Cholera is acute diarrheal infection caused by the bacterium Vibrio cholerae. His transmission case for oral contact, directly or indirectly with feces or contaminated food and in severe cases can lead to dangerous phenomena of dehydration. In the nineteenth century cholera spread repeatedly from its original area around the delta of the Ganges to the rest of the world, giving rise to six pandemics (for pandemic means a manifestation of a disease epidemic on a massive scale, even global) that have killed millions of people around the world.
The seventh pandemic is still in progress: started in 1961 in South Asia, reaching Africa in 1971 and America in 1991. Today the disease is considered endemic in many countries and the bacterium that causes it has not yet been eliminated from the environment.
The Vibrio cholerae serogroups that cause disease are two Vibrio cholerae 01 and Vibrio cholerae 0139. The most important reservoir of these pathogens are represented by man and water, especially those occurring in brackish estuaries, often rich in algae and plankton.
The 01 serogroup causes most epidemics, according to recent studies, climate change could encourage the formation of environments suitable for its spread. Serogroup 0139, however, was identified in 1992 in Bangladesh and, for now, its spread has been found only in Southeast Asia. The other groups of Vibrio cholerae can cause weak forms of diarrhea, but do not develop into genuine epidemics.
Cholera is a disease transmitted fecal-oral route: it can be contracted after the ingestion of food or water contaminated by fecal material of infected individuals (sick or healthy carriers or recovering). The foods most at risk for transmitting disease are uncooked or undercooked and, particularly seafood. Other foods may serve as a vehicle anyway.
The poor sanitary conditions in some countries and poor management of sewage and drinking water are the main causes of cholera epidemics. The bacteria can live in natural environments such as brackish rivers and coastal areas: why the risk of being infected by ingestion of shellfish is high.
Without contamination of food or water, direct infection from person to person is very rare in normal health conditions. The bacterial infection is necessary for transmission fact, more than one million: thus it is very difficult to infect others through simple contact.
Symptoms and Diagnosis
The incubation period of the disease usually varies between 24 and 72 hours (2-3 days), but in exceptional cases may vary between 2 hours and 5 days, depending on the number of bacteria ingested. In 75% of people infected show no symptoms. In contrast, among those who show only a small proportion develops a severe form of the disease.
When present, the main symptom is diarrhea, watery and brown the top clear liquid and then (this is the look for “rice water”). In some subjects the continued loss of fluid can lead to dehydration and shock, which in severe cases can be rapidly fatal. Fever is not a main symptom of the disease, can occur while vomiting and leg cramps.
The most important aspect in treatment of cholera is the reintegration of fluids and salts lost through diarrhea and vomiting. Oral rehydration is successful in 90% of cases may be via recruitment solutions rich in sugars, electrolytes and water, and must be taken immediately.
Severe cases require, instead, that a restoration of intravenous fluids, especially at first, requires large volumes of liquid, up to 4.6 liters. With adequate rehydration only 1% of patients die, and usually, after the restoration of fluid, the disease resolves itself.
Antibiotics, usually tetracycline or ciprofloxacin may shorten the course of the disease and reduce the intensity of symptoms and are used mainly for more severe forms or in patients at risk, such as the elderly.
The approach adopted to combat cholera is often multi-sectoral, involving water management, public health, fisheries, agriculture and health education. However, the most important interventions for the prevention of epidemics of cholera and water purification affect the functioning of the sewerage system.
Ensuring the safety of food and water and improve sanitation are, in fact, the basic conditions for preventing epidemics. Even education in respect of hygiene precautions during the preparation of food intake, such as washing hands with soap before you start cooking or eating, can help reduce the spread of epidemics. The cholera vibrios are in fact extremely sensitive to the action of common detergents and disinfectants.
Vaccines are also available: however, their effectiveness, along with that of vaccination campaigns, has yet to be assessed and investigated.