12-05-2008, 07:36 AM
As an outbreak spreads in Zimbabwe, what are the symptoms and how can it be tackled?
by Angela Balakrishnan
Where does cholera come from?
The disease was originally endemic to the Indian subcontinent, particularly around the Ganges river. Trade routes by land and sea helped spread it to Russia, then to western Europe, then America during the Irish immigration period. Cholera is no longer considered a pressing health threat in Europe and North America due to filtering and chlorination of water supplies, but still heavily affects developing countries.
How is it spread?
By bacteria in food or water. People who are infected suffer from acute liquid diarrhoea, which is full of the bacteria. If this gets into waterways, groundwater or drinking supplies, it can infect other people. Any foods washed in the water, as well as shellfish living in the affected waterway, can carry the bug. Cholera exists mainly as a seasonal disease, occurring mostly during rainy seasons. It is rarely spread directly from person to person.
When was it discovered to be waterborne?
The discovery of cholera as a waterborne disease came after a study by Dr John Snow, who analysed deaths during the London outbreak of 1854. Until then, people believed the disease was spread through bad air. Snow studied a water pump in Broad Street - now Broadwick Street - in Soho where, during the summer of the outbreak, people had been drinking cold water rather than boiling it.
The majority who died, Snow discovered, drank from the Broad Street pump, while inmates of a workhouse in nearby Poland Street who used another pump were unaffected. Snow got the authorities to remove the Broad Street pump handle. The number of infections and deaths fell rapidly. The John Snow pub on Broadwick Street was named to honour his work.
Who can be affected?
Recent research suggests an individual's susceptibility to cholera is affected by blood type. Those with type O blood are said to be the most susceptible, while those with type AB are the most resistant.
For cholera to affect a healthy adult, about 1m bacteria must be ingested. Those with a weak immune system or who are malnourished are more susceptible, which is why cholera outbreaks are still seen in developing countries.
What are the symptoms?
They include acute diarrhoea that can cause severe dehydration and fever, as well as nosebleeds, rapid pulse, dry skin, tiredness and vomiting. The symptoms develop so rapidly that a healthy person can be debilitated within an hour of the disease first starting to show. Infected patients may die within three hours if medical treatment is not provided.
How can cholera be treated?
Replacement of fluids lost through diarrhoea is essential. Medics recommend drinking fluids as a highly effective, safe, uncomplicated and inexpensive method. In severe cases, intravenous rehydration may be necessary. Speed usually determines the success of treatment: if cholera is treated quickly and properly, the mortality rate is less than 1%, but if it is left untreated the rate jumps to 50-60%.
How can it be prevented?
Advanced water purification and sewage systems mean the developed world no longer faces a major threat from cholera. The disposal and sterilisation of anything that may be infected is an important way of stopping its spread. Treatment of sewage before it enters water supplies is vital, and water that is used for drinking, washing or cooking should be sterilised by boiling or chlorination.
In developing countries, medical charities often offer public health education to help prevent and control transmission. In recent years substantial progress has been made developing new oral vaccines.
What is happening in Zimbabwe?
An outbreak of cholera first reported three weeks ago has developed into an epidemic that has forced the government to declare a state of emergency. A collapse in the healthcare system means that cases are rising by the thousands. So far, more than 550 people have died. No water at pumps and broken sewage pipes mean the disease is easily spread.
Apart from Zimbabwe, where else have there been epidemics?
The first big cholera outbreak was recorded around 1816, starting in Bengal and spreading through India as far as China and the Caspian Sea. The last serious spread in the west happened in Hamburg, Germany, in 1892, killing more than 8,000 people. There were a few reported incidents of cholera in the US in 2005 after hurricane Katrina struck New Orleans. The Democratic Republic of the Congo had a small spike in cases last month in the eastern district of Goma.
by Angela Balakrishnan
Where does cholera come from?
The disease was originally endemic to the Indian subcontinent, particularly around the Ganges river. Trade routes by land and sea helped spread it to Russia, then to western Europe, then America during the Irish immigration period. Cholera is no longer considered a pressing health threat in Europe and North America due to filtering and chlorination of water supplies, but still heavily affects developing countries.
How is it spread?
By bacteria in food or water. People who are infected suffer from acute liquid diarrhoea, which is full of the bacteria. If this gets into waterways, groundwater or drinking supplies, it can infect other people. Any foods washed in the water, as well as shellfish living in the affected waterway, can carry the bug. Cholera exists mainly as a seasonal disease, occurring mostly during rainy seasons. It is rarely spread directly from person to person.
When was it discovered to be waterborne?
The discovery of cholera as a waterborne disease came after a study by Dr John Snow, who analysed deaths during the London outbreak of 1854. Until then, people believed the disease was spread through bad air. Snow studied a water pump in Broad Street - now Broadwick Street - in Soho where, during the summer of the outbreak, people had been drinking cold water rather than boiling it.
The majority who died, Snow discovered, drank from the Broad Street pump, while inmates of a workhouse in nearby Poland Street who used another pump were unaffected. Snow got the authorities to remove the Broad Street pump handle. The number of infections and deaths fell rapidly. The John Snow pub on Broadwick Street was named to honour his work.
Who can be affected?
Recent research suggests an individual's susceptibility to cholera is affected by blood type. Those with type O blood are said to be the most susceptible, while those with type AB are the most resistant.
For cholera to affect a healthy adult, about 1m bacteria must be ingested. Those with a weak immune system or who are malnourished are more susceptible, which is why cholera outbreaks are still seen in developing countries.
What are the symptoms?
They include acute diarrhoea that can cause severe dehydration and fever, as well as nosebleeds, rapid pulse, dry skin, tiredness and vomiting. The symptoms develop so rapidly that a healthy person can be debilitated within an hour of the disease first starting to show. Infected patients may die within three hours if medical treatment is not provided.
How can cholera be treated?
Replacement of fluids lost through diarrhoea is essential. Medics recommend drinking fluids as a highly effective, safe, uncomplicated and inexpensive method. In severe cases, intravenous rehydration may be necessary. Speed usually determines the success of treatment: if cholera is treated quickly and properly, the mortality rate is less than 1%, but if it is left untreated the rate jumps to 50-60%.
How can it be prevented?
Advanced water purification and sewage systems mean the developed world no longer faces a major threat from cholera. The disposal and sterilisation of anything that may be infected is an important way of stopping its spread. Treatment of sewage before it enters water supplies is vital, and water that is used for drinking, washing or cooking should be sterilised by boiling or chlorination.
In developing countries, medical charities often offer public health education to help prevent and control transmission. In recent years substantial progress has been made developing new oral vaccines.
What is happening in Zimbabwe?
An outbreak of cholera first reported three weeks ago has developed into an epidemic that has forced the government to declare a state of emergency. A collapse in the healthcare system means that cases are rising by the thousands. So far, more than 550 people have died. No water at pumps and broken sewage pipes mean the disease is easily spread.
Apart from Zimbabwe, where else have there been epidemics?
The first big cholera outbreak was recorded around 1816, starting in Bengal and spreading through India as far as China and the Caspian Sea. The last serious spread in the west happened in Hamburg, Germany, in 1892, killing more than 8,000 people. There were a few reported incidents of cholera in the US in 2005 after hurricane Katrina struck New Orleans. The Democratic Republic of the Congo had a small spike in cases last month in the eastern district of Goma.