The latest medical research on Tropical Medicine

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about tropical medicine gathered by our medical AI research bot.

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Trend analysis of malaria surveillance data in West Wallaga, West Oromia, Ethiopia: a framework for planning and elimination.

Malaria Journal

Although Ethiopia has made a remarkable progress towards malaria prevention and control, malaria remains one of the most devastating parasitic diseases affecting humans. However, the distribution and transmission of malaria varies across the country. The study aimed to describe 5 years of malaria distribution and magnitude within the West Wallaga Zone and its respective woredas.

A retrospective cross-sectional study design was conducted from April 10, 2019 to May 2019. Surveillance data collected weekly for a 5-year (2014-2018) from health facilities and private clinics that were archived in zonal PHEM database were reviewed. The checklist contained variety of variables was developed to collect data. Descriptive analysis was conducted to determine the proportion of Plasmodium species, positivity rate, mortality and fatality rate, time trend, and admission status; and presented by text, tables and figures.

Of the total of 588,119 suspected malaria cases, 78,658 (43/1000 populations) were positive with average positivity rate of 13.4%. Among confirmed cases, 59,794 (75%) of cases were attributed to Plasmodium falciparum, 16,518 (20%) were Plasmodium vivax, and 2,360 (5%) were mixed infections. The maximum (145,091) and minimum (74,420) transmissions were reported in 2014 and 2018, respectively. There was seasonal variation in transmission; spring (from May to July) and also autumn seasons (from October to November) were found as malaria transmission peaks. Although incidence rate declined throughout the study period, the average annual incidence rate was 14.38 per 1000 populations. The average case fatality rate of 5 consecutive years was 12/78,658 (15/100,000) population.

Although the malaria prevalence was decreased, the mortality due to malaria was increased in the 5-year study period, and malaria is still among the major public health problems. The dominant species of malaria parasites were P. falciparum and P. vivax. Attention is needed in scaling-up vector control tools in high malaria transmission periods.

Risk factors for non-participation in ivermectin and dihydroartemisinin-piperaquine mass drug administration for malaria control in the MASSIV trial.

Malaria Journal

The MASSIV trial is registered under NCT03576313.

Coverage data was extracted from the MASSIV trial study database, with every datapoint being a directly observed therapy (DOT). A complete month of MDA was classified as receiving all three daily doses of treatment. For both ivermectin and DHP, ordinal logistic regression was used to identify individual and household level variables associated with non-participation.

For ivermectin, 51.5% of eligible participants received all 3 months of treatment while 30.7% received either one or two complete months. For DHP, 56.7% of eligible participants received all 3 months of treatment and 30.5% received either one or two complete months. Children aged 5-15 years and adults aged more than 50 years were more likely to receive at least one complete month of MDA than working age adults, both for ivermectin (aOR 4.3, 95% CI 3.51-5.28 and aOR of 2.26, 95% CI 1.75-2.95) and DHP (aOR 2.47, 95%CI 2.02-3.02 and aOR 1.33, 95%CI 1.01-1.35), respectively. Members of households where the head received a complete month of MDA were more likely to themselves have received a complete month of MDA, both for ivermectin (aOR 1.71, 95%CI 1.35-2.14) and for DHP (aOR 1.64, 95%CI 1.33-2.04).

Personal and household-level variables were associated with participation in the MDA programme for malaria control. Specific strategies to (increase participation amongst some groups may be important to ensure maximum impact of MDA strategies in achieving malaria elimination.

Correlative light-electron microscopy methods to characterize the ultrastructural features of the replicative and dormant liver stages of Plasmodium parasites.

Malaria Journal

The infection of the liver by Plasmodium parasites is an obligatory step leading to malaria disease. Following hepatocyte invasion, parasites differentiate into replicative liver stage schizonts and, in the case of Plasmodium species causing relapsing malaria, into hypnozoites that can lie dormant for extended periods of time before activating. The liver stages of Plasmodium remain elusive because of technical challenges, including low infection rate. This has been hindering experimentations with well-established technologies, such as electron microscopy. A deeper understanding of hypnozoite biology could prove essential in the development of radical cure therapeutics against malaria.

The liver stages of the rodent parasite Plasmodium berghei, causing non-relapsing malaria, and the simian parasite Plasmodium cynomolgi, causing relapsing malaria, were characterized in human Huh7 cells or primary non-human primate hepatocytes using Correlative Light-Electron Microscopy (CLEM). Specifically, CLEM approaches that rely on GFP-expressing parasites (GFP-CLEM) or on an immunofluorescence assay (IFA-CLEM) were used for imaging liver stages. The results from P. berghei showed that host and parasite organelles can be identified and imaged at high resolution using both CLEM approaches. While IFA-CLEM was associated with more pronounced extraction of cellular content, samples' features were generally well preserved. Using IFA-CLEM, a collection of micrographs was acquired for P. cynomolgi liver stage schizonts and hypnozoites, demonstrating the potential of this approach for characterizing the liver stages of Plasmodium species causing relapsing malaria.

A CLEM approach that does not rely on parasites expressing genetically encoded tags was developed, therefore suitable for imaging the liver stages of Plasmodium species that lack established protocols to perform genetic engineering. This study also provides a dataset that characterizes the ultrastructural features of liver stage schizonts and hypnozoites from the simian parasite species P. cynomolgi.

The HIV epidemic in Haiti: is disability a factor?


People with disabilities (PWD) are thought to be low risk for HIV because of social norms regarding disability and sex. However, qualitative studie...

Identification of trans-genus biomarkers for early diagnosis of intestinal schistosomiasis and progression of gut pathology in a mouse model using metabolomics.

PLoS Neglected Tropical Diseases

Schistosomiasis is one of the most devastating human diseases worldwide. The disease is caused by six species of Schistosoma blood fluke; five of w...

Clonorchis sinensis on the prognosis of patients with spontaneous rupture of Hepatocellular Carcinoma: An inverse probability of treatment weighting analysis.

PLoS Neglected Tropical Diseases

We examined the impact of the Clonorchis sinensis (C. sinensis) infection on the survival outcomes of spontaneous rupture Hepatocellular Carcinoma (srHCC) patients undergoing hepatectomy.

Between May 2013 and December 2021, 157 consecutive srHCC patients who underwent hepatectomy were divided into an no C. sinensis group (n = 126) and C. sinensis group (n = 31). To adjust for differences in preoperative characteristics an inverse probability of treatment weighting (IPTW) analysis was done, using propensity scores. Overall survival (OS) and recurrence-free survival (RFS) were compared before and after IPTW. Multivariate Cox regression analysis was performed to determine whether the C. sinensis infection was an independent prognostic factor after IPTW.

In original cohort, the no C. sinensis group did not show a survival advantage over the C. sinensis group. After IPTW adjustment, the median OS for the C. sinensis group was 9 months, compared to 29 months for the no C. sinensis group. C. sinensis group have worse OS than no C. sinensis group (p = 0.024), while it did not differ in RFS(p = 0.065). The multivariate Cox regression analysis showed that C. sinensis infection and lower age were associated with worse OS.

The C. sinensis infection has an adverse impact on os in srHCC patients who underwent hepatectomy.

Parasites and microorganisms associated with the snakes collected for the "festa Dei serpari" in Cocullo, Italy.

PLoS Neglected Tropical Diseases

While in much of the Western world snakes are feared, in the small, rural, mountainous town of Cocullo, in the middle of central Italy, snakes are ...

Involving patients in drug development for Neglected Tropical Diseases (NTDs): A qualitative study exploring and incorporating preferences of patients with cutaneous leishmaniasis into Target Product Profile development.

PLoS Neglected Tropical Diseases

Target Product Profiles (TPPs) are instrumental to help optimise the design and development of therapeutics, vaccines, and diagnostics-these products, in order to achieve the intended impact, should be aligned with users' preferences and needs. However, patients are rarely involved as key stakeholders in building a TPP.

Thirty-three cutaneous leishmaniasis (CL) patients from Brazil, Colombia, and Austria, infected with New-World Leishmania species, were recruited using a maximum variation approach along geographic, sociodemographic and clinical criteria. Semi-structured interviews were conducted in the respective patient's mother tongue. Transcripts, translated into English, were analysed using a framework approach. We matched disease experiences, preferences, and expectations of CL patients to a TPP developed by DNDi (Drug for Neglected Diseases initiative) for CL treatment.

Patients' preferences regarding treatments ranged from specific efficacy and safety endpoints to direct and significant indirect costs. Respondents expressed views about trade-offs between efficacy and experienced discomfort/adverse events caused by treatment. Reasons for non-compliance, such as adverse events or geographical and availability barriers, were discussed. Considerations related to accessibility and affordability were relevant from the patients' perspective.

NTDs affect disadvantaged populations, often with little access to health systems. Engaging patients in designing adapted therapies could significantly contribute to the suitability of an intervention to a specific context and to compliance, by tailoring the product to the end-users' needs. This exploratory study identified preferences in a broad international patient spectrum. It provides methodological guidance on how patients can be meaningfully involved as stakeholders in the construction of a TPP of therapeutics for NTDs. CL is used as an exemplar, but the approach can be adapted for other NTDs.

Identification of tungiasis infection hotspots with a low-cost, high-throughput method for extracting Tunga penetrans (Siphonaptera) off-host stages from soil samples-An observational study.

PLoS Neglected Tropical Diseases

The sand flea, Tunga penetrans, is the cause of a severely neglected parasitic skin disease (tungiasis) in the tropics and has received little attention from entomologists to understand its transmission ecology. Like all fleas, T. penetrans has environmental off-host stages presenting a constant source of reinfection. We adapted the Berlese-Tullgren funnel method using heat from light bulbs to extract off-host stages from soil samples to identify the major development sites within rural households in Kenya and Uganda.

Simple, low-cost units of multiple funnels were designed to allow the extraction of >60 soil samples in parallel. We calibrated the method by investigating the impact of different bulb wattage and extraction time on resulting abundance and quality of off-host stages. A cross-sectional field survey was conducted in 49 tungiasis affected households. A total of 238 soil samples from indoor and outdoor living spaces were collected and extracted. Associations between environmental factors, household member infection status and the presence and abundance of off-host stages in the soil samples were explored using generalized models. The impact of heat (bulb wattage) and time (hours) on the efficiency of extraction was demonstrated and, through a stepwise approach, standard operating conditions defined that consistently resulted in the recovery of 75% (95% CI 63-85%) of all present off-host stages from any given soil sample. To extract off-host stages alive, potentially for consecutive laboratory bioassays, a low wattage (15-25 W) and short extraction time (4 h) will be required. The odds of finding off-host stages in indoor samples were 3.7-fold higher than in outdoor samples (95% CI 1.8-7.7). For every one larva outdoors, four (95% CI 1.3-12.7) larvae were found indoors. We collected 67% of all off-host specimen from indoor sleeping locations and the presence of off-host stages in these locations was strongly associated with an infected person sleeping in the room (OR 10.5 95% CI 3.6-28.4).

The indoor sleeping areas are the transmission hotspots for tungiasis in rural homes in Kenya and Uganda and can be targeted for disease control and prevention measures. The soil extraction methods can be used as a simple tool for monitoring direct impact of such interventions.

Conducting active screening for human African trypanosomiasis with rapid diagnostic tests: The Guinean experience (2016-2021).

PLoS Neglected Tropical Diseases

Strategies to detect Human African Trypanosomiasis (HAT) cases rely on serological screening of populations exposed to trypanosomes. In Guinea, mas...

Aedes aegypti CCEae3A carboxylase expression confers carbamate, organophosphate and limited pyrethroid resistance in a model transgenic mosquito.

PLoS Neglected Tropical Diseases

Insecticide resistance is a serious threat to our ability to control mosquito vectors which transmit pathogens including malaria parasites and arbo...

Transmission ecology of Trypanosoma cruzi by Rhodnius prolixus (Reduviidae: Triatominae) infesting palm-tree species in the Colombian Orinoco, indicates risks to human populations.

PLoS Neglected Tropical Diseases

Chagas disease, affecting approximately eight million individuals in tropical regions, is primarily transmitted by vectors. Rhodnius prolixus, a triatomine vector, commonly inhabits in ecotopes with diverse palm tree species, creating optimal conditions for vector proliferation. This study aims to explore the transmission ecology of Trypanosoma cruzi, the causative parasite of Chagas disease, by investigating the feeding patterns and natural infection rates of R. prolixus specimens collected from various wild palm species in the Colombian Orinoco region.

To achieve this objective, we sampled 35 individuals from three palm species (Attalea butyracea, Acrocomia aculeata, and Mauritia flexuosa) in a riparian forest in the Casanare department of eastern Colombia, totaling 105 sampled palm trees. DNA was extracted and analyzed from 115 R. prolixus specimens at different developmental stages using quantitative PCR (qPCR) for T. cruzi detection and identification of discrete typing units. Feeding preferences were determined by sequencing the 12S rRNA gene amplicon through next-generation sequencing.

A total of 676 R. prolixus specimens were collected from the sampled palms. The study revealed variation in population densities and developmental stages of R. prolixus among palm tree species, with higher densities observed in A. butyracea and lower densities in M. flexuosa. TcI was the exclusive T. cruzi discrete typing unit (DTU) found, with infection frequency positively correlated with R. prolixus abundance. Insects captured in A. butyracea exhibited higher abundance and infection rates than those from other palm species. The feeding sources comprised 13 mammal species, showing no significant differences between palm species in terms of blood sources. However, Didelphis marsupialis and Homo sapiens were present in all examined R. prolixus, and Dasypus novemcinctus was found in 89.47% of the insects.

This study highlights the significance of wild palms, particularly A. butyracea, as a substantial risk factor for T. cruzi transmission to humans in these environments. High population densities and infection rates of R. prolixus were observed in each examined palm tree species.