| New World leishmaniasis | A grave disease caused by Leishmania braziliensis braziliensis, endemic in southern Mexico and Central and South America, except for the equatorial region of Chile; the organism does not invade the viscera, and the disease is limited to the skin and mucous membranes, the lesions resembling the sores of cutaneous leishmaniasis caused by L. Mexicana or L. Tropica; the chancrous sores heal after a time, but some months or years later, fungating and eroding forms of ulceration may appear on the tongue and buccal or nasal mucosa; many variants of the disease exist, marked by differences in distribution, vector, epidemiology, and pathology, which suggest that it may in fact be caused by a number of closely related aetiological agents. See: espundia. Synonym: American leishmaniasis, leishmaniasis americana, nasopharyngeal leishmaniasis, New World leishmaniasis. (05 Mar 2000) |
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| Old World leishmaniasis | Infection with promastigotes (leptomonads) of Leishmania tropica and of leishmaniasis major inoculated into the skin by the bite of an infected sandfly, Phlebotomus (commonly P. Papatasi); it is endemic in parts of Asia Minor, northern Africa, and India, and is known by innumerable names, each indicating its locality (e.g., Aleppo, Baghdad, Delhi, or Jericho boil; Aden ulcer; Biskra button); the ulcer begins as a papule that enlarges to a nodule and then breaks down into an ulcer. Two distinctive clinical and epidemiological diseases are recognised, the more common and widespread zoonotic rural disease with a moist acute form, caused by L. Major, with reservoir rodent hosts; and an urban, anthroponotic, dry, chronic form of leishmaniasis caused by leishmaniasis tropica, without a reservoir host, and now largely controlled. See: zoonotic cutaneous leishmaniasis, anthroponotic cutaneous leishmaniasis. Synonym: juccuya, Old World leishmaniasis, tropical sore. (05 Mar 2000) |
| genetics, population | The study of the genetic composition of populations and of the effects of factors such as selection, population size, mutation, migration, and genetic drift on the frequencies of various genotypes and phenotypes. (12 Dec 1998) |
| growth rate of population | <epidemiology> A measure of population change in the absence of migration, comprising addition of newborns and subtraction of deaths; the result is known as the natural rate of increase of the population; it is the difference between the crude birth rate and the crude death rate. (05 Mar 2000) |
| rural population | The inhabitants of rural areas or of small towns classified as rural. (12 Dec 1998) |
| p in population genetics | The frequency of the more common of two different alternative (allelic) versions of a gene. (the frequency of less common allele is q). (12 Dec 1998) |
| population | 1. <genetics> A stable group of randomly interbreeding individuals. 2. <statistics> The set of objects or individuals from which a random sample is drawn. Origin: L. Populatio, from populus = people (18 Nov 1997) |
| population characteristics | <epidemiology> Qualities and characterization of various types of populations within a social or geographic group, with emphasis on demography, health status, and socioeconomic factors. (12 Dec 1998) |
| population control | Includes mechanisms or programs which control the numbers of individuals in a population of humans or animals. (12 Dec 1998) |
| population density | <epidemiology> Number of individuals in a population relative to space. (12 Dec 1998) |
| population diffusion coefficient | <cell biology> Coefficient that describes the tendency of a population of motile cells to diffuse through the environment. Its use presupposes that the cells move in a random walk. (18 Nov 1997) |
| population dynamics | <epidemiology> The pattern of any process, or the interrelationship of phenomena, which affects growth or change within a population. (12 Dec 1998) |
| population genetics | <epidemiology, genetics> The study of genetic influences on the components of cause and effect in the somatic characteristics of populations. (05 Mar 2000) |
| population growth | <epidemiology> Increase, over a specific period of time, in the number of individuals living in a country or region. (12 Dec 1998) |
| population pyramid | <epidemiology> Graphical representation of the age and sex composition of a population, constructed by computing the percentage distribution of the population in each age and sex class. (05 Mar 2000) |