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La lutte antivectorielle en France

Didier Fontenille
Christophe Lagneau
Sylvie Lecollinet
et al.


Appendix 5. Glossary

Texte intégral

1Terms in bold type in definitions refer to another glossary entry.

2Adult trap: a trap used in collection for assessing the density of adult arthropods in search of their blood meal. The trap is generally built with a baited element incorporated (live bait, birds, mammals), chemical attractants or a light source with more or less specific wavelengths and a vacuum air-flow capture system. Capturing can also be achieved directly on a human or animal bait.

3Arboviroses: viral diseases caused by arboviruses. This is an epidemiological definition, not a virological one.

4Arboviruses: the whole range of viruses that are transmitted by haematophage arthropod vectors. This term does not belong to the taxonomic classification of viruses (they include different classes of virus). The name is derived from the contraction of the expression arthropod-borne virus.

5Arthralgia: pain in joints.

6Arthropod vectors: haematophage arthropods which, by specific behaviour patterns actively pass the pathogen (the vector plays an active role, bringing the pathogen to a receptive vertebrate) by biological transmission (cycle essential for development occurs in the vector) from a vertebrate host “donor” to another, receptive vertebrate host. The term parasite specificity is used. This infectious agent can be a bacterium, a virus, protozoan or helminth. N.B.: biological transmission is distinct from mechanical transmission (see this term).

7Arthropods: a branch of invertebrates (from the Greek arthron “joint” and podos “foot”). The arthropod body is formed out of jointed segments (or metameres), covered by a hard cuticle acting as their external skeleton, which in most cases is made of chitin. The insects form part of this branch and belong to the sub-branch hexapods (with three pairs of legs).

8Arthropods, haematophage: group gathering together arthropods needing a blood meal which provides them with the proteins required for producing eggs. In many cases therefore, only the female takes a blood meal. The principal haematophage arthropods belong to the sub-branch of hexapods (insects). They contain fleas (order Siphonaptera), mosquitoes, flies and gnats (order Diptera, family, Culicidae, Phlebotomidae, Ceratopogonidae, Simuliidae, Glossinidae and Tabanidae), body lice (order Phthirapterae) and the bugs (order Hemiptera). The ticks, hard (Ixodidae family) or soft (Argasidae family) are also haematophage but are included in the subbranch Arachnidae.

9Biocides: active substances and products presented in the form in which they are delivered to the end-user which are designed to destroy, repel or render nuisance organisms harmless, prevent their action or control them in any other way, by means of a chemical or biological action.

10Biological control: use of a “natural enemy” of an arthropod to reduce populations and hence the risk of pathogen transmission. Agents used for biological control can be divided into predators (fish predators of mosquito larvae) and pathogens (fungi, parasitoids).

11Biological transmission: biological phenomenon involving the accomplishment of a phase of the development cycle of a pathogen.

12Breeding sites: expression used widely in the scientific literature to designate the pools and lakes harbouring immature mosquitoes (eggs, larvae and nymphs).

13Chemical control: techniques using plant-derived or synthetic products as repellents, bait (combined with traps) or insecticides.

14Conformity assessment: evaluation of conformity by observation and judgment accompanied, if necessary, by measurements, trials or calibration (ISO 9000). Checking of validity.

15Criteria: variables that can take relevant and reliable account either of achievement of objectives, particularly variations in health, knowledge or attitudes, or of the different components of the programme.

16Culicidae: family of insects commonly called “mosquitoes”, belonging to the order Diptera (two wings), and to the suborder Nematocera (long antennae). The females of most species have long biting and sucking mouth parts. These are in the form of a long proboscis. The mosquito life-cycle proceeds in different stages: egg, an aquatic larva (4 larval phases) and the nymph which is also aquatic. The adult emerges from this nymph. It mates only once (the spermatozooa from the male are kept in the spermatheca of the female). The female will bite several times during its life in order to bring its eggs to maturity. Fertilization of these is activated at the moment of egg-laying. The lapse of time between two layings is termed the trophogonic or gonotrophic cycle.

17DFA: Départements français d’Amérique (French Departments of the Americas). These are Guadeloupe, French Guiana and Martinique.

18Diapause: period of inactivity during which the metabolism is slowed down and the insects’ development or growth is suspended. The eggs of some species can spend winter in diapause and hatch in spring when temperatures and the photoperiod are again favourable for development.

19Diptera: order of insects characterized by the presence of two wings (the second pair of wings is transformed into a balancing organ) and the mouth parts are used as sucking and biting apparatus.

20Diurnal: active in daytime.

21Econometrics: the body of statistical techniques devoted to measuring economic values and to practising economics research.

22Effectiveness: level of concretization of planned activities and of achieving the expected results (according to ISO 9000).

23Egg-laying trap: a tool that helps in detection of mosquito species that uses laying sites such as small recipients, sheath-like leaves or hollows in trees. The objective is to provide an artificial attractive egg-laying site for the target species, that is stable (staying firmly in place) and kept regularly in water, located in an environment that is itself attractive (dense vegetation, proximity of hosts). For example, for Aedes albopictus the trap consists of a labelled black bucket, containing water (prior infusion of dry wood), a pastille of insecticide and an egg-laying support made out of a square of polystyrene. This trap above all allows detection of the presence of a species in a previously unaffected zone. It could yield data on the density of the species in a colonized area if sampling is correctly accomplished. The egglaying traps are often employed in Aedes surveillance.

24Emerging disease: is a “disease whose real incidence grows significantly in a given population, in a given geographical zone and during a defined period compared with the usual epidemiological situation of this disease (unknown, rare, hypoendemic, and so on)”. This definition is equally applicable for diseases affecting humans, animals or plants. This emergence can be linked either to the appearance of a new pathogen, or a change in a known agent, such modification making it resistant to usually effective treatments, or pathogenic if it was previously non-infectious.

25Endemic: describes a situation where transmission of a pathogen occurs at a constant level over time; a level that can be either low or high. In strict usage, the term is restricted to human diseases.

26Endemization: the process by which a disease that has newly appeared maintains its presence in the area at a constant level.

27Enquiry: intellectual approach having the objective of discovering facts, improvement of knowledge or resolving doubts and problems.

28Environmental control: classifies all actions conducted on the environ-ment to make it hostile for the development of vector populations.

29Enzootic: term equivalent to endemic, but employed only for animal diseases.

30Epidemic: describes a situation where transmission of a pathogen occurs characterized by a rapid increase in the number of cases in a short period of time. After the peak of transmission, a fall in the number of cases is observed. In strict usage, the term is restricted to human diseases.

31Epidemization: a term used to characterize the process by which an endemic disease becomes epidemic.

32Epizooty: term equivalent to epidemic, but employed only for animal diseases.

33Extrinsic incubation period: in biological transmission, the lapse of time between the infecting blood meal and the moment when the vector, once infected, itself becomes able to infect. This should be called the extrinsic development period. Just after the blood meal that gives the infection, the pathogen cannot yet be transmitted, nor can it be inoculated into a new host during a new blood meal. The pathogen must generally clear several barriers for it to pass from the digestive tract to the salivary glands prior to inoculation. The extrinsic incubation period is of crucial importance for epidemiology. Its duration depends on the species, on the strain of parasite, the arthropod and factors linked to the environment (temperature, humidity and so on). The extrinsic cycle duration is variable, lasting between 2 and 15 days in tropical environments. N.B.: if the lapse of time is too long, the insect dies before becoming infectious. Conversely, if the duration of the extrinsic cycle is short, the bite from the infecting vector becomes infectious, either as soon as the next bite if this duration is shorter than the trophogonic cycle, or during the one after that. The older the vector becomes the more dangerous it is because it will have had several blood meals, thereby increasing the risk of becoming infected. One then talks of an epidemiologically dangerous age.

34Follow-up-assessment: combination of follow-up exercise and assessment which leads to the acquisition of information required and makes possible the critical reflection necessary for sound management of the project and for meeting the obligations of accountability.

35Genetic control: consists of employing any conditions and methods of treatment that might reduce the reproductive potential of nuisance organisms by modification or replacement of hereditary material.

36Gravid: term expressing the state of a female arthropod which, having brought its eggs to maturity, is seeking egg-laying sites.

37Haematophage: characterizes arthropods whose diet is partly composed of blood needed for the maturation of their eggs.

38Haematozoan: protozoan (consisting of a single cell) parasite of red blood cells.

39Imago: designates the final stage of development of an insect that has undergone its metamorphosis (adj. imaginal). It is the adult, reproductive stage, as opposed to the larval or nymphal stages which are incapable of reproduction.

40Indicators: concrete variable data, that can be simple or complex, quantitative or qualitative, whose follow-up and/or comparison in time (or space) can give a way of understanding or measuring changes (or differences) that have occurred. In reality, they give an expression of the chosen criterion. For example: the vector density or abundance vectors is a criterion, the entomological indices are indicators. Several indicators are normally needed to give a proper representation of a given criterion.

41Internal audit: an independent objective operation which gives an organization an assurance of the degree of command it has over its operations, provides it with advice for making improvements and contributes to creating added value. The process helps this organization to achieve its objectives by using a systematic and methodical approach to assess risk management processes, control and governance of the enterprise and putting forward propositions for enhancing their efficiency (Institut français de l’audit et du contrôle internes).

42Larva: immature form of insects undergoing complete metamorphosis, occurring between the egg and the nymph. Mosquito larvae are aquatic.

43Larval stage: period of development during which the series of larval moults occur in insects.

44Larvivorous: feeding off arthropod larvae.

45Management dashboard: synthetic representation of a set of indicators giving a manager all the elements enabling him visually and rapidly to take decisions.

46Mechanical control: grouped under this term are vector capture methods (with the objective of decreasing abundance), techniques that hinder host-vector contact and, by extension, methods that allow avoidance of contact with the host.

47Mechanical transmission: transmission effected at the time of two successive blood meals separated by a very short time interval (generally interrupted meals). The pathogen taken up during the first meal stays in the mouth parts and is then immediately re-injected during the second blood meal. In plant-pathogen vectors it has been shown, in the case of non circulative transmission (equivalent to mechanical transmission), that the pathogen fixation on the mouth parts was relatively specific, sometimes happening by the intermediary of a protein from the plant appropriated by the pathogen. Research has thus far never been done on this specificity in vectors of vertebrate pathogens, and the present doctrine assumes the absence of specificity. This transmission mechanism is highly dependent on the pathogen’s survival in the insect’s mouth parts. The HIV-Aids virus is not for example transmitted mechanically by haematophage arthropods.

48Nuisance: describes an arthropod which causes strong discomfort by its bites or presence but without disease transmission (for example, Aedes caspius in the Camargue ou Culicoides impunctatus (midges) in Scotland).

49Nymph: immature stage intermediate between larva and adult in insects undergoing complete metamorphosis.

50Organochloride: synthetic chemical product, derived from chlorine molecules and used as a solvent, insecticide, fungicide or refrigerant or in intermediary synthetic compounds in chemistry and pharmacy.

51Organophosphate: synthetic chemical products, derived from phosphorus molecules and used for a wide range of roles, such as insecticides, fungicides or refrigerants.

52Ornithophile mosquitoes: mosquitoes taking their blood meals predominantly from birds.

53Pour-on: an insecticide formulation used in veterinary medicine which is applied along the backbone of the animals and designed subsequently to diffuse over the whole of the animal’s body.

54Process: system of correlated or interacting activities which uses resources to transform input elements into output elements (definition derived from ISO standards).

55Resistance: genetic mechanism of tolerance to doses of toxic substances which would exert a lethal effect on the majority of individuals making up the normal population of the same species. Or: “Appearance in a population of insects of the faculty to tolerate doses of toxic substance which would exert a lethal effect on the majority of individuals composing a normal population of the same species” (WHO, 1957).

56Risk perception: a subjective judgment made on a threat in which an assessment of its probability/susceptibility/gravity interacts with sentiments/emotions which give it a value.

57Risk trade-off: expression of the transfer of detrimental phenomena from one source to another by an action aiming to reduce them (vector control, which aims to reduce the vector risk, can be the source of new, real or perceived, risks).

58Self-assessment: assessment conducted by those who manage a programme and/or take part in it in the field.

59Solenophage or “capillary feeding”: haematophage arthropods equipped with a long proboscis which perforates and catheterizes the blood capillaries to absorb blood. This group includes blood-sucking bugs, Culicidae and body lice.

60Standard: value associated with criteria (or with the indicator) considered as acceptable in the current state of knowledge.

61Telmophage or pool feeding: haematophage arthropods doted with a short proboscis adapted for lacerating, separating then absorbing the blood accumulated in a micro-haematoma. This group assembles the horse-flies (tabanids), blackfly (Simuliidae), Ceratopogonidae, Phlebotomidae and the ticks. This process also leads to take-up of pathogens present outside the blood circulation system, in the dermis.

62Ultra-Low Volume: spreading method based on the dispersal of wet-mixed or granulated insecticide at a volume lower than 5 l/ha.

63Vector capacity: ability for a vector to become infected on a vertebrate host, to enable a pathogen to develop and transmit this agent to another host in natural environmental conditions. This index expresses the number of infections that a given vector will cause per patient (index case or new autochthonous case) and per day in a non-immune population. This parameter depends on the vector competence, the vector-host contact rate, itself dependent on the trophic preference (choice of vertebrate species for the blood meal) and the abundance (vector density), and also the longevity of the vector (the longer the vector’s life-span, the more chance it will have had to become infected during a blood meal). The vector capacity also expresses the degree of parasite-vector coadaptation and the workings of the system in a given environment and a particular season. Vector capacity is measured for a given population (at a given place and time).

64Vector competence: intrinsic ability of the vector to become infected on a vertebrate host, ensure the development of a pathogen and transmit it to another host. This parameter can be measured in the laboratory and is determined genetically. It depends on the arthropod population.

65Vertical transmission: describes transmission, usually of the trans-ovarian type, of a pathogen, generally a virus, of a female to its descendants. This transmission is highly important in epidemiology because it maintains a virus in an environment unfavourable for transmission (cool season in a temperate zone, dry season in the tropical zone); it is the process that occurs in many arboviruses. It is different from the “traditional” host-vector-host horizontal transmission. N.B.: there are also cases of trans-stadial transmission (persistence of infection in spite of a change of stage, in certain ticks for example). In some rare cases, sexual transmission also occurs (infection of a female by an infected male, during mating). As mosquito males do not take a blood meal, sexual transmission implies a vertical form of transmission.

66Viraemia: period during which the pathogen is present in the bloodstream of the vertebrate host. If the arthropod vector is to become infected during a blood meal, the viral dose in the blood must reach a given threshold of infectivity. Similarly, the terms bacteraemia and parasitaemia are used for the presence in the blood respectively of bacteria and parasites.

67Zoonosis: animal disease transmissible to humans and vice versa (i.e. a human disease transmissible to animals).

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