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1.
BMC Infect Dis ; 21(1): 193, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33602136

RESUMO

BACKGROUND: Scrub typhus is a largely ignored tropical disease and a leading cause of undifferentiated febrile illness in the areas of tsutsugamushi triangle caused by Orientia tsutsugamushi. It is frequently diagnosed in South Asian countries, although clear epidemiological information is not available from Nepal. After the 2015 earthquake in Nepal, a sudden upsurge in scrub typhus cases was reported. The objective of this study was to investigate epidemiology of scrub typhus and its causative agents in humans, animals, and chigger mites to understand the ongoing transmission ecology. METHODS: Scrub typhus cases with confirmed diagnosis throughout the country were included in the analysis. Studies were concentrated in the Chitwan district, the site of a major outbreak in 2016. Additional nation-wide data from 2015 to 2017 available from the government database included to analyse the disease distribution by geographical mapping. RESULTS: From 2015 to 2017, 1239 scrub typhus cases were confirmed with the largest outbreak occurring in 2016 with 831 (67.1%) cases. The case fatality rate was 5.7% in 2015 which declined to 1.1% in 2017. A nationwide outbreak of scrub typhus was declared as the cases were detected in 52 out of the 75 districts of Nepal. Seasonal trend was observed with a peak during August and September. In addition to the human cases, the presence of O. tsutsugamushi was also confirmed in animals (rodents) and chigger mites (Leptotrombidium imphalum) from the outbreak areas of southern Nepal. CONCLUSION: The detection of O. tsutsugamushi in humans, animals, and chigger mites from outbreak locations and wide-spread reports of scrub typhus throughout the country consecutively for 3 years confirms the ongoing transmission of O. tsutsugamushi with a firmly established ecology in Nepal. The country's health system needs to be strengthened for systematic surveillance, early outbreak detection, and immediate actions including treatment and preventive measures.


Assuntos
Surtos de Doenças/estatística & dados numéricos , Tifo por Ácaros/epidemiologia , Tifo por Ácaros/transmissão , Animais , Feminino , Mapeamento Geográfico , Humanos , Masculino , Nepal/epidemiologia , Orientia tsutsugamushi/isolamento & purificação , Roedores/microbiologia , Tifo por Ácaros/diagnóstico , Estações do Ano , Trombiculidae/microbiologia
2.
Emerg Infect Dis ; 24(2): 361-365, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29350148

RESUMO

Investigation of a scrub typhus outbreak in Thailand during September 2013 found that 9.1% of Thai soldiers and 11.1% of residents living in areas surrounding training sites had antibodies against the causative agent, Orientia tsutsugamushi. Sequence analysis of O. tsutsugamushi from rodents and chiggers identified 7 genogroups and 3 genotypes.


Assuntos
Surtos de Doenças , Orientia tsutsugamushi/imunologia , Tifo por Ácaros/epidemiologia , Anticorpos Antibacterianos , Humanos , Militares , Infestações por Ácaros/epidemiologia , Tailândia/epidemiologia
3.
Korean J Parasitol ; 56(5): 521-525, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30419740

RESUMO

Rodents are well-known reservoirs and vectors of many emerging and re-emerging infectious diseases, but little is known about their role in zoonotic disease transmission in Bhutan. In this study, a cross-sectional investigation of zoonotic disease pathogens in rodents was performed in Chukha district, Bhutan, where a high incidence of scrub typhus and cases of acute undifferentiated febrile illness had been reported in people during the preceding 4-6 months. Twelve rodents were trapped alive using wire-mesh traps. Following euthanasia, liver and kidney tissues were removed and tested using PCR for Orientia tsutsugamushi and other bacterial and rickettsial pathogens causing bartonellosis, borreliosis, human monocytic ehrlichiosis, human granulocytic anaplasmosis, leptospirosis, and rickettsiosis. A phylogenetic analysis was performed on all rodent species captured and pathogens detected. Four out of the 12 rodents (33.3%) tested positive by PCR for zoonotic pathogens. Anaplasma phagocytophilum, Bartonella grahamii, and B. queenslandensis were identified for the first time in Bhutan. Leptospira interrogans was also detected for the first time from rodents in Bhutan. The findings demonstrate the presence of these zoonotic pathogens in rodents in Bhutan, which may pose a risk of disease transmission to humans.


Assuntos
Anaplasma phagocytophilum/patogenicidade , Bartonella/patogenicidade , Reservatórios de Doenças , Vetores de Doenças , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/transmissão , Leptospira interrogans/patogenicidade , Orientia tsutsugamushi/patogenicidade , Filogenia , Rickettsia/patogenicidade , Roedores/genética , Roedores/microbiologia , Zoonoses/microbiologia , Zoonoses/transmissão , Anaplasma phagocytophilum/genética , Anaplasma phagocytophilum/isolamento & purificação , Animais , Bartonella/genética , Bartonella/isolamento & purificação , Butão/epidemiologia , Estudos Transversais , Reservatórios de Doenças/microbiologia , Infecções por Bactérias Gram-Negativas/epidemiologia , Humanos , Incidência , Leptospira interrogans/genética , Leptospira interrogans/isolamento & purificação , Orientia tsutsugamushi/genética , Orientia tsutsugamushi/isolamento & purificação , Rickettsia/genética , Rickettsia/isolamento & purificação , Fatores de Tempo , Zoonoses/epidemiologia
4.
J Gen Virol ; 98(5): 1122-1131, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28555540

RESUMO

Flaviviruses comprise a large and diverse group of positive-stranded RNA viruses, including tick-, mosquito- and unknown-vector-borne flaviviruses. A novel flavivirus was detected in pools of Aedes vexans nipponii (n=1) and Aedes esoensis (n=3) collected in 2012 and 2013 near the demilitarized zone (DMZ), Republic of Korea (ROK). Phylogenetic analyses of the NS5, E gene and complete polyprotein coding sequence (CDS) showed that the novel virus fell within the Aedes-borne flaviviruses (ABFVs), with nucleotide identity ranging from 57.8-75.1 %, 46.1-74.2 % and 51.1-76.2 %, respectively. While the novel ABFV was distant from other flaviviruses within the group, it formed a clade with Ilomantsi virus (ILOV). Sequence alignments of the partial NS5 gene, full-length E gene and polyprotein CDS between the novel virus and ILOV showed approximately 76.2 % nucleotide identity and 90 % amino acid identity, respectively. The ABFV identified in Aedes mosquitoes from the ROK is a novel ABFV based on the sequence analyses and is designated as Panmunjeom flavivirus (PANFV).


Assuntos
Aedes/virologia , Flavivirus/classificação , Flavivirus/isolamento & purificação , Filogenia , Animais , República da Coreia , Análise de Sequência de DNA , Homologia de Sequência do Ácido Nucleico , Proteínas do Envelope Viral/genética , Proteínas não Estruturais Virais/genética
5.
Malar J ; 16(1): 280, 2017 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-28687086

RESUMO

BACKGROUND: Novel vector control methods that can directly target outdoor malaria transmission are urgently needed in the Greater Mekong Subregion (GMS) to accelerate malaria elimination and artemisinin resistance containment efforts. Ivermectin mass drug administration (MDA) to humans has been shown to effectively kill wild Anopheles and suppress malaria transmission in West Africa. Preliminary laboratory investigations were performed to determine ivermectin susceptibility and sporontocidal effect in GMS Anopheles malaria vectors coupled with pharmacokinetic models of ivermectin at escalating doses. METHODS: A population-based pharmacokinetic model of ivermectin was developed using pre-existing data from a clinical trial conducted in Thai volunteers at the 200 µg/kg dose. To assess ivermectin susceptibility, various concentrations of ivermectin compound were mixed in human blood meals and blood-fed to Anopheles dirus, Anopheles minimus, Anopheles sawadwongporni, and Anopheles campestris. Mosquito survival was monitored daily for 7 days and a non-linear mixed effects model with probit analyses was used to calculate concentrations of ivermectin that killed 50% (LC50) of mosquitoes for each species. Blood samples were collected from Plasmodium vivax positive patients and offered to mosquitoes with or without ivermectin at the ivermectin LC25 or LC5 for An. dirus and An. minimus. RESULTS: The GMS Anopheles displayed a range of susceptibility to ivermectin with species listed from most to least susceptible being An. minimus (LC50 = 16.3 ng/ml) > An. campestris (LC50 = 26.4 ng/ml) = An. sawadwongporni (LC50 = 26.9 ng/ml) > An. dirus (LC50 = 55.6 ng/ml). Mosquito survivorship results, the pharmacokinetic model, and extensive safety data indicated that ivermectin 400 µg/kg is the ideal minimal dose for MDA in the GMS for malaria parasite transmission control. Ivermectin compound was sporontocidal to P. vivax in both An. dirus and An. minimus at the LC25 and LC5 concentrations. CONCLUSIONS: Ivermectin is lethal to dominant GMS Anopheles malaria vectors and inhibits sporogony of P. vivax at safe human relevant concentrations. The data suggest that ivermectin MDA has potential in the GMS as a vector and transmission blocking control tool to aid malaria elimination efforts.


Assuntos
Anopheles/efeitos dos fármacos , Antiprotozoários/farmacologia , Inseticidas/farmacologia , Ivermectina/farmacologia , Malária Vivax/prevenção & controle , Plasmodium vivax/efeitos dos fármacos , Animais , Sudeste Asiático , Relação Dose-Resposta a Droga , Feminino , Modelos Teóricos , Mosquitos Vetores/efeitos dos fármacos , Especificidade da Espécie
6.
J Am Mosq Control Assoc ; 33(3): 175-183, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28854115

RESUMO

Successful mating by male mosquitoes is dependent on several factors, with sugar feeding being particularly important. The effect of ingested vitamins on adult male mosquitoes is poorly understood. This laboratory study used 3 anopheline species, Anopheles campestris, An. dirus, and An. sawadwongporni, to study the effect of sugar and vitamins on male longevity, copulation, and fecundity. Males were fed 1 of 5 diets containing different combinations of sugar and vitamins: 10% glucose, 10% sucrose, 10% multivitamin syrup, 10% multivitamin syrup + 10% glucose, and 10% multivitamin syrup + 10% sucrose. The longevity of males was measured for a period of 15 days. Forced mating was used to simulate copulation, and fecundity was measured by counting the number of eggs oviposited and the hatch rate of larvae. The longevity of An. campestris and An. dirus was greatest when fed a diet of 10% multivitamin syrup + 10% glucose, and the longevity of An. sawadwongporni was greatest when fed a diet of 10% multivitamin syrup + 10% sucrose. The 1st mating routinely produced the most viable eggs when males were mated with several females. The diet of 10% multivitamin syrup + 10% sucrose produced numerically greater egg production and larval emergence for all 3 species, although this was not always statistically significant due to variability and small sample size. These results indicate that the addition of multivitamin syrup to sucrose may produce healthier and more fit male anophelines. This has potential implications for increasing insectary operations and improving the fitness of laboratory-reared male mosquitoes that will be released for mosquito and disease-pathogen control studies.


Assuntos
Anopheles/fisiologia , Longevidade/efeitos dos fármacos , Comportamento Sexual Animal/efeitos dos fármacos , Açúcares/metabolismo , Vitaminas/metabolismo , Ração Animal/análise , Animais , Anopheles/efeitos dos fármacos , Copulação , Dieta , Fertilidade/efeitos dos fármacos , Masculino
7.
J Infect Dis ; 214(5): 762-71, 2016 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-27296848

RESUMO

BACKGROUND: Three full doses of RTS,S/AS01 malaria vaccine provides partial protection against controlled human malaria parasite infection (CHMI) and natural exposure. Immunization regimens, including a delayed fractional third dose, were assessed for potential increased protection against malaria and immunologic responses. METHODS: In a phase 2a, controlled, open-label, study of healthy malaria-naive adults, 16 subjects vaccinated with a 0-, 1-, and 2-month full-dose regimen (012M) and 30 subjects who received a 0-, 1-, and 7-month regimen, including a fractional third dose (Fx017M), underwent CHMI 3 weeks after the last dose. Plasmablast heavy and light chain immunoglobulin messenger RNA sequencing and antibody avidity were evaluated. Protection against repeat CHMI was evaluated after 8 months. RESULTS: A total of 26 of 30 subjects in the Fx017M group (vaccine efficacy [VE], 86.7% [95% confidence interval [CI], 66.8%-94.6%]; P < .0001) and 10 of 16 in the 012M group (VE, 62.5% [95% CI, 29.4%-80.1%]; P = .0009) were protected against infection, and protection differed between schedules (P = .040, by the log rank test). The fractional dose boosting increased antibody somatic hypermutation and avidity and sustained high protection upon rechallenge. DISCUSSIONS: A delayed third fractional vaccine dose improved immunogenicity and protection against infection. Optimization of the RTS,S/AS01 immunization regimen may lead to improved approaches against malaria. CLINICAL TRIALS REGISTRATION: NCT01857869.


Assuntos
Esquemas de Imunização , Vacinas Antimaláricas/administração & dosagem , Vacinas Antimaláricas/imunologia , Malária/prevenção & controle , Vacinas Sintéticas/administração & dosagem , Vacinas Sintéticas/imunologia , Adolescente , Adulto , Anticorpos Antiprotozoários/biossíntese , Anticorpos Antiprotozoários/imunologia , Afinidade de Anticorpos , Feminino , Humanos , Cadeias Pesadas de Imunoglobulinas/biossíntese , Cadeias Leves de Imunoglobulina/biossíntese , Masculino , Pessoa de Meia-Idade , Adulto Jovem
8.
J Am Mosq Control Assoc ; 31(2): 149-54, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26181690

RESUMO

Animal models are often used to study hematophagous insect feeding behavior and evaluate products such as topical repellents. However, when these models are used the study animals often experience significant drops in core body temperature because of the effects of anesthesia. This study used a guinea pig model to investigate whether maintaining a normothermic core body temperature during anesthesia influenced the rate of Anopheles stephensi and Phlebotomus papatasi blood feeding. Experiments were conducted with anesthetized animals that had their body temperatures either maintained with a warming device or were allowed to drop naturally. Results showed that when guinea pigs were actively warmed by a heating device, An. stephensi feeding behavior was similar at the beginning and end of anesthesia. However, when a warming device was not used, fewer An. stephensi took a blood meal after the animals' temperatures had dropped. Phlebotomus papatasi were not as sensitive to changes in temperature and feeding rates were similar whether a warming device was used or not. These results are discussed and it is recommended that warming devices are used when conducting feeding experiments with insects sensitive to changes in host body temperature, such as An. stephensi.


Assuntos
Anestesia Geral , Anopheles/fisiologia , Temperatura Corporal , Comportamento Alimentar/fisiologia , Temperatura Alta , Phlebotomus/fisiologia , Animais , Cobaias
9.
J Infect Dis ; 209 Suppl 2: S71-8, 2014 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-24872400

RESUMO

Recent efforts to combat the growing global threat of dengue disease, including deployment of phase IIb vaccine trials, has continued to be hindered by uncertainty surrounding equitable immune responses of serotypes, relative viral fitness of vaccine vs naturally occurring strains, and the importance of altered immune environments due to natural delivery routes. Human infection models can significantly improve our understanding of the importance of certain phenotypic characteristics of viral strains, and inform strain selection and trial design. With human models, we can further assess the importance of the natural delivery route of DENV and/or the accompanying mosquito salivary milieu. Accordingly, we discuss the use of mosquitoes in such a human infection model with DENV, identify important considerations, and make preliminary recommendations for deployment of such a mosquito improved DENV human infection model (miDHIM).


Assuntos
Aedes/virologia , Dengue/prevenção & controle , Modelos Biológicos , Animais , Dengue/tratamento farmacológico , Vacinas contra Dengue/imunologia , Vírus da Dengue , Modelos Animais de Doenças , Humanos
10.
J Med Entomol ; 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38912641

RESUMO

Factory-treated permethrin uniforms are the primary method used by the US Army to prevent arthropod bites and transmission of arthropod-borne diseases. In this study previously worn uniforms were collected from cadets at the United States Military Academy in West Point, NY to determine the amount of permethrin remaining after prolonged wear and subsequent effects on ticks. Six trousers were collected from cadets in the sophomore, junior, and senior classes. A new, unwashed uniform served as a positive control and an untreated maternity uniform served as a negative control. Fabric samples were removed from each trouser and used in bioassays with laboratory-reared Ixodes scapularis Say nymphs. Contact irritancy bioassays measured the nymphs' ability to remain in contact with fabric for a period of 5 min. Toxicity bioassays measured tick survival at 1 and 24 h after contacting uniform samples. liquid chromatography-mass spectrometry was used to quantify the permethrin content (mg/cm2) in each uniform after the bioassays were complete. The results showed significant amounts of permethrin were lost after extended wear and it was related to the cadet year group. The contact irritancy assays found uniforms with less permethrin did not irritate ticks and cause them to dislodge. Mortality was also affected by permethrin levels, with less ticks dying at 24 h on older uniforms. The results from this study show older uniforms lose most of their permethrin and no longer provide the same levels of protection.

11.
Mil Med ; 2022 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-35587397

RESUMO

INTRODUCTION: The Army uses permethrin-treated uniforms as the primary method to protect soldiers from tick-borne diseases. Permethrin binds strongly to fabric and provides long-term protection against many blood-feeding arthropods. However, protection decreases if the uniforms are not washed and cared for according to label instructions. This study was conducted among cadets at the United States Military Academy (USMA) at West Point, NY, to determine what the cadets know about permethrin and how they care for and wear their uniforms. West Point is in an area with high rates of tick-borne disease transmission. A survey was developed to determine what cadets know about the threat of tick-borne diseases and if they wear and maintain their uniforms in a manner that effectively maintains permethrin levels. MATERIALS AND METHODS: A 16-question survey was developed and submitted to the local review board for approval. The study was classified as human subjects research according to 32CFR219 and met the requirements for exempt status under 32CFR219.104(d)(2)(i). After receiving approval, a hard copy survey was distributed among cadets with efforts to sample at least 50 members from each cadet class. RESULTS: A total of 319 cadets provided responses to the survey questions, representing more than 7% of the cadet population at the USMA. The results showed most cadets knew their uniforms were treated with permethrin, but less than half knew there are specific instructions attached to their uniforms describing how the uniforms should be laundered. From the cadets who knew there were instructions, most admittedly did not follow the instructions. Sixteen percent of cadets said they had dry-cleaned their uniforms. This is a process known to remove most of the permethrin. The majority of cadets viewed the risk of tick-borne disease at West Point to be moderate or lower. CONCLUSIONS: This study provides a basic understanding of the wear patterns of permethrin-treated uniforms among cadets at the USMA. It is also one of the few studies to measure knowledge and uniform-wearing behavior among service members since the Army switched to factory-treated uniforms in 2013. The results indicate that compliance with uniform laundry and care instructions is low. This information is useful to develop training plans and educate cadets how they can wear and take care of their permethrin-treated uniforms to better protect themselves from tick-borne diseases.

12.
Ticks Tick Borne Dis ; 13(1): 101845, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34689003

RESUMO

The livestock industry in Mongolia accounts for 24% of national revenue, with one third of the population maintaining a pastoral lifestyle. This close connection between Mongolian population and livestock is a major concern for pathogen transfer, especially given the increase in vector-borne diseases globally. This study examines blood samples from livestock to assess the prevalence of tick-borne bacterial infections across three provinces in Mongolia (Dornogovi, Selenge, Töv). Whole blood samples from 243 livestock (cattle=38, camel=11, goat=85, horse=22, sheep=87) were analyzed with 16S metagenomics next-generation sequencing (NGS) to screen for bacterial pathogens. Positive-NGS samples for Anaplasma, Bartonella, Ehrlichia, Francisella, Leptospira, and Rickettsia were confirmed by conventional PCR and DNA sequencing. Prevalence rates of Anaplasma, Bartonella, and Ehrlichia were 57.6%, 12.8%, and 0.4%, respectively. A significant difference in the prevalence of Anaplasma spp. in livestock by province was observed, with a higher prevalence in Selenge (74.2%, p<0.001) and Töv (64.2% p = 0.006) compared to the semi-arid region of Dornogovi (39.8%). In contrast, no association was observed in Bartonella prevalence by provinces. All Anaplasma sequences (N = 139) were characterized as A. ovis. For Bartonella species characterization, phylogenetic analyses of gltA and rpoB genes identified three Bartonella species including B. bovis, B. melophagi and Candidatus B. ovis. Bartonella bovis was detected in all 22-positive cattle, while B. melophagi and Candidatus B. ovis were found in four and three sheep, respectively. This study identifies a high prevalence of tick-borne pathogens within the livestock population and to our knowledge, is the first time NGS methods have been used to explore tick-borne diseases in Mongolia. Further research is needed in Mongolia to better understand the clinical and economic burdens associated with tick-borne diseases in both livestock and pastoral herder populations.


Assuntos
Gado , Doenças Transmitidas por Carrapatos , Anaplasma/genética , Animais , Bovinos , Sequenciamento de Nucleotídeos em Larga Escala , Cavalos , Gado/microbiologia , Filogenia , Ovinos , Doenças Transmitidas por Carrapatos/epidemiologia , Doenças Transmitidas por Carrapatos/microbiologia , Doenças Transmitidas por Carrapatos/veterinária
13.
J Med Entomol ; 59(3): 1047-1052, 2022 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-35043209

RESUMO

There are eight Anopheles spp. present in the Republic of Korea (ROK), including five members of the Anopheles Hyrcanus Group that cannot be identified using current morphological methods. The vector competence of only Anopheles sinensis s.s., An. lesteri, and An. kleini have been investigated. As the geographical distribution of Anopheles spp. varies in the ROK, determining the relative vector competence of the Anopheles spp. provides a basis for delineating malaria risks to Korean populations and U.S. military/civilian populations deployed to the ROK. Anopheles belenrae and An. pullus, collected from a malaria high-risk area in the ROK, were evaluated for vector competence of P. vivax. A total of 1,000 each of An. dirus (Thai strain), and Korean strains of An. pullus and An. belenrae were fed on P. vivax infected blood collected from Thai patients via artificial membrane feeding. The overall oocyst infection rates for An. dirus, An. pullus, and An. belenrae dissected on days 8-9 postfeed were 64.1, 12.0, and 11.6%, respectively. The overall sporozoite infection rates for those species dissected on days 14-15 postfeed were 84.5, 3.4, and 5.1% respectively. The salivary gland sporozoite indices for positive females with +4 (>1,000 sporozoites) were observed in An. dirus (72.8%), but not observed for either An. pullus or An. belenrae. Most sporozoite-positive An. pullus (83.3%) and An. belenrae (71.4%) females were observed with only +1 (1-10 sporozoites) salivary glands. These data indicate that both An. belenrae and An. pullus are very poor vectors of P. vivax.


Assuntos
Anopheles , Malária Vivax , Animais , Feminino , Humanos , Masculino , Mosquitos Vetores , Plasmodium vivax , Esporozoítos , Tailândia
14.
Front Microbiol ; 13: 946631, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36033893

RESUMO

Tick-borne diseases are a major public health concern in Mongolia. Nomadic pastoralists, which make up ~ 26% of Mongolia's population, are at an increased risk of both tick bite exposure and economic loss associated with clinical disease in herds. This study sought to further characterize tick-borne pathogens present in Dermacentor ticks (n = 1,773) sampled in 2019 from 15 of Mongolia's 21 aimags (provinces). The ticks were morphologically identified and sorted into 377 pools which were then screened using Next-Generation Sequencing paired with confirmatory PCR and DNA sequence analysis. Rickettsia spp. were detected in 88.33% of pools, while Anaplasma spp. and Bartonella spp. were detected in 3.18 and 0.79% of pools, respectively. Khentii had the highest infection rate for Rickettsia spp. (76.61%; CI: 34.65-94.79%), while Arkhangai had the highest infection rate for Anaplasma spp. (7.79%; CI:4.04-13.72%). The exclusive detection of Anaplasma spp. in tick pools collected from livestock supports previous work in this area that suggests livestock play a significant role in disease maintenance. The detection of Anaplasma, Bartonella, and Rickettsia demonstrates a heightened risk for infection throughout Mongolia, with this study, to our knowledge, documenting the first detection of Bartonella melophagi in ticks collected in Mongolia. Further research deploying NGS methods is needed to characterize tick-borne pathogens in other endemic tick species found in Mongolia, including Hyalomma asiaticum and Ixodes persulcatus.

15.
J Med Entomol ; 58(3): 1331-1344, 2021 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-33367702

RESUMO

Borrelia is a genus of spirochetal bacteria with several species known to cause disease in humans. The distribution of Borrelia has rarely been studied in Thailand. In this study, a retrospective survey of Borrelia was conducted in ticks and wild rodents to better characterize the prevalence, diversity, and distribution of Borrelia across Thailand. Several pools of DNA from tick samples were positive for Borrelia spp. (36/258, 13.9%). Borrelia theileri/B. lonestari was found in 17 tick samples (16 pools of Haemaphysalis bandicota and 1 pool of Rhipicephalus sp.), and Borrelia yangtzensis was found in 8 tick samples (2 pools of H. bandicota and 6 pools of Ixodes granulatus). Borrelia spp. were detected at low prevalence levels in rodent tissue samples (24/2001, 1.2%), with 19 identified as B. theileri or B. lonestari and 5 identified as B. miyamotoi. Several geographic and species-specific infection trends were apparent, with Ixodes ticks infected with B. yangtzensis and Haemaphysalis and Rhipicephalus ticks infected with both B. yangtzensis and B. theileri/B. lonestari. Notably, B. yangtzensis showed a similar geographic distribution to B. miyamotoi, which was identified in new areas of Thailand in this study. The flagellin gene sequence from B. miyamotoi was more similar to European (99.3-99.9%) than Japanese (96.9-97.6%) genotypes. This study greatly expands the knowledge of Borrelia in Thailand and identified several Borrelia species for the first time. It also found several ticks and rodents infected with the pathogen that were not previously known to carry Borrelia.


Assuntos
Infecções por Borrelia/veterinária , Borrelia/isolamento & purificação , Ixodidae/microbiologia , Doenças dos Roedores/epidemiologia , Roedores , Animais , Infecções por Borrelia/epidemiologia , Infecções por Borrelia/microbiologia , Feminino , Ixodidae/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/microbiologia , Masculino , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Estudos Retrospectivos , Doenças dos Roedores/microbiologia , Tailândia/epidemiologia
16.
Acta Trop ; 220: 105953, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33979638

RESUMO

Several light trap devices have been invented and developed to assess the abundance of sand flies. Traps available in the market have different designs and attractant combinations to catch sand fly vectors. We evaluated the efficacy of four commercial light traps and determined the effect of trap placement and carbon dioxide (CO2) on sand fly collection in northern Thailand. Trap evaluations were conducted at two natural caves located in Chiang Rai province, Thailand. In the first part of the study, the efficacies of four trap types including the Centers for Disease Control miniature light trap (CDC LT), Encephalitis Vector Survey trap (EVS), CDC Updraft Blacklight trap (CDC UB), and Laika trap (LK) were evaluated and compared using a Latin square experimental design. The second half of the study evaluated the influence of trap placement and CO2 on sand fly collection. Additionally, CDC LT were placed inside, outside, and at the entrance of caves to compare the number of sand flies collected. For the trap efficacy experiment, a total of 11,876 phlebotomine sand flies were collected over 32 trap-nights. Results demonstrated that CDC LT, CDC UB, and LK collected significantly more sand flies than EVS (P > 0.05). However, there were no significant differences between the numbers of sand flies collected by CDC LT, CDC UB, and LK. A total of 6,698 sand flies were collected from the trap placement and CO2 experiment over 72 trap-nights. Results showed that CO2 did not influence the numbers of sand flies captured (P < 0.05), whereas trap placement at the entrance of the caves resulted in collection of significantly more sand flies than traps placed inside and outside of the caves. We found the CDC LT, CDC UB, and LK without CO2 captured the greatest amount of sand flies. This was particularly observed when traps were placed at the entrance of a cave, perhaps because of the greater passage of stimuli caused by wind flow at the entrance of the cave. The light traps in this study can be used effectively to collect sand fly vectors in northern Thailand.


Assuntos
Dióxido de Carbono , Controle de Insetos/métodos , Phlebotomus , Psychodidae , Animais , Cavernas , Vetores de Doenças , Controle de Insetos/instrumentação , Tailândia
17.
Travel Med Infect Dis ; 42: 102086, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34044127

RESUMO

BACKGROUND: Scrub typhus is an important disease in the Asia-Pacific countries with increasing relevance for public health worldwide. Entomological risk assessment for scrub typhus and rickettsial disease in Phu Chi Fah village-Chiang Rai was performed to determine areas at greatest risk for disease transmission in order to increase awareness of diseases to travelers and healthcare workers. METHODS: From 2016 to 2018, rodents and chiggers were collected from 7 sites covering residential, grassland, and forest areas to determine the prevalence of pathogen of interest. The correlation between land type and vector-host-pathogen interaction system was investigated. RESULT: High prevalence of O. tsutsugamushi-infected and Rickettsia-infected chiggers was observed especially in areas with grassland and forest ecotones. Chigger and rodent species composition were negatively associated with the level of human disturbance. Increased density of rodents was responsible for a higher abundance of chigger population and increased prevalence of O. tsutsugmaushi infection in chigger in the following year. CONCLUSION: Communities in the study areas have an increased exposure risk to scrub typhus and potentially spotted fever group rickettsiosis. Travellers to this endemic area should pay more attention pathogen risks so as to avoid vector and disease exposure. Seasonal rodenticidal activity may help migitate the risk of pathogen transmission.


Assuntos
Orientia tsutsugamushi , Infecções por Rickettsia , Tifo por Ácaros , Trombiculidae , Animais , Infecções por Rickettsia/epidemiologia , Tifo por Ácaros/epidemiologia , Tailândia/epidemiologia
18.
Parasit Vectors ; 14(1): 378, 2021 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-34315509

RESUMO

BACKGROUND: Ivermectin mass drug administration (MDA) could accelerate malaria elimination in the Greater Mekong Subregion. This study was performed to characterize the bionomics of Anopheles in Surat Thani province, Thailand. METHODS: Mosquitoes were collected via human landing collections between February and October 2019. Anopheles mosquitoes were morphologically identified to species. Primary Anopheles malaria vectors were dissected to assess parity status, and a subset were evaluated for molecular identification and Plasmodium detection. RESULTS: A total of 17,348 mosquitoes were collected during the study period; of these, 5777 were Anopheles mosquitoes. Morphological studies identified 15 Anopheles species, of which the most abundant were Anopheles minimus (s.l.) (87.16%, n = 5035), An. dirus s.l. (7.05%, n = 407) and An. barbirostris s.l. (2.86%, n = 165). Molecular identification confirmed that of the An. minimus s.l. mosquitoes collected, 99.80% were An. minimus (s.s.) (n = 484) and 0.2% were An. aconitus (n = 1), of the An. dirus (s.l.) collected, 100% were An. baimaii (n = 348), and of the An. maculatus (s.l.) collected, 93.62% were An. maculatus (s.s.) (n = 44) and 6.38% were An. sawadwongporni (n = 3). No Anopheles mosquito tested was Plasmodium positive (0/879). An average of 11.46 Anopheles were captured per collector per night. There were differences between species in hour of collection (Kruskal-Wallis H-test: χ2 = 80.89, P < 0.0001, n = 5666), with more An. barbirostris (s.l.) and An. maculatus (s.l.) caught earlier compared to An. minimus (s.l.) (P = 0.0001 and P < 0.0001, respectively) and An. dirus (s.l.) (P = 0.0082 and P < 0.001, respectively). The proportion of parous An. minimus (s.l.) captured by hour increased throughout the night (Wald Chi-square: χ2 = 17.31, P = 0.000, odds ratio = 1.0535, 95% confidence interval 1.0279-1.0796, n = 3400). Overall, An. minimus (s.l.) parity was 67.68% (2375/3509) with an intra-cluster correlation of 0.0378. A power calculation determined that an An. minimus (s.l.) parity reduction treatment effect size = 34%, with four clusters per treatment arm and a minimum of 300 mosquitoes dissected per cluster, at an α = 0.05, will provide 82% power to detect a significant difference following ivermectin MDA. CONCLUSIONS: The study area in Surat Thani province is an ideal location to evaluate the impact of ivermectin MDA on An. minimus parity.


Assuntos
Anopheles/fisiologia , Doenças Endêmicas , Malária/transmissão , Mosquitos Vetores/fisiologia , Animais , Anopheles/classificação , Anopheles/genética , Anopheles/parasitologia , Análise por Conglomerados , Humanos , Malária/epidemiologia , Mosquitos Vetores/classificação , Mosquitos Vetores/genética , Mosquitos Vetores/parasitologia , Plasmodium/classificação , Plasmodium/genética , Plasmodium/isolamento & purificação , Reação em Cadeia da Polimerase , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de DNA , Tailândia/epidemiologia , Fatores de Tempo
19.
Pathogens ; 9(6)2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32512828

RESUMO

Entomological surveillance for arthropod-borne viruses is vital for monitoring vector-borne diseases and informing vector control programs. In this study, we conducted entomological surveillance in Zika virus endemic areas. In Thailand, it is standard protocol to perform mosquito control within 24 h of a reported dengue case. Aedes females were collected within 72 h of case reports from villages with recent Zika-human cases in Kamphaeng Phet Province, Thailand in 2017 and 2018. Mosquitoes were bisected into head-thorax and abdomen and then screened for Zika (ZIKV) and dengue (DENV) viruses using real-time RT-PCR. ZIKV RNA was detected in three samples from two female Ae. aegypti (1.4%). A partial envelope sequence analysis revealed that the ZIKV sequences were the Asian lineage identical to sequences from ZIKV-infected cases reported in Thailand during 2016 and 2017. Dengue virus-1 (DENV-1) and dengue virus-4 (DENV-4) were found in four Ae. aegypti females (2.8%), and partial capsid sequences were nearly identical with DENV-1 and DENV-4 from Thai human cases reported in 2017. Findings in the current study demonstrate the importance of entomological surveillance programs to public health mosquito-borne disease prevention measures and control.

20.
Clin Pharmacol Ther ; 107(5): 1221-1230, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31697848

RESUMO

Mass administration of antimalarial drugs and ivermectin are being considered as potential accelerators of malaria elimination. The safety, tolerability, pharmacokinetics, and mosquito-lethal effects of combinations of ivermectin, dihydroartemisinin-piperaquine, and primaquine were evaluated. Coadministration of ivermectin and dihydroartemisinin-piperaquine resulted in increased ivermectin concentrations with corresponding increases in mosquito-lethal effect across all subjects. Exposure to piperaquine was also increased when coadministered with ivermectin, but electrocardiograph QT-interval prolongation was not increased. One subject had transiently impaired liver function. Ivermectin mosquito-lethal effect was greater than predicted previously against the major Southeast Asian malaria vectors. Both Anopheles dirus and Anopheles minimus mosquito mortality was increased substantially (20-fold and 35-fold increase, respectively) when feeding on volunteer blood after ivermectin administration compared with in vitro ivermectin-spiked blood. This suggests the presence of ivermectin metabolites that impart mosquito-lethal effects. Further studies of this combined approach to accelerate malaria elimination are warranted.


Assuntos
Artemisininas/administração & dosagem , Ivermectina/administração & dosagem , Primaquina/administração & dosagem , Quinolinas/administração & dosagem , Adolescente , Adulto , Animais , Anopheles/efeitos dos fármacos , Antimaláricos/administração & dosagem , Antimaláricos/efeitos adversos , Antimaláricos/farmacocinética , Artemisininas/efeitos adversos , Artemisininas/farmacocinética , Interações Medicamentosas , Quimioterapia Combinada , Feminino , Humanos , Inseticidas/administração & dosagem , Inseticidas/efeitos adversos , Inseticidas/farmacocinética , Ivermectina/efeitos adversos , Ivermectina/farmacocinética , Malária/prevenção & controle , Masculino , Pessoa de Meia-Idade , Primaquina/efeitos adversos , Primaquina/farmacocinética , Quinolinas/efeitos adversos , Quinolinas/farmacocinética , Tailândia , Adulto Jovem
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