Dengue research and training supported through the World Health Organization

Kroeger, Axel; Nathan, M. B.; Hombach, Joachim; Dayal-Drager, Renu; Weber, Martin

doi:10.1179/136485906x105642

Cited by 5 publications

(3 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This raises the question of whether permethrin-based insecticides should be replaced with other alternatives to maintain and restore susceptibility to pyrethroids. In addition to potentially improving vector control performance in the short term, this action also could protect the downstream potential for use of emerging vector control products impregnated with pyrethroids such as long-lasting textiles [15] , [16] , [73] . We do recognize the difficulties surrounding operational large-scale changes of insecticide use patterns but hope that our findings will help to inform the debate regarding the critical need to monitor and manage insecticide resistance in order to protect the limited options that are available to combat Ae.…”

Section: Discussionmentioning

confidence: 99%

Recent Rapid Rise of a Permethrin Knock Down Resistance Allele in Aedes aegypti in México

Flores²,

et al. 2009

View full text Add to dashboard Cite

Background Aedes aegypti, the ‘yellow fever mosquito’, is the primary vector to humans of dengue and yellow fever flaviviruses (DENV, YFV), and is a known vector of the chikungunya alphavirus (CV). Because vaccines are not yet available for DENV or CV or are inadequately distributed in developing countries (YFV), management of Ae. aegypti remains the primary option to prevent and control outbreaks of the diseases caused by these arboviruses. Permethrin is one of the most widely used active ingredients in insecticides for suppression of adult Ae. aegypti. In 2007, we documented a replacement mutation in codon 1,016 of the voltage-gated sodium channel gene (para) of Ae. aegypti that encodes an isoleucine rather than a valine and confers resistance to permethrin. Ile1,016 segregates as a recessive allele conferring knockdown resistance to homozygous mosquitoes at 5–10 µg of permethrin in bottle bioassays.Methods and FindingsA total of 81 field collections containing 3,951 Ae. aegypti were made throughout México from 1996 to 2009. These mosquitoes were analyzed for the frequency of the Ile1,016 mutation using a melting-curve PCR assay. Dramatic increases in frequencies of Ile1,016 were recorded from the late 1990's to 2006–2009 in several states including Nuevo León in the north, Veracruz on the central Atlantic coast, and Yucatán, Quintana Roo and Chiapas in the south. From 1996 to 2000, the overall frequency of Ile1,016 was 0.04% (95% confidence interval (CI95) = 0.12%; n = 1,359 mosquitoes examined). The earliest detection of Ile1,016 was in Nuevo Laredo on the U.S. border in 1997. By 2003–2004 the overall frequency of Ile1,016 had increased ∼100-fold to 2.7% (±0.80% CI95; n = 808). When checked again in 2006, the frequency had increased slightly to 3.9% (±1.15% CI95; n = 473). This was followed in 2007–2009 by a sudden jump in Ile1,016 frequency to 33.2% (±1.99% CI95; n = 1,074 mosquitoes). There was spatial heterogeneity in Ile1,016 frequencies among 2007–2008 collections, which ranged from 45.7% (±2.00% CI95) in the state of Veracruz to 51.2% (±4.36% CI95) in the Yucatán peninsula and 14.5% (±2.23% CI95) in and around Tapachula in the state of Chiapas. Spatial heterogeneity was also evident at smaller geographic scales. For example within the city of Chetumal, Quintana Roo, Ile1,016 frequencies varied from 38.3%–88.3%. A linear regression analysis based on seven collections from 2007 revealed that the frequency of Ile1,016 homozygotes accurately predicted knockdown rate for mosquitoes exposed to permethrin in a bioassay (R2 = 0.98).ConclusionsWe have recorded a dramatic increase in the frequency of the Ile1,016 mutation in the voltage-gated sodium channel gene of Ae. aegypti in México from 1996 to 2009. This may be related to heavy use of permethrin-based insecticides in mosquito control programs. Spatial heterogeneity in Ile1,016 frequencies in 2007 and 2008 collections may reflect differences in selection pressure or in the initial frequency of Ile1,016. The rapid recent increase in Ile1,016 is predicted by a...

show abstract

Section: Discussionmentioning

confidence: 99%

Recent Rapid Rise of a Permethrin Knock Down Resistance Allele in Aedes aegypti in México

Flores²,

et al. 2009

View full text Add to dashboard Cite

show abstract

“…Vaccine research is ongoing, thus control efforts currently focus on the principal mosquito vector, Aedes aegypti, with limited resources and often limited success. Innovative research in dengue surveillance and prevention aims to integrate emerging technologies into an effective multi-tiered approach for disease reduction 3,4. Dynamic estimations of risk are needed to guide the development of more effective surveillance-intervention strategies and use of prevention resources, especially for resource-limited, endemic countries that suffer recurrent epidemics with severe disease.…”

Section: Introductionmentioning

confidence: 99%

The Complex Relationship between Weather and Dengue Virus Transmission in Thailand

Campbell¹,

Lin²,

Iamsirithaworn³

et al. 2013

The American Society of Tropical Medicine and Hygiene

106

115

View full text Add to dashboard Cite

Using a novel analytical approach, weather dynamics and seasonal dengue virus transmission cycles were profiled for each Thailand province, 1983–2001, using monthly assessments of cases, temperature, humidity, and rainfall. We observed systematic differences in the structure of seasonal transmission cycles of different magnitude, the role of weather in regulating seasonal cycles, necessary versus optimal transmission “weather-space,” basis of large epidemics, and predictive indicators that estimate risk. Larger epidemics begin earlier, develop faster, and are predicted at Onset change-point when case counts are low. Temperature defines a viable range for transmission; humidity amplifies the potential within that range. This duality is central to transmission. Eighty percent of 1.2 million severe dengue cases occurred when mean temperature was 27–29.5°C and mean humidity was > 75%. Interventions are most effective when applied early. Most cases occur near Peak, yet small reductions at Onset can substantially reduce epidemic magnitude. Monitoring the Quiet-Phase is fundamental in effectively targeting interventions pre-emptively.

show abstract

“…The World Health Organization (WHO) recently launched a multi-country study to test a strategy of dengue surveillance and control based on the identification and removal/treatment of the most pupaproductive breeding sites (Focks and Alexander, 2006;Kroeger et al, 2006;Nathan et al, 2006). The aim of the present study, part of this larger investigation, was to evaluate the potential of pupal indices to characterise the entomological component of dengue transmission in Thailand.…”

mentioning

confidence: 99%

Assessment of a new strategy, based onAedes aegypti(L.) pupal productivity, for the surveillance and control of dengue transmission in Thailand

Barbazan

Tuntaprasart

Souris

et al. 2008

Annals of Tropical Medicine & Parasitology

View full text Add to dashboard Cite

In the countries where the disease is endemic, control of dengue is mainly based on the elimination or treatment of the water-filled containers where the main vector, Aedes aegypti, breeds, in interventions usually reliant on community participation. Although such control activities must be continuous, since vector eradication appears impossible, it should be possible to reduce the incidence of dengue significantly, in a cost-effective manner, by targeting only those types of containers in which large numbers of Ae. aegypti are produced. This strategy is now recommended by the World Health Organization, although it depends on the most productive types of container being carefully identified, in each endemic region. In Thailand, exhaustive surveys of 3125 wet containers in 240 houses in either an urban area (100-120 houses) or a rural area (120 houses) were conducted during a rainy and a dry season in 2004-2005. Indices based on the numbers of Ae. aegypti pupae observed were found to correlate with the 'classical' entomological indices that are based on all of the immature stages of the vector. Overall, 2.3 and 0.8 Ae. aegypti pupae were observed per person in the rural and urban areas, respectively. Although adult female Ae. aegypti laid eggs in all 10 types of wet container that were identified, large water-storage containers produced the majority of the pupae, especially at the end of the dry season (when such containers accounted for 90% of the pupae detected in the rural area and 60% of those in the urban area). Since these containers are large, easy to reach and account for, <50% of all wet containers, it should be relatively easy and quick to treat them with larvicide or to cover them. If even such targeted treatment is to be sustainable, however, it will have to be integrated, as one of several activities in which the at-risk communities are encouraged to participate.

show abstract

Dengue research and training supported through the World Health Organization

Cited by 5 publications

References 3 publications

Recent Rapid Rise of a Permethrin Knock Down Resistance Allele in Aedes aegypti in México

Recent Rapid Rise of a Permethrin Knock Down Resistance Allele in Aedes aegypti in México

The Complex Relationship between Weather and Dengue Virus Transmission in Thailand

Assessment of a new strategy, based onAedes aegypti(L.) pupal productivity, for the surveillance and control of dengue transmission in Thailand

Contact Info

Product

Resources

About