Where do nivicolous myxomycetes occur? – Modeling the potential worldwide distribution of Physarum albescens

Modelling of potential risk areas of pertussis cases in the Philippines using bioclimatic envelopes

OBJECTIVES

Pertussis remains a pressing public health concern in the Philippines despite being vaccine-preventable. The resurgence of the disease, driven by waning immunity, vaccine hesitancy and erratic outbreaks, underscores the need for innovative surveillance methods. Thus, this study intends to create a predictive model of potential risk areas for pertussis outbreaks in the Philippines using bioclimatic variables.

METHODS

This study employs the maximum entropy algorithm to predict pertussis risk areas in the Philippines based on 19 bioclimatic variables. The occurrence data of reported pertussis cases were obtained from two sources: the National Disaster Risk Reduction and Management Council, covering 30 March-11 June 2024, and the Weekly Epidemiological Surveillance Report, spanning 1 January-12 October 2024.

RESULTS

Key variables such as Mean Temperature of the Wettest Quarter (BIO8), Precipitation of the Wettest Quarter (BIO16) and Precipitation of the Driest Quarter (BIO17) were identified as significant predictors. Results revealed high-risk areas concentrated in northern Luzon, particularly Central Luzon (Region III), the major coastal areas of Ilocos (Region I), National Capital Region, MIMAROPA (Region IV-B), and an isolated area in Bicol (Region V). The model performance indicates excellent predictive accuracy (AUC = 0.972).

CONCLUSION

The findings highlight how climatic factors shape pertussis distribution through anthropogenic means (e.g., higher humidity increases the chances of acquiring respiratory problems), providing a framework for eco-epidemiological risk assessment. This approach enhances targeted intervention planning, resource allocation, and early warning systems, particularly in resource-limited settings like the Philippines. The study underscores the role of Maximum Entropy in addressing re-emerging diseases, contributing to sustainable public health preparedness and mitigation strategies in tropical regions given that there is currently no predictive model for pertussis cases in the Philippines.

Identification of Environmental Determinants Involved in the Distribution of Burkholderia pseudomallei in Southeast Asia using MaxEnt software

Burkholderia pseudomallei (Bp), causing melioidosis, is becoming a major global public health concern. It is highly endemic in Southeast Asia (SEA) and Northern Australia and is persisting beyond the established areas of endemicity. This study aimed to determine the environmental variables that would predict the most suitable ecological niche for this pathogenic bacterium in SEA by maximum entropy (MaxEnt) modeling. Systematic review and meta-analysis of data for melioidosis were obtained from public databases such as PubMed, Harmonized World Soil (HWSD) and WorldClim. The potential map showing the environmental layers was processed by ArcGIS, and the prediction for the probability of habitat suitability using MaxEnt software (version 3·4·4) and ENMeval R-based modeling tools was utilized to generate the distribution map with the best-fit model. Both bioclimatic and edaphic predictors were found to be the most important niche-determining environmental variables affecting the geographical distribution of Bp. The highest probability of suitability was predicted in areas with mean temperature of the wettest quarter at ≥26°C, annual precipitation of <2300 mm and Acrisol soil type. Combining those significantly influential variables, our predictive modeling generated a potential distribution map showing the concentration of areas and its location names with high suitability for Bp presence. The predicted distribution of Bp is extensive in the mainland part of SEA. This can be used to draw appropriate measures to safeguard public health and address the true disease burden of melioidosis in the region under the current climate scenario.

Peziza nivalis and relatives-spring fungi of wide distribution

Several members of the genus Peziza sensu stricto occur at the edge of melting snow. These nivicolous species have been widely reported in the Northern Hemisphere and are also known from Australia and New Zealand. We have used 16 specimens from North America and Australia to study morphology and to perform DNA sequencing. In sequence analyses, we have used ITS1 and ITS2 (internal transcribed spacers), 28S, RPB2 (RNA polymerase II gene), and two genes new to these studies, GAPDH (glyceraldehyde-3-phosphate dehydrogenase) and HSP90 (heat shock protein 90). Although not all regions are available for all samples, we have recognized the following species: Peziza heimii, P. nivalis, and P. nivis. Phylogenetic analyses were done using ITS alone; combined ITS1-5.8S-ITS2, 28S, and RPB2; ITS, and 28S, RPB2, GAPDH, and HSP90. Even with this augmented set of genes and despite their widespread occurrence in North America, Europe, Australia, and New Zealand, we have not definitively distinguished species within this group. To assess these results, pairwise homoplasy index (PHI) analysis was employed. This showed evidence of recombination among the samples of P. nivalis and further supports the view of P. nivalis as a monophyletic cosmopolitan species. As part of this study, we also examined the variation in ITS copies in P. echinospora, for which a genome is available.

MaxEnt modeling of the potential risk of schistosomiasis in the Philippines using bioclimatic factors

Schistosomiasis is a parasitic infection caused by Schistosoma japonicum. It remains a principal local health issue in the Philippines, demonstrating endemicity in 28 provinces and afflicting thousands of Filipino individuals annually. Despite this, no clear distribution maps for the disease have been comprehensively reported. Therefore, species distribution modeling (SDM) employing the MaxEnt algorithm and GIS application techniques was utilized to denote the potential risk of schistosomiasis in the country. With a high AUC score of 0.846, the SDM yielded a favorable and reliable correlative map illustrating a predicted schistosomal temporal distribution concentrated primarily on the country's eastern portion with a more pronounced wet than dry season. The precipitation of the driest quarter was determined to be the most significant contributing factor among the bioclimatic variables evaluated. This suggests a possible increase in adaptations concerning the rainfall and thermal tolerances of the parasites' vectors. Moreover, socioeconomic status between Philippine regions revealed an inverse proportion with the number of schistosomiasis cases. This study also discussed the potential role of climate change on the range shifts and the potential risk of parasite infection in the Philippines.

Predicting the potential nationwide distribution of the snail vector, Oncomelania hupensis quadrasi, in the Philippines using the MaxEnt algorithm

Schistosomiasis remains a major public health concern affecting approximately 12 million people in the Philippines due to inadequate information about the disease and limited prevention and control efforts. Schistosoma japonicum, one of the causative agents of the disease, requires an amphibious snail Oncomelania hupensis quadrasi (O. h. quadrasi) to complete its life cycle. Using the geographical information system (GIS) and maximum entropy (MaxEnt) algorithm, this study aims to predict the potential high-risk habitats of O. h. quadrasi driven by environmental factors in the Philippines. Based on the bioclimatic determinants, a very high-performance model was generated (AUC = 0.907), with the mean temperature of the driest quarter (25.3%) contributing significantly to the prevalence of O. h. quadrasi. Also, the snail vector has a high focal distribution, preferring areas with a pronounced wet season and high precipitation throughout the year. However, the findings provided evidence for snail adaptation to different environmental conditions. High suitability of snail habitats was found in Quezon, Camarines Norte, Camarines Sur, Albay, Sorsogon, Northern Samar, Eastern Samar, Leyte, Bohol, Surigao del Norte, Surigao del Sur, Agusan del Norte, Davao del Norte, North Cotabato, Lanao del Norte, Misamis Occidental, and Zamboanga del Sur. Furthermore, snail habitat establishment includes natural and man-made waterlogged areas, with the progression of global warming and climate change predicted to be drivers of increasing schistosomiasis transmission zones in the country.

High Environmentally Induced Plasticity in Spore Size and Numbers of Nuclei per Spore in Physarum albescens (Myxomycetes)

Spore size enables dispersal in plasmodial slime molds (Myxomycetes) and is an important taxonomic character. We recorded size and the number of nuclei per spore for 39 specimens (colonies of 50-1000 sporocarps) of the nivicolous myxomycete Physarum albescens, a morphologically defined taxon with several biological species. For each colony, three sporocarps were analyzed from the same spore mount under brightfield and DAPI-fluorescence, recording ca. 14,000 spores per item. Diagrams for spore size distribution showed narrow peaks of mostly uninucleate spores. Size was highly variable within morphospecies (10.6-13.5 µm, 11-13%), biospecies (3-13%), even within spatially separated colonies of one clone (ca. 8%); but fairly constant for a colony (mean variation 0.4 µm, ca. 1.5%). ANOVA explains most of this variation by the factor locality (within all colonies: 32.7%; within a region: 21.4%), less by biospecies (13.5%), whereas the contribution of intra-colony variation was negligible (<0.1%). Two rare aberrations occur: 1) multinucleate spores and 2) oversized spores with a double or triple volume of normal spores. Both are not related to each other or limited to certain biospecies. Spore size shows high phenotypic plasticity, but the low variation within a colony points to a strong genetic background.