Mosquitoes around the home can be reduced significantly by minimizing the amount of standing water available for mosquito breeding. Residents are urged to reduce standing water around the home in a variety of ways.
The best way is to avoid being bitten by mosquitoes.This can be accomplished using personal protecting while outdoors when mosquitoes are present. Treated bed nets should be used sleeping. Mosquito repellent should be used when outdoor.
Health officials in Ghana are eager to see the production of chemicals that kill malaria-causing mosquitoes in their larval stage.
This is informed by the realisation that the war against malaria will yield more progress if the vectors are killed before they grow up and start transmitting the disease.
To this end the governments of Ghana, Nigeria and other malaria-endemic countries have sought the expertise of Cubans to produce the chemical for large scale larviciding.
Larva is one of the four stages in a mosquito’s life cycle. Larviciding is a general term for killing immature mosquitoes by applying agents to control mosquito larvae and/or pupae. Most mosquito species spend much of their life cycle in the larval stage when they are highly susceptible to both predation and control efforts.
During the larval stage they often are concentrated within defined water boundaries, immobile with little ability to disperse. Adult mosquitoes, in contrast, fly in search of mates, blood meals, or water sources for egg laying and are often inaccessible, not concentrated, and widely distributed. Therefore, effective larviciding can reduce the number of adult mosquitoes available to spread disease, create a nuisance, and lay eggs which lead to more mosquitoes.
Larviciding techniques may include the addition of surface films to standing water to suffocate mosquito larvae. These larvicides will last only a few weeks in water and pose no danger to humans, non-targeted animal species, or the environment when used according to directions.
Source reduction of mosquitoes is seen as the most efficient and ecologically safe approach at controlling mosquitoes.
Mosquitoes breed in standing water. Without it they cannot continue their life cycle. The most common form of source reduction is dumping out containers around the home that create a habitat for mosquitoes to lay their eggs.
These containers should either be emptied every three days, or covered to prevent collecting water. It is important to note this because anytime mosquito-control personnel do an- around- the- home inspection, they commonly find that containers holding water are breeding mosquitoes.
Sources from the Health Ministry say the national agency has been carrying out larviciding through the district assemblies.
The source indicates that indoor residual spraying (IRS) as a measure, was not yielding the desired impact at controlling infection rates and preventing further deaths from the disease because “it is being carried out in only a few communities.”
Communities have also been unwilling to invite volunteers into their rooms to carry out IRS due to issues of privacy, although these volunteers are usually known to them. This makes larviciding a good choice.
Larviciding can reduce overall pesticide usage in a control program. Killing mosquito larvae before they emerge as adults can reduce or eliminate the need for ground or aerial application of pesticides to kill adult mosquitoes.
Interestingly however, experts have expressed misgivings about the exercise, labelling it a political eye service that will culminate in a huge waste of public funds. They have called for a modification of the exercise through a proper co-ordination by the National Malaria Control Programme (NMCP).
Mrs Aba Baffoe-Wilmot of the NMCP has explained to Eyes on Malaria that certain wrong notions have to be dispelled about the mosquitoes and their breeding places if larviciding is to succeed in reducing mosquito populations.
She said the anopheles gambiae which transmits malaria in our part of the world does not breed in dirty stagnant and toxic waters, as people often believe.
“These mosquitoes prefer to breed in shallow, stagnant water in sunlit places devoid of vegetation. Examples can be found in rice fields, puddles, rivulets, little containers and receptacles that collect fresh rain water.”
“Swampy lowland areas, new construction sites, ditches along roadways, flooded yards, storm sewers, and other small temporary impoundments of water are all potential sources of mosquito reproduction when water is stagnant for 6-10 days without treatment.”
She also explained the types of mosquito found in these dirty surroundings are not the ones responsible for the spread of malaria.
The medical entomologist deplored the resources spent by NGOs and stakeholders who have been spraying filthy toxic water bodies in the name of larviciding.
Mrs Baffoe-Wilmot recommended an environmental management of mosquito in what is termed “targeted larviciding.”
She said planning a larviciding strategy is crucial to an effective control program. The first step begins with adult and larval surveillance. Once surveys have been conducted, it is then important to map out and prioritize potential larval habitats.
The number of larvae encountered at a site, should be established to justify larviciding, and action plans made appropriate for the sites.
The larvae are unevenly distributed and the density where they do occur is much higher than at other times in their development when they tend to be more evenly dispersed.
Larvicides can be applied from either the ground by truck, boat, and hand held devices or by air with fixed wing and rotary wing aircraft.
Follow-up efficacy checks are important to ensure a successful larviciding program and rotation of products should be incorporated into any larva management program.
“Following the lessons learnt, the NMCP has developed closer relations with the Cuban larvicide firm called LabioPharm. We are doing larviciding in Greater Accra and Brong-Ahafo Regions to streamline the killing of mosquitoes at the larva stage. The NMCP is also collaborating with the Malaria Vector Control Oversight Committee (MaVCOC) to help achieve real results from larviciding,” said Madam Baffoe-Wilmot
“Larviciding is in urban areas because the WHO policy says to do larviciding you should find stagnant water, it should not be much, it should be fixed, so that you will be able to apply the medicine to it; that’s why we are doing it in the urban areas alone.”
“It is the hope of the NMCP that when targeting larviciding is done effectively, we could well be killing two birds with one stone because the anopheles mosquitoes spreading malaria are also responsible for the spread of elephantiasis.”
By Carlton Cofie