Optimization of Slash and Clear Community-Directed Control of Simulium damnosum Sensu Stricto in Northern Uganda.

Onchocerciasis, caused by infection with Onchocerca volvulus, has been targeted for elimination by 2030. Currently, onchocerciasis elimination programs rely primarily on mass distribution of ivermectin. However, ivermectin alone may not be sufficient to achieve elimination in some circumstances, and additional tools may be needed.

Identification of Human-Derived Attractants to Sensu Stricto in the Madi-Mid North Onchocerciasis Focus of Uganda.

Human landing collections (HLCs) have been the standard method for the collection of black flies that serve as vectors for , the causative agent of onchocerciasis or river blindness. However, HLCs are inefficient and may expose collectors to vector-borne pathogens. The Esperanza window trap (EWT) has been shown to be a potential alternative to HLCs for the collection of , the principal vector of in Africa.

Accelerating river blindness elimination by supplementing MDA with a vegetation "slash and clear" vector control strategy: a data-driven modeling analysis.

Attention is increasingly focusing on how best to accelerate progress toward meeting the WHO's 2030 goals for neglected tropical diseases (NTDs). For river blindness, a major NTD targeted for elimination, there is a long history of using vector control to suppress transmission, but traditional larvicide-based approaches are limited in their utility. One innovative and sustainable approach, "slash and clear", involves clearing vegetation from breeding areas, and recent field trials indicate that this technique very effectively reduces the biting density of Simulium damnosum s.

Optimization and evaluation of the Esperanza Window Trap to reduce biting rates of Simulium damnosum sensu lato in Northern Uganda.

Background: Onchocerciasis, or river blindness, has historically been an important cause of blindness, skin disease and economic disruption in Africa and the Americas. It is caused by the filarial parasite Onchocerca volvulus, which is transmitted by black flies in the genus Simulium. Over the past decade, several international programs have been formed to control, or more recently eliminate onchocerciasis, using mass drug administration (MDA) of ivermectin.

Elimination of onchocerciasis in Africa by 2025: the need for a broad perspective.

Background: In response to the recent publication "Is onchocerciasis elimination in Africa feasible by 2025: a perspective based on lessons learnt from the African control programmes" by Dadzie et al., it is important to clarify and highlight the positive and unequivocal research and operational contributions from the American experience towards the worldwide elimination of human onchocerciasis (river blindness).

Main Text: The strategies of twice or more rounds of mass drug administration (MDA) of ivermectin per year, as well as the use of OV-16 serology have allowed four American countries to be verified by World Health Organization to have eliminated transmission of Onchocerca volvulus, the etiological agent.

Community-directed vector control to supplement mass drug distribution for onchocerciasis elimination in the Madi mid-North focus of Northern Uganda.

Background: Onchocerciasis a neglected tropical disease that historically has been a major cause of morbidity and an obstacle to economic development in the developing world. It is caused by infection with Onchocerca volvulus, which is transmitted by black flies of the genus Simulium. The discovery of the potent effect of Mectizan (ivermectin) on O.

The esperanza window trap reduces the human biting rate of Simulium ochraceum s.l. in formerly onchocerciasis endemic foci in Southern Mexico.

Background: The Esperanza Window Trap (EWT) baited with CO2 and human sweat compounds is attractive to Simulium ochraceum s.l., the primary vector of Onchocerca volvulus in the historically largest endemic foci in México and Guatemala.

Skin snips have no role in programmatic evaluations for onchocerciasis elimination: a reply to Bottomley et al.

A critique of the recommendation that skin snips be used for post-MDA surveillance of formerly endemic onchocerciasis areas is provided. After considering several fundamental aspects of the use of this methodology within the context of prolonged mass distribution of ivermectin, we argue that skin-snipping has no value for monitoring onchocerciasis elimination programs.

Identification of semiochemicals attractive to Simulium vittatum (IS-7).

Many blackfly species (Diptera: Simuliidae) are economically important insect pests, both as nuisance biters and as vectors of pathogens of medical and veterinary relevance. Among the important blackfly pest species in North America is Simulium vittatum Zetterstedt sensu lato. The objective of this study was to identify compounds excreted by mammalian hosts that are attractive to host-seeking S.

One Hundred Years After Its Discovery in Guatemala by Rodolfo Robles, Onchocerca volvulus Transmission Has Been Eliminated from the Central Endemic Zone.

We report the elimination of Onchocerca volvulus transmission from the Central Endemic Zone (CEZ) of onchocerciasis in Guatemala, the largest focus of this disease in the Americas and the first to be discovered in this hemisphere by Rodolfo Robles Valverde in 1915. Mass drug administration (MDA) with ivermectin was launched in 1988, with semiannual MDA coverage reaching at least 85% of the eligible population in > 95% of treatment rounds during the 12-year period, 2000-2011. Serial parasitological testing to monitor MDA impact in sentinel villages showed a decrease in microfilaria skin prevalence from 70% to 0%, and polymerase chain reaction (PCR)-based entomological assessments of the principal vector Simulium ochraceum s.

Elimination of Onchocerciasis from Mexico.

Background: Mexico is one of the six countries formerly endemic for onchocerciasis in Latin America. Transmission has been interrupted in the three endemic foci of that country and mass drug distribution has ceased. Three years after mass drug distribution ended, post-treatment surveillance (PTS) surveys were undertaken which employed entomological indicators to check for transmission recrudescence.

Identification of communal oviposition pheromones from the black fly Simulium vittatum.

The suite of pheromones that promote communal oviposition by Simulium vittatum, a North American black fly species, was identified and characterized using gas chromatography-mass spectrometry, electrophysiological, and behavioral bioassays. Behavioral assays demonstrated that communal oviposition was induced by egg-derived compounds that were active at short range and whose effect was enhanced through direct contact. Three compounds (cis-9-tetradecen-1-ol, 1-pentadecene, and 1-tridecene) were identified in a non-polar solvent extract of freshly deposited S.

Identification of human semiochemicals attractive to the major vectors of onchocerciasis.

Background: Entomological indicators are considered key metrics to document the interruption of transmission of Onchocerca volvulus, the etiological agent of human onchocerciasis. Human landing collection is the standard employed for collection of the vectors for this parasite. Recent studies reported the development of traps that have the potential for replacing humans for surveillance of O.

Evaluation of a community-based trapping program to collect Simulium ochraceum sensu lato for verification of onchocerciasis elimination.

Background: Collection of the black fly vectors of onchocerciasis worldwide relies upon human landing collections. Recent studies have suggested that the Esperanza Window Trap baited with a human scent lure and CO2 had the potential to replace human hosts for the collection of Simulium ochraceum sensu lato in Southern Chiapas focus, Mexico. The feasibility of utilizing these traps in a community-based approach for the collection of S.

Optimization of the Esperanza window trap for the collection of the African onchocerciasis vector Simulium damnosum sensu lato.

A simple inexpensive trap (Esperanza window trap) was shown recently to collect significant numbers of Simulium ochraceum sensu lato, a major vector of Onchocerca volvulus in Mesoamerica. Here, we report studies optimizing this trap for the collection of Simulium damnosum s.l.

Development of a novel trap for the collection of black flies of the Simulium ochraceum complex.

Background: Human landing collections are currently the standard method for collecting onchocerciasis vectors in Africa and Latin America. As part of the efforts to develop a trap to replace human landing collections for the monitoring and surveillance of onchocerciasis transmission, comprehensive evaluations of several trap types were conducted to assess their ability to collect Simulium ochraceum sensu lato, one of the principal vectors of Onchocerca volvulus in Latin America.

Methodology/principal Findings: Diverse trap designs with numerous modifications and bait variations were evaluated for their abilities to collect S.

Winter severity predicts the timing of host shifts in the mosquito Culex erraticus.

In temperate regions, seasonal epidemics of many mosquito-borne viruses are triggered when mosquito populations shift from feeding on avian to mammalian hosts. We investigated effects of temperature on the timing of bird-to-mammal shifts using an 8 year dataset of blood-meals from a mosquito (Culex erraticus) in Alabama, USA. As expected, Cx.

Importance of ivermectin to human onchocerciasis: past, present, and the future.

Ivermectin (registered for human use as Mectizan) was donated by Merck & Co Inc in 1987 for the treatment and control of human onchocerciasis ("river blindness"). This philanthropic gesture has had a remarkable effect in reducing the incidence and prevalence of this serious ocular and dermatological disease, while changing health system support for millions of people worldwide. Over 800 million doses have been given to more than 80 million people for onchocerciasis during the past 23 years.

Elimination of human onchocerciasis: history of progress and current feasibility using ivermectin (Mectizan(®)) monotherapy.

We review and analyze approaches over a 65 year period that have proven successful for onchocerciasis control in several different epidemiological settings. These include vector control with the goal of transmission interruption versus the use of mass drug administration using ivermectin (Mectizan(®)) monotherapy. Ivermectin has proven exceedingly effective because it is highly efficacious against Onchocerca volvulus microfilariae, the etiological agent of onchocercal skin and ocular disease and the infective stage for the vector.

Salivary gland thrombostasin isoforms differentially regulate blood uptake of horn flies fed on control- and thrombostasin-vaccinated cattle.

Thrombostasin (TS) is an anticlotting protein found in saliva of Haematobia irritans (horn flies). The polymorphic nature of the ts gene was first associated with success of horn flies blood feeding on a laboratory host, New Zealand White rabbits. In this study, we report results of similar studies testing blood uptake of horn flies feeding on a natural host, cattle.

Developing GIS-based eastern equine encephalitis vector-host models in Tuskegee, Alabama.

Background: A site near Tuskegee, Alabama was examined for vector-host activities of eastern equine encephalomyelitis virus (EEEV). Land cover maps of the study site were created in ArcInfo 9.2 from QuickBird data encompassing visible and near-infrared (NIR) band information (0.

Salivary gland thrombostasin isoforms differentially regulate blood uptake of horn flies fed on New Zealand White rabbits.

Thrombostasin (TS) is a previously characterized anticlotting protein with multiple isoforms found in the saliva of horn flies. In this report, the effect of TS isoforms on blood feeding was assessed using individual flies that carried corresponding ts allelles. Laboratory studies of horn fly blood feeding were conducted using colony-reared flies fed on New Zealand White (NZW) rabbits.

West Nile virus infection in mosquitoes in the mid-south USA, 2002-2005.

West Nile virus (family Flaviviridae, genus Flavivirus, WNV) was first detected in the Tennessee Valley and in Alabama in August 2001. In summer 2002, intensive viral activity was seen, but in subsequent years, viral activity settled into an enzootic pattern. Here, we report an analysis of viral activity in the mosquito fauna in the Mid-South from 2002 (the first year viral activity was detected in mosquitoes) through 2005.

A dynamic transmission model of eastern equine encephalitis virus.

Eastern equine encephalitis virus (EEEV) is one of several arthropod-borne viruses (arboviruses) endemic to the United States. Interactions between arthropod (mosquito) vectors and avian amplification host populations play a significant role in the dynamics of arboviral transmission. Recent data have suggested the hypothesis that an increased rate of successful feeding on young-of-the-year (YOY) birds might play a role in the dynamics of EEEV transmission.