Comment évaluer la morbidité attribuable au paludisme en zone d’endémie ?

Co-circulation of Plasmodium and Bacterial DNAs in Blood of Febrile and Afebrile Children from Urban and Rural Areas in Gabon

Malaria is considered to be the most common etiology of fever in sub-Saharan Africa while bacteremias exist but are under assessed. This study aimed to assess bacteremias and malaria in children from urban and rural areas in Gabon. DNA extracts from blood samples of 410 febrile and 60 afebrile children were analyzed using quantitative polymerase chain reaction. Plasmodium spp. was the microorganism most frequently detected in febrile (78.8%, 323/410) and afebrile (13.3%, 8/60) children, (P < 0.001). DNA from one or several bacteria were detected in 15 febrile patients (3.7%) but not in the controls (P = 0.1). This DNA was more frequently detected as co-infections among febrile children tested positive for Plasmodium (4.6%, 15/323) than in those tested negative for Plasmodium (0%, 0/87; P = 0.04). The bacteria detected were Streptococcus pneumoniae 2.4% (10/410), Staphylococcus aureus 1.7% (7/410), Salmonella spp. 0.7% (3/410), Streptococcus pyogenes 0.2% (1/410) and Tropheryma whipplei 0.2% (1/410) only in febrile children. Coxiella burnetii, Borrelia spp., Bartonella spp., Leptospira spp., and Mycobacterium tuberculosis were not observed. This paper reports the first detection of bacteremia related to T. whipplei in Gabon and shows that malaria decreases in urban areas but not in rural areas. Co-infections in febrile patients are common, highlighting the need to improve fever management strategies in Gabon.

Pattern of the Antimalarials Prescription during Pregnancy in Bangui, Central African Republic

Introduction. The aim of this study was to identify the antimalarials prescribed during the pregnancy and to document their timing. Method. From June to September 2009, a survey was conducted on 565 women who gave birth in the Castors maternity in Bangui. The antenatal clinics cards were checked in order to record the types of antimalarials prescribed during pregnancy according to gestational age. Results. A proportion of 28.8% ANC cards contained at least one antimalarial prescription. The commonest categories of antimalarials prescribed were: quinine (56.7%), artemisinin-based combinations (26.8%) and artemisinin monotherapy (14.4%). Among the prescriptions that occurred in the first trimester of pregnancy, artemisinin-based combinations and artemisinin monotherapies represented the proportions of (10.9%) and (13.3%). respectively. Conclusion. This study showed a relatively high rate (>80%) of the recommended antimalarials prescription regarding categories of indicated antimalarials from national guidelines. But, there is a concern about the prescription of the artemisinin derivatives in the first trimester of pregnancy, and the prescription of artemisinin monotherapy. Thus, the reinforcement of awareness activities of health care providers on the national malaria treatment during pregnancy is suggested.

[Change of protocol in the verbal autopsy method and measure of malaria mortality in rural areas in Senegal]

In rural Senegal, three populations have been followed up since several decades and the malaria mortality trend has been observed since the mid-1980s. However, limits are associated with the verbal autopsy method used to determine causes of death, especially deaths due to malaria. A change in protocol occurred in recent years in two of these three sites with the involvement of two physicians (instead of only one) in the diagnosis. The objective is here to measure its potential impact on diagnosis of malaria deaths. Five hundred and fifteen diagnoses reported on child deaths occurred from 2000 to 2005 have been analysed. We have identified, on the basis of a multinomial logistic regression model, factors affecting the determination of malaria deaths among the characteristics of the child, the death, the illness and its symptoms, and we also took into account method factors. Factors related to the method do not play on the malaria diagnosis. This result insures the continuity of the series on malaria mortality statistics since 2000 in the two sites despite changes in the method. However, the new protocol leads to vanish possibility of having deaths among ill-defined or unknown causes. In the African context of absence of health statistics, data obtained through the verbal autopsy method in demographic surveillance system can provide accurate information in the epidemiological field, even regarding malaria.

[Malaria in health centres in the southern districts of Brazzaville, Congo]

During the surveys on antimalarial drug efficacy carried out from 2003 to 2006, we systematically checked the presence of Plasmodium falciparum in patients consulting in two health centres located in the south of Brazzaville. The first centre is situated in the urban zone; the second, in the semi rural area. The objective of this survey was to determine the prevalence of malaria-infected patients among the consulting patients and the prevalence of symptomatic patients with acute malaria attacks based on the parasitic density. Patients with parasites were assigned to one of the 5 following classifications: <2000, > or =2000, <5000, > or =5000 and > or =10,000 asexual parasites/microl of blood. Based on the threshold of parasite density 10,000 asexual parasites/microl, 10% and 24% of febrile patients in Tenrikyo and Madibou health centres were diagnosed as cases of malaria, respectively; 13.6% and 26.8% of patients under 5 years old consulting in these two health centres had malaria attacks. If the threshold of parasite density is lowered to 2000 asexual parasites/microl for patients > or =15 years old, 8% and 14% of adults in Tenrikyo and Madibou had malaria attacks, respectively The malaria burden was higher in the periphery of the city of Brazzaville than in the urbanized central districts. The Madibou health centre located in semi rural zone receives twice as many malaria cases for consultation than Tenrikyo located in the urban zone.

Usefulness of clinical algorithm as screening process to detected malaria in low-to-moderate transmission areas of scarce health related resources

INTRODUCTION

In areas of low-to-moderate risk of malaria transmission, the World Health Organization recommends parasitic confirmation before treatment. Such areas have usually low budget for health care and malaria diagnosis is mostly based on clinical assumption. Algorithms have been developed to improve health care providers' identification of clinical malaria and could be used as screening to reduce the number of individuals requiring parasitic confirmation before treating.

METHODS

Prospective clinical and parasitological data were collected from inhabitants of four villages from March 1984 through March 1985. Symptoms and signs recorded by physicians were used in multivariate models to test the best predictors of malaria. Sensitivity and specificity were calculated for various cut-offs of scores and compared to clinical diagnosis.

RESULTS

A total of 8.941 individuals were evaluated during the 1-year period of data collection. The overall prevalence of malaria parasitemia was 19.7% (n=1762). Of the 4280 people evaluated during the high season period, 24% (n=1024) presented any parasitemia, 55.3% (566/1024) due to Plasmodium falciparum. The final clinical algorithm included history of fever, rigors, headache, absence of myalgia, backache or cough, nausea or vomiting, and splenomegaly on examination as predictable variables. At a cut-off score of 2.0, the sensitivity of the algorithm was higher for the entire sample (57% vs. 43%), for high season period (70% vs. 53%), for children less than 6 years of age (59% vs. 40%), for individuals with parasitemia due to P. falciparum (65% vs. 48%), and for high P. falciparum parasitemic individuals at high season (84% vs. 68%). However, specificity was usually lower unless a higher cut off was used, in which case the gain in sensitivity by using the algorithm was reduced.

CONCLUSION

In low-to-moderate transmission areas in which health related resources are scarce, a clinical algorithm increases the identification of real cases of malaria and could be used as screening for further parasitic identification.

Utilization of monoclonal antibodies for detection of Plasmodium falciparum antigen in cerebrospinal fluid of cerebral malaria patients

A uniform protein profile of bands at 34, 43, and 52 kDa was obtained with all the cerebrospinal fluid (CSF) samples of malaria (10 in number) and non-malaria patients (31 in number) by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). An immunoreactive band was observed at 43 kDa in CSF samples of cerebral malaria patients but not in non-malaria cases when tested with rabbit anti-Plasmodium falciparum antibodies by Western blot analysis. Eleven reactive monoclonal antibodies against P. falciparum were stabilized and expanded. Nine monoclonal antibodies were reactive to CSF samples of cerebral malaria and non-malaria and P. falciparum antigen by dot-ELISA and a common immunoreactive band at 43 kDa by Western blot. One clone Cl-2 was reactive at 43 kDa with CSF of the cerebral malaria patients and also in P. falciparum antigen but at 66 kDa with non-malarial CSF samples in Western blot. The other two clones (Cl-6 and 14) reacted with 3/31 (90% specific) and 8/31 (74%) CSF samples of non-malaria patients, respectively. The monoclonal antibody based ELISA reported in the present study using clone-6 can therefore offer another possibility for developing rapid, easy-to-perform, low-cost tests for diagnosis of cerebral malaria in CSF samples. Western blot using clone-2 might be useful for the detection of cerebral malaria antigen in CSF.

Estimates of the burden of malaria morbidity in Africa in children under the age of 5 years

OBJECTIVE

To estimate the direct burden of malaria among children younger than 5 years in sub-Saharan Africa (SSA) for the year 2000, as part of a wider initiative on burden estimates.

METHODS

A systematic literature review was undertaken in June 2003. Severe malaria outcomes (cerebral malaria, severe malarial anaemia and respiratory distress) and non-severe malaria data were abstracted separately, together with information on the characteristics of each study and its population. Population characteristics were also collated at a national level. A meta-regression model was used to predict the incidence of malaria fevers at a national level. For severe outcomes, results were presented as median rates as data were too sparse for modelling.

RESULTS

For the year 2000, an estimated 545,000 (uncertainty interval: 105,000-1,750,000) children under the age of 5 in SSA experienced an episode of severe malaria for which they were admitted to hospital. A total of 24,000 (interquartile range: 12,000-37,000) suffered from persistent neurological deficits as a result of cerebral malaria. The number of malaria fevers associated with high parasite density in under-5s in SSA in 2000 was estimated as 115,750,000 (uncertainty interval: 91,243,000-257,957,000).

CONCLUSION

Our study predicts a lower burden than previous estimates of under-5 malaria morbidity in SSA. As there is a lack of suitable data to enable comprehensive estimates of annual malaria incidence, we describe the information needed to improve the validity of future estimates.

Space-time clustering of childhood malaria at the household level: a dynamic cohort in a Mali village

BACKGROUND

Spatial and temporal heterogeneities in the risk of malaria have led the WHO to recommend fine-scale stratification of the epidemiological situation, making it possible to set up actions and clinical or basic researches targeting high-risk zones. Before initiating such studies it is necessary to define local patterns of malaria transmission and infection (in time and in space) in order to facilitate selection of the appropriate study population and the intervention allocation. The aim of this study was to identify, spatially and temporally, high-risk zones of malaria, at the household level (resolution of 1 to 3 m).

METHODS

This study took place in a Malian village with hyperendemic seasonal transmission as part of Mali-Tulane Tropical Medicine Research Center (NIAID/NIH). The study design was a dynamic cohort (22 surveys, from June 1996 to June 2001) on about 1300 children (<12 years) distributed between 173 households localized by GPS. We used the computed parasitological data to analyzed levels of Plasmodium falciparum, P. malariae and P. ovale infection and P. falciparum gametocyte carriage by means of time series and Kulldorff's scan statistic for space-time cluster detection.

RESULTS

The time series analysis determined that malaria parasitemia (primarily P. falciparum) was persistently present throughout the population with the expected seasonal variability pattern and a downward temporal trend. We identified six high-risk clusters of P. falciparum infection, some of which persisted despite an overall tendency towards a decrease in risk. The first high-risk cluster of P. falciparum infection (rate ratio = 14.161) was detected from September 1996 to October 1996, in the north of the village.

CONCLUSION

This study showed that, although infection proportions tended to decrease, high-risk zones persisted in the village particularly near temporal backwaters. Analysis of this heterogeneity at the household scale by GIS methods lead to target preventive actions more accurately on the high-risk zones identified. This mapping of malaria risk makes it possible to orient control programs, treating the high-risk zones identified as a matter of priority, and to improve the planning of intervention trials or research studies on malaria.