Larvacide: Controlling Mosquito Spread Of West Nile Virus In The United States - Thesis Example

Larvacide: Controlling Mosquito Spread Of West Nile Virus In The United States Introduction Larvicides are biological or chemical products used to kill immature mosquitoes before they become adults. The biological products are usually toxins from specific bacteria that is lethal to mosquito larvae leaving other organisms and the adults mosquitoes alive due to its selective nature (CDC, 2013). The chemical products mainly contain the insect growth regulators, surface films, or organophosphates and they mainly used with enough care due to their effects both to the environment and to human beings. The Larvicides are applied directly to water sources since these are the breeding grounds for mosquitoes since they hold both the larvae, mosquito eggs and pupae. The adulticides are also similar products used to reduce the population of mosquitoes only that they are used to kill adult mosquitoes while larvicides are for young mosquitoes. Adulticides are used when people need rapid results since they kill the adult mosquitoes with the capability of causing West Nile Virus when they bite people (West nile virus facts, 2013). CDC position on chemical mosquito control Chemicals when used in large quantities have the possibility to cause hazard and should thus be closely monitored and regulated lest we pollute the environment. Chemical control measures are part of the mosquito management strategy used with great caution so as to avoid the negative effects to the environment. Integrated mosquito management program have several component and they include; reduction of mosquito breeding sites and surveillance aimed at identifying and reducing the mosquito life cycle programs (CDC, 2001). West Nile Virus (WNV) This is a mosquito transmitted member of the genius Flavivirus and genus Flaviridae and it become a potential public health threat in 1950 when it was associated with epidemics of fever and encephalitis in the Middle East. WNV has been associated with sporadic outbreaks of human disease across the world with frequent outbreaks witnessed in Mediterranean basin and large outbreaks witnessed in Romania and Russia. Today, WNV has become enzootic disease in all 48 states of America with transmission evident in the form of infected humans, mosquitoes, birds horses and other mammals due to its ability to exist in wide ecosystems. WNV is present in 65 different mosquito species which are distributed in most parts of the world making it a potentially harmful disease. The most important vectors include Cx.pipens, Cx Quinquefascitus and Cx Pipens ans quinquefascitus, distributed in most parts of the united states of America (CDC, 2013). Distribution of WNV vectors in different parts of U.S Adapted from http://www.cdc.gov/westnile/resources/pdfs/wnvguidelines.pdf Due to the frequent and extensive distribution of WNV, it’s the most frequent cause of arboviral disease in more than two-thirds of the United States of counties since it’s widely distributed. The infection of humans is witnessed every month of the year with intense infection witnessed in winter. The surveillance system for WNV consists of epidemiology surveillance and environmental surveillance and they work complementarily. Epidemiological surveillance utilizes WNV human disease to quantify disease burden while environmental surveillance monitors the local WNV activity in vector and non human vertebrate hosts.. In addition to this, epidemiological surveillance also detects and quantifies alternative routes of WNV transmission to humans thus helping drawing the preventive measures. WNV is mostly transmitted to humans through the bite of infected mosquitoes with rare cases of person to person transmission reported. Person to person transmission mainly occurs through infected blood products or solid organ transplantation, thus routine screening of such products is necessary to avoid further transmission. About 70% of human WNV infections are subclinical or asymptomatic with most symptomatic persons experiencing acute systemic febrile illness associated with headache, myalgia and gastrointestinal symptoms (CDC, 2013). Larval mosquito control The objective of larval mosquito control is to reduce the mosquito populations before they become adults and pose serious health hazards. This is an efficient IPM program aimed at managing mosquitos from their breeding sites and killing them at larval stages so as to reduce the adult populations before they reach their infectious stage. This method id effective in controlling young mosquitoes but it must be accompanied by measures of controlling adult mosquitoes as well in order to achieve meaningful progress. Caution should betaken since larval control alone cannot be able to stop the WNV outbreaks once the virus has stared causing infections and this is the reason it should be accompanied by adulticides control. Among the numerous methods available for controlling larval mosquitoes include the source reduction so as to remove the potential breeding sites. The use of larvicides is also very effective in controlling young mosquitos as they are killed when thy come into contact with these compounds hence reducing their populations drastically (NPIC, 2013). Contrast between Larvacide and adulticides The main contrast between larvicides and adulticides is that larvicides are targeted in controlling young mosquitos before they reach their adult stage and cause WNV in humans. Adulticides are targeted in controlling adult mosquitos with the potential of causing WNV and they cannot be used to eradicate the mosquito larvae. When the mosquito population is reduced at larval stage, their general population is expected to reduce drastically since there will be no adults in future to continue the breeding program. Breeding grounds for young mosquitos are also easy to spot and eradicate than to track the adult mosquitos hence the use of larvicides is effective method in reducing the spread of WNV in future (ASTDR, 2003). Environmental safety Most of the insecticides are from pyrethrins and pyrethroids and they have the potential of causing heath complications if not properly used according to the labels. The effect of exposure to these substances is hazardous depending on the dose and the duration of exposure and therefore, care should be taken before their application. High levels of pyrethrins and pyrethroids cause dizziness, headache, convulsions, and in extreme cases, it can cause loss of consciousness in human beings or even animals. Pyrethrins are naturally occurring compounds with insecticidal properties in pyrethrum extracts while pyrethroids are manufactured chemicals with similar working pattern hence are mostly used to kill insects. More than 1000 pyrethroids have been developed but less than a dozen of them are being used in Unites States since thy use is highly discouraged due to their negative effects (ASTDR, 2003). Pyrethroids normally enter the environment as insecticidal sprays and are normally broken down rapidly within two days by sunlight then they bind strongly into the soil. The Larvacide and Adulticides are also insecticides and thus can be made from pyrethrins and pyrethroids hence they should be used with great caution lest they cause health hazards to users and also to the environment (NPIC, 2013). The environmental protection agency (EPA) and CDC recognizes the threat exposed by control of WNV hence recommends Integrated Pest Management (IPM) approach to prevent the spread of the virus with minimal negative effects to the environment. The IPM approach encompasses WNV surveillance and monitoring, sanitation, maintenance, biological and chemical control in the modest way. The public should also be educated on the best ways to handle these methods in such a way as to cause minimal damage to the environment. The two pesticides used control mosquitoes are larvicides and adulticides and they are applied in low volumes and are designed to break down quickly after spray hence lowers their potential to pollute the environment. The public are also encouraged to use mosquito repellants to minimize the rate of mosquito bites and reduce the rate of WNV infection. When these measures are used collectively, they represent a more reliable means of controlling the population of mosquitos and the spread of WNV infections. Mosquito control applications have been evaluated by EPA and proven to be environmental safety compliance hence pose minimal risk to human health when use in accordance to the labels. The ultra low volume applications of the insecticides that control WNV are estimated by EPA as 100times lower than a pesticide that may pose health hazard (MDCH, 2013). This shows that these mosquito applicants are low risk and they are also continuously monitored by EPA for any health concerns that may arise. The mosquito control agencies are also applying technology so as to make the applications as precise as possible thus further reducing the levels of environmental damage. The agencies are using the Global Positioning Systems (GPS) in monitoring the target areas to improve aerial applications which can be applied in large scale in a short period of time. This enables them to apply the chemicals to targeted areas only thus reducing wastage and environmental degradation in equal measure. Lasers are used to measure the droplet size of insecticides dispersed while wind tunnels are used to stimulate flying conditions for quick and efficient testing of spraying systems and for optimal droplet sizes. The mosquito control applications are highly effective in preventing the spread of WNV as evident in Fort Collins where emergency application reduce the rate of attack from 211 to 17 within one season. The public have also been evaluated in the use of pesticides in controlling WNV and a whooping nine out of ten supported the these initiative an evidence which shows that the public greatly support the use of these measures. Cities practicing the use of larvicides Several states in the Unites State where WNV is prevalent are known to practice the use of larvicides with cities such as New York being in the frontline in its application. New Jersey is also a city in which many cases of WNV is prevalent are applying the use of larvicides to control the mosquito population. References ASTDR, (2003). Pyrethrins and Pyrethroids. Agency for Toxic Substances and Disease Registry. Atlanta, U.S.A. CDC, (2001). Emerging infectious diseases. A peer Reviewed Journal Tracking and Analyzing Disease Trends. Vol, 17. No, 4. Available at CDC website. CDC, (2013). West Nile Virus in the United States: Guidelines for Surveillance, Prevention, and Control. U.S. Department of Health and Human Services Public Health Service. Fort Collins, Colorado MDCH, (2013). Michigan Department of Community Health. West Nile Virus. Retrievd from www.michigan.gov NPIC, (2013). National Pesticides Information Centre: Mosquito Control Methods. Retrieved from http://npic.orst.edu/pest/mosquito/control.html West nile virus facts, (2013). Preventing West Nile Virus: West Nile Virus Facts. Retrievd from www.westnilevirusfacts.org Read More