Parasites & Vectors最新文献

Background: Sugar feeding is an essential aspect of mosquito biology that may be exploited for mosquito control by adding insecticides to sugar attractants, so-called 'attractive targeted sugar baits' (ATSBs). To optimize their effectiveness, ATSB products need to be maximally attractive at both short and long range and induce high levels of feeding. This study aimed to assess the attractiveness and feeding success of Anopheles mosquitoes exposed to attractive sugar baits (ASBs).

Method: Experiments were conducted in 2 × 5 × 2-m cages constructed within the semi-field systems (SFS) at Ifakara Health Institute, Bagamoyo, Tanzania. Male and female Anopheles gambiae s.s. and An. funestus s.s. mosquitoes were exposed to either 20% sucrose or different ASB station prototypes produced by Westham Co. in either (1) no-choice experiments or (2) choice experiments. Mosquitoes were exposed overnight and assessed for intrinsic or relative olfactory attraction using fluorescent powder markers dusted over the ASB stations and 20% sucrose and for feeding using uranine incorporated within the bait station and food dye in 20% sucrose controls.

Results: Both male and female An. gambiae and An. funestus mosquitoes were attracted to the ASBs, with no significant difference between the sexes for each of the experiments conducted. Older mosquitoes (3-5 days) were more attracted to the ASBs (OR = 8.3, [95% CI 6.6-10.5] P < 0.001) than younger mosquitoes (0-1 day). Similarly, older mosquitoes responded more to 20% sucrose (OR = 4.6, [3.7-5.8], P < 0.001) than newly emerged Anopheles. Of the four prototypes tested, the latest iteration, ASB prototype v1.2.1, showed the highest intrinsic attraction of both Anopheles species, attracting 91.2% [95% CI 87.9-94.5%]. Relative to ATSB v1.1.1, the latest prototype, v.1.2.1, had higher attraction (OR = 1.19 [95% CI 1.07-1.33], P < 0.001) and higher feeding success (OR = 1.71 [95% CI 1.33-2.18], P < 0.001).

Conclusions: Data from these experiments support using ASBs v1.2.1, deployed in large-scale epidemiological trials, as it is the most attractive and shows the highest feeding success of the Westham prototypes tested. The findings indicate that future bioassays to evaluate ATSBs should use mosquitoes of both sexes, aged 3-5 days, include multiple species in the same cage or chamber, and utilize both non-choice and choice tests with a standard comparator.

Background: Aedes albopictus, the Asian tiger mosquito, which is listed among the world's 100 most dangerous invasive species, is the main vector of chikungunya, dengue and Zika viruses. This mosquito species has rapidly dispersed and invaded much of the globe assisted by its life history traits and high propagule pressure driven by human activities. Aedes albopictus is currently widespread across mainland Europe and the Mediterranean region, including the islands. Cyprus remained free of Ae. albopictus until October 2022, when specimens were recorded for the first time in Limassol district, including the port area. Understanding the processes associated with the introduction, expansion and establishment of this vector in Cyprus is of primary importance to mitigate its dispersal on the island, and to implement control methods to prevent disease outbreaks. A genetic analysis of these invasive specimens collected in Limassol district and in areas from the Central Mediterranean was performed to obtain a genetic portrait of the demographic history of the invasive mosquitoes on Cyprus.

Methods: We applied highly polymorphic simple sequence repeat (SSR) markers to the Ae. albopictus mosquitoes collected in Cyprus and to specimens from Italy, France, Switzerland, the Balkans, Greece and Turkey to construct an SSR individual genotype dataset that would enable the invasion pattern of Ae. albopictus in Cyprus to be traced. Bayesian clustering analyses using STRUCTURE and BayesAss version 3 were employed to derive information on the degree of ancestry among Cypriot and Mediterranean mosquitoes and on recent mosquito movements both within Cyprus and between Cyprus and the Central Mediterranean areas.

Results: The Cypriot mosquitoes appear to be highly polymorphic with no signs of genetic drift due to recent founder effects. An ongoing mosquito dispersal within the Limassol district was detected, suggesting the presence of established, hidden adventive populations. These mosquitoes share a high degree of ancestry with those in the Balkans and parts of northern Italy that border the Adriatic Sea.

Conclusions: Considering the trade connections of Limassol port, Cyprus with the Balkans and the Adriatic Italian region, we hypothesise that these areas may be involved in the incursion of Ae. albopictus into Cyprus. As the Balkan and Italian mosquitoes display high competence for CHIKV, questions arise about possible arbovirus outbreaks in Cyprus and highlight the need to implement surveillance and control measures.

Background: Schistosomiasis, which is caused by the parasite Schistosoma mansoni as well as other species of the trematode genus Schistosoma, leads to chronic inflammation and finally to liver fibrosis. If untreated, the disease can cause life-threatening complications. The current treatment of schistosomiasis relies on a single drug, praziquantel (PZQ). However, there is increasing concern about emerging resistance to PZQ due to its frequent use.

Methods: To identify potential alternative drugs for repurposing, the Open Global Health Library (OGHL) was screened in vitro, using two different screening workflows at two institutions, against adult S. mansoni couples and newly transformed schistosomula. This was followed by confirmation of the effects of the lead structures against adult worms.

Results: In vitro screening at one of the institutions identified two fast-acting substances affecting worm physiology (OGHL00022, OGHL00121). The effects of the two lead structures were investigated in more detail by confocal laser scanning microscopy and 5-ethynyl 2´-deoxyuridine (EdU) assays to assess morphological effects and stem cell effects. Both substances showed negative effects on stem cell proliferation in S. mansoni but no further morphological changes. The EC₅₀values of both compounds were determined, with values for compound OGHL00022 of 5.955 µM for pairing stability, 10.88 µM for attachment, and 18.77 µM for motility, while the values for compound OGHL00121 were 7.088 µM for pairing stability, 8.065 µM for attachment, and 6.297 µM for motility 24 h after treatment. Furthermore, S. mansoni couples were treated in vitro with these two lead structures simultaneously to check for additive effects, which were found with respect to reduced motility. The second in vitro screening, primarily against newly transformed schistosomula and secondarily against adult worms, identified four lead structures in total (OGHL00006, OGHL00022, OGHL00169, OGHL00217). In addition, one of the tested analogues of the hits OGHL00006, OGHL00169, and OGHL00217 showed effects on both stages.

Conclusions: In two independent in vitro screening approaches against two stages of S. mansoni one common interesting structure with rapid effects was identified, OGHL00022, which provides opportunities for further development.

Background: Tick hemolymph is a sterile fluid that carries nutrients to maintain tick health. The hemolymph creates a hostile environment for invaders including the destruction of microorganisms by its circulating hemocytes. However, Babesia parasites escape and disseminate to other organs through the hemolymph to continue their transmission life cycle. Still, it is unknown how tick hemocytes respond to B. bovis or B. bigemina infection. In this study, we conducted a transcriptomic analysis of hemocytes from female Rhipicephalus microplus ticks infected with Babesia parasites to understand how gene expression changes during parasite infection.

Methods: During Babesia acute infection, female R. microplus ticks were fed on bovines to acquire parasites. Engorged females were collected and incubated to develop Babesia kinetes in tick hemolymph. The hemolymph was examined to identify ticks that were highly infected with Babesia kinetes. Hemocyte cells were collected from replete female ticks infected with Babesia bovis or Babesia bigemina to perform high-throughput RNA-sequencing (RNA-Seq) analysis.

Results: This study identified major changes in the gene profile of tick hemocytes during Babesia infection. The main groups of hemocyte genes that were altered during Babesia infection were associated with metabolism, immunity, and cytoskeletal rearrangement. Upregulated genes were mainly involved in defense mechanisms, while downregulated genes were related to cell proliferation and apoptosis. However, the expression of hemocyte genes varied among Babesia species' infections, and it reflected the changes that occurred in the tick's physiology, including growth, reproduction, and skeletal muscle development.

Conclusions: The differential gene expression of R. microplus hemocytes revealed that genes highly regulated upon Babesia infection were related to metabolism, tick immunity, cell growth, apoptosis, development, metabolism, and reproduction. Additional research is necessary to further define the genes that exhibited varying expression levels in hemocytes during the infection. The findings of this study will enhance our understanding on how Babesia parasites survive in the hostile environment of ticks and perpetuate their transmission cycle, ultimately contributing to the spread of bovine babesiosis.

Background-objective: Trichinella spiralis drug development and control need an objective high throughput system to assess first stage larvae (L1) viability. YOLOv5 is an image recognition tool easily trained to count muscular first stage larvae (L1) and recognize morphological differences. Here we developed a semi-automated system based on YOLOv5 to capture photographs of 96 well microplates and use them for L1 count and morphological damage evaluation after experimental drug treatments.

Material and methods: Morphological properties were used to distinguish L1 from debris after pepsin muscle digestion and distinguish healthy (serpentine) or damaged (coiled) L1s after 72 h untreated or treated with albendazole or mebendazole cultures. An AxiDraw robotic arm with a smartphone was used to scan 96 well microplates and store photographs. Images of L1 were manually annotated, and augmented based on exposure, bounding, blur, noise, and mosaicism.

Results: A total of 1309 photographs were obtained that after L1 labeling and data augmentation gave 27478 images. The final dataset of 12571 healthy and 14907 affected L1s was used for training, testing, and validating in a ratio of 70/20/10 respectively. A correlation of 92% was found in a blinded comparison with bare-eye assessment by experienced technicians.

Conclusion: YOLOv5 is capable of accurately counting and distinguishing between healthy and affected L1s, thus improving the performance of the assessment of meat inspection and potential new drugs.

Background: Bison (Bison bison) and cattle (Bos taurus) are closely related (can interbreed) and they also share many parasites. Cattle are commonly infected with one or more of the eight named Sarcocystis species: Sarcocystis hirsuta, S. cruzi, S. hominis, S. bovifelis, S. heydorni, S. bovini, S. sigmoideus and S. rommeli. Among these, the full life-cycle is known only for S. cruzi. Sarcocystis cruzi (transmitted via canids) is recognized as the most pathogenic Sarcocystis species, causing abortion, low milk yield and poor body growth. It has been experimentally cross-transmitted from cattle to bison and vice versa.

Methods: We tested 200 bison tongues from three commercial sources (farms) (Nebraska #141; South Dakota #36; New Jersey and Pennsylvania #23). Frozen tongues were purchased and examined for Sarcocystis infection using light microscopy, histology and quantitative PCR (qPCR) targeting 18S ribosomal DNA (18S rRNA) of S. cruzi. Lesions associated with degenerating sarcocysts were studied. The intensity of Sarcocystis infection in histological sections was quantitated.

Results: Sarcocystis cruzi-like infections were detected in 129 of 141 (91.5%) tongues from Nebraska, 36 of 36 (100%) tongues from South Dakota and two of 23 (8.6%) tongues from New Jersey and Pennsylvania. Sarcocysts were detected in histological sections stained with hematoxylin and eosin in 167 of 200 samples. Light microscopy examination revealed that the sarcocysts had thin walls (< 1 µm thick) and appeared to be S. cruzi. However, in two samples, sarcocysts had thicker walls measuring up to 2.3 µm wide and 154 µm long and the sarcocyst wall was not striated; these two samples could not be characterized further. In three tongues, degenerating sarcocysts were recognized; two of these were associated with thick-walled sarcocysts. Molecularly, S. cruzi from bison was identical to that in cattle.

Conclusions: In the present study of bison tongues, S. cruzi was the only species identified in bison using both molecular and morphological methods. An unidentified species of Sarcocystis found in two bison samples needs further study.

Background: The mosquito midgut is crucial for digestion and immune interactions. It produces several immune factors that protect the organ from invading pathogens and can limit their propagation. Studies on mosquito midgut transcriptome following pathogen exposure have revealed the presence of non-canonical immune genes, such as ABC transporters, whose function in insect immunity remains unexplored. Therefore, this study focuses on identifying and characterising the immune role of ABC transporters in the midgut of Aedes aegypti, a primary arboviral vector.

Methods: To identify the midgut-expressed ABC transporters, the mosquitoes were challenged with a mixture of gram-negative (Escherichia coli) and gram-positive (Micrococcus luteus) bacteria, and the expression of all ABC transporters was analysed with PCR using gene-specific primers. Furthermore, the transcriptional alterations of midgut ABC transporters were explored at different time points upon a thoracic nano-injection (systemic challenge) or infectious blood meal (local challenge) of the bacterial mixture through quantitative real-time PCR (qPCR), and one gene was selected for RNAi-mediated gene silencing and its role assessment in midgut immune responses.

Results: The expression of all 48 microbial-induced midgut-expressing Ae. aegypti ABC transporter genes upon systemic or local bacterial challenges was analyzed. Based on the transcriptomic data and potential immune expression similar to the well-known immune gene defensin, AaeABCG3 was selected for RNAi-mediated gene silencing and characterization. The AaeABCG3 gene silencing exhibited a significant reduction of midgut bacterial load through the induction of nitric oxide synthase (NOS) in sugar-fed and systemic bacterial-challenged mosquitoes. In contrast, midgut bacterial load was significantly regulated by induction of defensin A and cecropin G in the late hours of local bacterial challenges in AaeABCG3-silenced mosquitoes.

Conclusions: The silencing of AaeABCG3 modulated the mosquito midgut immune response and disturbed the midgut microbiota homeostasis. The systemic immune responses of AaeABCG3-silenced mosquitoes were influenced by the JAK-STAT pathway with no induction of Toll and IMD immune pathways. Interestingly, Toll and IMD immune pathways actively participated in the late hours of local bacterial challenges, suggesting that the route of infection influences these immune responses; however, the molecular mechanism behind these phenomena still needs to be explored. Overall, this work provides significant insight into the importance of ABC transporters in mosquito immunity.

Mosquitoes are responsible for the transmission of numerous pathogens, including Plasmodium parasites, arboviruses and filarial worms. They pose a significant risk to public health with over 200 million cases of malaria per annum and approximately 4 billion people at risk of arthropod-borne viruses (arboviruses). Mosquito populations are geographically expanding into temperate regions and their distribution is predicted to continue increasing. Mosquito symbionts, including fungi, bacteria and viruses, have desirable traits for mosquito disease control including spreading horizontally and vertically through mosquito populations and potentially colonising multiple important vector species. Paratransgenesis, genetic modification of mosquito symbionts with effectors to target the pathogen rather than the vector, is a promising strategy to prevent the spread of mosquito-borne diseases. A variety of effectors can be expressed but venom toxins are excellent effector candidates because they are target specific, potent and stable. However, the only toxins to be explored in mosquito paratransgenesis to date are scorpine and mutated phospholipase A2. To enhance the scope, effectiveness and durability of paratransgenesis, an expanded arsenal of effectors is required. This review discusses other potential toxin effectors for future paratransgenesis studies based on prior in vitro and in vivo antiparasitic and antiviral studies and highlights the need for further research and investment in this area. In terms of mosquito-borne diseases, paratransgenesis strategies have been developed to target Plasmodium. We postulate the potential to apply this principle to target arboviruses using antiviral toxin effectors.

Background: Amebiasis represents a significant global health concern. This is especially evident in developing countries, where infections are more common. The primary diagnostic method in laboratories involves the microscopy of stool samples. However, this approach can sometimes result in the misinterpretation of amebiasis as other gastroenteritis (GE) conditions. The goal of the work is to produce a machine learning (ML) model that uses laboratory findings and demographic information to automatically predict amebiasis.

Method: Data extracted from Jordanian electronic medical records (EMR) between 2020 and 2022 comprised 763 amebic cases and 314 nonamebic cases. Patient demographics, clinical signs, microscopic diagnoses, and leukocyte counts were used to train eight decision tree algorithms and compare their accuracy of predictions. Feature ranking and correlation methods were implemented to enhance the accuracy of classifying amebiasis from other conditions.

Results: The primary dependent variables distinguishing amebiasis include the percentage of neutrophils, mucus presence, and the counts of red blood cells (RBCs) and white blood cells (WBCs) in stool samples. Prediction accuracy and precision ranged from 92% to 94.6% when employing decision tree classifiers including decision tree (DT), random forest (RF), XGBoost, AdaBoost, and gradient boosting (GB). However, the optimized RF model demonstrated an area under the curve (AUC) of 98% for detecting amebiasis from laboratory data, utilizing only 300 estimators with a max depth of 20. This study highlights that amebiasis is a significant health concern in Jordan, responsible for 17.22% of all gastroenteritis episodes in this study. Male sex and age were associated with higher incidence of amebiasis (P = 0.014), with over 25% of cases occurring in infants and toddlers.

Conclusions: The application of ML to EMR can accurately predict amebiasis. This finding significantly contributes to the emerging use of ML as a decision support system in parasitic disease diagnosis.

Background: In recent years, cases of leishmaniosis have been described in animals housed in captivity in zoos in Spain [Bennett's wallaby (Macropus rufogriseus rufogriseus), orangutan (Pongo pygmaeus pygameus), and European otter (Lutra lutra)]. Some of these zoological parks are in endemic areas for both human and animal leishmaniosis, thus it should be very important to include this zoonosis in the differential diagnosis.

Methods: The study was carried out in two zoological parks in Madrid, Madrid Zoo and Faunia, and analyzed seven meerkats. Serological tests [rK-39 and enzyme-linked immunosorbent assay (ELISA)] and molecular tests [nested polymerase chain reaction (PCR) and real-time PCR] were performed to detect Leishmania DNA. Additionally, an entomological study was carried out in both zoological parks, with molecular tests performed on female Phlebotomus perniciosus sand flies to determine their blood meal source and detect Leishmania DNA.

Results: Two meerkats were positive for L. infantum. A 9-year-old male from the Madrid Zoo died suddenly, showing pale mucous membranes and bilateral noninflammatory alopecia and hyperpigmentation in the lateral area of the eyes. Positive results were obtained in serology, nested PCR, and real-time PCR (blood, conjunctival and oral swabs, hair, spleen, lymph node, liver, kidney, and skin), as well as numerous amastigotes in the liver and kidney tissue samples. The other meerkat, a 12-year-old male from Faunia that is still alive, presented an alopecic lesion at the base of the tail. Positive results were obtained by nested and real-time PCR from different tissues such as blood, hair, oral, and conjunctival swabs. It was treated with oral allopurinol (25 mg/kg) and miltefosine (2 mg/kg), but the molecular diagnosis remained positive after 8 months, regarding it as a mild stage of the disease. The rest of the tested meerkats were negative. The presence of P. perniciosus phlebotomine sand flies was also detected in both zoos. Although no L. infantum DNA was detected in any of sand flies analyzed, it was determined that their food sources were rabbits and humans.

Conclusions: To our knowledge, this study describes, for the first time, the detection and infection by L. infantum in meerkats (Suricata suricatta).