Rat-bite Fever
Rat-bite Fever
Disease History, Characteristics, and Transmission
Introduction
Rat-bite fever (RBF) is an acute infectious disease in humans caused by the scratch or bite of rodents, mostly rats, infected with one of two bacteria, Streptobacillus moniliformis or Spirillum minus. It is not transmitted from person to person. Scratches and bites are not necessarily the only way to contract the infection. Both bacteria are also able to be passed from rodents to humans through urine or mucous secretions from the eyes or nose of infected rats.
Rat-bite fever occurs most often among biomedical laboratory technicians, pet store employees who handle rodents, and people who have rodents as pets. It also occurs among people who live in rat-infested conditions. Children are more likely to be infected, both from their time spent inside and outdoors. Other animals that can carry the infectious bacteria are cats, dogs, gerbils, mice, squirrels, and weasels. The disease is also known as Haverhill fever and epidemic arthritic erythema (redness).
WORDS TO KNOW
ABSCESS: An abscess is a pus-filled sore, usually caused by a bacterial infection. It results from the body's defensive reaction to foreign material. Abscesses are often found in the soft tissue under the skin, such as the armpit or the groin. However, they may develop in any organ, and they are commonly found in the breast and gums. Abscesses are far more serious and call for more specific treatment if they are located in deep organs such as the lung, liver, or brain.
ERYTHEMA: Erythema is skin redness due to excess blood in capillaries (small blood vessels) in the skin.
SEPTIC: The term “septic” refers to the state of being infected with bacteria, particularly in the bloodstream
Disease History, Characteristics, and Transmission
Symptoms from the bacteria Streptobacillus moniliformis begin two to 22 days (usually within 10 days) after an initial bite or scratch. The infection can also be acquired by drinking contaminated milk or water (this form of the disease is sometimes referred to as Haverhill fever).
Symptoms are similar to severe influenza (flu), with a moderate fever (101–104°F [38.3–40.0°C]), chills, nausea, vomiting, headache, joint and back pain, gastrointestinal problems, and a reddish-pink rash (usually erupting about three days after initial contact with the bacteria) made of tiny bumps located generally on the palms of the hands and the soles of the feet.
Infections from the bacterium Spirillum minus are more common than infections with the other bacterium that causes rat-bite fever. With this bacterium, the infection is called spirillary rat-bite fever, or is sometimes known as sodoku. Symptoms do not begin until four to 28 days (usually less than 10 days) after exposure, and after the wound made by the bite or scratch has already healed. After the wound appears to initially heal, it suddenly becomes swollen and chronically inflamed.
Symptoms include fever, chills, and headache. The fever lasts longer than with Streptobacillus moniliformis, and may also reoccur over a period of months. Gastrointestinal symptoms are less severe than with the Haverhilltype fever. The rash is a light rosy color, causes itching, and covers most or all of the body. Joint and muscle pain does not usually occur or, if it does, it is much less severe than with the Haverhill-type fever.
Scope and Distribution
The infection caused by the bacterium Streptobacillus moniliformis has been found in the past to occur in the United States. With this bacterium, the infection is commonly called streptobacillary rat-bite fever. According to the Division of Bacterial and Mycotic Diseases, of the U.S. Centers for Disease Control and Prevention (CDC), it is rarely reported in the United States today and, consequently, accurate statistics on the incidence of the disease are not known.
The infection caused by the bacterium Spirillum minus is usually found in Asia and Africa, and its prevalence is much more common.
Treatment and Prevention
The bacterium Streptobacillus moniliformis is identified by a culture of blood or fluid that is taken from one of the affected joints of the infected human. The culture is then analyzed in a laboratory.
Antibiotics including procaine penicillin G or penicillin V by mouth (orally) are the most common treatments for streptobacillary rat-bite fever. If the patient is allergic to penicillin, erythromycin can be provided orally. Treatment is usually successful, although the infection can be sometimes eliminated by the human body itself, given sufficient time. However, if left untreated and when the body is unable to eliminate the disease, it can develop into serious complications such as septic (infectious) arthritis, abscesses (infections) to any tissue or organ of the body, endocarditis (inflammation of the heart's lining); meningitis (inflammation of the lining surrounding the brain and spine); and pneumonia (inflammation of the lungs). Without treatment, death can result from complications about 13% of the time.
The disease caused by the bacterium Spirillum minus is identified by examining blood or tissue removed from the wound of the infected human. Spirillary rat-bite fever is usually treated with procaine penicillin G or penicillin V by mouth. If the patient is allergic to penicillin, tetracycline can be given orally. If it is not treated, the fever usually subsides, but returns again in cycles of two to four days, which can continue for up for one year. In most circumstances, the illness, even without treatment, will resolve itself within four to eight weeks.
With both forms of rat-bite fever, the CDC Division of Bacterial and Mycotic Diseases recommends that humans avoid contact with animals capable of passing on the bacterial organisms. If contact cannot be avoided with rodents, recommendations include wearing gloves, regularly washing hands, and avoiding hand-to-mouth contact while handling rodents and cleaning their cages. With streptobacillary rat-bite fever, drinking only pasteurized milk and water from safe sources can help prevent the disease.
Impacts and Issues
Rat-bite fever and other types of rodent infestations contribute greatly to the decline of already poor communities. Rodents cause extensive losses of food and destruction of property when they are present in large numbers. They can cause damage and loss of revenue to grocery stores, warehouses, cargo carriers, and homes. Rodents can also cause loss of property due to fires from the gnawing of electrical wiring.
Sometimes rodents are controlled improperly with poisons, which exaggerates the problems already present. Health and safety problems can occur, especially among children, domesticated animals and pets, and the environment with improper poison use.
Along with rat-bite fever, large populations of rats within communities can increase the chance of contracting diseases such as hantavirus, leptospirosis (also called Weil's disease, canicola fever, and 7-day fever), plague, salmonella, and typhoid. These diseases can be potentially deadly, especially among the young and elderly.
See AlsoBacterial Disease; Vector-borne Disease; Zoonoses.
BIBLIOGRAPHY
Books
Committee on Infectious Diseases of Mice and Rats, Institute of Laboratory Animal Resources, Commission on Life Sciences, National Research Council. Infectious Diseases of Mice and Rats. Washington, DC: National Academy of Sciences, 1991.
Richardson, V.C.G. Diseases of Small Domestic Rodents. Oxford, UK, and Malden, MA: Blackwell Publishing, 2003.
Periodicals
Elliott, S.P. “Rat Bite Fever and Streptobacillus moniliformis.” Clinical Microbiology Reviews. January 1, 2007: 20 (1): 13–22.
Web Sites
Centers for Disease Control and Prevention. “Rat-bite Fever.” October 26, 2006 <http://www.cdc.gov/ncidod/dbmd/diseaseinfo/ratbitefever_g.htm#whatisrbf> (accessed March 18, 2007).
Rat-Bite Fever
Rat-Bite Fever
Definition
Rat-bite fever refers to an infection which develops after having been bitten or scratched by an infected animal.
Description
Rat-bite fever occurs most often among laboratory workers who handle lab rats in their jobs, and among people who live in poor conditions, with rodent infestation. Children are particularly likely to be bitten by rodents infesting their home, and are therefore most likely to contract rat-bite fever. Other animals that can carry the types of bacteria responsible for this illness include mice, squirrels, weasels, dogs, and cats. One of the causative bacteria can cause the same illness if it is ingested, for example in unpasteurized milk.
Causes and symptoms
There are two variations of rat-bite fever, caused by two different organisms. In the United States, the bacteria Streptobacillus moniliformis is the most common cause (causing streptobacillary rat-bite fever). In other countries, especially Africa, Spirillum minus causes a different form of the infection (called spirillary rat-bite fever).
Streptobacillary rat-bite fever occurs up to 22 days after the initial bite or scratch. The patient becomes ill with fever, chills, nausea and vomiting, headache, and pain in the back and joints. A rash made up of tiny pink bumps develops, covering the palms of the hands and the soles of the feet. Without treatment, the patient is at risk of developing serious infections of the lining of the heart (endocarditis ), the sac containing the heart (pericarditis ), the coverings of the brain and spinal cord (meningitis ), or lungs (pneumonia ). Any tissue or organ throughout the body may develop a pocket of infection and pus, called an abscess.
Spirillary rat-bite fever occurs some time after the initial injury has already healed, up to about 28 days after the bite or scratch. Although the wound had appeared completely healed, it suddenly grows red and swollen again. The patient develops a fever. Lymph nodes in the area become swollen and tender, and the patient suffers from fever, chills, and headache. The skin in the area of the original wound sloughs off. Although rash is less common than with streptobacillary rat-bite fever, there may be a lightly rosy, itchy rash all over the body. Joint and muscle pain rarely occur. If left untreated, the fever usually subsides, only to return again in repeated two-to four-day cycles. This can go on for up to a year, although, even without treatment, the illness usually resolves within four to eight weeks.
Diagnosis
In streptobacillary rat-bite fever, found in the United States, diagnosis can be made by taking a sample of blood or fluid from a painful joint. In a laboratory, the sample can be cultured, to allow the growth of organisms. Examination under a microscope will then allow identification of the bacteria Streptobacillus moniliformis.
In spirillary rat-bite fever, diagnosis can be made by examining blood or a sample of tissue from the wound for evidence of Spirillum minus.
Treatment
Shots of procaine penicillin G or penicillin V by mouth are effective against both streptobacillary and spirillary rat-bite fever. When a patient is allergic to the penicillins, erythromycin may be given by mouth for streptobacillary infection, or tetracycline by mouth for spirillary infection.
Prognosis
With treatment, prognosis is excellent for both types of rat-bite fever. Without treatment, the spirillary form usually resolves on its own, although it may take up to a year to do so.
The streptobacillary form, found in the United States, however, can progress to cause extremely serious, potentially fatal complications. In fact, before antibiotics were available to treat the infection, streptobacillary rat-bite fever frequently resulted in death.
Prevention
Prevention involves avoiding contact with those animals capable of passing on the causative organisms. This can be an unfortunately difficult task for people whose economic situations do not allow them to move out of rat-infested buildings. Because streptobacillary rat-bite fever can occur after drinking contaminated milk or water, only pasteurized milk, and water from safe sources, should be ingested.
KEY TERMS
Abscess— A pocket of infection; a collection of pus.
Endocarditis— An inflammation of the lining of the heart.
Meningitis— An inflammation of the tissues covering the brain and spinal cord.
Pasteurization— A process during which milk is heated up and maintained at a particular temperature long enough to kill bacteria.
Pericarditis— An inflammation of the sac containing the heart.
Resources
ORGANIZATIONS
Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. 〈http://www.cdc.gov〉.
Rat-Bite Fever
Rat-bite fever
Definition
Rat-bite fever refers to an infection which develops in a person after being bitten or scratched by an infected animal.
Description
Rat-bite fever occurs most often among laboratory workers who handle lab rats in their jobs, and among people who live in poor conditions, with rodent infestation. Children are particularly likely to be bitten by rodents infesting their home and are, therefore, most likely to contract rat-bite fever. Other animals that can carry the types of bacteria responsible for this illness are mice, squirrels, weasels, dogs, and cats. One kind of bacteria can cause the same illness if it is ingested in unpasteurized milk or in water that has been contaminated with rat waste.
Demographics
About half of all cases of rat-bite fever occur in children.
Causes and symptoms
There are two variations of rat-bite fever, caused by two different organisms. In the United States, the bacteria Streptobacillus moniliformis is the most common cause (causing streptobacillary rat-bite fever). In other countries, especially Africa, Spirillum minus causes a different form of the infection (called spirillary rat-bite fever).
Streptobacillary rat-bite fever occurs up to 22 days after the initial bite or scratch. The patient becomes ill with fever, chills, nausea and vomiting , headache , and pain in the back and joints. A rash made up of tiny pink bumps develops, covering the palms of the hands and the soles of the feet. Without treatment, the patient is at risk of developing serious infections of the lining of the heart (endocarditis), the sac containing the heart (pericarditis), the coverings of the brain and spinal cord (meningitis ), or lungs (pneumonia ). Any tissue or organ throughout the body may develop a pocket of infection and pus, called an abscess.
Spirillary rat-bite fever occurs some time after the initial injury has already healed, up to about 28 days after the bite or scratch. Although the wound had appeared completely healed, it suddenly grows red and swollen again. Lymph nodes in the area become swollen and tender, and the patient develops fever, chills, and headache. The skin in the area of the original wound sloughs off. Although rash is less common than with streptobacillary rat-bite fever, there may be a lightly rosy, itchy rash all over the body. Joint and muscle pain rarely occur. If left untreated, the fever usually subsides, only to return again in repeated two- to four-day cycles. Though these cycles can last for a year, the illness usually resolves without treatment in four to eight weeks. This can go on for up to a year although, even without treatment, the illness usually resolves within four to eight weeks.
Diagnosis
In streptobacillary rat-bite fever diagnosis can be made by taking a sample of blood or fluid from a painful joint, which can be cultured to allow the growth of organisms. Examination under a microscope will then allow identification of the bacteria Streptobacillus moniliformis.
In spirillary rat-bite fever, diagnosis can be made by examining blood or a sample of tissue from the wound for evidence of Spirillum minus.
Treatment
Either injections of procaine penicillin G or penicillin V by mouth are effective against both streptobacillary and spirillary rat-bite fever. When a patient is allergic to the penicillins , either erythromycin may be given by mouth for streptobacillary infection or tetracycline by mouth for spirillary infection.
Prognosis
With treatment, prognosis is excellent for both types of rat-bite fever. Without treatment, the spirillary form usually resolves on its own, although it may take up to a year to do so.
The streptobacillary form, found in the United States, however, can progress to cause extremely serious, potentially fatal complications. In fact, before antibiotics were available to treat the infection, streptobacillary rat-bite fever frequently resulted in death.
Prevention
Prevention involves avoiding contact with those animals capable of passing on the causative organisms. This can be a difficult task for people whose economic situations do not allow them to move out of rat-infested buildings. Because streptobacillary rat-bite fever can occur after drinking contaminated milk or water, only pasteurized milk, and water from safe sources, should be ingested.
Parental concerns
The parents of children living in rodent-infested conditions, or who have pet rodents (mice, rats, gerbils) should be vigilant to illness in their children.
KEY TERMS
Abscess —A localized collection of pus in the skin or other body tissue caused by infection.
Endocarditis —Inflammation of the inner membrane lining heart and/or of the heart valves caused by infection.
Meningitis —An infection or inflammation of the membranes that cover the brain and spinal cord. It is usually caused by bacteria or a virus.
Pasteurization —A process during which milk is heated and maintained at a particular temperature for the purpose of killing, or retarding the development of, pathogenic bacteria.
Pericarditis —Inflammation of the pericardium, the sac that surrounds the heart and the roots of the great blood vessels.
Resources
BOOKS
Barnett, S. Anthony. The Story of Rats: Their Impact on Us and Our Impact on Them. Crows Nest, New South Wales, Australia: Allen & Unwin, Pty., Limited, 2002.
Conniff, Richard. Rats: The Good, the Bad, and the Ugly. New York: Random House Children's Books, 2002.
Sullivan, Robert. Rats: Observation on the History and Habitat of the City's Most Unwanted Inhabitant. London: Bloomsbury Publishing, 2005.
ORGANIZATIONS
Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. Web site: <www.cdc.gov>.
WEB SITES
"Rat-bite fever." MedlinePlus. Available online at <www.nlm.nih.gov/medlineplus/ency/article/001348.htm> (accessed December 29, 2004).
Rosalyn Carson-DeWitt, MD