Means of transmission: One can get the cholera disease by drinking contaminated water or contaminated food by fecal contamination. Raw or undercooked shellfish can be naturally contaminated and if eaten spread the disease to humans. (2)
Usual reservoirs: Cholera can spread rapidly in areas where sewage treatments are not adequate. The contaminated food or water from the contaminated feces of an infected person with the cholera disease can spread in these areas. (4) In Texas, some shellfish from the Gulf of Mexico have been found to have the cholera disease. (4) Luckily, cholera does not spread from one human to another unless in contact with the contaminated feces. (4)
Etiologic agent: Vibrio cholerae serogroup 01 or 0139 that produces cholera toxin. (2)
General Characteristics: Cholera is a gram-negative bacillus. (1) It is a facultative anaerobe. (5) It has a short, curved, motile rod.
Key Tests: Direct rectal swabs or fresh stool is used for identification. (5) Darkfield microscopy of stools reveals large numbers of short, curved, rods with motility that looks like shooting stars. The rectal swabs that are used have to be sent on Cary-Blair medium. (6) Because cholera has the same symptoms as shigellosis, salmonellosis, campy lobacteriosis the lab tech needs to look for the lack of polymorphonuclear leukocytes because all these other diseases have them and cholera does not. (6)
Historical information: In the 1800ís cholera crossed Europe to North America by seafood contaminated ballast water. This water was taken abroad the ship in order to stabilize it. It was picked up in Asia and emptied into the harbors of Peru. From 1991-1994 an epidemic broke out in Latin America and resulted in one million cases of cholera and 9600 deaths. (7)
Signs and Symptoms: Many people who contact cholera are asymptomatic. These cases are obviously the mild cases. Others may have mild diarrhea, sudden onset of vomiting, watery diarrhea, body weight loss because of loss of fluids, and after water bowel stools, the stools begin to look like ìrice waterî. (6) There will be an electrolyte imbalance as the result of the diarrhea. (1) In sever cases, circulatory collapse and shock might occur. (2) Death can ever occur in patients with severe diarrhea because of fluid loss and salts. (2) Leg cramps is another symptom. (4) The incubation period is from day one to day three. Other effects of loss of fluid and electrolytes are thirst, oliguria, muscle cramps, weakness, loss of tissue turgor, sunken eyes, and wrinkling of skin on fingers. (5)
Virulence: Cholera can grow will in some foods such as rice but doesnít tolerate acidic foods, including carbonated beverages. It is killed by heat. The fact that it produces toxins, endotoxins, and enterotoxins make it more virulent. It also has good motility because of its flagella. (1)
Treatment: Rehydration is an important step in treating cholera infected patient. Patient can be rehydrated through oral rehydration or in severe cases through IV solutions if fluids cannot be kept down otherwise. Antibiotics are used, usually tetracycline or doxycycline. These will decrease the duration of the illness. (3) The amount of fluid replacement for continuing losses should be equal measured in stool volume. Hydration is confirmed through evaluation of pulse, skin turgor, strength, and urine output. Early treatment is the key. It can reduce stool volume by 50% and stop diarrhea within 48 hours. (5)
Control: Enteric precautions and careful hand washing. Bacterial solutions can provide decontamination of the disease. (6)
Prevention: the CDC investigates Cholera whenever it occurs. Lab techs are being trained to identify Vibrio cholerae. CDC is also providing diagnosis, treatment, and prevention; of cholera to the public health care officials so they are aware of it and educated. Educating the public also helps so they will be aware of the signs/symptoms and take the necessary precautions. (4)
Vaccine: Wyeth-Ayerst was a cholera vaccine sold in the United States but is discontinued now due to the fact that it has brief and incomplete immunity against cholera. There are no requirements to be vaccinated against cholera upon entering or exiting any country. There are two vaccines for cholera that are available in other countries. They are called Dukoral, Biotec AB and Mutacol, Berna. They provide better immunity than the first found and they have fewer side effects. These vaccines are not recommended for travelers and are not available in the U.S. (3)
Bibliography
1. MMID. "Vibrio cholerae." (March, 1999). Retrieved April 23, 2002, www. medinfo.ufl.edu/year2/mmid/bms5300/bugs/vibchole.html.
2. CDC. "Cholera'. (March, 2001). Retrieved April 22, 2002, www.cdc.gov/ncidod/dbmd/diseaseinfo/cholera_t.htm
3. CDC. "Cholera Information for Travelers". (October, 200) Retrieved April 22, 2002, www.cdc.gov/travel/cholera.htm
4. CDC. "Cholera". (June, 2001). Retrieved April 22, 2002, www.cdc.gov/ncidod/dbmd/diseaseinfo/cholera_g.htm
5. Merk Manual. "Cholera". (June, 2001). Retrieved April 29, 2002, www.merck.com/pubs/mmanual/section13/chapter157/157d.htm.
6. TDH. "Vibrio cholerae as a Bioterrorist Agent.î"(July, 2001). Retrieved April 29, 2002, www.tdh.state.tx.us/bioterrorism/facts/cholera.html.
7. Case, Funke, Tortora. (2001). Microbiology: An Introduction. Benjamin Cummings.