Umberto D’Alessandro

HIV-1 Immune Suppression and Antimalarial Treatment Outcome in Zambian Adults with Uncomplicated Malaria

BACKGROUND Human immunodeficiency virus (HIV)-1 infected adults with low CD4 cell count have a higher risk of malaria infection and clinical malaria. We assessed the influence that HIV-1 immune suppression has on the efficacy of antimalarial treatment in adults with uncomplicated malaria. METHODS This clinical trial included 971 Zambian adults with uncomplicated malaria. Patients were tested for HIV-1, and, if positive, a CD4 cell count was assessed. The primary outcome was recurrent parasitemia corrected by molecular genotyping within 45 days after treatment. RESULTS HIV-1 infection was detected in 33% (320/971) of adult patients with malaria. Treatment failure was not associated with HIV-1 infection (relative risk [RR], 1.12 [95% confidence interval {CI}, 0.82-1.53]; P=.45). HIV-1-infected patients with a CD4 cell count <300 cells/microL had an increased risk of recurrent parasitemia, compared with those with a CD4 cell count >or=300 cells/microL (RR, 2.24 [95% CI, 1.20-4.14]; P=.01). After genotyping, the risk of recrudescence was higher in HIV-1-infected patients with a CD4 cell count <300 cells/microL than in the other patients with malaria (RR, 1.67 [95% CI, 1.13-2.47]; P=.02). CONCLUSION HIV-1-infected patients with malaria with a CD4 cell count <300 cells/microL have a higher risk of experiencing a recrudescent infection, compared with those with a CD4 cell count >or=300 cells/microL or without HIV-1 infection. Trial registered at http://www.clinicaltrials.gov/; reference number NCT00304980.

High Complexity of Plasmodium vivax Infections in Symptomatic Patients from a Rural Community in Central Vietnam Detected by Microsatellite Genotyping

Fourteen published and three newly identified polymorphic microsatellites were used to genotype 69 Plasmodium vivax samples obtained from 39 patients detected over a period of two years who lived in a rural community of central Vietnam. All samples were polyclonal with an average expected heterozygosity of 0.86. Among the 39 patients, 16 experienced 1–5 recurrent episodes of P. vivax malaria, most of them (83%) with a different genotype profile compared with previous infections. The minimal set of microsatellites required for differentiating the genotype profiles of the recurrent infections compared with the full set of 17 microsatellites was explored. A combination of five markers was sufficient to identify all recurrent infections with an unrelated or different genotype profile compared with all previous episodes.

CD4 T-cell count and HIV-1 infection in adults with uncomplicated malaria

Background:HIV-1-negative children with malaria have reversible lymphocyte and CD4 count decreases. We assessed the impact of malaria parasitemia on the absolute CD4 count in both HIV-1-infected and non-HIV-infected adults. Methods:In Ndola, Zambia, at the health-center level, we treated 327 nonpregnant adults for confirmed, uncomplicated, clinical malaria. We assessed HIV-1 status, CD4 count, and HIV-1 viral load (if HIV-1-infected) at enrollment and at 28 and 45 days after treatment. Results:After successful antimalarial treatment, the median CD4 count at day 28 of follow-up increased from 468 to 811 cells/μL in HIV-1-negative and from 297 to 447 cells/μL in HIV-1-positive patients (paired t test, P < 0.001 for both). CD4 count increment was inversely correlated with CD4 count at day 0 in both HIV-1-negative (P < 0.001) and HIV-1-positive patients (P = 0.03). After successful treatment, the proportion of patients with CD4 count <200/μL at day 45 decreased from 9.6% to 0% in HIV-1-negative and from 28.7% to 13.2% in HIV-1-positive malaria patients (P < 0.001 for both). In patients with detectable but mostly asymptomatic parasitemia, CD4 count and, if HIV-1-infected, viral load at day 45 of follow-up were similar to those observed at enrollment. Conclusion:Interpretation of absolute CD4 count might be biased during or just after a clinical malaria episode. Therefore, in malaria-endemic areas, before taking any decision on the management of HIV-1-positive individuals, their malaria status should be assessed.

Hotspots of Malaria Transmission in the Peruvian Amazon: Rapid Assessment through a Parasitological and Serological Survey.

Background With low and markedly seasonal malaria transmission, increasingly sensitive tools for better stratifying the risk of infection and targeting control interventions are needed. A cross-sectional survey to characterize the current malaria transmission patterns, identify hotspots, and detect recent changes using parasitological and serological measures was conducted in three sites of the Peruvian Amazon. Material and Methods After full census of the study population, 651 participants were interviewed, clinically examined and had a blood sample taken for the detection of malaria parasites (microscopy and PCR) and antibodies against P. vivax (PvMSP119, PvAMA1) and P. falciparum (PfGLURP, PfAMA1) antigens by ELISA. Risk factors for malaria infection (positive PCR) and malaria exposure (seropositivity) were assessed by multivariate survey logistic regression models. Age-specific seroprevalence was analyzed using a reversible catalytic conversion model based on maximum likelihood for generating seroconversion rates (SCR, λ). SaTScan was used to detect spatial clusters of serology-positive individuals within each site. Results The overall parasite prevalence by PCR was low, i.e. 3.9% for P. vivax and 6.7% for P. falciparum, while the seroprevalence was substantially higher, 33.6% for P. vivax and 22.0% for P. falciparum, with major differences between study sites. Age and location (site) were significantly associated with P. vivax exposure; while location, age and outdoor occupation were associated with P. falciparum exposure. P. falciparum seroprevalence curves showed a stable transmission throughout time, while for P. vivax transmission was better described by a model with two SCRs. The spatial analysis identified well-defined clusters of P. falciparum seropositive individuals in two sites, while it detected only a very small cluster of P. vivax exposure. Conclusion The use of a single parasitological and serological malaria survey has proven to be an efficient and accurate method to characterize the species specific heterogeneity in malaria transmission at micro-geographical level as well as to identify recent changes in transmission.

Characterizing Types of Human Mobility to Inform Differential and Targeted Malaria Elimination Strategies in Northeast Cambodia.

Human population movements currently challenge malaria elimination in low transmission foci in the Greater Mekong Subregion. Using a mixed-methods design, combining ethnography (n = 410 interviews), malariometric data (n = 4996) and population surveys (n = 824 indigenous populations; n = 704 Khmer migrants) malaria vulnerability among different types of mobile populations was researched in the remote province of Ratanakiri, Cambodia. Different structural types of human mobility were identified, showing differential risk and vulnerability. Among local indigenous populations, access to malaria testing and treatment through the VMW-system and LLIN coverage was high but control strategies failed to account for forest farmers’ prolonged stays at forest farms/fields (61% during rainy season), increasing their exposure (p = 0.002). The Khmer migrants, with low acquired immunity, active on plantations and mines, represented a fundamentally different group not reached by LLIN-distribution campaigns since they were largely unregistered (79%) and unaware of the local VMW-system (95%) due to poor social integration. Khmer migrants therefore require control strategies including active detection, registration and immediate access to malaria prevention and control tools from which they are currently excluded. In conclusion, different types of mobility require different malaria elimination strategies. Targeting mobility without an in-depth understanding of malaria risk in each group challenges further progress towards elimination.

Pathogen Genotyping in Polyclonal Infections: Application of a Fluorogenic Polymerase–Chain-Reaction Assay in Malaria

Pathogen genotyping of polyclonal infections is limited by 2 major drawbacks: (1). how to establish whether multiple mutations detected in 1 gene belong to the same clone and (2). how to evaluate the proportion of different genotypes in a given sample. For drug-resistance genotyping in Plasmodium falciparum malaria, we address these problems by using a fluorogenic assay that combines fluorescence-resonance energy transfer, between fluorophores present on a probe and a polymerase-chain-reaction primer, and a melt-curve analysis. We demonstrate that this tool allows a more accurate insight into the P. falciparum populations present in complex biological samples.

Population Genetics of Plasmodium vivax in the Peruvian Amazon.

Background Characterizing the parasite dynamics and population structure provides useful information to understand the dynamic of transmission and to better target control interventions. Despite considerable efforts for its control, vivax malaria remains a major health problem in Peru. In this study, we have explored the population genetics of Plasmodium vivax isolates from Iquitos, the main city in the Peruvian Amazon, and 25 neighbouring peri-urban as well as rural villages along the Iquitos-Nauta Road. Methodology/ Results From April to December 2008, 292 P. vivax isolates were collected and successfully genotyped using 14 neutral microsatellites. Analysis of the molecular data revealed a similar proportion of monoclonal and polyclonal infections in urban areas, while in rural areas monoclonal infections were predominant (p = 0.002). Multiplicity of infection was higher in urban (MOI = 1.5–2) compared to rural areas (MOI = 1) (p = 0.003). The level of genetic diversity was similar in all areas (He = 0.66–0.76, p = 0.32) though genetic differentiation between areas was substantial (PHIPT = 0.17, p<0.0001). Principal coordinate analysis showed a marked differentiation between parasites from urban and rural areas. Linkage disequilibrium was detected in all the areas (IAs = 0.08–0.49, for all p<0.0001). Gene flow among the areas was stablished through Bayesian analysis of migration models. Recent bottleneck events were detected in 4 areas and a recent parasite expansion in one of the isolated areas. In total, 87 unique haplotypes grouped in 2 or 3 genetic clusters described a sub-structured parasite population. Conclusion/Significance Our study shows a sub-structured parasite population with clonal propagation, with most of its components recently affected by bottleneck events. Iquitos city is the main source of parasite spreading for all the peripheral study areas. The routes of transmission and gene flow and the reduction of the parasite population described are important from the public health perspective as well for the formulation of future control policies.

Serogroup W135 meningococcal disease, The Gambia, 2012.

In 2012, an outbreak of Neisseria meningitidis serogroup W135 occurred in The Gambia. The attack rate was highest among young children. The associated risk factors were male sex, contact with meningitis patients, and difficult breathing. Enhanced surveillance facilitates early epidemic detection, and multiserogroup conjugate vaccine could reduce meningococcal epidemics in The Gambia.

First-trimester artemisinin derivatives and quinine treatments and the risk of adverse pregnancy outcomes in Africa and Asia: A meta-analysis of observational studies.

Background Animal embryotoxicity data, and the scarcity of safety data in human pregnancies, have prevented artemisinin derivatives from being recommended for malaria treatment in the first trimester except in lifesaving circumstances. We conducted a meta-analysis of prospective observational studies comparing the risk of miscarriage, stillbirth, and major congenital anomaly (primary outcomes) among first-trimester pregnancies treated with artemisinin derivatives versus quinine or no antimalarial treatment. Methods and findings Electronic databases including Medline, Embase, and Malaria in Pregnancy Library were searched, and investigators contacted. Five studies involving 30,618 pregnancies were included; four from sub-Saharan Africa (n = 6,666 pregnancies, six sites) and one from Thailand (n = 23,952). Antimalarial exposures were ascertained by self-report or active detection and confirmed by prescriptions, clinic cards, and outpatient registers. Cox proportional hazards models, accounting for time under observation and gestational age at enrollment, were used to calculate hazard ratios. Individual participant data (IPD) meta-analysis was used to combine the African studies, and the results were then combined with those from Thailand using aggregated data meta-analysis with a random effects model. There was no difference in the risk of miscarriage associated with the use of artemisinins anytime during the first trimester (n = 37/671) compared with quinine (n = 96/945; adjusted hazard ratio [aHR] = 0.73 [95% CI 0.44, 1.21], I2 = 0%, p = 0.228), in the risk of stillbirth (artemisinins, n = 10/654; quinine, n = 11/615; aHR = 0.29 [95% CI 0.08–1.02], p = 0.053), or in the risk of miscarriage and stillbirth combined (pregnancy loss) (aHR = 0.58 [95% CI 0.36–1.02], p = 0.099). The corresponding risks of miscarriage, stillbirth, and pregnancy loss in a sensitivity analysis restricted to artemisinin exposures during the embryo sensitive period (6–12 wk gestation) were as follows: aHR = 1.04 (95% CI 0.54–2.01), I2 = 0%, p = 0.910; aHR = 0.73 (95% CI 0.26–2.06), p = 0.551; and aHR = 0.98 (95% CI 0.52–2.04), p = 0.603. The prevalence of major congenital anomalies was similar for first-trimester artemisinin (1.5% [95% CI 0.6%–3.5%]) and quinine exposures (1.2% [95% CI 0.6%–2.4%]). Key limitations of the study include the inability to control for confounding by indication in the African studies, the paucity of data on potential confounders, the limited statistical power to detect differences in congenital anomalies, and the lack of assessment of cardiovascular defects in newborns. Conclusions Compared to quinine, artemisinin treatment in the first trimester was not associated with an increased risk of miscarriage or stillbirth. While the data are limited, they indicate no difference in the prevalence of major congenital anomalies between treatment groups. The benefits of 3-d artemisinin combination therapy regimens to treat malaria in early pregnancy are likely to outweigh the adverse outcomes of partially treated malaria, which can occur with oral quinine because of the known poor adherence to 7-d regimens. Review registration PROSPERO CRD42015032371

Transdermal Diagnosis of Malaria Using Vapor Nanobubbles

Our laser device rapidly and noninvasively detected malaria in a patient and identified parasite-positive mosquitoes.