North Kerala has been put on high alert after an 11-year-old boy died and 20 suspected cases of shigella bacterial infection were reported in Kozhikode on Saturday, district medical officer Dr Jayashree said.

She said the death took place two days back and later 20 people with symptoms, mild diaorrhea and fever, were admitted in various hospitals. Most of the infected were people who came in direct contact with the deceased.

State health minister K K Shailaja said the health department will conduct a health camp in the area in a couple of days and investigation is on to locate the main source of the infection. She said health experts have said the infection spread through water and food and keeping good hygiene was the primary way to check the spread.

Worried health authorities have super chlorinated all water bodies in the area on Friday. Last year over 40 children of the West Lower Primary School, Keezhppayyur, were hospitalised after they complained of vomiting and diaorrhea. The presence of shigella bacteria was confirmed in the stool samples of at least two of these students, who recovered later. Later the district health department traced the presence of the bacteria from the water body in the siblings’ house.

According to health experts, shigellosis is an infectious disease caused by the shigella bacteria, which triggers stomach pain, diaorrhea and fever in those infected. Though a worldwide problem, shigella is more often seen in developing countries, especially in crowded locations such as schools, day care centres, nursing homes or regions with poor sanitation. In some cases, people infected with the shigella bacteria do not have symptoms, but are still contagious.

Besides water, there is a possibility that the bacteria spread through contaminated food, though the chances of that are less in this case, said officials. The health department has directed the community medicine department to reinvestigate each case and submit a report at the earliest.

Health experts said the infection is not that deadly but if it is ignored it will aggravate the health condition and the patient may die of dehydration and exhaustion. But if ignored it may pose serious problems. “It has already been diagnosed. It is not a serious threat. We have to maintain personal hygiene,” said Dr C Anoop Kumar, head of the critical care unit in Baby Memorial hospital in Kozhikode. He was one among the first to diagnose the Nipah virus two years ago

The deadly Nipah virus cases were reported in the district two years ago but it was localized and contained effectively though it claimed 17 lives.