Navy Medical Department Guide to Malaria Prevention and Control

Appendix 6: Glossary

Department of the Navy
Bureau of Medicine and Surgery

anemia - decrease in number of red blood cells and/or quantity of hemoglobin. Malaria causes anemia through rupture of red blood cells during merozoite release.

anorexia - lack of appetite, lack of desire or interest in food.

arthralgia - pain or aching of the joints.

chemoprophylaxis - method of disease prevention by taking specific medications. Malaria chemoprophylaxis requires drugs to be taken before, during, and after exposure. Very effective, but not absolute because of drug resistance and poor compliance. Chemoprophylaxis is also called "suppressive treatment."

cinchonism -side effects from quinine or quinidine, reversible with lower dosages or termination of the drugs. Effects include tinnitus, headache, nausea, diarrhea, altered auditory acuity, and blurred vision. The term derives from cinchona bark, the natural source of quinine.

clinical cure - elimination of malaria symptoms, sometimes without eliminating all parasites. See "radical cure" and "suppressive cure."

coma - decreased state of consciousness from which a person cannot be aroused. See "Glasglow coma scale," Table 4-5 in Chapter 4, page 46.

cure - see "clinical cure," "radical cure," and "suppressive cure."

cyanosis, cyanotic -physical sign where the skin appears blue, caused by lack of oxygen.

delirious - mental state characterized by confusion and agitation. Delusions and hallucinations may also be present.

D.O.T. (directly observed therapy) - most effective method of ensuring drug compliance, where drug administration is observed by an appointed authority.

dyspnea -shallow, labored breathing.

eosinophilia - an increased number of eosinophils, a type of white blood cell. Greater than normal numbers of eosinophils are often associated with parasitic infections, but not malaria.

erythrocyte -a red blood cell.

erythrocytic stage - the malaria parasite's life cycle when infecting and developing within red blood cells.

exoerythrocytic stage - stage in plasmodia life cycle when developing in liver cells (hepatocytes).

fever paroxysm - see "paroxysm."

fluid overload -a condition in which an excessive amount of IV fluids (crystalloids, blood products) has been administered. In severe episodes causes pulmonary edema.

fluid resuscitation - administration of IV fluids to correct a loss or decrease in blood volume. The loss may be actual, relative, or both. Actual loss of blood volume is due to hemorrhage, sweating, or diarrhea. Relative loss of blood volume occurs when the vascular system dilates, increasing total volume. Fluid resuscitation is done with a variety of IV fluids, such as normal saline, lactated ringers, dextrose solutions, and blood products.

flush - capillary dilation causing skin to appear reddish in color.

gametocyte - sexual stage of malaria parasites which form in red blood cells. Macrogametocytes (female) and microgametocytes (male) form in individual erythrocytes, are ingested by female mosquitoes, and unite in the mosquito's stomach. Characteristic diagnostic features of P. falciparum gametocytes include their crescent or banana shape, and their overshadowing of the morphology of infected red blood cells.

hematemesis - vomiting of blood which may be either acute and bright red; or old and clotted appearing as coffee grounds.

hematochezia - passing blood rectally; blood may appear bright red, or dark red-black, and is usually foul smelling and sticky.

hematocrit - the amount of blood consisting of red blood cells, measured as a percentage. Measured after a blood sample has been centrifuged or allowed to settle. Normal hematocrit values: Males 39-49%; females 33-43%.

hemoglobin -the protein in red blood cells which carries oxygen. Normal range of hemoglobin values: Males - 13.6 - 17.2 g/dl; Females -12.0 -15.0 g/dl (136-173 g/L and 120-150 g/L).

hemolysis - destruction of red blood cells. Malaria causes hemolysis when malaria parasites mature and rupture red blood cells they infected.

hepatocytes - liver cells.

hepatomegaly - enlarged liver. An unusual physical finding in malaria.

hyperpyrexia - high fever greater than 105º F (40.5º C).

hyperthermic - elevated temperature.

hypnozoite - a stage of malaria parasites found in liver cells. After sporozoites invade liver cells, some develop into latent forms called hypnozoites. They become active months or years later, producing a recurrent malaria attack. Only P. vivax and P. ovale species that infect humans develop latent stage hypnozoites. Primaquine is the only available drug active against hypnozoites.

hypoglycemia -blood glucose less than the lower value of normal (70-110 mg/dl [3.9-6.1 mmol/L in SI reference units]). Glucose levels of 40 and below constitute severe hypoglycemia, a life-threatening emergency. Hypoglycemia is common in malaria, as malaria parasitized red blood cells utilize glucose 75 times faster than uninfected cells. In addition, treatment with quinine and quinidine stimulate insulin secretion, reducing blood glucose.

hyponatremia - serum sodium less than the normal lower limit, which is 135-147 mEq/L (135-147 mmol/L in SI reference units). Serum sodium levels approaching 120 and below constitute severe hyponatremia, a medical emergency. Hyponatremia can be seen in malaria, and is indicative of complicated malaria.

hypotension -see "orthostatic hypotension."

icterus -yellow discoloration of the eyes due to an elevated bilirubin. Faint discoloration is seen when bilirubin blood levels rise to 2.5-3.0 mg/dl (43-51 mmol/L in SI reference units). Often identified as scleral icterus, because the sclera or "whites" of the eyes turn yellow.

immunity - the body's ability to control or lessen a malaria attack with antibodies and other protective reactions developed in response to previous malaria attacks. Semi-immune individuals live in malaria endemic areas and are repeatedly infected. Immunity developed does not prevent or cure malaria attacks, but controls the attack, minimizing symptoms. Such individuals typically have low blood levels of malaria parasites.

incubation period - time period beginning when malaria parasites are injected by a mosquito bite, ending when symptoms develop. Incubation periods range from 7 to 40 days, depending on species.

jaundice - yellow discoloration of skin and eyes due to elevated blood levels of bilirubin.

leukocytosis - total white blood cell count greater than 11,000 per cubic millimeter. Leukocytosis refers specifically to elevation in the number of polymorphonuclear leukocytes, which make up the majority of white blood cells.

leukopenia -total white blood cell count of less than 5,000 per cubic millimeter. Leukopenia refers specifically to a reduction in the number of polymorphonuclear leukocytes, which make up the majority of white blood cells.

lymphadenopathy - enlarged lymph nodes, which can be detected by physical examination. Lymphadenopathy is not a usual physical finding in malaria.

malaise - subjective feeling of being sick, ill, or not healthy. The feeling is generalized, varying from mild to severe in intensity. It may be the lone clinical manifestation of malaria, or may accompany other signs and symptoms.

merozoite - the end product of the asexual reproductive stage (schizogony) of the malaria parasite life cycle. Merozoite maturation takes place in erythrocytes or hepatocytes. Schizogony in erythrocytes ends in their rupture, releasing merozoites which infect other red blood cells. Schizogony in liver cells culminates in their rupture and merozoite release, which infect red blood cells. In P. vivax and P. ovale infections, released merozoites can also infect other liver cells and develop into hypnozoites.

myalgia -muscle pain or ache.

obtunded -mental state in which reaction to stimuli is dulled or blunted, such as persons with severe alcohol intoxication.

oliguria - decrease of urine production.

oocyst -cysts located in the outer stomach wall of mosquitoes, where sporozoite development takes place. When mature, the oocysts rupture and release sporozoites. Sporozoites subsequently migrate to salivary glands, and get injected into the host when mosquitoes feed.

orthostatic hypotension - decrease in blood pressure occurring when an individual arises from a seated or lying position. A small decrease in blood pressure is normal, but large decreases are abnormal, especially if accompanied by clinical manifestations such as faintness, light-headedness, dizziness, or increased pulse. Orthostatic hypotension is a common finding in patients with malaria infections.

parasitemia - level of malaria parasites in blood. If no fever or other symptoms except for an enlarged spleen accompany finding of malaria parasites in blood, the condition is referred to as "asymptomatic parasitemia."

paroxysm - a sudden attack or increase in intensity of a symptom, usually occurring in intervals. Malaria is classically described as producing fever paroxysms; sudden severe temperature elevations accompanied by profuse sweating. However, fever paroxysms are rarely exhibited in the majority of malaria cases in non-immune persons, while semi-immune local inhabitants are more likely to have them. Therefore, diagnosis should not be based on this finding in U.S. military personnel.

petechiae - small red or purple skin macules, usually 1-3 mm in diameter. They are manifestations of small subcutaneous bleeds and seen in minor trauma, when the platelet count is very low, or in clotting defects. They are also caused by immune complex deposits in the skin.

petechial rash -grouping of petechiae.

presumptive treatment - administration of anti-malarial drugs in suspected cases before results of laboratory tests are available to confirm diagnosis.

prophylaxis - see "chemoprophylaxis."

prostration - a state characterized by an extreme loss of strength.

pulmonary edema - accumulation of fluid in lung alveoli due to leakage, resulting in difficulty breathing. It is generally due to breakdown of stability of membranes lining alveolar spaces and/or fluid overload.

QT interval - measured from the beginning of the QRS to the end of the T wave, it represents total duration of ventricular systole. As a rule of thumb, it should be less than 50% of the preceding R-R interval. A prolonged QT interval indicates delayed repolarization of ventricular myocardium. Development of serious ventricular tachyarrhythmias (R on T phenomenon), syncope, and sudden death are possible under this condition.

radical treatment - treatment intended to achieve cure of P. vivax or P. ovale malaria. Requires primaquine treatment, which destroys latent exoerythrocytic stage parasites (hypnozoites).

radical cure - complete elimination of malaria parasites from the body, specifically hypnozoites.

rales -crackling sounds heard at end inspiration during lung auscultation. An abnormal physical finding.

RBC -red blood cell.

recrudescence -a repeated attack of malaria (short term relapse or delayed), due to the survival of malaria parasites in red blood cells. Characteristic of P. malariae infections.

recurrence -a repeated attack weeks, months, or sometimes years, after initial malaria infection, also called a long-term relapse. Due to re-infection of red blood cells from malaria parasites (hypnozoites) that persisted in liver cells (hepatocytes).

relapse - a repeat attack of malaria.

resuscitation -see "fluid resuscitation."

rigor - severe chill, characterized by shaking of the body.

sallow - pale, reddish-yellow in color.

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.

scleral icterus - see "icterus."

splenomegaly - an enlarged spleen. A common finding in malaria patients that sometimes can be detected by physical examination.

sporozoite -stage of malaria parasites injected into the bloodstream by biting infective mosquitoes. Sporozoites infect liver cells, disappearing from bloodstream within 30 minutes.

stuporous - mental state characterized by lack of awareness of one's surroundings.

suppressive treatment -treatment intended to prevent clinical symptoms or parasitemia through destruction of parasites in red blood cells. It does not prevent or eliminate malaria infection as parasites may persist in the liver and produce a relapse after drug therapy is stopped. Suppressive treatment is also called "chemoprophylaxis."

tachycardia - increased heart rate, defined as greater than 100 beats per minute.

tachypnea - increased respiratory rate defined as greater than 20 breaths per minute.

thrombocytopenia - low platelet count, defined as less than 150,000. Low platelet counts can lead to impaired blood clotting, and counts below 50,000 increase the risk of spontaneous bleeding. Thrombocytopenia is typical in malaria, though spontaneous bleeding is rare.

tinnitus - ringing sound in the ears, a common side effect of quinine treatment.

treatment - see "presumptive treatment," "radical treatment," and "suppressive treatment."

trophozoite - early developmental stage of blood schizont.

urticaria -hives. Numerous swellings in skin, ranging from many localized lesions a few mm to a few cm in diameter, to large blotchy irregular swellings.

vasodilation - increase in diameter of small vessels of the vascular system. Net result is often a decrease in blood pressure, which may be significant.

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Operational Medicine 2001

Health Care in Military Settings

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