Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Three main factors determine treatments: the infecting species of Plasmodium parasite, the clinical situation of the patient (for
example, adult, child, or pregnant female with either mild or severe malaria), and the drug susceptibility of the infecting parasites. Drug susceptibility is determined by the geographic area where the infection was acquired. Different areas of the world have malaria types that are resistant to certain medications. The correct drugs for each type of malaria must be prescribed by a doctor who is familiar with malaria treatment protocols. Since people infected with
P. falciparum malaria can die (often because of delayed treatment), immediate treatment for
P. falciparum malaria is necessary.
Malaria is an infectious disease caused by a parasite, Plasmodium, which infects red blood cells. Malaria is characterized by cycles of chills, fever, pain, and sweating. Historical records suggest
malaria has infected humans since the beginning of mankind. The name "mal aria" (meaning "bad air" in Italian) was first used in English in 1740 by H. Walpole when describing the disease. The term was shortened to "malaria" in the 20th century. C. Laveran in 1880 was the first to identify the parasites in human blood. In 1889, R. Ross discovered that mosquitoes transmitted malaria. Of the four common species that cause malaria, the most serious type is
Plasmodium falciparum malaria. It can be life-threatening. However, another relatively new species,
Plasmodium knowlesi, is also a dangerous species that is typically found only in long-tailed and pigtail macaque monkeys. Like
P. falciparum, P. knowlesi may be deadly to anyone infected. The other three common species of malaria (P. vivax, P. malariae, and
P. ovale) are generally less serious and are usually not life-threatening. It is possible to be infected with more than one species of
Plasmodium at the same time.
Currently, about 2 million deaths per year worldwide are due to Plasmodium infections. The majority occur in children under 5 years of
age in sub-Saharan African countries. There are about 400 million new cases per year worldwide. Most people diagnosed in the U.S. obtained their infection outside of the country, usually while living or traveling through an area where malaria is endemic.
What are malaria symptoms and signs?
The symptoms characteristic of malaria include flulike illness with fever, chills, muscle aches, and headache. Some patients develop nausea, vomiting, cough, and diarrhea. Cycles of chills, fever, and sweating that repeat every
one, two, or three days are typical. There can sometimes be vomiting, diarrhea, coughing, and yellowing (jaundice) of the skin and whites of the eyes due to destruction of red blood cells and liver cells.
People with severe P. falciparum malaria can develop bleeding problems, shock, liver or kidney failure, central nervous system problems, coma, and can die from the infection or its complications. Cerebral malaria (coma, or altered mental status or seizures) can occur with severe
P. falciparum infection. It is lethal if not treated quickly; even with treatment, about 15%-20% die.
How is malaria transmitted?
The life cycle of the malaria parasite (Plasmodium) is complicated and involves two hosts, humans and
Anopheles mosquitoes. The disease is transmitted to humans when an infected
Anopheles mosquito bites a person and injects the malaria parasites (sporozoites) into the blood. This is shown in Figure 1, where the illustration shows a mosquito taking a blood meal (circle label 1 in Figure 1).
Figure 1: CDC illustration of the life cycles of malaria parasites, Plasmodium spp. SOURCE: CDC
Sporozoites travel through the bloodstream to the liver, mature, and
eventually infect the human red blood cells. While in red blood cells, the
parasites again develop until a mosquito takes a blood meal from an infected
human and ingests human red blood cells containing the parasites. Then the
parasites reach the Anopheles mosquito's stomach and eventually invade
the mosquito salivary glands. When an Anopheles mosquito bites a human,
these sporozoites complete and repeat the complex Plasmodium life cycle. P. ovale
and P. vivax can further complicate the cycle by producing dormant stages
(hypnozoites) that may not develop for weeks to years.
Kidney failure can occur from an acute event or a chronic condition or disease. Prerenal kidney failure is caused by blood loss, dehydration, medication. Some of the renal causes of kidney failure are from sepsis, medications, rhabdomyolysis, multiple myeloma, and acute glomerulonephritis. Post renal causes of kidney failure include bladder obstruction, prostate problems, tumors, or kidney stones. Treatment options included diet, medications, or dialysis.
Diarrhea is a change is the frequency and looseness of bowel movements. Cramping, abdominal pain, and the sensation of rectal urgency are all symptoms of diarrhea. Absorbents and anti-motility medications are used to treat diarrhea.
Headaches can be divided into two categories: primary headaches and secondary headaches. Migraine headaches, tension headaches, and cluster headaches are considered primary headaches. Secondary headaches are caused by disease. Headache symptoms vary with the headache type. Over-the-counter pain relievers provide short-term relief for most headaches.
Jaundice is a yellowish staining of the skin and whites of the eyes (sclerae) with bilirubin, the pigment found in bile. Jaundice can be an indicator of liver or gallbladder disease, or it may result from the rupture of red blood cells (hemolysis).
Chronic cough is a cough that does not go away and is generally a symptom of another disorder such as asthma, allergic rhinitis, sinus infection, cigarette smoking, GERD, postnasal drip, bronchitis, pneumonia, medications, and less frequently tumors or other lung disease. Treatment of chronic cough is dependant upon the cause.
Nausea is an uneasiness of the stomach that often precedes vomiting. Nausea and vomiting are not diseases, but they are symptoms of many conditions. The causes of vomiting differ according to age, and treatment depends upon the cause of nausea and vomiting.
Although a fever technically is any body temperature above the normal of 98.6 degrees F. (37 degrees C.), in practice a person is usually not considered to have a significant fever until the temperature is above 100.4 degrees F (38 degrees C.). Fever is part of the body's own disease-fighting arsenal: rising body temperatures apparently are capable of killing off many disease- producing organisms.
The spleen enlarges if it is asked to do excessive work in filtering or manufacturing blood cells, if there is abnormal blood flow to it, or if it is invaded with abnormal cells or deposits. Symptoms of an enlarged spleen may include weakness and fatigue, easy bleeding, and poor white blood cell function. Treatment of an enlarged spleen is focused toward the cause of the splenomegaly. Surgery may be required to remove the spleen.
Neutropenia is a marked decrease in the number of neutrophils, neutrophils being a type of white blood cell (specifically a form of granulocyte) filled with neutrally-staning granules, tiny sacs of enzymes that help the cell to kill and digest microorganisms it has engulfed by phagocytosis.
Epilepsy is a brain disorder in which the person has seizures. There are two kinds of seizures, focal and generalized. There are many causes of epilepsy. Treatment of epilepsy (seizures) depends upon the cause and type of seizures experienced.
Influenza (flu) is a respiratory illness caused by a virus. Flu symptoms include fever, cough, sore throat, runny nose, headache, fatigue, and muscle aches. The flu may be prevented with an annual influenza vaccination.
Coma is the inability to waken or react to the surrounding environment. The Glasgow Coma Scale is frequently used to measure the depth of coma. Causes of coma include trauma, bleeding, edema, lack of oxygen, poisoning, or hypoglycemia. Prognosis for a patient in a coma depends on the cause of the coma.
G6PD deficiency (Glucose 6-phosphate dehydrogenase) leads to a condition called hemolytic anemia. Causes of G6PD deficiency is an abnormal gene located in the X-chromosome, therefore, it is more common in males. Hemolytic anemia caused by G6PD deficiency generally occurs after exposure to malaria medications, antiitching drugs, and fava beans. Pneumonia and other infections can also precipitate hemolytic anemia in individuals with G6PD deficiency. Treatment is generally discontinuing the drug or compound treating infection. Blood transfusions are necessary in some individuals.
Fatigue can be described in various ways. Sometimes fatigue is described as feeling a lack of energy and motivation (both mental and physical). The causes of fatigue are generally related to a variety of conditions or diseases for example, anemia, mono, medications, sleep problems, cancer, anxiety, heart disease, drug abuse, and more. Treatment of fatigue is generally directed toward the condition or disease that is causing the fatigue.
Medical shock is a life-threatening medical condition. There are several types of medical shock, septic shock, anaphylactic shock, cardiogenic shock, hypovolemic shock, and neurogenic shock. Causes of shock include heart attack, heart failure, heavy bleeding (internal and external), infection, anaphylaxis, spinal cord injury, severe burns, chronic vomiting or diarrhea. Low blood pressure is the key sign of sock. Treatment is dependant upon the type of shock.
Alpha thalassemia is a disorder in which the alpha globin protein is underproduced. There are two pairs of genes that carry the code for the alpha chains of hemoglobin. When one gene is impaired, that person is in a carrier state and suffers no medical problems. When four genes are impaired, the production of fetal and adult hemoglobin is prevented, resulting in hydrops fetalis and leading to death before birth.
Seizures are divided into two categories: generalized and partial. Generalized seizures are produced by electrical impulses from throughout the brain, while partial seizures are produced by electrical impulses in a small part of the brain. Seizure symptoms include unconsciousness, convulsions, and muscle rigidity.
Drug resistance (antimicrobial resistance) is the ability of bacteria, fungi, parasites, and viruses to grow, even in the presence of a drug that would normally kill it (or limit it's growth). Drug resistance is a growing problem, particularly for infections such as MRSA, VRE (vancomycin-resistant enterococci), tuberculosis, HIV, STDs, gonorrhea, flu, pneumonia, malaria, E. coli, salmonella, Campylobacter, which causes diarrhea and gastroenteritis. Learn how to protect yourself from resistance to drugs.
Travelers should prepare for their trip by visiting their physician to get the proper vaccinations and obtain the necessary medication if they have a medical condition or chronic disease. Diseases that travelers may pick up from contaminated water or food, insect or animal bites, or from other people include malaria, meningococcal meningitis, yellow fever, hepatitis A, typhoid fever, polio, and cholera.
Children's health is focused on the well-being of children from conception through adolescence. There are many aspects of children's health, including growth and development, illnesses, injuries, behavior, mental illness, family health and community health.
Influenza, commonly called "the flu," is an illness caused by RNA viruses that infect the respiratory tract of many animals, birds, and humans. In most people, the infection results in the person getting fever, cough, headache, and malaise (tired, no energy); some people also may develop a sore throat, nausea, vomiting, and diarrhea. The majority of individuals has symptoms for about one to two weeks and then recovers with no problems. However, compared with most other viral respiratory infections, such as the common cold, influenza (flu) infection can cause a more severe illness with a mortality rate (death rate) of about 0.1% of people who are infected with the virus.
The above is the usual situation for the yearly occurring "conventional" or "seasonal" flu strains. However, there are situations in which some flu outbreaks are severe. These severe outbreaks occur when the human population is exposed to a flu strain against which the populati...