Dengue fever has the greatest incidence of all arbovirus infections. Dengue is considered to be the most important mosquito borne viral disease to affect humans. There are more than 30 million cases per year with tens of thousands of deaths. Depending upon the year, thousands of cases Dengue Hemorrhagic Fever (DHF) may also occur. Left untreated, the mortality rate of DHF is about 20%; the case mortality rate is about 5% in most countries. Dengue affects people living in the tropics and sub-tropics. Dengue is caused by one of four dengue virus serotypes of the flavivirus genus. The viruses that cause dengue fever are maintained in a cycle that involves humans and the mosquito Aedes aegypti. This is a domestic day-biting mosquito that prefers to feed on humans. Epidemics caused by multiple serotypes result in DHF. International outbreaks of mosquito borne Dengue and DHF are becoming increasingly more prevalent.

The reasons for this dramatic global emergence of dengue/DHF as a major public health problem are complex and not well understood. However, several important factors can be identified. First, effective mosquito control is virtually nonexistent in most dengue-endemic countries. Considerable emphasis for the past 20 years has been placed on ultra-low-volume insecticide space sprays for adult mosquito control with little to no quality control of the equipment or the chemical. Second, major global demographic changes have occurred, the most important of which have been uncontrolled urbanization and concurrent population growth. These demographic changes have resulted in substandard housing and inadequate water, sewer, and waste management systems, all of which increase Ae. aegypti population densities and facilitate transmission of dengue fever. As urbanization increases, the breeding grounds of Ae. aegypti also increases. Third, increased travel by airplane provides the ideal mechanism for transporting dengue viruses between population centers of the tropics, resulting in a constant exchange of dengue viruses and other pathogens. Lastly, in most dengue endemic countries the public health infrastructure has deteriorated. Limited financial and human resources and competing priorities have resulted in a "crisis mentality" with emphasis on implementing so-called emergency control methods in response to epidemics rather than on developing programs to prevent epidemic transmission. This approach has been particularly detrimental to dengue control because, in most countries, surveillance is very inadequate; the system to detect increased transmission normally relies on reports by local physicians who often do not consider dengue in their differential diagnoses. As a result, an epidemic has often reached or passed transmission before it is detected.

No dengue vaccine is available. Attenuated candidate vaccine viruses have been developed; however, an effective dengue vaccine for public use will not be available for many years.

Prospects for reversing the recent trend of increased epidemic activity and geographic expansion of dengue are not promising, thus new integrated mosquito control techniques must be emphasized that will economically curtail the outbreak.

Clarke has developed a system of control techniques called Clarke Dengue Control Solutions where new application techniques are integrated with traditional dengue control strategies to increase the likelihood of controlling or preventing a dengue fever emergency. These techniques should be combined with community participation efforts to reduce larval breeding sources and educating the public.

The following provides an integrated approach utilizing the Clarke Dengue Control Solutions:

Residual Indoor Space Spray Application (R.I.S.S.A.)
Clarke Mosquito Control and researchers from Walter Reed Army Medical Hospital recently investigated a revolutionary method to control dengue vectors in house-to-house applications. This method has proven to be more efficient, economical and effective than traditional house-to-house thermal fogging applications during an emergency situation. While it is well known that thermal fogging and ULV sprays are not residual applications, this research indicates that when using the Leco P-II Portable ULV Sprayer combined with a specific mosquito control formulation, will provide a residual effect as well as an airborne contact kill via ULV particles for indoor applications.

The new Leco P-1 Portable ULV Sprayer and a specially micronized Triton SC are the key components to this application.

About the Product: Triton SC is a high performance insecticide containing a resolved alphacypermethrin. The product is milled to a specific micron size in order to provide an extended residual when applied through the Leco P-1 ULV sprayer. A single application lasts for several weeks, does not build up in the environment and is extremely effective. The droplets contain sticky crystalline particles manufactured to a specific size, which adhere to many types of surfaces. The particles do not get absorbed like other formulations. Triton is odorless and low in mammaliam toxicity. It has two modes of action: It works as a contact kill via airborne aerosol particles expelled by the Leco P-1 Portable ULV Sprayer and through ingestion. When the mosquito comes into contact with Triton it begins to clean itself thus ingesting the product due to excito-repellancy reflex. The active ingredient operates by blocking the passage of sodium ions through the channels in the nerve membrane, preventing nerve impulses, thus killing the mosquito. Flush time occurs within 5 minutes and knockdown and mortality occurs within 30 minutes. In the RISSA application, the mosquito is exposed to several particles while in flight and while harboring in suitable resting spots within the house, thus diminishing its chance of recovery.

Even though Triton is relatively low in toxicity, however it is recommended that precautions be taken. Make sure occupants leave dwelling during the application and for at least 15 minutes afterwards. Cover food sources and eating areas. When spraying, wear a suitable respirator and wear protective clothing.

About the Equipment: The Leco P-1 Portable ULV Sprayer uses the same advanced engineering and quality construction concepts as the WHOPES approved Leco truck mounted sprayers. The lightweight, balanced design, cantilevered carrying handle and auxiliary shoulder strap combine to make this a versatile unit that is easy to carry and efficient to use. This technique allows for the product to be applied as a spray, but provides a residual barrier for several weeks.

The Leco P-1 utilizes an extremely durable 4-cycle piston port engine to drive a Clarke designed, positive displacement blower for ULV applications.

The Dengue Control Nozzle
Use Clarke Mosquito Control's latest technology IHPLAT: Industrial High Performance Laminar Airflow Technology. Utilizing IHPLAT technology, the nozzle produces a narrow particle spectrum with over 98% of the particles less than 20 microns. The Clarke Dengue Control Nozzle can be easily retrofitted on any existing Leco ULV sprayer. This nozzle provides quieter operation while facilitating greater penetration of vegetation with higher air velocity discharge than current Leco nozzles. The dengue nozzle contains no nylon or plastic parts. The nozzle is precisely machined to provide high performance during heavy use and instant cut-off.

Clarke 1% Skeeter Abate Sachet
Clarke has been a pioneer in mosquito control applications since the 1940's. We are constantly striving to identify new ways to apply insecticides to make them safer to the applicator and to the environment. Clarke scientists have developed a novel presentation of the traditional public health insecticide temephos used in dengue control programs. This new technique provides increased efficacy, efficiency and promotes the judicious use of the insecticide. This novel presentation is known as 1% Skeeter Sachet The Sachet contains 20 grams of temephos 1%SG. The temephos used in the Sachet is manufactured according to the WHO specifications for technical material and formulated product: WHO/SIT/19.R4 andWHO/SIF/40.R1.

Compared to traditional applications of bulk temephos, the Sachets have numerous advantages:

Leco Vector Control (VC) ULV Sprayer
Clarke has designed the new Leco Vector Control ULV. The Leco VC ULV was designed specifically for vector control programs. It provides the professional performance of all larger sprayers in an economical size and price. This ULV cold aerosol generator is lightweight and easy to operate. It features a high output rate while operating efficiently and quieter than larger units. Its 8 horsepower engine and 12 liter fuel tank allows the engine to run for more than nine hours continuously. This is longer running time than even the world renowned Leco 1800E.

Eclipse AQ/OS ULV
Few adult control products have been specifically designed for vector control. As a result, agriculture chemicals have been used in mosquito control, which are not intended for its use. As a result, misuse of insecticide occurs leading to injury, poor efficacy, resistance, harm to the environment and the need for more expensive and toxic chemicals.
Eclipse AQ/OS ULV was specifically developed for mosquito control to manage both nuisance and disease vectors. Eclipse AQ/OS ULV contains the active ingredients: alphacypermethrin, piperonyl butoxide and D-trans allethrin. Alphacypermethrin is a highly active synthetic pyrethroid insecticide, piperonyl butoxide acts as a synergist and D-trans allethrin is a knockdown agent. These three active ingredients, when combined, provide a tough resistance-fighting product. Eclipse AQ/OS ULV is scientifically synergized to maximize the effectiveness of the alphacypermethrin and d-trans allethrin. The allethrin causes hyper-activation of the insect and ultimately increased uptake of the insecticidal spray. The synergist delays the onset of resistance. The synergist also inactivates the detoxification systems in the mosquito. Since Eclipse AQ/OS is a concentrate, it is very economical to use once diluted. Eclipse can be diluted with either mineral oil or water.