Battling vectors amidst pollution

April 2015

There is an effective way to tackle the undesirable effects of contamination and pollution says Mohammad Arif Hussain, entomologist at Masa (pictured)

Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution.

Pollution may muddy landscapes, poison soils and waterways, or kill plants and animals. Humans are also regularly harmed by pollution. Long-term exposure to air pollution, for example, can lead to chronic respiratory disease, lung cancer and other diseases. Toxic chemicals that accumulate in top predators can make some species unsafe to eat.

Pesticide emissions can result during the manufacturing, formulation, transport, storage and application process. These can lead to accidental exposures which may have unfortunate consequences to man and the environment. It is indeed regrettable that such an ecologically disruptive and crude technology as pesticide use has to be widely available even before man has a good understanding of its effects on him and his environment. Environmental contamination is usually associated with the persistence of pesticides.

Some disasters give rise to increases in populations of vector or nuisance species, usually insects or rodents. Floods may create new mosquito breeding sites in rubble and stagnant pools. A general breakdown of sanitation may favour the multiplication of houseflies and rodents. People living in partially destroyed houses or primitive shelters may have lost the normal protection afforded by screened windows or mosquito nets.

Serious infection hazards may arise when massive migrations bring people of different origins together in temporary camps infested with disease vectors. Under such conditions, people who are relatively immune carriers of parasites can set off a disease transmission cycle to which weaker people and people who are not immune fall victim. Examples of disease outbreaks observed in such situations include malaria (transmitted by Anopheles mosquitoes), epidemic typhus (transmitted by lice) and dengue fever (transmitted by Aedes mosquitoes).

When wild or domestic host animals have been killed or driven away by disaster, ectoparasites, such as ticks, bugs, lice and fleas, may invade a community and produce a serious additional risk of zoonotic vector-borne disease. Another, related vector-borne disease risk may arise when refugees enter territory formerly occupied only by wildlife and accompanying parasites. Examples of diseases that may then emerge include plague (from rats) and Lyme disease (from ticks). When action against such pest organisms is considered during disasters, a distinction must be made between disease control and nuisance control.


A stagnant pool, source of proliferation of disease-giving organisms

A stagnant pool, source of proliferation of disease-giving organisms

Vector reduction

Reducing the population density of vectors and nuisance species is achieved by measures directed at the breeding sites: environmental management (drainage, filling, levelling of depressions and borrow pits, etc) or the use of insecticides (larvicides). In the latter case, the target organisms must be susceptible to the chemical. In addition, this chemical should not kill nontarget organisms (such as fish) or present a hazard to people drinking water from the same source.

Insecticides for killing adult vectors must be applied in places where the vector will rest, such as the inside surfaces of houses in the case of Anopheles mosquitoes, or cracks in walls and other hiding places in the case of triatomid bugs. In addition, the target species must be susceptible to the chemical and the chemical must not be a health hazard to the population or personnel carrying out the spraying. The design and implementation of these measures must therefore be the responsibility of specialised personnel.

Even if the most appropriate immediate response to vector or pest outbreaks is chemical control, sustained spraying is generally not recommended unless there are no other, more sustainable alternatives. A procedure such as environmental management, which has more long-lasting effects, will contribute to a healthier environment and thus to vulnerability reduction in the population concerned. The timing of the switch from chemical control to other methods will depend on many factors: environmental management may not be the preferred choice as long as life threatening hazards exist. It is often advisable to pursue the two approaches at the same time.


Hygiene and guidance

For instance, insecticides may be used for rapid reduction of the adult fly population during a Shigella dysentery outbreak, at the same time when refuse control and excreta control measures are taken to reduce opportunities for fly breeding. Such an integrated approach requires clear decision-making criteria and procedures adapted to local conditions. Whereas environmental management aims to protect populations from the risks of vector borne disease transmission, hygiene and personal protection are measures intended for individuals. Population-based interventions will do much to protect each individual in a disaster-stricken community if undertaken properly. However, some vulnerable groups, such as the sick and wounded, children, the elderly, pregnant women and people who lack immunity (including relief workers), may need additional protection. Information on both hygiene and personal protection should be provided to the public in the same way as any other health education message. Personal protection measures that involve the use of vaccines, drugs (for example prophylaxis) or pesticides (for example in impregnated mosquito nets) should be promoted by qualified health staff and used under their guidance.


On duty: a Masa worker

On duty: a Masa worker

Masa expertise

To protect the health and Environment, Masa uses the safest techniques, equipment and pesticides which leave residue only at the most minimum level. The equipment it deploys minimises pesticides spillage. One of the chemicals it uses for termite proofing is Imidacloprid 30.5 per cent SC as a termiticide which is registered at the  Saudi Food and Drug Authority (SFDA) under the Masa brand name Raslan Plus. Thanks to the use of this chemical and a very special spraying device there is no risk to health because the treated soil is covered by concrete.

Masa is also a distributor of some other chemicals and devices. It has a proven track record of 35 years’ experience in the field of pest control for delivering quality and effective results which are obtained through the use of a wide range of tried and tested solutions. It has a range of effective solutions at its disposal that ensure compliance with strict pest control legislation.

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