Travellerís diarrhoea is one of the most common illnesses for tourists going to tropical climates. As many as 60% of all travellers suffer some form of diarrhoea, sometimes dubbed "Delhi Belly" or "Montezuma's revenge".
These can range from diarrhoea to nausea and vomiting and usually last about two or three days.
Patients usually self-treat, but experts say cases can be cleared up much quicker if sufferers take antibiotics.
About 10% of all cases are serious and people with long-term symptoms should seek specialist advice.
All patients with traveller's diarrhoea are advised to ensure they replace lost fluids with fluids and rehydration tablets.
Giardia and cryptosporidium are intestinal illnesses caused by the protozoan parasites affecting the gastrointestinal tract of humans and animals. They are shed in faeces and can remain dormant for long periods.
They are particularly difficult to remove from water systems.
Infections may be asymptomatic, or may cause diarrhoea, nausea, abdominal cramps, fever, vomiting and headaches. Most people will recover within several weeks, but individuals with weakened immune systems, such as HIV/AIDS or cancer patients, may be unable to remove the parasites from their systems and can suffer debilitating illness and even death.
Carefully wash your hands after toilet visits; dispose of sewage wastes carefully to avoid contaminating surface water or groundwater and ensure you never drink untreated water from spring, streams or lakes.
Typhoid and paratyphoid are also spread through contaminated water and food. They are recognised by the sudden onset of sustained fever, severe headache, nausea and severe loss of appetite.
There can be fatalities in 10% of cases, but this can be reduced to less than 1% with the right antibiotics.
There are about 17 million cases of typhoid each year globally and about 600,000 deaths.
Typhoid is transmitted by food and water contaminated by the faeces and urine of patients and carriers.
Polluted water is the most common source of typhoid. In addition shellfish taken from sewage contaminated beds and vegetables fertilized by faeces and then eaten raw are also sources of contamination.
There is a vaccine that can protect against typhoid, but it will not protect against paratyphoid.