Journal Article > ResearchFull Text
Open Forum Infect Dis. 2 May 2024; Volume 11 (Issue 5); ofae221.; DOI:10.1093/ofid/ofae221
Moretó-Planas L, Mahajan R, Fidelle Nyikayo L, Ajack YBP, Tut Chol B, et al.
Open Forum Infect Dis. 2 May 2024; Volume 11 (Issue 5); ofae221.; DOI:10.1093/ofid/ofae221
BACKGROUND
Over half of childhood tuberculosis (TB) remains undiagnosed yearly. WHO recommends Xpert-Ultra as a first paediatric diagnosis test, but microbiological confirmation remains low. We aimed to determine the diagnostic performance of Xpert-Ultra on stool and urine in presumptive paediatric TB cases in two high-TB burden settings.
METHODS
This Médecins sans Frontières cross-sectional multicentric study took place at Simão Mendes hospital, Guinea-Bissau (July 2019 to April 2020) and in Malakal hospital, South Sudan (April 2021 to June 2023). Children 6 months to 15 years with presumptive TB underwent clinical and laboratory assessment, with one respiratory and/or extrapulmonary sample (gold standard (GS)), one stool and one urine specimen analysed with Xpert-Ultra.
RESULTS
A total of 563 children were enrolled in the study, 133 from Bissau, 400 from Malakal; 30 were excluded. Confirmation of TB was achieved in 75 (14.1%) while 248 (46.5%) had unconfirmed TB. Of 553 with GS specimen, the overall diagnostic yield was 12.4% (66/533). A total of 493 and 524 samples were used to evaluate Xpert-Ultra on stool and on urine, respectively. Compared to GS, sensitivity and specificity of Xpert-Ultra on stool were 62.5%(95%CI:49.4-74) and 98.3%(95%CI:96.7-99.2), whereas on urine were 13.9%(95%CI:7.5-24.3) and 99.4%(95%CI:98.1-99.8), respectively. Nine patients were positive on stool and/or urine but negative on GS.
CONCLUSIONS
Xpert-Ultra on stool showed moderate to high sensitivity and high specificity when compared to GS and an added diagnostic yield when GS was negative. Xpert-Ultra on stool was useful in extrapulmonary cases. Xpert-Ultra in urine showed low test performance.
Over half of childhood tuberculosis (TB) remains undiagnosed yearly. WHO recommends Xpert-Ultra as a first paediatric diagnosis test, but microbiological confirmation remains low. We aimed to determine the diagnostic performance of Xpert-Ultra on stool and urine in presumptive paediatric TB cases in two high-TB burden settings.
METHODS
This Médecins sans Frontières cross-sectional multicentric study took place at Simão Mendes hospital, Guinea-Bissau (July 2019 to April 2020) and in Malakal hospital, South Sudan (April 2021 to June 2023). Children 6 months to 15 years with presumptive TB underwent clinical and laboratory assessment, with one respiratory and/or extrapulmonary sample (gold standard (GS)), one stool and one urine specimen analysed with Xpert-Ultra.
RESULTS
A total of 563 children were enrolled in the study, 133 from Bissau, 400 from Malakal; 30 were excluded. Confirmation of TB was achieved in 75 (14.1%) while 248 (46.5%) had unconfirmed TB. Of 553 with GS specimen, the overall diagnostic yield was 12.4% (66/533). A total of 493 and 524 samples were used to evaluate Xpert-Ultra on stool and on urine, respectively. Compared to GS, sensitivity and specificity of Xpert-Ultra on stool were 62.5%(95%CI:49.4-74) and 98.3%(95%CI:96.7-99.2), whereas on urine were 13.9%(95%CI:7.5-24.3) and 99.4%(95%CI:98.1-99.8), respectively. Nine patients were positive on stool and/or urine but negative on GS.
CONCLUSIONS
Xpert-Ultra on stool showed moderate to high sensitivity and high specificity when compared to GS and an added diagnostic yield when GS was negative. Xpert-Ultra on stool was useful in extrapulmonary cases. Xpert-Ultra in urine showed low test performance.
Journal Article > ResearchFull Text
Front Epidemiol. 21 March 2024; Volume 4; 1309149.; DOI:10.3389/fepid.2024.1309149
Gutierrez R, Landa M, Sambou M, Bassane H, Dia N, et al.
Front Epidemiol. 21 March 2024; Volume 4; 1309149.; DOI:10.3389/fepid.2024.1309149
BACKGROUND
With growing use of parasitological tests to detect malaria and decreasing incidence of the disease in Africa; it becomes necessary to increase the understanding of causes of non-malaria acute febrile illness (NMAFI) towards providing appropriate case management. This research investigates causes of NMAFI in pediatric out-patients in rural Guinea-Bissau.
METHODS
Children 0–5 years presenting acute fever (≥38°) or history of fever, negative malaria rapid diagnostic test (mRDT) and no signs of specific disease were recruited at the out-patient clinic of 3 health facilities in Bafatá province during 54 consecutive weeks (dry and rainy season). Medical history was recorded and blood, nasopharyngeal, stool and urine samples were collected and tested for the presence of 38 different potential aetiological causes of fever.
RESULTS
Samples from 741 children were analysed, the protocol was successful in determining a probable aetiological cause of acute fever in 544 (73.61%) cases. Respiratory viruses were the most frequently identified pathogens, present in the nasopharynx samples of 435 (58.86%) cases, followed by bacteria detected in 167 (22.60%) samples. Despite presenting negative mRDTs, P. falciparum was identified in samples of 24 (3.25%) patients.
CONCLUSIONS
This research provides a description of the aetiological causes of NMAFI in West African context. Evidence of viral infections were more commonly found than bacteria or parasites.
With growing use of parasitological tests to detect malaria and decreasing incidence of the disease in Africa; it becomes necessary to increase the understanding of causes of non-malaria acute febrile illness (NMAFI) towards providing appropriate case management. This research investigates causes of NMAFI in pediatric out-patients in rural Guinea-Bissau.
METHODS
Children 0–5 years presenting acute fever (≥38°) or history of fever, negative malaria rapid diagnostic test (mRDT) and no signs of specific disease were recruited at the out-patient clinic of 3 health facilities in Bafatá province during 54 consecutive weeks (dry and rainy season). Medical history was recorded and blood, nasopharyngeal, stool and urine samples were collected and tested for the presence of 38 different potential aetiological causes of fever.
RESULTS
Samples from 741 children were analysed, the protocol was successful in determining a probable aetiological cause of acute fever in 544 (73.61%) cases. Respiratory viruses were the most frequently identified pathogens, present in the nasopharynx samples of 435 (58.86%) cases, followed by bacteria detected in 167 (22.60%) samples. Despite presenting negative mRDTs, P. falciparum was identified in samples of 24 (3.25%) patients.
CONCLUSIONS
This research provides a description of the aetiological causes of NMAFI in West African context. Evidence of viral infections were more commonly found than bacteria or parasites.
Conference Material > Poster
Moreto-Planas L, Mahajan R, Sagrado MJ, Flevaud L, Gallo J, et al.
MSF Scientific Day International 2023. 7 June 2023; DOI:10.57740/0xmg-7p42
Journal Article > Short ReportFull Text
Emerg Infect Dis. 1 January 2023; Volume 29 (Issue 1); 154-159.; DOI:10.3201/eid2901.220775
Molina-de la Fuente I, Benito MJS, Flevaud L, Ousley J, Pasquale HA, et al.
Emerg Infect Dis. 1 January 2023; Volume 29 (Issue 1); 154-159.; DOI:10.3201/eid2901.220775
Pfhrp2 and pfhrp3 gene deletions threaten the use of Plasmodium falciparum malaria rapid diagnostic tests globally. In South Sudan, deletion frequencies were 15.6% for pfhrp2, 20.0% for pfhrp3, and 7.5% for double deletions. Deletions were approximately twice as prevalent in monoclonal infections than in polyclonal infections.
Journal Article > ResearchAbstract Only
J Vector Borne Dis. 1 July 2021; DOI:10.4103/0972-9062.321747
Mahajan R, Nair MM, Saldanha AM, Harshana A, de Lima Pereira A, et al.
J Vector Borne Dis. 1 July 2021; DOI:10.4103/0972-9062.321747
BACKGROUND AND OBJECTIVES
There is limited evidence regarding the accuracy of dengue rapid diagnostic kits despite their extensive use in India. We evaluated the performance of four immunochromatographic Rapid Diagnostic Test (RDTs) kits: Multisure dengue Ab/Ag rapid test (MP biomedicals; MP), Dengucheck combo (Zephyr Biomedicals; ZB), SD bioline dengue duo (Alere; SD) and Dengue day 1 test (J Mitra; JM).
METHODS
This is a laboratory-based diagnostic evaluation study. Rapid tests results were compared to reference non-structural (NS1) antigen or immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) results of 241 dengue-positive samples and 247 dengue-negative samples. Sensitivity and specificity of NS1 and IgM components of each RDT were calculated separately and in combination (either NS1 or IgM positive) against reference standard ELISA.
RESULTS
A total of 238, 226, 208, and 146 reference NS1 ELISA samples were tested with MP, ZB, SD, and JM tests, respectively. In comparison to the NS1 ELISA reference tests, the NS1 component of MP, ZB, SD, and JM RDTs demonstrated a sensitivity of 71.8%, 85.1%, 77.2% and 80.9% respectively and specificity of 90.1%, 92.8%, 96.1 %, and 93.6%, respectively. In comparison to the IgM ELISA reference test, the IgM component of RDTs showed a sensitivity of 40.0%, 50.3%, 47.3% and 20.0% respectively and specificity of 92.4%, 88.6%, 96.5%, and 92.2% respectively. Combining NS1 antigen and IgM antibody results led to sensitivities of 87.5%, 82.9%, 93.8% and 91.7% respectively, and specificities of 75.3%, 73.9%, 76.5%, and 80.0% respectively.
INTERPRETATION & CONCLUSIONS
Though specificities were acceptable, the sensitivities of each test were markedly lower than manufacturers' claims. These results also support the added value of combined antigen-and antibody-based RDTs for the diagnosis of acute dengue.
There is limited evidence regarding the accuracy of dengue rapid diagnostic kits despite their extensive use in India. We evaluated the performance of four immunochromatographic Rapid Diagnostic Test (RDTs) kits: Multisure dengue Ab/Ag rapid test (MP biomedicals; MP), Dengucheck combo (Zephyr Biomedicals; ZB), SD bioline dengue duo (Alere; SD) and Dengue day 1 test (J Mitra; JM).
METHODS
This is a laboratory-based diagnostic evaluation study. Rapid tests results were compared to reference non-structural (NS1) antigen or immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) results of 241 dengue-positive samples and 247 dengue-negative samples. Sensitivity and specificity of NS1 and IgM components of each RDT were calculated separately and in combination (either NS1 or IgM positive) against reference standard ELISA.
RESULTS
A total of 238, 226, 208, and 146 reference NS1 ELISA samples were tested with MP, ZB, SD, and JM tests, respectively. In comparison to the NS1 ELISA reference tests, the NS1 component of MP, ZB, SD, and JM RDTs demonstrated a sensitivity of 71.8%, 85.1%, 77.2% and 80.9% respectively and specificity of 90.1%, 92.8%, 96.1 %, and 93.6%, respectively. In comparison to the IgM ELISA reference test, the IgM component of RDTs showed a sensitivity of 40.0%, 50.3%, 47.3% and 20.0% respectively and specificity of 92.4%, 88.6%, 96.5%, and 92.2% respectively. Combining NS1 antigen and IgM antibody results led to sensitivities of 87.5%, 82.9%, 93.8% and 91.7% respectively, and specificities of 75.3%, 73.9%, 76.5%, and 80.0% respectively.
INTERPRETATION & CONCLUSIONS
Though specificities were acceptable, the sensitivities of each test were markedly lower than manufacturers' claims. These results also support the added value of combined antigen-and antibody-based RDTs for the diagnosis of acute dengue.
Journal Article > CommentaryFull Text
PLoS Negl Trop Dis. 4 June 2015; Volume 9 (Issue 6); e0003697.; DOI:10.1371/journal.pntd.0003697
Porras AI, Yadon ZE, Altcheh J, Britto C, Chaves GC, et al.
PLoS Negl Trop Dis. 4 June 2015; Volume 9 (Issue 6); e0003697.; DOI:10.1371/journal.pntd.0003697
Journal Article > ResearchFull Text
PLoS Negl Trop Dis. 7 July 2009; Volume 3 (Issue 7); DOI:10.1371/journal.pntd.0000488
Yun O, Lima MA, Ellman T, Chambi W, Castillo S, et al.
PLoS Negl Trop Dis. 7 July 2009; Volume 3 (Issue 7); DOI:10.1371/journal.pntd.0000488
BACKGROUND:
Chagas disease (American trypanosomiasis) is a zoonotic or anthropozoonotic disease caused by the parasite Trypanosoma cruzi. Predominantly affecting populations in poor areas of Latin America, medical care for this neglected disease is often lacking. Médecins Sans Frontières/Doctors Without Borders (MSF) has provided diagnostic and treatment services for Chagas disease since 1999. This report describes 10 years of field experience in four MSF programs in Honduras, Guatemala, and Bolivia, focusing on feasibility protocols, safety of drug therapy, and treatment effectiveness.
METHODOLOGY:
From 1999 to 2008, MSF provided free diagnosis, etiological treatment, and follow-up care for patients <18 years of age seropositive for T. cruzi in Yoro, Honduras (1999-2002); Olopa, Guatemala (2003-2006); Entre Ríos, Bolivia (2002-2006); and Sucre, Bolivia (2005-2008). Essential program components guaranteeing feasibility of implementation were information, education, and communication (IEC) at the community and family level; vector control; health staff training; screening and diagnosis; treatment and compliance, including family-based strategies for early detection of adverse events; and logistics. Chagas disease diagnosis was confirmed by testing blood samples using two different diagnostic tests. T. cruzi-positive patients were treated with benznidazole as first-line treatment, with appropriate counseling, consent, and active participation from parents or guardians for daily administration of the drug, early detection of adverse events, and treatment withdrawal, when necessary. Weekly follow-up was conducted, with adverse events recorded to assess drug safety. Evaluations of serological conversion were carried out to measure treatment effectiveness. Vector control, entomological surveillance, and health education activities were carried out in all projects with close interaction with national and regional programs.
RESULTS:
Total numbers of children and adolescents tested for T. cruzi in Yoro, Olopa, Entre Ríos, and Sucre were 24,471, 8,927, 7,613, and 19,400, respectively. Of these, 232 (0.9%), 124 (1.4%), 1,475 (19.4%), and 1,145 (5.9%) patients, respectively, were diagnosed as seropositive. Patients were treated with benznidazole, and early findings of seroconversion varied widely between the Central and South American programs: 87.1% and 58.1% at 18 months post-treatment in Yoro and Olopa, respectively; 5.4% by up to 60 months in Entre Ríos; and 0% at an average of 18 months in Sucre. Benznidazole-related adverse events were observed in 50.2% and 50.8% of all patients treated in Yoro and Olopa, respectively, and 25.6% and 37.9% of patients in Entre Ríos and Sucre, respectively. Most adverse events were mild and manageable. No deaths occurred in the treatment population.
CONCLUSIONS:
These results demonstrate the feasibility of implementing Chagas disease diagnosis and treatment programs in resource-limited settings, including remote rural areas, while addressing the limitations associated with drug-related adverse events. The variability in apparent treatment effectiveness may reflect differences in patient and parasite populations, and illustrates the limitations of current treatments and measures of efficacy. New treatments with improved safety profiles, pediatric formulations of existing and new drugs, and a faster, reliable test of cure are all urgently needed.
Chagas disease (American trypanosomiasis) is a zoonotic or anthropozoonotic disease caused by the parasite Trypanosoma cruzi. Predominantly affecting populations in poor areas of Latin America, medical care for this neglected disease is often lacking. Médecins Sans Frontières/Doctors Without Borders (MSF) has provided diagnostic and treatment services for Chagas disease since 1999. This report describes 10 years of field experience in four MSF programs in Honduras, Guatemala, and Bolivia, focusing on feasibility protocols, safety of drug therapy, and treatment effectiveness.
METHODOLOGY:
From 1999 to 2008, MSF provided free diagnosis, etiological treatment, and follow-up care for patients <18 years of age seropositive for T. cruzi in Yoro, Honduras (1999-2002); Olopa, Guatemala (2003-2006); Entre Ríos, Bolivia (2002-2006); and Sucre, Bolivia (2005-2008). Essential program components guaranteeing feasibility of implementation were information, education, and communication (IEC) at the community and family level; vector control; health staff training; screening and diagnosis; treatment and compliance, including family-based strategies for early detection of adverse events; and logistics. Chagas disease diagnosis was confirmed by testing blood samples using two different diagnostic tests. T. cruzi-positive patients were treated with benznidazole as first-line treatment, with appropriate counseling, consent, and active participation from parents or guardians for daily administration of the drug, early detection of adverse events, and treatment withdrawal, when necessary. Weekly follow-up was conducted, with adverse events recorded to assess drug safety. Evaluations of serological conversion were carried out to measure treatment effectiveness. Vector control, entomological surveillance, and health education activities were carried out in all projects with close interaction with national and regional programs.
RESULTS:
Total numbers of children and adolescents tested for T. cruzi in Yoro, Olopa, Entre Ríos, and Sucre were 24,471, 8,927, 7,613, and 19,400, respectively. Of these, 232 (0.9%), 124 (1.4%), 1,475 (19.4%), and 1,145 (5.9%) patients, respectively, were diagnosed as seropositive. Patients were treated with benznidazole, and early findings of seroconversion varied widely between the Central and South American programs: 87.1% and 58.1% at 18 months post-treatment in Yoro and Olopa, respectively; 5.4% by up to 60 months in Entre Ríos; and 0% at an average of 18 months in Sucre. Benznidazole-related adverse events were observed in 50.2% and 50.8% of all patients treated in Yoro and Olopa, respectively, and 25.6% and 37.9% of patients in Entre Ríos and Sucre, respectively. Most adverse events were mild and manageable. No deaths occurred in the treatment population.
CONCLUSIONS:
These results demonstrate the feasibility of implementing Chagas disease diagnosis and treatment programs in resource-limited settings, including remote rural areas, while addressing the limitations associated with drug-related adverse events. The variability in apparent treatment effectiveness may reflect differences in patient and parasite populations, and illustrates the limitations of current treatments and measures of efficacy. New treatments with improved safety profiles, pediatric formulations of existing and new drugs, and a faster, reliable test of cure are all urgently needed.
Journal Article > ResearchFull Text
Antimicrob Agents Chemother. 3 December 2018; Volume 63 (Issue 2); DOI:10.1128/AAC.01191-18
Parrado R, Ramirez JC, de la Barra A, Alonso-Vega C, Juiz N, et al.
Antimicrob Agents Chemother. 3 December 2018; Volume 63 (Issue 2); DOI:10.1128/AAC.01191-18
This work evaluated a serial blood sampling procedure to enhance the sensitivity of duplex real-time PCR (qPCR) for baseline detection and quantification of parasitic loads and post-treatment identification of failure in the context of clinical trials for treatment of chronic Chagas disease, namely DNDi-CH-E1224-001 (NCT01489228) and MSF-DNDi PCR sampling optimization study (NCT01678599). Patients from Cochabamba (N= 294), Tarija (N= 257), and Aiquile (N= 220) were enrolled. Three serial blood samples were collected at each time-point and qPCR triplicates were tested per sample. The first two samples were collected during the same day and the third one seven days later.A patient was considered PCR positive if at least one qPCR replicate was detectable. Cumulative results of multiple samples and qPCR replicates enhanced the proportion of pre-treatment sample positivity from 54.8 to 76.2%, 59.5 to 77.8%, and 73.5 to 90.2% in Cochabamba, Tarija, and Aiquile cohorts, respectively. This strategy increased the detection of treatment failure from 72.9 to 91.7%, 77.8 to 88.9%, and 42.9 to 69.1% for E1224 low, short, and high dosage regimens, respectively; and from 4.6 to 15.9% and 9.5 to 32.1% for the benznidazole arm in the DNDi-CH-E1224-001 and MSF-DNDi studies, respectively. The addition of the third blood sample and third qPCR replicate in patients with non-detectable PCR results in the first two samples, gave a small, non-statistically significant improvement in qPCR positivity. No change in clinical sensitivity was seen with a blood volume increase from 5 to 10 ml. The monitoring of patients treated with placebo in the DNDi-CH-E1224-001 trial revealed fluctuations in parasitic loads and occasional non-detectable results. In conclusion, serial sampling strategy enhanced PCR sensitivity to detecting treatment failure during follow-up and has the potential for improving recruitment capacity in Chagas disease trials, which require an initial positive qPCR result for patient admission.
Journal Article > CommentaryFull Text
PLoS Negl Trop Dis. 25 May 2010; Volume 4 (Issue 5); DOI:10.1371/journal.pntd.0000720
Yun O, Priotto G, Tong J, Flevaud L, Chappuis F
PLoS Negl Trop Dis. 25 May 2010; Volume 4 (Issue 5); DOI:10.1371/journal.pntd.0000720
Journal Article > Short ReportFull Text
Emerg Infect Dis. 1 February 2010; Volume 16; DOI:10.3201/eid1602.090967
Chappuis F, Lima MA, Flevaud L, Ritmeijer KKD
Emerg Infect Dis. 1 February 2010; Volume 16; DOI:10.3201/eid1602.090967