Association of Common Zoonotic Pathogens With Concentrated Animal Feeding Operations

Characterization of NFDQ1 in Cryptosporidium parvum

BACKGROUND

Cryptosporidium spp. are important zoonotic parasites that can cause moderate to severe diarrhea in humans and animals. Among the three Cryptosporidium species infecting the intestines of calves, Cryptosporidium parvum has a broad host range and causes severe diarrhea in calves, while Cryptosporidium bovis and Cryptosporidium ryanae mainly infect calves without obvious clinical symptoms. Comparative genomic analysis revealed differences in the copy number of genes encoding the nonfinancial disclosure quality (NFDQ) secretory protein family among the three species, suggesting that this protein family may be associated with the host range or pathogenicity of Cryptosporidium spp. To understand the function of cgd8_10 encoded NFDQ1, tagged and knockout strains were constructed and characterized in this study.

METHODS

To determine the localization of NFDQ1, we used clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) technology to tag the C-terminus of NFDQ1 with three hemagglutinin epitopes (3 × HA). The tagged strain was constructed, and the genomic insertion was confirmed by polymerase chain reaction (PCR). Immunofluorescence assays were performed to observe the localization of NFDQ1 both in extracellular sporozoites and at various intracellular developmental stages. Immunoelectron microscopy was used to study the ultrastructural localization of NFDQ1. Then, the ΔNFDQ1 strain was generated by CRISPR/Cas9 and the in vitro growth assay on HCT-8 cells was used to analyze of phenotypic changes after knockout NFDQ1 in parasites.

RESULTS

The NFDQ1 tagging and knockout stains were successfully constructed by CRISPR/Cas9 technology and the insertions of transgenic strains were validated by PCR. The expression of NFDQ1 was validated in parasite by western blot. Immunofluorescence and immune-electron microscopy assay showed that NFDQ1 expressed in both asexual and sexual stages of C. parvum, where it was localized to the cytoplasm of the parasite. Upon ablation of NFDQ1, the ΔNFDQ1 strain showed an apparent growth retardation during sexual replication in vitro.

CONCLUSIONS

NFDQ1 is a cytoplasmic protein without specific localization to secretory organelles, and it may participate in C. parvum growth during sexual reproduction. Future study should determine the role of NFDQ1 following C. parvum infection in vivo.

Sex-Specific Perching: Monitoring of Artificial Plants Reveals Dynamic Female-Biased Perching Behavior in the Black Soldier Fly, Hermetia illucens (Diptera: Stratiomyidae)

Artificial perches are implemented by many companies that mass-rear the black soldier fly (BSF), to emulate a natural breeding environment or provide additional surface area for flies to rest; however, basic information about perching behavior is lacking. This experiment tested the effect of adding 0.00, 0.04, 0.26, or 0.34 m2 of surface area to 0.93 m3 cages, each supplied with 90 male and 90 female adults. Female thoraxes marked with acrylic paint, and the number of perching flies of each sex were recorded over 6 d. A time-series analysis revealed the following: (a) females utilized perches 1.42 times more often than males across two trials; (b) especially in the morning where the difference could be as high as 2.56 times as great; (c) this decreased to 0.20-1.57 times more females than males by 1600 h; and (d) this cyclical pattern repeated each day throughout the week with a decreasing female-bias, starting from 2.41-times more females on day 1, which fell to 0.88-1.98-times more females than males on day 6. These dynamics are likely due to the presence of male flies engaging in aerial contests near ultraviolet lamps required for mating, especially during the early hours and early adulthood, aligning with and expanding prior knowledge of black soldier fly mating behavior.

Cellulose as a sustainable scaffold material in cultivated meat production

The rapid progress in cultivated meat research has engendered considerable attention towards the edible scaffolding biomaterials employed in the production. Cellulose has the advantages in availability, edibility, animal-free origin, etc., which show its potential in wide fields. This review begins by presenting the fundamental physical and chemical properties of cellulose from different sources, including plant and bacterial cellulose. Subsequently, we summarize the application of cellulose especially in cultivated meat and tissue engineering. Furthermore, we explore various methods for preparing cellulose-based scaffolds for cultivated meat, encompassing five specific structural variations. In the end, associated with utilizing cellulose in cultivated meat production, we address several primary challenges surrounding to cell adhesion, scaling up, processibility and mechanical properties, and provide potential innovations. This review underscores the potential of cellulose as a versatile biomaterial in the cultivated meat industry and provides insight into addressing critical challenges for its integration.

One Health Ethics and the Ethics of Zoonoses: A Silent Call for Global Action

This paper presents a critical review of key issues related to the emergence of new networks for the spread of zoonotic diseases amid the mass extinction of species. Zoonotic and infectious diseases account for approximately 70% of new and existing diseases affecting humans and animals. The initial section argues that the term "zoonoses" should not be confined to single-cause events within veterinary medicine. Instead, zoonoses should be viewed as complex, systemic phenomena shaped by interrelated factors, including environmental, sociocultural, and economic elements, influenced by anthropogenic climate change. The second section presents bioethical principles and potential strategies for those engaged in zoonotic disease prevention. The third section uses the slaughter of animals in disaster settings as a case study to illustrate the need for further clarification of normative and interspecies justice conflicts in One Health ethics. This section concludes with an outlook on "zoonoethics". Section four develops the analysis of the interlinked elements that trigger zoonoses and examines antimicrobial resistance (AMR) from an ethical and political standpoint, concluding with policy recommendations for addressing AMR. Section five offers a critical reflection, integrating contributions from zoonoethics, human ecology, and the ecotheological turn. Finally, section six concludes with a call to action and policy recommendations for an inclusive, intercultural, and gender-sensitive One Health approach.

Comparative genomics of Cryptosporidium parvum reveals the emergence of an outbreak-associated population in Europe and its spread to the United States

The zoonotic parasite Cryptosporidium parvum is a global cause of gastrointestinal disease in humans and ruminants. Sequence analysis of the highly polymorphic gp60 gene enabled the classification of C. parvum isolates into multiple groups (e.g., IIa, IIc, Id) and a large number of subtypes. In Europe, subtype IIaA15G2R1 is largely predominant and has been associated with many water- and food-borne outbreaks. In this study, we generated new whole-genome sequence (WGS) data from 123 human- and ruminant-derived isolates collected in 13 European countries and included other available WGS data from Europe, Egypt, China, and the United States (n = 72) in the largest comparative genomics study to date. We applied rigorous filters to exclude mixed infections and analyzed a data set from 141 isolates from the zoonotic groups IIa (n = 119) and IId (n = 22). Based on 28,047 high-quality, biallelic genomic SNPs, we identified three distinct and strongly supported populations: Isolates from China (IId) and Egypt (IIa and IId) formed population 1; a minority of European isolates (IIa and IId) formed population 2; and the majority of European (IIa, including all IIaA15G2R1 isolates) and all isolates from the United States (IIa) clustered in population 3. Based on analyses of the population structure, population genetics, and recombination, we show that population 3 has recently emerged and expanded throughout Europe to then, possibly from the United Kingdom, reach the United States, where it also expanded. The reason(s) for the successful spread of population 3 remain elusive, although genes under selective pressure uniquely in this population were identified.

Cryptosporidium spp. Infection and Genotype Identification in Pre-Weaned and Post-Weaned Calves in Yunnan Province, China

BACKGROUND

Cryptosporidium is a globally distributed zoonotic protozoan parasite in humans and animals. Infection is widespread in dairy cattle, especially in calves, resulting in neonatal enteritis, production losses and high mortality. However, the occurrence of Cryptosporidium spp. in pre- and post-weaned calves in Yunnan Province remains unclear.

METHODS

We collected 498 fecal samples from Holstein calves on 10 different farms in four regions of Yunnan Province. Nested PCR and DNA sequencing were used to determine the infection, species and genotypes of Cryptosporidium spp. in these animals.

RESULTS

The overall occurrence of Cryptosporidium spp. in Holstein calves was 32.9% (164/498), and the prevalence in pre- and post-weaned calves was 33.5% (106/316) and 31.9% (58/182), respectively. Four Cryptosporidium species were identified in these animals, namely C. bovis (n = 119), C. parvum (n = 23), C. ryanae (n = 20) and C. andersoni (n = 2). Based on sequencing analysis of the 60 kDa glycoprotein gene of C. bovis, C. parvum and C. ryanae, six subtypes of C. bovis (XXVIe, XXVIb, XXVIf, XXVIa XXVIc and XXVId), two subtypes of C. parvum (IIdA19G1 and IIdA18G1) and four subtypes of C. ryanae (XXIf, XXId, XXIe and XXIg) were identified.

CONCLUSIONS

These results provide essential information to understand the infection rate, species diversity and genetic structure of Cryptosporidium spp. populations in Holstein pre-weaned and post-weaned calves in Yunnan Province. Further, the presence of IIdA18G1 and IIdA19G1 in C. parvum implies significant animal and public health concerns, which requires greater attention and more preventive measures.

Earth at risk: An urgent call to end the age of destruction and forge a just and sustainable future

Human development has ushered in an era of converging crises: climate change, ecological destruction, disease, pollution, and socioeconomic inequality. This review synthesizes the breadth of these interwoven emergencies and underscores the urgent need for comprehensive, integrated action. Propelled by imperialism, extractive capitalism, and a surging population, we are speeding past Earth's material limits, destroying critical ecosystems, and triggering irreversible changes in biophysical systems that underpin the Holocene climatic stability which fostered human civilization. The consequences of these actions are disproportionately borne by vulnerable populations, further entrenching global inequities. Marine and terrestrial biomes face critical tipping points, while escalating challenges to food and water access foreshadow a bleak outlook for global security. Against this backdrop of Earth at risk, we call for a global response centered on urgent decarbonization, fostering reciprocity with nature, and implementing regenerative practices in natural resource management. We call for the elimination of detrimental subsidies, promotion of equitable human development, and transformative financial support for lower income nations. A critical paradigm shift must occur that replaces exploitative, wealth-oriented capitalism with an economic model that prioritizes sustainability, resilience, and justice. We advocate a global cultural shift that elevates kinship with nature and communal well-being, underpinned by the recognition of Earth's finite resources and the interconnectedness of its inhabitants. The imperative is clear: to navigate away from this precipice, we must collectively harness political will, economic resources, and societal values to steer toward a future where human progress does not come at the cost of ecological integrity and social equity.

Molecular characterization and zoonotic potential of Cryptosporidium spp. and Giardia duodenalis in humans and domestic animals in Heilongjiang Province, China

BACKGROUND

Cryptosporidiosis and giardiasis are significant parasitic diseases shared between humans and domestic animals. Due to the close contact between humans and domestic animals in rural areas, it is important to consider the potential transmission of zoonotic parasites from infected domestic animals to humans. This investigation aimed to determine the prevalence and molecular characteristics of Cryptosporidium spp. and Giardia duodenalis in domestic animals and villagers.

METHODS

A total of 116 fecal samples from villagers and 686 fecal samples from domestic animals in Heilongjiang Province, China, were analyzed for two parasites using nested polymerase chain reaction (PCR) targeting various genetic loci and DNA sequence analysis of the PCR products.

RESULTS

By sequence analysis of the SSU rRNA gene, the prevalence of Cryptosporidium in humans was 0.9% (1/116), with one species of C. parvum (n = 1) detected; among domestic animals, the prevalence was 2.6% (18/686), with five species identified: C. suis (n = 7) and C. scrofarum (n = 7) in pigs, C. meleagridis (n = 1) in chickens, C. andersoni (n = 1) in cattle, and C. canis (n = 2) in foxes. C. parvum and C. canis were further subtyped as IIdA19G1 and XXa4 on the basis of gp60 gene. Regarding G. duodenalis, based on the SSU rRNA, bg, gdh, and tpi genes, the prevalence in domestic animals was 5.1% (31/608), with three assemblages identified: A (n = 1) in pigs, D (n = 1) in foxes, and E (n = 27) in geese, cattle, pigs, ducks, and sheep, along with mixed infection of A + E (n = 1) in one pig and B + E (n = 1) in one sheep. No G. duodenalis was detected in humans (0/116).

CONCLUSIONS

The present results show that no overlap of subtypes between animals and villagers was found in Cryptosporidium spp. and G. duodenalis, indicating a minor role of domestic animals in infecting humans in this population. However, the presence of zoonotic protozoa in domestic animals highlights the need for special attention to high-risk individuals during close contact with domestic animals.

First report of Giardia duodenalis in dairy cattle and beef cattle in Shanxi, China

BACKGROUND

Giardia duodenalis is an important intestinal parasitic protozoan that infects several vertebrates, including humans. Cattle are considered the major source of giardiasis outbreak in humans. This study aimed to investigate the prevalence and multilocus genotype (MLG) of G. duodenalis in Shanxi, and lay the foundation for the prevention and control of Giardiosis.

METHODS AND RESULTS

DNA extraction, nested polymerase chain reaction, sequence analysis, MLG analysis, and statistical analysis were performed using 858 bovine fecal samples from Shanxi based on three gene loci: β-giardin (bg), glutamate dehydrogenase (gdh), and triosephosphate isomerase (tpi). The overall prevalence of G. duodenalis was 28.3%, while its prevalence in Yingxian and Lingqiu was 28.1% and 28.5%, respectively. The overall prevalence of G. duodenalis in dairy cattle and beef cattle was 28.0% and 28.5%, respectively. G. duodenalis infection was detected in all age groups evaluated in this study. The overall prevalence of G. duodenalis in diarrhea and nondiarrhea samples was 32.4% and 27.5%, respectively, whereas that in intensively farmed and free-range cattle was 35.0% and 19.9%, respectively. We obtained 83, 53, and 59 sequences of bg, gdh, and tpi in G. duodenalis, respectively. Moreover, assemblage A (n = 2) and assemblage E (n = 81) by bg, assemblage A (n = 1) and assemblage E (n = 52) by gdh, and assemblage A (n = 2) and assemblage E (n = 57) by tpi were identified. Multilocus genotyping yielded 29 assemblage E MLGs, which formed 10 subgroups.

CONCLUSIONS

To the best of our knowledge, this is the first study to report cattle infected with G. duodenalis in Shanxi, China. Livestock-specific G. duodenalis assemblage E was the dominant assemblage genotype, and zoonotic sub-assemblage AI was also detected in this region.

Respiratory exposure to agricultural dust extract promotes increased intestinal Tnfα expression, gut barrier dysfunction, and endotoxemia in mice

Concentrated animal feeding operations (CAFOs) are responsible for the production of global greenhouse gases and harmful environmental pollutants including hydrogen sulfide, ammonia, and particulate matter. Swine farmers are frequently exposed to organic dust that is proinflammatory in the lung and are thus at greater risk of developing pneumonia, asthma, and other respiratory conditions. In addition to respiratory disease, air pollutants are directly associated with altered gastrointestinal (GI) physiology and the development of GI diseases, thereby highlighting the gut-lung axis in disease progression. Instillation of hog dust extract (HDE) for 3 wk has been reported to promote the development of chronic airway inflammation in mice, however, the impact of HDE exposure on intestinal homeostasis is poorly understood. We report that 3-wk intranasal exposure of HDE is associated with increased intestinal macromolecule permeability and elevated serum endotoxin concentrations in C57BL/6J mice. In vivo studies also indicated mislocalization of the epithelial cell adhesion protein, E-cadherin, in the colon as well as an increase in the proinflammatory cytokine, Tnfα, in the proximal colon. Moreover, mRNA expression of the Paneth cell-associated marker, Lyz1, was increased the proximal colon, whereas the expression of the goblet cell marker, Muc2, was unchanged in the epithelial cells of the ileum, cecum, and distal colon. These results demonstrate that airway exposure to CAFOs dusts promote airway inflammation and modify the gastrointestinal tract to increase intestinal permeability, induce systemic endotoxemia, and promote intestinal inflammation. Therefore, this study identifies complex physiological consequences of chronic exposure to organic dusts derived from CAFOs on the gut-lung axis.NEW & NOTEWORTHY Agricultural workers have a higher prevalence of occupational respiratory symptoms and are at greater risk of developing respiratory diseases. However, gastrointestinal complications have also been reported, yet the intestinal pathophysiology is understudied. This work is novel because it emphasizes the role of an inhaled environmental pollutant on the development of intestinal pathophysiological outcomes. This work will provide foundation for other studies evaluating how agricultural dusts disrupts host physiology and promotes debilitating gastrointestinal and systemic disorders.

Prevalence, risk factors and molecular epidemiology of neonatal cryptosporidiosis in calves: The Argentine perspective

Cryptosporidium spp. are enteroparasitic protozoans that cause cryptosporidiosis in newborn calves. Clinical signs of the infection are diarrhoea and dehydration leading to decreased productivity and economic losses in cattle farms around the world. Additionally, cryptosporidiosis is a relevant zoonotic disease since the ingestion of oocysts can be fatal for children under five years of age, the elderly, and/or immunocompromised adults. This review aims to integrate existing knowledge on the epidemiological situation of calf cryptosporidiosis and associated risk factors in Argentina. In addition, the GP60 subtype diversity of the pathogen was analysed and related with the global distribution of corresponding GP60 subtypes. Depending on the study region and applied diagnostics, prevalence among calves up to 20 days of age varied between 25.2% and 42.5%, while a prevalence of 16.3-25.5% was observed at the age of 1-90 days. So far, molecular studies have determined exclusively Cryptosporidium parvum in preweaned calves. In addition, C. parvum infection was reported as the major cause of calf diarrhoea, followed by rotavirus A (RVA), while enteropathogens such as coronavirus, Escherichiacoli, and Salmonella sp. played a negligible role. Calf age of 20 days or less, incidence of diarrhoea, poorly drained soils, and large farm size were identified as risk factors for C. parvum-infection in Argentina. A total of nine GP60 subtypes (IIaAxxG1R1, xx = 16 to 24) were identified, showing a stepwise increase of the trinucleotide motif TCA, and including the zoonotic subtypes IIaA16G1R1, IIaA17G1R1, IIaA18G1R1, IIaA19G1R1, and IIaA20G1R1. We found that an increase in the A16→A24 trinucleotide repeat was accompanied by a gradual decrease in the global distribution of GP60 alleles, strongly suggesting that IIaA16G1R1 represents the primordial allelic variant of this group. Since identified GP60 alleles have a similar genetic background, we hypothesize that the continuous trinucleotide repeat array has been generated by stepwise repeat expansion of A16. The information gathered and integrated in this study contributes to an improved understanding of the epidemiological characteristics of bovine cryptosporidiosis in and beyond Argentina, which in turn can help to develop control strategies for this parasitosis of veterinary and medical relevance.

Cryptosporidium parvum and gp60 genotype prevalence in dairy calves worldwide: a systematic review and meta-analysis

Cryptosporidium is a significant zoonotic pathogen that often occurs in dairy cattle. We conducted a systematic review and meta-analysis of the prevalence of Cryptosporidium parvum infection in dairy calves worldwide to help improve global animal husbandry and public policy implementation. Published articles were obtained from PubMed and Web of Science from January 1, 2000 to December 31, 2021. The prevalence of C. parvum infection in dairy calves was estimated using a random effects model, and the sources of heterogeneity were explored using meta-regression. In total, 118 datasets were included in the final quantitative analysis. The results showed that the global prevalence of C. parvum in dairy calves was 21.9% (7755/42,890; 95% confidence interval: 19.9-23.9%). C. parvum infection was high in pre-weaned dairy calves (24.9%, 6706/29,753) and diarrhea dairy calves (33.6%, 1637/6077). In countries with low dairy stocking density (<10 cows/farm), the prevalence of C. parvum in dairy calves was also relatively low (15.2%, 1960/16,584). Three subtype families [IIa (72.2%, 2293/3177), IId (27.4%, 872/3177), and IIl (0.4%, 12/3177)] were detected in dairy calves globally from selected studies. C. parvum IIa was the dominant zoonotic subtype. In the IIa subtype family of C. parvum, the proportions of subtypes from high to low (top nine) were IIaA15G2R1 (32.4%, 742/2293), IIaA18G3R1 (11.8%, 271/2293), IIaA13G2R1 (8.2%, 187/2293), IIaA16G1R1 (6.4%, 147/2293), IIaA20G1R1 (3.5%, 81/2293), IIaA16G3R1 (3.4%, 78/2293), IIaA17G2R1 (2.7%, 62/2293), IIaA18G1R1 (2.5%, 58/2293), and IIaA15G1R1 (2.4%, 56/2293). In the IId subtype family of C. parvum, the proportions of subtypes (top four) were IIdA19G1 (36.0%, 314/872), IIdA15G1 (27.3%, 238/872), IIdA20G1 (16.2%, 141/872), and IIdA14G1 (13.0%, 113/872). Furthermore, IId is commonly found in China (771/872). The study results indicated that the IIa subtype family is globally prevalent, while IId is found in Asia, Europe, and Africa and IIl is only found in Europe. Diarrhea in dairy calves is associated with C. parvum infection and a significantly higher prevalence is observed in diarrheic calves. Age and stock density are two significant risk factors in the prevalence of C. parvum in dairy calves. The prevention and control of this zoonosis in dairy calves should receive greater attention, especially in regions with a high degree of intensive dairy farming.

Sympatric Recombination in Zoonotic Cryptosporidium Leads to Emergence of Populations with Modified Host Preference

Genetic recombination plays a critical role in the emergence of pathogens with phenotypes such as drug resistance, virulence, and host adaptation. Here, we tested the hypothesis that recombination between sympatric ancestral populations leads to the emergence of divergent variants of the zoonotic parasite Cryptosporidium parvum with modified host ranges. Comparative genomic analyses of 101 isolates have identified seven subpopulations isolated by distance. They appear to be descendants of two ancestral populations, IIa in northwestern Europe and IId from southwestern Asia. Sympatric recombination in areas with both ancestral subtypes and subsequent selective sweeps have led to the emergence of new subpopulations with mosaic genomes and modified host preference. Subtelomeric genes could be involved in the adaptive selection of subpopulations, while copy number variations of genes encoding invasion-associated proteins are potentially associated with modified host ranges. These observations reveal ancestral origins of zoonotic C. parvum and suggest that pathogen import through modern animal farming might promote the emergence of divergent subpopulations of C. parvum with modified host preference.

Occurrence and Molecular Characterization of Cryptosporidium spp. in Dairy Cattle and Dairy Buffalo in Yunnan Province, Southwest China

Simple Summary

Cryptosporidium spp. are important gastrointestinal pathogens of humans and animals, causing diarrheal diseases. Cattle are considered as one of the main reservoirs of Cryptosporidium for humans. We first report the occurrence of Cryptosporidium spp. in dairy cattle (14.7%, 65/442) and dairy buffalo (1.1%, 3/258) in Yunnan Province of China. The results of this study suggest that divergent Cryptosporidium spp. (such as C. andersoni, C. bovis, C. ryanae, and C. parvum) can be found in asymptomatic dairy cattle and dairy buffalo in Yunnan, China. The IIdA18G1 subtype of C. parvum, which infects humans and other animals, was also found in this study. Thus, attention should be paid towards preventing the transmission of Cryptosporidium spp. in cattle and humans in Yunnan Province.

Abstract

Cryptosporidium spp. are important foodborne and waterborne pathogens in humans and animals, causing diarrheal diseases. Cattle are one of the reservoirs of Cryptosporidium infection in humans. However, data on the occurrence of Cryptosporidium spp. in cattle in Yunnan Province remains limited. A total of 700 fecal samples were collected from Holstein cows (n = 442) and dairy buffaloes (n = 258) in six counties of Yunnan Province. The occurrence and genotypes of Cryptosporidium spp. were analyzed using nested PCR and DNA sequencing. Furthermore, the C. andersoni isolates were further analyzed using multilocus sequence typing (MLST) at four gene loci (MS1, MS2, MS3, and MS16), and the C. parvum isolate was subtyped by 60-kDa glycoprotein (gp60) loci. The occurrence of Cryptosporidium spp. in Holstein cows and dairy buffaloes was 14.7% (65/442) and 1.1% (3/258), respectively. Of these positive samples, 56 Holstein cow samples represented C. andersoni, four Holstein cow samples represented C. bovis, three Holstein cow samples represented C. ryanae, and one represented C. parvum. Meanwhile, only three dairy buffalo samples represented C. ryanae. MLST analysis of subtypes of C. andersoni detected four subtypes, including A5A4A2A1 (n = 7), A4A4A4A1 (n = 7), A1A4A4A1 (n = 2), and A4A4A2A1 (n = 1). One C. parvum isolate was identified as the IIdA18G1 subtype. These results revealed the high occurrence and high genetic diversity of Cryptosporidium spp. in Holstein cows in Yunnan Province, enriching the knowledge of the population genetic structure of Cryptosporidium spp. in Yunnan Province.

Avian Pathogens: Editorial and the Perspectives of Research

In the last ten years, humanity has faced new challenges in the field of human and animal health, including emerging viral infections [...].