There is a threat for dengue virus (DENV) reemergence in many regions of the world, particularly in areas where the DENV vectors, Aedes aegypti (L.) and Aedes albopictus (Skuse), are readily available. However, there are currently no accurate and reliable diagnostic methods to provide critical, real-time information for early detection of DENV within the vector populations to implement appropriate vector control and personal protective measures. In this article, we report the ability of an immuno-chromatographic assay developed by VecTOR Test Systems Inc. to detect DENV in a pool of female Aedes mosquitoes infected with any of the four viral serotypes. The DENV dipstick assay was simple to use, did not require a cold chain, and provided clear results within 30 min. It was highly specific and did not cross-react with samples spiked with West Nile, yellow fever, Japanese encephalitis, Rift Valley fever, chikungunya, Venezuelan equine encephalomyelitis, Ross River, LaCrosse, or Caraparu viruses. The DENV assay can provide real-time critical information on the presence of DENV in mosquitoes to public health personnel. Results from this assay will allow a rapid threat assessment and the focusing of vector control measures in high-risk areas.
Malaria diagnosis is largely dependent on the demonstration of parasites in stained blood films by conventional microscopy. Accurate identification of the infecting Plasmodium species relies on detailed examination of parasite morphological characteristics, such as size, shape, pigment granules, besides the size and shape of the parasitized red blood cells and presence of cell inclusions. This work explores misclassifications of four Plasmodium species by conventional microscopy relative to the proficiency of microscopists and morphological characteristics of the parasites on Giemsa-stained blood films.
Single Nucleotide Polymorphisms (SNPs) in the Pfmdr1, and Pfcrt, genes of Plasmodium falciparum may confer resistance to a number of anti-malaria drugs. Pfmdr1 86Y and haplotypes at Pfcrt 72-76 have been linked to chloroquine (CQ) as well as amodiaquine (AQ) resistance. mefloquine (MQ) and lumefantrine (LU) sensitivities are linked to Pfmdr1 86Y. Additionally, Pfcrt K76 allele carrying parasites have shown tolerance to LU. We investigated the association between Pfmdr1 86/Pfcrt 72-76 and P. falciparum resistance to CQ, AQ, MQ and LU using field samples collected during 2008-2011 from malaria endemic sites in western Kenya. Genomic DNA from these samples was genotyped to examine SNPs and haplotypes in Pfmdr1 and Pfcrt respectively. Additionally, immediate ex vivo and in vitro drug sensitivity profiles were assessed using the malaria SYBR Green I fluorescence-based assay. We observed a rapid but steady percent increase in wild-type parasites with regard to both Pfmdr1 and Pfcrt between 2008 and 2011 (p<0.0001). Equally, a significant reciprocate decrease in AQ and CQ median IC50 values occurred (p<0.0001) during the same period. Thus, the data in this study point to a significantly rapid change in parasite response to AQ and CQ in the study period. This may be due to releasing of drug pressure on the parasite from reduced use of AQ in the face of increased Artemisinin (ART) Combination Therapy (ACT) administration following the intervention of the Global Fund in 2008. LU has been shown to select for 76K genotypes, thus the observed increase in 76K genotypes coupled with significant cross resistance between LU and MQ, may herald emergence of tolerance against both drugs in future.
Rift Valley fever virus (RVFV) causes outbreaks of severe disease in domestic ungulates as well as humans in Africa. There is a concern that outbreaks of Rift Valley fever may continue and that this virus may spread into regions where it had not previously been detected. Surveillance and rapid detection are critical to the initiation of an effective disease control program. Here we report on the field evaluation in Kenya of the VectorTest RVFV antigen assay, modeled on the VecTest assay for West Nile virus. The dipsticks provided results in <20 min, were easy to use, and did not require a laboratory with containment facilities. Although none of the field-collected mosquitoes were infected with RVFV, the dipstick provided a clear positive result with pools of field-collected mosquitoes spiked with a single positive, irradiated (to inactivate any infectious virus) mosquito. Similarly, the dipstick was able to detect virus from pools of mosquitoes captured during the RVFV outbreak in 2007. The RVFV dipstick assay was highly specific with only a single weak false positive out of 266 pools tested (specificity > 99.6%). The RVFV assay can provide a rapid, safe, easy-to-use preliminary test to alert public health personnel to the presence of RVFV in mosquitoes in a given area. Results from this assay will allow for more rapid medical threat assessments and the focusing of vector control measures on high-risk areas.
Failure by individual service members and units to implement preventive measures to mitigate environmental health threats have always resulted in reduced efficiency of the Warfighter, with the attendant reduction in combat capability. This article describes observations at 2 sites in northern Iraq from July 2007 to September 2009 of deficiencies in the use of preventive and protective measures to reduce incidences of vector-borne diseases. Observations included individual service member s indifference or negative attitude toward use of personal protective equipment and unit leaders failure to provide required resources and enforce use of personal protective measures. Implications of these actions and recommendation for enhancing compliance are discussed.
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