Waterborne diseases | Science| In-depth reporting on science and technology | DW | 24.07.2015
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Science

Waterborne diseases

Certain diseases are transmitted by contaminated water. But which are the most dangerous ones and how can you protect yourself?

Cholera

Cholera is an infectious disease of the small intestine. It is caused by "Vibrio cholerae" bacteria. People get infected because of contaminated drinking water or infected food. They suffer from extreme diarrhea and vomiting. The body rapidly loses liquid - and dries out. Electrolytes, such as sodium, potassium, calcium and magnesium disappear - but these substances are extremely important for the function of the cells.

In order to treat the disease, liquid, sugar and salt need to be replaced in the body. In most cases, the treatment is given intravenously in order to not burden the inflamed gastrointestinal tract additionally. The World Health Organization (WHO) also recommends a saline solution and glucose solution, which is taken orally.

Cholera mainly occurs in poor countries and regions where water and sewerage systems are not separated. Pathogens evolve in contaminated drinking water. In unhygienic conditions the disease spreads quickly. The incubation period is very short - between three and six days.

Typhoid

Typhoid is an infectious disease that is characterized by high fever, abdominal pain and constipation. The fever also causes the heart rate to slow down. The pathogen is the typhoid bacterium "Salmonella enteric," which is usually transmitted if an infected person's feces contaminate the drinking water in poor hygiene conditions.

Three syringes. (Photo: picture alliance/ dpa)

The typhus vaccine affords a three-year protection

The incubation period is usually two weeks, but if many pathogens were ingested, it can be as short as one week. Typhoid patients initially feel tired and suffer from headaches and constipation. The fever rises until it reaches up to 41 degrees Celsius (105.8 degree Fahrenheit) after about eight days - and it can last for weeks. In addition to that, patients can slip in and out of consciousness and swelling of the spleen and a reddish spotty rash on the upper body can occur. The so-called typhoid tongue, which shows irritations and is covered in gray and white, is also typical. Doctors treat a typhoid infection with antibiotics. If left untreated, the disease can be fatal.

Leptospirosis

Leptospirosis is a bacterial fever, which is caused by the "Leptospira" pathogen. The bacteria multiply in warm-blooded animals, especially in rats, mice, pigs, dogs, cats, horses, sheep, goats and cattle. The animals excrete infected urine, which is how the bacteria get into the water. Humans become infected through contact with infected soil or water through small skin lesions. But the bacteria can also enter the body through healthy mucous membranes. The good news: a transfer from one person to another does not take place.

After the initial infection it may be a week or two - sometimes it takes up to 26 days - until the symptoms show. In most cases, Leptospirosis is similar to a flu. The patient suffers from fever, shivering, headache and body aches, but pinkeye and calf- and shin splints can also occur. This state lasts about three to seven days. It is followed by two to three days on which the patient is feeling better, before a second febrile phase begins.

A rat in nature. (Photo: https://www.flickr.com/photos/44080248@N03/5112493602)

Rats like this little fella transmit Leptospirosis

The usual treatment is penicillin, but this is only effective in the first five days of the illness. In the second phase of the disease antibiotics do not help because of an immune response. In that state, only the symptoms such as dehydration and fever are treated.

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