Fasting blood glucose in a Ghanaian adult is causally affected by malaria parasite load: a mechanistic case study using convergent cross mapping

Anti-Inflammatory Effects of Helminth-Derived Products: Potential Applications and Challenges in Diabetes Mellitus Management

The global rise in diabetes mellitus (DM), particularly type 2 diabetes (T2D), has become a major public health challenge. According to the "hygiene hypothesis", helminth infections may offer therapeutic benefits for DM. These infections are known to modulate immune responses, reduce inflammation, and improve insulin sensitivity. However, they also carry risks, such as malnutrition, anemia, and intestinal obstruction. Importantly, helminth excretory/secretory products, which include small molecules and proteins, have shown therapeutic potential in treating various inflammatory diseases with minimal side effects. This review explores the anti-inflammatory properties of helminth derivatives and their potential to alleviate chronic inflammation in both type 1 diabetes and T2D, highlighting their promise as future drug candidates. Additionally, it discusses the possible applications of these derivatives in DM management and the challenges involved in translating these findings into clinical practice.

Forecasting malaria dynamics based on causal relations between control interventions, climatic factors, and disease incidence in western Kenya

Background

Malaria remains one of the deadliest diseases worldwide, especially among young children in sub-Saharan Africa. Predictive models are necessary for effective planning and resource allocation; however, statistical models suffer from association pitfalls. In this study, we used empirical dynamic modelling (EDM) to investigate causal links between climatic factors and intervention coverage with malaria for short-term forecasting.

Methods

Based on data spanning the period from 2008 to 2022, we used convergent cross-mapping (CCM) to identify suitable lags for climatic drivers and investigate their effects, interaction strength, and suitability ranges on malaria incidence. Monthly malaria cases were collected at St. Elizabeth Lwak Mission Hospital. Intervention coverage and population movement data were obtained from household surveys in Asembo, western Kenya. Daytime land surface temperature (LSTD), rainfall, relative humidity (RH), wind speed, solar radiation, crop cover, and surface water coverage were extracted from remote sensing sources. Short-term forecasting of malaria incidence was performed using state-space reconstruction.

Results

We observed causal links between climatic drivers, bed net use, and malaria incidence. LSTD lagged over the previous month; rainfall and RH lagged over the previous two months; and wind speed in the current month had the highest predictive skills. Increases in LSTD, wind speed, and bed net use negatively affected incidence, while increases in rainfall and humidity had positive effects. Interaction strengths were more pronounced at temperature, rainfall, RH, wind speed, and bed net coverage ranges of 30-35°C, 30-120 mm, 67-80%, 0.5-0.7 m/s, and above 90%, respectively. Temperature and rainfall exceeding 35°C and 180 mm, respectively, had a greater negative effect. We also observed good short-term predictive performance using the multivariable forecasting model (Pearson correlation coefficient = 0.85, root mean square error = 0.15).

Conclusions

Our findings demonstrate the utility of CCM in establishing causal linkages between malaria incidence and both climatic and non-climatic drivers. By identifying these causal links and suitability ranges, we provide valuable information for modelling the impact of future climate scenarios.

Malaria parasitaemia and its impact on biological parameters among children <16 years old attending the Nkwen District Hospital, Cameroon

Introduction

Malaria remains a major public health problem in children in endemic areas. This study aimed to determine its prevalence, intensity, and assess how biological parameters like RBC count, haemoglobin, haematocrit, glycaemia, platelet count and WBC count vary with respect to parasitaemia in children <16 years attending the Nkwen District Hospital, northwest Cameroon.

Materials and Methods

The study was a hospital-based cross-sectional study conducted between March-May 2023. Structured, closed-ended questionnaires were administered to obtain information. Patients' temperature was measured using an infrared forehead digital thermometer. Malaria was diagnosed by RDT and positive samples Giemsa-stained for parasitaemia. Full blood count was performed using a haemolyser and glycaemia measured using a glucometer.

Results

In total, 321 children were examined. Overall prevalence of malaria (all P. falciparum) was 22.7% (73/321), with 24.7% (18/73), 34.2% (25/73) and 41.1% (30/73) having low, moderate and high parasitaemias, respectively. Overall GMPD was 2.670.8±179.9/μL; children aged 6-10 years were hit hardest (5.377.7 ± 3.2/μL). Malaria-positive children had significantly lower RBC count, Hb concentration, Hct, blood sugar, WBC and platelet counts (p<0.05) compared to those that were negative. Among positive children, RBC count, Hct, Hb, lymphocyte and platelet count each showed a significant (p<0.05) decrease while total WBC and granulocyte count each showed a significant (p<0.05) increase with increasing levels of parasitaemia.

Conclusions

Changes in biological parameters during malaria are sensitive but poor specific indicators of malaria because they may overlap with symptoms of other infections. More attention should be given to children aged 6-10 years during strategic planning and design of malaria control programmes.

Assessing the daily natural history of asymptomatic Plasmodium infections in adults and older children in Katakwi, Uganda: a longitudinal cohort study

BACKGROUND

Low-density asymptomatic Plasmodium infections are prevalent in endemic areas, but little is known about their natural history. The trajectories of these infections and their propensity to fluctuate to undetectable densities can affect detection in clinical trials and field studies. We aimed to classify the natural history of these infections in a high transmission area over 29 days.

METHODS

In this longitudinal cohort study, we enrolled healthy, malaria-asymptomatic, afebrile, adults (age 18-59 years) and older children (age 8-17 years) in Katakwi District, Uganda, who were negative for Plasmodium infection on rapid diagnostic tests. Participants were instructed to self-collect one dried blood spot (DBS) per day for a maximum of 29 days. We excluded people if they were pregnant or taking antimalarials. During weekly clinic visits, staff collected a DBS and a 4 mL sample of venous blood. We analysed DBSs by Plasmodium 18S rRNA quantitative RT-PCR (qRT-PCR). We classified DBS by infection type as negative, P falciparum, non-P falciparum, or mixed. We plotted infection type over time for each participant and categorised trajectories as negative, new, cleared, chronic, or indeterminate infections. To estimate the effect of single timepoint sampling, we calculated the daily prevalence for each study day and estimated the number of infections that would have been detected in our population if sampling frequency was reduced.

FINDINGS

Between April 9 and May 20, 2021, 3577 DBSs were collected by 128 (40 male adults, 60 female adults, 12 male children, and 16 female children) study participants. 2287 (64%) DBSs were categorised as negative, 751 (21%) as positive for P falciparum, 507 (14%) as positive for non-P falciparum, and 32 (1%) as mixed infections. Daily Plasmodium prevalence in the population ranged from 45·3% (95% CI 36·6-54·1) at baseline to 30·3% (21·9-38·6) on day 24. 37 (95%) of 39 P falciparum and 35 (85%) of 41 non-P falciparum infections would have been detected with every other day sampling, whereas, with weekly sampling, 35 (90%) P falciparum infections and 31 (76%) non-P falciparum infections would have been detected.

INTERPRETATION

Parasite dynamics and species are highly variable among low-density asymptomatic Plasmodium infections. Sampling every other day or every 3 days detected a similar proportion of infections as daily sampling, whereas testing once per week or even less frequently could misclassify up to a third of the infections. Even using highly sensitive diagnostics, single timepoint testing might misclassify the true infection status of an individual.

FUNDING

US National Institutes of Health and Bill and Melinda Gates Foundation.

Plasmodium vivax Malaria in Duffy-Positive Patients in Rwanda

Plasmodium vivax is the second-most common malaria pathogen globally, but is considered very rare in the predominantly Duffy-negative sub-Saharan African population. In 259 malaria patients from highland southern Rwanda, we assessed Plasmodium species and Duffy blood group status by polymerase chain reaction (PCR). Plasmodium falciparum, P. vivax, Plasmodium malariae, and Plasmodium ovale were seen in 90.7%, 8.1%, 11.6%, and 5.0%, respectively. Plasmodium vivax occurred more frequently as a monoinfection than in combination with P. falciparum. All P. vivax-infected individuals showed heterozygous Duffy positivity, whereas this was the case for only 3.1% of patients with P. falciparum monoinfection and malaria-negative control subjects (P < 0.01). Based on PCR diagnosis, P. vivax is not rare in southern Rwanda. All episodes of P. vivax were observed in heterozygous Duffy-positive patients, whereas elsewhere in Africa, P. vivax is also reported in Duffy-negative individuals. Refined mapping of Plasmodium species is required to establish control and elimination strategies including all malaria species.

Temperature and nutrients drive eco-phenotypic dynamics in a microbial food web

Anthropogenic increases in temperature and nutrient loads will likely impact food web structure and stability. Although their independent effects have been reasonably well studied, their joint effects-particularly on coupled ecological and phenotypic dynamics-remain poorly understood. Here we experimentally manipulated temperature and nutrient levels in microbial food webs and used time-series analysis to quantify the strength of reciprocal effects between ecological and phenotypic dynamics across trophic levels. We found that (1) joint-often interactive-effects of temperature and nutrients on ecological dynamics are more common at higher trophic levels, (2) temperature and nutrients interact to shift the relative strength of top-down versus bottom-up control, and (3) rapid phenotypic change mediates observed ecological responses to changes in temperature and nutrients. Our results uncover how feedback between ecological and phenotypic dynamics mediate food web responses to environmental change. This suggests important but previously unknown ways that temperature and nutrients might jointly control the rapid eco-phenotypic feedback that determine food web dynamics in a changing world.