Etiology of severe invasive infections in young infants in rural settings in sub-Saharan Africa.

BACKGROUND: Serious invasive infections in newborns are a major cause of death. Lack of data on etiological causes hampers progress towards reduction of mortality. This study aimed to identify pathogens responsible for such infections in young infants in sub-Saharan Africa and to describe their antibiotics resistance profile. METHODS: Between September 2016 and April 2018 we implemented an observational study in two rural sites in Burkina Faso and Tanzania enrolling young infants aged 0-59 days old with serious invasive infection. Blood samples underwent blood culture and molecular biology. RESULTS: In total 634 infants with clinical diagnosis of serious invasive infection were enrolled and 4.2% of the infants had a positive blood culture. The most frequent pathogens identified by blood culture were Klebsiella pneumonia and Staphylococcus aureus, followed by Escherichia coli. Gram-negative isolates were only partially susceptible to first line WHO recommended treatment for neonatal sepsis at community level. A total of 18.6% of the infants were PCR positive for at least one pathogen and Escherichia coli and Staphylococcus aureus were the most common bacteria detected. Among infants enrolled, 60/634 (9.5%) died. Positive blood culture but not positive PCR was associated with risk of death. For most deaths, no pathogen was identified either by blood culture or molecular testing, and hence a causal agent remained unclear. Mortality was associated with low body temperature, tachycardia, respiratory symptoms, convulsions, history of difficult feeding, movement only when stimulated or reduced level of consciousness, diarrhea and/or vomiting. CONCLUSION: While Klebsiella pneumonia and Staphylococcus aureus, as well as Escherichia coli were pathogens most frequently identified in infants with clinical suspicion of serious invasive infections, most cases remain without definite diagnosis, making more accurate diagnostic tools urgently needed. Antibiotics resistance to first line antibiotics is an increasing challenge even in rural Africa.

The outcome of a test-treat package versus routine outpatient care for Ghanaian children with fever: a pragmatic randomized control trial.

BACKGROUND: Over-diagnosis of malaria among African children results in mismanagement of non-malaria infections. Limited laboratory capacity makes it difficult to implement policies that recommend pre-treatment confirmation of infections so a new approach with a package for on-the-spot management of fevers was evaluated. METHODS: Febrile children presenting to outpatient clinic were randomized to receive either a 'test-treat' package (history with clinical examination; point-of-care tests; choice of artesunate-amodiaquine, co-amoxiclav and/or paracetamol) or routine outpatient care in a secondary health care facility in Kumasi, Ghana. A diagnosis of malaria, bacterial, viral or mixed malarial and bacterial infections was made using pre-defined criteria. Outcome was resolution of all symptoms including fever on day 7. RESULTS: The median age of the patients was 37.5 months (IQR: 19 to 66 months), with 56.7% being males. Compared to routine care the test-treat package resulted in less diagnoses of malaria, (37.2% vs 46.2%, p = 0.190) and mixed malaria and bacterial infections (14.0% vs 53.8%, p < 0.001) but more diagnoses of viral (33.1% vs 0.0%, p < 0.001) and bacterial infections only (15.7% vs 0.0%, p < 0.001). Less anti-malarials (51.2% vs 100.0%, p < 0.001) and antibiotics (29.7% vs 48.7%, p < 0.001), were prescribed in the test-treat group on completion of study, more test-treat package patients were clinically well (99.2% vs 80.7%, p < 0.001) and febrile (0.8% vs 10.1%, p = 0.001) and less were admitted for inpatient care (0.0% vs 8.4% p = 0.001) compared to the routine care group. CONCLUSION: Test-treat package improves the effectiveness of outpatient diagnosis and treatment of children with fever and reduces inappropriate prescribing of anti-malarials and antibiotics. The package provides clinicians with the option for immediate diagnosis and treatment of non-malaria fevers. The test-treat package now needs to be evaluated in other settings including primary health care facilities.

Evaluation of commercially available diagnostic tests for the detection of dengue virus NS1 antigen and anti-dengue virus IgM antibody.

Commercially available diagnostic test kits for detection of dengue virus (DENV) non-structural protein 1 (NS1) and anti-DENV IgM were evaluated for their sensitivity and specificity and other performance characteristics by a diagnostic laboratory network developed by World Health Organization (WHO), the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) and the Pediatric Dengue Vaccine Initiative (PDVI). Each network laboratory contributed characterized serum specimens for the panels used in the evaluation. Microplate enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic test (RDT formats) were represented by the kits. Each ELISA was evaluated by 2 laboratories and RDTs were evaluated by at least 3 laboratories. The reference tests for IgM anti-DENV were laboratory developed assays produced by the Armed Forces Research Institute for Medical Science (AFRIMS) and the Centers for Disease Control and Prevention (CDC), and the NS1 reference test was reverse transcriptase polymerase chain reaction (RT-PCR). Results were analyzed to determine sensitivity, specificity, inter-laboratory and inter-reader agreement, lot-to-lot variation and ease-of-use. NS1 ELISA sensitivity was 60-75% and specificity 71-80%; NS1 RDT sensitivity was 38-71% and specificity 76-80%; the IgM anti-DENV RDTs sensitivity was 30-96%, with a specificity of 86-92%, and IgM anti-DENV ELISA sensitivity was 96-98% and specificity 78-91%. NS1 tests were generally more sensitive in specimens from the acute phase of dengue and in primary DENV infection, whereas IgM anti-DENV tests were less sensitive in secondary DENV infections. The reproducibility of the NS1 RDTs ranged from 92-99% and the IgM anti-DENV RDTs from 88-94%.

Review of two decades of cholera diagnostics--how far have we really come?

BACKGROUND: Cholera, an ancient scourge, continues to inflict high rates of mortality today. The rising incidence of epidemics in areas of poor sanitation and crowding highlight the need for better epidemic prevention and early response. Such interventions require the availability of rapid and accurate diagnostic techniques to trigger timely response and mitigate the scale of the outbreak. The current gold standard of bacterial culture is inadequate for rapid diagnosis, highlighting the overarching neglect of field diagnostic needs. This paper was written to support the World Health Organisation's Global Task Force on Cholera Control mandated Cholera and diarrhoeal disease laboratory Network (CholdiNet) in devising a protocol for the validation of Rapid Diagnostic Tests (RDTs) for Vibrio cholerae. The status of diagnostic tools for Vibrio cholerae is assessed, describing products that have been commercialised over the last two decades and discussing their peer-reviewed evaluation. METHOD: Review of post-1990 peer-reviewed and grey literature on rapid diagnostic tests for Vibrio cholerae. RESULTS: Since 1990, twenty four diagnostic tests have been developed for the detection of Vibrio cholerae in human faecal samples. Fourteen of these have also been described in the literature, with rapid chromatographic-immuno assays (CIA) featuring strongly. Polymerase chain reaction (PCR) assays maintain the ability to detect the lowest amount of bacteria; however CIAs achieve both low detection thresholds and high sensitivity and specificity, making them possible candidates for use in field conditions. Field and laboratory studies were performed in a wide range of settings demonstrating variability in performance, however only a few of these studies were sufficiently stringent, highlighting five RDTs that showed promise in field conditions; COAT, IP cholera dipstick, SMART, IP dipstick and Medicos. In light of non-independent reporting, the authors would like to see these five products undergoing additional studies, with further technical improvements if needed and commercial production. The authors hope that public health use of such a RDT in limited-resource field conditions on stool samples may contribute to effective reduction in cholera epidemic spread.

Infectious diseases biobanking as a catalyst towards personalized medicine: Mycobacterium tuberculosis paradigm.

Research for biomarkers supporting personalized medicine in infectious diseases is needed, especially for tuberculosis in which the existing toolbox does not yet address the public health priorities. Biobanks are essential infrastructures in this effort by collecting, authenticating and preserving human and/or bacterial specimens. A broad range of specimens should be collected prior to, during and following treatment, with a comprehensive characterisation of the sample donors and the samples themselves to accommodate the most recent technological platforms in biomarker research. This review explains current state-of-the-field biobanking practices in tuberculosis and suggests technical and managerial improvements to ensure long-term preservation and optimal use of the specimens. Open-access and certified biobanks are an essential component of a strategy supporting the development of drugs and diagnostic tests for both public health and personalised medicine. Biobanks have a role to play in the interaction between these two - not always compatible - approaches.

Patient needs and point-of-care requirements for HIV load testing in resource-limited settings.

Medecins Sans Frontieres (MSF) is an international, independent medical nongovernmental organization. One way in which MSF acts to improve patient care is to assist in the identification and development of adapted and appropriate tools for use in resource-limited settings. One strategy to achieve this goal is through active collaborations with scientists and developers, to make some of the field needs known and to help define the medical strategy behind the implementation of new diagnostic tests. Tests used in the field need to be effective in often extreme conditions and must also deliver high-quality, reliable results that can be used in the local context. In this article, we discuss some patient and health care provider needs for human immunodeficiency virus (HIV) load measurement in resource-limited settings. This is just one of the areas in which effective, quality tools are desperately needed, not only by MSF and other international nongovernmental organizations, but also by many other health service providers. We hope that, by clearly defining the needs of patients in MSF clinics-as well as we can assess this-and by explaining why these tools are needed, how they should perform, and how their results can be integrated into a program, we will encourage the development of such tools and hasten their implementation in areas where they are so urgently needed.

Assessment of three new parasite lactate dehydrogenase (pan-pLDH) tests for diagnosis of uncomplicated malaria.

A study to assess the diagnostic capabilities of three parasite lactate dehydrogenase (pan-pLDH) tests, Vistapan), Carestart and Parabank), was conducted in Uganda. An HRP2 test, Paracheck-Pf), and a Giemsa-stained blood film were performed with the pLDH tests for outpatients with suspected malaria. In total, 460 subjects were recruited: 248 with positive blood films and 212 with negative blood films. Plasmodium falciparum was present in 95% of infections. Sensitivity above 90% was shown by two pLDH tests, Carestart (95.6%) and Vistapan (91.9%), and specificity above 90% by Parabank (94.3%) and Carestart (91.5%). Sensitivity decreased with low parasitaemia (chi(2) trend, P<0.001); however, all tests achieved sensitivity >90% with parasitaemia > or =100/microl. All tests had good inter-reader reliability (kappa>0.95). Two weeks after diagnosis, 4-10% of pLDH tests were still positive compared with 69.7% of the HRP2 tests. All tests had similar ease of use. In conclusion, two pLDH tests performed well in diagnosing P. falciparum malaria, and all pLDH tests became negative after treatment more quickly than the HRP2. Therefore the rapid test of choice for use with artemisinin-combination therapies in this area would be one of these new pLDH tests.

Neglected tests for neglected patients: alternative ways to develop diagnosis tools for use in resource-poor settings can, and do exist

It presents a commentary about alternatives ways to develop diagnostic tools for the infection diseases, neglected diseases, especially malaria, but the long list of diseases with no field-adapted diagnostic tools includes leishmaniasis, shigella, typhoid and bacterial meningitis. It approaches the needs and the Doctors without Borders’s action. Document in PDF format, required Acrobat Reader.