Vector control standard 2: Physical, environmental and chemical protection measures
The environment where the disaster-affected people are placed does not expose them to disease-causing and nuisance vectors, and those vectors are kept to a reduced level where possible.
Key actions (to be read in conjunction with the guidance notes)
Settle the displaced populations in locations that minimise their exposure to vectors, especially mosquitoes (see guidance note 1).
Clear and/or modify vector breeding and resting sites where practicable (see guidance notes 2–4).
Undertake intensive fly control in high-density settlements when there is a risk or the presence of a diarrhoea epidemic (see guidance note 2).
Provide working referral mechanisms for people infected with malaria for early diagnosis and treatment (see guidance note 5).
The population density of mosquitoes is kept low to avoid the risk of excessive transmission levels and infection (see guidance note 4).
- Fewer people are affected by vector-related health problems (see guidance notes 1–5).
1. Site selection is important in minimising the exposure of the affected population to the risk of vector-borne disease. This should be one of the key factors when considering possible sites. With regard to malaria control, for example, camps should be located 1–2 kilometres upwind from large breeding sites, such as swamps or lakes, whenever an additional clean water source can be provided (see Shelter and settlement standard 2, guidance notes 5–9).
2. Environmental and chemical vector control: There are a number of basic environmental engineering measures that can be taken to reduce the opportunities for vector breeding. These include the proper disposal of human and animal excreta (see Excreta disposal section), proper disposal of refuse in order to control flies and rodents (see Solid waste management section), drainage of standing water, and clearing unwanted vegetation cover around open canals and ponds to control mosquitoes (see Drainage section). Such priority environmental health measures will have some impact on the population density of some vectors. It may not be possible to have sufficient impact on all the breeding, feeding and resting sites within a settlement or near it, even in the longer term, and localised chemical control measures or individual protection measures may be needed. For example, spraying infected spaces may reduce the number of adult flies and prevent a diarrhoea epidemic, or may help to minimise the disease burden if employed during an epidemic.
3. Designing a response: Vector control programmes may have no impact on disease if they target the wrong vector, use ineffective methods or target the right vector in the wrong place or at the wrong time. Control programmes should initially aim to address the following objectives: reduce vector population density; reduce human–vector contact; and reduce vector breeding sites. Poorly executed programmes can be counterproductive. Detailed study and, often, expert advice are needed and should be sought from national and international health organisations. In addition, local advice should be sought on local disease patterns, breeding sites, seasonal variations in vector numbers and incidence of diseases, etc.
4. Environmental mosquito control: Environmental control aims primarily at eliminating mosquito breeding sites. The three main species of mosquitoes responsible for transmitting disease are Culex (filariasis), Anopheles (malaria and filariasis) and Aedes (yellow fever and dengue). Culex mosquitoes breed in stagnant water loaded with organic matter such as latrines, Anopheles in relatively unpolluted surface water such as puddles, slow-flowing streams and wells, and Aedes in water receptacles such as bottles, buckets, tyres, etc. Examples of environmental mosquito control include good drainage, properly functioning VIP (ventilated improved pit) latrines, keeping lids on the squatting hole of pit latrines and on water containers, and keeping wells covered and/or treating them with a larvicide (e.g. for areas where dengue fever is endemic).
5. Malaria treatment: Malaria control strategies that aim to reduce the mosquito population density should be carried out simultaneously with early diagnosis and treatment with effective anti-malarials. Such strategies will include eliminating breeding sites, reducing the mosquito daily survival rate and restricting the habit of biting humans. Campaigns to encourage early diagnosis and treatment should be initiated and sustained. An integrated approach, combining active case finding by trained outreach workers and treatment with effective anti-malarials, is more likely to reduce the malaria burden than passive case finding through centralised health services (see Essential health services – control of communicable diseases standard 2, guidance note 3).