Ticks and Tick-borne Diseases最新文献

The European Centre for Disease Prevention and Control (ECDC) defines a case of tick-borne encephalitis (TBE) as an infection by the TBE virus (TBEV) with clinical manifestations of central nervous system inflammation (e.g., meningitis, encephalitis). To better understand the TBE surveillance landscape, online searches were conducted to determine if cases of TBE, TBEV infection, acute meningitis or encephalitis, or viral meningitis or encephalitis were subject to statutory reporting in European countries in 2023. In countries with statutory reporting, notification responsibility and available information on surveillance-reported cases were determined. The number of TBE cases reported to ECDC were compared with the number of cases recorded in national surveillance reports. Of 44 countries of the Europe Region of the United Nations, 37 (84 %) mandated statutory reporting of cases of TBE, TBEV infection, or acute/viral meningitis/encephalitis. Twenty-six (87 %) of 30 countries with identified surveillance reports recorded TBE cases in 2020–2023. Of these countries, 17 (65 %) required TBE reporting by clinicians and laboratories, 5 (19 %) by clinicians only, and 4 (15 %) by laboratories only. Twenty-four countries reported on TBE cases to ECDC in 2020; however, surveillance for TBE in Europe is heterogeneous. Standardization of TBE surveillance would enhance the understanding of TBE disease burden in Europe.

Revealing interactions between ticks and wild animals is vital for gaining insights into the dynamics of tick-borne pathogens in the natural environment. We aimed to elucidate the factors that determine tick infestation in wild animals by investigating ticks on invasive raccoons (Procyon lotor) in Hokkaido, Japan. We first examined the composition, intensity, and seasonal variation of ticks infesting raccoons in six study areas in Hokkaido from March 2022 to August 2023. In one study area, ticks infesting tanukis (raccoon dog, Nyctereutes procyonoides albus) were collected in May to July in both 2022 and 2023, and questing ticks were collected from the vegetation by flagging every other week in the same period. Next, we screened 17 environmental and host variables to determine factors that affect the number of ticks infesting raccoons using generalized linear (mixed) models. From 245 raccoons, we identified a total of 3,917 ticks belonging to eight species of two genera: the most prominent species were Ixodes ovatus (52.9 %), followed by Haemaphysalis megaspinosa (14.4 %), Ixodes tanuki (10.6 %), and Ixodes persulcatus (9.5 %). Ixodes ovatus was also predominant among questing ticks and ticks infesting tanukis. Although I. tanuki was frequently collected from raccoons and tanukis, it was rarely collected in the field. The variables that significantly affected the infestation on raccoons differed by genus, species and developmental stage of the tick. For instance, the infestation of adult I. ovatus was significantly affected by four variables: night-time temperature during nine days before capturing the raccoon, the size of forest area around the capture site, sex of the raccoon, and sampling season. The first two variables were also responsible for the infestation on raccoons of almost all species and stages of ticks. Our study revealed that the number and composition of ticks infesting raccoons can be affected not only by landscape of their habitats but also by weather conditions in several days before capturing.

Instead of using the Infection and Treatment Method (ITM)-based vaccine, is it possible to control East Coast Fever (ECF) through blocking Theileria parva transmission in ticks and cattle? This review pursues this question. It's over 100 years since Arnold Theiler (1912) first illustrated the natural ITM as a vaccination approach against ECF-cattle disease. The approach entails infecting cattle with live Theileria sporozoites and co-treatment with long-acting tetracycline. Building on the ITM principle, the “Muguga”-cocktail ECF vaccine was developed in the 1970s and it remains the only commercially available-one. Although the vaccine induces cattle-protection, the vaccination approach still raises several drawbacks. Of those, the most outstanding is the vaccine-safety. This is implied because after ITM vaccination, cattle revert to T. parva pathogen reservoirs, therefore, during blood meal-acquisition, the ticks co-ingest T. parva pathogens. Ultimately, the pathogens are further transmitted transstadial; from larvae to nymph and nymph-adults and later re-transmitted to cattle during blood-meal acquisition. Consequently, the vaccine-constituting T. parva strains are introduced and (re) spread in non-endemic/ endemic areas. Precisely, rather than eradicating the disease, the ITM vaccination-approach promotes ECF endemicity. With advent of novel vaccination approaches toward vector and vector-borne disease control, ECF-control based on ITM of vaccination is considered outdated. The review highlights the need for embracing a holistic integrative vaccination approach entailing blocking Theileria pathogen-development and transmission both in the ticks and cattle, and/or the tick-population.

Migratory birds play an important role in transporting ixodid ticks and tick-borne pathogens between continents. During the Boreal spring, migratory birds reach Europe, mainly from sub-Saharan Africa or from northern African countries but not much is known about the diversity and ecology of the ticks they spread. From 2017 to 2022, in the framework of two consecutive projects focused on sampling migratory birds from Africa to Europe, a total of 27 immature Amblyomma ticks were collected from migratory birds, belonging to 8 species, captured on the Island of Ventotene, an important stop-over site in the Mediterranean Sea. In the absence of adult specimens, morphological identification was limited to assigning these ticks to the Amblyomma genus. In this study, sequencing and comparative analysis of three mitochondrial molecular markers (12S rDNA, 16S rDNA, COI) were performed to achieve taxonomic identification. Sequences obtained from Ventotene specimens matched at 100% identity with Amblyomma sparsum. In conclusion, this study documented that immature stages of this species belonging to the Amblyomma marmoreum complex reached the Pontine Islands for six consecutive years. The entry of alien tick species and their potentially transmitted pathogens deserves further study, also in light of the globally ongoing climate change.

We report a case of posterior reversible encephalopathy syndrome in an adult patient fulfilling criteria for proven early Lyme neuroborreliosis.

Alpha-Gal Syndrome (AGS) is a delayed allergic reaction triggered by IgE antibodies targeting galactose-α-1,3-galactose (α-gal), prevalent in red meat. Its global significance has increased, with over 450,000 estimated cases in the United States alone. AGS is linked to tick bites, causing sensitization and elevated α-gal specific IgE levels. However, the precise mechanisms and tick intrinsic factors contributing to AGS development post-tick bites remain unclear. This study aims to characterize the alpha-gal conjugated lipid antigens in Amblyomma americanum (Am. americanum) salivary glands and saliva. Nanospray ionization mass spectrometry (NSI-MS) analysis revealed the identification of α-gal bound lipid antigens in Am. americanum saliva. Additionally, the activation of basophils by extracted alpha-gal bound lipids and proteins provides evidence of their antigenic capabilities.

Ixodes scapularis, the black-legged tick, is a major arthropod vector that transmits the causative agents of Lyme disease and several other pathogens of human significance. The tick midgut is the main tissue involved in blood acquisition and digestion and the first organ to have contact with pathogens ingested through the blood meal. Gene expression in the midgut before, during, and after a blood meal may vary in response to the physiological changes due to blood feeding. A systems biology approach based on RNA and protein sequencing was used to gain insight into the changes in tick midgut transcripts and proteins during blood ingestion (unfed and partially fed) and digestion (1-, 2-, 7-, and 14 days post detachment from the host) by the Ixodes scapularis female ticks. A total of 2,726 differentially expressed transcripts, and 449 proteins were identified across the time points. Genes involved in detoxification of xenobiotics, proteases, protease inhibitors, metabolism, and immunity were differentially expressed in response to blood feeding. Similarly, proteins corresponding to the same groups were also differentially expressed. Nine genes from major gene categories were chosen as potential vaccine candidates, and, using RNA interference, the effect of these gene knockdowns on tick biology was investigated. Knockdown of these genes had variable negative impacts on tick physiology, such as the inability to engorge fully and to produce eggs and increased mortality. These and additional gene targets provide opportunities to explore novel tick control strategies.

Cholesterol is a molecule vital for tick physiology, but ticks cannot synthesize it and rely on dietary cholesterol. Therefore, tick proteins involved in cholesterol absorption and transport, such as the Niemann-Pick type C1 domain-containing (NPC1) proteins, are promising targets for anti-tick vaccine development. The aim of this study was to assess the structure, function, and protective efficacy of the NPC1 orthologues identified previously in the midgut transcriptomes of argasid ticks Ornithodoros erraticus and Ornithodoros moubata. For this purpose, their corresponding cDNA coding sequences were cloned and sequenced, their secondary and 3D structures were predicted, and their function was evaluated through RNAi-mediated gene knockdown and in vitro feeding on blood supplemented with ezetimibe, which inhibits cholesterol binding by NPC1 proteins. Subsequently, the protective efficacy of a recombinant form of NPC1 from O. moubata (rOmNPC1) was tested in a rabbit vaccine trial. While inhibiting cholesterol absorption with ezetimibe resulted in up to 77 % mortality in adult O. moubata, NPC1 gene knockdown and vaccination with rOmNPC1 decreased female reproductive performance in terms of the number and fertility of laid eggs. This study presents the initial molecular and functional insights into NPC1 proteins in soft ticks and supports the hypothesis that disrupting cholesterol metabolism diminishes tick viability and reproduction, rendering Niemann-Pick type C1 domain-containing proteins promising targets for drugs or vaccines.

Nairobi Sheep Disease (NSD) is a typical tick-borne syndrome characterized by severe hemorrhagic gastroenteritis, spontaneous abortion, and a high case fatality rate in small ruminants. The pathogenic agent, Nairobi sheep disease virus (NSDV), has also been associated with human infections, indicating its possible zoonotic potential. Prior to this study, NSDV has been detected from ticks collected in Jilin, Hubei, and Liaoning provinces in China. In the present study, a total of 343 ticks (Haemaphysalis longicornis) were collected in Shandong province, China in 2020, and pooled into 16 libraries. Analysis of the meta-transcriptomic sequencing data identified NSDV strains SDWL07, SDWL08, and SDWL16 from three pools. The SDWL07 and SDWL16 strains were detected from unfed ticks, while SDWL08 was detected from cattle-feeding ticks. Phylogenetic analyses showed higher sequence identities between the three strains and other Chinese NSDV strains than those from India and Kenya. Phylogenetic analyses also revealed that they clustered together and fell within the China lineage, suggesting no potential genetic reassortment among them. In summary, this is the first report of the identification of NSDV in Shandong province, highlighting the continually expanding endemic regions of this pathogen. Surveillance of NSDV should be intensified in China, especially in areas where H. longicornis is endemic.