Finger-prick Blood Research Articles

Haematological point of care testing for clozapine monitoring

BackgroundClozapine treatment requires regular full blood counts (FBC) because of the risk of agranulocytosis. Traditionally, FBCs use venous blood samples but the need for frequent venepuncture adversely affects adherence. We investigated the utility of a point of care testing (POCT) finger prick method for clozapine patients. MethodPatients being treated with clozapine, who were having a venous blood sample taken for haematological monitoring, also provided a fingerprick capillary blood sample. The PixCell HemoScreen® POCT analyser was used to test both the capillary and venous samples, and the venous sample was also tested using a standard laboratory method. ResultsWe completed FBCs on 226 patients. We found strong correlations between the results from the standard laboratory venous method and the POCT capillary and venous assays for WBC (R = 0.96 & R = 0.99), neutrophils (R = 0.96 & R = 0.97) and eosinophils (R = 0.94 & R = 0.94). Compared with the standard laboratory venous blood method, mean biases for capillary blood POCT method were −0.56 × 109/L for WBC, −0.39 × 109/L for neutrophils, and −0.01 × 109/L for eosinophils. Mean biases for venous blood POCT method were −0.004 × 109/L for WBC, −0.28 × 109/L for neutrophils, and 0.01 × 109/L for eosinophils. Of the 226 patients tested, 10 (4.4%) had levels below clozapine monitoring thresholds (WBC <3.5 × 109/L and Neutrophils <1.5 × 109/L) by capillary blood, and 4 (1.8%) by venous blood by POCT. The standard laboratory method showed 3 of these to be sub-threshold. All cases of neutropenia were identified by capillary and venous POCT. ConclusionThe PixCell HemoScreen® POCT analyser provided results that were comparable with those from a standard venous blood laboratory method for WBC, neutrophil and eosinophil counts. The availability of an accurate capillary monitoring method may result in increased clozapine uptake and better clozapine adherence.

Seroprevalence of visceral leishmaniasis and its associated factors among asymptomatic pastoral community of Dire District, Borena zone, Oromia Region, Ethiopia.

Visceral leishmaniasis (VL) is a vector-borne protozoan neglected tropical disease. In some parts of Ethiopia, it is a public health problem and its main causative agent is the Leishmania donovani complex. The objective of the study was to determine the seroprevalence of VL and factors associated among the asymptomatic pastoral community of Dire District, Borena Zone, Oromia Region, Ethiopia. A community-based study was conducted among 432 pastoralist communities from June to July 2021. A systematic random sampling method was used to select households. Pretested structured questionnaires and face-to-face interviews were used to collect data. A single finger-prick blood sample was collected and tested for Leishmania donovani complex using an immune-chromatographic test (rk39-ICT). A logistic regression model was used to assess factors associated with VL infection and a p-value of < 0.05 was considered statistically significant. A total of 432 study participants were included (their mean age was 26.69) and 218 (50.5%) were females. The overall seroprevalence of VL was 33/432(7.6%) (95%CI: 5.32-15.60). Sero-prevalence was significantly associated with high family size (>5) (adjusted odds ratios (AOR) = 5.134; 95% CI: 2.032-9.748), sleeping or/and staying under acacia tree (AOR = 2.984; 95%CI = 1.074-8.288), presence of cracked house walls (AOR = 1.801; 95%CI: 1.026-4.926), presence of termite hills (AOR = 1.938; 95%CL: 1.002-7.050), availability of water points (AOR = 3.893; 95%CI: 1.034-7.426) and presence of domestic animals (AOR = 2.124; 95% CI: 2.341-5.108). It is recommended that community awareness on the transmission and prevention methods of Leishmania donovani complex and taking appropriate interventions on the identified factors play a greater role to prevent and control infection in the area. Further investigation is also needed to characterize the pathogens and risk factors and tackle the problem.

Malaria among under-five children in rural communities of Al-Mahweet governorate, Yemen

BackgroundMalaria burden among under-five children living in endemic areas of Yemen is largely unknown due to the lack of community-based studies. Therefore, this study determined the prevalence and risk factors associated with falciparum malaria among under-five children in rural communities of Al-Mahweet governorate, Yemen.MethodsThis community-based, cross-sectional study recruited 400 under-five children from two rural districts of Al-Mahweet governorate in December 2019. Demographic characteristics (gender, age, education and occupation of the child’s parents, and household size) and risk factors associated with malaria were collected through interviews with children’s caregivers using a structured questionnaire. Finger-prick blood was screened for Plasmodium falciparum and non-falciparum species using rapid diagnostic tests (RDTs), and duplicate Giemsa-stained thick and thin blood films were examined for malaria parasites. The density of asexual P. falciparum stages was also estimated. Data were then analysed, and the agreement between the results of thick-film microscopy and RDTs for diagnosing falciparum malaria was assessed using the kappa index. Statistical significance was set at a P-value of < 0.05.ResultsPlasmodium falciparum was prevalent among 9.8% (95% CI 7.0–13.1) of under-five children in the rural communities of Al-Mahweet, with a median asexual parasite density of 763 ± 2606 parasites/μl of blood (range: 132–4280) and low-to-moderate parasitaemia levels. Approximately one-third of microscopy-confirmed cases were gametocyte carriers. Multivariable logistic regression analysis confirmed that age of three years or older (AOR = 5.6, 95% CI 1.6–19.8; P = 0.007), not sleeping under a mosquito net the previous night of the survey (AOR = 8.0, 95% CI 2.4–27.4; P = 0.001), sleeping outdoors at night (AOR = 4.4, 95% CI 2.0–10.0; P < 0.001), and absence of indoor residual spraying (IRS) during the last year (AOR = 4.2, 95% CI 1.9–9.4; P < 0.001) were the independent predictors of falciparum malaria among under-five children in the rural communities of Al-Mahweet. The observed percentage agreement between thick-film microscopy and RDTs was 98.5%, with a very good agreement (k-index = 0.9) between the two methods for falciparum malaria diagnosis that was statistically significant.ConclusionApproximately one in ten under-five children in rural communities of Al-Mahweet is infected with P. falciparum based on microscopy and RDTs. Age of three years or older, not sleeping under mosquito nets, sleeping outdoors at night and absence of IRS can independently predict falciparum malaria among them. The very good agreement between thick-film microscopy and RDTs for diagnosing falciparum malaria in children supports the usefulness of using RDTs in such resource-limited rural communities.

Diagnostic challenges in monitoring and evaluating annual ivermectin (Mectizan®) treatment intervention strategy to determine onchocerciasis elimination status

Ability to accurately detect an active infection depends largely on the high accuracy (sensitivity and specificity) of a diagnostic test. There is no single diagnostic tool that meets the criteria of been simple, measurable, accurate, repeatable and timely (SMART). Combining the screening and confirmation tests have been relied upon in determining the true epidemiological situation of ongoing ivermectin or Mectizan® treatment intervention strategy. Antibody detection assays have been evaluated as screening tools using various formats like different types of agglutination protocol, enzyme linked immunosorbent assays (ELISA) and nucleic acid amplification tests (NAAT). Despite these developments, presence of any stage of the parasite antigen, microfilaria (fourth larva, L4) and macrofilaria (adult worm) confirms active infection. The standard microscopic examination of skin snips for emerged microfilaria obtained with a scleral biopsy punch is capable of spreading blood viral diseases. The sensitivity of the test has decreased following post-treatment with ivermectin and surveillance for recrudescence is inevitable. On one hand, the time preceding when parasite materials liberated as against when detectable immune responses were invoked decreases the sensitivity of serological tests. The DNA molecular based tests with the attendant complexity of protocol remained a technical barrier that has been surmounted with the development of loop- mediated isothermal amplification (LAMP). This technique amplifies DNA with high specificity, sensitivity and rapidity under isothermal conditions. It will serve as alternative definitive diagnostic test to skin microfilaria detection. A combination of LAMP with IgG4 antibodies against O. volvulus 16 kiloDalton (Ov16) antigen is used as a rapid qualitative test of human finger-prick blood, serum and plasma now widely applied in disease endemic countries. Also, diethyl carbamazine (DEC) patch skin test for popular eruption indicative of positive infection attracted further re-evaluation as non-invasive screening tool devoid of skin biopsy and blood sample collection.

The COVID-19 Schools Infection Survey in England: Protocol and Participation Profile for a Prospective Observational Cohort Study.

One of the most debated questions in the COVID-19 pandemic has been the role of schools in SARS-CoV-2 transmission. The COVID-19 Schools Infection Survey (SIS) aims to provide much-needed evidence addressing this issue. We present the study protocol and participation profile for the SIS study, aimed at assessing the role of schools in SARS-CoV-2 infection and transmission within school settings, and investigating how transmission within and from schools could be mitigated through the implementation of school COVID-19 control measures. SIS was a multisite, prospective, observational cohort study conducted in a stratified random sample of primary and secondary schools in selected local authorities in England. A total of 6 biobehavioral surveys were planned among participating students and staff during the 2020-2021 academic year, between November 2020 and July 2021. Key measurements were SARS-CoV-2 virus prevalence, assessed by nasal swab polymerase chain reaction; anti-SARS-CoV-2 (nucleocapsid protein) antibody prevalence and conversion, assessed in finger-prick blood for staff and oral fluid for students; student and staff school attendance rates; feasibility and acceptability of school-level implementation of SARS-CoV-2 control measures; and investigation of selected school outbreaks. The study was approved by the United Kingdom Health Security Agency Research Support and Governance Office (NR0237) and London School of Hygiene &amp; Tropical Medicine Ethics Review Committee (reference 22657). Data collection and laboratory analyses were completed by September 2021. A total of 22,585 individuals-1891 staff and 4654 students from 59 primary schools and 5852 staff and 10,188 students from 97 secondary schools-participated in at least one survey. Across all survey rounds, staff and student participation rates were 45.2% and 16.4%, respectively, in primary schools and 30% and 15.2%, respectively, in secondary schools. Although primary student participation increased over time, and secondary student participation remained reasonably consistent, staff participation declined across rounds, especially for secondary school staff (3165/7583, 41.7% in round 1 and 2290/10,374, 22.1% in round 6). Although staff participation overall was generally reflective of the eligible staff population, student participation was higher in schools with low absenteeism, a lower proportion of students eligible for free school meals, and from schools in the least deprived locations (in primary schools, 446/4654, 9.6% of participating students were from schools in the least deprived quintile compared with 1262/22,225, 5.7% of eligible students). We outline the study design, methods, and participation, and reflect on the strengths of the SIS study as well as the practical challenges encountered and the strategies implemented to address these challenges. The SIS study, by measuring current and incident infection over time, alongside the implementation of control measures in schools across a range of settings in England, aims to inform national guidance and public health policy for educational settings. RR1-10.2196/34075.

Prevalence of HIV/AIDS Infection among Sexually Active Women in Ethiopia: Further Analysis of 2016 EDHS.

The issue of HIV/AIDS is prevalent around the world and in Ethiopia as well. The aim of this study was to determine the prevalence and risk factors of HIV/AIDS infection among sexually active women in Ethiopia. For this study, data were obtained from the Ethiopia Demographic and Health Survey conducted in 2016. This study contains 11,729 women who have had at least one episode of sexual intercourse in their lifetime. Interviewers for voluntary HIV testing collected finger-prick blood specimens from women who agreed to be tested for HIV. Based on factors at the individual and community levels, a multilevel logistic regression model was used. The study found that 2% of 11,729 sexually active women tested positive for HIV from all regions who received voluntary counseling and testing. The intraclass correlation coefficient findings showed that 32.844% of HIV/AIDS transmission among sexually active women was the result of community-level factors. Variables at the individual level were women of age 16-24 (AOR = 0.18; 95% CI: 0.11-0.29), women of age 25-34 (AOR = 0.733; 95% CI: 0.55-0.98), women with primary education level (AOR = 1.8; 95% CI: 1.23-2.57), more than one sexual accomplice (AOR = 1.33; 95% CI: 0.613-2.87), and women's age at first sexual intercourse between 25 and 34 (AOR = 0.57, 95% CI: 0.301, 1.06); these were the most significant determinants of HIV/AIDS infection. According to community-level factors, there was a lower HIV prevalence rate among rural women (AOR = 0.22; 95 percent CI: 0.13-0.36), and women in the Gambela region (AOR = 4.1; 95 percent CI: 1.99-8.34) also had higher HIV prevalence rates. The prevalence of HIV infection among sexually active women varies by region, with urban women more likely to contract the virus. Women who had more than one regular sexual partner and had their first sexual encounter at a younger age are at an increased risk of contracting HIV/AIDS. According to the study, the government should focus more support on high-risk clusters, mainly in urban areas, as well as on regions with high rates of HIV/AIDS infection.

Closing the gap — development of an analytical methodology using volumetric absorptive microsampling of finger prick blood followed by LC-HRMS/MS for adherence monitoring of antihypertensive drugs

Volumetric absorptive microsampling (VAMS), an emerging microsampling technique, is a promising tool for adherence monitoring. This study focused on development of an analytical methodology to improve VAMS-based strategies for adherence assessment by analyzing angiotensin-converting-enzyme (ACE) inhibitors, loop diuretics, a potassium-sparing diuretic, and a thiazide diuretic. Development included sample preparation, chromatographic conditions, mass spectrometry settings, validation, and demonstrating proof of concept. Quantification of analytes, by name furosemide, hydrochlorothiazide, lisinopril, torasemide, and the active metabolites, canrenone, enalaprilat, and ramiprilat in finger prick blood (FPB), was validated based on international guidelines. Selectivity, carryover, and within/between-run accuracy and precision were in accordance with the recommendations. The matrix effect was evaluated at three different hematocrit levels (HT: 20%, 40%, 60%) and the coefficients of variation did not exceed 15%. Dilution integrity (1:10 and 1:20) was given for all analytes except lisinopril, yet for lisinopril, the therapeutic range was already covered by the calibration range. Long-term stability in VAMS tips was tested for 2 weeks at 24 °C in the dark and revealed no degradation of analytes. The proof of concept was performed by analyzing 35 intakes of ACE-inhibitors and diuretics in 18 VAMS and matched plasma samples. Hereby, determined concentration in FPB and plasma cannot be used interchangeably, and thus specific reference ranges for whole blood must be established. Nevertheless, the VAMS-based strategy was shown to be suitable for assessing adherence of all classes of antihypertensive drugs used in the guidelines to manage hypertension.Graphical abstract

ODP226 MONITORING THE INCIDENCES OF ALLERGIC CONTACT DERMATITIS AND OTHER SKIN REACTIONS ASSOCIATED WITH CONTINUOUS GLUCOSE MONITORING SYSTEMS

Abstract The CDC reports 1 in 10 Americans have Diabetes and that number only continues to rise each year. Diabetes is a lifestyle altering condition that requires those diagnosed to monitor their blood sugar daily. Traditionally finger prick blood draws were the only method to do this and it put many at increased risk for infection and reduced digit sensation, until Continuous Glucose Monitoring (CGM) was later developed. CGM's are unique because they can attach to any part of the body and upload data to smart devices. Unfortunately, CGM's brought about new issues for diabetics. As CGM use increased, as did incidences of allergic and irritant contact dermatitis (ACD &amp; ICD), preventing many from continuing its use. The purpose of this Literature Review is to assess current articles focused on ACD, ICD, and other skin conditions related to CGM use and consider how diabetics can prevent and treat these side effects to safely resume CGM use. Presentation: No date and time listed

Investigating transmission of SARS-CoV-2 using novel face mask sampling: a protocol for an observational prospective study of index cases and their contacts in a congregate setting

IntroductionThis study aims to measure how transmission of SARS-CoV-2 occurs in communities and to identify conditions that lend to increased transmission focusing on congregate situations. We will measure SARS-CoV-2 in...

Is finger prick blood collection using Mitra® volumetric absorptive microsampling (VAMS) device a viable alternative to venous for testosterone, cortisol, 25 hydroxyvitamin D and bone resorption marker [beta]-CTX measurements?

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Electrochemical Carbamazepine Aptasensor for Therapeutic Drug Monitoring at the Point of Care.

Monitoring the anti-epileptic drug carbamazepine (CBZ) is crucial for proper dosing, optimizing a patient's clinical outcome, and managing their medication regimen. Due to its narrow therapeutic window and concentration-related toxicity, CBZ is prescribed and monitored in a highly personalized manner. We report an electrochemical conformation-changing aptasensor with two assay formats: a 30 min assay for routine monitoring and a 5 min assay for rapid emergency testing. To enable "sample-to-answer" testing, a de novo CBZ aptamer (K d < 12 nM) with conformational switching due to a G-quadruplex motif was labeled with methylene blue and immobilized on a gold electrode. The electrode fabrication and detection conditions were optimized using electrochemical techniques and visualized by atomic force microscopy (AFM). The aptasensor performance, including reproducibility, stability, and interference, was characterized using electrochemical impedance spectroscopy and voltammetry techniques. The aptasensor exhibited a wide dynamic range in buffer (10 nM to 100 μM) with limits of detection of 1.25 and 1.82 nM for the 5 and 30 min assays, respectively. The clinical applicability is demonstrated by detecting CBZ in finger prick blood samples (<50 μL). The proposed assays provide a promising method to enable point-of-care monitoring for timely personalized CBZ dosing.

Continuous Glucose Monitoring for the Diagnosis of Gestational Diabetes Mellitus: A Pilot Study.

Background Gestational diabetes mellitus (GDM) is diabetes first diagnosed in pregnancy. GDM, together with its short- and long-term negative outcomes, is increasing in incidence all over the world. The current diagnostic method for GDM, the oral glucose tolerance test (OGTT), is dated and has been reported as inconvenient for women as well as poorly reproducible and reliable. Aims We aimed at assessing the acceptability, feasibility, and accuracy of continuous glucose monitoring (CGM) as a diagnostic test for GDM and explore its correlation with the OGTT and risk factors for GDM. Methods In this prospective cohort study, pregnant women due for or having completed OGTT underwent CGM for seven days, performing daily finger-prick blood glucose levels before completing an acceptability questionnaire. Data on GDM risk factors and CGM variability were analyzed and compared with OGTT results. Results Seventy-three women completed CGM (40 GDM, 33 normal glucose tolerances); 34 concurrently underwent OGTT. CGM was acceptable and generally well-tolerated, with skin irritation/itchiness the only adverse event (11 mild, one severe). CGM and OGTT strongly correlated for fasting glucose values (r = 0.86, p < 0.05) only. Triangulating GDM risk factors, OGTT results and CGM variability parameters with the application of machine learning highlighted the possibility of unmasking false positive (11 showed low CGM variability and demographic risks but positive OGTT) and false-negative OGTT diagnoses (1 showed high CGM variability and demographic risks but negative OGTT). Conclusions CGM was well-tolerated, showing poorer glycaemic control in GDM, and revealing potential misdiagnosis of the OGTT when combined with GDM risk factors. Future research is needed to determine cut-off values for CGM-defined and OGTT-independent screening criteria for GDM.

Clinical malaria incidence and health seeking pattern in geographically heterogeneous landscape of western Kenya

BackgroundMalaria remains a public health problem in Kenya despite sustained interventions deployed by the government. One of the major impediments to effective malaria control is a lack of accurate diagnosis and effective treatment. This study was conducted to assess clinical malaria incidence and treatment seeking profiles of febrile cases in western Kenya.MethodsActive case detection of malaria was carried out in three eco-epidemiologically distinct zones topologically characterized as lakeshore, hillside, and highland plateau in Kisumu County, western Kenya, from March 2020 to March 2021. Community Health Volunteers (CHVs) conducted biweekly visits to residents in their households to interview and examine for febrile illness. A febrile case was defined as an individual having fever (axillary temperature ≥ 37.5 °C) during examination or complaints of fever and other nonspecific malaria related symptoms 1–2 days before examination. Prior to the biweekly malaria testing by the CHVs, the participants' treatment seeking methods were based on their behaviors in response to febrile illness. In suspected malaria cases, finger-prick blood samples were taken and tested for malaria parasites with ultra-sensitive Alere® malaria rapid diagnostic tests (RDT) and subjected to real-time polymerase chain reaction (RT-PCR) for quality control examination.ResultsOf the total 5838 residents interviewed, 2205 residents had high temperature or reported febrile illness in the previous two days before the visit. Clinical malaria incidence (cases/1000people/month) was highest in the lakeshore zone (24.3), followed by the hillside (18.7) and the highland plateau zone (10.3). Clinical malaria incidence showed significant difference across gender (χ2 = 7.57; df = 2, p = 0.0227) and age group (χ2 = 58.34; df = 4, p < 0.0001). Treatment seeking patterns of malaria febrile cases showed significant difference with doing nothing (48.7%) and purchasing antimalarials from drug shops (38.1%) being the most common health-seeking pattern among the 2205 febrile residents (χ2 = 21.875; df = 4, p < 0.0001). Caregivers of 802 school-aged children aged 5–14 years with fever primarily sought treatment from drug shops (28.9%) and public hospitals (14.0%), with significant lower proportions of children receiving treatment from traditional medication (2.9%) and private hospital (4.4%) (p < 0.0001). There was no significant difference in care givers' treatment seeking patterns for feverish children under the age of five (p = 0.086). Residents with clinical malaria cases in the lakeshore and hillside zones sought treatment primarily from public hospitals (61.9%, 60/97) traditional medication (51.1%, 23/45) respectively (p < 0.0001). However, there was no significant difference in the treatment seeking patterns of highland plateau residents with clinical malaria (p = 0.431).The main factors associated with the decision to seek treatment were the travel distance to the health facility, the severity of the disease, confidence in the treatment, and affordability.ConclusionClinical malaria incidence remains highest in the Lakeshore (24.3cases/1000 people/month) despite high LLINs coverage (90%). The travel distance to the health facility, severity of disease and affordability were mainly associated with 80% of residents either self-medicating or doing nothing to alleviate their illness. The findings of this study suggest that the Ministry of Health should strengthen community case management of malaria by providing supportive supervision of community health volunteers to advocate for community awareness, early diagnosis, and treatment of malaria.

Non-Invasive Lactate Monitoring System Using Wearable Chipless Microwave Sensors With Enhanced Sensitivity and Zero Power Consumption.

Monitoring lactate levels is an established method for determining hyperlactatemia in critically ill patients and assessing aerobic fitness. It is a widely used gold-standard technique in both professional and serious amateur sports. Non-invasive real-time lactate monitoring offers significant advantages over the current technology of finger-prick blood sampling. Possible candidate technology for developing non-invasive real-time lactate monitoring should be highly sensitive, flexible, and capable of real-time monitoring of lactate levels in interstitial fluid or within specific working muscle groups depending on the type of sport. Herein we describe a planar, flexible, passive, chipless tag resonator that is electromagnetically coupled to a reader placed in proximity to the lactate sensor tag. The tag resonator is a thin metallic tracing that can be taped on the skin. The resonance frequency of the tag fluctuates proportionately with changing lactate concentrations in a solution mimicking human interstitial fluid with very high sensitivity. The spectrum of the tag is reflected in the spectrum of the reader, which is a planar microwave resonator designed at a different frequency. The reader could be embedded in a cellphone or an application-specific wearable device for data communication and processing. The tag can accurately and reproducibly measure lactate concentrations in the range of 1 to 10 mM, which is in the physiological range of lactate observed at rest and during intense physical activity. Furthermore, the chrematistics of this technology will allow monitoring of lactate in specific working muscle groups.

Influence of landscape heterogeneity on entomological and parasitological indices of malaria in Kisumu, Western Kenya

BackgroundIdentification and characterization of larval habitats, documentation of Anopheles spp. composition and abundance, and Plasmodium spp. infection burden are critical components of integrated vector management. The present study aimed to investigate the effect of landscape heterogeneity on entomological and parasitological indices of malaria in western Kenya.MethodsA cross-sectional entomological and parasitological survey was conducted along an altitudinal transect in three eco-epidemiological zones: lakeshore along the lakeside, hillside, and highland plateau during the wet and dry seasons in 2020 in Kisumu County, Kenya. Larval habitats for Anopheles mosquitoes were identified and characterized. Adult mosquitoes were sampled using pyrethrum spray catches (PSC). Finger prick blood samples were taken from residents and examined for malaria parasites by real-time PCR (RT-PCR).ResultsIncreased risk of Plasmodium falciparum infection was associated with residency in the lakeshore zone, school-age children, rainy season, and no ITNs (χ2 = 41.201, df = 9, P < 0.0001). Similarly, lakeshore zone and the rainy season significantly increased Anopheles spp. abundance. However, house structures such as wall type and whether the eave spaces were closed or open, as well as the use of ITNs, did not affect Anopheles spp. densities in the homes (χ2 = 38.695, df = 7, P < 0.0001). Anopheles funestus (41.8%) and An. arabiensis (29.1%) were the most abundant vectors in all zones. Sporozoite prevalence was 5.6% and 3.2% in the two species respectively. The lakeshore zone had the highest sporozoite prevalence (4.4%, 7/160) and inoculation rates (135.2 infective bites/person/year). High larval densities were significantly associated with lakeshore zone and hillside zones, animal hoof prints and tire truck larval habitats, wetland and pasture land, and the wet season. The larval habitat types differed significantly across the landscape zones and seasonality (χ2 = 1453.044, df = 298, P < 0.0001).ConclusionThe empirical evidence on the impact of landscape heterogeneity and seasonality on vector densities, parasite transmission, and Plasmodium infections in humans emphasizes the importance of tailoring specific adaptive environmental management interventions to specific landscape attributes to have a significant impact on transmission reduction.Graphical abstract

Asymptomatic and submicroscopic Plasmodium infections in an area before and during integrated vector control in Homa Bay, western Kenya

BackgroundLong-lasting insecticidal nets (LLINs) have been the primary vector control strategy until indoor residual spraying (IRS) was added in Homa Bay and Migori Counties in western Kenya. The objective of this study was to evaluate the impact of LLINs integrated with IRS on the prevalence of asymptomatic and submicroscopic Plasmodium infections in Homa Bay County.MethodsA two-stage cluster sampling procedure was employed to enroll study participants aged ≥ 6 months old. Four consecutive community cross-sectional surveys for Plasmodium infection were conducted in residents of Homa Bay county, Kenya. Prior to the start of the study, all study households received LLINs, which were distributed between June 2017 and March 2018. The first (February 2018) and second (June 2018) surveys were conducted before and after the first round of IRS (Feb–Mar 2018), while the third (February 2019) and fourth (June 2019) surveys were conducted before and after the second application of IRS (February–March 2019). Finger-prick blood samples were obtained to prepare thick and thin smears for microscopic determination and qPCR diagnosis of Plasmodium genus.ResultsPlasmodium spp. infection prevalence by microscopy was 18.5% (113/610) before IRS, 14.2% (105/737) and 3.3% (24/720) after the first round of IRS and 1.3% (11/849) after the second round of IRS (p < 0.0001). Submicroscopic (blood smear negative, qPCR positive) parasitaemia reduced from 18.9% (115/610) before IRS to 5.4% (46/849) after IRS (p < 0.0001). However, the proportion of PCR positive infections that were submicroscopic increased from 50.4% (115/228) to 80.7% (46/57) over the study period (p < 0.0001). Similarly, while the absolute number and proportions of microscopy positives which were asymptomatic decreased from 12% (73/610) to 1.2% (9/849) (p < 0.0001), the relative proportion increased. Geometric mean density of P. falciparum parasitaemia decreased over the 2-year study period (p < 0.0001).ConclusionsThese data suggest that two annual rounds of IRS integrated with LLINs significantly reduced the prevalence of Plasmodium parasitaemia, while the proportion of asymptomatic and submicroscopic infections increased. To reduce cryptic P. falciparum transmission and improve malaria control, strategies aimed at reducing the number of asymptomatic and submicroscopic infections should be considered.

P435 Evaluation of remote triazole capillary blood testing to facilitate remote therapeutic drug monitoring (TDM): A validation study

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PMBackgroundThe advent of COVID-19 has meant that patients with chronic diseases needed to shield, however, investigations were needed to guide continual management of their disease. Remote monitoring options were evaluated to ensure the standard of care is not compromised.Purpose and HypothesisThe aim was to validate remote (return-posted) capillary triazole blood testing and evaluate the potential role of remote TDM in chronic antifungal therapy.Materials and MethodsA single-center prospective cross-sectional study of remote finger prick capillary blood testing compared with gold standard venesection was performed. Remote finger prick capillary blood testing was validated compared to local standard venesection using comparative statistical analysis Comparative statistical analysis: Paired t-test, correlation and Bland-Altman were used to determine if there was agreement or association between the sampling methods.ResultsA total of 66 patients receiving triazole therapy were recruited and 57 pooled pairs of remote capillary and venous triazole concentrations and metabolites were prospectively analyzed, with the rest of the blood samples not being analyzed due to insufficient sample, hemolysis, or undetectable triazole level of <0.2 mg/l. There was a significant difference in the comparison of the two methods of sampling with paired t-test at P <.0001. Bland-Altman analysis yielded wide bias (−49.07%) and wide limits of agreement (−85.5% to −12.64%). On average capillary triazole, concentrations were 37% lower than venous concentrations (Fig. 1). There was however a very strong correlation between capillary and venous tests (Pearson's correlation coefficient r = 0.9219, P <.0001, Fig. 2).ConclusionsRemote capillary triazole sampling does not appear interchangeable with venous sampling, but being strongly correlated and on average 2/3rd of the venous value, could be a predictor of venous triazole level, or be useful for intra-patient longitudinal monitoring. When incorporated into an outpatient clinical pathway it can improve shared decision-making and patient experience. Further research is required to determine appropriate target reference ranges if the new lower capillary levels can be used routinely, especially in the climate of COVID-19 where social distancing measures limit patient access to hospitals and clinics for routine investigations.

A portable smartphone-based hemoglobin point-of-care testing platform for accurate anemia diagnostics

Anemia affects over 2 billion people worldwide, with the heaviest burden borne by women and children. At present, anemia is diagnosed by measuring hemoglobin (Hb) levels, which must be done in hospitals or commercial laboratories by skilled operators. In this work, we report a portable, affordable ($3), easy-to-operate (1 min) and accurate smartphone-based Hb analyzer (SHbA) that uses a drop of finger-pricked blood for anemia point-of-care test (POCT) applications. POCT of Hb was achieved using a smartphone ambient light sensor (ALS) to accurately measure the absorbance of colorimetric Hb biochemical analysis reagents in a microcuvette, as well as an Android-based application for results analysis. SHbA validation results agreed well with those reported by a hematology analyzer, and the SHbA has an anemia diagnosis sensitivity of 95.4% and specificity of 96.3% for venous blood (n = 360) and a sensitivity of 96.39% and specificity of 95.58% for fingertip blood (n = 475). In addition, SHbA exhibits excellent performance in the diagnosis and treatment guidance of anemia high-risk populations, including tumor chemotherapy patients (n = 424), pregnant women (n = 214) and thalassemia patients (n = 208). Importantly, volunteer self-testing results (n = 20) indicate that SHbA can be used for home-based anemia diagnosis and monitoring. SHbA has the advantages of high sensitivity and specificity while being cheap and easy to operate, making it widely applicable for the diagnosis and treatment of anemia, especially for high-risk patients in areas with poor medical resources.

Urogenital schistosomiasis transmission, malaria and anemia among school-age children in Northern Ghana

BackgroundIn sub-Saharan Africa, co-morbidity with malaria, schistosomiasis, and soil transmitted helminths (STH) is common among young children. The current study investigated malaria, urinary schistosomiasis and their co-infection and anemia among school-age children in an endemic community, Nakolo in the Kassena-Nankana East District of northern Ghana. MethodsA cross-sectional survey of 336 school-age children, 5–16 years was undertaken. Urine samples were examined for Schistosoma haematobium ova using microscopy. Finger prick blood samples were examined for Plasmodium parasites using microscopy and haemoglobin concentration measured with HemoCue Hb301 photometer. ResultsThe mean age was 10.52 (Standard deviation: ±2.27; range: 5–16 years), of which 50.6% (170/336) were males. The overall prevalence of urinary schistosomiasis and Plasmodium (P.) falciparum was 12.8% (43/336) and 37.8% (127/336), respectively with 6.0% (20/336) coinfection. Participants with only P. falciparum infection had 17.8% (19/107) of moderate anemia whilst 21.7% (5/23) of children infected with only S. haematobium had moderate anemia and 4.3% (1/23) had severe anemia. 5.0 % (1/20) of moderate anemia was observed in concurrent infections of P. falciparum and S. haematobium. Use of open water bodies was associated with increased risk of S. haematobium infection (OR = 1.21; 95% CI = [1.06–1.39]; p = 0.001), with females being at reduced risk (OR = 0.93; 95%CI = [0.87–0.99]; p = 0.005). Absence of self-reported haematuria had 0.81 times reduced odds of S. haematobium infection (OR = 0.81; 95%CI = [0.74–0.87]; p < 0.001). ConclusionThis study has revealed that urinary schistosomiasis remains prevalent in Kassena-Nankana East district and suggests that urinary schistosomiasis may contribute to moderate anemia among school-age children as compared to asymptomatic malaria infection. These findings call for an evaluation of the annual mass drug administration of Praziquantel among in-school children to ascertain its impact on urinary schistosomiasis prevalence across the district.

Prevalence and diversity of Plasmodium species in pregnant women attending antenatal clinics in selected health centers of Kakamega County, Western Kenya

Malaria remains a major public health concern around the world with tropical and sub-tropical regions bearing the greatest brunt despite up-scaling of control strategies. Despite the provisioning of insecticidal nets to expectant women attending antenatal care facilities, Plasmodium infections was a recurrent problem in Kakamega County. We hypothesized that socioeconomic factors were risk factors for the high prevalence levels of asymptomatic Plasmodium infections (API) among pregnant women in the County. A prospective cohort of 304 asymptomatic pregnant women aged 18 years and older was identified to assess the association between patient characteristics and risk of API using a cross-sectional study design. The study was conducted across four representative antenatal clinics (ANC) in the region. A pre-structured and pre-tested questionnaire was used to obtain the socio-demographic characteristics, residence, and knowledge of malaria. The questionnaire was followed by a face-to-face interview. Each participant provided a fingerprick blood sample for a thick and thion blood smear for parasite studies at Masinde Muliro University Science and Technology. The slides were examined at ×100 oil immersion. Plasmodium and the developmental stages were checked, quantified, and recorded. The data were analyzed using SPSS ver 16. Differences in parasite densities for various parameters was assessed using Mann Whitney U and Kruskal Wallis non-parametric tests. Ordinary linear squares (OLS) regression was used to uncover any significant associations at 95% CI and p-value ≤ 0.05. The majority of the women had a post-primary education (75%), were married (60.9%), multigravidae (50%), in their second trimester (41.4%), residing in rural areas (62.2%), used ITNs (77%), and did not practice IRS (67.8%) as a malaria prevention method. Plasmodium species infection prevalence was (24.34%; 95% CI, 19.52–29.16) P. falciparum (82.4%; 95% CI 73.72–91.08) accounting for the majority of infections. The parity and gestation status of the pregnant women were found to have a significant association with API. This study showed that a significant number of women in Kakamega County attending ANCs were asymptomatic for Plasmodium malaria. We propose that malaria screening through microscopy and treatment should be incorporated into maternal health within the county.