Scarlet Fever
Scarlet Fever
Disease History, Characteristics, and Transmission
Introduction
In the nineteenth century, scarlet fever was one of the most feared of all childhood diseases, with a mortality of up to 35%. The causative agent is the bacterium Streptococcus pyogenes. Today scarlet fever still exists, but tends to be a very mild disease in developed countries, although serious complications are still common in developing nations.
The modern, milder, form of scarlet fever is sometimes called pharyngitis (throat infection) with rash, or scarlatina. It is not clear why this disease has lost its virulence. Unlike other childhood diseases, vaccination has not played a role in reducing its toll. The microbe itself may have mutated into a milder pathogen, or improvements in hygiene may have contributed. The advent of antibiotics and drugs to treat seizures and fever has certainly helped deal with the cause and symptoms of scarlet fever.
Disease History, Characteristics, and Transmission
The S. pyogenes bacteria causing scarlet fever is known as Group A streptoccoccus (GAS); the “A” refers to a characteristic antigen protein that exists on the surface of the microbe. GAS also causes strep throat (sometimes called bacterial sore throat) and impetigo. It is also responsible for necrotizing fasciitis, which involves the soft tissue under the skin, and toxic shock syndrome, both of which are potentially fatal. Around 40% of the population are asymptomatic carriers of GAS and the bacterium does not have an animal reservoir (an organism that maintains the infective agent). The main symptoms of scarlet fever are a very sore, red throat, possibly with visible white or yellow patches, and the bright red rash that gives the disease its name.
The rash is caused by production of a toxin by the bacteria that spreads into the bloodstream via infected tissue in the throat. It begins as small spots on the neck and upper chest, it then spreads to the rest of the body. When the skin is pressed, it goes pale and the rash feels like sandpaper. The cheeks are flushed while the mouth remains pale, as if the patient had a white moustache. The tongue is often coated with a white fur, with tiny projections called papillae poking through. Doctors sometimes call this a “strawberry” tongue, from its appearance. After a few days, it turns into a “raspberry” tongue, becoming red with prominent papillae.
Other symptoms of scarlet fever include headache, vomiting, swollen glands, and poor appetite. As the rash fades, within three to four days of onset, the skin of the face, palms, and tips of the fingers and toes may begin to peel. More serious cases of scarlet fever—rare in the West, more common in the developing world—are divided into two types, known as toxic and septic. In the toxic form, fever can be extreme, accompanied by delirium, convulsions, and rapid pulse, leading to death within 24 hours. In the septic form, the course of the disease is more prolonged, causing death in two to three weeks.
The complications of scarlet fever include upper airway obstruction, meningitis, pneumonia, mastoiditis, and otitis media (a severe ear infection). Later complications, such as kidney disease and rheumatic fever—which weakens the heart in the long term—may also occur.
Scarlet fever is transmitted by coughs and sneezes, as the saliva and nasal fluids are infectious. Coming into contact with items contaminated with these fluids therefore carries a risk of infection. Sharing cups and utensils can transmit infection.
Scope and Distribution
Scarlet fever used to cause pandemics with high mortality in the nineteenth century in the United States, Western Europe, and in Scandinavia. Often, because of a lack of understanding of how the disease was transmitted, all the patient's belongings would be burned for fear of contamination. Long periods of convalescence were common, perhaps because of complications due to rheumatic fever.
Because scarlet fever is now a mild disease in the West, it is no longer notifiable (tracked through mandaory reporting) in many countries. The United Kingdom (UK), however, still collects data on scarlet fever cases and noted 2,200 cases occurring in England and Wales in 2004. Ten years previously, the number of cases was around 6,000, which suggests the disease is on the decline.
Ninety percent of cases of scarlet fever occur among children between the ages of two years and eight years. In temperate regions, the number of cases peaks in the winter months. Complications, such as rheumatic fever, ear infections, and pneumonia, are relatively common in developing countries.
Treatment and Prevention
Scarlet fever is treated with antibiotics, with penicillin being the most common drug used. For those allergic to penicillin, erthryomycin or clindamycin are often prescribed instead. Completing the course of treatment is essential to prevent the onset of rheumatic fever or other complications. The majority of patients make an uneventful recovery after treatment.
WORDS TO KNOW
GROUP A STREPTOCOCCUS (GAS): A type (specifically a serotype) of the streptococcus bacteria, based on the antigen contained in the cell wall.
NOTIFIABLE DISEASE: A disease that the law requires must be reported to health officials when diagnosed; also called a reportable disease.
RASH: A rash is a change in appearance or texture of the skin. A rash is the popular term for a group of spots or red, inflamed skin that is usually a symptom of an underlying condition or disorder. Often temporary, a rash is only rarely a sign of a serious problem.
RESERVOIR: The animal or organism in which the virus or parasite normally resides.
TOXIN: A poison that is produced by a living organism.
Paracetamol or ibuprofen are useful for treating the symptoms of scarlet fever. Cold liquids, like milkshakes and popsicles, and warm soup are useful for soothing throat pain, while a humidifier placed in the room will help ease dryness of the throat. In general, the patient should be kept very well hydrated, and get plenty of rest.
Good hygiene, including thorough handwashing, is very important in preventing the transmission of scarlet fever. Therefore, children with the illness, even if the case is mild, should be kept away from school or child care centers. Utensils belonging to a child who is sick at home should always be kept separate from those used by the rest of the family.
Impacts and Issues
When an infectious disease is notifiable, it allows public health authorities to mount an investigation and stop an outbreak from spreading. In 2006, the UK Health Protection Agency dealt with an outbreak of scarlet fever in the southern county of Wiltshire, where 50 cases were reported during January and February.
There were clusters of cases in two child care centers—16 in one, four in the other. Six of the 50 cases were in adults aged 18 years or more, while the rest occurred in children aged between eight months and ten years. Eleven cases had been reported during the same period of 2004 and only four in the same period of 2005. Therefore, this outbreak was unusual. In the first center, all children with symptoms received penicillin and were excluded for five days after beginning their treatment. The center closed down for several days. The second outbreak was reported on January 26, but no new cases were reported after January 31 in this child care center.
The local health protection team sent letters to all doctors in the area, informing them of the outbreaks. All suspected cases were to have throat swabs taken to test for the presence of GAS. This resulted in reports of 30 other cases of scarlet fever. The team also sent letters to the parents of all the children at the center to ask them to be on the alert for symptoms. However, they decided not to screen the children for GAS unless more serious scarlet fever cases were reported. Although they wanted to break the chain of transmission through asymptomatic carriers, they did not want to expose young children to antibiotics unnecessarily.
Samples from the throat swabs that had been taken were sent to the Health Protection Agency Centre for Infections for detailed analysis. These actions were taken because previous experience showed that outbreaks of scarlet fever can have serious consequences for the young patients if the infection is not treated promptly and adequately.
See AlsoImpetigo; Necrotizing Fasciitis; Strep Throat; Toxic Shock.
BIBLIOGRAPHY
Books
Wilson, Walter R., and Merle A. Sande. Current Diagnosis & Treatment in Infectious Diseases. New York: McGraw Hill, 2001.
Periodicals
Health Protection Agency. “Scarlet Fever Outbreak in Two Nurseries in South West England.” CDR Weekly 16 (March 2, 2006): 1–2.
Marshall, S. “Scarlet Fever: the Disease in the UK.” The Pharmaceutical Journal 277 (July 22, 2006): 115–116.
Web Sites
Centers for Disease Control and Prevention. “Scarlet Fever.” October 13, 2005. <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/scarletfever_g.htm> (accessed April 28, 2007).