Diagnosis of neglected tropical diseases among patients with persistent digestive disorders (diarrhoea and/or abdominal pain ≥14 days): Pierrea multi-country, prospective, non-experimental case-control study.

BACKGROUND: Diarrhoea still accounts for considerable mortality and morbidity worldwide. The highest burden is concentrated in tropical areas where populations lack access to clean water, adequate sanitation and hygiene. In contrast to acute diarrhoea (<14 days), the spectrum of pathogens that may give rise to persistent diarrhoea (≥14 days) and persistent abdominal pain is poorly understood. It is conceivable that pathogens causing neglected tropical diseases play a major role, but few studies investigated this issue. Clinical management and diagnostic work-up of persistent digestive disorders in the tropics therefore remain inadequate. Hence, important aspects regarding the pathogenesis, epidemiology, clinical symptomatology and treatment options for patients presenting with persistent diarrhoea and persistent abdominal pain should be investigated in multi-centric clinical studies. METHODS/DESIGN: This multi-country, prospective, non-experimental case-control study will assess persistent diarrhoea (≥14 days; in individuals aged ≥1 year) and persistent abdominal pain (≥14 days; in children/adolescents aged 1-18 years) in up to 2000 symptomatic patients and 2000 matched controls. Subjects from Côte d'Ivoire, Indonesia, Mali and Nepal will be clinically examined and interviewed using a detailed case report form. Additionally, each participant will provide a stool sample that will be examined using a suite of diagnostic methods (i.e., microscopic techniques, rapid diagnostic tests, stool culture and polymerase chain reaction) for the presence of bacterial and parasitic pathogens. Treatment will be offered to all infected participants and the clinical treatment response will be recorded. Data obtained will be utilised to develop patient-centred clinical algorithms that will be validated in primary health care centres in the four study countries in subsequent studies. DISCUSSION: Our research will deepen the understanding of the importance of persistent diarrhoea and related digestive disorders in the tropics. A diversity of intestinal pathogens will be assessed for potential associations with persistent diarrhoea and persistent abdominal pain. Different diagnostic methods will be compared, clinical symptoms investigated and diagnosis-treatment algorithms developed for validation in selected primary health care centres. The findings from this study will improve differential diagnosis and evidence-based clinical management of digestive syndromes in the tropics. TRIAL REGISTRATION: ClinicalTrials.gov; identifier: NCT02105714 .

Molecular basis of allele-specific efficacy of a blood-stage malaria vaccine: vaccine development implications.

The disappointing efficacy of blood-stage malaria vaccines may be explained in part by allele-specific immune responses that are directed against polymorphic epitopes on blood-stage antigens. FMP2.1/AS02(A), a blood-stage candidate vaccine based on apical membrane antigen 1 (AMA1) from the 3D7 strain of Plasmodium falciparum, had allele-specific efficacy against clinical malaria in a phase II trial in Malian children. We assessed the cross-protective efficacy of the malaria vaccine and inferred which polymorphic amino acid positions in AMA1 were the targets of protective allele-specific immune responses. FMP2.1/AS02(A) had the highest efficacy against AMA1 alleles that were identical to the 3D7 vaccine-type allele at 8 highly polymorphic amino acid positions in the cluster 1 loop (c1L) but differed from 3D7 elsewhere in the molecule. Comparison of the incidence of vaccine-type alleles before and after vaccination in the malaria vaccine and control groups and examination of the patterns of allele change at polymorphic positions in consecutive malaria episodes suggest that the highly polymorphic amino acid position 197 in c1L was the most critical determinant of allele-specific efficacy. These results indicate that a multivalent AMA1 vaccine with broad efficacy could include only a limited set of key alleles of this extremely polymorphic antigen.

Multiplex PCR for bacterial, viral and protozoal pathogens in persistent diarrhoea or persistent abdominal pain in Côte d'Ivoire, Mali and Nepal.

In contrast to acute diarrhoea, the aetiology of persistent digestive disorders (≥ 14 days) is poorly understood in low-resource settings and conventional diagnostic approaches lack accuracy. In this multi-country study, we compared multiplex real-time PCR for enteric bacterial, parasitic and viral pathogens in stool samples from symptomatic patients and matched asymptomatic controls in Côte d'Ivoire, Mali and Nepal. Among 1826 stool samples, the prevalence of most pathogens was highest in Mali, being up to threefold higher than in Côte d'Ivoire and up to tenfold higher than in Nepal. In all settings, the most prevalent bacteria were EAEC (13.0-39.9%) and Campylobacter spp. (3.9-35.3%). Giardia intestinalis was the predominant intestinal protozoon (2.9-20.5%), and adenovirus 40/41 was the most frequently observed viral pathogen (6.3-25.1%). Significantly different prevalences between symptomatic and asymptomatic individuals were observed for Campylobacter, EIEC and ETEC in the two African sites, and for norovirus in Nepal. Multiple species pathogen infection was common in Côte d'Ivoire and Mali, but rarely found in Nepal. We observed that molecular testing detected multiple enteric pathogens and showed low discriminatory accuracy to distinguish between symptomatic and asymptomatic individuals. Yet, multiplex PCR allowed for direct comparison between different countries and revealed considerable setting-specificity.

Use of a pLDH-based dipstick in the diagnostic and therapeutic follow-up of malaria patients in Mali.

BACKGROUND: Malaria is a major public health problem in Mali and diagnosis is typically based on microscopy. Microscopy requires a well trained technician, a reliable power source, a functioning microscope and adequate supplies. The scarcity of resources of community health centres (CHC) does not allow for such a significant investment in only one aspect of malaria control. In this context, Rapid Diagnostic Tests (RDTs) may improve case management particularly in remote areas. METHODS: This multicentre study included 725 patients simultaneously screened with OptiMal-IT test and thick smears for malaria parasite detection. While evaluating the therapeutic efficacy of choroquine in 2 study sites, we compared the diagnostic values of thick smear microscopy to OptiMal-IT test applying the WHO 14 days follow-up scheme using samples collected from 344 patients. RESULTS: The sensitivity and the specificity of OptiMal-IT compared to thick smear was 97.2% and 95.4%, whereas the positive and negative predictive values were 96.7 and 96.1%, respectively. The percent agreement between the two diagnostic tests was 0.93. The two tests were comparable in detecting malaria at day 0, day 3 and day 14. The only difference was observed at day 7 due to high gametocytemia. Subjectively, health care providers found OptiMal-IT easier to use and store under field conditions. CONCLUSION: OptiMal-IT test revealed similar results when compared to microscopy which is considered the gold standard for malaria diagnostics. The test was found to have a short processing time and was easier to use. These advantages may improve malaria case management by providing a diagnostic and drug efficacy follow-up tool to peripheral health centres with limited resources.

Lack of allele-specific efficacy of a bivalent AMA1 malaria vaccine.

BACKGROUND: Extensive genetic diversity in vaccine antigens may contribute to the lack of efficacy of blood stage malaria vaccines. Apical membrane antigen-1 (AMA1) is a leading blood stage malaria vaccine candidate with extreme diversity, potentially limiting its efficacy against infection and disease caused by Plasmodium falciparum parasites with diverse forms of AMA1. METHODS: Three hundred Malian children participated in a Phase 2 clinical trial of a bivalent malaria vaccine that found no protective efficacy. The vaccine consists of recombinant AMA1 based on the 3D7 and FVO strains of P. falciparum adjuvanted with aluminum hydroxide (AMA1-C1). The gene encoding AMA1 was sequenced from P. falciparum infections experienced before and after immunization with the study vaccine or a control vaccine. Sequences of ama1 from infections in the malaria vaccine and control groups were compared with regard to similarity to the vaccine antigens using several measures of genetic diversity. Time to infection with parasites carrying AMA1 haplotypes similar to the vaccine strains with respect to immunologically important polymorphisms and the risk of infection with vaccine strain haplotypes were compared. RESULTS: Based on 62 polymorphic AMA1 residues, 186 unique ama1 haplotypes were identified among 315 ama1 sequences that were included in the analysis. Eight infections had ama1 sequences identical to 3D7 while none were identical to FVO. Several measures of genetic diversity showed that ama1 sequences in the malaria vaccine and control groups were comparable both at baseline and during follow up period. Pre- and post-immunization ama1 sequences in both groups all had a similar degree of genetic distance from FVO and 3D7 ama1. No differences were found in the time of first clinical episode or risk of infection with an AMA1 haplotype similar to 3D7 or FVO with respect to a limited set of immunologically important polymorphisms found in the cluster 1 loop of domain I of AMA1. CONCLUSION: This Phase 2 trial of a bivalent AMA1 malaria vaccine found no evidence of vaccine selection or strain-specific efficacy, suggesting that the extreme genetic diversity of AMA1 did not account for failure of the vaccine to provide protection.

Artemisinin-based combinations versus amodiaquine plus sulphadoxine-pyrimethamine for the treatment of uncomplicated malaria in Faladje, Mali.

BACKGROUND: Because of the emergence of chloroquine resistance in Mali, artemether-lumefantrine (AL) or artesunate-amodiaquine (AS+AQ) are recommended as first-line therapy for uncomplicated malaria, but have not been available in Mali until recently because of high costs. METHODS: From July 2005 to January 2006, a randomized open-label trial of three oral antimalarial combinations, namely AS+AQ, artesunate plus sulphadoxine-pyrimethamine (AS+SP), and amodiaquine plus sulphadoxine-pyrimethamine (AQ+SP), was conducted in Faladje, Mali. Parasite genotyping by polymerase chain reaction (PCR) was used to distinguish new from recrudescent Plasmodium falciparum infections. RESULTS: 397 children 6 to 59 months of age with uncomplicated Plasmodium falciparum malaria were enrolled, and followed for 28 days to assess treatment efficacy. Baseline characteristics were similar in all three treatment groups. The uncorrected rates of adequate clinical and parasitologic response (ACPR) were 55.7%, 90.8%, and 97.7% in AS+AQ, AS+SP, and AQ+SP respectively (p < 0.001); after PCR correction ACPR rates were similar among treatment groups: 95.4%, 96.9%, and 99.2% respectively (p = 0.17). Mean haemoglobin concentration increased across all treatment groups from Day 0 (9.82 +/- 1.68 g/dL) to Day 28 (10.78 +/- 1.49 g/dL) (p < 0.001), with the greatest improvement occurring in children treated with AQ+SP. On Day 2, the prevalence of parasitaemia was significantly greater among children treated with AQ+SP (50.8%) than in children treated with AS+AQ (10.5%) or AS+SP (10.8%) (p < 0.001). No significant difference in gametocyte carriage was found between groups during the follow-up period. CONCLUSION: The combination of AQ+SP provides a potentially low cost alternative for treatment of uncomplicated P. falciparum infection in Mali and appears to have the added value of longer protective effect against new infection.

Performance Outcomes from Africa-Based Malaria Diagnostic Competency Assessment Courses.

The U.S. President's Malaria Initiative-funded MalariaCare project implemented an external quality assurance scheme to support malaria diagnostics and case management across a spectrum of health facilities in participating African countries. A component of this program was a 5-day, malaria diagnostic competency assessment (MDCA) course for health facility laboratory staff conducting malaria microscopy. The MDCA course provided a method to quantify participant skill levels in microscopic examination of malaria across three major diagnosis areas: parasite detection, species identification, and parasite quantification. A total of 817 central-, regional-, and peripheral-level microscopists from 45 MDCA courses across nine African countries were included in the analysis. Differences in mean scores with respect to daily marginal performance were positive and statistically significant (P < 0.001) for each challenge type across all participants combined. From pretest to assessment day 4, mean scores for parasite detection, species identification, and parasite quantification increased by 19.1, 34.9, and 38.2 percentage points, respectively. In addition, sensitivity and specificity increased by 20.8 and 13.8 percentage points, respectively, by assessment day 4. Furthermore, the ability of MDCA participants to accurately report Plasmodium falciparum species when present increased from 44.5% at pretest to 67.1% by assessment day 4. The MDCA course rapidly improved the microscopy performance of participants over a short period of time. Because of its rigor, the MDCA course could serve as a mechanism for measuring laboratory staff performance against country-specific minimum competency standards and could easily be adapted to serve as a national certification course.

Prevalence of Giardia intestinalis Infection in Schistosomiasis-Endemic Areas in South-Central Mali.

Intestinal parasite infections are frequent causes of diarrhea and malnutrition among children in the tropics. Transmission of helminths and intestinal protozoa is intimately connected with conditions of poverty, including inadequate sanitation and hygiene. Concurrent infections with several intestinal pathogens may lead to excess morbidity. Yet, there is a paucity of epidemiological data from Mali. In this study, stool samples from 56 individuals, aged 2-63 years, from Bamako and Niono, south-central Mali were examined for intestinal parasites using stool microscopy. Additionally, stool samples were subjected to a rapid diagnostic test (RDT) and polymerase chain reaction (PCR) for the detection of Cryptosporidium spp. and Giardia intestinalis. The predominant pathogens were Schistosoma mansoni and G. intestinalis with prevalences of 41% and 38%, respectively. Hymenolepis nana was detected in 4% of the participants, while no eggs of soil-transmitted helminths were found. Concurrent infections with G. intestinalis and S. mansoni were diagnosed in 16% of the participants. For the detection of G. intestinalis, PCR was more sensitive (100%) than RDT (62%) and microscopy (48%). As helminth-protozoa coinfections might have important implications for morbidity control programs, future studies should employ diagnostic tools beyond stool microscopy to accurately assess the co-endemicity of giardiasis and schistosomiasis.

Effect of Supportive Supervision on Malaria Microscopy Competencies in Sub-Saharan Africa.

Although light microscopy is the reference standard for diagnosing malaria, maintaining skills over time can be challenging. Between 2015 and 2017, the U.S. President's Malaria Initiative-funded MalariaCare project supported outreach training and supportive supervision (OTSS) visits at 1,037 health facilities in seven African countries to improve performance in microscopy slide preparation, staining, and reading. During these visits, supervisors observed and provided feedback to health-care workers (HCWs) performing malaria microscopy using a 30-step checklist. Of the steps observed in facilities with at least three visits, the proportion of HCWs that performed each step correctly at baseline ranged from 63.2% to 94.2%. The change in the proportion of HCWs performing steps correctly by the third visit ranged from 16.7 to 23.6 percentage points (n = 916 observations). To assess the overall improvement, facility scores were calculated based on the steps performed correctly during each visit. The mean score at baseline was 85.7%, demonstrating a high level of performance before OTSS. Regression analysis predicted an improvement in facility scores of 3.6 percentage points (P < 0.001) after three visits across all countries. In reference-level facilities with consistently high performance on microscopy procedures and parasite detection, quality assurance (QA) mechanisms could prioritize more advanced skills, such as proficiency testing for parasite counting and species identification. However, in settings with high staff turnover and declining use of microscopy in favor of rapid diagnostic tests, additional supervision visits and/or additional QA measures may be required to improve and maintain performance.

Impact of a malaria intervention package in schools on Plasmodium infection, anaemia and cognitive function in schoolchildren in Mali: a pragmatic cluster-randomised trial.

BACKGROUND: School-aged children are rarely targeted by malaria control programmes, yet the prevalence of Plasmodium infection in primary school children often exceeds that seen in younger children and could affect haemoglobin concentration and school performance. METHODS: A cluster-randomised trial was carried out in 80 primary schools in southern Mali to evaluate the impact of a school-based malaria intervention package. Intervention schools received two interventions sequentially: (1) teacher-led participatory malaria prevention education, combined with distribution of long-lasting insecticidal nets (LLINs), followed 7 months later at the end of the transmission season by (2) mass delivery of artesunate and sulfadoxine-pyrimethamine administered by teachers, termed intermittent parasite clearance in schools (IPCs). Control schools received LLINs as part of the national universal net distribution programme. The impact of the interventions on malaria and anaemia was evaluated over 20 months using cross-sectional surveys in a random subset of 38 schools(all classes), with a range of cognitive measures (sustained attention, visual search, numeracy, vocabulary and writing) assessed in a longitudinal cohort of children aged 9-12 years in all 80 schools. RESULTS: Delivery of a single round of IPCs was associated with dramatic reductions in malaria parasitaemia (OR 0.005, 95% CI 0.002 to 0.011, p<0.001) and gametocyte carriage (OR 0.02, 95% CI 0.00 to 0.17, p<0.001) in intervention compared with control schools. This effect was sustained for 6 months until the beginning of the next transmission season. IPCs was also associated with a significant decrease in anaemia (OR 0.56, 95% CI 0.40 to 0.78, p=0.001), and increase in sustained attention (difference +0.23, 95% CI 0.10 to 0.36, p<0.001). There was no evidence of impact on other cognitive measures. CONCLUSION: The combination of malaria prevention education, LLINs and IPCs can reduce anaemia and improve sustained attention of school children in areas of highly seasonal transmission. These findings highlight the impact of asymptomatic malaria infection on cognitive performance in schoolchildren and the benefit of IPCs in reducing this burden. Additionally, malaria control in schools can help diminish the infectious reservoir that sustains Plasmodium transmission.

Promoting good clinical laboratory practices and laboratory accreditation to support clinical trials in sub-Saharan Africa.

Laboratory capacity in the developing world frequently lacks quality management systems (QMS) such as good clinical laboratory practices, proper safety precautions, and adequate facilities; impacting the ability to conduct biomedical research where it is needed most. As the regulatory climate changes globally, higher quality laboratory support is needed to protect study volunteers and to accurately assess biological parameters. The University of Bamako and its partners have undertaken a comprehensive QMS plan to improve quality and productivity using the Clinical and Laboratory Standards Institute standards and guidelines. The clinical laboratory passed the College of American Pathologists inspection in April 2010, and received full accreditation in June 2010. Our efforts to implement high-quality standards have been valuable for evaluating safety and immunogenicity of malaria vaccine candidates in Mali. Other disease-specific research groups in resource-limited settings may benefit by incorporating similar training initiatives, QMS methods, and continual improvement practices to ensure best practices.

A randomized and controlled Phase 1 study of the safety and immunogenicity of the AMA1-C1/Alhydrogel + CPG 7909 vaccine for Plasmodium falciparum malaria in semi-immune Malian adults.

A double blind, randomized and controlled Phase 1 clinical trial was conducted to assess the safety and immunogenicity in malaria-exposed adults of the Plasmodium falciparum blood stage vaccine candidate Apical Membrane Antigen 1-Combination 1 (AMA1-C1)/Alhydrogel with and without the novel adjuvant CPG 7909. Participants were healthy adults 18-45 years old living in the village of Donéguébougou, Mali. A total of 24 participants received 2 doses one month apart of either 80 microg AMA1-C1/Alhydrogel or 80 microg AMA1-C1/Alhydrogel + 564 microg CPG 7909. The study started in October 2007 and completed follow up in May 2008. Both vaccines were well tolerated, with only mild local adverse events and no systemic adverse events judged related to vaccination. The difference in antibody responses were over 2-fold higher in the group receiving CPG 7909 for all time points after second vaccination and the differences are statistically significant (all p<0.05). This is the first use of the novel adjuvant CPG 7909 in a malaria-exposed population.

A randomized controlled phase 2 trial of the blood stage AMA1-C1/Alhydrogel malaria vaccine in children in Mali.

A double blind, randomized, controlled Phase 2 clinical trial was conducted to assess the safety, immunogenicity, and biologic impact of the vaccine candidate Apical Membrane Antigen 1-Combination 1 (AMA1-C1), adjuvanted with Alhydrogel. Participants were healthy children 2-3 years old living in or near the village of Bancoumana, Mali. A total of 300 children received either the study vaccine or the comparator. No impact of vaccination was seen on the primary endpoint, the frequency of parasitemia measured as episodes >3000/microL/day at risk. There was a negative impact of vaccination on the hemoglobin level during clinical malaria, and mean incidence of hemoglobin <8.5 g/dL, in the direction of lower hemoglobin in the children who received AMA1-C1, although these differences were not significant after correction for multiple tests. These differences were not seen in the second year of transmission.