What is Leptospirosis?
Leptospirosis is an infectious disease caused by bacteria belonging to the genus Leptospira, and is transmitted directly or indirectly from animals to humans. Leptospirosis is a major direct zoonosis (an infectious disease that can be transmitted from nonhuman animals). Human-to-human transmission occurs only very rarely.
When does Leptospirosis usually occur?
Leptospirosis is endemic (native to a specific population) in many countries across the world. It often has a seasonal distribution, escalating with increased rainfall or higher temperature. However, the disease can occur throughout the year. The onslaught of Leptospirosis may be associated with changes in human behavior, water being contaminated by animals and/or sewage, changes in animal reservoir density, and natural disasters such as cyclones and floods.
What is the mode of transmission of Leptospirosis?
Human leptospiral infections result primarily from direct or indirect exposure to the urine of infected animals. Moisture is an important factor in the survival of the leptospires in the environment. Other modes of transmission of infection, such as handling infected animal tissues and ingestion of contaminated food and water, are also possible.
How do leptospires enter the bodies of humansand animals?
Leptospires can gain entry into humans through cuts and abrasions in the skin, through intact mucous membranes (nose, mouth, eyes), and perhapsthrough waterlogged skin. They may occasionally enter the human body via the inhalation of urine droplets or via drinking water.
Can leptospires be transmitted from human to human?
Yes, but rarely. They can be transmitted from human to human by sexual intercourse, transplacentally from a pregnant woman to the fetus, and via breast milk to a child. Urine from a patient suff ering from Leptospirosis should be considered infectious.As leptospires can be cultured from blood, blood should be viewed as infectious for some time before the onset of symptoms and during the fi rst 7–10 days of illness.
How does one know if he has Leptospirosis?
The clinical manifestations are highly variable. In general, the disease presents itself through four broad clinical categories:
• A mild, infl uenza-like illness
• Weil’s syndrome, which is characterized by jaundice (yellow discoloration of the skin), renal (kidney) failure,
hemorrhage or bleeding, and myocarditis (inflammation of the heart muscle) with arrythmias (abnormal heartbeat)
• Meningitis/ meningoencephalitis (infection or infl ammation of the brain)
• Pulmonary hemorrhage with respiratory Failure
How does the infection progress?
1. Incubation period (2-10 days)
Bacteria enter body through cuts or mucosal surfaces; bacterial fl agellae aid tissue penetration
2. Septicaemic phase (4-7 days)
Abrupt onset of fever, headache, muscle pain, nausea; leptospires isolated from the blood, cerebrospinal fl uid (fl uid from the brain and spine) and moist tissues; mostly anicteric (without jaundice), with only 5-10% with jaundice
3. Interphase (1-3 days)
Fever and other symptoms resolve temporarily prior to onset of immune phase
4. Immune phase (0-30 days)
Recurring fever and Cranial Nervous System involvement (meningitis).
How long is the incubation period?
The incubation period or the time of exposure/ infection, up to the time the disease manifests itself,usually lasts 7–10 days, with a range of 2–30 days.
When should physicians consider the diagnosis of Leptospirosis?
The diagnosis of Leptospirosis should be considered for any patient presenting an abrupt onset of fever, chills, redness of eyes, headache, muscular pain and yellow discoloration of the skin. The diagnosis is more diffi cult when patients present symptoms of cough, diffi culty in breathing, nausea, vomiting, abdominal pain, diarrhea, joint pains and a skin rash.
What is the case-fatality rate due to Leptospirosis?
Case-fatality rates in diff erent parts of the world have been reported to range from <5% to 70%. These fi gures are not very reliable, as in many areas the occurrence of the disease is not well-documented. In addition, mild cases of Leptospirosis may not be easily diagnosed. Major improvements in the prognosis of severe Leptospirosis have been made in recent decades, thanks to the use of hemodialysis as a means of supporting the reversible renal failure that may occur in some cases, and to aggressive supportive care.
How is Leptospirosis diagnosed?
The disease is usually diagnosed in the laboratory by detecting antibodies, (serodiagnosis), by culturing the bacteria from blood, urine or tissues, or by demonstrating the presence of leptospires in tissues using antibodies labeled with fl uorescent markers. Other methods may be available in some centers, e.g.the polymerase chain reaction (PCR) and (immuno) staining. The microscopic agglutination test (MAT) is the gold standard serologic test. MAT is only performed in reference labs and requires acute and convalescent samples for diagnostic confirmation, which means paired (2) serum samples are needed, which delays the diagnosis.
What is the optimal treatment for Leptospirosis?
Treatment with eff ective antibiotics or penicillin should be initiated as soon as the diagnosis of Leptospirosis is suspected and preferably before the fifth day after the onset of illness. The benefit of antibiotics or penicillin after the fi fth day of the disease is controversial. However, most clinicians treat with antibiotics regardless of when the onset of the illness began. Clinicians should never wait for the results of laboratory tests before starting treatment with antibiotics or penicillin. This is because serological tests do not become positive until about a week after the onset of illness, and cultures may not become positive for several weeks. In severe cases, admission to a hospital is necessary. Aggressive supportive care with strict attention to fluid and electrolyte balance is essential. Peritoneal or hemodialysis is indicated in renal failure. Mechanical ventilation is indicated for lung hemorrhagic manifestation. Excellent supportive care and dialysis have reduced the mortality due to this illness in recent years.
How can Leptospirosis be prevented andcontrolled?
The control of Leptospirosis is complicated and will depend on the local conditions. Control can be achieved by managing the reservoir or reducing infection in animal reservoir populations such as dogs or livestock. Control of wild animals may be difficult. Preventive measures must be based on knowledge of the groups at particular risk of infection and the local epidemiological factors. Prevention and control should be targeted at: (a) the infection source; (b) the route of transmission between the infection source and the human host; or (c) infection or disease in the human host.
How can the infection source be controlled?
It is important to establish what animal species are the infection sources in a particular area. Control measures can then be targeted on the local reservoir species of animals.
Such measures include:
• the reduction of certain animal reservoir populations, e.g. rats;
• the separation of animal reservoirs from human habitations by means of fences and screens;
• the immunization of dogs and livestock;
• the removal of rubbish and keeping areas around human habitations clean;
• encouraging people not to leave food around, especially in recreational areas where rats may be present.
How can transmission be interrupted?
Risk of infection is minimized by avoiding contact with animal urine, infected animals or an infected environment. Where appropriate, protective clothing should be worn and wounds covered with waterproof dressings to reduce the chance of infection if exposure is likely, e.g. occupational or recreational exposure.
How can humans be protected?
Much depends on detailed knowledge of how, where and when humans may become infected in a particular area. One possibility is to increase awareness of the disease among the population, risk groups and health care providers, so that the disease can be recognized and treated as soon as possible. Doxycycline has been reported to give some protection against infection and disease.
How can The Medical City help you?
At The Medical City, we have a complete roster of competent Infectious Disease and Renal Disease specialists who may assess or treat people with Leptospirosis.
HOSPITAL INFECTION CONTROL COMMITTEE
ER 2nd fl oor, The Medical City
Ortigas Avenue, Pasig City, Philippines
Tel. No: (632) 635-6789 ext. 6624/ 6625