Emerging roles of non-coding RNAs in vector-borne infections.

Non-coding RNAs (ncRNAs) are nucleotide sequences that are known to assume regulatory roles previously thought to be reserved for proteins. Their functions include the regulation of protein activity and localization and the organization of subcellular structures. Sequencing studies have now identified thousands of ncRNAs encoded within the prokaryotic and eukaryotic genomes, leading to advances in several fields including parasitology. ncRNAs play major roles in several aspects of vector-host-pathogen interactions. Arthropod vector ncRNAs are secreted through extracellular vesicles into vertebrate hosts to counteract host defense systems and ensure arthropod survival. Conversely, hosts can use specific ncRNAs as one of several strategies to overcome arthropod vector invasion. In addition, pathogens transmitted through vector saliva into vertebrate hosts also possess ncRNAs thought to contribute to their pathogenicity. Recent studies have addressed ncRNAs in vectors or vertebrate hosts, with relatively few studies investigating the role of ncRNAs derived from pathogens and their involvement in establishing infections, especially in the context of vector-borne diseases. This Review summarizes recent data focusing on pathogen-derived ncRNAs and their role in modulating the cellular responses that favor pathogen survival in the vertebrate host and the arthropod vector, as well as host ncRNAs that interact with vector-borne pathogens.

Drivers of Rift Valley fever epidemics in Madagascar.

Rift Valley fever (RVF) is a vector-borne viral disease widespread in Africa. The primary cycle involves mosquitoes and wild and domestic ruminant hosts. Humans are usually contaminated after contact with infected ruminants. As many environmental, agricultural, epidemiological, and anthropogenic factors are implicated in RVF spread, the multidisciplinary One Health approach was needed to identify the drivers of RVF epidemics in Madagascar. We examined the environmental patterns associated with these epidemics, comparing human and ruminant serological data with environmental and cattle-trade data. In contrast to East Africa, environmental drivers did not trigger the epidemics: They only modulated local Rift Valley fever virus (RVFV) transmission in ruminants. Instead, RVFV was introduced through ruminant trade and subsequent movement of cattle between trade hubs caused its long-distance spread within the country. Contact with cattle brought in from infected districts was associated with higher infection risk in slaughterhouse workers. The finding that anthropogenic rather than environmental factors are the main drivers of RVF infection in humans can be used to design better prevention and early detection in the case of RVF resurgence in the region.

[Laboratory diagnostic of human babesiosis.]

Human babesiosis caused by parasitic protozoan Babesia spp. is sporadic zoonotic vector-borne infection. The course of babesiosis and prognosis depend on the type of pathogen and on the patient's immunological status. Significance this disease is a severe, often fatal course with immunocompromissed patients resembling complicated falciparum malaria. In Europe to date, more than 50 cases of confirmed human babesiosis have been reported in most cases caused by Babesia divergens. Possible there are unrecognized cases. Pathogen is an obligate intraerythrocyte parasite of vertebrate animals. The organism is transmitted from animal to man through bite of Ixodidae tick. Asexual reproduction of the parasite occurs in a vertebrate host. The pathogenesis of babesiosis is caused by the destruction of host cells. Intensive haemolysis of red blood cells leads to the development of haemolytic anemia, haematuria, jaundice, and polyorgan failure may develop. The clinical manifestations of the disease are nonspecific. Detection of intraerythrocyte parasites in blood smears stained Gimsa-Romanovsky confirms the proposed diagnosis. Blood smears and some laboratory signs from fatal cases were analyzed in the Reference-centre of E. I. Martsinovskii Institute. Original microphotographs B. divergens are shown. The main morphological forms of the parasite are shown. In addition to the well-known tetrades of parasites «Maltese Cross¼, for the first time, the parasites dividing into 6 interconnected trophozoites - "sextet" - were found. Originally, the invasion of Babesia in a normoblast is shown. An unusually high multiple invasion (14 parasites) of erythrocytes is noted. Because the patients, initially, were incorrectly diagnosed with malaria, the differential diagnosis of Babesia with Plasmodium is described step-by-step. It is important, since the treatment with antimalarial drugs is ineffective. Deviation laboratory signs are discussed. Complex morphological characteristics allowed us to speciated the parasites as B. divergens. DNA was detected in the sample with specific primers Bab di hsp70F/Bab di hsp70R and the probe Bab di hsp70P. The sequence demonstrated 99-100% and 98% similarity to the 18S rRNA gene fragment of B. divergence and Babesia venatorum, respectively. Molecular biological and serological methods of laboratory diagnosis of babesiosis are considered.

Orientia tsutsugamushi Is Highly Susceptible to the RNA Polymerase Switch Region Inhibitor Corallopyronin A In Vitro and In Vivo.

Scrub typhus is a potentially lethal infection caused by the obligate intracellular bacterium Orientia tsutsugamushi Reports on the emergence of doxycycline-resistant strains highlight the urgent need to develop novel antiinfectives against scrub typhus. Corallopyronin A (CorA) is a novel α-pyrone compound synthesized by the myxobacterium Corallococcus coralloides that was characterized as a noncompetitive inhibitor of the switch region of the bacterial RNA polymerase (RNAP). We investigated the antimicrobial action of CorA against the human-pathogenic Karp strain of O. tsutsugamushiin vitro and in vivo The MIC of CorA against O. tsutsugamushi was remarkably low (0.0078 µg/ml), 16-fold lower than that against Rickettsia typhi In the lethal intraperitoneal O. tsutsugamushi mouse infection model, a minimum daily dose of 100 µg CorA protected 100% of infected mice. Two days of treatment were sufficient to confer protection. In contrast to BALB/c mice, SCID mice succumbed to the infection despite treatment with CorA or tetracycline, suggesting that antimicrobial treatment required synergistic action of the adaptive immune response. Similar to tetracycline, CorA did not prevent latent infection of O. tsutsugamushiin vivo However, latency was not caused by acquisition of antimicrobial resistance, since O. tsutsugamushi reisolated from latently infected BALB/c mice remained fully susceptible to CorA. No mutations were found in the CorA-binding regions of the ß and ß' RNAP subunit genes rpoB and rpoC Inhibition of the RNAP switch region of O. tsutsugamushi by CorA is therefore a novel and highly potent target for antimicrobial therapy for scrub typhus.

Epidemiologic Survey of Japanese Encephalitis Virus Infection, Tibet, China, 2015.

We investigated Japanese encephalitis virus (JEV) prevalence in high-altitude regions of Tibet, China, by using standard assays to test mosquitoes, pigs, and humans. Results confirmed that JEV has spread to these areas. Disease prevention and control strategies should be used along with surveillance to limit spread of JEV in high-altitude regions of Tibet.

Pregnant Women Hospitalized with Chikungunya Virus Infection, Colombia, 2015.

In 2015 in Colombia, 60 pregnant women were hospitalized with chikungunya virus infections confirmed by reverse transcription PCR. Nine of these women required admission to the intensive care unit because of sepsis with hypoperfusion and organ dysfunction; these women met the criteria for severe acute maternal morbidity. No deaths occurred. Fifteen women delivered during acute infection; some received tocolytics to delay delivery until after the febrile episode and prevent possible vertical transmission. As recommended by a pediatric neonatologist, 12 neonates were hospitalized to rule out vertical transmission; no clinical findings suggestive of neonatal chikungunya virus infection were observed. With 36 women (60%), follow-up was performed 1 year after acute viremia; 13 patients had arthralgia in >2 joints (a relapse of infection). Despite disease severity, pregnant women with chikungunya should be treated in high-complexity obstetric units to rule out adverse outcomes. These women should also be followed up to treat potential relapses.

The role of heterogeneity on the invasion probability of mosquito-borne diseases in multi-host models.

Heterogeneity in transmission and stochastic events can play a significant role in shaping the epidemic dynamics of vector-borne infections, especially in the initial phase of an outbreak. In this work, by using multi-type branching process methodologies, we assess how heterogeneities in transmission among a large number of host groups can affect the invasion probabilities of a mosquito-borne disease. We show with both analytical and numerical methods that heterogeneities in transmission can shape the invasion probabilities differently from how they affect the basic reproduction number (R0). In particular, we find that, while R0 always increases with the heterogeneity, the invasion probability after the introduction of infected hosts can decrease with the increase of transmission heterogeneity, even approaching zero when the number of host groups is very large. In addition, we show that the invasion probability via infected vectors is always larger than via infected hosts when heterogeneous transmission is sufficiently high. Our findings suggest that, for multi-species infections (e.g. West Nile fever and Rift Valley fever) or for single-species infections with patchy host distribution, the introduction of primary infected vectors may represent a higher risk for major outbreaks occurrence than introductions of infected hosts.

Vector-Borne Pathogens in Stray Cats in Eastern Germany (Thuringia).

Bacterial, protozoal, and viral vector-borne pathogens (VBPs) can cause infections in cats. There is little information on feline VBP prevalence in Germany. Stray cats are frequently exposed to vectors but receive no veterinary care. The aim of this study was to determine the prevalence of selected VBPs in stray cats. EDTA blood and serum samples were taken from apparently healthy stray cats during a spay/neuter campaign in the federal state of Thuringia. Overall, 11/50 (22%) and 32/50 (64%) cats tested positive for at least one VBP by direct and indirect detection methods, respectively. PCR testing of EDTA blood detected hemotropic Mycoplasma spp. in 12% of cats, Hepatozoon spp. in 10%, and Anaplasma phagocytophilum in 4%. PCR testing for Rickettsia spp. and piroplasms was negative. IFAT on serum samples showed 46% of cats had detectable antibodies for Bartonella spp., 30% for Rickettsia spp., and 16% for A. phagocytophilum. The cats were additionally tested for feline coronavirus, FIV, and FeLV to identify potential risk factors for pathogen contact and/or infections. No correlation between FIV and FeLV status and VBP positivity was detected. Anaplasma phagocytophilum, Rickettsia spp., and Bartonella spp. have zoonotic potential, and surveillance is recommended in the context of the One Health approach.

Feline leishmaniosis with focus on ocular manifestation: a case report.

BACKGROUND: In Europe, feline leishmaniosis is commonly caused by Leishmania infantum. There is little knowledge regarding pathogenesis, ocular manifestations and long-term follow-ups in cats with leishmaniosis. FINDINGS: A 6-year-old female, spayed European Shorthair cat was imported from Spain to Germany 2 years prior to its first clinical presentation. The cat showed lethargy, weight loss, ulcerative lesions on the front limbs and high-grade chronic uveitis. The diagnosis of L. infantum infection was based on the cytological finding of amastigotes in skin lesions, positive qPCR of EDTA-blood and positive PCR of a cyto-brush sample from the conjunctiva. Supportive findings included positive serology by IFAT, serum protein capillary electrophoresis with peaks in alpha2- and gamma-globulin sections and marked elevation of SAA. Enucleation had to be performed on day 288 on both eyes because of blindness, glaucoma and high-grade uveitis. Histologically, high numbers of Leishmania spp. amastigotes were found in histiocytes. IFAT and PCR were positive in the aqueous humor in both eyes, respectively. Feline leukemia virus antigen and feline immunodeficiency virus antibody testings were positive. Hematological and biochemical results revealed mild leukocytosis with lymphocytosis, monocytosis and eosinopenia as well as marked elevation of SAA and hyperglobulinemia. The cat was treated with allopurinol, responded well and was still alive at follow-up on day 288 after first presentation. However, enucleation was necessary because of refractory glaucoma and uveitis.  CONCLUSION: For the first time, ocular evidence of Leishmania IgG antibodies was demonstrated in the aqueous humor of both eyes in cats. There is limited knowledge about the pathogenesis, treatment options and outcomes in cats infected with L. infantum. This case report supports the hypothesis that immunosuppression increases the risk of clinical signs of leishmaniasis in cats. Alpha2- and gamma-globulin peaks in serum protein capillary electrophoresis are supportive criteria for the diagnosis of L. infantum infection. SAA is valuable for monitoring. Regarding ophthalmology, uveitis and glaucoma may have a poor prognosis.

Molecular detection of Hepatozoon species infections in domestic cats living in Germany.

OBJECTIVES: Three species of protozoal Hepatozoon species (H felis, H canis and H silvestris) are known to infect cats in Europe. The objective of this study was to determine the prevalence of Hepatozoon species in samples from cats living in Germany that were submitted to a veterinary laboratory. METHODS: The study included cats tested for Hepatozoon species by PCR between 2007 and 2020 by the Laboklin laboratory. Travel history and haematological results were documented for cats with positive test results. From 2018 onwards, a partial 18S rRNA Hepatozoon gene fragment was sequenced from cats with positive PCR results. RESULTS: Sixty-four of 931 cats (7%) tested positive for Hepatozoon species. Sex and age did not have a statistically significant impact. Sequencing was carried out for 16 samples and revealed H felis in all cases. All cats with positive test results and a relevant travel history had been imported from the Mediterranean or south-eastern Europe. There were no autochthonous infections with Hepatozoon species. Leukocytosis, haemoconcentration and anaemia were the most common haematological abnormalities. CONCLUSIONS AND RELEVANCE: Although infections with Hepatozoon species in cats are usually subclinical, it may be useful to screen cats imported from the Mediterranean and south-eastern Europe for these pathogens to prevent local transmission cycles. There was no evidence of autochthonous infections in Germany; however, further investigations regarding a possible transmission of Hepatozoon species from infected cats to blood-feeding arthropods in Germany may be of interest. To avoid potential spread of the pathogens, ectoparasite prophylaxis is advisable.

Trypanosoma cruzi and Other Vector-Borne Infections in Shelter Dogs in Two Counties of Oklahoma, United States.

Trypanosoma cruzi is an emerging zoonotic vector-borne parasite infecting dogs and other mammals in the United States. In this study we evaluated shelter dogs in one northeastern and one southeastern county in Oklahoma for prevalence of exposure to T. cruzi. Dogs were tested for antibodies against T. cruzi using the Chagas STAT PAK® assay and for T. cruzi in circulation by PCR. In addition, dogs were tested for evidence of infection with other vector-borne organisms using the SNAP® 4Dx® Plus Test and PCR. Overall, 26 of 197 (13.2%) shelter dogs had detectable antibodies against T. cruzi and 3 of 189 (1.6%) dogs were PCR positive. In addition, we found that 42 of 197 (21.3%) shelter dogs had evidence of exposure to or were infected with at least one vector-borne agent other than T. cruzi based on serology and/or PCR; 9 of 42 (21.4%) of these dogs were also positive for T. cruzi antibodies. Other infections identified in dogs included Anaplasma phagocytophilum, Anaplasma platys, Babesia sp. (Coco), Dirofilaria immitis, Ehrlichia canis, Ehrlichia chaffeensis, Ehrlichia ewingii, and Hepatozoon americanum. This study serves to boost state-wide veterinary and public health awareness of T. cruzi and other vector-borne pathogens infecting shelter dogs in Oklahoma. Results indicate the need for more comprehensive screening of shelter dogs in Oklahoma for exposure to vector-borne agents to enhance surveillance and to identify dogs in need of additional specific veterinary care.

Tularemia: a re-emerging tick-borne infectious disease.

Tularemia is a bacterial disease of humans, wild, and domestic animals. Francisella tularensis, which is a Gram-negative coccobacillus-shaped bacterium, is the causative agent of tularemia. Recently, an increase in the number of human tularemia cases has been noticed in several countries around the world. It has been reported mostly from North America, several Scandinavian countries, and certain Asian countries. The disease spreads through vectors such as mosquitoes, horseflies, deer flies, and ticks. Humans can acquire the disease through direct contact of sick animals, consumption of infected animals, drinking or direct contact of contaminated water, and inhalation of bacteria-loaded aerosols. Low infectious dose, aerosol route of infection, and its ability to induce fatal disease make it a potential agent of biological warfare. Tularemia leads to several clinical forms, such as glandular, ulceroglandular, oculoglandular, oropharyngeal, respiratory, and typhoidal forms. The disease is diagnosed through the use of culture, serology, or molecular methods. Quinolones, tetracyclines, or aminoglycosides are frequently used in the treatment of tularemia. No licensed vaccine is available in the prophylaxis of tularemia and this is need of the time and high-priority research area. This review mostly focuses on general features, importance, current status, and preventive measures of this disease.

Bats are key hosts in the radiation of mammal-associated Bartonella bacteria.

Bats are notorious reservoirs of several zoonotic diseases and may be uniquely tolerant of infection among mammals. Broad sampling has revealed the importance of bats in the diversification and spread of viruses and eukaryotes to other animal hosts. Vector-borne bacteria of the genus Bartonella are prevalent and diverse in mammals globally and recent surveys have revealed numerous Bartonella lineages in bats. We assembled a sequence database of Bartonella strains, consisting of nine genetic loci from 209 previously characterized Bartonella lineages and 121 new cultured isolates from bats, and used these data to perform a comprehensive phylogenetic analysis of the Bartonella genus. This analysis included estimation of divergence dates using a molecular clock and ancestral reconstruction of host associations and geography. We estimate that Bartonella began infecting mammals 62 million years ago near the Cretaceous-Paleogene boundary. Additionally, the radiation of particular Bartonella clades correlate strongly to the timing of diversification and biogeography of mammalian hosts. Bats were inferred to be the ancestral hosts of all mammal-associated Bartonella and appear to be responsible for the early geographic expansion of the genus. We conclude that bats have had a deep influence on the evolutionary radiation of Bartonella bacteria and their spread to other mammalian orders. These results support a 'bat seeding' hypothesis that could explain similar evolutionary patterns in other mammalian parasite taxa. Application of such phylogenetic tools as we have used to other taxa may reveal the general importance of bats in the ancient diversification of mammalian parasites.

Crimean-Congo Hemorrhagic Fever Virus Past Infections Are Associated with Two Innate Immune Response Candidate Genes in Dromedaries.

Dromedaries are an important livestock, used as beasts of burden and for meat and milk production. However, they can act as an intermediate source or vector for transmitting zoonotic viruses to humans, such as the Middle East respiratory syndrome coronavirus (MERS-CoV) or Crimean-Congo hemorrhagic fever virus (CCHFV). After several outbreaks of CCHFV in the Arabian Peninsula, recent studies have demonstrated that CCHFV is endemic in dromedaries and camel ticks in the United Arab Emirates (UAE). There is no apparent disease in dromedaries after the bite of infected ticks; in contrast, fever, myalgia, lymphadenopathy, and petechial hemorrhaging are common symptoms in humans, with a case fatality ratio of up to 40%. We used the in-solution hybridization capture of 100 annotated immune genes to genotype 121 dromedaries from the UAE tested for seropositivity to CCHFV. Through univariate linear regression analysis, we identified two candidate genes belonging to the innate immune system: FCAR and CLEC2B. These genes have important functions in the host defense against viral infections and in stimulating natural killer cells, respectively. This study opens doors for future research into immune defense mechanisms in an enzootic host against an important zoonotic disease.

Borrelia burgdorferi sensu lato in Ixodes longiscutatus ticks from Brazilian Pampa.

Borrelia burgdorferi sensu lato (s.l.) complex includes the agents of Lyme disease/borreliosis in North America, Europe, and Asia, such Borrelia burgdorferi sensu stricto, Borrelia afzelii, Borrelia garinii, Borrelia bavariensis, Borrelia spielmanii, Borrelia bissettiae, and Borrelia mayonii. In 2013 B. burgdorferi s.l. was reported for the first time in the Neotropical region, from Ixodes aragaoi ticks in Uruguayan Pampa. In addition, from 2011 to 2016, 17 suspected human cases of borreliosis-like syndrome were reported in Rio Grande do Sul (RS) state, Brazil, which contains only part of country in the Pampa biome. The goal of this work is to report the results of a state surveillance program conducted in order to investigate the presence of B. burgdorferi s.l. in its classic vector, Ixodes spp. ticks, from the Brazilian Pampa. For this, we searched for Ixodes spp. ticks in 307 rodents from 11 municipalities of RS state. We then tested the ticks for the presence of B. burgdorferi s.l. DNA using PCR analysis. Of 35 Ixodes spp. ticks tested, one larva and one nymph of Ixodes longiscutatus ticks tested positive for Borrelia sp. DNA. The phylogenetic analysis of the flaB fragment grouped our samples (referred as Borrelia sp. haplotype Pampa) into B. burgdorferi s.l. group in a particular branch with other South American haplotypes, and this group was close to Borrelia carolinensis, B. bissettiae, and Borrelia californiensis. This is the first evidence of B. burgdorferi s.l. circulation in ticks of the genus Ixodes in Brazil. These results highlight the need for the implementation of public health policies for the diagnosis and prevention of potential cases of human borreliosis in Brazil. Further studies are needed to fill the gaps in our knowledge of the distribution, pathogenicity, reservoirs, and vectors of these emerging South American B. burgdorferi s.l. haplotypes.

Zoonotic and Vector-Borne Infections Among Urban Homeless and Marginalized People in the United States and Europe, 1990-2014.

INTRODUCTION: In high-income countries, homeless individuals in urban areas often live in crowded conditions with limited sanitation and personal hygiene. The environment of homelessness in high-income countries may result in intensified exposure to ectoparasites and urban wildlife, which can transmit infections. To date, there have been no systematic evaluations of the published literature to assess vector-borne and zoonotic disease risk to these populations. OBJECTIVES: The primary objectives of this study were to identify diversity, prevalence, and risk factors for vector-borne and zoonotic infections among people experiencing homelessness and extreme poverty in urban areas of high-income countries. METHODS: We conducted a systematic review and narrative synthesis of published epidemiologic studies of zoonotic and vector-borne infections among urban homeless and very poor people in the United States and Europe from 1990 to 2014. RESULTS: Thirty-one observational studies and 14 case studies were identified (n = 45). Seroprevalence to the human louse-borne pathogen Bartonella quintana (seroprevalence range: 0-37.5%) was identified most frequently, with clinical disease specifically observed among HIV-positive individuals. Seropositivity to Bartonella henselae (range: 0-10.3%) and Rickettsia akari (range: 0-16.2%) was noted in multiple studies. Serological evidence of exposure to Rickettsia typhi, Rickettsia prowazekii, Bartonella elizabethae, West Nile virus, Borellia recurrentis, lymphocytic choriomeningitis virus, Wohlfartiimonas chitiniclastica, Seoul hantavirus (SEOV), and Leptospira species was also identified in published studies, with SEOV associated with chronic renal disease later in life. HIV infection, injection drug use, and heavy drinking were noted across multiple studies as risk factors for infection with vector-borne and zoonotic pathogens. CONCLUSIONS: B. quintana was the most frequently reported vector-borne infection identified in our article. Delousing efforts and active surveillance among HIV-positive individuals, who are at elevated risk of complication from B. quintana infection, are advised to reduce morbidity. Given documented exposure to rodent-borne zoonoses among urban homeless and marginalized people, reducing human contact with rodents remains an important public health priority.

A case of canine borreliosis in Iran caused by Borrelia persica.

Tick-borne relapsing fever is an endemic disease in Iran, with most cases attributed to infection by Borrelia persica, which is transmitted by Ornithodoros tholozani soft ticks. Here, we report spirochetemia in blood of a puppy residing in Tehran, Iran. The causative species was identified by use of highly discriminative IGS sequencing; the 489 bp IGS sequence obtained in our study showed 99% identity (100% coverage) when compared with B. persica sequences derived from clinical cases or from O. tholozani ticks. Our IGS sequence also showed 99% similarity over 414 bp (85% coverage) with a strain from a domestic dog, and 96% over 328 bp (69% coverage) with a strain from a domestic cat. Pet-keeping in cosmopolitan cities like Tehran has become increasingly popular in recent years. Animals are often transported into the city in cages or cardboard boxes that might also harbor minute tick larvae and/or early stages of the nymphs bringing them into the urban environment. This may pose a threat to household members who buy and keep these puppies and as a result may come into close contact with infected ticks.

Virus isolation, genetic characterization and seroprevalence of Toscana virus in Algeria.

Toscana virus (TOSV; Bunyaviridae, Phlebovirus) is transmitted by sandflies of the genus Phlebotomus in the Mediterranean area. One strain of TOSV was isolated from a total of almost 23 000 sandflies collected in Kabylia, Algeria. The complete genome was sequenced, and phylogenetic studies indicated that it was most closely related with TOSV strain from Tunisia within lineage A, which also includes Italian, French and Turkish strains. A seroprevalence study performed on 370 sera collected from people living in the same area showed that almost 50% possessed neutralizing antibodies against TOSV, a rate much higher than that observed in Southern Europe. Sandfly species distribution in the study area suggests that the vector of TOSV in this region belongs to the subgenus Larroussius. These data support the rapid implementation of the diagnosis of TOSV in clinical microbiology laboratories to estimate the burden in patients presenting with neuroinvasive infections and febrile illness.