Dengue and malaria are both mosquito borne fevers. Both are tropical illnesses. Both diseases feature fever, malaise, lethargy, body ache and headache. Dengue febrile phase lasts three days while malaria has a three day recurrent fever.
Dengue is a viral disease. Dengue is caused by RNA flavivirus that has four subtypes. Infection with one does not render the body immune to the other three. This virus goes from patient to patient inside Aedes mosquitoes.
Dengue symptoms are fever, joint pain, muscle pain, skin reddening, pin-point bleeding patches, conjunctival redness, and abdominal pain. Fever starts about three days after infection. The fever usually subsides after two to three days. This time period is called the febrile phase of dengue. Then the critical phase of dengue starts. The hallmark of dengue is fluid leakage from blood vessels. Gradual leakage of plasma from capillaries result in low blood pressure (hypotension), low pulse pressure, poor renal perfusion, poor urine output, fluid collection in the pleural cavity (effusion) and peritoneal cavity (ascites). Critical phase lasts for forty eight hours.
Full blood count shows the progression of leakage. Packed cell volume, platelet count, and white cell count are important parameters in the investigation of dengue. Platelet count less than 100000 suggests dengue. Packed cell volume rises above 40% and white cell count drops at the onset of the disease. If there is a drop in hemoglobin, blood pressure and packed cell volume simultaneously, overt bleeding should be suspected. Conjunctival, gastrointestinal and urinary bleeding may complicate dengue. During recovery, urine output normalizes, leaked fluid reenters the circulation, packed cell volume drops, white cell count and platelet count start to rise. Patients should be admitted to hospital for close observation. Blood pressure, pulse pressure, heart rate half hourly and urine output four hourly should be monitored during the critical phase. Total fluid quota is 2milliliters per kilogram per hour. For a 50 Kg man, it is 4800 milliliters. There are special dengue observation charts to predict and manage impending complications.
Antiviral drugs are not usually indicated; treatment for dengue is supportive.
Malaria is a parasitic fever. Malaria is caused by Plasmodium protozoa that has three types; P. falciparum, P. ovale and P. malariea. Plasmadium protozoa injected into the blood stream by female Anopheles mosquito multiples inside red blood cells. They reach maturity and exit the red cells destroying it. This cycle usually lasts three days. Therefore, malaria symptom is a three day fluctuating fever pattern. Due to the destruction of red blood cells, hemolytic anemia occurs. Investigation for malaria will show an aggregation of platelets in deep vessels of brain, liver, heart, spleen and muscles. This is called sequestration (usually occurs in falciparum infection). After the red cell phase, the protozoa enter the liver. They multiply in liver cells. This results in liver cell death and sometimes liver failure. There is a yellowish discoloration of mucus membranes. Blood smear examined under the microscope may show stages of malaria parasite life cycle in red blood cells. Quinolone, quinine, and chloroquine are some effective drugs for the treatment of malaria.
What is the difference between Dengue and Malaria?
• Dengue is a viral illness while malaria is parasitic.
• Fever patterns of the two diseases are different. Dengue fever starts about three days after infection and subsidies while malaria features a benign tertian fever.
• There is no fluid leakage in malaria.
• Dengue reduces platelet count while malaria does not.
• There may be an eosinophil leukocytosis in malaria while dengue causes a leukocytopenia.