Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

Anopheles: a genus of mosquito, some species of which can transmit human malaria.1
Apicoplast: An organelle that is present in malaria parasites and is thought to be a relic of the chloroplast. It contains DNA which codes for ~30 plant-like proteins and bacteria-like ribosomes. A further 500 nuclear-encoded proteins of unknown phylogenetic origin are predicted to be targeted to this organelle. 7
Artemisinin: a drug used against malaria, derived from the Qinghao plant Artemisia annua.1
Artemisinin-based combination therapy (ACT): A treatment regimen for malaria, usually comprising two medicines, one of which is artemisinin or one of its derivatives. ACTs come in two varieties: co-packaged or the preferred co-formulated. 7
Assay: a procedure for measuring the biological or immunological activity of (a sample).4

B

Bacteria: (singular: bacterium) Single-celled organisms that are found throughout nature and can be beneficial or cause disease.1

C

Causal prophylactic activity: Effect of antimalarial drugs that prevent sporozoite infection or replication of parasites in the liver, in contrast to suppressive prophylaxis in which replication of parasites in the blood is prevented.7
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.1
Clinical development: (as of a drug) step in drug development where on the basis of pre-clinical toxicology and animal study data, a compound developer applies for IND (investigational new drug) status from the FDA (in US) or equivalent elsewhere in order to obtain right to test drugs on humans.3 Next step: see Phase I
Clinical trials: are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people. Trials are in four phases: Phase I tests a new drug or treatment in a small group; Phase II expands the study to a larger group of people; Phase III expands the study to an even larger group of people; and Phase IV takes place after the drug or treatment has been licensed and marketed. 5
Congenital malaria: Malaria in a newborn or infant, transmitted from the mother at birth.1

D

Dose-ranging study: A clinical trial in which two or more doses of an agent (such as a drug) are tested against each other to determine which dose works best and is least harmful. 5
Drug: a substance intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease. 2
Drug discovery process: Main steps include: identification of disease target that accounts for symptoms (target identification); target validation - evaluation of whether eliminating the target will lead to a modification of the progression of the disease to the benefit of patients; screening of compound libraries either by computer modelling (in silico) to see which molecules fit into the structure of the target or biologically, using high-throughput screening; lead identification - identification of a series of compounds whose chemical structures appear to have greatest impact on the target; lead optimization- identification a subset of more promising compounds, using chemistry and/or computing, on the basis of their apparent efficacy and safety; selection of candidates for preclinical and clinical development.3 Next step, see Preclinical development
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.1

E

Efficacy: (of a drug or treatment) the maximum ability of a drug or treatment to produce a result regardless of dosage. A drug passes efficacy trials if it is effective at the dose tested and against the illness for which it is prescribed. For example, in the procedure mandated by the FDA, Phase II clinical trials gauge efficacy, and Phase III trials confirm it. 5
Elimination: Malaria elimination, which might apply to a country or region, describes the situation in which all local transmission of malaria has ceased; cases of malaria might continue to occur but only as a result of the introduction of infections acquired elsewhere.6
Endemic: where disease occurs on a consistent basis.1
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.1
Epidemiology: the branch of medicine that deals with the incidence, distribution and possible control of disease and other factors relating to health.4
Eradication: The process of removing something permanently, such as a disease from a certain area.1 Malaria eradication describes the situation in which malaria parasites have disappeared from the globe, with the possible exception of specimens held in a secure laboratory. Eradication can refer to all human malaria parasites or to a single species. The eradication of P. falciparum is likely to be easier to achieve than eradication of P. vivax or P. ovale.6
Erythrocyte: A red blood cell.1
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.1

F

Fever clearance time: The time taken for body temperature to return to normal levels after the first dose of an antimalarial has been given. 7

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. 1
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). 1

H

High-throughput screening: process by which robotics are used to test the reactions of thousands of assays of different compounds against a target.3
Hypnozoite: The dormant liver stageof P. vivax and P. ovale. The parasite remains in hepatocytes after the other liver-stage parasites have replicated and released their merozoites. Hypnozoites are the source of malaria relapses 7

I

ICH: International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use, which issues guidelines for good laboratory and clinical practice. 7
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.1
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.1
in silico: modeling research conducted by means of computer simulation.3
Investigational new drug (IND): A new drug, antibiotic drug, or biological drug that is used in a clinical investigation. It also includes a biological product used in vitro for diagnostic purposes. 5
in vitro: (of processes or reactions) taking place in a test tube, culture dish or elsewhere outside a living organism.4
in vivo: (of processes) taking place in a living organism.4
Intermittent preventive treatment: Intermittent preventive treatment (IPT) describes the administration of an antimalarial drug or drug combination at specified times, often corresponding to the time when a subject has access to health services, to individuals at risk, whether or not they are infected. It is accepted that blood concentrations will fall below inhibitory concentrations between drug administrations.6

J

Jaundice: Yellow discoloration of skin and eyes due to elevated blood levels of bilirubin. 1 Jaundice is one of the clinical manifestations of malaria.

M

Malaria control: Effective malaria control is used to describe the situation in which malaria is no longer a considerable cause of deaths or illness but in which it continues to be transmitted.6
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.1

N

New Drug Application (NDA): An application submitted by the manufacturer of a drug to the FDA [or other regulatory authority] - after clinical trials have been completed - for a license to market the drug for a specified indication. 5

O

Oocyst: A stage in the life cycle 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.1

P

Parasite: Any organism that lives in or on another organism without benefiting the host organism.1
Parasite clearance time: The time taken for asexual parasites to no longer be detectable microscopically after the first dose of an antimalarial has been given.7
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%").1
Pharmacokinetics: the branch of pharmacology concerned with the movement of drugs within the body;4 the processes (in a living organism) of absorption, distribution, metabolism, and excretion of a drug or vaccine.5
Phase I trials: Initial studies to determine the metabolism and pharmacologic actions of drugs in humans, the side effects associated with increasing doses, and to gain early evidence of effectiveness; may include healthy participants and/or patients.5
Phase II trials: Controlled clinical studies conducted to evaluate the effectiveness of the drug for a particular indication or indications in patients with the disease or condition under study and to determine the common short-term side effects and risks.5
Phase III trials: Expanded controlled and uncontrolled trials after preliminary evidence suggesting effectiveness of the drug has been obtained, and are intended to gather additional information to evaluate the overall benefit-risk relationship of the drug and provide and adequate basis for physician labeling.5
Phase IV trials: Post-marketing studies to delineate additional information including the drug’s risks, benefits, and optimal use.5
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.1
Preclinical development: Refers to the testing of experimental drugs in the test tube or in animals - the testing that occurs before trials in humans may be carried out.5 Next step, see Clinical development
Protocol: A study plan on which all clinical trials for a particular drug are based. The plan is carefully designed to safeguard the health of the participants as well as answer specific research questions. A protocol describes what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and the length of the study. While in a clinical trial, participants following a protocol are seen regularly by the research staff to monitor their health and to determine the safety and effectiveness of their treatment.5

Q

Quinine: A drug used against malaria, obtained from the bark of the cinchona tree.1

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 P. vivax and P. ovale. Unless this takes place, patients will relapse.1
Recrudescence: A repeated attack of malaria (short term relapse or delayed), due to the survival of malaria parasites in red blood cells.1
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 P. vivax and P. ovale.1
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.1
Reticulocyte: An immature red blood cell 7

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.1
Schizont: A developmental form of the malaria parasite that contains many merozoites. Schizonts are seen in the liver-stage and blood-stage parasites.1
Sequelae: Morbid conditions following as a consequence of a disease.1
Side effects: Any undesired actions or effects of a drug or treatment. Negative or adverse effects may include headache, nausea, hair loss, skin irritation, or other physical problems. Experimental drugs must be evaluated for both immediate and long-term side effect.5
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).1
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).1

T

Toxicity: An adverse effect produced by a drug that is detrimental to the participant’s health. The level of toxicity associated with a drug will vary depending on the condition which the drug is used to treat.5
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.1

U

Uncomplicated malaria: Uncomplicated malaria describes the illness that is caused by the malaria parasite and is characterised by fever and other general symptoms but is not complicated by features of damage to organs, such as the brain, kidney or lung, which threatens the life of the patient.6

V

Vaccine: A preparation that stimulates an immune response that can prevent an infection or create resistance to an infection.1
Vector: An organism (e.g., Anopheles mosquito) that transmits an infectious agent (e.g. malaria parasite) from one host to the other (e.g., from mosquito to human).1
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.1

 


 

References

1http://www.cdc.gov/malaria/glossary.html

2Merriam Webster’s Medical Dictionary, 1995

3Kettler, H. and A. Towse. 2002. Public Private Partnerships for Research and Development: Medicines and Vaccines for Diseases of Poverty. London: Office of Health Economics, Appendix 5.

4The New Oxford Dictionary of English, 1998.

5http://www.clinicaltrials.gov/ct2/info/glossary, National Library of Medicine, USA (http://nlm.nih.gov/)

6Greenwood, B.M. "Control to elimination: implications for malaria research," Trends in Parasitology 24, Issue 10 (2008): 449-454.

7Wells, T.N.C., Alonso P.L., Gutteridge, W.E. "New medicines to improve control and contribute to the eradication of malaria," Nature Reviews Drug Discovery November 2009 Volume 8, Number 11, pp 879-891