A
Anemia: A reduction in the number of circulating
red blood cells or in the quantity of hemoglobin.
Anopheles: A genus of mosquito, some species of which can transmit
human malaria.
Anorexia: Lack of appetite, lack of desire or interest in food.
Anthropophilic: Anthropophilic mosquitoes are mosquitoes that prefer
to take blood meals on humans.
Antibiotic: Antimicrobial agent made from a mold or a bacterium
that kills or slows the growth of other microbes, specifically bacteria.
Example: penicillin.
Antibody: A specialized serum protein (immunoglobulin
or gamma globulin) produced by B lymphocytes in the blood in response
to an exposure to foreign proteins ("antigens"). The antibodies
specifically bind to the antigens that induced the immune response.
Antibodies help defend the body against infectious agents such as
bacteria, viruses or parasites.
Antigen: Any substance
that stimulates the immune system to produce antibodies. Antigens
are often foreign substances such as invading bacteria, viruses
or parasites.
Antimicrobial agents: The drugs, chemicals, or
other substances that kill or slow the growth of microbes. They include
antibacterial drugs (which kill bacteria), antiviral agents (which
kill viruses), antifungal agents (which kill fungi), and antiparasitic
drugs (which kill parasites).
Antimicrobial resistance: Antimicrobial resistance is the result
of microbes changing in ways that reduce or eliminate the effectiveness
of drugs, chemicals, or other agents to cure or prevent infections.
Aralen: A brand name for chloroquine phosphate.
Artemisinin: A drug used against malaria, derived from the Qinghao
plant, Artemisia annua L.
Atovaquone: A drug used against malaria. It is found in the combination
atovaquone-proguanil.
Autochthonous: Malaria transmitted by mosquitoes. Autochthonous
malaria can be indigenous (in a geographic area where malaria occurs
regularly) or introduced (in a geographic area where malaria does
not occur regularly).
B
Bacteria: (singular: Bacterium) Single-celled
organisms that are found throughout nature and can be beneficial
or cause disease.
B-cell (B-lymphocyte): White blood cells of the immune system that
are derived from the bone marrow and spleen. B cells develop into
plasma cells, which produce antibodies.
C
Carbamate: A chemical product used as an insecticide.
Cerebral malaria: A complication of Plasmodium
falciparum malaria
in which infected red blood cells obstruct blood circulation in
the small blood vessels in the brain. When cerebral malaria is present,
the disease is classified as severe malaria.
Chemoprophylaxis: Taking antimalarial drugs to
prevent the disease.
Chloroquine: A drug used against malaria. A very safe and inexpensive
drug, its value has been compromised by the emergence of chloroquine-resistant
malaria parasites.
Cinchonism: Side effects from quinine or quinidine. Includes tinnitus,
headache, nausea, diarrhea, altered auditory acuity, and blurred
vision.
The term derives from cinchona bark, the natural source of quinine.
Clindamycin: An antibiotic that can be used against malaria.
Clinical cure: Elimination of malaria symptoms, sometimes without
eliminating all parasites. See "radical cure" and "suppressive
cure/treatment."
Coma: A decreased state of consciousness from which a person cannot
be roused.
Congenital malaria: Malaria in a newborn or infant, transmitted
from the mother at birth.
Cryptic: A case of malaria where epidemiologic investigations fail to identify an apparent mode of acquisition (this term applies mainly to cases found in non-endemic countries).
D
DEET: N,N-diethylmetatoluamide, an ingredient
of insect repellents.
Defervescence: The reduction of a patient's abnormally elevated
temperature into the normal range.
Deltamethrin: An insecticide.
Diurnal: During the daytime.
Doxycycline: An antibiotic drug that can be used against malaria.
Drug resistance: Drug resistance is the result of microbes changing
in ways that reduce or eliminate the effectiveness of drugs, chemicals,
or other agents to cure or prevent infections.
Dyspnea: Shallow, labored breathing.
E
Efficacy: The power or capacity to produce a
desired effect.
ELISA: Enzyme-linked immunosorbent assay. ELISA is now often used
to determine whether mosquito salivary glands are positive for sporozoites.
Endemic: Where disease occurs on a consistent basis.
Endophagic: An endophagic mosquito is a mosquito
that feeds indoors.
Endophilic: An endophilic mosquito is a mosquito that tends to inhabit/rest
indoors. Endophilism facilitates the blocking of malaria transmission
through application of residual insecticides to walls.
Epidemic: The occurrence of more cases of disease than expected
in a given area or among a specific group of people over a particular
period of time.
Epidemiology: The study of the distribution and determinants of
health-related states or events in specified populations, and the
application of this study to the control of health problems.
Eradication: The process of removing something permanently.
Erythrocyte: A red blood cell.
Erythrocytic stage: A stage in the life cycle of the malaria parasite
found in the red blood cells. Erythrocytic stage parasites cause
the symptoms of malaria.
Etiology: The cause or origin of a disease or disorder; the study
of the factors that cause disease and of the method of their introduction
into the host.
Exoerythrocytic stage: A stage in the life cycle
of the malaria parasite found in liver cells (hepatocytes). Exoerythrocytic
stage parasites do not cause symptoms.
Exophagic: An exophagic mosquito is a mosquito that feeds outdoors.
Exophilic: An exophilic mosquito tends to inhabit/rest outdoors.
Residual insecticides in buildings are less effective at controlling
exophilic mosquitoes.
F
Falciparum: See Plasmodium.
Fansidar: Brand name of sulfadoxine-pyrimethamine, a drug used against
malaria.
G
G6PD deficiency: An inherited abnormality that
causes the loss of a red blood cell enzyme. People who are G6PD deficient
should not take the antimalarial drug primaquine.
Gametocyte: The sexual stage of malaria parasites. Male gametocytes
(microgametocytes) and female gametocytes (macrogametocytes) are
inside red blood cells in the circulation. If they are ingested
by a female Anopheles mosquito, they undergo sexual reproduction
which starts the extrinsic (sporogonic) cycle of the parasite in
the mosquito. Gametocytes of Plasmodium falciparum are typically
banana or crescent-shaped (from the latin falcis=sickle).
Gene: The basic unit of inheritance. A gene
is a segment of DNA that specifies the structure of a protein
or an RNA molecule.
Genetic diversity: The variety of different types of genes in a
species or population. Genetic diversity is really a form of biodiversity.
H
Halofantrine: A drug used against malaria in some
countries, but not recommended by CDC.
Hematocrit: The amount of blood consisting of red blood cells,
measured as a percentage.
Hematologic: Having to do with the blood.
Hemoglobin: The red, oxygen-carrying protein found in red blood
cells.
Hemolysis: Destruction of red blood cells. Malaria causes hemolysis
when the parasites rupture the red blood cells in which they have
grown.
Hepatocytes: Liver cells.
Hepatomegaly: Enlarged
liver.
Hypnozoite: Dormant form of malaria parasites found in liver cells.
Hypnozoites occur only with Plasmodium vivax and P. ovale. After
sporozoites (inoculated by the mosquito) invade liver cells, some
sporozoites develop into dormant forms (the hypnozoites), which
do not cause any symptoms. Hypnozoites can become activated months
or years after the initial infection, producing a relapse.
Hypoglycemia: Low blood glucose. Hypoglycemia can occur in malaria.
In addition, treatment with quinine and quinidine stimulate insulin
secretion, reducing blood glucose.
I
Icterus: See jaundice.
Immune system: The cells, tissues and organs that assist the body
to resist infection and disease by producing antibodies and/or cells
that inhibit the multiplication of the infectious agent.
Immunity: Protection generated by the body's immune system, in response
to previous malaria attacks, resulting in ability to control or
lessen a malaria attack.
Immunization: The process or procedure by which a subject (person,
animal, or plant) is rendered immune, or resistant to a specific
disease. This term is often used interchangeably with vaccination
or inoculation, although the act of inoculation does not always
result in immunity.
Imported malaria: Malaria acquired outside a specific geographic
area.
Incubation period: The interval of time between infection by a microorganism
and the onset of the illness or the first symptoms of the illness.
In malaria, the incubation is between the mosquito bite and the
first symptoms. Incubation periods range from 7 to 40 days, depending
on species.
Infection: The invasion of an organism by a pathogen such as bacteria,
viruses, or parasites. Some, but not all, infections lead to disease.
Indigenous malaria: Mosquito-borne transmission of malaria in a
geographic area where malaria occurs regularly.
Induced malaria: Malaria acquired through artificial means (e.g.
blood transfusion, shared needles or syringes, or malariotherapy).
Introduced malaria: Mosquito-borne transmission of malaria from
an imported case in a geographic area where malaria does not occur
regularly.
J
Jaundice: Yellow discoloration of skin and eyes
due to elevated blood levels of bilirubin.
K
L
Lariam: Brand name of mefloquine, a drug used
against malaria.
Larvae: Mosquito larvae are immature, wingless
forms that develop in water.
Leukocyte: White blood cell.
Leukocytosis: Increase in total white blood cell count.
Leukopenia: Decrease in total white blood cell count.
Lymphocyte: Leukocyte with a large round nucleus and usually a small
cytoplasm. Specialized types of lymphocytes have enlarged cytoplasms
and produce antibodies. Other specialized lymphocytes are important
in cellular immune responses.
M
Macrogametocyte: The female form of the gametocyte.
Malarone: Brand name of atovaquone-proguanil, a drug used against
malaria.
Malariae: See Plasmodium.
Merozoite: A daughter-cell formed by asexual development in the
life cycle of malaria parasites. Liver-stage and blood-stage malaria
parasites develop into schizonts which contain many merozoites.
When the schizonts are mature, they (and their host cells!) rupture;
the merozoites are released and infect red blood cells.
Mefloquine: A drug used against malaria.
Microgametocyte: The male form of the gametocyte.
Molecular methods: Methods that are based on identification and
characterization of certain molecules and gene sequences of a pathogen's
genetic makeup.
Monocyte: Leukocyte with a large, usually kidney-shaped nucleus.
Within tissues, monocytes develop into macrophages which ingest
bacteria, dead cells, and other debris.
O
Oocyst: A stage in the life cyle of malaria parasites, oocysts are
rounded cysts located in the outer wall of the stomach of mosquitoes.
Sporozoites develop inside the oocysts. When mature, the oocysts
rupture and release the sporozoites, which then migrate into
the mosquito's salivary glands, ready for injection into the
human host.
Ovale: See Plasmodium.
P
Parasite: Any organism that lives in or on another
organism without benefiting the host organism; commonly refers to
pathogens, most commonly in reference to protozoans and helminths.
Parasitemia: The presence of parasites in the blood. The term can
also be used to express the quantity of parasites in the blood (e.g., "a
parasitemia of 2%").
Paroxysm: A sudden attack or increase in intensity of a symptom,
usually occurring in intervals.
Pathogen: Bacteria, viruses, parasites or fungi can cause disease.
Permethrin: A pyrethroid insecticide.
Phagocyte: A type of white blood cell that can engulf and destroy
foreign organisms, cells and particles. Phagocytes are an important
part of the immune system.
Plasmodium: The genus of the parasite that causes malaria. The genus
includes four species that infect humans: Plasmodium falciparum,
Plasmodium vivax, Plasmodium ovale and Plasmodium
malariae.
Platelets: Small, irregularly-shaped bodies in
the blood that contain granules. These cells are important components
of the blood coagulation (clotting) system.
Polymorphic: Literally meaning having more than one form. In terms
of genes it means that there are several variants (alleles) of a
particular gene that occur simultaneously in a population.
Presumptive treatment: Treatment of clinically
suspected cases without, or prior to, results from confirmatory laboratory
tests.
Primaquine: A drug used against malaria.
Proguanil: A drug used against malaria.
Prophylaxis: See "chemoprophylaxis."
Protozoan: Single-celled organism that can perform all necessary
functions of metabolism and reproduction. Some protozoa are free-living,
while others, including malaria parasites, parasitize other organisms
for their nutrients and life cycle.
Pyrethroid: A class of insecticides derived from
the natural pyrethrins.
Q
Quinine: A drug used against malaria, obtained
from the bark of the cinchona tree.
R
Radical cure: (also: radical treatment) Complete
elimination of malaria parasites from the body; the term applies
specifically to elimination of dormant liver stage parasites
(hypnozoites) found in Plasmodium vivax and P. ovale.
Recrudescence: A repeated attack of malaria (short term relapse
or delayed), due to the survival of malaria parasites in red blood
cells.
Radical treatment: see radical cure.
Relapse: Recurrence of disease after it has been
apparently cured. In malaria, true relapses are caused by reactivation
of dormant liver stage parasites (hypnozoites) found in Plasmodium
vivax and P. ovale.
Residual insecticide spraying: Treatment of houses where people
spend night-time hours, by spraying insecticides that have residual
efficacy (i.e., that continue to affect mosquitoes for several months).
Residual insecticide spraying aims to kills mosquitoes when they
come to rest on the walls, usually after a blood meal.
Resistance: The ability of an organism to develop strains that are
impervious to specific threats to their existence. The malaria parasite
has developed strains that are resistant to drugs such as chloroquine.
The Anopheles mosquito has developed strains that are resistant
to DDT and other insecticides.
Rigor: Severe shaking chill.
S
Schizogony: Asexual reproductive stage of malaria
parasites. In red blood cells, schizogony entails development
of a single trophozoite into numerous merozoites. A similar process
happens in infected liver cells.
Schizont: A developmental form of the malaria parasite that contains
many merozoites. Schizonts are seen in the liver-stage and blood-stage
parasites.
Sequelae: Morbid conditions following as a consequence of a disease.
Serology: The branch of science dealing with the measurement and
characterization of antibodies and other immunological substances
in body fluids, particularly serum.
Species: Organisms in the same genus that have similar characteristics.
Splenectomy: Removal of the spleen.
Splenomegaly: Enlargement
of the spleen. Found in some malaria patients. Splenomegaly can
be used to measure malaria endemicity during surveys (e.g., in
communities or in schoolchildren).
Sporozoite: A stage in the life cycle of the malaria parasite. Sporozoites
are produced in the mosquito and migrate to the mosquito's salivary
glands. They can be inoculated into a human host when the mosquito
takes a blood meal on the human. In the human, the sporozoites enter
liver cells where they develop into the next stage of the malaria
parasite life cycle (the liver stage or exo-erythrocytic stage).
Sporozoite rate: The proportion of female anopheline mosquitoes
of a particular species that have sporozoites in their salivary
glands (as seen by dissection), or that are positive in immunologic
tests to detect sporozoite antigens.
Strain: A genetic variant within a species.
Sulfadoxine-pyrimethamine: A
drug used against malaria.
Suppressive treatment: Treatment intended to prevent clinical symptoms
and parasitemia through destruction of parasites in red blood cells.
It does not prevent infection because the parasite stages inoculated
by the mosquito (sporozoites) will survive and invade the liver
with the development of liver-stage parasites. It is when the parasites
leave the liver cells to invade the blood that they are eliminated.
Because the blood- stage parasites are the ones that cause disease,
eliminating these stages will prevent symptoms.
T
Tachycardia:Increased heart rate.
Tachypnea: Increased rate of breathing.
Tetracycline: See doxycycline. An antibiotic drug
that can be used against malaria.
Thrombocytopenia: Low platelet count, that can lead to impaired
blood clotting and spontaneous bleeding. Thrombocytopenia can occur
in severe Plasmodium falciparum malaria.
Tinnitus: Ringing sound in the ears, a common side effect of quinine
treatment.
Trophozoite: A developmental form during the blood stage of malaria
parasites. After merozoites have invaded the red blood cell, they
develop into trophozoites (sometimes, early trophozoites are called "rings" or "ring
stage parasites"); trophozoites develop into schizonts.
V
Vaccine: A preparation that stimulates an immune
response that can prevent an infection or create resistance to
an infection.
Vector: An organism (e.g., Anopheles mosquitoes) that transmits
an infectious agent (e.g. malaria parasites) from one host to the
other (e.g., humans).
Vector competence: The ability of a vector (e.g., Anopheles mosquitoes)
to transmit a disease (e.g., malaria).
Virus: A microorganism composed of a piece of genetic
material - RNA or DNA - surrounded by a protein coat. To replicate,
a virus must infect a cell and direct its cellular machinery to
produce new viruses.
Vivax: See Plasmodium
Z
Zoophilic: Zoophilic mosquitoes are mosquitoes
that prefer to take blood meals on animals.
Page last modified : June
3,
2004
Content source: Division of Parasitic Diseases
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)
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