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1.
Clin Infect Dis ; 2021 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-33462580

RESUMO

BACKGROUND: Dengue is the most significant mosquito-borne viral disease; there are no specific therapeutics. The antiparasitic drug ivermectin efficiently inhibits the replication of all 4 dengue virus serotypes in vitro. METHODS: We conducted 2 consecutive randomized, double-blind, placebo-controlled trials in adult dengue patients to evaluate safety and virological and clinical efficacies of ivermectin. After a phase 2 trial with 2 or 3 days of 1 daily dose of 400 µg/kg ivermectin, we continued with a phase 3, placebo-controlled trial with 3 days of 400 µg/kg ivermectin. RESULTS: The phase 2 trial showed a trend in reduction of plasma nonstructural protein 1 (NS1) clearance time in the 3-day ivermectin group compared with placebo. Combining phase 2 and 3 trials, 203 patients were included in the intention to treat analysis (100 and 103 patients receiving ivermectin and placebo, respectively). Dengue hemorrhagic fever occurred in 24 (24.0%) of ivermectin-treated patients and 32 (31.1%) patients receiving placebo (P = .260). The median (95% confidence interval [CI]) clearance time of NS1 antigenemia was shorter in the ivermectin group (71.5 [95% CI 59.9-84.0] hours vs 95.8 [95% CI 83.9-120.0] hours, P = .014). At discharge, 72.0% and 47.6% of patients in the ivermectin and placebo groups, respectively had undetectable plasma NS1 (P = .001). There were no differences in the viremia clearance time and incidence of adverse events between the 2 groups. CONCLUSIONS: A 3-day 1 daily dose of 400 µg/kg oral ivermectin was safe and accelerated NS1 antigenemia clearance in dengue patients. However, clinical efficacy of ivermectin was not observed at this dosage regimen.

2.
Trop Med Infect Dis ; 5(4)2020 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-33233808

RESUMO

Leishmaniasis, a sandfly-transmitted protozoan infection, is a neglected health threat in Thailand and the information on its vector is scarce. This study aimed to identify sandfly distribution, abundance, and environmental conditions of natural breeding sites in the cave areas of Satun Province, where previous cases of leishmaniasis were reported. Sandflies were collected during a six-month period using CDC light traps and modified emergence traps. Species distribution, relative abundance, and environmental conditions of potential breeding sites were determined. Our survey of 12,790 sandflies found the highest female abundance in April-May. We identified six known species, the most prevalent being Sergentomyia anodontis. We also found S. barraudi, a potential Leishmania spp. vector, distributing in this area. Most male sandflies had partially rotated genitalia, indicating the breeding site proximity to our trap locations. Potential resting/breeding sites were discovered outside the cave during February-March, and inside during May-June. The environmental parameters showed warm climate, moderate humidity, moderately alkaline pH, moderate-to-high macronutrients, and low-to-high organic matters. In summary, our study provided the spatiotemporal distribution and environmental condition of sandfly potential breeding sites in the cave areas of Satun Province. This data may contribute to more effective vector surveillance programs in the future.

3.
Am J Trop Med Hyg ; 101(6): 1397-1401, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31595871

RESUMO

Although human infections of Plasmodium knowlesi have been found throughout Southeast Asia, most cases originated from Malaysian Borneo. In Thailand, P. knowlesi malaria was considered extremely rare. However, during October 2017-September 2018, there was a surge in the number of reported P. knowlesi cases. Here, a series of six cases of P. knowlesi malaria found during this period in Songkhla and Narathiwat provinces of southern Thailand are presented. All cases were confirmed by polymerase chain reaction. The unprecedented case number in the affected area is a warning sign of an increasing P. knowlesi burden in the south of Thailand.


Assuntos
Malária/diagnóstico , Plasmodium knowlesi/patogenicidade , Adulto , Antimaláricos/uso terapêutico , Feminino , Humanos , Malária/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Plasmodium knowlesi/efeitos dos fármacos , Tailândia , Viagem , Adulto Jovem
4.
Infect Dis Poverty ; 8(1): 72, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31420004

RESUMO

After publication of this article [1], it was brought to our attention that figure 2 did not display correctly. The correct figure 2 is as below.

5.
Infect Dis Poverty ; 8(1): 38, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31130143

RESUMO

BACKGROUND: Lymphatic filariasis is endemic in nine of the eleven Member States of the World Health Organization South East Asia Region. This article describes the intensive interventions with the National Programme for Elimination of Lymphatic Filariasis in Thailand since its launch in 2001 till the validation of its elimination in 2017. METHODS: A baseline epidemiological survey was initiated in 2001 to identify both brugian and bancroftian filarial areas and delineate its endemicity. Mass drug administration (MDA) with diethylcarbamazine citrate (DEC) and albendazole (ALB) was implemented in a total of 357 implementation units (IUs) in 11 lymphatic filariasis (LF) endemic provinces. The implementing unit (IU) was a sub-village. Stop-MDA surveys were conducted in 2006 in the 11 LF endemic provinces among population over 6 years of age and children of ≤6 years using immunochromatographic test (ICT) for Wuchereria bancrofti antigen and microfilariae (mf) detection for Brugia malayi. In Narathiwat province, Stop-MDA surveys were done in 2011 using ELISA. Transmission assessment surveys (TAS) were conducted in 2012-2013, 2015 and 2016-2017 among school students in the 6-7-year age-group. Surveillance of migrant populations through the national migrant health checkup were intensified in seven provinces over 2002-2017 for LF antigenaemia using ICT test cards. In four B. malayi endemic provinces, annual surveys to detect LF reservoir in domestic cats commenced in 1994. A 2001 survey of the chronic disease burden for LF established a register of the cumulative number of people with lymphedema/elephantiasis. RESULTS: A total of five rounds of MDA annually were implemented over 2002-2006 in all IUs. Additional annual rounds of MDA were required in 87 IUs of Narathiwat province from 2007 to 2011 due to persistent infection. The annual national drug coverage with MDA over 2002-2012 was in the range of 68.0 to 95.4%. Stop-MDA surveys in 2006 in the 11 LF endemic provinces found nine mf positive cases in seven IUs in Narathiwat province with the highest prevalence of 0.8% (range: 0.1-0.8%). In Narathiwat TAS-1, TAS-2 and TAS-3 detected below transmission threshold rates for B. malayi mf among antibody positive children (0.3, 0.2 and 0.7% respectively). Contact tracing both all mf cases in all three TAS yielded no positive cases. Through the migrant health checkup, a total of 23 477 persons were tested, showing a positive rate of 0.7% (range: 0.1-2.7%) over years 2002-2017. In Narathiwat province, annual ivermectin treatment among cats commenced in 2003 resulting in a decline of mf prevalence among cats from 8.0% in 1995 to 0.8% in 2015. As of April 2017, a total of 99 lymphoedema/elephantiasis patients were registered and followed-up under 34 health facilities. CONCLUSIONS: Thailand over the years 2002 to 2011 conducted extensive MDA with high coverage rates. Through periodic and regular monitoring surveys it delineated LF transmission areas at sub-village level and demonstrated through its evaluation surveys - the Stop-MDA surveys and TAS, below transmission threshold rates that enabled its validation of LF elimination. In September 2017, World Health Organization acknowledged the Ministry of Health Thailand had eliminated lymphatic filariasis as a public health problem.


Assuntos
Albendazol/uso terapêutico , Anti-Helmínticos/uso terapêutico , Dietilcarbamazina/uso terapêutico , Filariose Linfática/tratamento farmacológico , Filariose Linfática/prevenção & controle , Administração Massiva de Medicamentos/métodos , Adolescente , Adulto , Animais , Anticorpos Anti-Helmínticos , Antígenos de Helmintos , Doenças do Gato/parasitologia , Gatos , Criança , Pré-Escolar , Erradicação de Doenças/métodos , Reservatórios de Doenças/parasitologia , Uso de Medicamentos , Doenças Endêmicas , Feminino , Filaricidas/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade , Prática de Saúde Pública , Inquéritos e Questionários , Tailândia , Migrantes , Wuchereria bancrofti/efeitos dos fármacos , Wuchereria bancrofti/imunologia , Adulto Jovem
6.
Exp Parasitol ; 200: 92-98, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30991039

RESUMO

Adult Brugia malayi proteins with high potential as epidemiological markers, diagnostic and therapeutic targets, and/or vaccine candidates were revealed by using microfilaremic human sera and an immunoproteomic approach. They were HSP70, cytoplasmic intermediate filament protein, independent phosphoglycerate mutase, and enolase. Brugia malayi microfilaria-specific proteins that formed circulating immune complexes (ICs) were investigated. The IC-forming proteins were orthologues of hypothetical protein Bm1_12480, Pao retrotransposon peptidase family protein, uncoordinated protein 44, NAD-binding domain containing protein of the UDP-glucose/GDP-mannose dehydrogenase family which contained ankyrin repeat region, ZU5 domain with C-terminal death domain, C2 domain containing protein, and FLJ90013 protein of the eukaryotic membrane protein family. Antibodies to these proteins were not free in the microfilaremic sera, raising the possible role of the IC-forming proteins in an immune evasion mechanism of the circulating microfilariae to avoid antibody-mediated-host immunity. Moreover, detection of these ICs should be able to replace the inconvenient night blood sampling for microfilaria in an evaluation of efficacy of anti-microfilarial agents.


Assuntos
Complexo Antígeno-Anticorpo/imunologia , Antígenos de Helmintos/imunologia , Brugia Malayi/imunologia , Filariose/imunologia , Proteínas de Helminto/imunologia , Soros Imunes/imunologia , Animais , Biologia Computacional , Eletroforese em Gel Bidimensional , Eletroforese em Gel de Poliacrilamida , Filariose/sangue , Proteínas de Choque Térmico HSP70/imunologia , Humanos , Immunoblotting , Proteínas de Filamentos Intermediários/imunologia , Microfilárias/imunologia , Fosfoglicerato Mutase/imunologia , Fosfopiruvato Hidratase/imunologia , Proteômica/métodos
7.
Parasitol Res ; 118(4): 1289-1297, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30746583

RESUMO

Lymphatic filariae are important human and animal parasites. Infection by these parasites could lead to severe morbidity and has significant socioeconomic impacts. Topical selamectin is a semi-synthetic macrocyclic lactone that is widely used to prevent heartworm infection. Up until now, there were no studies that investigated the efficacy of selamectin in lymphatic filariae. Therefore, we aimed to study the chemotherapeutic and chemoprophylactic efficacies of selamectin use for cats in brugian filariasis-endemic areas in Southern Thailand. To assess chemotherapeutic efficacy of topical selamectin, eight Brugia malayi and six Brugia pahangi microfilaremic cats were treated with a single administration of topical selamectin. For chemoprophylactic efficacy assessment, a single application of topical selamectin was administrated to 9 healthy, uninfected cats. The cats in both groups were subjected to a monthly blood testing for microfilariae and filarial DNA for 1 year. Topical selamectin treatment in B. malayi and B. pahangi microfilaremic cats showed 100% effectivity in eradicating microfilaremia but only 78.5% effectivity in eliminating filarial DNA. In the chemoprophylactic group, selamectin demonstrated 66.7% efficacy in preventing B. malayi infection. Our findings suggest that a single administration of 6 mg/kg topical selamectin given every two months could effectively prevent B. malayi infection. Application of topical selamectin twice a year could block circulating microfilariae. Since there are no treatment guidelines currently available for lymphatic filarial infection in cats, the data obtained from this study could be used to guide the management of brugian lymphatic filarial infection in reservoir cats.


Assuntos
Antiparasitários/uso terapêutico , Brugia Malayi/efeitos dos fármacos , Brugia pahangi/efeitos dos fármacos , Filariose Linfática/tratamento farmacológico , Filariose Linfática/veterinária , Ivermectina/análogos & derivados , Animais , Gatos , Quimioprevenção/métodos , Filariose Linfática/parasitologia , Humanos , Ivermectina/uso terapêutico , Microfilárias/crescimento & desenvolvimento , Tailândia
8.
Vet Parasitol ; 245: 42-47, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-28969836

RESUMO

Lymphatic filariasis (LF) is one of the neglected tropical diseases which causes permanent and long term disability worldwide. LF is caused by filarial nematode parasites, i.e. Wuchereria bancrofti, Brugia malayi, and B. timori. All available antifilarial drugs currently being used have shown a limited adulticidal activity. Discoveries of endosymbiont rickettsia-like bacterium, Wolbachia in filarial nematodes provided a novel approach for antibiotic use in eradication of filarial diseases. The earlier studies revealed the macrofilaricidal efficacy of doxycycline against filarial nematodes. Chemotherapeutic efficiency of doxycycline has been studied against many filarial parasites, but there are still no therapeutic trials of the drug regimens for B. malayi treatment in naturally infected cats. Thus, this study would be the first attempt to study the efficiency of doxycycline (DOXY) alone or in combination with ivermectin (IVM) for treatment of B. malayi in naturally infected cats. A total of 26 B. malayi-infected cats in the endemic areas were recruited and divided into 3 groups, receiving different treatment regimens; a single dose of ivermectin only (IVM), doxycycline only (DOXY) and a combination of ivermectin and doxycycline (DOXY-IVM). The efficacy of each therapatic regimen was evaluated by detecting the presence of microfilaria using parasitological and molecular techniques monthly up to 2 years after starting the treatment. The IVM treated group had a significant rapid reduction of microfilariae in the first month; however, recurrence of microfilaraemia was observed in some cats. By contrast, the DOXY and DOXY-IVM groups showed a better result with a gradual decrease in microfilariae with no recurrence. These 2 groups were not only virtually deprived of infection but also sustained the sterility of infection through the course of study. These results revealed the advantages of using in B. malayi treatment in cats. Doxycycline showed to have both microfilaricidal and adulticidal effects on lymphatic filariae which maintained the long-term response to control of B. malayi infection in cats.


Assuntos
Brugia Malayi , Doenças do Gato/parasitologia , Doxiciclina/uso terapêutico , Filariose/veterinária , Ivermectina/uso terapêutico , Animais , Doenças do Gato/tratamento farmacológico , Gatos , Doxiciclina/administração & dosagem , Quimioterapia Combinada , Filariose/tratamento farmacológico , Filariose/parasitologia , Ivermectina/administração & dosagem
9.
J Med Entomol ; 54(2): 429-434, 2017 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-27744363

RESUMO

Although female sand flies are best known as the vectors of Leishmania parasites and viruses, several previous reports have demonstrated that these insects can also act as vectors for the trypanosomes of bats, lizards, and snakes. In this report, we created an inventory of Phlebotomine sand flies from southern Thailand. A novel trypanosome was found in a specimen of Phlebotomus stantoni, and two sand fly species newly recorded in the country, Sergentomyia khawi and Sergentomyia hivernus, were described. PCR primer pairs specific for the internal transcribed spacer 1 (ITS1) and the small subunit ribosomal DNA (SSU rDNA) gene of trypanosomatids were used to demonstrate the presence of the parasite in the sand fly. In addition, the Cytochrome b (CytB) gene was used to identify the sand fly species. Among the 45 samples of the sand fly that were collected, seven samples were Ph. stantoni sand flies and a single sample was positive for Trypanosoma sp. through PCR analysis. This study represents the first detection of Trypanosoma sp. in a sand fly from Thailand. The ITS1 and SSU rDNA sequences indicated that this specimen is suspected to be a novel Trypanosoma species. Further studies of this suspected new Trypanosoma species, including its vertebrate hosts and pathogenic potential, are therefore necessary.


Assuntos
DNA de Protozoário/genética , Insetos Vetores/classificação , Insetos Vetores/parasitologia , Phlebotomus/classificação , Phlebotomus/parasitologia , Trypanosoma/isolamento & purificação , Animais , Feminino , Insetos Vetores/genética , Masculino , Phlebotomus/genética , Tailândia , Trypanosoma/genética
10.
Artigo em Inglês | MEDLINE | ID: mdl-24964648

RESUMO

Leishmania siamensis is newly described as the causative pathogen of autochthonous leishmaniasis in Thailand. Potential vectors and animal reservoirs of L. siamensis are not thoroughly studied. An environmental survey was carried out in the affected area in two provinces in southern Thailand: Songkhla and Nakhon Si Thammarat. Ninety-nine villagers, 378 sandflies, and potential animal reservoirs were examined. Leishmania DNA amplicon was identified in two species of female sandflies, Sergentomyia (Neophlebotomus) and Sergentomyia (Parrotomyia) barraudi. The DNA amplicon was also identified in black rats (Rattus rattus). A phylogenetic tree of confirmed patients, sandflies and black rats fell into a single clade and separate from other Leishmania species. This study showed the potential involvement of R. rattus and Sergentomyia (Neophlebotomus and Parrotomyia) sandflies in transmission of L. siamensis.


Assuntos
Leishmaniose/genética , Leishmaniose/parasitologia , Psychodidae/parasitologia , Ratos/parasitologia , Animais , Reservatórios de Doenças , Feminino , Humanos , Insetos Vetores , Masculino , Filogenia , Reação em Cadeia da Polimerase , Tailândia/epidemiologia
11.
Malar J ; 13: 117, 2014 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-24670242

RESUMO

BACKGROUND: Drug resistance in Plasmodium falciparum is a major problem in malaria control especially along the Thai-Myanmar and Thai-Cambodia borders. To date, a few molecular markers have been identified for anti-malarial resistance in P. falciparum, including the P. falciparum chloroquine resistance transporter (pfcrt) and the P. falciparum multidrug resistance 1 (pfmdr1). However no information is available regarding the distribution pattern of these gene polymorphisms in the parasites from the Thai-Malaysia border. This study was conducted to compare the distribution pattern of the pfcrt and pfmdr1 polymorphisms in the parasites from the lower southern provinces, Thai-Malaysia border and the upper southern provinces, Thai-Myanmar border. In addition, in vitro sensitivities of anti-malarial drugs including chloroquine, mefloquine, quinine, and artesunate were determined. METHODS: In all, 492 P. falciparum-positive blood samples were collected from the lower southern provinces: Songkhla, Yala and Narathiwas. From the upper southern part of Thailand, Ranong and Chumphon, 66 samples were also collected. Polymorphisms of the pfcrt and the pfmdr1 gene were determined using PCR techniques. In vitro sensitivities of anti-malarial drugs were determined using radioisotopic method. RESULTS: All parasites from both areas contained the pfcrt 76 T allele. The pfmdr1 86Y allele was significantly more common in the parasites isolated from the lower southern areas. In contrast, the pfmdr1 184F allele was predominant among the parasites from the upper southern areas especially Ranong. In addition, the parasites from Ranong contained higher copy numbers than the parasites from other provinces. All adapted parasite isolates exhibited CQ-resistant phenotype. Neither QN nor MQ resistance was detected in these isolates. CONCLUSION: The parasites from Thai-Malaysia border exhibited different resistant patterns compared to other areas along the international border of Thailand. This information will be useful for anti-malarial drug policy in Thailand.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Antimaláricos/farmacologia , Resistência a Medicamentos , Malária Falciparum/tratamento farmacológico , Proteínas de Membrana Transportadoras/genética , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Humanos , Proteínas de Membrana Transportadoras/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Polimorfismo Genético , Proteínas de Protozoários/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Tailândia
12.
Am J Trop Med Hyg ; 89(6): 1081-7, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24127167

RESUMO

A four-year longitudinal cohort and geographic cluster study in rural Thailand was conducted to characterize the clinical spectrum of dengue virus (DENV) infection. Symptomatic DENV infections in the cohort were detected by active school absence-based surveillance that triggered cluster investigations around ill cohort children. Data from 189 cohort children with symptomatic DENV infection and 126 contact children in the clusters with DENV infection were analyzed. Of infected contacts, only 19% were asymptomatic; 81% were symptomatic, but only 65.9% reported fever. Symptom-based case definitions were unreliable for diagnosis. Symptomatic infections in contacts were milder with lower DENV RNA levels than the cohort. Infections in contacts with fever history were more likely to have detectable DENV RNA than infections without fever history. Mild infections identified by cluster investigations account for a major proportion of all DENV infections. These findings are relevant for disease burden assessments, transmission modeling, and determination of vaccine impact.


Assuntos
Vírus da Dengue/isolamento & purificação , Dengue/epidemiologia , RNA Viral/sangue , Adolescente , Criança , Pré-Escolar , Análise por Conglomerados , Estudos de Coortes , Dengue/transmissão , Dengue/virologia , Vírus da Dengue/genética , Feminino , Febre , Humanos , Lactente , Estudos Longitudinais , Masculino , População Rural , Tailândia/epidemiologia
13.
Trans R Soc Trop Med Hyg ; 107(12): 789-96, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24052594

RESUMO

BACKGROUND: In 2008, a chikungunya epidemic occurred in Southern Thailand. In many epidemics, there is a sizable number of asymptomatic cases. It is uncertain whether symptomatic and asymptomatic cases share the same risk factors. METHODS: Residents aged 18 years or more from three villages were sampled, their venous blood tested for anti-chikungunya virus IgG (haemagglutination-inhibition [HI] technique), and a face-to-face interview conducted during a home visit. RESULTS: Of 507 subjects selected, 314 (61.9%) were seropositive (HI titre≥1:10), of whom 148 (47.1%) were asymptomatic. Among subjects who reported fever and joint pain during the epidemic, 166 (97.1%) still had a positive titre. Having a garbage pile nearby and spending at least eight hours per day outdoors were associated with an increased risk of both symptomatic and asymptomatic chikungunya infection. Protective factors for symptomatic infection were age more than 58 and having a high level of formal education. CONCLUSIONS: Transmission was determined by environmental conditions whereas symptoms were associated with personal biological factors and social setting.


Assuntos
Febre de Chikungunya/epidemiologia , Vírus Chikungunya/imunologia , Escolaridade , Imunoglobulina G/sangue , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Artralgia/epidemiologia , Artralgia/virologia , Infecções Assintomáticas/epidemiologia , Febre de Chikungunya/sangue , Febre de Chikungunya/prevenção & controle , Exposição Ambiental , Feminino , Resíduos de Alimentos , Testes de Inibição da Hemaglutinação , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Tailândia/epidemiologia , Adulto Jovem
14.
Trop Med Int Health ; 18(2): 230-6, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23217082

RESUMO

OBJECTIVES: To assess the feasibility of conducting standard indoor space spraying using ultra-low-volume (SID-ULV) in terms of willingness to pay (WTP) and ability to pay (ATP) and ability to conduct space spraying by local administrative organisations (LAO) in lower Southern Thailand. METHODS: Cross-sectional study. The executive leaders of each LAO were asked to state their WTP and ATP for SID-ULV. Willingness to pay was measured by the payment card and open-ended question methods. Ability to pay was calculated using the budget allocation for space spraying and estimated expenditure for SID-ULV. Ability to conduct the SID-ULV was assessed by interviewing the spraymen. Average WTP and ATP were calculated and uncertainties were estimated using a bootstrapping technique. RESULTS: Ninty-three percent of executive leaders were willing to pay for SID-ULV. The average WTP per case was USD 259 (95% confidence interval [CI] 217-303). Thirty-eight percent of all LAO had actual ATP and 60% had ideal ATP. The average annual budget allocated for space spraying was USD 2327 (95% CI: 1654-3138). The amount of money LAO were willing to pay did not vary significantly between their different types, but ATP did. Thirty-two percent of spraymen could not complete all nine procedures of SID-ULV. CONCLUSIONS: Although WTP for SID-ULV space spraying was high, ATP was low, which revealed the flexibility of budget allocation for SID-ULV in each LAO. The spraymen require training in SID-ULV space spraying.


Assuntos
Dengue/prevenção & controle , Insetos Vetores/efeitos dos fármacos , Inseticidas/economia , Controle de Mosquitos/métodos , Aedes , Animais , Custos e Análise de Custo , Estudos Transversais , Financiamento Pessoal , Humanos , Inseticidas/administração & dosagem , Saúde Pública/economia , Saúde Pública/métodos , Tailândia/epidemiologia
15.
Artigo em Inglês | MEDLINE | ID: mdl-23077841

RESUMO

Antibody-dependent enhancement of infection (ADE) is central to explaining the development of severe disease at the end of post-dengue virus infection. Non-neutralizing anti-dengue antibodies bound to the dengue virion enhances the virus entrance into the target cells via the Fc receptor. The titer of enhancing antibodies in dengue patients is not determined during dengue virus infection. Sensitive flow cytometry detecting dengue virus-infected K562 cells was used to quantitate enhancing activity among Thai DF and DHF patients against four serotypes and the patient's dengue isolate. The titer was defined as the reciprocal of the final dilution that loses enhancing activity. The serum of Thai patients confirmed to have dengue infection were found to have high titers of enhancing antibodies and increased gradually through the convalescent phase of infection. The enhancing antibody titers were not different among the four serotypes or from the infecting isolate. The anti-dengue antibodies from dengue patients can enhance dengue virus infections in a concentration-dependent, serotype-independent manner.


Assuntos
Anticorpos Facilitadores/imunologia , Dengue/imunologia , Anticorpos Bloqueadores/imunologia , Anticorpos Antivirais/imunologia , Dengue/diagnóstico , Dengue/epidemiologia , Dengue/virologia , Citometria de Fluxo , Humanos , Células K562 , Receptores Fc/imunologia , Sorotipagem , Dengue Grave/diagnóstico , Dengue Grave/epidemiologia , Dengue Grave/imunologia , Dengue Grave/virologia , Tailândia/epidemiologia
16.
Artigo em Inglês | MEDLINE | ID: mdl-23077843

RESUMO

Dengue fever (DF), dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) are the re-emerging infectious diseases caused by dengue (DEN) virus, transmitted by Aedes mosquito. There are more than 100,000 cases of dengue infection and more than 100 deaths annually in Thailand. Virological surveillance for DEN viruses is used as an early warning system to predict outbreaks. The seroprevalence of infection and serotypes of DEN virus in 116 pediatric patients at Si Sa Ket Province, Thailand were analyzed during June to September 2004. At the same period, Aedes mosquitoes were caught from patients' and their neighbors' houses, from control houses, located in villages with no report of dengue infection during the previous 3 years. The majority of DHF cases were secondary infections of DEN-2 and DEN-4 serotypes. Of the 1,652 Aedes mosquitoes collected 1,583 were Ae. aegypti and 69 Ae. albopictus. Ten mosquitoes from each house were pooled and dengue viruses were determined using RT-PCR assay; only 1 positive pooled was found. Although the dengue infection rate in the field caught mosquitoes was low, the existing dengue virus control program in transmission areas by aerial spraying to destroy the larva breeding sites should be continued.


Assuntos
Aedes/virologia , Vírus da Dengue , Dengue/diagnóstico , Aedes/classificação , Animais , Dengue/sangue , Dengue/epidemiologia , Dengue/virologia , Feminino , Humanos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Estudos Soroepidemiológicos , Sorotipagem , Dengue Grave/sangue , Dengue Grave/diagnóstico , Dengue Grave/epidemiologia , Dengue Grave/virologia , Tailândia/epidemiologia
17.
Trop Med Int Health ; 17(6): 767-74, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22943302

RESUMO

OBJECTIVES: To access the costs of standard indoor ultra-low-volume (SID-ULV) space spraying for controlling dengue vectors in Thailand. METHODS: Resources related to SID-ULV space spraying as a method to control dengue vectors between July and December 2009 were identified, measured and valued taking a societal perspective into consideration. Information on costs was collected from direct observations, interviews and bookkeeping records. Uncertainty of unit costs was investigated using a bootstrap technique. RESULTS: Costs of SID-ULV were calculated from 18 new dengue cases that covered 1492 surrounding houses. The average coverage of the SID-ULV was 64.4%. In the first round of spraying, 53% of target houses were sprayed and 44.6% in the second round, of which 69.2% and 54.7% received entire indoor space spraying. Unit costs per case, per 10 houses and per 100 m(2) were USD 705 (95% Confidence Interval CI, 539-888), 180 (95% CI, 150-212) and USD 23 (95% CI, 17-30). The majority of SID-ULV unit cost per case was attributed to productivity loss (83.9%) and recurrent costs (15.2%). The unit cost of the SID-ULV per case and per house in rural was 2.8 and 1.6 times lower than municipal area. The estimated annual cost of SID-ULV space spraying from 2005 to 2009 using healthcare perspective ranged from USD 5.3 to 10.3 million. CONCLUSIONS: The majority of the cost of SID-ULV space spraying was attributed to productivity loss. Potential productivity loss influences the achievement of high coverage, so well-planned SID-ULV space spraying strategies are needed to reduce costs.


Assuntos
Aedes , Dengue/prevenção & controle , Habitação , Insetos Vetores , Inseticidas/economia , Controle de Mosquitos/economia , Animais , Custos e Análise de Custo , Humanos , Controle de Mosquitos/métodos , Estudos Prospectivos , Saúde Pública/economia , Saúde Pública/métodos , População Rural , Tailândia , População Urbana
18.
PLoS Negl Trop Dis ; 6(7): e1730, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22816001

RESUMO

BACKGROUND: Based on spatiotemporal clustering of human dengue virus (DENV) infections, transmission is thought to occur at fine spatiotemporal scales by horizontal transfer of virus between humans and mosquito vectors. To define the dimensions of local transmission and quantify the factors that support it, we examined relationships between infected humans and Aedes aegypti in Thai villages. METHODOLOGY/PRINCIPAL FINDINGS: Geographic cluster investigations of 100-meter radius were conducted around DENV-positive and DENV-negative febrile "index" cases (positive and negative clusters, respectively) from a longitudinal cohort study in rural Thailand. Child contacts and Ae. aegypti from cluster houses were assessed for DENV infection. Spatiotemporal, demographic, and entomological parameters were evaluated. In positive clusters, the DENV infection rate among child contacts was 35.3% in index houses, 29.9% in houses within 20 meters, and decreased with distance from the index house to 6.2% in houses 80-100 meters away (p<0.001). Significantly more Ae. aegypti were DENV-infectious (i.e., DENV-positive in head/thorax) in positive clusters (23/1755; 1.3%) than negative clusters (1/1548; 0.1%). In positive clusters, 8.2% of mosquitoes were DENV-infectious in index houses, 4.2% in other houses with DENV-infected children, and 0.4% in houses without infected children (p<0.001). The DENV infection rate in contacts was 47.4% in houses with infectious mosquitoes, 28.7% in other houses in the same cluster, and 10.8% in positive clusters without infectious mosquitoes (p<0.001). Ae. aegypti pupae and adult females were more numerous only in houses containing infectious mosquitoes. CONCLUSIONS/SIGNIFICANCE: Human and mosquito infections are positively associated at the level of individual houses and neighboring residences. Certain houses with high transmission risk contribute disproportionately to DENV spread to neighboring houses. Small groups of houses with elevated transmission risk are consistent with over-dispersion of transmission (i.e., at a given point in time, people/mosquitoes from a small portion of houses are responsible for the majority of transmission).


Assuntos
Aedes/virologia , Vírus da Dengue/isolamento & purificação , Dengue/transmissão , Dengue/virologia , Transmissão de Doença Infecciosa , Adolescente , Animais , Anticorpos Antivirais/sangue , Criança , Pré-Escolar , Análise por Conglomerados , Estudos de Coortes , Dengue/epidemiologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Lactente , Estudos Longitudinais , Masculino , Reação em Cadeia da Polimerase , População Rural , Tailândia/epidemiologia
19.
J Infect Dis ; 206(3): 389-98, 2012 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-22615312

RESUMO

BACKGROUND: The understanding of dengue virus (DENV) transmission dynamics and the clinical spectrum of infection are critical to informing surveillance and control measures. Geographic cluster studies can elucidate these features in greater detail than cohort studies alone. METHODS: A 4-year longitudinal cohort and geographic cluster study was undertaken in rural Thailand. Cohort children underwent pre-/postseason serology and active school absence-based surveillance to detect inapparent and symptomatic dengue. Cluster investigations were triggered by cohort dengue and non-dengue febrile illnesses (positive and negative clusters, respectively). RESULTS: The annual cohort incidence of symptomatic dengue ranged from 1.3% to 4.4%. DENV-4 predominated in the first 2 years, DENV-1 in the second 2 years. The inapparent-to-symptomatic infection ratio ranged from 1.1:1 to 2.9:1. Positive clusters had a 16.0% infection rate, negative clusters 1.1%. Of 119 infections in positive clusters, 59.7% were febrile, 20.2% were afebrile with other symptoms, and 20.2% were asymptomatic. Of 16 febrile children detected during cluster investigations who continued to attend school, 9 had detectable viremia. CONCLUSIONS: Dengue transmission risk was high near viremic children in both high- and low-incidence years. Inapparent infections in the cohort overestimated the rate of asymptomatic infections. Ambulatory children with mild febrile viremic infections could represent an important component of dengue transmission.


Assuntos
Vírus da Dengue/isolamento & purificação , Dengue/epidemiologia , Viremia/epidemiologia , Adolescente , Criança , Pré-Escolar , Análise por Conglomerados , Estudos de Coortes , Dengue/diagnóstico , Dengue/virologia , Feminino , Habitação , Humanos , Incidência , Lactente , Estudos Longitudinais , Masculino , Estudos Prospectivos , População Rural , Instituições Acadêmicas , Tailândia/epidemiologia , Fatores de Tempo , Viremia/diagnóstico , Viremia/virologia
20.
J Trop Med ; 2012: 652564, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22505942

RESUMO

Timely and extensive space spraying has been widely used to prevent the spread of dengue fever/dengue hemorrhagic fever (DF/DHF). Field evaluations on its effectiveness have been rarely reported. This study aimed to evaluate the timeliness, coverage, and effectiveness of space spraying for DF/DHF control using a geographic information system (GIS). Longitudinal monitoring of DF/DHF cases and spray activities in Songkhla municipality was done between May 2006 and April 2007. After a case was detected, subsequent cases occurring within a 100 meter radius of the index case's house and between 16-35 days of onset were considered as potential secondary cases. During the study period, 140 cases of DF/DHF were detected. Of these, 25 were identified as secondary infections from 20 index cases. Where a secondary infection occurred, the mean attack rate was 2.7 per 1,000 population. Two significant predictors for being a secondary case were both related to the house of the index case, namely, absence of window screens and being constructed with corrugated iron sheets. Our findings suggest that space spraying in the study area was inadequate and often failed to prevent secondary cases of DF/DHF. Control programs should target houses constructed with corrugated iron sheets.

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