The American Society of Tropical Medicine & Hygiene (ASTMH) Annual Meeting is an international forum for the exchange of scientific and clinical advances in tropical medicine, hygiene and global health. The scientific content this year is 53% microbe focused, 15% clinically focused, 13% vector focused, 13% globally focused, and 6% intervention focused.
MSF and Epicentre are presenting on access and other challenges for children with visceral and cutaneous leishmaniasis, hurdles in malaria diagnostic testing, and ensuring equitable access to healthcare in conversations about financial sustainability.
This collection features research authored by the presenters and other topics highlighted at ASTMH.
BACKGROUND
Visceral leishmaniasis (VL) is an important public health problem, which mainly affects the poor rural dwelling communities in Low- and Middle-Income Countries. However, little is known about the health and economic burdens of this disease in East Africa, including Ethiopia. The aim of this study was to assess the household level economic burden of VL among affected communities in Tigray, Northern Ethiopia.
METHODS
Between April and August 2020, a cross-sectional household survey was conducted on 96 patients who had been treated for VL within 12 months prior to the survey, in six districts of Tigray. Data on households’ health seeking behavior, direct and indirect costs and coping strategies were collected using a structured questionnaire and the responses were analyzed using SPSS software.
RESULTS
Most (82%) of the patients surveyed were males and the majority (74%) of them were between 16 and 30 years of age. The education level of participants was very low: over 33% had not received any form of education; 48% of patients were farmers dependent on subsistence agriculture and about 32% were daily laborers. Just under half of household families (46%) resided in “poor houses” with structures made from entirely local materials. Forty-one percent of patients from the surveyed households had traveled 48 to 72 kilometers to reach VL treatment hospitals. The median total household cost for one VL episode was estimated to be US$ 214. This is equated to 18% of the mean total annual household income or 72.5% of annual per capita income of the study population. More than 80% of the households surveyed incurred catastrophic costs of VL, where this is defined as exceeding 10% of annual household income. The median delay between the onset of symptoms and arrival at a care provider hospital was 37 days; once the patient arrived at hospital, the median delay during diagnosis was 3 days. Direct and indirect costs represented 44% and 56% of the total costs incurred, respectively. To cope with VL treatment costs, 43% of the households used more than one coping strategy: 48% took out loans, 43% sold livestock and 31% of households mobilized cash savings.
CONCLUSIONS
VL in Tigray is concentrated among young males with low educational background and mostly engaged in subsistence economic activities. Despite the free diagnostic and treatment provisions that were available at public hospitals at the time of the study, our work shows that the household economic burden of the disease had significant impact among VL-affected communities in Tigray. Initiating community awareness towards prevention, early treatment seeking and decentralization of VL treatment centers are strongly recommended. In addition, we recommend efforts to reduce household treatment costs through transport and food provisions for patients (and their accompanying carers where possible) or through cash reimbursement for patients who complete treatment at public hospitals, in order to reduce the barriers to seeking treatment for this life-threatening disease.
Lassa fever is a viral haemorrhagic fever with few options for diagnosis and treatment; it is also under-researched with knowledge gaps on its epidemiology. A point-of-care bedside test diagnosing Lassa fever, adhering to REASSURED criteria, is not currently available but is urgently needed in west African regions with high Lassa fever burden. We aimed to assess the validity and feasibility of a rapid diagnostic test (RDT) to confirm Lassa fever in people in Nigeria.
METHODS
We estimated the diagnostic performance of the ReLASV Pan-Lassa RDT (Zalgen Labs, Frederick, MD, USA) as a research-use-only test, compared to RT-PCR as a reference standard, in 217 participants at a federal tertiary hospital in Abakaliki, Nigeria. We recruited participants between Feb 17, 2022, and April 17, 2023. The RDT was performed using capillary blood at the patient bedside and using plasma at the laboratory. The performance of the test, based on REASSURED criteria, was assessed for user friendliness, rapidity and robustness, sensitivity, and specificity.
FINDINGS
Participants were aged between 0 and 85 years, with a median age of 33·0 years (IQR 22·0-44·3), and 24 participants were younger than 18 years. 107 (50%) participants were women and 109 (50%) were men; one participant had missing sex data. Although the specificity of the Pan-Lassa RDT was high (>90%), sensitivity at bedside using capillary blood was estimated as 4% (95% CI 1-14) at 15 min and 10% (3-22) at 25 min, far below the target of 90%. The laboratory-based RDT using plasma showed better sensitivity (46% [32-61] at 15 min and 50% [36-64] at 25 min) but did not reach the target sensitivity. Among the 52 PCR-positive participants with Lassa fever, positive RDT results were associated with lower cycle threshold values (glycoprotein precursor [GPC] gene mean 30·3 [SD 4·3], Large [L] gene mean 32·3 [3·7] vs GPC gene mean 24·5 [3·9], L gene mean 28·0 [3·6]). Personnel conducting the bedside test procedure reported being hindered by the inconvenient use of full personal protective equipment and long waiting procedures before a result could be read.
INTERPRETATION
The Pan-Lassa RDT is not currently recommended as a diagnostic or screening tool for suspected Lassa fever cases. Marked improvement in sensitivity and user friendliness is needed for the RDT to be adopted clinically. There remains an urgent need for better Lassa fever diagnostics to promote safety of in-hospital care and better disease outcomes in low-resource settings.
Robust diagnostic tools and surveillance are crucial for malaria control and elimination efforts. Malaria caused by neglected Plasmodium parasites is often underestimated due to the lack of rapid diagnostic tools that can accurately detect these species. While nucleic-acid amplification technologies stand out as the most sensitive methods for detecting and confirming Plasmodium species, their implementation in resource-constrained settings poses significant challenges. Here, we present a Pan Plasmodium recombinase polymerase amplification lateral flow (RPA–LF) assay, capable of detecting all six human infecting Plasmodium species in low resource settings. The Pan Plasmodium RPA-LF assay successfully detected low density clinical infections with a preliminary limit of detection between 10–100 fg/µl for P. falciparum. When combined with crude nucleic acid extraction, the assay can serve as a point-of-need tool for molecular xenomonitoring. This utility was demonstrated by screening laboratory-reared Anopheles stephensi mosquitoes fed with Plasmodium-infected blood, as well as field samples of An. funestus s.l. and An. gambiae s.l. collected from central Africa. Overall, our proof-of-concept Pan Plasmodium diagnostic tool has the potential to be applied for clinical and xenomonitoring field surveillance, and after further evaluation, could become an essential tool to assist malaria control and elimination.
Visceral leishmaniasis (VL) is a parasitic disease with an estimated 30 000 new cases occurring annually. There is an observed variation in the efficacy of the current first-line therapies across different regions. Such heterogeneity could be a function of host, parasite and drug factors. An individual participant data meta-analysis (IPD-MA) is planned to explore the determinants of treatment outcomes.
METHODS AND ANALYSIS
The Infectious Diseases Data Observatory (IDDO) VL living systematic review (IDDO VL LSR) library is an open-access resource of all published therapeutic studies in VL since 1980. For this current review, the search includes all clinical trials published between 1 January 1980 and 2 May 2021. Studies indexed in the IDDO VL LSR library were screened for eligibility for inclusion in this IPD-MA. Corresponding authors and principal investigators of the studies meeting the eligibility criteria for inclusion were invited to be part of the collaborative IPD-MA. Authors agreeing to participate in this collaborative research were requested to share the IPD using the IDDO VL data platform. The IDDO VL data platform currently holds data sets from clinical trials standardised to a common data format and provides a unique opportunity to identify host, parasite and drug determinants of treatment outcomes. Multivariable regression models will be constructed to identify determinants of therapeutic outcomes using generalised linear mixed-effects models accounting for within-study site clustering.
ETHICS AND DISSEMINATION
This IPD-MA meets the criteria for waiver of ethical review as defined by the Oxford Tropical Research Ethics Committee (OxTREC) granted to IDDO, as the research consists of secondary analysis of existing anonymised data (Exempt granted on 29 March 2023, OxTREC REF: IDDO) Ethics approval was granted by the ICMR-Rajendra Memorial Research Institute of Medical Sciences ethics committee (Letter no: RMRI/EC/30/2022) on 04-07-2022. The results of this IPD-MA will be disseminated at conferences, IDDO website and any peer-reviewed publications. All publications will be open source. Findings of this research will be critically important for the control programmes at regional/global levels, policy makers and groups developing new VL treatments.
Noma is a rapidly spreading infection of the oral cavity which mainly affects young children. Without early treatment, it can have a high mortality rate. Simple gingivitis is a warning sign for noma, and acute necrotizing gingivitis is the first stage of noma. The epidemiology of noma is not well understood. We aimed to understand the prevalence of all stages of noma in hospitalised children.
METHODS
We conducted a prospective observational study from 1st June to 24th October 2021, enrolling patients aged 0 to 12 years who were admitted to the Anka General Hospital, Zamfara, northwest Nigeria. Consenting parents/ guardians of participants were interviewed at admission. Participants had anthropometric and oral exams at admission and discharge.
FINDINGS
Of the 2346 patients, 58 (2.5%) were diagnosed with simple gingivitis and six (n = 0.3%) with acute necrotizing gingivitis upon admission. Of those admitted to the Inpatient Therapeutic Feeding Centre (ITFC), 3.4% (n = 37, CI 2.5–4.7%) were diagnosed with simple gingivitis upon admission compared to 1.7% of those not admitted to the ITFC (n = 21, CI 1.1–2.6%) (p = 0.008). Risk factors identified for having simple gingivitis include being aged over two years (2 to 6 yrs old, odds ratio (OR) 3.4, CI 1.77–6.5; 7 to 12 yrs OR 5.0, CI 1.7–14.6; p = <0.001), being admitted to the ITFC (OR 2.1; CI 1.22–3.62) and having oral health issues in the three months prior to the assessment (OR 18.75; CI 10.65, 33.01). All (n = 4/4) those aged six months to five years acute necrotizing gingivitis had chronic malnutrition.
CONCLUSION
Our study showed a small proportion of children admitted to the Anka General Hospital had simple or acute necrotizing gingivitis. Hospital admission with malnutrition was a risk factor for both simple and acute necrotizing gingivitis The lack of access to and uptake of oral health care indicates a strong need for oral exams to be included in routine health services. This provision could improve the oral status of the population and decrease the chance of patients developing noma.
Rapid diagnostic tests (RDT) for malaria are the primary tool for malaria diagnosis in sub-Saharan Africa but the utility of the most commonly used histidine-rich protein 2 (HRP2) antigen-based tests is limited in high transmission settings due to the long duration of positivity after successful malaria treatment. HRP2 tests are also threatened by the emergence of Plasmodium that do not carry pfhrp2 or pfhrp 3 genes. Plasmodium lactate dehydrogenase (pLDH)-based tests are promising alternatives, but less available. This study assessed the performances of HRP2 and pLDH(pan) tests under field conditions.
METHODS
The study performed a prospective facility-based diagnostic evaluation of two malaria RDTs in Aweil, South Sudan, during the high transmission season. Capillary blood by fingerprick was collected from 800 children under 15 years of age with fever and no signs of severity. SD Bioline HRP2 and CareStart pLDH(pan) RDTs were performed in parallel, thick and thin smears for microscopy were examined, and dried blood was used for PCR testing.
RESULTS
Using microscopy as the gold standard, the sensitivity of both tests was estimated at > 99%, but the specificity of each was lower: 55.0% for the pLDH test and 61.7% for the HRP2 test. When using PCR as the gold standard, the sensitivity of both tests was lower than the values assessed using microscopy (97.0% for pLDH and 96.5% for HRP2), but the specificity increased (65.1% for pLDH and 72.9% for HRP2). Performance was similar across different production lots, sex, and age. Specificity of both the pLDH and HRP2 tests was significantly lower in children who reported taking a therapeutic course of anti-malarials in the 2 months prior to enrollment. The prevalence of pfhrp2/3 deletions in the study population was 0.6%.
CONCLUSIONS
The low specificity of the pLDH RDT in this setting confirms previous results and suggests a problem with this specific test. The prevalence of pfhrp2/3 deletions in the study area warrants continued monitoring and underscores the relevance of assessing deletion prevalence nationally. Improved malaria RDTs for high-transmission environments are needed.
Reports on the occurrence and outcome of Visceral Leishmaniasis (VL) in pregnant women is rare in published literature. The occurrence of VL in pregnancy is not systematically captured and cases are rarely followed-up to detect consequences of infection and treatment on the mother and foetus.
METHODS
A review of all published literature was undertaken to identify cases of VL infections among pregnant women by searching the following database: Ovid MEDLINE; Ovid Embase; Cochrane Database of Systematic Reviews; Cochrane Central Register of Controlled Trials; World Health Organization Global Index Medicus: LILACS (Americas); IMSEAR (South-East Asia); IMEMR (Eastern Mediterranean); WPRIM (Western Pacific); ClinicalTrials.gov; and the WHO International Clinical Trials Registry Platform. Selection criteria included any clinical reports describing the disease in pregnancy or vertical transmission of the disease in humans. Articles meeting pre-specified inclusion criteria and non-primary research articles such as textbook, chapters, letters, retrospective case description, or reports of accidental inclusion in trials were also considered.
RESULTS
The systematic literature search identified 272 unique articles of which 54 records were included in this review; a further 18 records were identified from additional search of the references of the included studies or from personal communication leading to a total of 72 records (71 case reports/case series; 1 retrospective cohort study; 1926-2020) describing 451 cases of VL in pregnant women. The disease was detected during pregnancy in 398 (88.2%), retrospectively confirmed after giving birth in 52 (11.5%), and the time of identification was not clear in 1 (0.2%). Of the 398 mothers whose infection was identified during pregnancy, 346 (86.9%) received a treatment, 3 (0.8%) were untreated, and the treatment status was not clear in the remaining 49 (12.3%). Of 346 mothers, Liposomal amphotericin B (L-AmB) was administered in 202 (58.4%) and pentavalent antimony (PA) in 93 (26.9%). Outcomes were reported in 176 mothers treated with L-AmB with 4 (2.3%) reports of maternal deaths, 5 (2.8%) miscarriages, and 2 (1.1%) foetal death/stillbirth. For PA, outcomes were reported in 88 mothers of whom 4 (4.5%) died, 24 (27.3%) had spontaneous abortion, 2 (2.3%) had miscarriages. A total of 26 cases of confirmed, probable or suspected cases of vertical transmission were identified with a median detection time of 6 months (range: 0-18 months).
CONCLUSIONS
Outcomes of VL treatment during pregnancy are rarely reported and under-researched. The reported articles were mainly case reports and case series and the reported information was often incomplete. From the studies identified, it is difficult to derive a generalisable information on outcomes for mothers and babies, although reported data favours the usage of liposomal amphotericin B for the treatment of VL in pregnant women.
In 2010, WHO recommended the use of new short-course treatment regimens in kala-azar elimination efforts for the Indian subcontinent. Although phase 3 studies have shown excellent results, there remains a lack of evidence on a wider treatment population and the safety and effectiveness of these regimens under field conditions.
METHODS
This was an open label, prospective, non-randomized, non-comparative, multi-centric trial conducted within public health facilities in two highly endemic districts and a specialist referral centre in Bihar, India. Three treatment regimens were tested: single dose AmBisome (SDA), concomitant miltefosine and paromomycin (Milt+PM), and concomitant AmBisome and miltefosine (AmB+Milt). Patients with complicated disease or significant co-morbidities were treated in the SDA arm. Sample sizes were set at a minimum of 300 per arm, taking into account inter-site variation and an estimated failure risk of 5% with 5% precision. Outcomes of drug effectiveness and safety were measured at 6 months. The trial was prospectively registered with the Clinical Trials Registry India: CTRI/2012/08/002891.
RESULTS
Out of 1,761 patients recruited, 50.6% (n = 891) received SDA, 20.3% (n = 358) AmB+Milt and 29.1% (n = 512) Milt+PM. In the ITT analysis, the final cure rates were SDA 91.4% (95% CI 89.3-93.1), AmB+Milt 88.8% (95% CI 85.1-91.9) and Milt+PM 96.9% (95% CI 95.0-98.2). In the complete case analysis, cure rates were SDA 95.5% (95% CI 93.9-96.8), AmB+Milt 95.5% (95% CI 92.7-97.5) and Milt+PM 99.6% (95% CI 98.6-99.9). All three regimens were safe, with 5 severe adverse events in the SDA arm, two of which were considered to be drug related.
CONCLUSION
All regimens showed acceptable outcomes and safety profiles in a range of patients under field conditions. Phase IV field-based studies, although extremely rare for neglected tropical diseases, are good practice and an important step in validating the results of more restrictive hospital-based studies before widespread implementation, and in this case contributed to national level policy change in India.
