http://new.paho.org/disasters/index.php?option=com_content&task=view&id=543&Itemid=904
Cholera in Disaster Situations

Cholera is an intestinal infection caused by toxigenic 
Vibrio cholerae,  group O-1 or O-139. Natural and man-made disasters which produce  overcrowding, a scarcity of safe drinking water, improper elimination of  human waste, and the contamination of food during or after its  preparation are risk factors for the spread of the disease.
Description
In areas where cholera has not been confirmed, a suspected case is  defined as severe dehydration or death from acute watery diarrhea in a  patient over 5 years of age.
In areas where an epidemic is under way, a suspected case of cholera  is defined as acute watery diarrhea, with or without vomiting, in a  patient over 5 years of age.
A confirmed case of cholera is defined as the laboratory-confirmed  presence of V. cholerae 01 in any patient with diarrhea. Once the  presence of the disease has been confirmed, it is unnecessary to examine  specimens from all cases or contacts. Monitoring should include ongoing  laboratory confirmation of a small proportion of cases.
It is important to adopt this definition. However, for clinical  management of cases of acute watery diarrhea in an area in which an  epidemic is under way, cholera should be suspected in all cases in  patients aged 2 or older. It should be noted that in Central America,  cholera primarily strikes adults, with 80% of the recorded cases  representing individuals 5 years of age or older, while 80% of diarrheal  diseases from other causes occur in children under 5.
There are more than 60 serogroups of Vibrio cholerae, but only the O1  serogroup causes cholera. V. cholerae occurs as two biotypes: classical  and El Tor. Each biotype has two serotypes: Ogawa and Inaba. The El Tor  biotype (first isolated in Egypt in 1905) is responsible for almost all  the recent outbreaks of the disease, producing a greater proportion of  asymptomatic infections than the classical biotype and surviving longer  in the environment. This biotype can live in association with certain  aquatic plants and animals, which makes water an important reservoir of  the infection.
History of Cholera in the Region
The second cholera pandemic spanned the period 1826 to 1837. This was  the first pandemic that ravaged England and Western Europe, causing  thousands of deaths in early 1830. The epidemic spread to Canada, the  United States, and Mexico in continental North America, to Guyana in  South America, and to Cuba.
In January 1991 Vibrio cholerae 01 reached a town on the coast of  Peru, trumpeting the arrival of the seventh cholera pandemic in Latin  America. By the year 2000 the epidemic had spread to 21 of the 35  countries of the Region of the Americas, with Canada, Uruguay, and the  Caribbean remaining free of the disease.
Moreover, in 1999 Argentina,  Bolivia, Chile, Costa Rica, French Guiana, Guyana, Paraguay, Panama, and  Suriname did not report cases of the disease.
In the 19th and early 20th century cholera was a predominantly urban  phenomenon with high case-fatality rates (30-50%). In contrast, the  Latin American epidemic of the 1990s was rural, with lower case-fatality  rates (around 2%). The disease is also becoming endemic, and an  incipient seasonal epidemiological model can be observed.
Risks for the Traveler
People who follow the usual tourist itineraries and observe food  safety recommendations face practically no risk when visiting countries  that have reported cases of cholera.
The 10 Most Frequently Asked Questions
Q. When we speak of cholera we often refer to it as a pandemic. What is a "pandemic"?
A pandemic is a disease that strikes the majority of the population  in a large region, emerges simultaneously in different parts of the  world, and is a long-term phenomenon.
Q. Is cholera as widespread and serious now as it used to be?
No. In the 19th century cholera was found in major cities, causing  high case-fatality rates (30%-50%), while today the infection is often  mild, self-limiting, or subclinical and is found in rural areas, with  relatively low case-fatality rates (2%).
Q. What led to the changes in the model of the disease?
The following factors can be mentioned: (a) El Tor, a biotype of V.  cholerae in circulation, which produces a greater proportion of  asymptomatic cases than the classical biotype; (b) greater access to  safe drinking water; (c) better excreta disposal systems; (d) health  education, and (e) primary health care.
Q. Is it possible to contract V. cholerae through person-to-person contact?
It is possible, but this type of transmission is very rare.
Q. What are the main steps in managing a suspected case of cholera?
The main steps are: assess for dehydration, rehydrate with a solution  of oral rehydration salts, observe the patient, replace missing fluids,  administer oral antibiotics only to patients with serious dehydration,  and feed the patient.
Q. Do we need a health system with a high level of complexity to treat cholera?
Fluids and simple electrolyte replacement therapy produce excellent  results in the majority of cases. Serious cases may require antibiotics  (doxycycline or tetracycline for adults; trimethoprim sulfamethoxazole  for children). These interventions can be carried out at the primary  level.
Q. Are travel and trade restrictions recommended in outbreaks of cholera?
No. Travel and trade restrictions between countries or between  different areas of a country do not prevent the spread of cholera. Not  only are they ineffective, they lead to the suppression of information  on outbreaks of the disease. WHO modified its International Health  Regulations in 1973 so that travelers would no longer be required to  show a certificate of vaccination against cholera.
Q. Are vaccinations recommended for cholera control?
No. The traditional vaccine against cholera (based on whole, killed  cells) is characterized by low levels of efficacy and high  reactogenicity. Therefore, it is not recommended for the control of  epidemics. The new vaccines might be considered, but with these, there  is a rapid loss of protection, giving people a false sense of security.  Resources should be channeled to the most useful control methods.
Q. How do we protect young children against cholera?
In infants under 6 months, breast-feeding protects against the  disease. Careful preparation of formula and food with safe drinking  water should protect infants who are not breast-fed.
Q. Is it mandatory to report cholera outbreaks?
Yes. The diseases listed as reportable by the International Health  Regulations are cholera, yellow fever, and the plague. WHO publishes the  data on cholera outbreaks in the Weekly Epidemiological Record; the CDC  publishes its semiweekly "Health Information for International Travel"  to inform the public about where cholera and yellow fever have been  reported.
What to Do at the Institutional and Community Level
- Adopt long-term policies to ensure that all populations have access  to adequate systems for excreta disposal and the provision of safe  drinking water; 
 
- Offer basic health services through primary health care systems. The  majority of cholera cases respond well to simple therapies; Prescribe  antibiotics only for cholera cases showing signs of severe dehydration; 
 
- Monitor the susceptibility of V. cholerae to antibiotics;  
 
- Maintain specificity in reports, employing the case definitions developed by PAHO/WHO;  
 
- Update the epidemiological profile of areas with cholera or considered at risk for the disease;  
 
- Offer periodic training to physicians and paramedical personnel for the clinical management of patients with acute diarrhea;  
 
- Maintain a stock of essential emergency supplies, especially oral  rehydration salts (ORS) and solution and appropriate antibiotics.  
 
- Maintain a buffer stock of drugs at appropriate points in the drug administration system;  
 
- Emphasize safe disposal of human excreta through health education;  
 
- Construct sanitary systems for human waste disposal, suited to the local conditions.  
 
- Promote community production of chlorine so that it can supply itself.
 
What to Do at the Personal Level
- Drink only safe water (tap water, boiled for a minute or more, or  water that has been disinfected with chlorine or iodine tablets); 
 
- Avoid raw food (except fruits or vegetables that can be peeled);  
 
- Cook food until hot both inside and out and eat while still hot;  
 
- Carefully wash and dry kitchen or serving utensils;  
 
- Wash hands carefully with soap after using the toilet and before preparing or eating food or feeding children;  
 
- In emergencies, while a better latrine is being constructed, a  simple pit (0.3m x 0.3 m x 0.5 m) can be dug at least 30 meters from the  well or other source of drinking water. Latrines should be located  below the level of the water source. Avoid swampy ground.
 
What Not to Do
- Do not eat mollusks, shellfish, or other fish or seafood from polluted waters, unless they are cooked thoroughly; 
 
- Do not eat raw vegetables;  
 
- Do not wash kitchen utensils or eat with water known to be contaminated;  
 
- Do not bathe in water known to be contaminated;  
 
- Do not mix raw food with cooked food;  
 
- Do not drink milk that has not been pasteurized, unless it has been boiled adequately;  
 
- Do not eat ice cream or use ice, unless it is from a safe source;  
 
- Do not take antibiotics, unless prescribed by a health worker;  
 
- Do not issue a quarantine in an effort to control the spread of cholera.
 
Suggested Readings
- "WHO Guidelines for cholera control", Revised 1992 WHO/CDD/SER.80.4  REV 4 (1992) Orig. English. Spanish version: "Lineamientos para el  control del cólera". 
 
- WHO "Guidance on formulation of national policy on the control of  cholera" WHO/CDD/SER/92.16 REV.1 Original Spanish-English version:  "Lineamientos de la OPS para formular una polÃtica nacional de control  del cólera". 
 
- WHO "Diarrhea management training course: guidelines for conducting  clinical training courses at health centers and small hospitals" Geneva,  WHO, 1990 WHO/CDD/SER/90.2 (English only) 
 
- WHO "Guide to simple sanitary measures for the control of enteric diseases". Geneva, WHO, 1974 (English only) 
 
- Manual for laboratory investigations of acute enteric infections. WHO/CDD/83.3 Geneva, WHO, 1987 
 
- The treatment and prevention of acute diarrhea: practical  guidelines. 2 ed. WHO, 1989 (Available in English, French, Portuguese,  and Spanish) 
 
- Manejo de los pacientes con cólera. WHO/CDD/SER/91.15 Rev. 1 (1992) Geneva, WHO, 1992 
 
- CDC -Centers for Disease Control and Prevention "Health Information for International Travel" 1999-2000 DHHS, Atlanta, GA. On-line version. 
 
- "Textbook of International Health" by Paul F. Basch (Chapter 1 -  Historical Background) Department of Health Research and Policy,  Stanford University School of Medicine. Oxford University Press (1990) 
 
- La Investigación de las Dolencias Infecciosas en la Historia (Las  seis primeras pandemias - pp 274-284) Arturo Romero B, MD Academia  Colombiana de Ciencias Exactas, FÃsicas y Naturales. Colección Enrique  Pérez Arbeláez, No. 12 Santafé de Bogotá, DC Colombia, 1997 
 
Contact
Dr. Marlo Libel
Phone: (202) 974-3129 
Email:   
libelmar@paho.org