When it rains, it pours. Given that we are already in the rainy season, we anticipate an increase in rainfall.
In areas where rats are prevalent, the primary health risk that individuals may face is leptospirosis, a serious infection that can be life-threatening if not treated early. This water-borne illness tends to be more prevalent following flooding in an area.
From January to May 2025, there has been a notable increase in leptospirosis cases in Davao City, with 94 reported cases and 23 deaths. With the rainy season and flooding every now and then, the cases and death are most likely to increase.
Leptospirosis was first described by Adolf Weil in 1886. Leptospira, a corkscrew-shaped bacterium that caused the disease, was first observed in 1907 but it was the following year that it was declared as the cause of it.
Several species of the Leptospira genus of bacteria cause leptospirosis. It can progress to conditions such as Weil’s disease or meningitis (inflammation of the protective membranes covering the brain and spinal cord), which can be fatal.
The Geneva-based World Health Organization (WHO) says the bacterial infection is prevalent in tropical countries, where it affects 10 or more people every 100,000 annually.
“Leptospirosis occurs in many wild and domestic animals,” explains The Merck Manual of Medical Information. “Some animals act as carriers and pass the bacteria in their urine; others become ill and die.”
The health department says many animals can spread leptospirosis, including pets (dogs, for example), farm animals, or wildlife. Aside from rats, the animals that can spread leptospirosis are cattle, swine, horses, sheep, and goats.
Actually, there are two common ways you can get leptospirosis. First is by exposing yourself to urine or body fluids of infected animals. The other one is by drinking water or contacting soil that has been contaminated with urine or body fluids of infected animals.
According to the health department, the leptospirosis bacteria enter the human body through cuts and cracks on the skin, or through membranes of the eyes, nose and mouth. Once in the bloodstream, the bacteria can reach all parts of the body and cause signs and symptoms of illness.
Studies conducted abroad have shown that leptospirosis causes mild disease in about 90% of infected people, whereas 10% have severe, potentially fatal, disease that affects many organs.
There are two phases of leptospirosis. “The first phase starts two to 20 days after infection with Leptospira,” the Merck manual informs. “Symptoms begin abruptly with a fever, headache, severe muscle aches, and chills. The eyes usually become red on the third or fourth day. Nausea and vomiting are common.”
Symptoms involving the lungs (including coughing up of blood) occur in 10 to 15 percent of infected people, studies reveal. Episodes of chills and fever, which often reaches 102 degrees Fahrenheit, continue for four to nine days.
The fever clears for a few days, marking the beginning of the second phase. “During the second phase,” the Merck manual informs, “the body’s immune reaction against the bacteria causes inflammation, producing many symptoms. The fever returns, and there is often inflammation of the tissues covering the brain (meningitis), causing a stiff neck, headache, and sometimes stupor and coma.”
According to Medical News Today’s Yvette Brazier, symptoms depend on which vital organs are involved. It can lead to kidney or liver failure, respiratory distress, and meningitis. If it affects the heart, liver and kidneys, the person will experience the following:
Fatigue, irregular – often fast – heartbeat, muscle pains, nausea, nosebleeds, panting, poor appetite, swelling of the hands, feet or ankles, unexplained weight loss, and jaundice, seen in a yellowing of the white of the eyes, tongue and skin.
If leptospirosis affects the brain or spinal cord, the signs and symptoms may include: confusion or disorientation, drowsiness, fits or seizures, high fever, nausea, photophobia (sensitivity to light), problems with physical movements, stiff neck, inability to speak, vomiting, and aggressive or unusual behavior.
If the lungs are affected, the signs and symptoms are high fever, panting, and coughing up blood.
Leptospirosis is not spread from human to human, the health department says. If you are either residing in a flooded area or has high-risk exposure (wading in flood waters, swimming in flood water or ingestion of contaminated water with or without cuts or wounds), DOH suggests that you should see a doctor immediately.
“Early recognition and treatment within two days of illness to prevent complications of leptospirosis, so early consultation is advised,” the health department urges.
Only a doctor can confirm the diagnosis of leptospirosis. The doctor does this by identifying Leptospira in cultures of blood, urine, or cerebrospinal fluid samples or, more commonly, by detecting antibodies against the bacteria in the blood.
“Once your doctor has confirmed that your symptoms are that of leptospirosis and by doing a test,” the health department states, “you should be treated with antibiotics. Treatment is most effective when started as soon as possible.”
If you have traversed floodwater even a single time, here is the advice from experts: Doxycycline 100 mg (2 tablets within 24 hours), Azithromycin (10 mg/kg as a single dose, maximum 500 mg), and Amoxicillin (50 mg/kg/day, administered every 6 hours for 3–5 days, with a maximum of 500 mg per dose). Be sure to talk with your doctor first before taking any of these medicines.
If the exposure occurred more than seven days ago, experts recommend that you should repeat the medication after one week.
