Glossary of terms of common use in the OCP

WORLD HEALTH ORGANIZATION ONCHOCERCIASIS CONTROL PROGRAMME IN WEST AFRICA GLOSSARYOFTERMS of common use in the OCP August 1990 Term Definition blindness breeding site carry CMFL CMFL/AC cMFL/C detailed mapping DMFC electromorph endo mf epidemiological evaluation epidemiological surveillance epidemiological mapping exo mf fixed inversion floating inversion inability to count fingers at 3 metres with the better eye rapid current of a river with supports (vegetation and rocks) that can make possible the development of larvae and pupae of S. damnosum s.l. distance over which an insecticide sprayed at a given point is effective against the larvae of S. damnosum s.l. Community Microfilarial Load, i.e. the geometric mean mf/s among persons aged 20 years or more. the geometric mean MFAC among persons examined ophthalmologically. the goemetric mean DMFC among persons examined ophthalmologically. epidemiological mapping in order to identify communities with a high risk of oncho blindness to be included in morbidity control with ivermectin mass treatment. dead mf in the cornea banding patterns representing the isozyme products of a single allele which are observed after electrophoretic run and staining microfilariae, ingested by the vector, are imprisoned in the peritrophic membrane and digested. They have no role in onchocerciasis transmission. assessment of the epidemiological impact of control. epidemiological surveys undertakn to detect possible recrudescence of infection. description of the geographical distribution of the prevalence and intensity of onchocerciasis infection in a given area. mircofilariae of O. volvulus, ingested by the vector ,S. danutosunt s.I., which have escaped the peritrophic membrane and can be found either in the stomach, abdomen or thorax of the fly. These microfilariae can develop and evolve into sausage stage, stage 2, stage 3 and infective stage. an inversion occuring homozygously in all members of a particular species. It is intra-specific and therefore diagnostic. an inter-specific .inversion being absent or present in either a homozygous or heterozygous state in different individuals of the same species. the probability of (super)infection per unit of time.force- of- i n fecti on Term Definition forest flies form holo-endemic host-parasite model hyper-endemic hypo-endemic infected (inf) flies infective (inv) infective larva intermediate zone interruption of transmission ln verslon karyotype longevity of infection mass treatment meso-endemic mf MFAC mfls members of the Simulium damnosum species complex in West Africa - distinguished cytotaxonomically as: S. sanctipauli sub-complex (forms of S. soubrense, S. sanctipauli, S. konkourense and S. leonense), S. squamosum s.str., .s. yahense and morphologically by generally having dark wing tufts, long (in relation to thorax length) antennae and dark fore-coxae. a loose term applied to geographical variants of a particular species which show some genetical distinctiveness but being found in allopatric situations have not been given formal taxonomic ranking. community with a CMFL greater than 40 mf/s an epidemiological model which describes the dynamics of the parasite and its reproduction in a human host population. prevalence of skin snip positives of 60% or more in a community. prevalence of skin snip positives of less than 35% in a community. flies with any Onchocerca parasite stage (Ll,LZ or L3) in their head, thorax or abdomen. flies with L3 Onchocerca parasites in their heads. L3 of O. volvulus in the head of the vector S. dantnosunt s.l. interphase between savanna and forest bio-ecological zones. elimination of the inoculation of infective larvae in the human population. a mutation characterized by the reversal of the linear order of genes in a chromosome segment. the number, size and configuration of the chromosomes of a cell or organism. period between inoculation of L3 and death of the last mf due to this onchocerciasis infection. drug treatment of the whole eligible population irrespective of being infected or not. prevalence between 350/o and 600/0. microfilariae, i.e. the offspring of the adult O. volvulus mf in the anterior chamber of the eye mf per skin snip. Term Definition mf load mf repopulation neonate nulliparous ocular load old parous onchocerciasis infection Original Programme area parous parous infective polytene chromosome population pre-mature period pre-patent period prevalence of disease, mf, eye conditions, infection. recrudescence of infection recrudescence of disease retnyasron microfilarial density. build-up of microfilarial density after their reduction or elimination by chemotherapy. adult flies newly hatched from pupae - usually those reared from pupae in the laboratory. adult female flies which may or may not have taken a blood meal but have never laid eggs. microfilarial density in the eye. distinguished from other parous flies by having clear transparent malpighian tubules. inoculation of L3 larva and the subsequent development of one adult fertilized female worm which produces mf. total Programme area less the extension areas. adult female flies which have laid at least one batch of eggs. parous female having at least one infective larva in the head. a giant formed from repeated DNA replications without accompanying nuclear divisions such that it shows a specific banding pattern. a community of potentially inter-breeding individuals at a given locality. period between inoculation of an L3 larva and the time of its sexual maturation. period between inoculation of L3 larva and first appearance of mf in the skin due to this onchocerciasis infection. proportion of a population which has disease, mf, eye condition, infection. renewed transmission and the subsequent build-up of the prevalence and intensity of infection to near pre-control levels if no intervention is undertaken. recrudescence of infection and the subsequent build-up of disease to near pre-control levels if no intervention is undertaken. long-distance movement of savanna vectors into a controlled area - confirmed by the absence of local bredding and the high parous rate of the fly population. the period of fecundity of a female adult worm.reproductive lifespan aTerm Del'rnition sayanna flies sibling species skin snip skin snip positive SOSQU Southern Extension area species stained dissection standardized prevalence su peri n fec tion sympa try Western Extension area members of the Simulium damnosum species complex in West Africa - distinguished cytotaxonomically as: S. sirbanum, S. damnosun s.str., S. dieguerense or S. sudanense and morphologically by generally having pale wing tufts, short (in relation to thorax length) antennae and pale fore-coxae. reproductively isolated populations that show little or no morphological distinctiveness. skin biopsy for microscopic examination for presence of mf. presence of mf in a skin biopsy shown by microscopic examination. flies identified morphologically as forest species but not S. yahense - i.e. members of the S. sanctipauli sub-complex or S. squamosum. southern part of Benin, Togo and Ghana in which larviciding started as from 1986/87. groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups (Mayr, 1963). parous flies stained in Mayer's Acid Haemalum to improve the detection and measurement of parasites. prevalence expressed in relation to a reference population. a new onchocerciasis infection in a person who already is harbouring at least one onchocerciasis infection. the occurence of two or more species together in space and time. western part of Mali, Senegal, Guinea, Sierra Leone and Guinea-Bissau where larviciding started as from 1986/87.