Search Results (59)

Arthropod-borne viruses (arboviruses) significantly impact human, domestic animal, and wildlife health. While most arboviruses are transmitted to vertebrate hosts by blood-feeding mosquitoes and ticks, a growing body of evidence highlights the importance of other hematophagous arthropods in arboviral transmission. These lesser-known vectors, while often overlooked, can play crucial roles in the maintenance, amplification, and spread of arboviruses. This review summarizes our understanding of hematophagous arthropods, other than mosquitoes and ticks, in arboviral transmission, as well as their associations with non-arboviral viruses. Thirteen arthropod groups are discussed: bat flies, blackflies, cimicids (bat bugs, bed bugs, and bird bugs), Culicoides midges, fleas, hippoboscid flies, lice, mites, muscid flies (including horn flies and stable flies), phlebotomine sandflies, tabanids (including deer flies and horse flies), triatomines, and tsetse flies. Some of these arthropods are regarded as known or likely arboviral vectors, while others have no known role in arbovirus transmission. Particular attention is given to species associated with arboviruses of medical and veterinary significance. As the burden of arboviruses continues to grow, it is critical not to overlook the potential contribution of these lesser-known vectors. Full article

Vector-borne diseases (VBDs) significantly impact global child health, with mosquito-transmitted infections like malaria and arboviruses accounting for a substantial portion of this burden. However, other arthropod-borne diseases—transmitted by vectors such as ticks, fleas, sand flies, lice, and triatomine bugs—also pose serious health risks to children worldwide. This review specifically excludes mosquito-borne diseases to concentrate on these less-discussed yet clinically important pediatric VBDs. We examine their clinical manifestations, diagnostic challenges, and treatment options, highlighting the unique vulnerabilities of children, including immature immune systems, behavioral factors, and communication barriers that can delay diagnosis. Additionally, we explore how environmental and anthropogenic factors, such as climate change and urbanization, are expanding the geographic range of these vectors, leading to the emergence of diseases like Lyme disease and leishmaniasis in new regions. By focusing on non-mosquito VBDs, this review aims to raise awareness and inform healthcare providers and public health practitioners about the comprehensive landscape of pediatric vector-borne diseases. Full article

Rickettsiae are Gram-negative and obligate intracellular bacteria that cause rickettsioses. These pathogens are typically transmitted by arthropod vectors, such as ticks, mesostigmatid mites, and fleas. Rickettsiae are responsible for many emerging infectious diseases worldwide and are the second most frequently reported cause of non-malarial febrile illnesses in Southeast Asia. However, in Malaysia, studies on the prevalence and distribution of rickettsiae have primarily focused on humans, with limited data on these bacteria in vectors and small mammal hosts. Thus, this study aims to investigate the presence of Rickettsia spp. in small mammals and their associated mesostigmatid mites collected from potential rickettsioses areas in Selangor. Animal trapping was conducted across three different ecological study sites comprising a recreational area, agricultural land, and coastal area. A total of 41 small mammals and 363 mesostigmatid mites were collected and identified. Ten percent of the total individual mites were processed for morphological examination, and the remaining mites were then pooled by hosts, with five individual mites per tube, for DNA extraction. The collected samples, comprising blood, animal tissue, and pooled mites, were subjected to DNA extraction and were screened for Rickettsia spp. via nested polymerase chain reaction (PCR), targeting the citrate synthase-encoding gene (gltA) and outer membrane protein B gene (ompB). Interestingly, two pools (3.33%) of Laelaps spp. recovered from Maxomys whiteheadi and Bandicota indica, collected from a recreational area, tested positive for Rickettsia spp. Sequence analysis and phylogenetic tree of the ompB gene revealed the presence of Rickettsia felis in both laelapid mite pools. To our knowledge, this study provides the first molecular detection of R. felis in Laelaps spp. in Malaysia. Full article

Bartonella henselae is an important zoonotic pathogen with a wide range of clinical manifestations in humans. Despite advances in understanding its pathogenesis, there is no broadly applicable laboratory animal model for bartonellosis. This study aimed to assess the potential utility of an experimental model of chronic B. henselae infection using ferrets, a species previously utilized in various human pathogen studies. Six ferrets (n = 6) were divided into three groups: a control group (n = 2), a low-dose infection group (n = 2), and a high-dose infection group (n = 2). The two infection groups were inoculated intradermally with 10⁵ (low dose) and 10⁹ (high dose) CFU/mL B. henselae, respectively. Clinical signs, serological responses, and bacteriological findings were monitored over seven weeks; ferrets were then euthanized and tissues were examined histologically. Only minimal or transient systemic clinical signs and laboratory abnormalities developed in B. henselae inoculated ferrets. The high-dose group seroconverted to B. henselae antigen within two weeks, maintaining elevated titers throughout the study. Histopathological examination revealed that four B. henselae-infected ferrets had notable microscopic inflammatory lesions in the liver parenchyma (3/4), heart (1/4), and brain (1/4); similar lesions were not observed in the tissues of the two control ferrets. Despite the presence of microscopic lesions and seroconversion in the high-dose group, bacteremia was not documented and B. henselae DNA was not successfully amplified by quantitative PCR from lesional organs. This pilot study demonstrated that ferrets may serve as a promising model for investigating B. henselae pathogenesis, diagnosis, treatment, and prevention. Full article

This study reinforces the value of a One Health approach to infectious disease outbreak investigations. After the onset of neuropsychiatric symptoms in their son, our investigation focused on a family composed of a mother, father, two daughters, the son, two dogs, and a rabbit, all with exposures to vectors (fleas and ticks), rescued dogs, and other animals. Between 2020 and 2022, all family members experienced illnesses that included neurological symptoms. Prolonged menorrhagia (130d) in the youngest daughter ultimately resolved following antibiotic administration. One dog was diagnosed with a splenic hematoma and months later spinal histiocytic sarcoma. The father, both daughters, and one dog were seroreactive to multiple Bartonella spp. antigens, whereas the mother and son were not seroreactive. Bartonella quintana DNA was amplified from specimens obtained from all family members. Based upon DNA sequencing, infection with B. quintana was confirmed for the mother and both pet dogs. Bartonella henselae DNA was amplified and sequenced from the youngest daughter, the son, and one dog (co-infected with B. quintana), and from Ctenocephalides felis collected from their pet rabbit. All five family members and one dog were infected with Babesia divergens-like MO-1. Both parents were co-infected with Babesia microti. Droplet digital PCR supported potential infection with a Borrelia species in three family members. This study provided additional case-based evidence supporting the role of stealth Babesia, Bartonella, and Borrelia pathogens as a cause or cofactor in neurological and neuropsychiatric symptoms. We conclude that a One Health investigation approach, particularly for stealth vector borne pathogens such as Babesia, Bartonella, and Borrelia spp., will enhance clinical and epidemiological understanding of these organisms for animal and human health. During outbreak investigations it is critical to document travel and vector exposure histories, symptoms, and pathology in pets and human patients, contact with rescued, wild, or feral animals and perform diagnostic testing that includes family members, pets, and vectors. Full article

Bats and rodents serve as reservoirs for numerous zoonotic pathogens, including species of Trypanosoma and Leishmania. Domestic rats host the flea-transmitted Trypanosoma (Herpetosoma) lewisi, which can be associated with humans, particularly young or immunocompromised individuals. Using Fluorescent Fragment Length Barcoding (FFLB) and phylogenetic analyses based on SSU rRNA sequences, we identified two Herpetosoma species, T. lewisi-like and T. musculi-like species, in bats of different families inhabiting rooftops and peridomestic structures in Brazil (44%, 107 bats examined) and Venezuela (50%, 52 bats examined). These species are typically associated with Rattus spp. (domestic rats) and Mus musculus (house mice), respectively. Furthermore, bats were co-infected with up to five other species, including Trypanosoma dionisii, Trypanosoma cruzi marinkellei, and isolates from the Trypanosoma Neobat clade, all strongly associated with bats, and Trypanosoma cruzi and Trypanosoma rangeli, known to infect various mammals, including humans. Therefore, our findings expand the known host range of Herpetosoma to bats, marking the first report of potential spillover of Herpetosoma trypanosomes from rodents to bats and underscoring the potential for the cross-species transmission of flea-borne trypanosomes. These results highlight the need for a One Health approach to assess infection risks associated with trypanosome spillover from synanthropic rodents and bats to humans. Full article

Rodents play a significant role in the transmission of zoonotic diseases; anthropization has increased human contact with these animals, vectors of infectious agents. However, the processes driving parasitism of hosts remains poorly understood. Yersinia pestis, Rickettsia spp., and Francisella tularensis are three infectious agents transmitted to humans through ectoparasites, with rodents serving as the primary reservoirs. To explore the relationship between both intrinsic and extrinsic factors on host pathogen status, we evaluated heteromyid rodents in the Chihuahuan desert (ChD). From December 2022 to May 2023, we sampled 213 rodents at three locations with different anthropization levels. A total of 103 rodent blood samples, 84 organ samples, and 204 collected ectoparasites were analyzed for molecular detection of infectious agents (Y. pestis, Rickettsia spp., and F. tularensis) with PCR. We captured seven species of rodents (Dipodomys ordii, D. merriami, D. spectabilis, Chaetodipus hispidus, Ch. eremicus, Perognathus flavus, and P. flavescens) and identified one tick (Rhipicephalus sanguineus), two fleas (Meringis altipecten and M. dipodomys) and one louse (Fahrenholzia spp.). Molecular analyses yielded positive for Y. pestis, Rickettsia spp., and negative for F. tularensis. We then modelled the pathogen status as a function of intrinsic (body condition and sex) and extrinsic factors (locality, anthropization level, season, sample type, and parasite-infestation status). We found that non-parasite-infested individuals with better body condition have a higher probability of pathogen infection. Furthermore, we observed that blood samples had a higher probability of detecting pathogen-infected individuals, as compared to spleen or liver samples. Our results offer important insights into host–pathogen interactions and the role of body condition in the pathogen status. Full article

The Trypanosomatidae family encompasses around 24 genera of unicellular protozoans, many of which are transmitted by various hematophagous arthropods, particularly members of the Orders Diptera and Hemiptera. Fleas and ticks—an understudied group of ectoparasites—have been shown to be hosts of a wide and crescent variety of trypanosomatid species. Further, fleas and ticks of companion animals have been particularly neglected in trypanosomatid surveillance despite the proximity to human populations and the anthropophagous habits of many of these arthropods, which can potentially act as vectors of zoonotic trypanosomatids. We aimed to identify the presence, characterize the species, and establish the prevalence of Kinetoplastids, including members of the Trypanosomatidae family, in ectoparasites collected from dogs and humans from Mexico. A total of 537 ectoparasite specimens belonging to six ectoparasite taxa (Amblyomma mixtum, A. tenellum, Ctenocephalides felis felis, Pulex simulans, Rhipicephalus linnaei, and Rh. sanguineus s.s.) were collected from 15 States of Mexico. An 800 bp fragment of the 18S-rDNA gene from kinetoplastids was amplified and sequenced. The presence of two agents (Trypanosoma caninum and Parabodo sp.) was detected in R. linnaei ticks and one (Blechomonas lauriereadi) in the cat flea Ct. felis felis. This is the first record of genetic material of kinetoplastid species in ectoparasites from dogs and humans in Mexico. Full article

Vector-borne infections persist as a significant issue in both human and animal health. Many of the most common vector-borne infections in the USA, especially tick-borne infections, are known to be zoonotic, including Lyme disease, anaplasmosis, and ehrlichiosis, and these infections may also negatively impact the health of infected animals. Convenient patient-side assays for the detection of antibodies to Borrelia burgdorferi, Anaplasma spp., and Ehrlichia spp., and antigen of Dirofilaria immitis have allowed for the generation of robust and large-scale prevalence data in dogs. Data of similar scale and distribution are not available in cats, and most feline prevalence studies have evaluated a small sample size with limited geographic distribution. The objective of this study was to evaluate the prevalence of antibodies to B. burgdorferi, Anaplasma spp., and Ehrlichia spp., and D. immitis antigen among shelter cats across the USA, a population that is presumably at high risk for ectoparasitism and, consequently, exposure to vector-borne infections. In total, 2232 whole blood samples were collected from shelter cats across four regions of the USA—South, Northeast, Midwest, and West—and were evaluated using the Idexx SNAP^® 4Dx^® Test. Ectoparasites were also opportunistically collected from cats during blood collection and morphologically identified. The prevalence of at least one vector-borne infection was 2.60%, and the nationwide prevalence was 1.88% for B. burgdorferi, 0.54% for Anaplasma spp., 0.09% for Ehrlichia spp., and 0.55% for D. immitis. A total of 1120 ectoparasites were collected from 423 cats, including 27 ticks and 1093 fleas. Although the overall prevalence of the pathogens in this survey is relatively low, we observe that there is an increased exposure risk regionally for some agents, with geographic distributions in this study mostly coinciding with established human and canine distributions. Understanding these findings in an assumed non-protected population of cats allows us to extrapolate the risk to pet cats if they are not provided routine veterinary care, including a broad-spectrum parasite prevention program. Full article

Plague is a zoonotic disease caused by Yersinia pestis, and it is endemic in Madagascar. The plague cycle involves wild and commensal rodents and their fleas; humans are an accidental host. Madagascar is the country where plague burden is the highest. Plague re-emerged in Mahajanga, the western coast of Madagascar, in the 1990s and infected populations in the popular and insalubrious zones. Sanitation is considered a primary barrier to infection by excluding pathogens from the environment and reservoirs. Poor housing and hygiene and proximity to rodents and fleas in everyday life are major and unchanged risk factors of plague. The aim of this study was to measure the impact of sanitation on Yersinia pestis bacteria in human and small mammal reservoirs and flea vectors. This study was conducted on 282 households within 14 neighborhoods. Two sessions of sampling were conducted in 2013 and 2016. Small mammals were trapped inside and around houses using live traps. Fleas, blood and spleen were sampled to detect Y. pestis infection and antibodies and determine the level of plague circulation before and after the installation of sanitation in order to assess the impact of sanitation improvement on inhabitant health. Two major types of housing can be described, i.e., formal and informal (traditional), scattered in all the suburbs. Among the small mammals captured, 48.5% were Suncus murinus, and 70% of houses were infested. After sanitation, only 30% of houses remained infested, and most of them were located around the market. Fleas were mostly Xenopsylla cheopis. Before and after intervention, the overall prevalence of fleas was the same (index 4.5) across the 14 suburbs. However, the number of houses with fleas drastically decreased, and the flea index increased significantly in rodent-infested houses. Rodent abundance also decreased from 17.4% to 6.1% before and after intervention, respectively. A serology study highlights that plague is still circulating in Mahajanga, suggesting that small mammals maintain enzootic plague transmission in the city. Full article

Fleas (Siphonaptera) are ectoparasitic hematophagous insects responsible for causing bites and itchy skin conditions in both humans and animals. Furthermore, they can act as vectors of different pathogens of a wide variety of diseases worldwide, including bartonellosis, rickettsiosis, and bubonic plague. Accurate identification of fleas is necessary for the study of their epidemiology, prevention, and control. In addition to traditional morphological classification approaches and molecular biology techniques, geometric morphometrics is increasingly proving to be a useful complementary tool for discriminating between Siphonaptera taxa. With the objective of determining the capacity of this technique to identify and differentiate synanthropic fleas, a principal component analysis was carried out on populations of Ctenocephalides felis, Pulex irritans, and Archaeopsylla erinacei collected in distinct regions of Andalusia (Spain). The analysis carried out on 81 male and female specimens revealed factorial maps that allowed the differentiation of the populations under study, with only partial overlaps that did not prevent their correct identification. Global size differences were also detected, with a slightly larger size in P. irritans males and a bigger size in A. erinacei females. Therefore, the present study emphasizes the role of geometric morphometrics as a useful complementary technique in taxonomic studies of arthropods, especially in the case of flea specimens lacking representative morphological features. Full article

Bat fleas (Insecta: Siphonaptera: Ischnopsyllidae) are highly host-specific ectoparasites distributed worldwide (except Antarctica). The identification of flea species and the detection of flea-borne pathogens plays a significant role not only in veterinary and public health, but also in providing insights into the ecology, behaviour, and geographical distribution of fleas and flea-associated pathogens. The present study aimed to conduct a morphological and molecular identification of fleas collected from Lithuanian bats, as well as to screen for the presence of vector-borne pathogens. A total of 58 flea specimens were collected from bats in Lithuania. Based on morphological analysis, seven flea species were identified (Ischnopsyllus variabilis, I. octactenus, I. simplex, I. elongatus, I. hexactenus, Nycteridopsylla pentactena, and N. eusarca) and screened for the presence of Anaplasma spp., Borrelia spp., Babesia spp., Bartonella spp., Rickettsia spp., and Mycoplasma spp. Molecular analysis of fleas’ COI and 18S rRNA genes showed that the flea species collected from bats are closely genetically related. Bartonella DNA was detected in bat fleas (41.4%). No DNA of Anaplasma, Borrelia, Babesia, Rickettsia, and Mycoplasma was amplified in the tested samples. The Wolbachia sp. was accidentally found in I. elongatus. The phylogenetic analysis of four Bartonella genes (16S-23S rRNA ITS, gltA, rpoB, and groEL) revealed specificity to bats or bats’ ectoparasites. This is the first report about bat flea species and the pathogens in bat fleas in Lithuania. New host records for bat fleas were also reported. This study extends the knowledge about bat fleas and their role as vectors of different pathogens. Full article

The genus Erinaceus is commonly found in rescue centres across the European continent despite the reported decline in some countries. Parasite infections are frequently detected in rescued hedgehogs, leading to increased morbidity and mortality and consequently conditioning their recovery. Some of the most frequent parasites include respiratory nematodes, such as Crenosoma striatum and Capillaria spp., which may lead to important pneumonia. Moreover, some of these agents have zoonotic potential, such as Cryptosporidium spp., Sarcoptes spp., and several species of ticks and fleas, which may transmit different vector-borne pathogens. This review provides a brief guide on hedgehogs’ internal and external parasitology, as well as some suggestions for diagnosis and treatment that are relevant for wildlife veterinarians, biologists and other researchers. Full article

This overview initially describes insect immune reactions and then brings together present knowledge of the interactions of vector insects with their invading parasites and pathogens. It is a way of introducing this Special Issue with subsequent papers presenting the latest details of these interactions in each particular group of vectors. Hopefully, this paper will fill a void in the literature since brief descriptions of vector immunity have now been brought together in one publication and could form a starting point for those interested and new to this important area. Descriptions are given on the immune reactions of mosquitoes, blackflies, sandflies, tsetse flies, lice, fleas and triatomine bugs. Cellular and humoral defences are described separately but emphasis is made on the co-operation of these processes in the completed immune response. The paper also emphasises the need for great care in extracting haemocytes for subsequent study as appreciation of their fragile nature is often overlooked with the non-sterile media, smearing techniques and excessive centrifugation sometimes used. The potential vital role of eicosanoids in the instigation of many of the immune reactions described is also discussed. Finally, the priming of the immune system, mainly in mosquitoes, is considered and one possible mechanism is presented. Full article

Despite the large number of studies on rodent ectoparasites—most of them vectors of epidemiologically important pathogens—infestation patterns remain poorly understood in various ecological contexts, such as the highly patchy agricultural landscapes. We aimed to relate the infestation of rodents to temporal, habitat, and host variables. We assessed the difference in parasite prevalence and mean abundance depending on host sex, age, and body weight, season, and land use intensity. Furthermore, we analysed the effect of host species abundance and the differential responses of parasites in main and minor host species. The field survey was conducted in a rural landscape in southern Transylvania (Romania) between June and September 2010–2011. We live-trapped small mammals, collected the ticks and fleas, and recorded the presence of lice and mites. Overall, we found the same infestation patterns largely reported in the literature: higher prevalence and mean abundance in heavier adult males, significant seasonality and differences among host species, and evidence of the dilution effect. The uniqueness of our study system was the negative effect of the land use intensity on the prevalence and mean abundance of parasites, explained by the highly patchy mosaic landscape. Full article