Infection Levels Research Articles

Improving the Cost-efficiency of Preventive Chemotherapy: Impact of New Diagnostics on Stopping Decisions for Control of Schistosomiasis.

Control of schistosomiasis (SCH) relies on the regular distribution of preventive chemotherapy (PC) over many years. For the sake of sustainable SCH control, a decision must be made at some stage to scale down or stop PC. These "stopping decisions" are based on population surveys that assess whether infection levels are sufficiently low. However, the limited sensitivity of the currently used diagnostic (Kato-Katz [KK]) to detect low-intensity infections is a concern. Therefore, the use of new, more sensitive, molecular diagnostics has been proposed. Through statistical analysis of Schistosoma mansoni egg counts collected from Burundi and a simulation study using an established transmission model for schistosomiasis, we investigated the extent to which more sensitive diagnostics can improve decision making regarding stopping or continuing PC for the control of S. mansoni. We found that KK-based strategies perform reasonably well for determining when to stop PC at a local scale. Use of more sensitive diagnostics leads to a marginally improved health impact (person-years lived with heavy infection) and comes at a cost of continuing PC for longer (up to around 3 years), unless the decision threshold for stopping PC is adapted upward. However, if this threshold is set too high, PC may be stopped prematurely, resulting in a rebound of infection levels and disease burden (+45% person-years of heavy infection). We conclude that the potential value of more sensitive diagnostics lies more in the reduction of survey-related costs than in the direct health impact of improved parasite control.

SARS-CoV-2 tropism to intestinal but not gastric epithelial cells is defined by limited ACE2 expression

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection primarily affects the lung but can also cause gastrointestinal (GI) symptoms. Invitro experiments confirmed that SARS-CoV-2 robustly infects intestinal epithelium. However, data on infection of adult gastric epithelium are sparse and a side-by-side comparison of the infection in the major segments of the GI tract is lacking. We provide this direct comparison in organoid-derived monolayers and demonstrate that SARS-CoV-2 robustly infects intestinal epithelium, while gastric epithelium is resistant to infection. RNA sequencing and proteome analysis pointed to angiotensin-converting enzyme 2 (ACE2) as a critical factor, and, indeed, ectopic expression of ACE2 increased susceptibility of gastric organoid-derived monolayers to SARS-CoV-2. ACE2 expression pattern in GI biopsies of patients mirrors SARS-CoV-2 infection levels in monolayers. Thus, local ACE2 expression limits SARS-CoV-2 expression in the GI tract to the intestine, suggesting that the intestine, but not the stomach, is likely to be important in viral replication and possibly transmission.

How Does the Proportion of Never Treatment Influence the Success of Mass Drug Administration Programs for the Elimination of Lymphatic Filariasis?

Mass drug administration (MDA) is the cornerstone for the elimination of lymphatic filariasis (LF). The proportion of the population that is never treated (NT) is a crucial determinant of whether this goal is achieved within reasonable time frames. Using 2 individual-based stochastic LF transmission models, we assess the maximum permissible level of NT for which the 1% microfilaremia (mf) prevalence threshold can be achieved (with 90% probability) within 10 years under different scenarios of annual MDA coverage, drug combination and transmission setting. For Anopheles-transmission settings, we find that treating 80% of the eligible population annually with ivermectin + albendazole (IA) can achieve the 1% mf prevalence threshold within 10 years of annual treatment when baseline mf prevalence is 10%, as long as NT <10%. Higher proportions of NT are acceptable when more efficacious treatment regimens are used. For Culex-transmission settings with a low (5%) baseline mf prevalence and diethylcarbamazine + albendazole (DA) or ivermectin + diethylcarbamazine + albendazole (IDA) treatment, elimination can be reached if treatment coverage among eligibles is 80% or higher. For 10% baseline mf prevalence, the target can be achieved when the annual coverage is 80% and NT ≤15%. Higher infection prevalence or levels of NT would make achieving the target more difficult. The proportion of people never treated in MDA programmes for LF can strongly influence the achievement of elimination and the impact of NT is greater in high transmission areas. This study provides a starting point for further development of criteria for the evaluation of NT.

Analyzing the Capacity of the Healthcare System in Gaza to Address Gaza Residents Needs

The present humanitarian crisis in Gaza has resulted in the devastation of medical facilities and health infrastructure. As of January 2024, the World Health Organization reports that 78% of primary care clinics funded by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA, 2024) have ceased operations, and hospitals’ bed capacity throughout Gaza has decreased by more than 59% (World Health Organization, 2024). Direct military attacks on medical facilities as well as the blockade of medical supplies and humanitarian aid pose the largest obstacles to greater healthcare attainment in Gaza (IRC, 2024). Over the course of the conflict, there has been a surge in the number of people suffering from war injuries, which now totals 71,377 (Shurafa, 2024). The rise in the number of patients who require access to medical services in combination with the limited hospital functionality in the Gaza Strip is putting a massive strain on their already limited healthcare system; before the over 6 month long duration of direct military attacks by the Israeli Defence Forces (IDF) on hospitals in Gaza, data indicated a maximum ratio of 1.55 hospital beds per 1000 individuals across the entire region of the Gaza Strip, while the ratio in the US is around 2.35 hospital beds per 1000 individuals (Taylor, 2024). The already poor living conditions of the demographic–most of whom are housed in temporary structures in severe weather conditions with a lack of access to food and water for sustenance or hygiene–signify a need for a more robust healthcare system. However, triage conditions prioritize treatment of the most severe war injuries, which has forced hospitals to abandon previously established vaccination projects and disease surveillance programs, leaving the remaining population to suffer from preventable diseases such as chickenpox, upper respiratory infections, scabies, and Hepatitis A (Soni, 2024). Individuals who do receive medical care face higher levels of infection due to a lack of adequate sanitation, waste management measures, and basic hygiene supplies (The Economist, 2024).

Reducing the Antigen Prevalence Target Threshold for Stopping and Restarting Mass Drug Administration for Lymphatic Filariasis Elimination: A Model-Based Cost-effectiveness Simulation in Tanzania, India and Haiti.

The Global Programme to Eliminate Lymphatic Filariasis (GPELF) aims to reduce and maintain infection levels through mass drug administration (MDA), but there is evidence of ongoing transmission after MDA in areas where Culex mosquitoes are the main transmission vector, suggesting that a more stringent criterion is required for MDA decision making in these settings. We use a transmission model to investigate how a lower prevalence threshold (<1% antigenemia [Ag] prevalence compared with <2% Ag prevalence) for MDA decision making would affect the probability of local elimination, health outcomes, the number of MDA rounds, including restarts, and program costs associated with MDA and surveys across different scenarios. To determine the cost-effectiveness of switching to a lower threshold, we simulated 65% and 80% MDA coverage of the total population for different willingness to pay per disability-adjusted life-year averted for India ($446.07), Tanzania ($389.83), and Haiti ($219.84). Our results suggest that with a lower Ag threshold, there is a small proportion of simulations where extra rounds are required to reach the target, but this also reduces the need to restart MDA later in the program. For 80% coverage, the lower threshold is cost-effective across all baseline prevalences for India, Tanzania, and Haiti. For 65% MDA coverage, the lower threshold is not cost-effective due to additional MDA rounds, although it increases the probability of local elimination. Valuing the benefits of elimination to align with the GPELF goals, we find that a willingness to pay per capita government expenditure of approximately $1000-$4000 for 1% increase in the probability of local elimination would be required to make a lower threshold cost-effective. Lower Ag thresholds for stopping MDAs generally mean a higher probability of local elimination, reducing long-term costs and health impacts. However, they may also lead to an increased number of MDA rounds required to reach the lower threshold and, therefore, increased short-term costs. Collectively, our analyses highlight that lower target Ag thresholds have the potential to assist programs in achieving lymphatic filariasis goals.

Optimal species composition for stand establishment in root-rot infected forest areas

Heterobasidion root rot causes severe problems in the coniferous dominated forests of Northern hemisphere by decreasing timber value, reducing tree growth and making trees prone to other disturbance agents such as wind and bark beetles. According to current practices an infected stand is protected by treating fresh stumps at final cutting and generating the stand with tree species other than the host to reduce the current infection levels. However, prevailing guidelines do not provide instructions how to manage the neighbouring stands around the already infected stand. In contrast to earlier studies, we expand the analysis to an entity (a landscape) consisting of both infected and uninfected stands so that stand establishment of uninfected area is taken into account, too. The objective of the study is to optimize stand establishment of the uninfected area so that the revenue losses are simultaneously minimized when the average carbon storage is maximized within the whole landscape (infected + uninfected). Our results demonstrate the complexity of Heterobasidion root rot management: the optimum stand establishment strategy differs depending on the geographic location and interest rate (i.e., yield on capital). Further, the results implicate that for successful fight against Heterobasidion root rot the magnitude of infected area as well as the severity of the infection need to be taken into account.

SARS-CoV-2 Omicron BA.1 Variant Infection of Human Colon Epithelial Cells.

The Omicron variant of SARS-CoV-2, characterized by multiple subvariants including BA.1, XBB.1.5, EG.5, and JN.1, became the predominant strain in early 2022. Studies indicate that Omicron replicates less efficiently in lung tissue compared to the ancestral strain. However, the infectivity of Omicron in the gastrointestinal tract is not fully defined, despite the fact that 70% of COVID-19 patients experience digestive disease symptoms. Here, using primary human colonoids, we found that, regardless of individual variability, Omicron infects colon cells similarly or less effectively than the ancestral strain or the Delta variant. The variant induced limited type III interferon expression and showed no significant impact on epithelial integrity. Further experiments revealed inefficient cell-to-cell spread and spike protein cleavage in the Omicron spike protein, possibly contributing to its lower infectious particle levels. The findings highlight the variant-specific replication differences in human colonoids, providing insights into the enteric tropism of Omicron and its relevance to long COVID symptoms.

Stability and integrity of self-assembled bovine parvovirus virus‑like particles (BPV‑VLPs) of VP2 and combination of VP1VP2 assisted by baculovirus-insect cell expression: a potential logistical platform for vaccine deployment

BackgroundBovine parvovirus (BPV) is an autonomous DNA virus with a smaller molecular size and subtle differences in its structural proteins, unlike other animal parvoviruses. More importantly, this virus has the potential to produce visible to silent economic catastrophes in the livestock business, despite receiving very little attention. Parvoviral virus-like particles (VLPs) as vaccines and as logistical platforms for vaccine deployment are well studied. However, no single experimental report on the role of VP1 in the assembly and stability of BPV-VLPs is available. Furthermore, the self-assembly, integrity and stability of the VLPs of recombinant BPV VP2 in comparison to VP1 VP2 Cap proteins using any expression method has not been studied previously. In this study, we experimentally evaluated the self-assembling ability with which BPV virus-like particles (VLPs) could be synthesized from a single structural protein (VP2) and by integrating both VP2 and VP1 amino acid sequences.MethodsIn silico and experimental cloning methods were carried out. His-tagged and without-His-tag VP2 and V1VP2-encoding amino acid sequences were cloned and inserted into pFastbacdual, and insect cell-generated recombinant protein was evaluated by SDS‒PAGE and western blot. Period of infectivity and expression level were determined by IFA. The integrity and stability of the BPV VLPs were evaluated by transmission electron microscopy. The secondary structure of the BPV VLPs from both VP2 and V1VP2 was analyzed by circular dichroism.ResultsOur findings show that VP2 alone was equally expressed and purified into detectable proteins, and the stability at different temperatures and pH values was not appreciably different between the two kinds of VLPs. Furthermore, BPV-VP2 VLPs were praised for their greater purity and integrity than BPV-VP1VP2 VLPs, as indicated by SDS‒PAGE. Therefore, our research demonstrates that the function of VP1 has no bearing on the stability or integrity of BPV-VLPs.ConclusionsIn summary, incredible physiochemically stable BPV VP2-derived VLPs have been found to be promising candidates for the development of multivalent vaccines and immunodiagnostic kits against enteric viruses and to carry heterogeneous epitopes for various economically important livestock diseases.

Location and elimination of Anisakis simplex third stage larvae in Atlantic herring Clupea harengus L

We here describe the location of anisakid third stage larvae in Atlantic herring Clupea harengus L. caught in the North Sea in August 2023. We further demonstrate how industrial processing (mechanical gutting, removal of entrails, head, tail, hypaxial anterior musculature and vertebral column) reduces the overall infection and worm load in the musculature. The isolated anisakid larvae were identified as Anisakis simplex sensu stricto by a combination of morphometrics and molecular methods (PCR of rDNA and mtDNA, sequencing, BLAST analysis). As a baseline we examined a total of 75 specimens of freshly caught and ungutted herring and showed a positive correlation between host size (fish length and weight) and infection level. The overall prevalence of infection was 84 %, the mean intensity 11.3 (range 1–38 parasites per fish) and the abundance 9.52. The main part of the overall worm population was associated with stomach and pyloric caeca in the body cavity (77 %) and only 5 % was found in the musculature. Larvae occurred in the hypaxial part of the musculature (21), the epaxial part (7 worms) and the caudal part (5 worms). The prevalence of muscle infection was 28 % and the mean intensity 1.6 (range 1–5) parasites per fish and abundance 0.44 parasites per fish. In order to assess the effect of industrial processing on worm occurrence in the fish we examined a total of 67 specimens of herring, from exactly the same batch, but following processing. This included removal of organs in the body cavity, cutting the lower part of the hypaxial segment but leaving the right and left musculature connected by dorsal connective tissue. Five out of these fish carried one larva (prevalence 7.5%, mean intensity 1, abundance 0.07 larvae per fish), and these worms were located in the ventral part of the anterior musculature (2), in the central part of the anterior musculature (2) and one larva in the central part of the caudal musculature. The industrial processing reduced the overall occurrence (abundance) of worms in the fish from 9.52 to 0.07 (136 times reduction) and the occurrence in the musculature from 0.44 to 0.07 (6.28 times reduction). The overall prevalence was reduced from 84 % to 7.5 % (11.2 times reduction). Muscle infection prevalence fell from 28 % to 7.5 % (3.7 times reduction). We then followed another batch of herring following a marinating process (11% NaCl for 24 h and subsequent incubation in acetic acid and vinegar) by artificially digesting the flaps during week 1–8. Although a total of 31 larvae were recovered from 144 fish examined no live nematode larvae were isolated. The importance of fish handling, processing and marination for consumer safety is discussed.

Stability and purity of selected ryegrass Epichloë endophytes in New Zealand dairy pastures

AbstractBackgroundPerennial ryegrass (Lolium perenne) in New Zealand pastures is typically infected with the mutualist Epichloë fungal endophyte. This endophyte assists the plant in resisting biotic and abiotic stresses, but the standard strain of endophyte is toxic to livestock. Elite ryegrasses with selected endophytes have been developed to provide protective properties to the grass plant and lessen or eliminate the negative impacts on livestock.MethodsUsing immunology and molecular techniques, the presence of endophyte infection and endophyte strain in ryegrass tillers was determined for 24 dairy pastures sampled for up to 7 years in regions of the North and South Islands.ResultsIn general, infection levels were high and showed small increases over time. Some pastures failed to reach 70% infection. The sown, selected endophytes were the dominant endophyte strains present and these were stable over time. Standard endophyte was the primary nonsown endophyte, and while generally low and so of little importance, it increased over time and for some pastures, this would have been detrimental to livestock. Pasture establishment technique influenced the level of contamination.ConclusionsResults reinforce the importance of following best practice procedures in the seed industry and on‐farm. Researchers should monitor trials for contaminating nonsown standard endophyte.

Effects of the COVID-19 pandemic on short-term postoperative outcomes of emergency surgery for gastroduodenal perforation: A nationwide study in Japan based on the National Clinical Database.

To examine the potential negative effects of the COVID-19 pandemic on short-term postoperative outcomes of emergency surgery for gastroduodenal perforation in Japan. A total of 7973 cases of gastroduodenal perforation from 2019 to 2021 were retrieved from the National Clinical Database (NCD), which includes >95% of surgical cases in Japan. Data were analyzed nationally and in subgroups for subjects in areas with high infection levels (HILs). Postoperative 30-d mortality, surgical mortality, and complications (Clavien-Dindo (CD) grade ≥3) were examined. Months were considered to have significantly high or low mortality or complication rates, if the 95% confidence interval (CI) of the standardized mortality (morbidity) ratio (SMR) does not contain 1. Nationally, data from 2019 vs 2020 and 2021 showed 30-d mortality of 175 (6.7%) vs 398 (7.4%), surgical mortality of 250 (9.5%) vs 537 (10.1%), and complications (CD ≥3) of 558 (21.2%) vs 1163 (21.8%). Among these data, the only significantly high SMR was found for complications in July 2020 (1.36 [95% CI: 1.001-1.80]). In areas with HILs, data from 2019 vs 2020 and 2021 indicated 30-d mortality of 91 (6.3%) vs 215 (7.3%), surgical mortality of 135 (9.4%) vs 294 (10.0%), and complications (CD ≥3) of 304 (21.1%) vs (23.1%). In these data, no month had a significantly high SMR. The COVID-19 pandemic had few negative effects on outcomes after surgery for gastroduodenal perforation. These findings suggest that the emergency system for gastroduodenal perforation in Japan was generally maintained during the pandemic.

Characterization of volatile compounds from healthy and citrus black spot-infected Valencia orange juice and essential oil by using gas chromatography–mass spectrometry

Citrus black spot (Phyllosticta citricarpa, CBS) is an important fungal disease that causes rind blemishes and affects quality of citrus fruits. The response of citrus to CBS in terms of volatiles was evaluated using molecular sensory science approaches. Fifty and twenty-one volatiles were identified in the orange juice and essential oil samples, respectively, via gas chromatography–mass spectrometry (GC–MS). The total volatile content in the samples increased after CBS infection, especially in the severe-infection group (SEG) juice and moderate-infection group (MOG) essential oil, which reached the highest levels. CBS enhanced floral, fruity, and off-flavor aromas and decreased the green aroma in citrus juice. Citrusy, floral, and green aromas increased in the CBS-infected essential oil. Six/five potential markers were screened in citrus juice/essential oil, respectively using the orthogonal partial least-square discriminant analysis (OPLS-DA) model. The changes in aroma profile and the difference in infection levels in citrus were attributed to these odorants.

Prevalence, genetic diversity and eco-epidemiology of pathogenic Leptospira species in small mammal communities in urban parks Lyon city, France.

Rodents are recognized as the main reservoirs of Leptospira spp. Rats, in particular, serve as hosts for the widely predominant Leptospira interrogans serovar Icterohaemorrhagiae, found worldwide. Several studies have shown the importance of other reservoirs, such as mice or hedgehogs, which harbor other leptospires' serovars. Nevertheless, our knowledge of circulating Leptospira spp. in reservoirs other than rats remains limited. In this context, we proposed an eco-health approach to assess the health hazard associated with leptospires in urban green spaces, where contacts between human/small mammals and domestic animals are likely. We studied the prevalence, the diversity of circulating strains, and epidemiology of pathogenic Leptospira species in small terrestrial mammal communities (rodents and shrews), between 2020-2022, in two parks in Lyon metropolis, France. Our study showed a significant carriage of Leptospira spp. in small terrestrial mammals in these parks and unveiled a global prevalence rate of 11.4%. Significant variations of prevalence were observed among the small mammal species (from 0 to 26.1%), with Rattus norvegicus exhibiting the highest infection levels (26.1%). We also observed strong spatio-temporal variations in Leptospira spp. circulation in its reservoirs. Prevalence seems to be higher in the peri-urban park and in autumn in 2021 and 2022. This is potentially due to differences in landscape, abiotic conditions and small mammal communities' composition. Our study suggests an important public health relevance of rats and in a lesser extent of other rodents (Apodemus spp., Clethrionomys glareolus and Mus musculus) as reservoirs of L. interrogans, with rodent species carrying specific serogroups/serovars. We also emphasize the potential hazard associated between the shrew Crocidura russula and L. kirschneri. Altogether, these results improve our knowledge about the prevalence of leptospirosis in an urban environment, which is an essential prerequisite for the implementation of prevention of associated risks.

A 2D-proteomic analysis identifies proteins differentially regulated by two different dengue virus serotypes

The mosquito transmitted dengue virus (DENV) is a major public health problem in many tropical and sub-tropical countries around the world. Both vaccine development and drug development are complex as the species Dengue virus consist of four distinct viruses (DENV 1 to DENV 4) each of which is composed of multiple lineages and strains. To understand the interaction of DENV with the host cell machinery, several studies have undertaken in vitro proteomic analysis of different cell lines infected with DENV. Invariably, these studies have utilized DENV 2. In this study we sought to define proteins that are differentially regulated by two different DENVs, DENV 2 and DENV 4. A 2-dimensional proteomic analysis identified some 300 protein spots, of which only 11 showed differential expression by both DENVs. Of these, only six were coordinately regulated. One protein, prohibitin 1 (PHB1) was downregulated by infection with both DENVs. Overexpression of PHB1 increased DENV protein expression, level of infection and genome copy number. DENV E protein colocalized with PHB, and there was a direct interaction between DENV 2 E protein and PHB1, but not between DENV 4 E protein and PHB1. The low number of proteins showing coordinate regulation after infection by different DENVs is a cause for concern, particularly in determining new druggable targets, and suggests that studies should routinely investigate multiple DENVs.

A porcine kidney-derived clonal cell line with clear genetic annotation is highly susceptible to African swine fever virus

African Swine Fever virus (ASFV), the causative agent of African swine fever, is a highly lethal hemorrhagic virus affecting domestic pigs and wild boars. The primary target cells for ASFV infection are porcine alveolar macrophages (PAMs), which are difficult to obtain and maintain in vitro, and less subjective to genetic editing. To overcome these issues and facilitate ASFV research, we obtained a subclonal cell line PK1-C5 by subcloning LLC-PK1 cells that support stable ASFV proliferation. This consequential cell line exhibited high ASFV infection levels and similar viral growth characteristics to PAMs, while also allowing high-efficiency genomic editing through transfection or lentivirus transduction of Cas9. Taken together, our study provided a valuable tool for research aspects including ASFV-host interactions, pathogenicity, and vaccine development.

Clinical significance of elevated D-dimer in emergency department patients: a retrospective single-center analysis

IntroductionD-dimer is a marker of coagulation and fibrinolysis widely used in clinical practice for assessing thrombotic activity. While it is commonly ordered in the Emergency Department (ED) for suspected venous thromboembolism (VTE), elevated D-dimer levels can occur due to various other disorders. The aim of this study was to find out the causes of elevated D-dimer in patients presenting to a large ED in Saudi Arabia and evaluate the accuracy of D-dimer in diagnosing these conditions.MethodsData was collected from an electronic hospital information system of patients who visited the ED from January 2016 to December 2022. Demographic information, comorbidities, D-dimer levels, and diagnoses were analyzed. Statistical analysis was performed using the SPSS software. The different diagnoses associated with D-dimer levels were analyzed by plotting the median D-dimer levels for each diagnosis category and their interquartile ranges (IQR). The receiver operating characteristic (ROC) curves were calculated and their area under the curve (AUC) values were demonstrated. The optimal cut-off points for specific diseases were determined based on the ROC analysis, along with their corresponding sensitivities and specificities.ResultsA total of 19,258 patients with D-dimer results were included in the study. The mean age of the participants was 50 years with a standard deviation of ± 18. Of the patients, 66% were female and 21.2% were aged 65 or above. Additionally, 21% had diabetes mellitus, 20.4% were hypertensive, and 15.1% had been diagnosed with dyslipidemia. The median D-dimer levels varied across different diagnoses, with the highest level observed in aortic aneurysm 5.46 g/L. Pulmonary embolism (PE) and deep vein thrombosis (DVT) were found in 729 patients (3.8%) of our study population and their median D-dimer levels 3.07 g/L (IQR: 1.35–7.05 g/L) and 3.36 g/L (IQR: 1.06–8.38 g/L) respectively. On the other hand, 1767 patients (9.2%) were diagnosed with respiratory infections and 936 patients (4.9%) were diagnosed with shortness of breath (not specified) with median D-dimer levels of 0.76 g/L (IQR: 0.40–1.47 g/L) and 0.51 g/L (IQR: 0.29–1.06 g/L), respectively. D-dimer levels showed superior or excellent discrimination for PE (AUC = 0.844), leukemia (AUC = 0.848), and aortic aneurysm (AUC = 0.963). DVT and aortic dissection demonstrated acceptable discrimination, with AUC values of 0.795 and 0.737, respectively. D-dimer levels in respiratory infections and shortness of breath (not specified) exhibited poor to discriminatory performance.ConclusionThis is the first paper to identify multiple causes of elevated D-dimer levels in Saudi Arabia population within the ED and it clearly highlights their accurate and diagnostic values. These findings draw attention to the importance of considering the specific clinical context and utilizing additional diagnostic tools when evaluating patients with elevated D-dimer levels.

The private management of plant disease epidemics: infection levels and social inefficiencies

The private management of plant disease epidemics: infection levels and social inefficiencies

A Tomato-Free Period Delays and Reduces Begomovirus Disease in Processing Tomato Fields in a Complex Agroecosystem in Central Brazil.

A mandatory tomato-free period (TFP) was implemented in the state of Goiás, Brazil, in 2007 to help manage diseases caused by whitefly-transmitted begomoviruses. The impact of the TFP was examined in five locations across three states in Central Brazil from 2013 to 2016. Surveys revealed significant differences in begomovirus disease incidence among locations, i.e., low in Guaíra-TFP and Patos de Minas-TFP; moderate-high in Itaberaí-TFP and Morrinhos-TFP; and high in the non-TFP (NTFP) control, Cristalina-NTFP. PCR tests and DNA sequencing were used to validate the symptoms and showed that all collected symptomatic plant samples were infected with tomato severe rugose virus (ToSRV), a common indigenous bipartite begomovirus. Early season surveys (20 to 40 days after transplants [DAT]) in Itaberaí-TFP and Morrinhos-TFP revealed significantly less begomovirus disease in fields established sooner after the TFP (0 to 2 months) compared with incidences in (i) equivalent early planted fields in the Cristalina-NTFP control and (ii) fields established longer after the end of the TFP (>2 to 5 months). Whitefly infestation of crops was detected year-round in all locations and years, and all tested adults were classified in the Bemisia tabaci MEAM1 cryptic species. Infestation levels were significantly higher during the summer but did not vary significantly among locations. Results of monthly monitoring of adult whiteflies for general begomovirus and ToSRV were positively correlated and were indicators of disease incidence in the field. Notably, ToSRV was not detected in whiteflies collected from nontomato plants during the TFP, and there was a longer lag period before detection in whiteflies collected from processing tomatoes for Itaberaí-TFP and Morrinhos-TFP compared with Cristalina-NTFP. Taken together with the low levels of ToSRV infection detected in potential nontomato reservoir hosts at all locations, our results revealed low levels of primary inoculum during the TFP. Thus, even in a complex agroecosystem with year-round whitefly infestation of crops, the TFP was beneficial due to delayed and reduced begomovirus disease pressure during a critical stage of plant development (first month) and for favoring low levels of primary inoculum. Thus, we concluded that the TFP should be part of a regional integrated pest management (IPM) program targeting ToSRV in Brazil.

Estimating the Effects of Regulating In-Person University Lectures on the Spread of COVID-19: Evidence from Japan

Universities were the only educational institutions that restricted in-person lectures during the prolonged coronavirus disease 2019 (COVID-19) pandemic. This study is the first attempt to estimate the effects of restricting in-person lectures on containing the spread of COVID-19. Our investigation was conducted on Japanese universities since their various lecture styles are suitable for our analysis. A multiple-event study negative binomial regression model was employed, and the results showed that restricting the ratio of in-person lectures had limited effects on decreasing COVID-19 infections among university students. For example, if universities restrict almost all in-person lecture from a rate of over half of in-person lectures, the number of student infections would decline by 5.5 per 10,000 students between seven weeks before and after the change. Other lecture style changes had even smaller differences. In addition, we estimated the effect of the start of long breaks on the number of infections and found that they lead to a relatively higher level of infections regardless of lecture styles at the end of semesters. This implies that students are more likely to be infected outside than in class.

Inhibition of gut digestive proteases by cyanobacterial diets decreases infection in a Daphnia host-parasite system.

Secondary metabolites produced by primary producers have a wide range of functions as well as indirect effects outside the scope of their direct target. Research suggests that protease inhibitors produced by cyanobacteria influence grazing by herbivores and may also protect against parasites of cyanobacteria. In this study, we asked whether those same protease inhibitors produced by cyanobacteria could also influence the interactions of herbivores with their parasites. We used the Daphnia-Metschnikowia zooplankton host-fungal parasite system to address this question because it is well documented that cyanobacteria protease inhibitors suppress trypsin and chymotrypsin in the gut of Daphnia, and because it is known that Metschnikowia infects via the gut. We tested the hypothesis that Daphnia gut proteases are necessary for Metschnikowia spores to be released from their asci. We then also tested whether diets that decrease trypsin and chymotrypsin activity in the guts of Daphnia lead to lower levels of infection. Our results show that chymotrypsin promotes the release of the fungal spores from their asci. Moreover, a diet that strongly inhibited chymotrypsin activity in Daphnia decreased infection levels, particularly in the most susceptible Daphnia clones. Our results support the growing literature that cyanobacterial diets can be beneficial to zooplankton hosts when challenged by parasites and uncover a mechanism that contributes to the protective effect of cyanobacterial diets. Specifically, we demonstrate that host chymotrypsin enzymes promote the dehiscence of Metschnikowia spores; when cyanobacteria inhibit the activity of chymotrypsin in hosts, this most likely traps the spore inside the ascus, preventing the parasite from puncturing the gut and beginning the infection process. This study illustrates how secondary metabolites of phytoplankton can protect herbivores against their own enemies.