Can treatment of malaria be restricted to parasitologically confirmed malaria? A school-based study in Benin in children with and without fever

<p>Abstract</p> <p>Background</p> <p>Applying the switch from presumptive treatment of malaria to new policies of anti-malarial prescriptions restricted to parasitologically-confirmed cases is a still unsolved challenge. Pragmatic studies can provide data on consequences of such a switch. In order to assess whether restricting anti-malarials to rapid diagnostic test (RDT)-confirmed cases in children of between five and 15 years of age is consistent with an adequate management of fevers, a school-based study was performed in Allada, Benin.</p> <p>Methods</p> <p>Children in the index group (with fever and a negative RDT) and the matched control group (without fever and a negative RDT) were not prescribed anti-malarials and actively followed-up during 14 days. Blood smears were collected at each assessment. Self-medication with chloroquine and quinine was assessed with blood spots. Malaria attacks during the follow-up were defined by persistent or recurrent fever concomitant to a positive malaria test.</p> <p>Results</p> <p>484 children were followed-up (242 in each group). At day 3, fever had disappeared in 94% of children from the index group. The incidence of malaria was similar (five cases in the index group and seven cases in the control group) between groups. Self-medication with chloroquine and quinine in this cohort was uncommon.</p> <p>Conclusions</p> <p>Applying a policy of restricting anti-malarials to RDT-confirmed cases is consistent with an adequate management of fevers in this population. Further studies on the management of fever in younger children are of upmost importance.</p

What would PCR assessment change in the management of fevers in a malaria endemic area? A school-based study in Benin in children with and without fever

<p>Abstract</p> <p>Background</p> <p>A recent school-based study in Benin showed that applying a policy of anti-malarial prescriptions restricted to parasitologically-confirmed cases on the management of fever is safe and feasible. Additional PCR data were analysed in order to touch patho-physiological issues, such as the usefulness of PCR in the management of malaria in an endemic area or the triggering of a malaria attack in children with submicroscopic malaria.</p> <p>Methods</p> <p>PCR data were prospectively collected in the setting of an exposed (with fever)/non exposed (without fever) study design. All children had a negative malaria rapid diagnostic test (RDT) at baseline, were followed up to day 14 and did not receive drugs with anti-malarial activity. The index group was defined by children with fever at baseline and the control group by children without fever at baseline. Children with submicroscopic malaria in these two groups were defined by a positive PCR at baseline.</p> <p>Results</p> <p>PCR was positive in 66 (27%) children of the index group and in 104 (44%) children of the control group respectively. The only significant factor positively related to PCR positivity at baseline was the clinical status (control group). When definition of malaria attacks included PCR results, no difference of malaria incidence was observed between the index and control groups, neither in the whole cohort, nor in children with submicroscopic malaria. The rate of undiagnosed malaria at baseline was estimated to 3.7% at baseline in the index group.</p> <p>Conclusions</p> <p>Treating all children with fever and a positive PCR would have led to a significant increase of anti-malarial consumption, with few benefits in terms of clinical events. Non malarial fevers do not or do not frequently trigger malaria attacks in children with submicroscopic malaria.</p

Prevalence of Vitamin A Deficiency in Pregnant and Lactating Women in the Republic of Congo

Vitamin A status in a sample of pregnant and lactating women living in several representative regions of Congo was assessed and compared between August and September 2004. This survey was conducted using a randomized two-stage cluster-sampling method with stratification on 90 clusters, each consisting of at least 15 women. Vitamin A status was determined in a total of 1,054 individuals, using the impression cytology with transfer (ICT) test, the modified relative dose response test (MRDR test) on dried blood spots (DBS), and clinical examination to detect signs of xerophthalmia. The clinical criterion defining vitamin A deficiency was the presence of active xerophthalmia (Bitot's spots [X1B]), active corneal disease), and/ or night blindness (XN stage). The prevalence of clinical signs of stage XN and X1B xerophthalmia in the Republic of Congo was found to be 16% and 19% respectively. The prevalence of clinical signs (X1B) was greater in the rural north than in urban areas, with a gradient running from urban (5%) to rural area (33%); 27% of all the ICT tests showed that the subjects were suffering from vitamin A deficiency. The deficiency rates were significantly higher (p<0.001) in urban surroundings (Brazzaville) than in the rural northern regions. The biochemical MRDR test showed the presence of vitamin A deficiency (≥0.06) in 26% of the mothers in Brazzaville compared to 6% in the town of Kouilou; 44% of the women had retinol levels of <10 µg/dL in the rural north whereas these percentages were significantly lower in the urban areas surveyed (chi-square=62.30, p<0.001). A significant correlation was found to exist (p<0.001) between the ICT test and the MRDR test on DBS. In the population as a whole, 30% of the mothers suffering from malarial attack had abnormally low MRDR levels (≥0.06) compared to no malaria. The results of the present study confirm that vitamin A deficiency is a serious public-health issue in pregnant and lactating mothers in the Republic of Congo

Rapid diagnostic tests failing to detect infections by Plasmodium falciparum encoding pfhrp2 and pfhrp3 genes in a non-endemic setting

International audienceBackground Rapid diagnostic tests (RDTs) detecting the histidine-rich protein 2 (PfHRP2) have a central position for the management of Plasmodium falciparum infections. Yet, variable detection of certain targeted motifs, low parasitaemia, but also deletion of pfhrp2 gene or its homologue pfhrp3, may result in false-negative RDT leading to misdiagnosis and delayed treatment. This study aimed at investigating the prevalence, and understanding the possible causes, of P. falciparum RDT-negative infections at Montpellier Academic Hospital, France. Methods The prevalence of falsely-negative RDT results reported before and after the introduction of a loop-mediated isothermal amplification (LAMP) assay, as part as the malaria screening strategy in January 2017, was analysed. Negative P. falciparum RDT infections were screened for pfhrp2 or pfhrp3 deletion; and exons 2 were sequenced to show a putative genetic diversity impairing PfHRP2 detection. Results The overall prevalence of P. falciparum negative RDTs from January 2006 to December 2018 was low (3/446). Whereas no cases were reported from 2006 to 2016 (0/373), period during which the malaria diagnostic screen was based on microscopy and RDT, prevalence increased up to 4.1% (3/73) between 2017 and 2018, when molecular detection was implemented for primary screening. Neither pfhrp2/3 deletion nor major variation in the frequency of repetitive epitopes could explain these false-negative RDT results. Conclusion This paper demonstrates the presence of pfhrp2 and pfhrp3 genes in three P. falciparum RDT-negative infections and reviews the possible reasons for non-detection of HRP2/3 antigens in a non-endemic setting. It highlights the emergence of falsely negative rapid diagnostic tests in a non-endemic setting and draws attention on the risk of missing malaria cases with low parasitaemia infections using the RDT plus microscopy-based strategy currently recommended by French authorities. The relevance of a novel diagnostic scheme based upon a LAMP assay is discussed

Cationic microbubbles and antibiotic-free miniplasmid for sustained ultrasound–mediated transgene expression in liver

International audienceDespite the increasing number of clinical trials in gene therapy, no ideal methods still allow non-viral gene transfer in deep tissues such as the liver. We were interested in ultrasound (US)-mediated gene delivery to provide long term liver expression. For this purpose, new positively charged microbubbles were designed and complexed with pFAR4, a highly efficient small length miniplasmid DNA devoid of antibiotic resistance sequence. Sonoporation parameters, such as insonation time, acoustic pressure and duration of plasmid injection were controlled under ultrasound imaging guidance. The optimization of these various parameters was performed by bioluminescence optical imaging of luciferase reporter gene expression in the liver. Mice were injected with 50 μg pFAR4-LUC either alone, or complexed with positively charged microbubbles, or co-injected with neutral MicroMarker™ microbubbles, followed by low ultrasound energy application to the liver. Injection of the pFAR4 encoding luciferase alone led to a transient transgene expression that lasted only for two days. The significant luciferase signal obtained with neutral microbubbles decreased over 2 days and reached a plateau with a level around 1 log above the signal obtained with pFAR4 alone. With the newly designed positively charged microbubbles, we obtained a much stronger bioluminescence signal which increased over 2 days. The 12-fold difference (p < 0.05) between MicroMarker™ and our positively charged microbubbles was maintained over a period of 6 months. Noteworthy, the positively charged microbubbles led to an improvement of 180-fold (p < 0.001) as regard to free pDNA using unfocused ultrasound performed at clinically tolerated ultrasound amplitude. Transient liver damage was observed when using the cationic microbubble-pFAR4 complexes and the optimized sonoporation parameters. Immunohistochemistry analyses were performed to determine the nature of cells transfected. The pFAR4 miniplasmid complexed with cationic microbubbles allowed to transfect mostly hepatocytes compared to its co-injection with MicroMarker™ which transfected more preferentially endothelial cells

Schematic representation of the <i>Plasmodium falciparum</i> mitochondrial genome.

<p>In green are represented the three protein coding genes of the mitochondrial genome of <i>Plasmodium</i> parasites. On the <i>Cytochrome b</i> gene, used for <i>Plasmodium</i> diagnostic in this study, the position of the two SNVs (single nucleotide variations) allowing to distinguish <i>P</i>. <i>falciparum</i> from the ape <i>Laveranias</i> is shown in orange.</p

Relationship between (i) the total number of reads sequenced in the “<i>P</i>. <i>vivax</i> and ape <i>Plasmodium</i>” positive controls and (ii) the total number of reads assigned to <i>P</i>. <i>vivax</i> or an ape <i>Plasmodium</i> species in the human samples.

<p>Relationship between (i) the total number of reads sequenced in the “<i>P</i>. <i>vivax</i> and ape <i>Plasmodium</i>” positive controls and (ii) the total number of reads assigned to <i>P</i>. <i>vivax</i> or an ape <i>Plasmodium</i> species in the human samples.</p

A. Schematic phylogenetic representation of relationships among <i>Plasmodium</i> species circulating in Central Africa; B. Location, in Gabon, of the 210 villages (red circles) where human blood samples were collected between 2005 and 2008.

<p>Distribution of the different sub-species of chimpanzees, bonobos and of gorillas in Central Africa is shown.</p