Encuesta 2017-2018: Conocimientos, actitudes y práticas de los pobladores del Chaco paraguayo sobre las enfermedades infecciosas desatendidas y el dengue, Resultados / Survey 2017-2018: Knowledge, attitudes and practices of the inhabitants of the Paraguayan Chaco on neglected infectious diseases and dengue, Results

La presente publicación describe los conocimientos, actitudes y prácticas de los pobladores de los tres departamentos del Chaco Paraguayo sobre existencia de enfermedad, modo de trasmisión y sintomatología de las Enfermedades infecciosas desatendidas (EID y dengue. Asimismo, las actitudes de los pobladores del Chaco paraguayo en relación con la responsabilidad personal y comunitaria para prevenir las EID y el dengue

Characteristics of a dengue outbreak in a remote pacific island chain--Republic of The Marshall Islands, 2011-2012.

Dengue is a potentially fatal acute febrile illness caused by four mosquito-transmitted dengue viruses (DENV-1-4). Although dengue outbreaks regularly occur in many regions of the Pacific, little is known about dengue in the Republic of the Marshall Islands (RMI). To better understand dengue in RMI, we investigated an explosive outbreak that began in October 2011. Suspected cases were reported to the Ministry of Health, serum specimens were tested with a dengue rapid diagnostic test (RDT), and confirmatory testing was performed using RT-PCR and IgM ELISA. Laboratory-positive cases were defined by detection of DENV nonstructural protein 1 by RDT, DENV nucleic acid by RT-PCR, or anti-DENV IgM antibody by RDT or ELISA. Secondary infection was defined by detection of anti-DENV IgG antibody by ELISA in a laboratory-positive acute specimen. During the four months of the outbreak, 1,603 suspected dengue cases (3% of the RMI population) were reported. Of 867 (54%) laboratory-positive cases, 209 (24%) had dengue with warning signs, six (0.7%) had severe dengue, and none died. Dengue incidence was highest in residents of Majuro and individuals aged 10-29 years, and ∼95% of dengue cases were experiencing secondary infection. Only DENV-4 was detected by RT-PCR, which phylogenetic analysis demonstrated was most closely related to a virus previously identified in Southeast Asia. Cases of vertical DENV transmission, and DENV/Salmonella Typhi and DENV/Mycobacterium leprae co-infection were identified. Entomological surveys implicated water storage containers and discarded tires as the most important development sites for Aedes aegypti and Ae. albopictus, respectively. Although this is the first documented dengue outbreak in RMI, the age groups of cases and high prevalence of secondary infection demonstrate prior DENV circulation. Dengue surveillance should continue to be strengthened in RMI and throughout the Pacific to identify and rapidly respond to future outbreaks.

RNAi-mediated gene knockdown and in vivo diuresis assay in adult female Aedes aegypti mosquitoes.

This video protocol demonstrates an effective technique to knockdown a particular gene in an insect and conduct a novel bioassay to measure excretion rate. This method can be used to obtain a better understanding of the process of diuresis in insects and is especially useful in the study of diuresis in blood-feeding arthropods that are able to take up huge amounts of liquid in a single blood meal. This RNAi-mediated gene knockdown combined with an in vivo diuresis assay was developed by the Hansen lab to study the effects of RNAi-mediated knockdown of aquaporin genes on Aedes aegypti mosquito diuresis. The protocol is setup in two parts: the first demonstration illustrates how to construct a simple mosquito injection device and how to prepare and inject dsRNA into the thorax of mosquitoes for RNAi-mediated gene knockdown. The second demonstration illustrates how to determine excretion rates in mosquitoes using an in vivo bioassay.

Biology-based mapping of vector-borne parasites by geographic information systems and remote sensing.

Application of growing degree day-water budget analysis and satellite climatology to vector-borne parasites will be reviewed to demonstrate the value of using the unique thermal-hydrological preferences and limits of tolerance of individual parasite-vector systems to define the environmental niche of disease agents in the landscape by modern geospatial analysis methods. Applications of geospatial modeling will be illustrated by examples on fascioliasis, malaria, leprosy and leishmaniasis.

Transmission of viable Mycobacterium leprae by Aedes aegypti from lepromatous leprosy patients to the skin of mice through interrupted feeding.

Female Aedes aegypti which took partial blood meals from the skin lesions of untreated lepromatous leprosy (LL) patients were then allowed to continue feeding on 72-96-hr-old Swiss albino suckling mice (Rockefeller strain). The bitten portion of skin was removed, divided into two parts and processed for the extraction of bacilli by two different methods using chloroform and petroleum ether. The proboscis of some of the fed mosquitoes was dissected out and examined for viable bacilli (stained by fluorescein diacetate and ethidium bromide) and acid-fast bacilli (AFB). Out of 50 probosces dissected 45 were found positive for AFB, with bacillary counts ranging up to 246 (average 40.20 +/- SD 41.80) per proboscis. The average percentage of viable bacilli (green solid) in the probosces immediately after feeding on LL patients was 43.90 and thereafter it decreased gradually to 3 on the seventh day. In the petroleum ether extract of mouse skin viable bacilli were observed in numbers up to 37 (average 15.25 +/- SD 10.25) per smear. The number of fluorescing bacilli (green and red) correlated with the total number of AFB.

Transmission of Mycobacterium leprae from lepromatous leprosy patients to the skin of mice through intermittent feeding.

Batches of hungry Aedes aegypti mosquitoes which partially sucked blood from the skin lesions of proved untreated lepromatous leprosy (LL) patients were allowed immediately to feed on a portion of the skin of a cleanly shaved swiss mouse. The portion of the skin was cut, homogenized on the same day and extracted with chloroform. Out of 10 extracts, stained for acid fast bacilli (AFB), Mycobacterium leprae were demonstrated in eight, indicating transfer of bacilli mechanically to the biting spot through intermittent feeding. Out of 50 probosces dissected and stained for AFB, M. leprae were demonstrated in 45.

Persistence and distribution of Mycobacterium leprae in Aedes aegypti and Culex fatigans experimentally fed on leprosy patients.

Laboratory reared Aedes aegypti and Culex fatigans were experimentally fed on untreated lepromatous leprosy patients and the proboscides, guts and faeces of the mosquitoes were examiend at 12 hour intervals to determine the persistence and distribution of Mycobacterium leprae. In A. aegypti, bacilli persisted in proboscis till 156 hours, in gut 96 hours, and in faeces 72 hours after feeding. In C. fatigans--proboscides 144 hours, gut 96 hours and faeces 72 hours after feeding. In A. aegypti solid bacilli were present in proboscis upto 96 hours; in gut 48 hours and in faeces 42 hours after feeding. Corresponding figures for C. fatigans were: 144 hours for proboscis, 48 hours for gut, solid bacilli being absent in faeces. The results are discussed from the point of view of arthropod transmission.

Transfer of leprosy bacilli from patients to mouse footpads by Aedes aegypti.

Aedes aegypti mosquitoes which were first allowed to feed on untreated lepromatous leprosy patients, and then to refeed on mouse footpads were found to transfer Mycobacterium leprae to the footpads as seen by the subsequent multiplication of the bacilli in the footpads. Results presently available are insufficient to come to any conclusion about the actual role of mosquitoes in the transmission of leprosy in the field.