Distinguishing leptospirosis from dengue or a viral fever early on "can be clinically challenging because they all start with sudden fever, headache and generalised body aches," Dr Bashirat said.

One clue is redness of the eyes without pus, which can appear within the first three to four days, whereas dengue more often causes pain behind the eyes. Muscle pain also differs: severe and localised to the calves and lower back in leptospirosis, versus wider joint and bone pain in dengue.

Dr Deepak said the key giveaways are "severity of fever with chills, muscle aches and history of exposure to stagnant water."

He added that a fever developing "within a week" of rodent exposure should raise suspicion, especially if similar illness has been reported in the same neighbourhood.

Untreated, leptospirosis can move from mild fever and other symptoms to organ failure within three to seven days, and once severe complications begin, health "can deteriorate rapidly within 24 to 48 hours," Dr Bashirat said.

Dr Deepak pointed out that progression to a severe form can also happen around one week after fever onset.

Both doctors said absence of jaundice does not rule out leptospirosis. "Approximately 80% to 90% of symptomatic leptospirosis cases are anicteric, meaning they occur without jaundice," Dr Bashirat said.

Dr Deepak also said that the illness "can occur without jaundice" too, and both doctors urged patients seeking treatment to always disclose to their doctor recent exposure to floodwater, mud, rodents, or a stay in a house that had been shut up for a long time.

Dr Deepak called this "a vital piece of history," especially for expats who fall ill after returning to the Gulf.

Dr Deepak flagged a specific risk for expats returning home for the holidays. In houses left locked for months, "rats are a major source of leptospira breeding," he pointed out.

Before entering or cleaning such a home or dealing with rat infestation on the premises, he advised covering cuts or scratches with waterproof dressings, wearing rubber gloves and enclosed waterproof footwear, avoiding bare-skin contact with dust or droppings, ventilating the space before cleaning, and never touching rodents or droppings with bare hands.

Dead rodents or droppings should be cleared with a shovel or gloves, the area sprayed with a disinfectant such as bleach, and hands and skin washed thoroughly with soap afterwards, the doctors said.

Experts also flag one overlooked household habit: drowning trapped rats in buckets of water. Leptospira bacteria shed in rat urine can contaminate that water, and if it touches a cut, scrape or even a fresh nail-clipping wound, infection can follow.

Since symptoms typically take five to 14 days, and up to 30, to appear, the link to this everyday chore is easily missed.

Doctors advised avoiding bare-handed contact with such water contaminated with rat body fluids, and keeping wounds covered.

Dr Deepak said the risk from contaminated water or mud can persist for two to four weeks after water recedes in areas flooded during rainy season.

She recommended avoiding waterlogged areas, wearing protective clothing, and pursuing rodent eradication at home with proper precautions.

Dr Bashirat added that food should be kept in sealed, rodent-proof containers, drinking water treated or boiled during flooding, and a thorough shower taken with soap after any contact with floodwater, mud or contaminated surfaces.