Identification of New Microfoci and Genetic Characterization of Tick-Borne Encephalitis Virus Isolates from Eastern Germany and Western Poland

(1) Background: Tick-borne encephalitis (TBE) is the most important tick-borne viral disease in Eurasia, although effective vaccines are available. Caused by the tick-borne encephalitis virus (TBEV, syn. Orthoflavivirus encephalitidis), in Europe, it is transmitted by ticks like Ixodes ricinus and Dermacentor reticulatus. TBEV circulates in natural foci, making it endemic to specific regions, such as southern Germany and northeastern Poland. Our study aimed to identify new TBEV natural foci and genetically characterize strains in ticks in previously nonendemic areas in Eastern Germany and Western Poland. (2) Methods: Ticks were collected from vegetation in areas reported by TBE patients. After identification, ticks were tested for TBEV in pools of a maximum of 10 specimens using real-time RT-PCR. From the positive TBEV samples, E genes were sequenced. (3) Results: Among 8400 ticks from 19 sites, I. ricinus (n = 4784; 56.9%) was predominant, followed by D. reticulatus (n = 3506; 41.7%), Haemaphysalis concinna (n = 108; 1.3%), and I. frontalis (n = 2; <0.1%). TBEV was detected in 19 pools originating in six sites. The phylogenetic analyses revealed that TBEV strains from Germany and Poland clustered with other German strains, as well as those from Finland and Estonia. (4) Conclusions: Although there are still only a few cases are reported from these areas, people spending much time outdoors should consider TBE vaccination.

One Health in action: Investigation of the first detected local cluster of fatal borna disease virus 1 (BoDV-1) encephalitis, Germany 2022

BACKGROUND

Zoonotic Borna disease virus 1 (BoDV-1) causes fatal encephalitis in humans and animals. Subsequent to the detection of two paediatric cases in a Bavarian municipality in Germany within three years, we conducted an interdisciplinary One Health investigation. We aimed to explore seroprevalence in a local human population with a risk for BoDV-1 exposure as well as viral presence in environmental samples from local sites and BoDV-1 prevalence within the local small mammal population and its natural reservoir, the bicoloured white-toothed shrew (Crocidura leucodon).

METHODS

The municipality's adult residents participated in an anonymised sero-epidemiological study. Potential risk factors and clinical symptoms were assessed by an electronic questionnaire. Small mammals, environmental samples and ticks from the municipality were tested for BoDV-1-RNA. Shrew-derived BoDV-1-sequences together with sequences of the two human cases were phylogenetically analysed.

RESULTS

In total, 679 citizens participated (response: 41 %), of whom 38 % reported shrews in their living environment and 19 % direct shrew contact. No anti-BoDV-1 antibodies were detected in human samples. BoDV-1-RNA was also undetectable in 38 environmental samples and 336 ticks. Of 220 collected shrews, twelve of 40 C. leucodon (30%) tested BoDV-1-RNA-positive. BoDV-1-sequences from the previously diagnosed two paediatric patients belonged to two different subclades, that were also present in shrews from the municipality.

INTERPRETATION

Our data support the interpretation that human BoDV-1 infections are rare even in endemic areas and primarily manifest as severe encephalitis. Sequence analysis linked both previous paediatric human infections to the local shrew population, but indicated independent infection sources.

FUNDING

The project was partly financed by funds of the German Federal Ministry of Education and Research (grant numbers: 01KI2005A, 01KI2005C, 01KI1722A, 01KI1722C, 01KI2002 to MaBe, DR, RGU, DT, BS) as well as by the ReForM-A programme of the University Hospital Regensburg (to MaBa) and by funds of the Bavarian State Ministry of Health, Care and Prevention, project "Zoonotic Bornavirus Focal Point Bavaria - ZooBoFo" (to MaBa, MaBe, BS, MMB, DR, PS, RGU).

Tick-borne diseases in the North Sea region-A comprehensive overview and recommendations for diagnostics and treatment

As part of the NorthTick project, co-funded by the European Union through the European Regional Development Fund and the North Sea Region Programme, specialists in the field of tick-borne diseases from seven North Sea countries co-operated with patient organisations and governmental health care institutions to provide this comprehensive overview of diagnostics and treatment recommendations in the region for Lyme borreliosis, Borrelia miyamotoi infection, tick-borne encephalitis, human granulocytic anaplasmosis, rickettsiosis, neoehrlichiosis and babesiosis. The main conclusion is that the recommendations in these northern countries are essentially the same, with very few differences. This overview presents the current diagnostics and provides useful clinical guidance.

Prior flavivirus immunity skews the yellow fever vaccine response to cross-reactive antibodies with potential to enhance dengue virus infection

The yellow fever 17D vaccine (YF17D) is highly effective but is frequently administered to individuals with pre-existing cross-reactive immunity, potentially impacting their immune responses. Here, we investigate the impact of pre-existing flavivirus immunity induced by the tick-borne encephalitis virus (TBEV) vaccine on the response to YF17D vaccination in 250 individuals up to 28 days post-vaccination (pv) and 22 individuals sampled one-year pv. Our findings indicate that previous TBEV vaccination does not affect the early IgM-driven neutralizing response to YF17D. However, pre-vaccination sera enhance YF17D virus infection in vitro via antibody-dependent enhancement (ADE). Following YF17D vaccination, TBEV-pre-vaccinated individuals develop high amounts of cross-reactive IgG antibodies with poor neutralizing capacity. In contrast, TBEV-unvaccinated individuals elicit a non-cross-reacting neutralizing response. Using YF17D envelope protein mutants displaying different epitopes, we identify quaternary dimeric epitopes as the primary target of neutralizing antibodies. Additionally, TBEV-pre-vaccination skews the IgG response towards the pan-flavivirus fusion loop epitope (FLE), capable of mediating ADE of dengue and Zika virus infections in vitro. Together, we propose that YF17D vaccination conceals the FLE in individuals without prior flavivirus exposure but favors a cross-reactive IgG response in TBEV-pre-vaccinated recipients directed to the FLE with potential to enhance dengue virus infection.

Molting incidents of Hyalomma spp. carrying human pathogens in Germany under different weather conditions

BACKGROUND

Hyalomma marginatum and H. rufipes are two-host tick species, which are mainly distributed in southern Europe, Africa to central Asia but may also be found in Central and Northern Europe through introduction by migratory birds.

METHODS

Ticks were collected while feeding or crawling on animals and humans, or from the environment, in different regions in Germany, between 2019 and 2021 in a citizen science study and from 2022 to 2023 in the wake of this study.

RESULTS

From 2019 to 2023, a total of 212 Hyalomma adult ticks were detected in Germany. This included 132 H. marginatum and 43 H. rufipes ticks sent to research institutions and 37 photographic records that were only identified to genus level. The number of detected ticks varied over the years, with the highest number of 119 specimens recorded in 2019, followed by 57 in 2020. Most of the specimens were collected from horses, while some were collected from other animals, humans or found crawling on human clothes or other objects inside or outside houses. The screening of 175 specimens for Crimean-Congo hemorrhagic fever virus and of 132 specimens for Babesia/Theileria spp. by PCR gave negative results, while human-pathogenic Rickettsia were detected in 44% (77/175) of the total samples. Subsequent amplicon sequencing and phylogenetic analysis of representative samples determined the species of 41 Rickettsia aeschlimannii and one R. slovaca sequences.

CONCLUSIONS

Analysis of climatic factors indicated a significantly higher probability of Hyalomma occurrence at locations with higher average spring temperature during the years 2019 and 2020 compared to randomly generated pseudo-absence locations. Dry and hot conditions probably facilitated Hyalomma nymphs' survival and molting into adults during these years.

Exotic ticks removed from German travelers

We report the finding of five nymphs and three adult ticks attached to German tourists while traveling the American continents. All eight specimens were morphologically identified and confirmed genetically using the 16S rRNA gene and screened for Rickettsia spp. infections. Five tick species were identified: one Amblyomma mixtum nymph from Ecuador, one Amblyomma varium nymph from Colombia, three Amblyomma coelebs nymphs from Costa Rica, one Amblyomma americanum male from the USA, one Dermacentor andersoni female and one D. andersoni male from Canada. Tick-borne microorganisms screening using the pan-Rickettsia-PCR resulted in two positive and six negative ticks. The A. mixtum nymph was positive for Rickettsia amblyommatis, while the D. andersoni female was positive for Rickettsia peacockii.

Seroprevalence of tick-borne encephalitis virus in wild and domestic animals in northern Germany

Tick-borne encephalitis virus (TBEV) is a tick-transmitted flavivirus, which can infect humans and animals, sometimes even with a fatal outcome. Since many decades, TBEV is endemic in southern Germany, while only sporadic occurrence has been noted in northern parts of the country so far. Nevertheless, autochthonous human clinical cases are increasing in the federal state of Lower Saxony in north-western Germany, and several natural foci of TBEV transmission have recently been detected in this federal state. In order to shed more light on the current distribution of TBEV in Lower Saxony, the present study examined blood samples from wild and domestic animals for antibodies against TBEV. Overall, samples from 4,085 animals were tested by ELISA, including wild boar (N = 1,208), roe deer (N = 149), red deer (N = 61), fallow deer (N = 18), red foxes (N = 9), nutria (N = 9), raccoon dogs (N = 3), raccoons (N = 3), badgers (N = 1), European pine martens (N = 1), horses (N = 574), sheep (N = 266), goats (N = 67), dogs (N = 1,317) and cats (N = 399). Samples with an ELISA result of ≥60 Vienna units (VIEU)/ml were subjected to confirmatory serum neutralization tests (SNT). In total, 343 of 4,085 (8.4%) animals tested positive for anti-TBEV-IgG by ELISA, of which 60 samples were confirmed by SNT. Samples of 89 animals showed a cytotoxic effect in the SNT and were excluded from seroprevalence calculation, resulting in an overall seroprevalence of 1.5% (60/3,996). Seroprevalence was higher among wild animals (wild boar: 2.9% [34/1,190], roe deer: 2.7% [4/149], red deer: 1.7% [1/60], fallow deer: 5.6% [1/18]) than among domestic animals (dogs: 1.1% [15/1,317], horses: 0.8% [4/505], sheep: 0.4% [1/266]). No anti-TBEV-antibodies were detected in the other wild animal species as well as goats and cats. A notable clustering of positive samples was observed in districts where TBEV transmission foci have been described. Further clusters in other districts suggest the existence of so far undetected transmission foci, underlining the fact that both wild and domestic animals are useful sentinels for monitoring the spread of TBEV.

[Integrating Public Health Expertise in Research: a Series of Workshops about Vector-Borne and Other Zoonotic Diseases]

Research groups must understand the needs and requirements of the public health service to be able to develop tools and strategies for supporting it in risk assessment and risk communication. The zoonotic research consortia RoBoPub, Q-GAPS, TBENAGER and ZooBoCo used the format of workshops to include the expertise of the public health service system in their work. We present the results of three workshops that were held with representatives of the German public health service as part of the annual congress of the Federal Association of Physicians of German Public Health Departments in 2018, 2019 and 2022. Each workshop, held in a world-café format, lasted 90 minutes and had its own thematic focus. In the first workshop, information on the goals, problems, solutions and expectations of the public health service from the research consortia concerning exposure to rodent-borne infections during their occupational and leisure-time activities as well as the use of risk maps was collected. In the second and third workshops, participants developed risk communication strategies based on scenarios of outbreaks and identifications of new risk areas. Each workshop had more than 20 participants, of which at least half worked for local public health authorities. Foremost, participants expected practical, target group-specific material for risk communication from the research groups. According to the experience of most participants, direct contact with the affected groups was essential for risk communication. To raise awareness of the situation and establish contact with the relevant target groups, social media can complement traditional media, especially for hard-to-reach groups. However, their use should be considered and planned carefully. The workshop format was appropriate for integrating the public health expertise in the research activities. The expectations of the public health service on material for risk communication could be translated into a guideline, a risk management plan and pathogen descriptions by the research groups. When integrating the expertise of the public health authorities in their work, research groups should consider how to reach a suitable panel of representatives and how to keep the workload for those at an acceptably low level.

High neutralizing antibody mismatch as a possible reason for vaccine failure in two children with severe tick-borne encephalitis

We describe two adolescents (13 and 16 years old) with severe tick-borne encephalitis (TBE) and vaccination breakthrough (VBT). Both suffer from severe persistent neurologic sequelae. Both patients had high TBE-IgG-titers after vaccination at the beginning of the infection and a low or missing TBE-IgM response (Type 2 vaccine failure). Neutralization tests show low titers against the respective infecting TBE virus strain and higher titers against the vaccine strain at the beginning of the infection implying an individual weak or impaired immune response to the respective virus as possible cause of TBE vaccine failure. We do not know of any similar observation or explanation for the phenomenon and at the moment can only speculate of a severe course correlated to highly mismatched IgG. This constellation of high TBE IgGs, the lack of immune response and a severe course strongly resembles the severe TBE courses that occurred in the past after TBE immunoglobulin administration. To our knowledge differentiation between structural and functional antibodies by neutralization tests with a) the affecting TBE virus strain and b) the vaccine virus strain in TBE vaccine failures has never been described before. We conclude (1) to consider a TBE virus infection also in vaccinated children presenting with meningoencephalitis, (2) to perform a broad immunological work-up in severe TBE especially after VBT, (3) to further study if high mismatch IgG's are a possible reason for vaccine failure.

Impact of climate change on vector- and rodent-borne infectious diseases

Background

Endemic and imported vector- and rodent-borne infectious agents can be linked to high morbidity and mortality. Therefore, vector- and rodent-borne human diseases and the effects of climate change are important public health issues.

Methods

For this review, the relevant literature was identified and evaluated according to the thematic aspects and supplemented with an analysis of surveillance data for Germany.

Results

Factors such as increasing temperatures, changing precipitation patterns, and human behaviour may influence the epidemiology of vector- and rodent-borne infectious diseases in Germany.

Conclusions

The effects of climatic changes on the spread of vector- and rodent-borne infectious diseases need to be further studied in detail and considered in the context of climate adaptation measures.

[Viral zoonoses in Germany: a One Health perspective]

The COVID-19 pandemic and the increasing occurrence of monkeypox (mpox) diseases outside Africa have illustrated the vulnerability of populations to zoonotic pathogens. In addition, other viral zoonotic pathogens have gained importance in recent years.This review article addresses six notifiable viral zoonotic pathogens as examples to highlight the need for the One Health approach in order to understand the epidemiology of the diseases and to derive recommendations for action by the public health service. The importance of environmental factors, reservoirs, and vectors is emphasized, the diseases in livestock and wildlife are analyzed, and the occurrence and frequency of diseases in the population are described. The pathogens selected here differ in their reservoirs and the role of vectors for transmission, the impact of infections on farm animals, and the disease patterns observed in humans. In addition to zoonotic pathogens that have been known in Germany for a long time or were introduced recently, pathogens whose zoonotic potential has only lately been shown are also considered.For the pathogens discussed here, there are still large knowledge gaps regarding the transmission routes. Future One Health-based studies must contribute to the further elucidation of their transmission routes and the development of prevention measures. The holistic approach does not necessarily include a focus on viral pathogens/diseases, but also includes the question of the interaction of viral, bacterial, and other pathogens, including antibiotic resistance and host microbiomes.

Increased Vaccination Diversity Leads to Higher and Less-Variable Neutralization of TBE Viruses of the European Subtype

Tick-borne encephalitis (TBE) is an infectious disease of the central nervous system. The causative agent is the tick-borne encephalitis virus (TBEV), which is most commonly transmitted by tick bites, but which may also be transmitted through the consumption of raw dairy products or, in rare instances, via infected transfusions, transplants, or the slaughter of infected animals. The only effective preventive option is active immunization. Currently, two vaccines are available in Europe-Encepur^® and FSME-IMMUN^®. In Central, Eastern, and Northern Europe, isolated TBEV genotypes belong mainly to the European subtype (TBEV-EU). In this study, we investigated the ability of these two vaccines to induce neutralizing antibodies against a panel of diverse natural TBEV-EU isolates from TBE-endemic areas in southern Germany and in regions of neighboring countries. Sera of 33 donors vaccinated with either FSME-IMMUN^®, Encepur^®, or a mixture of both were tested against 16 TBEV-EU strains. Phylogenetic analysis of the TBEV-EU genomes revealed substantial genetic diversity and ancestry of the identified 13 genotypic clades. Although all sera were able to neutralize the TBEV-EU strains, there were significant differences among the various vaccination groups. The neutralization assays revealed that the vaccination using the two different vaccine brands significantly increased neutralization titers, decreased intra-serum variance, and reduced the inter-virus variation.

Tick-borne encephalitis virus IgG antibody surveillance: vaccination- and infection-induced seroprevalences, south-western Germany, 2021

BackgroundThe exact epidemiology of tick-borne encephalitis virus (TBEV) infections is unknown because many TBEV infections have an influenza-like or asymptomatic course. Surveillance data are based on patients with any (predominantly neurological) symptoms that prompted diagnostic testing. Infection- and vaccine-induced antibodies against TBEV can be distinguished using an NS1 IgG ELISA.AimIn a seroprevalence study we aimed to investigate TBEV antibody prevalence, incidences, manifestation indices and potential protection rates in a highly endemic district in south-western Germany.MethodsWe analysed 2,220 samples from healthy blood donors collected between May and September 2021. The reported number of TBEV infections was provided on a sub-district level by the local public health authorities. Blood samples were first screened using a TBEV IgG ELISA. In a second step, all positive samples were further analysed with a recently established NS1 IgG ELISA. The presence of specific antibodies against TBEV (excluding cross-reacting antibodies against other flaviviruses) was confirmed by testing screening-positive samples with a microneutralisation assay.ResultsOf 2,220 included samples, 1,257 (57%) tested positive by TBEV IgG ELISA and 125 tested positive for infection-induced TBEV NS1 antibodies, resulting in a TBEV NS1 IgG seroprevalence at 5.6% in our population. The yearly incidence based on the NS1 ELISA findings resulted in 283 cases per 100,000 inhabitants.ConclusionUsing the TBEV NS1 IgG assay, we confirmed a manifestation index of ca 2% and a high incidence of predominantly silent TBEV infections (> 250/100,000/year), which exceeds the incidence of notified cases (4.7/100,000/year) considerably.

Serological Protection Rates against TBEV Infection in Blood Donors from a Highly Endemic Region in Southern Germany

Background: Tick-borne encephalitis (TBE) is the most significant tick-borne disease in Europe and Asia, with more than 10,000 cases per year worldwide. A surge of reported TBE cases can be observed despite the availability of highly efficient vaccines. There is little known about the serological immune protection rate of the population in Germany. The seroprotection rate is defined as the presence of neutralizing antibodies. In contrast, the vaccination rate, as defined by public health agencies, may differ from the true protection rate in a population. Materials and Methods: 2220 blood samples from inhabitants of the county Ortenaukreis in the Federal State of Baden-Württemberg in Germany were included in the study. These were tested for anti-TBEV IgG antibodies by an anti-TBEV-IgG-ELISA. Subsequently, all TBEV-IgG positive samples were confirmed for neutralizing antibodies in the micro serum neutralization assay. Results: From the overall 2220 samples, 2104 were included in the comparison because of the selection of specific age groups (ages 20–69). In our sample size, we found an average serological protection rate (presence of neutralizing antibodies) of 57% (518/908) for the female blood donors and of 52% (632/1196) for the male blood donors. Discussion: In this study, we present new findings on a highly endemic region in southern Germany. Additionally, we present current data regarding the serological TBEV protection rates in the Ortenaukreis in southern Germany and compare these with a dataset published by the RKI, which is based on vaccination reports of the primary care providers and health care insurers, and with a self-reporting study conducted by a vaccine manufacturer. Our results significantly exceed the official numbers of average active vaccination status by 23.2% for females and by 21% for males. This might indicate an even longer persistence of TBE-vaccination-induced antibody titers than previously assumed.

Ticks and Rickettsiae Associated with Wild Animals Sold in Bush Meat Markets in Cameroon

Ticks are obligate blood-sucking parasites of wild animals and transmit many zoonotic microorganisms that can spread to domesticated animals and then to humans. In Cameroon, little is known about tick diversity among wildlife, especially for animals which are hunted for human consumption. Therefore, this survey was undertaken to investigate tick and Rickettsia species diversity parasitizing the wild animals sold in bush meat markets in Cameroon. In total, 686 ticks were collected and identified to the species level based on morphology, and some were genetically analyzed using the 16S rRNA gene. Eighteen tick species belonging to five genera were identified: Amblyomma spp. (Amblyomma compressum, Amblyomma flavomaculatum, and Amblyomma variegatum), Haemaphysalis spp. (Haemaphysalis camicasi, Haemaphysalis houyi, Haemaphysalis leachi, and Haemaphysalis parmata), Hyalomma spp. (Hyalomma nitidum, Hyalomma rufipes, and Hyalomma truncatum), Ixodes spp. (Ixodes rasus and Ixodes moreli), and Rhipicephalus spp. (Rhipicephalus guilhoni, Rhipicephalus moucheti, Rhipicephalus muhsamae, Rhipicephalus microplus, Rhipicephalus camicasi, and Rhipicephalus linnaei). In terms of Rickettsia important for public health, two Rickettsia spp., namely Rickettsia aeschlimannii and Rickettsia africae, were detected in Hyalomma spp. and Amblyomma spp., respectively. Distinct tick-pathogen patterns were present for divergent sequences of R. africae associated with exclusively A. variegatum vectors (type strain) versus vectors comprising A. compressum, A. flavomaculatum, and A. variegatum. This suggests possible effects of vector species population dynamics on pathogen population circulation dynamics. Furthermore, Candidatus Rickettsia africaustralis was detected for the first time in Cameroon in I. rasus. This study highlights the high diversity of ticks among wildlife sold in bush meat markets in Cameroon.

Seroprevalence of Tick-Borne Encephalitis (TBE) Virus Antibodies in Wild Rodents from Two Natural TBE Foci in Bavaria, Germany

Tick-borne encephalitis (TBE) is Eurasia's most important tick-borne viral disease. Rodents play an important role as natural hosts. Longitudinal studies on the dynamics of the seroprevalence rates in wild rodents in natural foci over the year are rare, and the dynamics of the transmission cycle still need to be understood. To better understand the infection dynamics, rodents were captured in a capture-mark-release-recapture-study in two natural foci in Bavaria, Germany, monthly from March 2019 to October 2022. Overall, 651 blood and thoracic lavage samples from 478 different wild rodents (Clethrionomys glareolus and Apodemus flavicollis) were analyzed for antibodies against tick-borne encephalitis virus (TBEV) by indirect immunofluorescence assay (IIFA) and confirmed using a serum neutralization test (SNT). Furthermore, a generalized linear mixed model (GLMM) analysis was performed to investigate ecological and individual factors for the probability of infection in rodents. Clethrionomys glareolus (19.4%) had a higher seroprevalence than A. flavicollis (10.5%). Within Cl. glareolus, more males (40.4%) than females (15.6%) were affected, and more adults (25.4%) than juveniles (9.8%). The probability of infection of rodents rather depends on factors such as species, sex, and age than on the study site of a natural focus, year, and season. The high incidence rates of rodents, particularly male adult bank voles, highlight their critical role in the transmission cycle of TBEV in a natural focus and demonstrate that serologically positive rodents can be reliably detected in a natural focus regardless of season or year. In addition, these data contribute to a better understanding of the TBEV cycle and thus could improve preventive strategies for human infections.

Rickettsia spp. in Ticks of South Luangwa Valley, Eastern Province, Zambia

Ticks are important vectors for Rickettsia spp. belonging to the Spotted Fever Group responsible for causing Rickettsiosis worldwide. Rickettsioses pose an underestimated health risk to tourists and local inhabitants. There is evidence of the presence of Rickettsia spp. in Zambia, however there is limited data. A total of 1465 ticks were collected in 20 different locations from dogs and cattle including one cat. Ticks were identified by morphological features or by sequencing of the 16S mitochondrial rRNA gene. Individual ticks were further tested for rickettsiae using a pan-Rickettsia real-time-PCR. Rickettsia species in PCR-positive ticks were identified by sequencing the 23S-5S intergenic spacer region or partial ompA gene, respectively. Seven tick species belonging to three different tick genera were found, namely: Amblyomma variegatum, Rhipicephalus appendiculatus, Rhipicephalus (Boophilus) microplus, Rhipicephalus simus, Rhipicephalus sanguineus, Rhipicephalus zambesiensis and Haemaphysalis elliptica. Out of the 1465 ticks collected, 67 (4.6%) tested positive in the pan-Rickettsia PCR. This study provides detailed data about the presence of Rickettsia species in South Luangwa Valley, Eastern Province, Zambia for the first time. High prevalence of Rickettsia africae in Amblyomma variegatum was found, which indicates the potential risk of infection in the investigated area. Furthermore, to our best knowledge, this is the first time Rickettsia massiliae, a human pathogen causing spotted fever, has been detected in Zambia.

Chikungunya virus (CHIKV) seroprevalence in the South Pacific populations of the Cook Islands and Vanuatu with associated environmental and social factors

BACKGROUND

Arthropod-borne diseases pose a significant and increasing risk to global health. Given its rapid dissemination, causing large-scale outbreaks with severe human infections and economic loss, the Chikungunya virus (CHIKV) is one of the most important arboviruses worldwide. Despite its significance, the real global impact of CHIKV remains underestimated as outbreak data are often incomplete and based solely on syndromic surveillance. During 2011-2016, the South Pacific Region was severely affected by several CHIKV-epidemics, yet the area is still underrepresented in arboviral research.

METHODS

465 outpatient serum samples collected between 08/2016 and 04/2017 on three islands of the island states Vanuatu (Espiritu Santo) and the Cook Islands (Rarotonga, Aitutaki) were tested for anti-CHIKV specific antibodies using Enzyme-linked immunosorbent Assays.

RESULTS

A total of 30% (Cook Islands) and 8% (Vanuatu) of specimens were found positive for anti-CHIKV specific antibodies with major variations in national and intranational immunity levels. Seroprevalence throughout all age groups was relatively constant. Four potential outbreak-protective factors were identified by comparing the different study settings: presence of Ae. albopictus (in absence of ECSA E1-A226V-mutation CHIKV), as well as low levels of human population densities, residents' travel activity and tourism.

CONCLUSION

This is the first seroprevalence study focussing on an arboviral disease in the Cook Islands and Vanuatu. It highlights the impact of the 2014/2015 CHIKV epidemic on the Cook Islands population and shows that a notable part of the Vanuatu test population was exposed to CHIKV although no outbreaks were reported. Our findings supplement the knowledge concerning CHIKV epidemics in the South Pacific Region and contribute to a better understanding of virus dissemination, including outbreak modifying factors. This study may support preventive and rapid response measures in affected areas, travel-related risk assessment and infection identification in returning travellers.

TRIAL REGISTRATION

ClinicalTrials.gov Aachen: 051/16_09/05/2016 Cook Islands Ref.: #16-16 Vanuatu Ref.: MOH/DG 10/1/1-GKT/lr.

Vector-borne and other pathogens of potential relevance disseminated by relocated cats

Large populations of unowned cats constitute an animal welfare, ecological, societal and public health issue worldwide. Their relocation and homing are currently carried out in many parts of the world with the intention of relieving suffering and social problems, while contributing to ethical and humane population control in these cat populations. An understanding of an individual cat’s lifestyle and disease status by veterinary team professionals and those working with cat charities can help to prevent severe cat stress and the spread of feline pathogens, especially vector-borne pathogens, which can be overlooked in cats. In this article, we discuss the issue of relocation and homing of unowned cats from a global perspective. We also review zoonotic and non-zoonotic infectious agents of cats and give a list of practical recommendations for veterinary team professionals dealing with homing cats. Finally, we present a consensus statement consolidated at the 15th Symposium of the Companion Vector-Borne Diseases (CVBD) World Forum in 2020, ultimately to help veterinary team professionals understand the problem and the role they have in helping to prevent and manage vector-borne and other pathogens in relocated cats.

Graphical Abstract

Update and prognosis of Dermacentor distribution in Germany: Nationwide occurrence of Dermacentor reticulatus

A considerable range expansion of Dermacentor reticulatus has been observed in several European countries, which is concerning in the light of its vector function for several pathogens, including Babesia canis and tick-borne encephalitis virus (TBEV). The present study provides an update on the distribution of Dermacentor ticks in Germany, using a citizen science approach. Ticks were collected by citizens from March 2020 to May 2021, and submitted along with information on the date and location of collection, potential hosts and details about the circumstances of discovery. In total, 3,292 Dermacentor specimens were received, of which 76.4% (2,515/3,292) were identified as D. reticulatus and 23.0% (758/3,292) as D. marginatus, while 0.6% (19/3,292) were too damaged for species-level identification. Dermacentor reticulatus was received from all federal states of Germany. Maxent species distribution models predicted suitable environmental conditions for D. reticulatus throughout Germany. Findings on the vegetation or on pastured animals without travel history confirmed the occurrence of this tick species as far north as the most northern German federal state Schleswig-Holstein. In contrast, the distribution of D. marginatus still appears to be limited to southwestern Germany, although the northward shift of the distribution limit observed in the preceding citizen science study, as compared with previous published distributions, was confirmed. This shift was also predicted by Maxent species distribution models, reflecting the broader distribution of the tick occurrence data contributed by citizens. Most D. reticulatus ticks were found on dogs (1,311/1,960, 66.9%), while D. marginatus was mainly discovered on hoofed animals (197/621, 31.7%) and humans (182/621, 29.3%). Human tick bites were reported in 0.7% (14/1,960) of host-assigned D. reticulatus and 3.4% (21/621) of host-assigned D. marginatus. Further studies to investigate an increasing endemisation of Babesia canis in Germany as well as the relevance of D. reticulatus for TBEV spread throughout the country, e.g., by traveling dogs, are urgently needed. In view of the activity of D. reticulatus during winter or the colder months, which complements that of Ixodes ricinus, a year-round tick protection of at least dogs is strongly recommended.

Frühsommer-Meningoenzephalitis (FSME)

Zusammenfassung. Die Frühsommer-Meningoenzephalitis (FSME) ist in weiten Teilen aller deutschsprachigen Länder endemisch verbreitet. In den meisten Regionen besteht ein Trend zur Zunahme der Inzidenz und zur Ausbreitung der befallenen Gebiete. Angesichts der Tatsache, dass bei einem Teil der Patienten die Diagnose nicht gestellt wird und dass der klinische Verlauf mit zunehmendem Alter schwerer ist, muss man vor allem bei Kindern und Adoleszenten von einem erheblichen Underreporting ausgehen. Infizierte Zecken übertragen das FSME-Virus, ein Flavivirus, bereits in den ersten Minuten nach dem Stich. Nach einer Inkubationszeit von 4 bis 28 Tagen treten in der ersten virämischen Phase uncharakteristische grippeartige Symptome auf. Nach einem symptomfreien Intervall kommt es bei einer Minderheit der befallenen Patienten zu unterschiedlichen neurologischen Syndromen, welche durch den Befall des Zentralnervensystems bedingt sind. Bleibende Organschäden sind häufig und bei etwa 1% der Fälle ist der Verlauf letal. Um die FSME zu diagnostizieren ist es essenziell, an diese Infektion zu denken und die Anamnese einer möglichen Exposition zu erheben. Je nach Phase der Krankheit wird man IgM- und/oder IgG-Antikörper feststellen können, dies aus dem Serum und/oder dem Liquor. Seltener und nur in der Anfangsphase der Krankheit lassen sich allenfalls Viren mittels PCR finden.

Decoding the Geography of Natural TBEV Microfoci in Germany: A Geostatistical Approach Based on Land-Use Patterns and Climatological Conditions

Background: Tickborne-encephalitis (TBE) is a potentially life-threating neurological disease that is mainly transmitted by ticks. The goal of the present study is to analyze the potential uniform environmental patterns of the identified TBEV microfoci in Germany. The results are used to calculate probabilities for the present distribution of TBEV microfoci in Germany based on a geostatistical model. Methods: We aim to consider the specification of environmental characteristics of locations of TBEV microfoci detected in Germany using open access epidemiological, geographical and climatological data sources. We use a two-step geostatistical approach, where in a first step, the characteristics of a broad set of environmental variables between the 56 TBEV microfoci and a control or comparator set of 3575 sampling points covering Germany are compared using Fisher's Exact Test. In the second step, we select the most important variables, which are then used in a MaxEnt distribution model to calculate a high resolution (400 × 400 m) probability map for the presence of TBEV covering the entire area of Germany. Results: The findings from the MaxEnt prediction model indicate that multi annual actual evapotranspiration (27.0%) and multi annual hot days (22.5%) have the highest contribution to our model. These two variables are followed by four additional variables with a lower, but still important, explanatory influence: Land cover classes (19.6%), multi annual minimum air temperature (14.9%), multi annual sunshine duration (9.0%), and distance to coniferous and mixed forest border (7.0%). Conclusions: Our findings are based on defined TBEV microfoci with known histories of infection and the repeated confirmation of the virus in the last years, resulting in an in-depth high-resolution model/map of TBEV microfoci in Germany. Multi annual actual evapotranspiration (27%) and multi annual hot days (22.5%) have the most explanatory power in our model. The results may be used to tailor specific regional preventive measures and investigations.

Molecular detection of tick-borne pathogens in Rhipicephalus sanguineus sensu stricto collected from dogs in the steppe and high plateau regions of Algeria

Epidemiology and distributions of canine tick-borne diseases as well as their veterinary and zoonotic significance are poorly understood in Algeria. The present study describes a molecular investigation of important tick-borne pathogens in Rhipicephalus sanguineus sensu stricto collected from domestic dogs in steppe and high plateau areas of central and eastern Algeria. In total, 1,043 ticks were collected from 147 domestic dogs, including 756 ticks from 124 dogs in the steppe region of Djelfa, and 287 ticks from 23 dogs in the high plateau area of Bordj Bou Arreridj. Ticks were divided into 384 pools (309 pools from Djelfa and 75 pools from Bordj Bou Arreridj) and tested for genomic materials of Crimean-Congo hemorrhagic fever virus (CCHFV) as well as DNA for Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis, Rickettsia spp., Babesia spp., and Hepatozoon spp. using PCR, sequencing and phylogenetic analysis. Hepatozoon spp. was most prevalent, with 160 positive pools (41.70%), and 12 of these were sequenced and identified as Hepatozoon canis. Babesia spp. was detected in 50 samples (13.0%), of which 11 were sequenced and identified as Babesia vogeli. A. platys and E. canis were detected in 92 (24.0%) and 15 (3.9%) of tested samples, respectively. Rickettsia spp. were detected in 24 (6.3%) samples, including 11 samples identified as R. massiliae, 6 samples identified as R. conorii conorii, and 7 samples could not be identified to species level. All 384 pools tested negative for CCHFV and A. phagocytophilum. In addition to detection of R. conorii conorii, R. massiliae, and E. canis, the present study provides the first molecular data for occurrence of A. platys, B. vogeli, and H. canis in Rh. sanguineus s.s. infesting dogs in Algeria. Further large scale studies should be conducted to better understand the epidemiology, distributions and importance of canine tick-borne pathogens in Algeria.

Recommendations to Improve Tick-Borne Encephalitis Surveillance and Vaccine Uptake in Europe

There has been an increase in reported TBE cases in Europe since 2015, reaching a peak in some countries in 2020, highlighting the need for better management of TBE risk in Europe. TBE surveillance is currently limited, in part, due to varying diagnostic guidelines, access to testing, and awareness of TBE. Consequently, TBE prevalence is underestimated and vaccination recommendations inadequate. TBE vaccine uptake is unsatisfactory in many TBE-endemic European countries. This review summarizes the findings of a scientific workshop of experts to improve TBE surveillance and vaccine uptake in Europe. Strategies to improve TBE surveillance and vaccine uptake should focus on: aligning diagnostic criteria and testing across Europe; expanding current vaccine recommendations and reducing their complexity; and increasing public education of the potential risks posed by TBEV infection.

Geo-Spatial Characteristics of 567 Places of Tick-Borne Encephalitis Infection in Southern Germany, 2018-2020

Tick-borne encephalitis (TBE) is a growing public health problem with increasing incidence and expanding risk areas. Improved prevention requires better understanding of the spatial distribution and ecological determinants of TBE transmission. However, a TBE risk map at sub-district level is still missing for Germany. We investigated the distribution and geo-spatial characteristics of 567 self-reported places of probable TBE infection (POI) from 359 cases notified in 2018-2020 in the study area of Bavaria and Baden-Wuerttemberg, compared to 41 confirmed TBE foci and 1701 random comparator places. We built an ecological niche model to interpolate TBE risk to the entire study area. POI were distributed heterogeneously at sub-district level, as predicted probabilities varied markedly across regions (range 0-93%). POI were spatially associated with abiotic, biotic, and anthropogenic geo-spatial characteristics, including summer precipitation, population density, and annual frost days. The model performed with 69% sensitivity and 63% specificity at an optimised probability threshold (0.28) and an area under the curve of 0.73. We observed high predictive probabilities in small-scale areas, consistent with the known circulation of the TBE virus in spatially restricted microfoci. Supported by further field work, our findings may help identify new TBE foci. Our fine-grained risk map could supplement targeted prevention in risk areas.

Contemporary diagnostics for medically relevant fastidious microorganisms belonging to the genera Anaplasma, Bartonella, Coxiella, Orientia, and Rickettsia

Many of the human infectious pathogens—especially the zoonotic or vector-borne bacteria—are fastidious organisms that are difficult to cultivate because of their strong adaption to the infected host culminating in their near-complete physiological dependence on this environment. These bacterial species exhibit reduced multiplication rates once they are removed from their optimal ecological niche. This fact complicates the laboratory diagnosis of the disease and hinders the detection and further characterization of the underlying organisms, e.g. at the level of their resistance to antibiotics due to their slow growth. Here, we describe the current state of microbiological diagnostics for five genera of human pathogens with a fastidious laboratory lifestyle. For Anaplasma spp., Bartonella spp., Coxiella burnetii, Orientia spp. and Rickettsia spp., we will summarize the existing diagnostic protocols, the specific limitations for implementation of novel diagnostic approaches and the need for further optimization or expansion of the diagnostic armamentarium. We will reflect upon the diagnostic opportunities provided by new technologies including mass spectrometry and next-generation nucleic acid sequencing. Finally, we will review the (im)possibilities of rapidly developing new in vitro diagnostic tools for diseases of which the causative agents are fastidiously growing and therefore hard to detect.

The interplay of viral loads, clinical presentation, and serological responses in SARS-CoV-2 – Results from a prospective cohort of outpatient COVID-19 cases

Risk factors for disease progression and severity of SARS-CoV-2 infections require an understanding of acute and long-term virological and immunological dynamics. Fifty-one RT-PCR positive COVID-19 outpatients were recruited between May and December 2020 in Munich, Germany, and followed up at multiple defined timepoints for up to one year. RT-PCR and viral culture were performed and seroresponses measured. Participants were classified applying the WHO clinical progression scale. Short symptom to test time (median 5.0 days; p = 0.0016) and high viral loads (VL; median maximum VL: 3∙10⁸ copies/mL; p = 0.0015) were indicative for viral culture positivity. Participants with WHO grade 3 at baseline had significantly higher VLs compared to those with WHO 1 and 2 (p = 0.01). VLs dropped fast within 1 week of symptom onset. Maximum VLs were positively correlated with the magnitude of Ro-N-Ig seroresponse (p = 0.022). Our results describe the dynamics of VLs and antibodies to SARS-CoV-2 in mild to moderate cases that can support public health measures during the ongoing global pandemic.

Effectiveness of TBE vaccination in southern Germany and Latvia

BACKGROUND

Tick-borne encephalitis (TBE) is a vaccine-preventable disease which may cause long-term sequelae and even death. The data on the long-term effectiveness of TBE vaccines are limited. Additionally, the vaccination schedule is complex which in part contributes towards sub-optimal uptake in TBE-endemic areas. The current ecological study measures vaccine effectiveness (VE) in two European countries.

METHODS

TBE VE was measured from 2007 to 2018 in Latvia and Southern German states by age group, vaccination history, and schedule compliance. TBE cases and vaccination history were obtained from the public health agencies for Latvia and the southern German federal states of Bavaria and Baden-Wuerttemberg. Cases were "within schedule" if a TBE infection was diagnosed within the time interval preceding the next scheduled dose and "outside schedule" if the diagnosis occurred after the next scheduled dose. Vaccine uptake was estimated via representative nationwide surveys.

RESULTS

VE after 2, 3, and ≥4 doses was high in both countries at 97.2%, 95.0%, and 95.4% for southern Germany, and 98.1%, 99.4%, and 98.8% for Latvia while within- schedule, and only showed marginal differences outside schedule at 90.6%, 89.9%, and 95.6% for southern Germany, and 97.4%, 98.4%, and 99.0% for Latvia regardless of age groups.

CONCLUSIONS

In both countries, VE after two and three primary doses within-schedule was very high in all age groups. Once receiving booster doses, high VE continued to be observed even in persons with extended intervals since the last dose received, suggesting that longer and more flexible booster intervals may be considered for sustainable long-term protection.

TBE Vaccination Breakthrough Cases-Does Age Matter?

Tick-borne encephalitis (TBE) vaccines are highly effective in preventing TBE and vaccine failures (VF) are rare events. In this study, we compared the age distribution of TBE cases and TBE VF in three endemic countries: Sweden, Southern Germany, and Latvia. While the age distribution of TBE cases was similar for those <50 years versus those ≥50 years in all three countries, in Sweden, a higher proportion of VF cases was ≥50 years, whereas most VF cases in Latvia were <50 years of age and more evenly distributed between those <50 years versus those ≥50 in Southern Germany. Here, theoretical explanations were provided, including differences in diagnostic practices, vaccine uptake between age groups, behavioral patterns and underlying medical conditions, as to why VF were generally older in Sweden than the other countries. There is no scientific rationale to give an extra priming dose of TBE vaccine to subjects ≥50 years of age.

Emerging SARS-CoV-2 variant B.1.1.7 reduces neutralisation activity of antibodies against wild-type SARS-CoV-2

Spike-specific antibodies contribute significantly to the neutralising activity against SARS-CoV-2 and are important for the therapeutic effect of convalescent plasma. B.1.1.7 is a recently emerged variant of SARS-CoV-2 that has several mutations in the gene encoding for the spike-protein. To assess the potential effect these mutations could have on the neutralising efficacy of antibodies, we evaluated 96 serum samples from convalescent plasma donors collected before the first occurrence of B.1.1.7 and tested their neutralising effect on wild-type SARS-CoV-2 and B.1.1.7. We found that B.1.1.7 is more resistant to neutralisation by convalescent plasma from patients infected with wild-type SARS-CoV-2 with an overall decrease in neutralising activity of 47.7%. Thus, the neutralising effect of convalescent plasma should be determined against the major circulating virus clades whenever possible to ensure the best possible therapeutic effect.

Long-term presence of tick-borne encephalitis virus in experimentally infected bank voles (Myodes glareolus)

Tick-borne encephalitis virus (TBEV) is a vector-borne pathogen that can cause serious neurological symptoms in humans. Across large parts of Eurasia TBEV is found in three traditional subtypes: the European, the Siberian and the Far-eastern subtype. Small mammalian animals play an important role in the transmission cycle as they enable the spread of TBEV among the vector tick population. To assess the impact of TBEV infection on its natural hosts, outbred bank voles (Myodes glareolus) were inoculated with one out of four European TBEV strains. Three of these TBEV strains were recently isolated in Germany. The forth one was the TBEV reference strain Neudörfl. Sampling points at 7, 14, 28, and 56 days post inoculation allowed the characterization of the course of infection. At each time point, six animals per strain were euthanized and eleven organ samples (brain, spine, lung, heart, small and large intestine, liver, spleen, kidney, bladder, sexual organ) as well as whole blood and serum samples were collected. The majority of bank voles (92/96) remained clinically unaffected after the inoculation with TBEV, but still developed a systemic infection during the first week, which transitioned to a viraemia and an infestation of the brain in some animals for the remainder of the first month. Viral RNA was found in whole blood samples of several animals (50/96), but only in a small fraction of the corresponding serum samples (4/50). From the whole blood, virus was successfully reisolated in cell culture until 14 days after inoculation. Less than five percent of all inoculated bank voles (4/96) displayed signs of distress in combination with a rapid weight loss and had to be euthanized prematurely. Overall, the recently isolated TBEV strains showed marked differences, such as a more frequent development of long-term viraemia and a higher detection rate of viral RNA in various organs, in comparison to the reference strain Neudörfl. Overall, our data suggest that the bank vole is a potential amplifying host in the TBEV transmission cycle and appears to be highly adapted to circulating TBEV strains.

Tick species from cattle in the Adama Region of Ethiopia and pathogens detected

Ticks will diminish productivity among farm animals and transmit zoonotic diseases. We conducted a study to identify tick species infesting slaughter bulls from Adama City and to screen them for tick-borne pathogens. In 2016, 291 ticks were collected from 37 bulls in Adama, which were ready for slaughter. Ticks were identified morphologically. Total genomic DNA was extracted from ticks and used to test for Rickettsia spp. with real-time PCR. Species identification was done by phylogenetic analysis using sequencing that targeted the 23S-5S intergenic spacer region and ompA genes. Four tick species from two genera, Amblyomma and Rhipicephalus, were identified. Amblyomma cohaerens was the dominant species (n = 241, 82.8%), followed by Amblyomma variegatum (n = 22, 7.5%), Rhipicephalus pulchellus (n = 19, 6.5%), and Rhipicephalus decoloratus (n = 9, 3.0%). Among all ticks, 32 (11%) were positive for Rickettsia spp. and 15 (5.2%) of these were identified as R. africae comprising at least two genetic clades, occurring in A. variegatum (n = 10) and A. cohaerens (n = 5). The remainder of Rickettsia-positive samples could not be amplified due to low DNA yield. Furthermore, another 15 (5.2%) samples carried other pathogenic bacteria: Ehrlichia ruminantium (n = 9; 3.1%) in A. cohaerens, Ehrlichia sp. (n = 3; 1%) in Rh. pulchellus and A. cohaerens, Anaplasma sp. (n = 1; 0.5%) in A. cohaerens, and Neoehrlichia mikurensis (n = 2; 0.7%) in A. cohaerens. All ticks were negative for Bartonella spp., Babesia spp., Theileria spp., and Hepatozoon spp. We reported for the first time E. ruminatium, N. mikurensis, Ehrlichia sp., and Anaplasma sp. in A. cohaerens. Medically and veterinarily important pathogens were mostly detected from A. variegatum and A. cohaerens. These data are relevant for a One-health approach for monitoring and prevention of tick-borne disease transmission.

Occurrence of Anti-Rickettsia spp. Antibodies in Hospitalized Patients with Undifferentiated Febrile Illness in the Southern Region of Kazakhstan

Undifferentiated febrile illness still represents a demanding medical problem all over the world, but primarily in low- and middle-income countries. Scientific and clinical investigations related to undifferentiated febrile illness and rickettsial diseases in Kazakhstan are lacking. This study reflects the investigation of antibodies against spotted fever group (SFG) and typhus group (TG) rickettsiae in patients with undifferentiated febrile illness in the southern region of Kazakhstan (Almaty and Kyzylorda oblasts). Paired serum samples were gathered from 13 hospitals in these two oblasts and explored for the presence of IgM and IgG antibodies against typhus group and IgG antibodies against spotted fever group rickettsiae using ELISA. Patient's questionnaires were statistically analyzed. In total, 802 inpatients from Almaty (N = 9) and Kyzylorda (N = 4) hospitals were included in this research. Based on ELISA results, 250 patients out of 802 (31.2%) from both oblasts had IgG antibodies against SFG rickettsiae. Results from 11 (1.4%) patients indicated acute infection with tick-borne rickettsiosis. Regarding TG rickettsiae (R. typhi), a past infection was detected in 248 (30.9%) febrile patients and acute infection in 22 (2.7%) patients in the two selected oblasts. The data indicated that SFG and TG rickettsioses are present in Kazakhstan. Kazakh physicians should be aware of these emerging diseases in both investigated oblasts because the occurrence of these diseases is not suspected during day-to-day clinical practice. The identification of rickettsial pathogens and implementation of modern laboratory methods for the diagnostics of rickettsioses are in need throughout Kazakhstan.

Tick-Borne Encephalitis Vaccination Protects from Alimentary TBE Infection: Results from an Alimentary Outbreak

In May 2017, a hospitalized index case of tick-borne encephalitis (TBE) was confirmed by Serology. The case was linked to alimentary infection by raw milk from a goat farm in the region of Tübingen, Baden-Württemberg, Germany, where no previous TBE cases in the area had been reported before. The TBE focus was confirmed by isolation of the TBE virus from ticks and Serological confirmation of past infection in one of the five flock goats. Additional investigations by the local public health office identified 27 consumers of goat milk at the putative period of exposure. For 20/27 exposed persons, anamnestic information was gained by the local public health office. Twelve/fourteen exposed and non-vaccinated people developed clinical illness and were confirmed as TBE cases by Serology. Five/six vaccinated and exposed people did not develop the disease. The one exposed and vaccinated person had their last TBE vaccination booster more than 15 years ago, and therefore a booster was more than 10 years overdue. None of the regularly vaccinated and exposed persons developed clinical overt TBE infection. We report the first known TBE outbreak, during which, protection by TBE vaccination against alimentary TBE infection was demonstrated.

SARS-CoV-2 Seroprevalence among Health Care Workers-A Voluntary Screening Study in a Regional Medical Center in Southern Germany

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is associated with a potentially severe clinical manifestation, coronavirus disease 2019 (COVID-19), and currently poses a worldwide challenge. Health care workers (HCWs) are at the forefront of any health care system and thus especially at risk for SARS-CoV-2 infection due to their potentially frequent and close contact with patients suffering from COVID-19. Serum samples from 198 HCWs with direct patient contact of a regional medical center and several outpatient facilities were collected during the early phase of the pandemic (April 2020) and tested for SARS-CoV-2-specific antibodies. Commercially available IgA- and IgG-specific ELISAs were used as screening technique, followed by an in-house neutralization assay for confirmation. Neutralizing SARS-CoV-2-specific antibodies were detected in seven of 198 (3.5%) tested HCWs. There was no significant difference in seroprevalence between the regional medical center (3.4%) and the outpatient institution (5%). The overall seroprevalence of neutralizing SARS-CoV-2-specific antibodies in HCWs in both a large regional medical center and a small outpatient institution was low (3.5%) at the beginning of April 2020. The findings may indicate that the timely implemented preventive measures (strict hygiene protocols, personal protective equipment) were effective to protect from transmission of an airborne virus when only limited information on the pathogen was available.

The Stable Matching Problem in TBEV Enzootic Circulation: How Important Is the Perfect Tick-Virus Match?

Tick-borne encephalitis virus (TBEV), like other arthropod-transmitted viruses, depends on specific vectors to complete its enzootic cycle. It has been long known that Ixodes ricinus ticks constitute the main vector for TBEV in Europe. In contrast to the wide distribution of the TBEV vector, the occurrence of TBEV transmission is focal and often restricted to a small parcel of land, whereas surrounding areas with seemingly similar habitat parameters are free of TBEV. Thus, the question arises which factors shape this focal distribution of TBEV in the natural habitat. To shed light on factors driving TBEV-focus formation, we used tick populations from two TBEV-foci in Lower Saxony and two TBEV-foci from Bavaria with their respective virus isolates as a showcase to analyze the impact of specific virus isolate-tick population relationships. Using artificial blood feeding and field-collected nymphal ticks as experimental means, our investigation showed that the probability of getting infected with the synonymous TBEV isolate as compared to the nonsynonymous TBEV isolate was elevated but significantly higher only in one of the four TBEV foci. More obviously, median viral RNA copy numbers were significantly higher in the synonymous virus–tick population pairings. These findings may present a hint for a coevolutionary adaptation of virus and tick populations.

Small Mammals as Reservoir for Zoonotic Agents in Afghanistan

INTRODUCTION

Rodents and other small mammals can serve as reservoirs for a large number of zoonotic pathogens. A higher risk of infection with rodent-borne pathogens exists for humans with direct contact to rodents and/or their excretions, e.g., soldiers in operation areas. To date, little is known about endemic human pathogenic disease agents that are naturally associated with small mammals in Afghanistan. The aim of this study was to screen abundant rodents and insectivores collected from 2009 to 2012 in four field camps of the German Federal Armed Forces (Bundeswehr) in Northern Afghanistan for the presence of different pathogens.

MATERIALS AND METHODS

Isolated nucleic acids from ear pinna were screened by real-time PCR for spotted fever group (SFG) rickettsiae and from liver samples for Francisella spp., Coxiella burnetii, Brucella spp., Yersinia pestis, and poxvirus. Chest cavity lavage (CCL) samples were tested for antibodies against SFG and typhus group (TG) rickettsiae, as well as against flaviviruses using an indirect immunofluorescence assay.

RESULTS

Rickettsial DNA was detected in 7/750 (1%) ear pinna samples with one being identified as Rickettsia conorii. Antibodies against SFG rickettsiae were detected in 15.3% (n = 67/439) of the small mammals; positive samples were only from house mice (Mus musculus). Antibodies against TG rickettsiae were found in 8.2% (n = 36/439) of the samples, with 35 from house mice and one from gray dwarf hamster (Cricetulus migratorius). Flavivirus-reactive antibodies were detected in 2.3% (n = 10/439) of the investigated CCL samples; again positive samples were exclusively identified in house mice. All 199 investigated liver-derived DNA preparations were negative in the Francisella spp., C. burnetii, Brucella spp., Y. pestis, and poxvirus-specific PCRs.

CONCLUSIONS

Further investigations will have to prove the potential value of rodents in army camps as sentinel animals.

The complex interplay of climate, TBEV vector dynamics and TBEV infection rates in ticks-Monitoring a natural TBEV focus in Germany, 2009-2018

BACKGROUND

Tick-borne encephalitis (TBE) is the most important tick-borne viral disease in Eurasia and causes disease in humans and in a number of animals, among them dogs and horses. There is still no good correlation between tick numbers, weather conditions and human cases. There is the hypothesis that co-feeding due to simultaneous occurrence of larvae and nymphs may be a factor for the increased transmission of the virus in nature and for human disease. Based on long-term data from a natural TBEV focus, phylogenetic results and meteorological data we sought to challenge this hypothesis.

METHODS

Ticks from an identified TBE natural focus were sampled monthly from 04/2009 to 12/2018. Ticks were identified and pooled. Pools were tested by RT-qPCR. Positive pools were confirmed by virus isolation and/or sequencing of additional genes (E gene, NS2 gene). Temperature data such as the decadal (10-day) mean daily maximum air temperature (DMDMAT) were obtained from a nearby weather station and statistical correlations between tick occurrence and minimal infection rates (MIR) were calculated.

RESULTS

In the study period from 04/2009 to 12/2018 a total of 15,530 ticks (2,226 females, 2,268 males, 11,036 nymphs) were collected. The overall MIR in nymphs over the whole period was 77/15,530 (0.49%), ranging from 0.09% (2009) to 1.36% (2015). The overall MIR of female ticks was 0.76% (17/2,226 ticks), range 0.14% (2013) to 3.59% (2016). The overall MIR of males was 0.57% (13/2,268 ticks), range from 0.26% (2009) to 0.97% (2015). The number of nymphs was statistically associated with a later start of spring/vegetation period, indicated by the onset of forsythia flowering.

CONCLUSION

There was no particular correlation between DMDMAT dynamics in spring and/or autumn and the MIR of nymphs or adult ticks detected. However, there was a positive correlation between the number of nymphs and the number of reported human TBE cases in the following months, but not in the following year. The hypothesis of the importance of co-feeding of larvae and nymphs for the maintenance of transmission cycle of TBEV in nature is not supported by our findings.

Tick Fauna and Associated Rickettsia, Theileria, and Babesia spp. in Domestic Animals in Sudan (North Kordofan and Kassala States)

Ticks and tick-borne diseases (TBDs) have a major economic impact on animal production worldwide. In the present study, 2410 ticks were collected from January to August 2017 from livestock and other domestic animals in North Kordofan and Kassala, Sudan, for species identification and investigation of Rickettsia spp. and piroplasms, either individually or as pools containing up to 10 ticks by molecular methods. In total, 13 tick species were identified by morphology and 16S rDNA sequencing. The most frequent tick species were Hyalomma impeltatum (24.90%), Rhipicephalus evertsi evertsi (18.84%), Amblyomma lepidum (16.06%), and Rhipicephalus camicasi (12.49%). A pan-Rickettsia real-time PCR revealed an overall minimum infection rate (MIR) with Rickettsia spp. of 5.64% (136 positive tick pools/2410 total ticks). Rickettsia africae and Rickettsia aeschlimannii were the most frequently identified species by sequencing. Furthermore, the following highly pathogenic livestock parasites were detected: Theileria annulata, Theileria lestoquardi, Theileria equi, and Babesia caballi. The present study documented Rhipicephalus afranicus as well as Rickettsia conorii israelensis, Rickettsia massiliae, and Babesia pecorum for the first time in Sudan. These findings are significant for the animal production sector as well as in terms of One Health, as the detected Rickettsia spp. can cause serious illness in humans.

The Red Fox (Vulpes vulpes) as Sentinel for Tick-Borne Encephalitis Virus in Endemic and Non-Endemic Areas

Tick-borne encephalitis (TBE) is one of the most important viral zoonosis caused by a neurotropic arbovirus (TBEV). In Germany, TBE is classified as a notifiable disease with an average of 350 autochthonous human cases annually. The incidence-based risk assessment in Germany came under criticism because every year, a number of autochthonous human TBE cases have been detected outside of the official risk areas. Therefore, it is necessary to find additional parameters to strengthen TBEV surveillance. The aim of this study was to examine red foxes as sentinels for TBE. Thus far, there are no published data about the sensitivity and specificity for serological methods testing fox samples. Hence, we aimed to define a system for the screening of TBEV-specific antibodies in red foxes. A total of 1233 fox sera were collected and examined by ELISA and IIFA and confirmed by micro-NT. The overall seroprevalence of antibodies against TBEV in red foxes from Germany confirmed by micro-NT was 21.1%. The seroprevalence differed significantly between risk (30.5%) and non-risk areas (13.1%), with good correlations to local TBE incidence in humans. In conclusion, serological monitoring of red foxes represents a promising surrogate marker system and may even determine unexpected TBEV foci in regions currently regarded as non-risk areas.

Parasites and vector-borne diseases disseminated by rehomed dogs

The Companion Vector-Borne Diseases (CVBD) World Forum is a working group of leading international experts who meet annually to evaluate current scientific findings and future trends concerning the distribution, pathogenesis, clinical presentation, diagnosis and prevention of vector-borne infections of dogs and cats. At the 14th Symposium of the CVBD World Forum in Trieste, Italy (March 25-28, 2019), we identified the need to (i) bring attention to the potential spread of parasites and vectors with relocated dogs, and (ii) provide advice to the veterinary profession regarding the importance of surveillance and treatment for parasites and vector-borne infections when rehoming dogs. This letter shares a consensus statement from the CVBD World Forum as well as a summary of the problem faced, including the role of veterinary professionals in parasite surveillance, causal issues, and the importance of interdisciplinary cooperation in addressing the problem. To limit opportunities for dissemination of parasites and vectors, whenever possible, underlying problems creating the need for dog rehoming should be addressed. However, when it is necessary to rehome dogs, this should ideally take place in the country and national region of origin. When geographically distant relocation occurs, veterinary professionals have a vital role to play in public education, vigilance for detection of exotic vectors and infections, and alerting the medical community to the risk(s) for pathogen spread. With appropriate veterinary intervention, dog welfare needs can be met without inadvertently allowing global spread of parasites and their vectors.

The envelope protein of tick-borne encephalitis virus influences neuron entry, pathogenicity, and vaccine protection

Background

Tick-borne encephalitis virus (TBEV) is considered to be the medically most important arthropod-borne virus in Europe. The symptoms of an infection range from subclinical to mild flu-like disease to lethal encephalitis. The exact determinants of disease severity are not known; however, the virulence of the strain as well as the immune status of the host are thought to be important factors for the outcome of the infection. Here we investigated virulence determinants in TBEV infection.

Method

Mice were infected with different TBEV strains, and high virulent and low virulent TBEV strains were chosen. Sequence alignment identified differences that were cloned to generate chimera virus. The infection rate of the parental and chimeric virus were evaluated in primary mouse neurons, astrocytes, mouse embryonic fibroblasts, and in vivo. Neutralizing capacity of serum from individuals vaccinated with the FSME-IMMUN® and Encepur® or combined were evaluated.

Results

We identified a highly pathogenic and neurovirulent TBEV strain, 93/783. Using sequence analysis, we identified the envelope (E) protein of 93/783 as a potential virulence determinant and cloned it into the less pathogenic TBEV strain Torö. We found that the chimeric virus specifically infected primary neurons more efficiently compared to wild-type (WT) Torö and this correlated with enhanced pathogenicity and higher levels of viral RNA in vivo. The E protein is also the major target of neutralizing antibodies; thus, genetic variation in the E protein could influence the efficiency of the two available vaccines, FSME-IMMUN® and Encepur®. As TBEV vaccine breakthroughs have occurred in Europe, we chose to compare neutralizing capacity from individuals vaccinated with the two different vaccines or a combination of them. Our data suggest that the different vaccines do not perform equally well against the two Swedish strains.

Conclusions

Our findings show that two amino acid substitutions of the E protein found in 93/783, A83T, and A463S enhanced Torö infection of neurons as well as pathogenesis and viral replication in vivo; furthermore, we found that genetic divergence from the vaccine strain resulted in lower neutralizing antibody titers in vaccinated individuals.

The Spatial Distribution of Dermacentor Ticks (Ixodidae) in Germany-Evidence of a Continuing Spread of Dermacentor reticulatus

In Europe, two tick species of the genus Dermacentor occur, Dermacentor marginatus and Dermacentor reticulatus. When the spatial distribution of both species in Germany was studied comprehensively for the first time in 1976, D. marginatus populations were recorded along the Rhine and Main river valleys in southwestern Germany, while D. reticulatus was very rare. In the last 50 years, however, a considerable range expansion of D. reticulatus has been noted in several European countries. To assess the current distribution of Dermacentor spp. in Germany, citizens were asked to send in ticks suspected to belong to the genus Dermacentor or that were of “unusual” appearance. From February 2019 until February 2020, 3,902 Dermacentor ticks were received in total. Of those, 15.48% (604/3,902) were identified as D. marginatus and 84.24% (3,287/3,902) as D. reticulatus, while 11 specimens could not be identified to species level. The majority of D. reticulatus specimens was collected from dogs (1,212/2,535; 47.12%), while D. marginatus was mostly collected from horses (184/526; 34.98%). Our results confirm that the adults of both Dermacentor species are active all year round. D. reticulatus specimens were sent in from all federal states except the Free and Hanseatic City of Hamburg, while D. marginatus specimens were only received from locations in southwestern Germany. Overall, data obtained from this citizen-science study show that D. reticulatus has significantly expanded its range, especially in northern Germany. Regarding D. marginatus, new locations northwest of the previous range were detected, although the distribution has remained rather stable as compared to D. reticulatus. The spread of D. reticulatus, the vector of Babesia canis, is of major importance for veterinarians and dog owners in terms of canine babesiosis outbreaks or endemization in hitherto B. canis-free areas. Thus, veterinarians and veterinary students need to be informed about the new situation to be able to give adequate advice to dog owners on the extended D. reticulatus range and appropriate control measures.

Results of the first pilot external quality assessment (EQA) scheme for anti-SARS-CoV2-antibody testing

Objectives Assessment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection prevalence and immunity is cornerstones in the fight against COVID-19 pandemic. For pandemic control, reliable assays for the detection of anti-SARS-CoV-2 antibodies are required. This pilot external quality assessment (EQA) scheme aimed to independently assess the participants' clinical performance of anti-SARS-CoV-2 testing, to identify shortcomings in clinical practice and to evaluate the suitability of the scheme format. Methods The EQA scheme consisted of eight serum samples with variable reactivity against SARS-CoV-2 intended for the analysis of anti-SARS-CoV-2 immunoglobulin (Ig)G, IgA, and IgM antibodies. Laboratories reported: (1) results for each sample and the respective method, (2) raw data from replicate testing of each sample. Results The 16 selected pilot EQA participants reported 294 interpreted results and 796 raw data results from replicate testing. The overall error rate for the anti-SARS-CoV-2 IgG, IgA, and IgM tests was 2.7, 6.9, and 16.7%, respectively. While the overall diagnostic specificity was rated as very high, sensitivity rates between 67 and 98% indicate considerable quality differences between the manufacturers, especially for IgA and IgM. Conclusions Even the results reported by the small number of participants indicate a very heterogeneous landscape of anti-SARS-CoV-2 serological testing. Differences of available tests and the individual performance of laboratories result in a success rate of 57.1% with one laboratory succeeding for all three antibody-classes. These results are an incentive for laboratories to participate in upcoming open EQA schemes that are needed to achieve a harmonization of test results and to improve serological testing.

Rapid Detection of SARS-CoV-2 by Low Volume Real-Time Single Tube Reverse Transcription Recombinase Polymerase Amplification Using an Exo Probe with an Internally Linked Quencher (Exo-IQ)

Background

The current outbreak of SARS-CoV-2 has spread to almost every country with more than three million confirmed cases and over two hundred thousand deaths as of April 28, 2020. Rapid first-line testing protocols are needed for outbreak control and surveillance.

Methods

We used computational and manual design to generate a suitable set of reverse transcription recombinase polymerase amplification (RT-RPA) primer and exonuclease probe, internally quenched (exo-IQ) probe sequences targeting the SARS-CoV-2 N gene. RT-RPA sensitivity was determined by amplification of in vitro transcribed RNA standards. Assay selectivity was demonstrated with a selectivity panel of 32 nucleic acid samples derived from common respiratory viruses. To validate the assay against full-length SARS-CoV-2 RNA, total viral RNA derived from cell culture supernatant and 19 nasopharyngeal swab samples (8 positive and 11 negative for SARS-CoV-2) were screened. All results were compared to established RT-qPCR assays.

Results

The 95% detection probability of the RT-RPA assay was determined to be 7.74 (95% CI: 2.87 - 27.39) RNA copies per reaction. The assay showed no cross-reactivity to any other screened coronaviruses or respiratory viruses of clinical significance. The developed RT-RPA assay produced 100% diagnostic sensitivity and specificity when compared to RT-qPCR (n=20).

Conclusion

With a run time of 15 to 20 minutes and first results being available in under 7 minutes for high RNA concentrations, the reported assay constitutes one of the fastest nucleic acid based detection methods for SARS-CoV-2 to date and may provide a simple to use alternative to RT-qPCR for first-line screening at the point of need.

Role of ducks in the transmission cycle of tick-borne encephalitis virus?

Tick-borne encephalitis virus (TBEV), a member of the family Flaviviridae, is the most important tick-transmitted arbovirus in Europe. It can cause severe illnesses in humans and in various animal species. The main mechanism for the spread of TBEV into new areas is considered to be the translocation of infected ticks. To find out whether ducks can function as a natural virus reservoir in addition to serving as passive transport vectors, we carried out an experimental TBEV challenge study to reveal their susceptibility and resulting pathogenesis. Nineteen ducks were inoculated subcutaneously with TBEV strain 'Neudoerfl' and monitored for 21 days. Blood, oropharyngeal and cloacal swabs were collected throughout the experiment and organ samples upon necropsy at the end of the study. All samples were tested for TBEV-RNA by real-time polymerase chain reaction. TBEV-specific antibodies were determined by virus neutralization test and ELISA. Organ samples were examined histopathologically and by immunohistochemistry. The inoculated ducks did not show any clinical symptoms. TBEV-specific RNA was detected in all brain samples as well as in a few blood and swab samples. Moreover, all challenged birds produced TBEV antibodies and showed a mild to severe acute to subacute necrotizing encephalitis. TBEV-specific antigen was detected in the brain of 14 ducks by immunohistochemistry. The short and low viremic phases, as well as the low virus load in tissues, suggest that ducks should not be considered as reservoir hosts. However, due to the high antibody levels, ducks can serve as sentinel species for the detection of natural TBEV foci.