Leptospirosis is an infection that is caused by a bacteria, Leptospirainterrogans. It is primarily an infection of lower animals such as cattle, pigs, horses, dogs, rats and other rodents. It affects humans only occasionally.In their animal hosts, the leptospira bacteria rarely cause symptomatic disease. Hence, these animals often serve as healthy carriers of the infection.
In animals, the leptospira bacteria reside chiefly in the kidneys from where they are discharged and excreted with the urine. Humans get infected with the bacteria when they swallow food or water, or when their skin or mucosal surfaces (e.g., of the eyes or nose) get in contact with water that has been contaminated with the urine of infected animals. As a rule, humans acquire the disease from animals. Human-to-human transmission of leptospirosis is extremely rare.
In water or moist environment, the leptospira bacteria can survive for many weeks, but they can not withstand dryness. Outbreaks of leptospirosis in humans are common during the rainy season 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 wade in these floodwaters.
Like in lower animals, leptospirosis is also usually only a benign illness in humans. In about 90 percent of cases, it presents as a mild disease that is characterized by vague, flu-like symptoms. But in the remaining cases, it manifests as a severe and potentially fatal illness.
The symptoms of leptospirosis appear two days to four weeks after exposure. They usually start abruptly and include high fever, headache, muscle aches especially of the calf, abdominal pain, nausea and vomiting, red eyes, and chills.
If untreated, the patient usually recovers after about four to nine days. But in some instances, 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 get inflamed resulting in a variety of 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.
Leptospirosis is occasionally fatal and people who develop the severe form of the disease require hospitalization. The bacteria are very responsive to antibiotics such as doxycycline and penicillin, but to be most effective, antibiotic treatment should be started early in the disease.
Recovery from severe leptospirosis infection is often a slow process that could last for weeks to months.
There is a leptospirosis vaccine for humans but it is not readily available in the Philippines. Nevertheless, the average person can avoid the disease by: refraining from wading or swimming in potentially contaminated water such as floodwaters; wearing protective clothing, including rubber boots, if one needs to wade in floodwaters; and controlling the rodent population within his/her neighborhood by cleaning up and removing food debris or garbage.
By EDUARDO GONZALES, MD