Malaria
Malaria: Excerpt from Professional Guide to Diseases (Eighth Edition)
Malaria, an acute infectious disease, is caused by protozoa of the genus Plasmodium: P. falciparum, P. vivax, P. malariae, and P. ovale, all of which are transmitted to humans by mosquito vectors. Falciparum malaria is the most severe form of the disease. When treated, malaria is rarely fatal; untreated, it's fatal in 10% of victims, usually as a result of complications such as disseminated intravascular coagulation (DIC).
Untreated primary attacks last from a week to a month, or longer. Relapses are common and can recur sporadically for several years. Susceptibility to the disease is universal.
Causes and incidence
Malaria literally means “bad air” and for centuries was thought to result from the inhalation of swamp vapors. It's now known that malaria is transmitted by the bite of female Anopheles mosquitoes, which abound in humid, swampy areas. When an infected mosquito bites, it injects Plasmodium sporozoites into the wound. The infective sporozoites migrate by blood circulation to parenchymal cells of the liver; there they form cystlike structures containing thousands of merozoites.
Upon release, each merozoite invades an erythrocyte and feeds on hemoglobin. Eventually, the erythrocyte ruptures, releasing heme (malaria pigment), cell debris, and more merozoites, which, unless destroyed by phagocytes, enter other erythrocytes. (See What happens in malaria, page 262.) At this point, the infected person becomes a reservoir of malaria who infects any mosquito that feeds on him, thus beginning a new cycle of transmission.Hepatic parasites (P. vivax, P. ovale, and P. malariae) may persist for years in the liver. These parasites are responsible for the chronic carrier state. Because blood transfusions and street-drug paraphernalia can also spread malaria, drug addicts have a higher incidence of the disease. Malaria is a worldwide health problem that continues to impede the development of many countries.
Malaria is a tropical and subtropical disease. It's most prevalent in Asia, Africa, and Latin America. The Centers for Disease Control and Prevention (CDC) estimates 300 to 500 million cases occur each year, with more than 1 million resulting in death. It's the greatest disease hazard for travelers in warm climates.
Signs and symptoms
After an incubation period of 12 to 30 days, malaria produces chills, fever, headache, and myalgia, interspersed with periods of well-being (the hallmark of the benign form of malaria). Acute attacks (paroxysms) occur when erythrocytes rupture. There are three stages:
❑cold stage, lasting 1 to 2 hours, ranging from chills to extreme shaking
❑hot stage, lasting 3 to 4 hours, characterized by a high fever (up to 107° F [41.7° C])
❑wet stage, lasting 2 to 4 hours and characterized by profuse sweating.
Paroxysms occur every 48 to 72 hours when malaria is caused by P. malariae and every 42 to 50 hours when malaria is caused by P. vivax or P. ovale. All three types have low levels of parasitosis and are self-limiting as a result of early acquired immunity.
P. vivax and P. ovale also produce hepatosplenomegaly. Hemolytic anemia is present in all but the mildest infections.
The most severe and only life-threatening form of malaria is caused by P. falciparum. This species produces persistent high fever, orthostatic hypotension, and red blood cell (RBC) sludging that leads to capillary obstruction at various sites. Signs and symptoms of obstruction include:
❑cerebral — hemiplegia, seizures, delirium, and coma
❑pulmonary — coughing and hemoptysis
❑splanchnic — vomiting, abdominal pain, diarrhea, and melena
❑renal — oliguria, anuria, and uremia.
During blackwater fever (a complication of P. falciparum infection), massive intra-vascular hemolysis causes jaundice, hemoglobinuria, a tender and enlarged spleen, acute renal failure, and uremia. This complication is fatal in about 20% of patients.
Diagnosis
CONFIRMING DIAGNOSIS A history showing travel to endemic areas, recent blood transfusion, or drug abuse in a person with high fever of unknown origin strongly suggests malaria. However, because symptoms of malaria mimic other diseases, unequivocal diagnosis depends on laboratory identification of the parasites in RBCs of peripheral blood smears.
The CDC can identify donors responsible for transfusion malaria through indirect fluorescent serum antibody tests. These tests are unreliable in the acute phase because antibodies can be undetectable for 2 weeks after onset.
Supplementary laboratory values that support this diagnosis include decreased hemoglobin levels, normal to decreased leukocyte count (as low as 3,000/µl), and protein and leukocytes in urine sediment. In falciparum malaria, serum values reflect DIC: reduced number of platelets (20,000 to 50,000/µl); prolonged prothrombin time (18 to 20 seconds); prolonged partial thromboplastin time (60 to 100 seconds); and decreased plasma fibrinogen.
Treatment
Malaria is best treated with oral chloroquine in all forms except chloroquine-resistant P. falciparum. Symptoms and parasitemia decrease within 24 hours after such therapy begins, and the patient usually recovers within 3 to 4 days. If the patient is comatose or vomiting frequently, chloroquine is given I.M.
Malaria caused by P. falciparum, which is resistant to chloroquine, requires treatment with oral quinine given concurrently with pyrimethamine and a sulfonamide such as sulfadiazine. Mefloquine can also be used for resistant P. falciparum. Relapses require the same treatment, or quinine alone, followed by tetracycline.
The only drug effective against the hepatic stage of the disease that’s available in the United States is primaquine. This drug can induce hemolytic anemia, especially in patients with glucose-6-phosphate dehydrogenase deficiency. (See Special considerations for antimalarial drugs, page 263.)
For travelers spending less than 3 weeks in areas where malaria exists, weekly prophylaxis includes oral chloroquine beginning 2 weeks before the trip and ending 6 weeks after it. (See How to prevent malaria.) Any traveler who develops an acute febrile illness should seek prompt medical attention, regardless of the prophylaxis taken.
Special considerations
❑Obtain a detailed patient history, noting any recent travel, foreign residence, blood transfusion, or drug addiction. Record symptom pattern, fever, type of malaria, and any systemic signs.
❑Assess the patient on admission and daily thereafter for fatigue, fever, orthostatic hypotension, disorientation, myalgia, and arthralgia. Enforce bed rest during periods of acute illness.
❑Protect the patient from secondary bacterial infection by following proper hand-hygiene and sterile techniques.
❑Protect yourself by wearing gloves when handling blood or body fluids.
❑Activate safety devices, and use safety syringes in practice.
❑Discard needles and syringes in an impervious container designated for incineration.
❑Handle bed linens according to standard precautions.
❑To reduce fever, administer antipyretics as ordered. Document onset, duration, and symptoms before and after episodes.
❑Fluid balance is fragile, so keep a strict record of intake and output. Monitor I.V. fluids closely. Avoid fluid overload (especially in P. falciparum), because it can lead to pulmonary edema and aggravate cerebral symptoms. Observe blood chemistry levels for hyponatremia and increased blood urea nitrogen, creatinine, and bilirubin levels. Monitor urine output hourly, and maintain it at 40 to 60 ml/hour for an adult and at 15 to 30 ml/hour for a child. Immediately report any decrease in urine output or the onset of hematuria as a possible sign of renal failure; be prepared to perform peritoneal dialysis for uremia caused by renal failure.
❑Slowly administer packed RBCs or whole blood while checking for crackles, tachycardia, and shortness of breath.
❑If humidified oxygen is ordered, note the patient's response, particularly any changes in rate or character of respirations, or any improvement in mucous membrane color.
❑Watch for and immediately report signs of internal bleeding, such as tachycardia, hypotension, and pallor.
❑Encourage frequent coughing and deep breathing, especially if the patient is on bed rest or has pulmonary complications. Record the amount and color of sputum.
❑Watch for adverse effects of drug therapy, and take measures to relieve them.
❑If the patient is comatose, make frequent, gentle changes in his position, and give passive range-of-motion exercises every 3 to 4 hours. If the patient is unconscious or disoriented, use restraints as needed, and keep an airway available as appropriate.
❑Provide emotional support and reassurance, especially in critical illness. Explain the procedures and treatment to the patient and his family. Suggest that other family members be tested for malaria. Emphasize the need for follow-up care to check the effectiveness of treatment and to manage residual problems.
❑Report all cases of malaria to local public health authorities.
Pictures
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
More About Malaria
More Medical Textbooks Online about Malaria
Review other book chapters online related to Malaria:
Medical Books Excerpts
- Fever
- "In a Page: Signs and Symptoms" (2004)
- [ read ]
- FEVER
- "Differential Diagnosis in Primary Care" (2007)
- [ read ]
- Fever
- "Handbook of Signs & Symptoms (Third Edition)" (2006)
- [ read ]
- Malaria
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Lassa fever
- "Professional Guide to Diseases (Eighth Edition)" (2005)
- [ read ]
- Fever
- "The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter" (2000)
- [ read ]
- Fever
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
- [ read ]
- Fever
- "Signs & Symptoms: A 2-in-1 Reference for Nurses" (2007)
- [ read ]
- Fever
- "The Diagnostic Approach to Symptoms and Signs in Pediatrics" (2006)
- [ read ]
- FEVER
- "Differential Diagnosis in Primary Care" (2007)
- [ read ]
- Malaria
- "The 5-Minute Pediatric Consult" (2008)
- [ read ]
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
» Next page:
Colorado tick fever (Professional Guide to Diseases (Eighth Edition))
Rate This Website
What do you think about the features of this website?
Take our user survey and have your say:
Website User Survey
Medical Tools & Articles:
Next articles:
Tools & Services:
Medical Articles:
Forums & Message Boards
- Ask or answer a question at the Boards:
