Seasonal Pattern Of Infection Research Articles

New insights into honey bee viral and bacterial seasonal infection patterns using third-generation nanopore sequencing on honey bee haemolymph

Honey bees are rapidly declining, which poses a significant threat to our environment and agriculture industry. These vital insects face a disease complex believed to be caused by a combination of parasites, viruses, pesticides, and nutritional deficiencies. However, the real aetiology is still enigmatic. Due to the conventional analysis methods, we still lack complete insights into the honey bee virome and the presence of pathogenic bacteria. To fill this knowledge gap, we employed third-generation nanopore metagenomic sequencing on honey bee haemolymph to monitor the presence of pathogens over almost a year. This study provides valuable insights into the changes in bacterial and viral loads within honey bee colonies. We identified different pathogens in the honey bee haemolymph, which are not included in honey bee screenings. These pathogens comprise the Apis mellifera filamentous virus, Apis rhabdoviruses, and various bacteria such as Frischella sp. and Arsenophonus sp. Furthermore, a sharp contrast was observed between young and old bees. Our research proposes that transgenerational immune priming may play a role in shaping infection patterns in honey bees. We observed a significant increase in pathogen loads in the spring, followed by a notable decrease in pathogen presence during the summer and autumn months. However, certain pathogens seem to be able to evade this priming effect, making them particularly intriguing as potential factors contributing to mortality. In the future, we aim to expand our research on honey bee transgenerational immune priming and investigate its potential in natural settings. This knowledge will ultimately enhance honey bee health and decrease colony mortality.

The Scope of Respiratory Syncytial Virus Infection in a Tertiary Hospital in the Eastern Province of Saudi Arabia and the Change in Seasonal Pattern during and after the COVID-19 Pandemic.

Background and Objectives: Respiratory syncytial virus (RSV) is a major cause of morbidity and hospital admission due to respiratory tract infection among infants and young children. The current study aims to describe the prevalence and the seasonal pattern of RSV during the previous seven years. Materials and Methods: Clinical data and RSV antigen and PCR test results were collected from patients' medical records at King Fahd Hospital of the University in the Eastern Province of Saudi Arabia between January 2015 and February 2022. Results: The overall percentage of RSV detection was 26.3% (336/1279) among the tested individuals. RSV infection was more common among children below five years and elderly above 60 years of age. Two-thirds of the cases required hospitalization. The average hospital stay due to RSV infection was 6.5 days (range 0-56 days). The rate of hospitalization was higher among infants and younger children and decreased with age (p-value < 0.001). RSV infection was more prevalent between August and February and decreased appreciably between March and July. The peak level of infection was during December and January. No RSV infections were reported during the COVID-19 pandemic and the following winter. The cases increased again in August 2021, with an unusual out-of-season peak. Conclusions: RSV infection is one of the important causes of morbidity and hospitalization among infants and young children in Saudi Arabia. The seasonal pattern of infection has changed after the COVID-19 pandemic, and the physicians should be aware that infection may happen currently at different times throughout the year.

Estimation of R0 for the spread of SARS-CoV-2 in Germany from excess mortality

For SARS-CoV-2, R0 calculations in the range of 2–3 dominate the literature, but much higher estimates have also been published. Because capacity for RT-PCR testing increased greatly in the early phase of the Covid-19 pandemic, R0 determinations based on these incidence values are subject to strong bias. We propose to use Covid-19-induced excess mortality to determine R0 regardless of RT-PCR testing capacity. We used data from the Robert Koch Institute (RKI) on the incidence of Covid cases, Covid-related deaths, number of RT-PCR tests performed, and excess mortality calculated from data from the Federal Statistical Office in Germany. We determined R0 using exponential growth estimates with a serial interval of 4.7 days. We used only datasets that were not yet under the influence of policy measures (e.g., lockdowns or school closures). The uncorrected R0 value for the spread of SARS-CoV-2 based on RT-PCR incidence data was 2.56 (95% CI 2.52–2.60) for Covid-19 cases and 2.03 (95% CI 1.96–2.10) for Covid-19-related deaths. However, because the number of RT-PCR tests increased by a growth factor of 1.381 during the same period, these R0 values must be corrected accordingly (R0corrected = R0uncorrected/1.381), yielding 1.86 for Covid-19 cases and 1.47 for Covid-19 deaths. The R0 value based on excess deaths was calculated to be 1.34 (95% CI 1.32–1.37). A sine-function-based adjustment for seasonal effects of 40% corresponds to a maximum value of R0January = 1.68 and a minimum value of R0July = 1.01. Our calculations show an R0 that is much lower than previously thought. This relatively low range of R0 fits very well with the observed seasonal pattern of infection across Europe in 2020 and 2021, including the emergence of more contagious escape variants such as delta or omicron. In general, our study shows that excess mortality can be used as a reliable surrogate to determine the R0 in pandemic situations.

Seasonality of host immunity in a tropical disease system

AbstractInfectious disease systems frequently exhibit strong seasonal patterns, yet the mechanisms that underpin intra‐annual cycles are unclear, particularly in tropical regions. We hypothesized that host immune function fluctuates seasonally, contributing to oscillations in infection patterns in a tropical disease system. To test this hypothesis, we investigated a key host defense of amphibians against a lethal fungal pathogen, Batrachochytrium dendrobatidis (Bd). We integrated two field experiments in which we perturbed amphibian skin secretions, a critical host immune mechanism, in Panamanian rocket frogs (Colostethus panamansis). We found that this immunosuppressive technique of reducing skin secretions in wild frog populations increased Bd prevalence and infection intensity, indicating that this immune defense contributes to resistance to Bd in wild frog populations. We also found that the chemical composition and anti‐Bd effectiveness of frog skin secretions varied across seasons, with greater pathogen inhibition during the dry season relative to the wet season. These results suggest that the effectiveness of this host defense mechanism shifts across seasons, likely contributing to seasonal infection patterns in a lethal disease system. More broadly, our findings indicate that host immune defenses can fluctuate across seasons, even in tropical regions where temperatures are relatively stable, which advances our understanding of intra‐annual cycles of infectious disease dynamics.

Prevalence of Protozoan Parasites Cryptosporidium sp. and Callimastix equi in the Edible Oyster Saccostrea cucullata and Its Relationship with Selected Water Quality Parameters in Sundarbans Region of West Bengal, India.

Prevalence of protozoan parasites Cryptosporidium sp. and Callimastix equi in the edible oyster resources Saccostrea cucullata, and its relationship with selected water quality parameters such as temperature, pH and salinity in Sundarbans region of West Bengal, India, have been assessed and discussed elaborately. Edible oysters S. cucullata were collected randomly from the selected study site Frasergunj of Sundarbans region and protozoan parasites such as Cryptosporidium sp. and C. equi were isolated, stained and determined its prevalence. Relationship of water temperature, pH and salinity with the prevalence of protozoan parasite had been assessed and analyzed. Prevalence of infection of Cryptosporidium sp. is much more than the C. equi found in S. cucullata. The infections of the parasites are higher during monsoon then pre-monsoon season. Significant negative correlation (P < 0.05) occurs between pH of water and prevalence of Cryptosporidium sp. and C. equi in the edible oyster S. cucullata collected from Frasergunj of Sundarbans region, South 24 Parganas of West Bengal. The C. equi parasite follows a seasonal pattern of infection varying significantly with salinity (P < 0.01) of the water in the edible oyster, S. cucullata collected from Frasergunj of South 24 Parganas of West Bengal. These results indicate that the Cryptosporidium sp. and C. equi contamination is accompanying with public health risks if edible oysters are consumed uncooked of undercooked. Extremes and/or rapid fluctuations of important environmental factors such as water temperature, salinity, pH can seriously compromise oyster health and outcome of aquaculture.

Seasonal patterns of malaria, genital infection, nutritional and iron status in non-pregnant and pregnant adolescents in Burkina Faso: a secondary analysis of trial data

BackgroundAdolescents are considered at high risk of developing iron deficiency. Studies in children indicate that the prevalence of iron deficiency increased with malaria transmission, suggesting malaria seasonally may drive iron deficiency. This paper examines monthly seasonal infection patterns of malaria, abnormal vaginal flora, chorioamnionitis, antibiotic and antimalarial prescriptions, in relation to changes in iron biomarkers and nutritional indices in adolescents living in a rural area of Burkina Faso, in order to assess the requirement for seasonal infection control and nutrition interventions.MethodsData collected between April 2011 and January 2014 were available for an observational seasonal analysis, comprising scheduled visits for 1949 non-pregnant adolescents (≤19 years), (315 of whom subsequently became pregnant), enrolled in a randomised trial of periconceptional iron supplementation. Data from trial arms were combined. Body Iron Stores (BIS) were calculated using an internal regression for ferritin to allow for inflammation. At recruitment 11% had low BIS (< 0 mg/kg). Continuous outcomes were fitted to a mixed-effects linear model with month, age and pregnancy status as fixed effect covariates and woman as a random effect. Dichotomous infection outcomes were fitted with analogous logistic regression models.ResultsSeasonal variation in malaria parasitaemia prevalence ranged between 18 and 70% in non-pregnant adolescents (P < 0.001), peaking at 81% in those who became pregnant. Seasonal variation occurred in antibiotic prescription rates (0.7–1.8 prescriptions/100 weekly visits, P < 0.001) and chorioamnionitis prevalence (range 15–68%, P = 0.026). Mucosal vaginal lactoferrin concentration was lower at the end of the wet season (range 2–22 μg/ml, P < 0.016), when chorioamnionitis was least frequent. BIS fluctuated annually by up to 53.2% per year around the mean BIS (5.1 mg/kg2, range 4.1–6.8 mg/kg), with low BIS (< 0 mg/kg) of 8.7% in the dry and 9.8% in the wet seasons (P = 0.36). Median serum transferrin receptor increased during the wet season (P < 0.001). Higher hepcidin concentration in the wet season corresponded with rising malaria prevalence and use of prescriptions, but with no change in BIS. Mean Body Mass Index and Mid-Upper-Arm-Circumference values peaked mid-dry season (both P < 0.001).ConclusionsOur analysis supports preventive treatment of malaria among adolescents 15–19 years to decrease their disease burden, especially asymptomatic malaria. As BIS were adequate in most adolescents despite seasonal malaria, a requirement for programmatic iron supplementation was not substantiated.

Factors associated with small lungworm infections in heavily infected sheep in southeast South Australia

This field observational study describes the seasonal pattern of small lungworm infections under different grazing managements from August 2018 to March 2019. Live weight, lungworm and gastrointestinal nematode infection, as well as pasture type grazed and snail density, were measured at 5 farm visits. Across all visits and mobs, about one quarter to one half of sheep were positive for small lungworm, although prevalence was as low as 0% and as high as 78%. The density of the intermediate host molluscs was greater than 1600 snails/m2 in irrigated perennial lucerne pasture when it was grazed ('Pasture A'), but was low (<300) in non-irrigated perennial pasture ('Pasture B') and non-irrigated forage crop ('Pasture C'). Overall, non-infected lambs had a similar live weight compared with the small lungworm infected lambs (mean difference -0.6 kg; 95% CI -1.6 to 0.2; P=0.1). The odds ratio of small lungworm infection associated with a twofold increase in worm egg count was 1.7 (95% CI 1.1 to 2.7; P=0.02). Rather than a distinct seasonal pattern of infection, we found that small lungworm can occur throughout the year, with prevalence most influenced by pasture type (irrigated vs dryland), grazing management and the population density of the intermediate hosts. Importantly, this study suggested that small lungworm infection did not reduce lamb live weights. It reinforced that to improve sheep productivity, well-established determinants of production, such as correct grazing management to optimise pasture quality and strategies to reduce infections with gastrointestinal nematodes, should be the priority of farm managers.

Anthelmintic resistance and prevalence of gastrointestinal nematodes infecting sheep in Limpopo Province, South Africa

Background and Aim:Previous studies recorded the prevalence of gastrointestinal nematodes (GIN) in Limpopo Province. However, the studies did not address the seasonal patterns of infection and did not cover all districts of Limpopo Province, namely; Capricorn, Sekhukhune, Waterberg, Mopani, and Vhembe. It is, therefore, important to provide up to date information on the prevalence and seasonal occurrence data of GIN in all districts of Limpopo province. The present study was conducted to determine the occurrence of anthelmintic resistance (AR) and document the prevalence of GIN infecting sheep in five districts of Limpopo Province, South Africa.Materials and Methods:Forty animals in each district were used for fecal egg count reduction test (FECRT) to determine AR against ivermectin (0.2 mg/kg), levamisole (LEV) (5 mg/kg), and albendazole (7.5 mg/kg). Egg hatch test (EHT) was used to determine AR against thiabendazole (TBZ) and micro-agar larval development test (MALDT) was used for both TBZ and LEV. Naturally, infected sheep (n=780) were sampled for prevalence across five districts of Limpopo. FAMACHA© eye-color score estimations were also performed for each study animal.Results:FECRT showed occurrence of AR in most of the districts and a few with suspected resistance. EHT results showed AR development against TBZ for all districts, while the MALDT showed no AR against LEV in all districts, but detected AR against TBZ in Sekhukhune, Capricorn, and Waterberg. Haemonchus contortus was the most resistant species. A high nematode prevalence (88-100%) and 1210-1861 eggs per gram (EPG) was observed in all districts during the hot wet season, decreasing to 75-80% (453-1202 EPG) during the cold dry season. The sheep revealed a FAMACHA© mean score of 3, indicating mild anemia during the hot wet season except for Vhembe district that revealed a FAMACHA© mean score of 4 during the hot wet season, indicating anemia.Conclusion:AR recorded in Limpopo Province may be due to under-dosing caused by lack of weighing equipment and high treatment frequencies due to lack of proper training on anthelmintic use. The detection of AR in Limpopo is an important finding because it will help in outlining effective management systems against GIN.

Molecular epidemiologic trends of norovirus and rotavirus infection and relation with climate factors: Cheonan, Korea, 2010-2019

Background: Viral infection outbreaks are emerging public health concerns. They often exhibit seasonal patterns that could be predicted by the application of big data and bioinformatic analyses. Purpose: The purpose of this study was to identify trends in diarrhea-causing viruses such as rotavirus (Gr.A), norovirus G-I, and norovirus G-II in Cheonan, Korea. The identified related factors of diarrhea-causing viruses may be used to predict their trend and prevent their infections. Method: A retrospective analysis of 4,009 fecal samples from June 2010 to December 2019 was carried out at Dankook University Hospital in Cheonan. Reverse transcription-PCR (RT-PCR) was employed to identify virus strains. Information about seasonal patterns of infection was extracted and compared with local weather data. Results: Out of the 4,009 fecal samples tested using multiplex RT-PCR (mRT-PCR), 985 were positive for infection with Gr.A, G-I, and G-II. Out of these 985 cases, 95.3% (n = 939) were under 10 years of age. Gr.A, G-I, and G-II showed high infection rates in patients under 10 years of age. Student's t-test showed a significant correlation between the detection rate of Gr.A and the relative humidity. The detection rate of G-II significantly correlated with wind-chill temperature. Conclusion: Climate factors differentially modulate rotavirus and norovirus infection patterns. These observations provide novel insights into the seasonal impact on the pathogenesis of Gr.A, G-I, and G-II.

Seasonal prevalence of the amphibian chytrid in a tropical pond-dwelling tadpole species.

Infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd) is a major threat to amphibians and has caused catastrophic global declines of amphibian populations. Some studies have detected a seasonal pattern of infection associated with the local climate, and although most of them have focused on investigating the seasonality of Bd in relation to its impacts on amphibians, fewer have aimed to understand the chytrid persistence in the amphibian assemblage over seasons by investigating reservoir hosts. Since tadpoles are generally tolerant to Bd infection, they often play a relevant role in local disease dynamics. Thus, we hypothesized that tadpoles of Boana faber, a species that can be found in permanent ponds throughout the seasons, would function as Bd reservoirs. We therefore investigated Bd infection prevalence in tadpoles of this species over 2 yr in a nature reserve. As expected, we detected a seasonal variation of Bd infection, with a higher prevalence of Bd during the coldest months (winter) when compared to the warmer months (summer). Interestingly, our seasonal-trend decomposition analysis showed that Bd prevalence is increasing annually in the area, which could represent either a natural fluctuation of this pathogen, or an imminent threat to that anuran assemblage. With this study, we highlight the tadpole of B. faber as a potential reservoir for Bd, and we suggest that monitoring Bd in such hosts could be a powerful tool for identifying priority areas for amphibian conservation.

Persistence of avian haemosporidians in the wild: a case study to illustrate seasonal infection patterns in relation to host life stages

Infection patterns of avian haemosporidians result from the evolution of their associations with hosts, and can be shaped by multiple biotic factors. However, at the level of parasite species, few studies have investigated the details of the temporal dynamics of infection patterns in wild bird communities. We hereby studied a wild bird community in southern Sweden to investigate two generalist parasites (cyt b lineages PARUS1 and WW2) of the morphological species Haemoproteus majoris in their main host species (tits and warblers, respectively) to look for seasonal (spring to autumn) and age class related variation in infection patterns. For both lineages, we detected a similar temporal pattern in prevalence and infection intensity, with peak levels during the main nesting season in adults and a few weeks later in juveniles. Infections in juveniles were detected as soon as they started to be caught by mist nets, implying that they became infected when still in the nest or during the first weeks post-fledging. The initially high intensities in juveniles were followed by a significant decrease during the hatching year, emphasising the importance of studying haemosporidian infections in nestlings and fledglings. Both prevalence and infection intensity in adults increased from spring to early summer, either due to spring relapses or new infections. Both prevalence and infection intensity declined in adults at the time when independent juveniles of the respective species started to appear, suggesting that the rate of parasite withdrawal from blood exceeded the rates of new infections gained and relapses of previous infections. Prevalence in both juveniles and adults approached zero towards the end of the summer.

Impact of weather variables and season on sporulation of Phytophthora pluvialis and Phytophthora kernoviae

AbstractPhytophthora pluvialis and Phytophthora kernoviae are the causal agents of important needle diseases on Pinus radiata in New Zealand. Little is known about the epidemiology of the diseases, making the development of control strategies challenging. To investigate the seasonality and climatic drivers of sporulation, inoculum traps, consisting of pine fascicles floating on water in plastic containers, were exchanged fortnightly at five sites in P. radiata plantations between February 2012 and December 2014. Sections of needle baits were plated onto selective media and growth of Phytophthora pluvialis and P. kernoviae recorded. To explore the generalizability of these data, they were compared to detection data for both pathogens from the New Zealand Forest Health Database (NZFHDB). Further, equivalent analyses on infection of Rhododendron ponticum by P. kernoviae in Cornwall, UK allowed the comparison of the epidemiology of P. kernoviae across different host systems and environments. In New Zealand, inoculum of P. pluvialis and P. kernoviae was detected between January–December and March–November, respectively. Inoculum of both species peaked in abundance in late winter. The probability of detecting P. pluvialis and P. kernoviae was greater at lower temperatures, while the probability of detecting P. pluvialis also increased during periods of wet weather. Similar patterns were observed in NZFHDB data. However, the seasonal pattern of infection by P. kernoviae in the UK was the opposite of that seen for sporulation in New Zealand. Phytophthora kernoviae was likely limited by warmer and drier summers in New Zealand, but by colder winter weather in the UK. These results emphasize the importance of considering both environmental drivers and thresholds in improving our understanding of pathogen epidemiology.

COVID-19: relationship between atmospheric temperature and daily new cases growth rate.

Purpose: The novel coronavirus (severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)) first appeared in Wuhan, China, in December 2019, and rapidly spread across the globe. Since most respiratory viruses are known to show a seasonal pattern of infection, it has been hypothesised that SARS-CoV-2 may be seasonally dependent as well. The present study looks at a possible effect of atmospheric temperature, which is one of the suspected factors influencing seasonality, on the evolution of the pandemic. Basic procedures: Since confirming a seasonal pattern would take several more months of observation, we conducted an innovative day-to-day micro-correlation analysis of nine outbreak locations, across four continents and both hemispheres, in order to examine a possible relationship between atmospheric temperature (used as a proxy for seasonality) and outbreak progression. Main findings: There was a negative correlation between atmospheric temperature variations and daily new cases growth rates, in all nine outbreaks, with a median lag of 10 days. Principal conclusions: The results presented here suggest that high temperatures might dampen SARS-CoV-2 propagation, while lower temperatures might increase its transmission. Our hypothesis is that this could support a potential effect of atmospheric temperature on coronavirus disease progression, and potentially a seasonal pattern for this virus, with a peak in the cold season and rarer occurrences in the summer. This could guide government policy in both the Northern and Southern hemispheres for the months to come.

Seasonality of skipjack tuna parasites in the Eastern Atlantic provide an insight into its migratory patterns

A sample of 128 skipjack tuna Katsuwonus pelamis from Madeira archipelago was the subject of a parasitological analysis, in order to identify seasonal patterns of parasite infection which can provide information regarding the migratory patterns of skipjack tuna in the Eastern Atlantic. A total of 24 parasite taxa were detected. The nematode Oncophora melanocephala (Nematoda: Camallanidae) was identified as a first record for the genus Katsuwonus and several species were detected for the first time in the Eastern Atlantic, including the didymozoid trematode Pozdnyakovia gibsoni (Trematoda: Didymozoidae), originally described in skipjack tuna from Brazil. Generalized Linear Modelling (GLM) analysis revealed season and host fork length as the main predictors of parasite abundance, uncovering seasonal patterns of infection that indicate that migration to waters around Madeira occurs in at least two separate stages, and suggests a mixing of skipjack tuna sub-populations from both sides of the Atlantic.

Lungworm in cattle: epidemiology, pathology and immunobiology

The bovine lungworm, Dictyocaulus viviparus, causes disease in all ages of cattle and in addition to having a self-evident effect on animal welfare, it can have a considerable economic impact at farm level, even with subclinical infections. While most clinical cases are seen in cattle at pasture from July until housing, occasional outbreaks occur in housed cattle that have been infected previously at grass, or occasionally from infections acquired from forage or low-level cycling in straw yards. While the overall seasonal pattern of infection is consistent over large temporal and spatial scales, there is marked year-to-year and within season variability in the number of cases seen at both regional and farm levels. This relative unpredictability can bring uncertainty to decisions on control. In order to be able to provide sound, evidence-based advice on treatment and control to farmers, it is important that clinicians grasp important, practically relevant aspects of lungworm biology, pathology, immunity and epidemiology: the aim of this article is to do just that. A second article describes and analyses the options for prevention and treatment of husk, based on this knowledge.

Overlap in the Seasonal Infection Patterns of Avian Malaria Parasites and West Nile Virus in Vectors and Hosts.

Multiple vector-borne pathogens often circulate in the same vector and host communities, and seasonal infection dynamics influence the potential for pathogen interactions. Here, we explore the seasonal infection patterns of avian malaria (Haemosporida) parasites (Plasmodium and Haemoproteus) and West Nile virus (WNV) in birds and mosquitoes in suburban Chicago. We show that both pathogens vary seasonally in Culex mosquitoes and avian hosts, but that patterns of covariation are complex. Different putative Plasmodium species varied asynchronously across the season in mosquitoes and birds, suggesting that different forces may govern their transmission. Infections of Culex mosquitoes with Plasmodium parasites were positively associated with WNV infections in pools of individuals aggregated from the same time and site, suggesting that these pathogens respond to common environmental drivers and co-circulate among the same host and vector populations. Future research should focus on these common drivers, and whether these pathogens interact in vectors and hosts.

Capturing individual‐level parameters of influenza A virus dynamics in wild ducks using multistate models

SummaryDisease prevalence in wildlife is governed by epidemiological parameters (infection and recovery rates) and response to infection, both of which vary within and among individual hosts. Studies quantifying these individual‐scale parameters and documenting their source of variation in wild hosts are fundamental for predicting disease dynamics. Such studies do not exist for the influenza A virus (IAV), despite its strong impact on the global economy and public health.Using capture–recaptures of 3500 individual mallardsAnas platyrhynchosduring seven migration seasons at a stopover site in southern Sweden, we provide the first empirical description of the individual‐based mechanisms ofIAVdynamics in a wild reservoir host.For most years, prevalence and risk ofIAVinfection peaked at a single time during the autumn migration season, but the timing, shape and intensity of the infection curve showed strong annual heterogeneity. In contrast, the seasonal pattern of recovery rate only varied in intensity across years.Adults and juveniles displayed similar seasonal patterns of infection and recovery each year. However, compared to adults, juveniles experienced twice the risk of becoming infected, whereas recovery rates were similar across age categories. Finally, we did not find evidence that infection influenced the timing of emigration.Synthesis and applications. Our study provides robust empirical estimates of epidemiological parameters for predicting influenza A virus (IAV) dynamics. However, the strong annual variation in infection curves makes forecasting difficult. Prevalence data can provide reliable surveillance indicators as long as they catch the variation in infection risk. However, individual‐based monitoring of infection is required to verify this assumption in areas where surveillance occurs. In this context, monitoring of captive sentinel birds kept in close contact with wild birds is useful. The fact that infection does not impact the timing of migration underpins the potential for mallards to spread viruses rapidly over large geographical scales. Hence, we strongly encourageIAVsurveillance with a multistate capture–recapture approach along the entire migratory flyway of mallards.

Finding refuge: The estuarine distribution of the nemertean egg predator Carcinonemertes errans on the Dungeness crab, Cancer magister

Parasites can significantly impact ecosystems by altering the distributions and population sizes of their host organisms. Some hosts are thought to find refuge from parasitism by entering habitats where their parasites cannot survive. The nemertean worm Carcinonemertes errans is an egg predator that infects the Dungeness crab, Cancer magister, throughout the host's range. To determine if C. magister experiences a refuge from C. errans within estuarine environments, we examined the distribution of C. errans on Dungeness crabs within Oregon's Coos Bay Estuary. Year-round sampling over a three-year period also allowed us to test for temporal variation in the parasite's distribution. We found that parasite prevalence, mean intensity, and parasite density of C. errans infecting C. magister varied along a clear estuarine gradient, with crabs nearest the ocean carrying the heaviest parasite loads. Larger crabs were more heavily infected with worms, and seasonal infection patterns were observed at some sites within the bay. Crabs sampled from coastal waters near the estuary carried significantly more worms than did crabs from the bay, suggesting that the estuary is acting as a spatiotemporal parasite refuge for this important fishery species.

Climate and the epidemiology of gastrointestinal nematode infections of sheep in Europe

The free-living stages of gastrointestinal nematode parasites of sheep are strongly affected by climate. Thus, extreme heat and cold are detrimental to development and survival, while, within tolerable limits, increasing temperatures generally accelerate development but increase mortality. Moisture is needed for development and translation of larvae from faeces to pasture, and so rainfall is a limiting factor for transmission. Together, these factors underpin seasonal patterns of infection in sheep, as well as geographic variation in the epidemiology and relative importance of different species within Europe. Local knowledge and experience enable treatment to be targeted appropriately to prevent dangerous levels of infection. This traditional know-how can be supplemented by predictive epidemiological models, built on thorough understanding of the influence of climate on larval availability. However, management also has a dominant role in determining patterns of infection, and is itself influenced by climate. Current geographic variation in nematode epidemiology across Europe, and knowledge of systems from outside Europe, can provide only limited perspectives on the likely effects of climate change on disease in future. This is because disease arises from complex interaction between host and parasite factors, and the implementation of optimal control strategies to meet new challenges will be slowed by the inertia of current systems. Approaches to nematode control must therefore take account not only of parasite biology, but also the forces that shape sheep farming systems and management decisions.

Variability and Diversity of Nasopharyngeal Microbiota in Children: A Metagenomic Analysis

The nasopharynx is the ecological niche for many commensal bacteria and for potential respiratory or invasive pathogens like Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. Disturbance of a balanced nasopharyngeal (NP) microbiome might be involved in the onset of symptomatic infections with these pathogens, which occurs primarily in fall and winter. It is unknown whether seasonal infection patterns are associated with concomitant changes in NP microbiota. As young children are generally prone to respiratory and invasive infections, we characterized the NP microbiota of 96 healthy children by barcoded pyrosequencing of the V5–V6 hypervariable region of the 16S-rRNA gene, and compared microbiota composition between children sampled in winter/fall with children sampled in spring. The approximately 1000000 sequences generated represented 13 taxonomic phyla and approximately 250 species-level phyla types (OTUs). The 5 most predominant phyla were Proteobacteria (64%), Firmicutes (21%), Bacteroidetes (11%), Actinobacteria (3%) and Fusobacteria (1,4%) with Moraxella, Haemophilus, Streptococcus, Flavobacteria, Dolosigranulum, Corynebacterium and Neisseria as predominant genera. The inter-individual variability was that high that on OTU level a core microbiome could not be defined. Microbiota profiles varied strongly with season, with in fall/winter a predominance of Proteobacteria (relative abundance (% of all sequences): 75% versus 51% in spring) and Fusobacteria (absolute abundance (% of children): 14% versus 2% in spring), and in spring a predominance of Bacteroidetes (relative abundance: 19% versus 3% in fall/winter, absolute abundance: 91% versus 54% in fall/winter), and Firmicutes. The latter increase is mainly due to (Brevi)bacillus and Lactobacillus species (absolute abundance: 96% versus 10% in fall/winter) which are like Bacteroidetes species generally related to healthy ecosystems. The observed seasonal effects could not be attributed to recent antibiotics or viral co-infection.The NP microbiota of young children is highly diverse and appears different between seasons. These differences seem independent of antibiotic use or viral co-infection.