Q. What is leptospirosis? The Department of Health (DOH) recently announced that from the time typhoon Ondoy flooded much of Luzon more than two thousand cases (including more than 150 deaths) of the disease have been reported in Manila and Southern Luzon alone. Please write about leptospirosis so the public can become aware of this seldom heard of, but potentially, fatal disease.

-- Rolly F., Marikina City

A. Leptospirosis is an infectious disease that is caused by a bacteria, Leptospira interrogans. It is primarily an infection of lower animals such as cattle, pigs, horses, dogs, and rats and other rodents, but it can also affect humans.

In animals, leptospirosis is generally a mild disease, very few die from the infection but many serve as healthy carriers of the bacteria, which reside chiefly in the kidneys from where they are discharged and excreted with urine. Humans acquire the infection when they eat food or drink water that has been contaminated with the urine of infected animals; or, when their skin or mucous membranes (e.g., of the eyes or nose) get in contact with soil or water that is contaminated with infected animal urine. Human-to-human transmission of leptospirosis is extremely rare.

During the rainy season, outbreaks of leptospirosis are common because the rains wash off the leptospira bacteria from the surface of urine-contaminated soils. The bacteria then collect in floodwaters and people get infected with the microorganisms when they accidentally drink or wade in these floodwaters.

Leptospirosis also poses a danger to people who swim or wade in contaminated lakes and river, and to people whose jobs require them to get in contact with wet environment that has been contaminated with animal urine such as sewer workers, farmers, veterinarians, fisherfolks, or military personnel.

In humans, the signs and symptoms of leptospirosis appear two days to four weeks after exposure to the microorganisms.  Often, as in lower animals, the disease is simply characterized by mild and vague, flu-like symptoms that resolve spontaneously after a few days even without treatment. But in about 10 percent of cases, leptospirosis manifests as a severe and potentially fatal illness.

The symptoms of severe leptospirosis usually start abruptly and include high fever, headache, muscle aches especially of the calf, abdominal pain, nausea and vomiting, red eyes, and chills. Even if untreated, the patient usually recovers after about four to nine days. But occasionally, the apparent recovery period lasts only a few days and simply serves as a prelude to a second, more severe phase of the illness.

In the second phase, which is called Weil’s disease, the fever returns and the tissues in various organs and get inflamed resulting in numerous complications. Inflammation of the central nervous system can result in meningitis that manifests as stiff neck and disturbance in consciousness that can range from stupor to coma. Liver involvement results in yellowing or jaundice. Damage to the kidney can end up in kidney failure. Lung involvement can result in coughing up of blood and respiratory distress. Hemorrhages into skin and mucous membranes are also common. People who develop Weil’s disease require hospitalization, and even with treatment, one of 10 patients die.

The leptospirosis bacteria is very responsive to antibiotics such as doxycycline and penicillin, but to be most effective, antibiotic treatment should be started early in the disease. Doxycycline is also a very effective prophylaxis (i.e., preventive treatment) against leptospirosis that is why it is given to people who have been exposed to the same source as an infected person.

There is no leptospirosis vaccine for humans although there is one for domestic animals (dogs, for example). Nevertheless, the average person can prevent the disease by: refraining from wading or swimming in potentially contaminated water such as floodwaters; controlling the rodent population within his/her neighborhood by cleaning up rubbish and removing food sources that are close to housing; and, washing his/her hands with soap and water before eating. Incidentally, the leptospira bacteria are quickly killed by soap, disinfectants, and drying.

(E-mail inquiries on health matters to medical_notes@yahoo.com or wellbeing@mb.com.ph.)