Comparison of PCR-based detection of Plasmodium falciparum infections based on single and multicopy genes

PCR-based assays are the most sensitive and specific methods to detect malaria parasites

Prevalence of Plasmodium falciparum infection in pregnant women in Gabon

BACKGROUND: In areas where malaria is endemic, pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this risk ends with delivery and decreases with the number of pregnancies. Our study aimed to demonstrate relationships between malarial parasitaemia and age, gravidity and anaemia in pregnant women in Libreville, the capital city of Gabon. METHODS: Peripheral blood was collected from 311 primigravidae and women in their second pregnancy. Thick blood smears were checked, as were the results of haemoglobin electrophoresis. We also looked for the presence of anaemia, fever, and checked whether the volunteers had had chemoprophylaxis. The study was performed in Gabon where malaria transmission is intense and perennial. RESULTS: A total of 177 women (57%) had microscopic parasitaemia; 139 (64%)of them were primigravidae, 38 (40%) in their second pregnancy and 180 (64%) were teenagers. The parasites densities were also higher in primigravidae and teenagers. The prevalence of anaemia was 71% and was associated with microscopic Plasmodium falciparum parasitaemia: women with moderate or severe anaemia had higher parasite prevalences and densities. However, the sickle cell trait, fever and the use of chemoprophylaxis did not have a significant association with the presence of P. falciparum. CONCLUSIONS: These results suggest that the prevalence of malaria and the prevalence of anaemia, whether associated with malaria or not, are higher in pregnant women in Gabon. Primigravidae and young pregnant women are the most susceptible to infection. It is, therefore, urgent to design an effective regimen of malaria prophylaxis for this high risk population

Delayed-Onset Hemolytic Anemia in Patients with Travel-Associated Severe Malaria Treated with Artesunate, France, 2011–2013

French Artesunate Working GroupInternational audienceArtesunate is the most effective treatment for severe malaria. However, delayed-onset hemolytic anemia has been observed in ≈20% of travelers who receive artesunate, ≈60% of whom require transfusion. This finding could discourage physicians from using artesunate. We prospectively evaluated a cohort of 123 patients in France who had severe imported malaria that was treated with artesunate; our evaluation focused on outcome, adverse events, and postartesunate delayed-onset hemolysis (PADH). Of the 123 patients, 6 (5%) died. Overall, 97 adverse events occurred. Among the 78 patients who received follow-up for >8 days after treatment initiation, 76 (97%) had anemia, and 21 (27%) of the 78 cases were recorded as PADH. The median drop in hemoglobin levels was 1.3 g/dL; 15% of patients with PADH had hemoglobin levels of <7 g/dL, and 1 required transfusion. Despite the high incidence of PADH, the resulting anemia remained mild in 85% of cases. This reassuring result confirms the safety and therapeutic benefit of artesunate

Severe falciparum malaria in Gabonese children: clinical and laboratory features

BACKGROUND: Malaria continues to claim one to two million lives a year, mainly those of children in sub-Saharan Africa. Reduction in mortality depends, in part, on improving the quality of hospital care, the training of healthcare workers and improvements in public health. This study examined the prognostic indicators of severe falciparum malaria in Gabonese children. METHODS: An observational study examining the clinical presentations and laboratory features of severe malaria was conducted at the Centre Hospitalier de Libreville, Gabon over two years. Febrile children aged from 0 to 10 years with Plasmodium falciparum infection and one or more features of severe malaria were enrolled. RESULTS: Most children presenting with severe falciparum malaria were less than 5 years (92.3% of 583 cases). Anaemia was the most frequent feature of severe malaria (67.8% of cases), followed by respiratory distress (31%), cerebral malaria (24%) hyperlactataemia (16%) and then hypoglycaemia (10%). Anaemia was more common in children under 18 months old, while cerebral malaria usually occurred in those over 18 months. The overall case fatality rate was 9%. The prognostic indicators with the highest case fatality rates were coma/seizures, hyperlactataemia and hypoglycaemia, and the highest case fatality rate was in children with all three of these features. CONCLUSIONS: Prompt and appropriate, classification and treatment of malaria helps identify the most severely ill children and aids early and appropriate management of the severely ill child

Plasmodium falciparum Clearance Is Rapid and Pitting Independent in Immune Malian Children Treated With Artesunate for Malaria

Background. In Plasmodium falciparum-infected patients treated with artemisinins, parasitemia declines through so-called pitting, an innate splenic process that transforms infected red blood cells (iRBCs) into onceinfected RBCs (O-iRBCs). Methods. We measured pitting in 83 French travelers and 42 Malian children treated for malaria with artesunate. Results. In travelers, O-iRBCs peaked at 107.7% initial parasitemia. In Malian children aged 1.5-4 years, OiRBCs peaked at higher concentrations than in children aged 9-13 years (91.60% vs 31.95%; P = .0097). The parasite clearance time in older children was shorter than in younger children (P = .0001), and the decline in parasitemia in children aged 1.5-4 years often started 6 hours after treatment initiation, a lag phase generally absent in infants and older children. A 6-hour lag phase in artificial pitting of artesunate-exposed iRBCs was also observed in vitro. The proportion of iRBCs recognized by autologous immunoglobulin G (IgG) correlated with the parasite clearance time (r = −0.501; P = .0006) and peak O-iRBC concentration (r = −0.420; P = .0033). Conclusions. Antimalarial immunity correlates with fast artemisinin-induced parasite clearance and low pitting rates. In nonimmune populations, artemisinin-induced P. falciparum clearance is related to pitting and starts after a 6-hour lag phase. In immune populations, passively and naturally acquired immune mechanisms operating faster than pitting may exist. This mechanism may mitigate the emergence of artemisinin-resistant P. falciparum in Africa

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 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

Evidence of decline of malaria in the general hospital of Libreville, Gabon from 2000 to 2008

BACKGROUND: Substantial decline in malaria transmission, morbidity and mortality has been reported in several countries where new malaria control strategies have been implemented. In Gabon, the national malaria policy changed in 2003, according to the WHO recommendations. The trend in malaria morbidity was evaluated among febrile children before and after their implementation in Libreville, the capital city of Gabon. METHODS: From August 2000 to December 2008, febrile paediatric outpatients and inpatients, under 11 years of age, were screened for malaria by microscopic examination at the Malaria Clinical Research Unit (MCRU) located in the largest public hospital in Gabon. Climatic data were also collected. RESULTS: In total, 28,092 febrile children were examined; those under five years always represented more than 70%. The proportion of malaria-positive slides was 45% in 2000, and declined to 15% in 2008. The median age of children with a positive blood smear increased from 24(15-48) to 41(21-72) months over the study period (p < 0.01). Rainfall patterns had no impact on the decline observed throughout the study period. CONCLUSION: The decrease of malaria prevalence among febrile children during the last nine years is observed following the introduction of new strategies of malaria cases management, and may announce epidemiological changes. Moreover, preventive measures must be extended to children older than five years

Imported malaria in the mainland France from 1996 to 2016 : representativeness, assessment of the French National Reference Centre for malaria network and imported malaria risk modeling

La recrudescence des voyageurs vers les zones d'endémie palustre et le nombre élevé de cas importés ont accentué la nécessité de mettre en place une surveillance épidémiologique du paludisme. En dépit des mesures de prévention visant à réduire le risque d'infection chez les voyageurs, le nombre de cas de paludisme demeure élevé en France. Dans le cadre de la surveillance épidémiologique du paludisme, les cas rapportés en France pendant la période 1996-2016 ont été analysés et le système d'information et de surveillance du paludisme a été évalué. Une analyse des tendances épidémiologiques met en évidence les différents changements sur les caractéristiques épidémiologiques du paludisme en France au cours de deux dernières décennies. Une collaboration de recherche a été mise en place avec Santé publique France (SPF), l'Institut français de surveillance de la santé publique pour l’utilisation des données du registre national des causes de décès en médecine (CépiDc) et du Programme de Médicalisation du Système d’Information (PMSI) pour l’estimation du nombre de décès liés au paludisme en France. Nous avons utilisé les méthodes de capture-recapture à deux sources et les modèles log-linéaires pour estimer le nombre total de décès. Par ailleurs, de façon rétrospective, nous avons utilisé les données de trois enquêtes exhaustives sur le contrôle national de qualité en parasitologie pour estimer le nombre total des cas de paludisme en France. Il est ressorti de ce travail, que le système de surveillance du CNR du paludisme était stable au cours de la période d'étude, avec 85% des cas de paludisme rapportés au CNR du paludisme par 66 centres participants ayant déclaré constamment leurs cas au cours de la période d’étude, la sensibilité pour les décès était seulement de 38%, inférieure à celle des cas (52%). Sur le plan épidémiologique, les changements les plus frappants ont été l'augmentation de la proportion de cas de paludisme chez les individus d’origine africaine (de 53,5% en 1996 à 83,4% en 2016, la plupart des voyageurs qui visitent de la famille et des amis (VFR), 79,6% en 2016), une augmentation de l'âge médian des patients de +8 ans (africains, +10 ans et européens, +7 ans) et le doublement de la proportion de cas graves. En conclusion, ces changements dans les caractéristiques épidémiologiques des individus atteints de paludisme importé en France métropolitaine questionnent sur la stratégie actuelle de prévention pour les voyageurs. En termes de perspective, l’utilisation des enquêtes exhaustives et des méthodes de capture-recapture pourraient être des alternatives à des études longues et coûteuses permettant une évaluation quantitative des systèmes de surveillance, ainsi qu’une harmonisation des indicateurs de surveillance des maladies infectieuses en Europe.Increase in travellers to malaria-endemic areas and the higher incidence of imported malaria cases have accentuated the need to set up an early warning system for malaria control. Despite prevention measures aimed at reducing the risk of infection among travellers, the number of malaria cases remains high in France. In that case, malaria cases reported in France from 1996 through 2016 were analyzed and the malaria information and surveillance system was evaluated. Interestingly, collaboration has been set up with Santé Publique France (SPF) for the use of data from the French National Registry on medical causes of death (CépiDc) and the French national hospital discharge database (PMSI) in regards to estimating the number of malaria-related deaths in France. This was done by using a two-source capture-recapture methods and log-linear models. In addition, retrospectively, we used the data from three exhaustive surveys based on questionnaire sent to all the medical laboratories belonging to the national quality control in parasitology in collaboration with the national Agency for the safety of Medical Products (ANSM) to estimate the total number of malaria cases in France. Then, we described trends in epidemiologic characteristic of imported malaria in France from 1996 to 2016. It emerged from this work that our surveillance system was stable during the study period, with 85% of malaria cases reported by 66 of participating centres having regularly declared their cases during the study period, the sensitivity for death was only 38%, poor compared to that of cases (52%). At the epidemiological level, the most striking changes were the increase in the proportion of malaria cases among African individuals (from 53.5% in 1996 to 83.4% in 2016, most of them African VFRs, to 79.6% in 2016), the 8-year increase of the median age of the patients (African, 10 years and European, 7 years) and the doubling in the proportion of severe cases. What we have learned from this study is that these changes in the epidemiological characteristics of individuals suffering from malaria should imply a strengthening of malaria preventive strategy to alleviate the burden of the disease among travellers in France. In the last two decades, substantial progress has been made to enhance malaria surveillance in France by providing appropriate diagnostics and treatments, enhancing the French malaria surveillance system. In this situation, the excellent quality of the data, the sensibility of the captures, the stability of the network, and the large contribution of the correspondents to malaria network are useful as they allow validating results on a large scale. In perspective, the use of national surveys and capture-recapture methods could be alternatives to long and costly studies allowing a quantitative evaluation of surveillance systems and harmonisation of indicators for infectious diseases control in Europe. Furthermore, reducing the cost of malaria prophylaxis and national preventive campaign toward population at risk are essential to continue the downward trend of imported malaria incidence in France