and infection status.

Conclusions

Intestinal schistosomiasis and malaria are prevalent in Mara region. Coinfections of these parasites as well as chronic undernutrition were also common. We recommend Mara region to be included in national schistosomiasis control programmes.

Multiplex Serologic Assessment of Schistosomiasis in Western Kenya: Antibody Responses in Preschool Aged Children as a Measure of Reduced Transmission

Currently, impact of schistosomiasis control programs in Schistosoma mansoni–endemic areas is monitored primarily by assessment of parasitologic indicators only. Our study was conducted to evaluate the use of antibody responses as a way to measure the impact of schistosomiasis control programs. A total of 3,612 serum samples collected at three time points from children 1–5 years of age were tested for antibody responses to two schistosome antigens (soluble egg antigen [SEA] and Sm25) by multiplex bead assay. The overall prevalence of antibody responses to SEA was high at baseline (50.0%). After one round of mass drug administration (MDA), there was minimal change in odds of SEA positivity (odds ratio [OR] = 1.02, confidence interval [CI] = 0.79–1.32, P = 0.89). However, after two rounds of treatment, there was a slight decrease in odds of SEA positivity (OR = 0.80, CI = 0.63–1.02, P = 0.08). In contrast to the SEA results, prevalence of antibody responses to Sm25 was lowest at baseline (14.1%) and higher in years 2 (19.8%) and 3 (18.4%). After one round of MDA, odds of Sm25 positivity increased significantly (OR = 1.51, CI = 1.14–2.02, P = 0.005) and remained significantly higher than baseline after two rounds of MDA (OR = 1.37, CI = 1.07–1.76, P = 0.01). There was a significant decrease in the proportion of 1-year-olds with positive SEA responses from 33.1% in year 1 to 13.2% in year 3 and a corresponding decrease in the odds (OR = 3.25, CI = 1.75–6.08, P < 0.001). These results provide preliminary evidence that schistosomiasis program impact can be monitored using serologic responses.

Prevalence of Anaemia and Associated Risk Factors among Children in North-western Uganda: A Cross Sectional Study

Background

Despite the public health significance of anaemia in African children, its broader and often preventable risk factors remain largely under described. This study investigated, for the first time, the prevalence of childhood anaemia and its risk factors in an urban setting in Uganda.

Methods

A total of 342 children were enrolled. Venous blood samples were collected in EDTA tubes and analyzed using Symex 500i (Symex Corp. Japan). Stool and urine samples were analyzed according to established standard methods. Anthropometric indicators were calculated according to the CDC/WHO 1978 references. Ethical approval was granted.

Results

Categorically, the prevalence of anaemia was; 37.2, 33.3 and 11.8% among children aged 1–5 years, 6–11 years and 12–14 years respectively. Overall anaemia prevalence was 34.4%. The risk of anaemia was higher among males than females [(OR = 1.3, 95% CI = 0.8, 2.1), P = .22]. Malaria was associated with a 1.5 times risk of anaemia though not statistically significant in the multivariate analysis (P = .19). Maternal parity <5 (P = .002), and stunting [(OR = 2.5, 95% CI = 1.3, 4.7), P = .004] were positively associated with anaemia. There was a positive correlation between household size and income (Pearson X² = 22.96; P = .001), implying that large families were of higher socioeconomic status.

Conclusions

This study demonstrates that anaemia is more prevalent in the under-5 age. The risk factors are stunting and low maternal parity. Interventions that address nutritional deficiencies in both pre-school and school children are recommended. Malaria and helminthiasis control measures counter the risk of anaemia. Further studies are required to investigate the association between maternal parity and anaemia found in this study.

Coinfection with Schistosoma haematobium and Plasmodium falciparum and Anaemia Severity among Pregnant Women in Munyenge, Mount Cameroon Area: A Cross-Sectional Study

Background. Malaria and urogenital schistosomiasis are coendemic in Mount Cameroon Area. This study investigated the prevalence of S. haematobium, P. falciparum, and coinfections and their effect on anaemia in pregnancy. Methods. Pregnant women reporting for antenatal care (ANC) clinic visit in Munyenge were enrolled. S. haematobium and P. falciparum infections were determined by urine filtration and microscopy, respectively. Haemoglobin (Hb) levels were measured using haemoglobinometer. Of 250 women, 46.8%, 39.2%, and 15.2% had S. haematobium, P. falciparum, and coinfections, respectively. Schistosomes infection was higher in younger women (≤25 years) and those who bathe in and had domestic contact with stream compared with older age (>25 years) women and those who had only domestic contact with stream. Lower infection rate was associated with less water contact (≤2 times/day) compared with more water contact (>2 times/day). Compared with no sulphadoxine-pyrimethamine (SP) usage, malaria parasitaemia was less among women who used SP. Stream usage increased risk of coinfection while less water contact and SP usage decreased its risk. All coinfected cases were anaemic and coinfection accounted for 93.8% of severe anaemia. Conclusion. Coinfection contributes to anaemia severity. Less water contact and SP usage will reduce coinfection in pregnancy in Munyenge.

An extensive burden of giardiasis associated with intestinal schistosomiasis and anaemia in school children on the shoreline of Lake Albert, Uganda

BACKGROUND

Water-borne parasitic diseases associated with poverty still blight the lives of African school children. In Uganda, intestinal schistosomiasis is still common along the shoreline of Lake Albert, despite ongoing control, and co-infection with giardiasis and malaria is poorly described. To shed light on putative interactions between diseases, a prospective cross-sectional parasitological survey was undertaken in five primary schools.

METHODS

Stool samples from 254 school children, aged 5-10 years, were examined by microscopy and rapid diagnostic tests (RDTs), with additional real-time PCR assays for detection of Giardia DNA. A finger-prick blood sample was also taken from each child and tested for malaria, and haemoblobin levels measured. Assocations between diseases and anaemia were assessed.

RESULTS

Intestinal schistosomiasis (46.5%), giardiasis (41.6%) and malaria (56.2%) were common, and a quarter of children were anaemic (<115 g/L). Up to 87.0% of children were excreting Giardia DNA and the prevalence of heavy infection by real-time PCR (Ct≤19) was 19.5%, being positively associated with light, moderate and heavy egg-patent schistosomiasis, as well as with anaemia.

CONCLUSIONS

In this setting, an extensive burden of giardiasis was revealed with heavy intensity infections associated with egg-patent intestinal schistosomiasis and anaemia. To improve child health, greater attention on giardiasis is needed along with exploring joined-up actions across diseases that promote better water hygiene and sanitation measures.

Severe anaemia associated with Plasmodium falciparum infection in children: consequences for additional blood sampling for research

BACKGROUND

Plasmodium falciparum infection may cause severe anaemia, particularly in children. When planning a diagnostic study on children suspected of severe malaria in sub-Saharan Africa, it was questioned how much blood could be safely sampled; intended blood volumes (blood cultures and EDTA blood) were 6 mL (children aged <6 years) and 10 mL (6-12 years). A previous review [Bull World Health Organ. 89: 46-53. 2011] recommended not to exceed 3.8 % of total blood volume (TBV). In a simulation exercise using data of children previously enrolled in a study about severe malaria and bacteraemia in Burkina Faso, the impact of this 3.8 % safety guideline was evaluated.

METHODS

For a total of 666 children aged >2 months to <12 years, data of age, weight and haemoglobin value (Hb) were available. For each child, the estimated TBV (TBVe) (mL) was calculated by multiplying the body weight (kg) by the factor 80 (ml/kg). Next, TBVe was corrected for the degree of anaemia to obtain the functional TBV (TBVf). The correction factor consisted of the rate 'Hb of the child divided by the reference Hb'; both the lowest ('best case') and highest ('worst case') reference Hb values were used. Next, the exact volume that a 3.8 % proportion of this TBVf would present was calculated and this volume was compared to the blood volumes that were intended to be sampled.

RESULTS

When applied to the Burkina Faso cohort, the simulation exercise pointed out that in 5.3 % (best case) and 11.4 % (worst case) of children the blood volume intended to be sampled would exceed the volume as defined by the 3.8 % safety guideline. Highest proportions would be in the age groups 2-6 months (19.0 %; worst scenario) and 6 months-2 years (15.7 %; worst case scenario). A positive rapid diagnostic test for P. falciparum was associated with an increased risk of violating the safety guideline in the worst case scenario (p = 0.016).

CONCLUSIONS

Blood sampling in children for research in P. falciparum endemic settings may easily violate the proposed safety guideline when applied to TBVf. Ethical committees and researchers should be wary of this and take appropriate precautions.

Malaria, anaemia and under-nutrition: three frequently co-existing conditions among preschool children in rural Rwanda

Background

Malaria, anaemia and under-nutrition are three highly prevalent and frequently co-existing diseases that cause significant morbidity and mortality particularly among children aged less than 5 years. Currently, there is paucity of conclusive studies on the burden of and associations between malaria, anaemia and under-nutrition in Rwanda and comparable sub-Saharan and thus, this study measured the prevalence of malaria parasitaemia, anaemia and under-nutrition among preschool age children in a rural Rwandan setting and evaluated for interactions between and risk determinants for these three conditions.

Methods

A cross-sectional household (HH) survey involving children aged 6–59 months was conducted. Data on malaria parasitaemia, haemoglobin densities, anthropometry, demographics, socioeconomic status (SES) and malaria prevention knowledge and practices were collected.

Results

The prevalences of malaria parasitaemia and anaemia were 5.9 and 7.0 %, respectively, whilst the prevalence of stunting was 41.3 %. Malaria parasitaemia risk differed by age groups with odds ratio (OR) = 2.53; P = 0.04 for age group 24–35 months, OR = 3.5; P = 0.037 for age group 36–47 months, and OR = 3.03; P = 0.014 for age group 48–60 months, whilst a reduced risk was found among children living in high SES HHs (OR = 0.37; P = 0.029). Risk of anaemia was high among children aged ≥12 months, those with malaria parasitaemia (OR = 3.86; P ≤ 0.0001) and children living in HHs of lower SES. Overall, under-nutrition was not associated with malaria parasitaemia. Underweight was higher among males (OR = 1.444; P = 0.019) and children with anaemia (OR = 1.98; P = 0.004).

Conclusions

In this study group, four in 10 and one in 10 children were found stunted and underweight, respectively, in an area of low malaria transmission. Under-nutrition was not associated with malaria risk. While the high prevalence of stunting requires urgent response, reductions in malaria parasitaemia and anaemia rates may require, in addition to scaled-up use of insecticide-treated bed nets and indoor residual insecticide spraying, improvements in HH SES and better housing to reduce risk of malaria.

Influence of Schistosoma mansoni and Hookworm Infection Intensities on Anaemia in Ugandan Villages

BACKGROUND

The association of anaemia with intestinal schistosomiasis and hookworm infections are poorly explored in populations that are not limited to children or pregnant women.

METHODS

We sampled 1,832 individuals aged 5-90 years from 30 communities in Mayuge District, Uganda. Demographic, village, and parasitological data were collected. Infection risk factors were compared in ordinal logistic regressions. Anaemia and infection intensities were analyzed in multilevel models, and population attributable fractions were estimated.

FINDINGS

Household and village-level predictors of Schistosoma mansoni and hookworm were opposite in direction or significant for single infections. S. mansoni was found primarily in children, whereas hookworm was prevalent amongst the elderly. Anaemia was more prevalent in individuals with S. mansoni and increased by 2.86 fold (p-value<0.001) with heavy S. mansoni infection intensity. Individuals with heavy hookworm were 1.65 times (p-value = 0.008) more likely to have anaemia than uninfected participants. Amongst individuals with heavy S. mansoni infection intensity, 32.0% (p-value<0.001) of anaemia could be attributed to S. mansoni. For people with heavy hookworm infections, 23.7% (p-value = 0.002) of anaemia could be attributed to hookworm. A greater fraction of anaemia (24.9%, p-value = 0.002) was attributable to heavy hookworm infections in adults (excluding pregnant women) as opposed to heavy hookworm infections in school-aged children and pregnant women (20.2%, p-value = 0.001).

CONCLUSION

Community-based surveys captured anaemia in children and adults affected by S. mansoni and hookworm infections. For areas endemic with schistosomiasis or hookworm infections, WHO guidelines should include adults for treatment in helminth control programmes.

Prevalence and factors associated with severe anaemia amongst under-five children hospitalized at Bugando Medical Centre, Mwanza, Tanzania

Background

Anaemia is a major public health problem in developing countries, contributing significantly to morbidity and mortality amongst children under-five years of age. About 43 % of under-fives are anaemic worldwide, and two-thirds reside in sub-Saharan Africa. Even where blood transfusion is available for treatment there is still a significant case fatality rate ranging between 6 and 18 %. This study aimed to determine the prevalence and morphological types of anaemia, as well as factors associated with severe anaemia in under-five children admitted at Bugando Medical Centre (BMC).

Methods

This was a hospital-based, cross-sectional study conducted between November 2012 and February 2013. Selected laboratory investigations were done on children admitted to BMC. Anaemia was defined using WHO criteria.

Results

A total of 448 under-five children were recruited into the study. The overall prevalence of anaemia was 77.2 % (346/448) with mild, moderate and severe anaemia being 16.5, 33 and 27.7 % respectively. Microcytic hypochromic anaemia was detected in 37.5 % of the children with anaemia. Of 239 children with moderate and severe anaemia, 22.6 % (54/239) had iron deficiency anaemia based on serum ferritin level less than12 μg/ml. The factors associated with severe anaemia included unemployment of the parent, malaria parasitaemia and presence of sickle haemoglobin.

Conclusion

The prevalence of anaemia among under-five children admitted at BMC was high. Iron deficiency anaemia was the most common type. Factors associated with severe anaemia were unemployment among caretakers, malaria parasitaemia and presence of sickle haemoglobin.

Factors associated with malaria parasitemia, anemia and serological responses in a spectrum of epidemiological settings in Uganda

Background

Understanding the current epidemiology of malaria and the relationship between intervention coverage, transmission intensity, and burden of disease is important to guide control activities. We aimed to determine the prevalence of anemia, parasitemia, and serological responses to P. falciparum antigens, and factors associated with these indicators, in three different epidemiological settings in Uganda.

Methods and Findings

In 2012, cross-sectional surveys were conducted in 200 randomly selected households from each of three sites: Walukuba, Jinja district (peri-urban); Kihihi, Kanungu district (rural); and Nagongera, Tororo district (rural) with corresponding estimates of annual entomologic inoculation rates (aEIR) of 3.8, 26.6, and 125.0, respectively. Of 2737 participants, laboratory testing was done in 2227 (81.4%), including measurement of hemoglobin, parasitemia using microscopy, and serological responses to P. falciparum apical membrane antigen 1 (AMA-1) and merozoite surface protein 1, 19 kilodalton fragment (MSP-1₁₉). Analysis of laboratory results was restricted to 1949 (87.5%) participants aged ≤ 40 years. Prevalence of anemia (hemoglobin < 11.0 g/dL) was significantly higher in Walukuba (18.9%) and Nagongera (17.4%) than in Kihihi (13.1%), and was strongly associated with decreasing age for those ≤ 5 years at all sites. Parasite prevalence was significantly higher in Nagongera (48.3%) than in Walukuba (12.2%) and Kihihi (12.8%), and significantly increased with age to 11 years, and then significantly decreased at all sites. Seropositivity to AMA-1 was 53.3% in Walukuba, 63.0% in Kihihi, and 83.7% in Nagongera and was associated with increasing age at all sites. AMA-1 seroconversion rates strongly correlated with transmission intensity, while serological responses to MSP-1₁₉ did not.

Conclusion

Anemia was predominant in young children and parasitemia peaked by 11 years across 3 sites with varied transmission intensity. Serological responses to AMA-1 appeared to best reflect transmission intensity, and may be a more accurate indicator for malaria surveillance than anemia or parasitemia.

Morbidity associated with schistosomiasis before and after treatment in young children in Rusinga Island, western Kenya

Schistosoma mansoni infection is a major cause of organomegaly and ultimately liver fibrosis in adults. Morbidity in pre-school-aged children is less defined, and they are currently not included in mass drug administration (MDA) programs for schistosomiasis control. We report results of a study of the association of schistosomiasis with organomegaly in a convenience sample of 201 children under 7 years old in Rusinga, Kenya on two cross-sectional visits, before and after praziquantel treatment. Data included stool examination and serology for schistosomiasis, the Niamey ultrasound protocol to stage hepatosplenic morbidity including organomegaly, and potential confounders including malaria. Unadjusted and adjusted Poisson regressions were performed. The baseline prevalence of schistosomiasis by antibody and/or stool was 80.3%. Schistomiasis was associated with hepatomegaly (adjusted prevalence ratio [aPR] = 1.4; 95% confidence interval [CI]: 1.0-2.1) and splenomegaly (aPR = 2.1; 95% CI: 1.2-3.7). The association with hepatomegaly persisted posttreatment (aPR = 1.4; 95% CI: 1.1-1.6). Schistosomiasis was associated with morbidity in this cohort. Efforts to include young children in mass treatment campaigns should intensify.

Diagnostics for schistosomiasis in Africa and Arabia: a review of present options in control and future needs for elimination

Within the World Health Organization 2012-2020 roadmap for control and elimination of schistosomiasis, the scale-up of mass drug administration with praziquantel is set to change the epidemiological landscape across Africa and Arabia. Central in measuring progress is renewed emphasis upon diagnostics which operate at individual, community and environmental levels by assessing reductions in disease, infections and parasite transmission. However, a fundamental tension is revealed between levels for present diagnostic tools, and methods applied in control settings are not necessarily adequate for application in elimination scenarios. Indeed navigating the transition from control to elimination needs careful consideration and planning. In the present context of control, we review current options for diagnosis of schistosomiasis at different levels, highlighting several strengths and weaknesses therein. Future challenges in elimination are raised and we propose that more cost-effective diagnostics and clinical staging algorithms are needed. Using the Kingdom of Saudi Arabia as a contemporary example, embedding new diagnostic methods within the primary care health system is discussed with reference to both urogenital and intestinal schistosomiasis.

Can an integrated approach reduce child vulnerability to anaemia? Evidence from three African countries

Addressing the complex, multi-factorial causes of childhood anaemia is best done through integrated packages of interventions. We hypothesized that due to reduced child vulnerability, a "buffering" of risk associated with known causes of anaemia would be observed among children living in areas benefiting from a community-based health and nutrition program intervention. Cross-sectional data on the nutrition and health status of children 24-59 mo (N=2405) were obtained in 2000 and 2004 from program evaluation surveys in Ghana, Malawi and Tanzania. Linear regression models estimated the association between haemoglobin and immediate, underlying and basic causes of child anaemia and variation in this association between years. Lower haemoglobin levels were observed in children assessed in 2000 compared to 2004 (difference -3.30 g/L), children from Tanzania (-9.15 g/L) and Malawi (-2.96 g/L) compared to Ghana, and the youngest (24-35 mo) compared to oldest age group (48-59 mo; -5.43 g/L). Children who were stunted, malaria positive and recently ill also had lower haemoglobin, independent of age, sex and other underlying and basic causes of anaemia. Despite ongoing morbidity, risk of lower haemoglobin decreased for children with malaria and recent illness, suggesting decreased vulnerability to their anaemia-producing effects. Stunting remained an independent and unbuffered risk factor. Reducing chronic undernutrition is required in order to further reduce child vulnerability and ensure maximum impact of anaemia control programs. Buffering the impact of child morbidity on haemoglobin levels, including malaria, may be achieved in certain settings.

Randomized, controlled, assessor-blind clinical trial to assess the efficacy of single- versus repeated-dose albendazole to treat ascaris lumbricoides, trichuris trichiura, and hookworm infection

In many regions where soil-transmitted helminth infections are endemic, single-dose albendazole is used in mass drug administration programs to control infections. There are little data on the efficacy of the standard single-dose administration compared to that of alternative regimens. We conducted a randomized, controlled, assessor-blinded clinical trial to determine the efficacies of standard and extended albendazole treatment against soil-transmitted helminth infection in Gabon. A total of 175 children were included. Adequate cure rates and egg reduction rates above 85% were found with a single dose of albendazole for Ascaris infection, 85% (95% confidence interval [CI], 73, 96) and 93.8% (CI, 87.6, 100), respectively, while two doses were necessary for hookworm infestation (92% [CI, 78, 100] and 92% [CI, 78, 100], respectively). However, while a 3-day regimen was not sufficient to cure Trichuris (cure rate, 83% [CI, 73, 93]), this regimen reduced the number of eggs up to 90.6% (CI, 83.1, 100). The rate ratios of two- and three-dose regimens compared to a single-dose treatment were 1.7 (CI, 1.1, 2.5) and 2.1 (CI, 1.5, 2.9) for Trichuris and 1.7 (CI, 1.0, 2.9) and 1.7 (CI, 1.0, 2.9) for hookworm. Albendazole was safe and well tolerated in all regimens. A single-dose albendazole treatment considerably reduces Ascaris infection but has only a moderate effect on hookworm and Trichuris infections. The single-dose option may still be the preferred regimen because it balances efficacy, safety, and compliance during mass drug administration, keeping in mind that asymptomatic low-level helminth carriage may also have beneficial effects. (This study has been registered at ClinicalTrials.gov under registration number NCT01192802.).

Progress in paediatric parasitology: a preface to a topic focusing on ever younger subjects

Without realizing it perhaps, the research activities of many parasitologists are often focused upon the study of parasites most commonly found in children. Though there is little recognition of paediatric parasitology as a separate topic within medical parasitology, with the global interest in promotion of maternal and child health, alleviation of diseases associated with poverty and requirements of 'child-sized' medicines, a more formal consideration is now timely. Recent research, for example, has highlighted that defining precisely the 'first-age' at which parasites interfere with a child's health, or normal developmental processes, is being revised. Attention is now drawn towards ever younger subjects, for parasites have the capacity to also influence the health of the foetus within the in utero environment, altering immune-development. These subtle, yet evolutionary profound interactions perhaps manifest themselves as to why some children are more prone to infection(s), develop overt disease and sadly die while others do not. Here, we address the growing importance of paediatric parasitology and its applications within disease control strategies as highlighted in the 2010 Autumn Symposium of the British Society of Parasitology.

New insights into the molecular epidemiology and population genetics of Schistosoma mansoni in Ugandan pre-school children and mothers

Significant numbers of pre-school children are infected with Schistosoma mansoni in sub-Saharan Africa and are likely to play a role in parasite transmission. However, they are currently excluded from control programmes. Molecular phylogenetic studies have provided insights into the evolutionary origins and transmission dynamics of S. mansoni, but there has been no research into schistosome molecular epidemiology in pre-school children. Here, we investigated the genetic diversity and population structure of S. mansoni in pre-school children and mothers living in lakeshore communities in Uganda and monitored for changes over time after praziquantel treatment. Parasites were sampled from children (<6 years) and mothers enrolled in the longitudinal Schistosomiasis Mothers and Infants Study at baseline and at 6-, 12- and 18-month follow-up surveys. 1347 parasites from 35 mothers and 45 children were genotyped by direct sequencing of the cytochrome c oxidase (cox1) gene. The cox1 region was highly diverse with over 230 unique sequences identified. Parasite populations were genetically differentiated between lakes and non-synonymous mutations were more diverse at Lake Victoria than Lake Albert. Surprisingly, parasite populations sampled from children showed a similar genetic diversity to those sampled from mothers, pointing towards a non-linear relationship between duration of exposure and accumulation of parasite diversity. The genetic diversity six months after praziquantel treatment was similar to pre-treatment diversity. Our results confirm the substantial genetic diversity of S. mansoni in East Africa and provide significant insights into transmission dynamics within young children and mothers, important information for schistosomiasis control programmes.

Many pre-school children in sub-Saharan Africa are infected with the parasite Schistosoma mansoni, which causes intestinal schistosomiasis. However, there has been no work published on the molecular epidemiology of Schistosoma in children under six or the role that these children play in parasite transmission. We analysed the genetic structure of parasite populations collected from mothers and young children living on the shores of Lakes Albert and Victoria in Uganda. Parasite populations were different at the two lakes indicating that there is little flow of parasite genes between the lakes. We were surprised to discover a large amount of genetic variation in parasites sampled from both children and mothers, suggesting that genetic variation is not directly related to duration of exposure to infested water. In addition, we found some evidence that young children are involved in S. mansoni transmission. The substantial genetic variation of S. mansoni in young children suggests that these parasites could be operating as a source of a variety of genetic traits, including drug susceptibility. Overall our findings offer significant insights into population genetics of S. mansoni in pre-school children and their mothers and provide important information for effective control of intestinal schistosomiasis.

Treatment of schistosomiasis in African infants and preschool-aged children: downward extension and biometric optimization of the current praziquantel dose pole

To facilitate administration of praziquantel (PZQ) to African infants and preschool-aged children using a dose pole, the performance of two downwardly extended versions (the first created in 2010 using biometric data from Uganda alone and the second version created here using data from 36 countries) was assessed against height/weight data from a total of 166 210 preschool-aged children (≤6 year olds) from 36 African countries. New and optimized thresholds for PZQ tablet administration at one tablet (600 mg), ¾ and ½ tablet divisions are suggested here. Both dose poles investigated estimated an acceptable PZQ dosage (30-60 mg/Kg) for more than 95% of children. Extension and optimization of the current PZQ dose pole, followed by theoretical validation using biometric data from preschool-aged children (0-6 years of age, 60-110 cm in height) from 36 African countries will help future mass drug administration campaigns incorporate younger children. This newly optimized dose pole with single 600 mg (height: 99-110 cm), ¾ (height: 83-99 cm) and ½ (height: 66-83 cm) tablet divisions, also reduces drug waste and facilitates inclusion of preschool-aged children. Our findings also have bearings on the use of other dose poles for treatment of young children.

Schistosomiasis in African infants and preschool children: let them now be treated!

The occurrence of schistosomiasis within African infants and preschool children has been much better documented in recent years, revealing an important burden of disease previously overlooked. Despite mounting evidence showing that treatment with praziquantel is safe, beneficial, and could be delivered within ongoing public health interventions, young children still do not have satisfactory access to this drug, and a significant treatment gap exists. Progress towards resolution of this unfortunate health inequity is highlighted, including the development of an appropriate paediatric praziquantel formulation, and present blocks are identified on securing this issue within the international health agenda.

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.

Use of fecal occult blood tests as epidemiologic indicators of morbidity associated with intestinal schistosomiasis during preventive chemotherapy in young children

There is a need for field-applicable markers to assess morbidity associated with intestinal schistosomiasis, especially in the context of preventive chemotherapy in young children. We investigated whether fecal occult blood (FOB) point-of-care tests could be used to assess intestinal pathology over a 12-month period in a cohort of 382 children (< 5 years of age). We found a strong association between egg-patent schistosomiasis and FOB at baseline (odds ratio [OR] = 3.1, P < 0.0001), 6 months (OR = 3.4, P < 0.0001), and 12 months (OR = 3.5, P < 0.0001), despite repeated chemotherapy. There were tendencies for prevalence of FOB to decrease in children who became egg negative and increase in those who became egg positive. Our results demonstrate overt disease in children less than five years of age. We therefore propose that FOB is useful for assessing dynamics of intestinal morbidity in young children at the community level and monitoring changes in morbidity after mass chemotherapy.

Real-time PCR demonstrates Ancylostoma duodenale is a key factor in the etiology of severe anemia and iron deficiency in Malawian pre-school children

BACKGROUND

Hookworm infections are an important cause of (severe) anemia and iron deficiency in children in the tropics. Type of hookworm species (Ancylostoma duodenale or Necator americanus) and infection load are considered associated with disease burden, although these parameters are rarely assessed due to limitations of currently used diagnostic methods. Using multiplex real-time PCR, we evaluated hookworm species-specific prevalence, infection load and their contribution towards severe anemia and iron deficiency in pre-school children in Malawi.

METHODOLOGY AND FINDINGS

A. duodenale and N. americanus DNA loads were determined in 830 fecal samples of pre-school children participating in a case control study investigating severe anemia. Using multiplex real-time PCR, hookworm infections were found in 34.1% of the severely anemic cases and in 27.0% of the non-severely anemic controls (p<0.05) whereas a 5.6% hookworm prevalence was detected by microscopy. Prevalence of A. duodenale and N. americanus was 26.1% and 4.9% respectively. Moderate and high load A. duodenale infections were positively associated with severe anemia (adjusted odds ratio: 2.49 (95%CI 1.16-5.33) and 9.04 (95%CI 2.52-32.47) respectively). Iron deficiency (assessed through bone marrow examination) was positively associated with intensity of A. duodenale infection (adjusted odds ratio: 3.63 (95%CI 1.18-11.20); 16.98 (95%CI 3.88-74.35) and 44.91 (95%CI 5.23-385.77) for low, moderate and high load respectively).

CONCLUSIONS/SIGNIFICANCE

This is the first report assessing the association of hookworm load and species differentiation with severe anemia and bone marrow iron deficiency. By revealing a much higher than expected prevalence of A. duodenale and its significant and load-dependent association with severe anemia and iron deficiency in pre-school children in Malawi, we demonstrated the need for quantitative and species-specific screening of hookworm infections. Multiplex real-time PCR is a powerful diagnostic tool for public health research to combat (severe) anemia and iron deficiency in children living in resource poor settings.

Association between anaemia, iron deficiency anaemia, neglected parasitic infections and socioeconomic factors in rural children of West Malaysia

BACKGROUND

Given that micronutrient deficiency, neglected intestinal parasitic infections (IPIs) and poor socioeconomic status are closely linked, we conducted a cross-sectional study to assess the relationship between IPIs and nutritional status of children living in remote and rural areas in West Malaysia.

METHODS/FINDINGS

A total of 550 children participated, comprising 520 (94.5%) school children aged 7 to 12 years old, 30 (5.5%) young children aged 1 to 6 years old, 254 (46.2%) boys and 296 (53.8%) girls. Of the 550 children, 26.2% were anaemic, 54.9% iron deficient and 16.9% had iron deficiency anaemia (IDA). The overall prevalence of helminths was 76.5% comprising Trichuris trichiura (71.5%), Ascaris lumbricoides (41.6%) and hookworm infection (13.5%). It was observed that iron deficiency was significantly higher in girls (p = 0.032) compared to boys. Univariate analysis demonstrated that low level of mother's education (OR = 2.52; 95% CI = 1.38-4.60; p = 0.002), non working parents (OR = 2.18; 95% CI = 2.06-2.31; p = 0.013), low household income (OR = 2.02; 95% CI = 1.14-3.59; p = 0.015), T. trichiura (OR = 2.15; 95% CI = 1.21-3.81; p = 0.008) and A. lumbricoides infections (OR = 1.63; 95% CI = 1.04-2.55; p = 0.032) were significantly associated with the high prevalence of IDA. Multivariate analysis confirmed that low level of mother's education (OR = 1.48; 95 CI% = 1.33-2.58; p<0.001) was a significant predictor for IDA in these children.

CONCLUSION

It is crucial that a comprehensive primary health care programme for these communities that includes periodic de-worming, nutrition supplement, improved household economy, education, sanitation status and personal hygiene are taken into consideration to improve the nutritional status of these children.