Urban malaria and anaemia in children: a cross-sectional survey in two cities of Ghana

Description of the design of a mixed-methods study to assess the burden and determinants of malaria transmission for tailoring of interventions (microstratification) in Ibadan and Kano metropolis

BACKGROUND

Rapid urbanization in Nigerian cities may lead to localized variations in malaria transmission, particularly with a higher burden in informal settlements and slums. However, there is a lack of available data to quantify the variations in transmission risk at the city level and inform the selection of appropriate interventions. To bridge this gap, field studies will be undertaken in Ibadan and Kano, two major Nigerian cities. These studies will involve a blend of cross-sectional and longitudinal epidemiological research, coupled with longitudinal entomological studies. The primary objective is to gain insights into the variation of malaria risk at the smallest administrative units, known as wards, within these cities.

METHODS/RESULTS

The findings will contribute to the tailoring of interventions as part of Nigeria's National Malaria Strategic Plan. The study design incorporates a combination of model-based clustering and on-site visits for ground-truthing, enabling the identification of environmental archetypes at the ward-level to establish the study's framework. Furthermore, community participatory approaches will be utilized to refine study instruments and sampling strategies. The data gathered through cross-sectional and longitudinal studies will contribute to an enhanced understanding of malaria risk in the metropolises of Kano and Ibadan.

CONCLUSIONS

This paper outlines pioneering field study methods aimed at collecting data to inform the tailoring of malaria interventions in urban settings. The integration of multiple study types will provide valuable data for mapping malaria risk and comprehending the underlying determinants. Given the importance of location-specific data for microstratification, this study presents a systematic process and provides adaptable tools that can be employed in cities with limited data availability.

Malaria infection and anemia status in under-five children from Southern Tanzania where seasonal malaria chemoprevention is being implemented

BACKGROUND

Malaria and anemia remain major public health challenges in Tanzania. Household socioeconomic factors are known to influence these conditions. However, it is not clear how these factors influence malaria transmission and anemia in Masasi and Nanyumbu Districts. This study presents findings on malaria and anemia situation in under-five children and its influencing socioeconomic factors in Masasi and Nanyumbu Districts, surveyed as part of an ongoing seasonal malaria chemoprevention operational study.

METHODS

A community-based cross-sectional survey was conducted between August and September 2020. Finger-prick blood samples collected from children aged 3-59 months were used to test for malaria infection using malaria rapid diagnostic test (mRDT), thick smears for determination of asexual and sexual parasitemia, and thin smear for parasite speciation. Hemoglobin concentration was measured using a HemoCue spectrophotometer. A structured questionnaire was used to collect household socioeconomic information from parents/caregivers of screened children. The prevalence of malaria was the primary outcome. Chi-square tests, t-tests, and logistic regression models were used appropriately.

RESULTS

Overall mRDT-based malaria prevalence was 15.9% (373/2340), and was significantly higher in Nanyumbu (23.7% (167/705) than Masasi District (12.6% (206/1635), p<0.001. Location (Nanyumbu), no formal education, household number of people, household number of under-fives, not having a bed net, thatched roof, open/partially open eave, sand/soil floor, and low socioeconomic status were major risks for malaria infection. Some 53.9% (1196/2218) children had anemia, and the majority were in Nanyumbu (63.5% (458/705), p<0.001. Location (Nanyumbu), mRDT positive, not owning a bed net, not sleeping under bed net, open/partially open eave, thatched window, sex of the child, and age of the child were major risk factors for anemia.

CONCLUSION

Prevalence of malaria and anemia was high and was strongly associated with household socioeconomic factors. Improving household socioeconomic status is expected to reduce the prevalence of the conditions in the area.

Factors Associated with Anemia Status Among Children Aged 6-59 months in Ghana, 2003-2014

Background

In 2008, 78% of Ghanaian children under 5 years old were anemic versus 48% of children globally. In this study, we identified proximal and distal determinants of severe–moderate anemia and mild anemia related to socioeconomic status, nutrition, and health access.

Methods

Using data from the 2003, 2008, and 2014 Ghana Demographic and Health Surveys (GDHS), the odds of severe–moderate anemia and mild anemia compared to no anemia, in relation to various hypothesized risk factors, were assessed using a multivariable, multinomial logistic regression, which accounted for survey design.

Results

From among 7739 households sampled, severe–moderate anemia was found in approximately 52%, 56%, and 40% of children during 2003, 2008, and 2014, respectively. The proportion of children diagnosed as not anemic was 26% in 2003, 22% in 2008, and 33% in 2014. There are large disparities in anemia prevalence among regions and between urban and rural areas. In 2014, children who were younger (aged 6–24 months), had a recent fever, were from poorer families, and whose mothers were less educated had greater odds of being severely–moderately anemic. These results remained significant when controlling for other risk factors. Predictors of anemia in Ghana remained relatively consistent among the three time periods when the GDHS was administered.

Conclusions

The prevalence of anemia in Ghana among children aged 6–59 months has remained unacceptably high. To reduce anemia in these children, the Ghanaian government should concentrate on educating women through both the traditional school system and antenatal care visits.

Travel Is a Key Risk Factor for Malaria Transmission in Pre-Elimination Settings in Sub-Saharan Africa: A Review of the Literature and Meta-Analysis

By sustaining transmission or causing malaria outbreaks, imported malaria undermines malaria elimination efforts. Few studies have examined the impact of travel on malaria epidemiology. We conducted a literature review and meta-analysis of studies investigating travel as a risk factor for malaria infection in sub-Saharan Africa using PubMed. We identified 22 studies and calculated a random-effects meta-analysis pooled odds ratio (OR) of 3.77 (95% CI: 2.49–5.70), indicating that travel is a significant risk factor for malaria infection. Odds ratios were particularly high in urban locations when travel was to rural areas, to more endemic/high transmission areas, and in young children. Although there was substantial heterogeneity in the magnitude of association across the studies, the pooled estimate and directional consistency support travel as an important risk factor for malaria infection.

Implication of Anopheles funestus in malaria transmission in the city of Yaoundé, Cameroon

The contribution of Anopheles funestus to malaria transmission in the urban environment is still not well documented. The present study assesses the implication of An. funestus in malaria transmission in two districts, Nsam and Mendong, in the city of Yaoundé. Adult mosquitoes were collected using Centers for Disease Control and Prevention miniature light traps (CDC-LT) and human landing catches from April 2017 to March 2018 and were identified morphologically to the species level. Those belonging to the Anopheles gambiae complex and to the Anopheles funestus group were further processed by PCR to identify members of each complex/group. Anopheline mosquitoes were analysed to determine their infection status using an enzyme-linked immunosorbent assay. Bioassays were conducted with 2–5-day-old female Anopheles funestus and An. gambiae s.l. to determine their susceptibility to permethrin, deltamethrin and dichlorodiphenyltrichloroethane (DDT). Six anopheline species were collected in the peri-urban district of Mendong: Anopheles gambiae, An. coluzzii, An. funestus, An. leesoni, An. ziemanni and An. marshallii; only four out of the six were recorded in Nsam. Of the two members of the Anopheles gambiae complex collected, An. coluzzii was the most prevalent. Anopheles coluzzii was the most abundant species in Nsam, while An. funestus was the most abundant in Mendong. Both Anopheles funestus and An. gambiae s.l. were found to be infected with human Plasmodium at both sites, and both were found to be resistant to DDT, permethrin, and deltamethrin. This study confirms the participation of An. funestus in malaria transmission in Yaoundé and highlights the need to also target this species for sustainable control of malaria transmission.

Prevalence of anemia and associated factors in children living in urban and rural settings from Bata District, Equatorial Guinea, 2013

Anemia in children under 5 years of age is a global public health problem. According to the World Health Organization the current rate of anemia among preschool aged children in Equatorial Guinea is 66%. No information is available above this age. The cross-sectional Prevamal Survey was conducted in 2013 aimed at providing baseline data on malaria prevalence in children aged 2 months-15 years old. Sampling was carried out with the use of a multistage, stratified cluster strategy in the district of Bata, Equatorial Guinea. The χ2 test and adjusted Poisson regression models were applied to assess the association between social-demographic and economic factors, malaria and anemia. A total of 1436 children were tested, out of which 1,421 children (99%) were tested for anemia. Over 85% were anemic; out of them, 284 (24%), 815 (67%) and 111 (9%) children had mild, moderate and severe anemia, respectively. Severe anemia was more frequent among children aged 2–12 months old and those living in rural sites. About 47% tested positive for malaria via a rapid diagnostic test (RDT). This rate was significantly higher in rural villages (66%; p<0.001). The prevalence of anemia and malaria was higher in rural settings (p<0.001). On the other hand, anemia in urban areas displayed a heterogeneity and complexity that differed from the rural environment: in urban neighbourhoods, children with concomitant malaria infection were more likely to be anemic (adjusted prevalence rate (aPR):1.19; CI 95%: 1.12–1.28). Moreover, the prevalence of anemia was higher in children aged above 13 months compared to younger children (p<0.005). Belonging to the poorest wealth tertile were positively (aPR: 1.14, 95% CI: 1.05–1.24) and children’ parents being employees (aPR: 0.86, 95% CI: 0.76–0.96) or self-employed (aPR: 0.86, 95% CI: 0.76–0.97) vs. working in agriculture and/or fishing negatively associated with anemia among urban children. This marked urban-rural variation indicates the importance of targeting specific areas or districts. Strategies aimed at reducing malaria are clearly paramount in this country. Prevention and treatment of other factors associated with the etiology of anemia (e.g., iron deficiency) are also likely necessary to combat the burden of anemia in Equatorial Guinea.

Hematological Differences among Malaria Patients in Rural and Urban Ghana

BACKGROUND

Scarce studies have addressed hematological differences of malaria in urban and rural regions.

METHODS

Full or complete blood cell counts from 46 and 75 individuals (age range from < 1 to 92 years) with uncomplicated malaria infection living in urban (Accra) and rural (Dodowa) Ghana, respectively, were assessed. Sickle cell trait and patients were excluded from the study.

RESULTS

Between overall groups, patients from Accra had significantly lower parasite count (p < 0.0001) and granulocyte number (p = 0.026). Children in Accra had a significantly lower parasitemia (p = 0.0013), hemoglobin (p = 0.0254), platelet count (p = 0.0148) and red blood cell levels (p = 0.0080) when compared with the children of Dodowa. In adults, mean cell hemoglobin (p = 0.0086) and parasite count (p < 0.0001) were significantly higher in Dodowa.

CONCLUSION

These results indicate that children living in urban setting may experience a greater anemic effect to malaria as compared with those living in a rural setting.

Spatiotemporal Analysis of Malaria in Urban Ahmedabad (Gujarat), India: Identification of Hot Spots and Risk Factors for Targeted Intervention

The world population, especially in developing countries, has experienced a rapid progression of urbanization over the last half century. Urbanization has been accompanied by a rise in cases of urban infectious diseases, such as malaria. The complexity and heterogeneity of the urban environment has made study of specific urban centers vital for urban malaria control programs, whereas more generalizable risk factor identification also remains essential. Ahmedabad city, India, is a large urban center located in the state of Gujarat, which has experienced a significant Plasmodium vivax and Plasmodium falciparum disease burden. Therefore, a targeted analysis of malaria in Ahmedabad city was undertaken to identify spatiotemporal patterns of malaria, risk factors, and methods of predicting future malaria cases. Malaria incidence in Ahmedabad city was found to be spatially heterogeneous, but temporally stable, with high spatial correlation between species. Because of this stability, a prediction method utilizing historic cases from prior years and seasons was used successfully to predict which areas of Ahmedabad city would experience the highest malaria burden and could be used to prospectively target interventions. Finally, spatial analysis showed that normalized difference vegetation index, proximity to water sources, and location within Ahmedabad city relative to the dense urban core were the best predictors of malaria incidence. Because of the heterogeneity of urban environments and urban malaria itself, the study of specific large urban centers is vital to assist in allocating resources and informing future urban planning.

Does insecticide resistance contribute to heterogeneities in malaria transmission in The Gambia?

BACKGROUND

Malaria hotspots, areas with consistently higher than average transmission, may become increasingly common as malaria declines. This phenomenon, currently observed in The Gambia, may be caused by several factors, including some related to the local vectors, whose contribution is poorly understood.

METHODS

Using WHO susceptibility bioassays, insecticide resistance status was determined in vector populations sampled from six pairs of villages across The Gambia, each pair contained a low and high prevalence village.

RESULTS

Three vector species were observed (23.5% Anopheles arabiensis, 31.2% Anopheles gambiae, 43.3% Anopheles coluzzii and 2.0% An. coluzzii × An. gambiae hybrids). Even at a fine scale, significant differences in species composition were detected within village pairs. Resistance to both DDT and deltamethrin was more common in An. gambiae, most markedly in the eastern part of The Gambia and partly attributable to differing frequencies of resistance mutations. The Vgsc-1014F target site mutation was strongly associated with both DDT (OR = 256.7, (95% CI 48.6-6374.3, p < 0.001) and deltamethrin survival (OR = 9.14, (95% CI 4.24-21.4, p < 0.001). A second target site mutation, Vgsc-1575Y, which co-occurs with Vgsc-1014F, and a metabolic marker of resistance, Gste2-114T, conferred additional survival benefits to both insecticides. DDT resistance occurred significantly more frequently in villages with high malaria prevalence (p = 0.025) though this did not apply to deltamethrin resistance.

CONCLUSION

Whilst causality of relationships requires further investigation, variation in vector species and insecticide resistance in The Gambia is associated with malaria endemicity; with a notably higher prevalence of infection and insecticide resistance in the east of the country. In areas with heterogeneous malaria transmission, the role of the vector should be investigated to guide malaria control interventions.

Malarial anaemia and anaemia severity in apparently healthy primary school children in urban and rural settings in the Mount Cameroon area: cross sectional survey

BACKGROUND

This study examines the relative importance of living in an urban versus rural setting and malaria in contributing to the public health problem of malarial anaemia (MA) and anaemia respectively in apparently healthy primary school children.

METHODS

A cross-sectional study was conducted among 727 school children aged between four and 15 years living in an urban (302) and rural (425) settings in the Mount Cameroon area. Blood sample collected from each child was used for the preparation of blood films for detection of malaria parasites and assessment of malaria parasite density as well as full blood count determination using an automated haematology analyzer. Based on haemoglobin (Hb) measurements, children with malaria parasitaemia were stratified into MA (Hb<11 g/dL); mild MA (Hb of 8-10.9 g/dL); moderate MA (Hb of 6.1-7.9 g/dL) and severe MA (Hb≤6 g/dL). Evaluation of potential determinants of MA and anaemia was performed by multinomial logistic-regression analysis and odds ratios used to evaluate risk factors.

RESULTS

Out of the 727 children examined, 72 (9.9%) had MA. The prevalence of MA and anaemia were significantly higher (χ2 = 36.5, P <0.001; χ2 = 16.19, P <0.001 respectively) in children in the urban (17.9%; 26.8% respectively) than in the rural area (4.2%; 14.8% respectively). Majority of the MA cases were mild (88.9%), with moderate (5.6%) and severe MA (5.6%) occurring in the urban area only. The age group ≤6 years was significantly (P <0.05) associated with both MA and anaemia. In addition, low parasite density was associated with MA while malaria parasite negative and microcytosis were associated with anaemia.

CONCLUSIONS

Malarial anaemia and anaemia display heterogeneity and complexity that differ with the type of settlement. The presence of severe MA and the contributions of the age group ≤6 years, low parasite density and microcytosis to the public health problem of MA and anaemia are noteworthy.

The effects of co-infection with human parvovirus B19 and Plasmodium falciparum on type and degree of anaemia in Ghanaian children

OBJECTIVE

To determin the extent to which parvovirus B19 (B19V) and co-infection of B19V and malaria contribute to risk of anaemia in children.

METHODS

B19V DNA and malaria parasites were screened for 234 children at the PML Children's Hospital in Accra. The role of B19V and co-infection with B19V and malaria in anaemia was evaluated by analysing full blood cell counts, malaria and B19V DNA results from these children.

RESULTS

The prevalence of B19V, malaria and co-infection with B19V and malaria was 4.7%, 41.9% and 2.6%, respectively. Malaria posed a greater risk in the development of mild anaemia compared to severe anaemia (OR=5.28 vrs 3.15) whereas B19V posed a higher risk in the development of severe anaemia compared to mild anaemia (OR=4.07 vrs 1.00) from a non-anaemic child. Persons with co-infection with B19V and malaria had 2.23 times the risk (95% CI=0.40-12.54) of developing severe anaemia should they already have a mild anaemia. The degree of anaemia was about three times affected by co-infection (Pillai's trace=0.551, P=0.001) as was affected by malaria alone (Pillai's trace=0.185, P=0.001). B19V alone did not significantly affect the development of anaemia in a non-anaemic child. Microcytic anaemia was associated with B19V and co-infection with B19V and malaria more than normocytic normochromic anaemia.

CONCLUSIONS

B19V was associated with malaria in cases of severe anaemia. The association posed a significant risk for exacerbation of anaemia in mild anaemic children. B19V and co-infection with B19V and malaria may be associated with microcytic anaemia rather than normocytic normochromic anaemia as seen in cases of B19V infection among persons with red cell abnormalities.

Differences in the malariometric indices of asymptomatic carriers in three communities in ibadan, Nigeria

This study was conducted to determine the malariometric indices of children in three different settings in Ibadan, Nigeria. Children were recruited from an urban slum (Oloomi) and a periurban (Sasa) and a rural community (Igbanda) in Ibadan. Children aged between 2 and 10 years were randomly selected from primary schools in the urban and periurban areas. In the rural community, children were recruited from the centre of the village. A total of 670 (55.0%) out of 1218 children recruited were positive for malaria parasitaemia. The urban population had the highest proportion of children with malaria parasitaemia. Splenomegaly was present in 31.5%, hepatomegaly in 41.5%, hepatosplenomegaly in 27.5%, and anaemia in 25.2% of the children. The parasite density was not significantly different among children in the three communities. Children in the rural community had the highest mean PCV of 34.2% and the lowest rates of splenomegaly (6.1%), hepatomegaly (7.6%), and hepatosplenomegaly (4.6%). The spleen rates, liver rates, and presence of hepatosplenomegaly and anaemia were similar in the urban and periurban communities. The malariometric indices among the asymptomatic carriers were high, especially in the urban slum. This stresses the need for intensified efforts at controlling the disease in the study area.

A randomized trial of artesunate-amodiaquine versus artemether-lumefantrine in Ghanaian paediatric sickle cell and non-sickle cell disease patients with acute uncomplicated malaria

Background

Sickle cell disease (SCD) is a genetic disorder common in malaria endemic areas. In endemic areas, malaria is a major cause of morbidity and mortality among SCD patients. This suggests the need for prompt initiation of efficacious anti-malarial therapy in SCD patients with acute malaria. However, there is no information to date, on the efficacy or safety of artemisinin combination therapy when used for malaria treatment in SCD patients.

Methods

Children with SCD and acute uncomplicated malaria (n = 60) were randomized to treatment with artesunate-amodiaquine (AA), or artemether-lumefantrine (AL). A comparison group of non-SCD children (HbAA genotype; n = 59) with uncomplicated malaria were also randomized to treatment with AA or AL. Recruited children were followed up and selected investigations were done on days 1, 2, 3, 7, 14, 28, 35, and 42. Selected clinical and laboratory parameters of the SCD patients were also compared with a group of malaria-negative SCD children (n = 82) in steady state.

Results

The parasite densities on admission were significantly lower in the SCD group, compared with the non-SCD group (p = 0.0006). The parasite reduction ratio (PRR) was lower, clearance was slower (p < 0.0001), and time for initial parasitaemia to decline by 50 and 90% were longer for the SCD group. Adequate clinical and parasitological response (ACPR) on day 28 was 98.3% (58/59) in the SCD group and 100% (57/57) in the non-SCD group. Corresponding ACPR rates on day 42 were 96.5% (55/57) in the SCD group and 96.4% (53/55) in the non-SCD group. The fractional changes in haemoglobin, platelets and white blood cell counts between baseline (day 0) and endpoint (day 42) were 16.9, 40.6 and 92.3%, respectively, for the SCD group, and, 12.3, 48.8 and 7.5%, respectively, for the non-SCD group. There were no differences in these indices between AA- and AL-treated subjects.

Conclusions

The parasite clearance of SCD children with uncomplicated malaria was slower compared with non-SCD children. AA and AL showed similar clinical and parasitological effects in the SCD and non-SCD groups. The alterations in WBC and platelet counts may have implications for SCD severity.

Trial registration

Current controlled trials ISRCTN96891086.

Pediatric anemia in rural Ghana: a cross-sectional study of prevalence and risk factors

OBJECTIVE

To assess anemia prevalence and identify associated parameters in children <3 years of age in a rural area of Ghana.

METHOD

Univariate and multivariate logistic regression of cross-sectional survey results from 861 children aged <3 years attending routine immunization services in Berekum district.

RESULTS

Anemia prevalence was 73.1%; most were either mildly (31.2%) or moderately (38.7%) affected. Risk factors for anemia (hemoglobin < 11.0 g/dl) in multivariate analysis were malaria parasitemia and male sex; these factors and younger age were associated with anemia severity. A partial defect in glucose-6-phosphate dehydrogenase was associated with decreased severity. Height-for-age, but not weight-for-age, was associated with anemia and its severity.

CONCLUSIONS

Malaria parasitemia was strongly associated with anemia and its severity, suggesting that malaria control may be the most effective way to reduce the burden of anemia in rural Ghanaian children.

Socioeconomic development as an intervention against malaria: a systematic review and meta-analysis

BACKGROUND

Future progress in tackling malaria mortality will probably be hampered by the development of resistance to drugs and insecticides and by the contraction of aid budgets. Historically, control was often achieved without malaria-specific interventions. Our aim was to assess whether socioeconomic development can contribute to malaria control.

METHODS

We did a systematic review and meta-analysis to assess whether the risk of malaria in children aged 0-15 years is associated with socioeconomic status. We searched Medline, Web of Science, Embase, the Cochrane Database of Systematic Reviews, the Campbell Library, the Centre for Reviews and Dissemination, Health Systems Evidence, and the Evidence for Policy and Practice Information and Co-ordinating Centre evidence library for studies published in English between Jan 1, 1980, and July 12, 2011, that measured socioeconomic status and parasitologically confirmed malaria or clinical malaria in children. Unadjusted and adjusted effect estimates were combined in fixed-effects and random-effects meta-analyses, with a subgroup analysis for different measures of socioeconomic status. We used funnel plots and Egger's linear regression to test for publication bias.

FINDINGS

Of 4696 studies reviewed, 20 met the criteria for inclusion in the qualitative analysis, and 15 of these reported the necessary data for inclusion in the meta-analysis. The odds of malaria infection were higher in the poorest children than in the least poor children (unadjusted odds ratio [OR] 1·66, 95% CI 1·35-2·05, p<0·001, I(2)=68%; adjusted OR 2·06, 1·42-2·97, p<0·001, I(2)=63%), an effect that was consistent across subgroups.

INTERPRETATION

Although we would not recommend discontinuation of existing malaria control efforts, we believe that increased investment in interventions to support socioeconomic development is warranted, since such interventions could prove highly effective and sustainable against malaria in the long term.

FUNDING

UK Department for International Development.

Malaria indicator surveys demonstrate a markedly lower prevalence of malaria in large cities of sub-Saharan Africa

BACKGROUND

One in eight sub-Saharan Africans now lives in a city with a population greater than 750,000. Decision makers require additional evidence regarding the burden of malaria in these large cities. This paper presents results from analysis of existing data from nationwide household surveys measuring malaria parasitaemia by microscopy among children six to 59 months of age in 15 countries of sub-Saharan Africa.

METHODS

Geo-coordinates for each survey cluster were used to determine the distance from the cluster to the centre of each of 16 large cities with populations greater than 750,000. Geo-coordinates of each site within 25 km of the centre were entered into Google Earth to obtain a satellite image of the location and determine whether it was within the boundaries of the metropolis. In the case of two countries for which survey geo-coordinates were not available, clusters located in an additional four large cities were identified based upon their designated district. Data from all sites within city boundaries were pooled together and compared to data from all rural sites within 150 km of the city centre or in the same zone of malaria endemicity.

RESULTS

Of the 20 large cities, only in Ouagadougou were more than 10% of children found to have a malaria infection. The prevalence was less than 5% for 16 of these cities. Apart from Antananarivo where both the large city and the comparison rural communities were parasite-free, the prevalence in each of the large cities was 0 to 40% of that found among children living in rural communities within 150 km of these cities or within the same zone of malaria endemicity. In 14 of the 20 large cities, all of the children living in 75% or more of the clusters were malaria parasite-free.

CONCLUSIONS

Existing data from malaria indicator surveys can be used to document the substantially lower prevalence of malaria in specific large cities. These findings will help policy makers, public health programmers and clinical workers in each country to develop and promote malaria control strategies that are suited to large cities as well as to those living in smaller communities.

An investigation of the protective effect of alpha+-thalassaemia against severe Plasmodium falciparum amongst children in Kumasi, Ghana

INTRODUCTION

Several factors influence the severity of Plasmodium falciparum; here, we investigate the impact of alpha+-thalassaemia genotype on P. falciparum parasitemia and prevalence of severe anaemia amongst microcytic children from Kumasi, Ghana.

METHODS

Seven hundred and thirty-two children (≤10 years) with P. falciparum were categorised into normocytic and microcytic (mean cell volume ≤76 fL). Microcytic individuals were genotyped for the -α(3.7) deletional thalassaemia mutation and parasite densities determined.

RESULTS

Amongst microcytic patients both parasite densities and prevalence of severe malaria parasitemia (≥100 000/μL) were significantly lower (P < 0.001) in the presence of an alpha+-thalassaemia genotype compared with non-alpha+-thalassaemia genotype. There was no evidence that alpha+-thalassaemia protected against severe anaemia. The protection conferred by alpha-thalassaemia genotype against severe P. falciparum parasitemia did not change with increasing age.

CONCLUSION

The severity of P. falciparum parasitemia was significantly lower in both the homozygous and heterozygous alpha+-thalassaemia groups compared with microcytic individuals with non-alpha+-thalassaemia genotype. The protective effect, from severe malaria, of the alpha+-thalassaemia allele does not alter with age.

Malariometric Indices among Nigerian Children in a Rural Setting

Malaria contributes to high childhood morbidity and mortality in Nigeria. To determine its endemicity in a rural farming community in the south-south of Nigeria, the following malariometric indices, namely, malaria parasitaemia, spleen rates, and anaemia were evaluated in children aged 2-10 years. This was a descriptive cross-sectional survey among school-age children residing in a rubber plantation settlement. The children were selected from six primary schools using a multistaged stratified cluster sampling technique. They were all examined for pallor, enlarged spleen, or liver among other clinical parameters and had blood films for malaria parasites. Of the 461 children recruited, 329 (71.4%) had malaria parasites. The prevalence of malaria parasitaemia was slightly higher in the under fives than that of those ≥5 years, 76.2% and 70.3%, respectively. Splenic enlargement was present in 133 children (28.9%). The overall prevalence of anaemia was 35.7%. Anaemia was more common in the under-fives (48.8%) than in those ≥5 years (32.8%). The odds of anaemia in the under fives were significantly higher than the odds of those ≥5 years (OR = 1.95 [1.19-3.18]). Malaria is highly endemic in this farming community and calls for intensification of control interventions in the area with special attention to school-age children.

High mosquito burden and malaria transmission in a district of the city of Douala, Cameroon

Background

Rapid demographic growth in Douala city, Cameroon, has resulted in profound ecological and environmental changes. Although demographic changes can affect anopheline mosquito breeding sites, there is a lack of understanding about the epidemiological impact that such changes might have on vector ecology and malaria transmission.

Methods

A 12-month entomological study was conducted in a highly populated district of Douala called Ndogpassi. Adult mosquitoes were collected using two methods: 1) human landing catches (HLC); and 2) Centers for Disease Control and Prevention (CDC) light traps; these methods were used twice monthly from January to December 2011. Mosquito genus and species were identified with morphological and molecular diagnostic tools. The sampling efficiency of the CDC light trap and HLC were compared. Anopheles gambiae infection with Plasmodium falciparum was detected using ELISA. Susceptibility to DDT, permethrin, and deltamethrin insecticides were also determined.

Results

A total of 6923 mosquitoes were collected by HLC (5198) and CDC light traps (1725). There was no equivalence in the sampling efficiency between light traps and human landing catches (P > 0.01). With 51% of the total, Culex was the most common, followed by Anopheles (26.14%), Mansonia (22.7%) and Aedes (0.1%). An. gambiae ss (M form) comprised ~98% of the total anophelines collected. An. gambiae had a biting rate of 0.25 to 49.25 bites per human per night, and was the only species found to be infected with P. falciparum. A P. falciparum infection rate of 0.5% was calculated (based on enzyme-linked immunosorbent assays using the circumsporozoite surface protein). The entomological inoculation rate was estimated at 31 infective bites per annum. Insecticide susceptibility tests on An. gambiae females revealed a mortality rate of 33%, 76% and 98% for DDT, permethrin and deltamethrin, respectively. The West African kdr allele (L1014F) was detected in 38 of the 61 An. gambiae analyzed (62.3%).

Conclusions

The present study revealed seasonal malaria transmission in Douala. High levels of An. gambiae were detected along with a high prevalence of insecticide resistance in this vector population. These findings highlight the need to promote use of insecticide-impregnated bed nets in Douala.

Urbanization and Infectious Diseases: General Principles, Historical Perspectives, and Contemporary Challenges

In 2009, a major demographic line was crossed: for the first time in history, the majority of the world population lived in cities rather than in towns and countryside (Fig. 4.1). This shift has been occurring over the past 100 years, with the most rapid rate of urban growth occurring over in the latter half of the twentieth century. Urban centers in the more developed regions of the world (i.e., North America, Australia, New Zealand, and Europe) experienced earlier growth in the 1920s–1950s, and since then, the rapid rate of urban growth has been concentrated in the cities and towns of developing nations [1].

Malaria transmission in Libreville: results of a one year survey

Background

In Gabon, vector transmission has been poorly studied. Since the implementation of the Roll Back malaria recommendations, clinical studies have shown a decline in the burden of malaria in Libreville, the capital city of Gabon. To better understand the transmission dynamic in Libreville, an entomological survey was conducted in five districts of the city.

Methods

Mosquitoes were sampled by human landing collection during 1 year in five districts of Libreville: Alibandeng, Beauséjour, Camp des Boys and Sotega. Mosquitoes were identified morphologically and by molecular methods. The Plasmodium falciparum circumsporozoïte indices were measured by ELISA, and the entomological inoculation rates (EIR) were calculated for all areas. Molecular assessments of pyrethroid knock down resistance (kdr) and of insensitive acetylcholinesterase resistance were conducted.

Results

A total of 57,531 mosquitoes were caught during 341 person-nights (161 person-nights indoor and 180 person-nights outdoor) among which, 4,223 were Anopheles gambiae s.l. The average Human Biting Rate fell from 15.5 bites per person during the rainy season to 4.7 during the dry season. The An. gambiae complex population was composed of An. gambiae s.s molecular form S (99.5%), Anopheles melas (0.3%) and An. gambiae s.s. form M (0.2%). Thirty-three out of 4,223 An. gambiae s.l. were found to be infected by P. falciparum (CSP index = 0.78%). The annual EIR was estimated at 33.9 infected bites per person per year ranging from 13 in Alibandeng to 88 in Sotega. No insensitive AChE mutation was identified but both kdr-w and kdr-e mutations were present in An. gambiae molecular form S with a higher frequency of the kdr-w allele (76%) than the kdr-e allele (23.5%).

Conclusion

Malaria transmission in Libreville occurred mainly during the rainy season but also during the dry season in the five districts. Transmission level is high and seems to be very heterogeneous in the town. Interestingly, the highest EIR was recorded in the most central and urbanized quarter and the lowest in a peripheral area. The decrease of transmission usually seen from peri-urban areas to urban centers is probably more dependent of the socio-economic level of a quarter than of its location in the city. Urban malaria control programmes need to consider the socio economic level of an area rather than the location in the city in order to determine the areas most favourable to malaria transmission.

Feasibility of home management using ACT for childhood malaria episodes in an urban setting

BACKGROUND

Over 90% of malaria cases occur in Sub-Saharan Africa, where a child under the age of 5 years dies from this illness every 30 seconds. The majority of families in Sub- Saharan Africa treat malaria at home, but therapy is often incomplete, hence the World Health Organization has adopted the strategy of home management of malaria to solve the problem. The purpose of this study was to determine community perception and the treatment response to episodes of childhood malaria in an urban setting prior to implementation of home management using artemisinin-based combination therapy (ACT).

METHODS

This qualitative exploratory study on the home management of malaria in urban children under 5 years of age used 15 focus group discussions and 20 in-depth interviews in various categories of caregivers of children under 5 years. One hundred and eighteen people participated in the focus group discussions and 20 in the in-depth interviews. The study explored beliefs and knowledge about malaria, mothers' perception of home management of the disease, health-seeking behavior, prepackaged treatment of malaria using ACT and a rapid diagnostic test, preferred channels for home management of uncomplicated malaria, communication, the role of the community in home management of malaria, and the motivation of drug distributors in the community.

RESULTS

The mothers' perception of malaria was the outcome of events other than mosquito bites. Home treatment is very common and is guided by the way mothers perceive signs and symptoms of malaria. Frequent change of malarial drugs by the national health policy and financial difficulties were the main problems mothers faced in treating febrile children. Rapid diagnostic testing and prepackaged ACT for simple malaria in children under 5 years would be accepted if it was offered at an affordable price. Tribalism and religious beliefs might hinder the delivery of home management of malaria. The availability of rapid diagnostic testing and ACT all year round is one of the challenges of home management of malaria. Although radio and television featured among the current sources of information within the community, meetings, churches, schools, and other public gatherings were the best venues for social mobilization, while community health workers and community leaders were the best sensitization agents for positive behavior change to adhere to home management of malaria. Monetary incentives should be offered to community drug distributors. This should be deducted from the combined price of ACT and rapid diagnostic testing.

CONCLUSION

For successful implementation of home management of malaria, there should be proper education, social mobilization of the population, and continuous monitoring and evaluation of field activities to ensure adequate stocks of ACT and rapid diagnostic testing within the framework of the intervention.

Socioeconomic inequities in the health and nutrition of children in low/middle income countries

OBJECTIVE

To describe the effects of social inequities on the health and nutrition of children in low and middle income countries.

METHODS

We reviewed existing data on socioeconomic disparities within-countries relative to the use of services, nutritional status, morbidity, and mortality. A conceptual framework including five major hierarchical categories affecting inequities was adopted: socioeconomic context and position, differential exposure, differential vulnerability, differential health outcomes, and differential consequences. The search of the PubMed database since 1990 identified 244 articles related to the theme. Results were also analyzed from almost 100 recent national surveys, including Demographic Health Surveys and the UNICEF Multiple Indicator Cluster Surveys.

RESULTS

Children from poor families are more likely, relative to those from better-off families, to be exposed to pathogenic agents; once they are exposed, they are more likely to become ill because of their lower resistance and lower coverage with preventive interventions. Once they become ill, they are less likely to have access to health services and the quality of these services is likely to be lower, with less access to life-saving treatments. As a consequence, children from poor family have higher mortality rates and are more likely to be undernourished.

CONCLUSIONS

Except for child obesity and inadequate breastfeeding practices, all the other adverse conditions analyzed were more prevalent in children from less well-off families. Careful documentation of the multiple levels of determination of socioeconomic inequities in child health is essential for understanding the nature of this problem and for establishing interventions that can reduce these differences.

Cohort trial reveals community impact of insecticide-treated nets on malariometric indices in urban Ghana

The efficacy of insecticide-treated nets (ITNs) in prevention of malaria and anaemia has been shown in rural settings, but their impact in urban settings is unknown. We carried out an ITN intervention in two communities in urban Accra, Ghana, where local malaria transmission is known to occur. There was evidence for a mass or community effect, despite ITN use by fewer than 35% of households. Children living within 300 m of a household with an ITN had higher haemoglobin concentrations (0.5g/dl higher, P=0.011) and less anaemia (odds ratio 2.21, 95% CI 1.08-4.52, P=0.031 at month 6), than children living more than 300 m away from a household with an ITN, although malaria parasitaemias were similar. With urban populations growing rapidly across Africa, this study shows that ITNs will be an effective tool to assist African countries to achieve their Millennium Development Goals in urban settings. [Registered trial number ISRCTN42261314; http://www.controlled-trials.com/ISRCTN42261314].

Significance of travel to rural areas as a risk factor for malarial anemia in an urban setting

The epidemiology of malaria in urban environments is poorly characterized, yet increasingly problematic. We conducted an unmatched case-control study of risk factors for malarial anemia with high parasitemia in urban Kisumu, Kenya, from June 2002 through February 2003. Cases (n = 80) were hospital patients with a hemoglobin level < or = 8 g/dL and a Plasmodium parasite density > or = 10,000/microL. Controls (n = 826) were healthy respondents to a concurrent citywide knowledge, attitude, and practice survey. Children who reported spending at least one night per month in a rural area were especially at risk (35% of cases; odds ratio = 9.3, 95% confidence interval [CI] = 4.4-19.7, P < 0.0001), and use of mosquito coils, bed net ownership, and house construction were non-significant, potentially indicating that malaria exposure during rural travel comprises an important element of risk. Control of severe malaria in an urban setting may be complicated by Plasmodium infections acquired elsewhere. Epidemiologic studies of urban malaria in low transmission settings should take travel history into account.

Malaria is associated with poor school performance in an endemic area of the Brazilian Amazon

Background

Approximately 40% of the world's population is at risk for malaria. In highly endemic tropical areas, malaria is a major cause of morbidity and mortality during infancy. There is a complex interrelationship between malaria, malnutrition and intestinal helminths, and this may impair cognitive development in children. The aim of this study was to determine the relationship between malaria and school performance in children living in an endemic area where Plasmodium vivax is the species responsible for most of the cases.

Methods

The study was conducted in the Municipality of Careiro, Amazonas, Brazil, with five to14 year-old children, studying the first eight grades of public school, during the year 2008. After an initial active case detection, during nine months of follow-up, passive malaria cases detection was instituted, through a thick blood smear performed in every child with fever. School performance was evaluated by the final notes in Mathematics and Portuguese Language. Performance was considered poor when either of the final notes in these disciplines was below the 50^th percentile for the respective class and grade.

Results

The total number of students followed-up in the cohort was 198. Malarial attacks were reported in 70 (35.4%) of these students, with no cases of severe disease. Plasmodium vivax was detected in 69.2% of the attacks, Plasmodium falciparum in 25.5% and both species in 5.3%. In the multivariate analysis, adjusting for age, mother's education, time living in the study area and school absenteeism, presenting with at least one episode of malaria independently predicted a poor performance at school [OR = 1.91 (1.04-3.54); p = 0.039].

Conclusion

Non-severe malaria compromises the school performance of children even during a nine-month follow-up, potentially contributing to the maintenance of underdevelopment in countries endemic for malaria. This is the first evidence of such impact in Latin America, where P. vivax is responsible for the majority of the cases.

Impact of Plasmodium falciparum infection on the frequency of moderate to severe anaemia in children below 10 years of age in Gabon

Background

Improving the understanding of childhood malarial anaemia may help in the design of appropriate management strategies.

Methods

A prospective observational study over a two-year period to assess the burden of anaemia and its relationship to Plasmodium falciparum infection and age was conducted in 8,195 febrile Gabonese children.

Results

The proportion of children with anaemia was 83.6% (n = 6830), higher in children between the ages of six and 23 months. Those under three years old were more likely to develop moderate to severe anaemia (68%). The prevalence of malaria was 42.7% and P. falciparum infection was more frequent in children aged 36–47 months (54.5%). The proportion of anaemic children increased with parasite density (p < 0.01). Most of infected children were moderately to severely anaemic (69.5%, p < 0.01). Infants aged from one to 11 months had a higher risk of developing severe malarial anaemia. In children over six years of age, anaemia occurrence was high (>60%), but was unrelated to P. falciparum parasitaemia.

Conclusion

Malaria is one of the main risk factors for childhood anaemia which represents a public health problem in Gabon. The risk of severe malarial anaemia increases up the age of three years. Efforts to improve strategies for controlling anaemia and malaria are needed.

Social and environmental malaria risk factors in urban areas of Ouagadougou, Burkina Faso

BACKGROUND

Despite low endemicity, malaria remains a major health problem in urban areas where a high proportion of fevers are presumptively treated using anti-malarial drugs. Low acquired malaria immunity, behaviour of city-dwellers, access to health care and preventive interventions, and heterogenic suitability of urban ecosystems for malaria transmission contribute to the complexity of the malaria epidemiology in urban areas.

METHODS

The study was designed to identify the determinants of malaria transmission estimated by the prevalence of anti-circumsporozoite (CSP) antibodies, the prevalence and density of Plasmodium falciparum infection, and the prevalence of malarial disease in areas of Ouagadougou, Burkina-Faso. Thick blood smears, dried blood spots and clinical status have been collected from 3,354 randomly chosen children aged 6 months to 12 years using two cross-sectional surveys (during the dry and rainy seasons) in eight areas from four ecological strata defined according to building density and land tenure (regular versus irregular). Demographic characteristics, socio-economic information, and sanitary and environmental data concerning the children or their households were simultaneously collected. Dependent variables were analysed using mixed multivariable models with random effects, taking into account the clustering of participants within compounds and areas.

RESULTS

Overall prevalences of CSP-antibodies and P. falciparum infections were 7.7% and 16.6% during the dry season, and 12.4% and 26.1% during the rainy season, respectively, with significant differences according to ecological strata. Malaria risk was significantly higher among children who i) lived in households with lower economic or education levels, iii) near the hydrographic network, iv) in sparsely built-up areas, v) in irregularly built areas, vi) who did not use a bed net, vii) were sampled during the rainy season or ii) had traveled outside of Ouagadougou.

CONCLUSION

Malaria control should be focused in areas which are irregularly or sparsely built-up or near the hydrographic network. Furthermore, urban children would benefit from preventive interventions (e.g. anti-vectorial devices or chemoprophylaxis) aimed at reducing malaria risk during and after travel in rural areas.

Pattern of drug utilization for treatment of uncomplicated malaria in urban Ghana following national treatment policy change to artemisinin-combination therapy

BACKGROUND

Change of first-line treatment of uncomplicated malaria to artemisinin-combination therapy (ACT) is widespread in Africa. To expand knowledge of safety profiles of ACT, pharmacovigilance activities are included in the implementation process of therapy changes. Ghana implemented first-line therapy of artesunate-amodiaquine in 2005. Drug utilization data is an important component of determining drug safety, and this paper describes how anti-malarials were prescribed within a prospective pharmacovigilance study in Ghana following anti-malarial treatment policy change.

METHODS

Patients with diagnosis of uncomplicated malaria were recruited from pharmacies of health facilities throughout Accra in a cohort-event monitoring study. The main drug utilization outcomes were the relation of patient age, gender, type of facility attended, mode of diagnosis and concomitant treatments to the anti-malarial regimen prescribed. Logistic regression was used to predict prescription of nationally recommended first-line therapy and concomitant prescription of antibiotics.

RESULTS

The cohort comprised 2,831 patients. Curative regimens containing an artemisinin derivative were given to 90.8% (n = 2,574) of patients, although 33% (n = 936) of patients received an artemisinin-based monotherapy. Predictors of first-line therapy were laboratory-confirmed diagnosis, age >5 years, and attending a government facility. Analgesics and antibiotics were the most commonly prescribed concomitant medications, with a median of two co-prescriptions per patient (range 1-9). Patients above 12 years were significantly less likely to have antibiotics co-prescribed than patients under five years; those prescribed non-artemisinin monotherapies were more likely to receive antibiotics. A dihydroartemisinin-amodiaquine combination was the most used therapy for children under five years of age (29.0%, n = 177).

CONCLUSION

This study shows that though first-line therapy recommendations may change, clinical practice may still be affected by factors other than the decision or ability to diagnose malaria. Age, diagnostic confirmation and suspected concurrent conditions lead to benefit:risk assessments for individual patients by clinicians as to which anti-malarial treatment to prescribe. This has implications for adherence to policy changes aiming to implement effective use of ACT. These results should inform education of health professionals and rational drug use policies to reduce poly-pharmacy, and also suggest a potential positive impact of increased access to testing for malaria both within health facilities and in homes.

Impact of urban agriculture on malaria vectors in Accra, Ghana

To investigate the impact of urban agriculture on malaria transmission risk in urban Accra larval and adult stage mosquito surveys, were performed. Local transmission was implicated as Anopheles spp. were found breeding and infected Anopheles mosquitoes were found resting in houses in the study sites. The predominant Anopheles species was Anopheles gambiae s.s.. The relative proportion of molecular forms within a subset of specimens was 86% S-form and 14% M-form. Anopheles spp. and Culex quinquefasciatus outdoor biting rates were respectively three and four times higher in areas around agricultural sites (UA) than in areas far from agriculture (U). The annual Entomological Inoculation Rate (EIR), the number of infectious bites received per individual per year, was 19.2 and 6.6 in UA and U sites, respectively. Breeding sites were highly transitory in nature, which poses a challenge for larval control in this setting. The data also suggest that the epidemiological importance of urban agricultural areas may be the provision of resting sites for adults rather than an increased number of larval habitats. Host-seeking activity peaked between 2–3 am, indicating that insecticide-treated bednets should be an effective control method.

Safety monitoring of a new pentavalent vaccine in the expanded programme on immunisation in Ghana

BACKGROUND AND OBJECTIVE

Safety monitoring of vaccines used in expanded programmes on immunisation is important in all countries, including those with limited resources. As the rates of target diseases decrease, parents become less accepting of even minor common adverse events. Identification, detection, prevention and appropriate communication of adverse events following immunisation (AEFI) are therefore essential to preserve the integrity of immunisation programmes and protect public health. The objective of this study was to document the occurrence of common minor AEFI associated with a newly introduced pentavalent vaccine for routine immunisation in Ghana's expanded programme on immunisation.

METHODS

A prospective descriptive study on AEFI associated with the administration of a pentavalent diphtheria, tetanus, pertussis, hepatitis B and Haemophilus influenzae type B (DTP-hepatitis B vaccine/Hib vaccine) vaccine that is part of the Expanded Programme on Immunisation was carried out in four locations in Accra, Ghana. These locations were the nation's premier teaching hospital (the Korle-Bu Teaching Hospital) two urban polyclinics (the Mamprobi and Ussher Town polyclinics) and a community immunisation centre (the Zongo Junction Immunisation Centre).A total of 406 infants were recruited for the study. Upon receipt of signed informed consent from the parents/guardians of the infants, the parents/guardians were supplied with a pink card that functioned as a pseudo-diary for recording AEFI that occurred at home and for measuring and noting the sizes of any injection-site swellings that might occur. It also enabled each participant to obtain free medical care at the Department of Child Health, Korle-Bu Teaching Hospital for the duration of the study (from September 2003 to December 2004) and until the child was 12 months old. Information about the occurrence of AEFI was actively solicited during each visit for immunisation and also at a visit 4 weeks after administration of the last dose of pentavalent vaccine, when participants were asked to report to the respective immunisation centres for the specific purpose of reporting any AEFI which might have occurred in the intervening period. These AEFI were analysed separately from those reported to the dedicated hospital unit at the Department of Child Health, Korle-Bu Teaching Hospital, since the AEFI reported to that unit were all verified and recorded by trained physicians.

RESULTS

Of the 406 infants, 368 completed the study, whereas 38 defaulted or were lost to follow-up. There were 104 attendances to report cases of suspected AEFI requiring physician attention at the Department of Child Health, Korle-Bu Teaching Hospital. These attendances were made by 74 patients who reported 190 events; notable among these were cough (26.3% of all AEFI reported to the hospital), fever (17.4%), common cold (12.1%), vomiting (7.4%) and diarrhoea (6.8%). Three of these visits involved AEFI that were classified as 'serious', since they required hospitalisation, but all three were considered to be unlikely to be related to vaccine administration. In addition, actively solicited information on AEFI following immunisation from 921 individual interviews with the parents/guardians of immunised infants during the follow-up visits resulted in reports of 259 events being reported, the most common, according to crude incidence rates, being fever (14.7%), common cold (3.8%), crying (3%) and cough (2.8%).

CONCLUSION

The results of this study show agreement with safety studies on vaccines containing identical or similar antigens performed elsewhere and indicate the safety and tolerability of the pentavalent DTP-hepatitis B vaccine/Hib vaccine in Ghanaian children.

Anaemia: a useful indicator of neglected disease burden and control

The authors argue that one way of evaluating the effectiveness of an intervention aimed at controlling neglected tropical diseases would be to assess its impact on anemia prevalence.

Seroprevalence of malaria in inhabitants of the urban zone of Antananarivo, Madagascar

Background

Antananarivo, the capital of Madagascar, is located at an altitude of over 1,200 m. The environment at this altitude is not particularly favourable to malaria transmission, but malaria nonetheless remains a major public health problem. The aim of this study was to evaluate exposure to malaria in the urban population of Antananarivo, by measuring the specific seroprevalence of Plasmodium falciparum.

Methods

Serological studies specific for P. falciparum were carried out with an indirect fluorescent antibody test (IFAT). In a representative population of Antananarivo, 1,059 healthy volunteers were interviewed and serum samples were taken.

Results

The seroprevalence of IgG+IgA+IgM was 56.1% and that of IgM was 5.9%. The major risk factor associated with a positive IgG+IgA+IgM IFAT was travel outside Antananarivo, whether in the central highlands or on the coast. The abundance of rice fields in certain urban districts was not associated with a higher seroprevalence.

Conclusion

Malaria transmission levels are low in Antananarivo, but seroprevalence is high. Humans come into contact with the parasite primarily when travelling outside the city. Further studies are required to identify indigenous risk factors and intra-city variations more clearly.

Malaria and anaemia among children in two communities of Kumasi, Ghana: a cross-sectional survey

BACKGROUND

A survey in Kumasi, Ghana found a marked Plasmodium falciparum prevalence difference between two neighbouring communities (Moshie Zongo and Manhyia). The primary objective of this follow-up study was to determine whether this parasite rate difference was consistent over time. Secondary objectives were to compare prevalences of clinical malaria, anaemia, intestinal parasite infections, and malnutrition between these communities; and to identify potential risk factors for P. falciparum infection and anaemia.

METHODS

A cross-sectional house-to-house survey of P. falciparum parasitaemia, clinical malaria, anaemia, anthropometric indices, and intestinal helminths was conducted in April-May 2005. Data collection included child and household demographics, mosquito avoidance practices, distance to nearest health facility, child's travel history, symptoms, and anti-malarial use. Risk factors for P. falciparum and anaemia (Hb < 11 g/dl) were identified using generalized linear mixed models.

RESULTS

In total, 296 children were tested from 184 households. Prevalences of P. falciparum, clinical malaria, anaemia, and stunting were significantly higher in Moshie Zongo (37.8%, 16.9%, 66.2% and 21.1%, respectively) compared to Manhyia (12.8%, 3.4%, 34.5% and 7.4%). Of 197 children tested for helminths, four were positive for Dicrocoelium dendriticum. Population attributable risks (PAR%) of anaemia were 16.5% (P. falciparum) and 7.6% (malnutrition). Risk factors for P. falciparum infection were older age, rural travel, and lower socioeconomic status. Risk factors for anaemia were P. falciparum infection, Moshie Zongo residence, male sex, and younger age.

CONCLUSION

Heterogeneities in malariometric indices between neighbouring Kumasi communities are consistent over time. The low helminth prevalence, and the twofold higher PAR% of anaemia attributable to P. falciparum infection compared to malnutrition, indicate the importance of malaria as a cause of anaemia in this urban population.