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    Alarming rat fever outbreak

    November 11, 2019

    People who are involved in occupations such as farming, mining, or cleaning drains and canals, should inform your area MOH or PHI.A total of 4,160 patients suffering from leptospirosis (rat fever) were recorded during this year by November 8 (Friday). The highest number of patients (890) was reported from the Ratnapura district, the Epidemiology Unit sources said.

    According to the sources, an increased number of patients were observed during January, March and June. The highest number of patients (508) had been recorded in May. The number of patients reported from the Kalutara district is 528, while the Matara district recorded 420.In 2018, a total of 5,257 rat fever patients were reported from all parts of the country.

    Rat fever is an infectious disease caused by pathogenic bacteria called leptospires, which are maintained in nature in the kidneys of certain animals such as rats, pigs, cattle, rodents, canines, wild mammals and livestock. These organisms are transmitted directly or indirectly from animals to humans, consultant epidemiologists attached to the Epidemiology Unit of the Health, Nutrition and Indigenous Medicine Ministry said.

    According to the consultant epidemiologists, man is an incidental or accidental host of the bacteria. Exposure through water, soil, or foods contaminated by urine of affected animals is the most common route. A leptospire-contaminated environment caused by, for example, local agricultural practices (paddy cultivation) and poor housing and waste disposal gives rise to many sources of infection.

    Leptospires enter the body through abraded or traumatised (injured) skin or nasal, oral, or eye mucous membranes. Ingestion of contaminated water can also lead to infection. After infection, they enter the blood and invade practically all tissues and organs.

    The diagnosis of leptospirosis should be considered in any patient presenting with an abrupt onset of fever, chills, conjunctival suffusion, headache, muscle tenderness (notable in the calf and lumbar areas) and jaundice. The case fatality rate is reported to range from less than five percent to 30 percent, and important causes of death include renal failure, heart failure and widespread haemorrhage. Liver failure is rare despite the presence of jaundice.

    Knowledge of local epidemiology and varied clinical presentation, and high index of suspicion are essential to make a diagnosis. Suspicion should be further increased if there is a history of occupational or recreational exposure. Confirmatory diagnosis is mainly performed by detecting antibodies (e.g., MAT). However, simple investigations such as urine full report (albumin+) and the differential count of white blood cells (polymorpholeucocytosis) would help clinicians to make a probable diagnosis and also, to decide on the need for hospital admission. For epidemiological and public health reasons also, laboratory support is important. Identifying serovars (serotyping) is costly, time consuming and the results are not likely to affect treatment of an individual patient. However, the resulting information is useful in investigating its source or potential reservoir, and planning and evaluating interventions.

    Leptospirosis is a potentially serious but treatable disease.

    Treatment with effective antibiotics should be initiated as soon as the disease is suspected. Clinicians should never wait for the results of laboratory tests before starting treatment with antibiotics because serological tests do not become positive until about a week after the onset of illness, and the culture may not become positive for several weeks. Supportive care with strict attention to fluid and electrolyte balance is essential. Dialysis is indicated in renal failure. Heart failure can occur if medical treatment is not given on time.

    Serovar-specific antibodies produced following infection are protective and a patient is immune to re-infection with the same serovar as long as the specific antibody titre is high enough. However, it will not protect against infection with other serovars. The bacteria live in the environment over a period of one month.

    Preventive measures must be based on knowledge of high-risk groups and local epidemiological factors. It is important to raise awareness about the disease among the risk groups, healthcare providers and general population, so that the disease can be recognised early and treated as soon as possible. If you are involved in occupations such as farming, mining, or cleaning drains and canals, please inform your area MOH or PHI. They will explain the specific measures that can be taken to prevent contracting leptospirosis.



    Symptoms normally appear within five to 14 days following exposure to the germ. The range is between two to 30 days. Leptospirosis may present with a wide variety of clinical manifestations. These may range from a mild flu-like illness to a serious and sometimes fatal disease. It may also mimic many other diseases such as dengue fever, influenza, meningitis, and hepatitis. Jaundice is a relatively common symptom of leptospirosis, but is also found in many other diseases involving the liver.

    The main and common symptoms of rat fever are the abrupt onset of high fever, mild flu, chills, conjunctival suffusion, muscle tenderness (notable in the calf and lumbar areas), intense headache, jaundice and decrease in passing urine.


    In Sri Lanka, leptospirosis is reported throughout the year. High humidity and heavy rainfall intensify outbreaks because of widespread contamination by rodent urine in floodwater (rodents are displaced from their burrows and drains by the floodwater).

    Annually, there are two peaks in the disease incidence at the time of the monsoons, a smaller one during March–May and a larger one during October–December. This seasonal variability should be taken into consideration when planning prevention and control activities.

    Vulnerable people are farmers, persons who clean drains, persons who work in mines, marshlands, canals and persons who swim or play in contaminated water.


    According to Health Promotion Bureau sources, all information about leptospirosis and the drug (Doxycycline) used to prevent it and other details can be obtained by dialling the hotline 0710 107107. This free service is available 24 hours a day. Well-qualified doctors and consultants answer inquiries.



    * Remove rubbish and ensure areas around human habitations are free of rodents. Wild rats which live in the open environment are more dangerous than domestic rats.

    * Keep animals away from gardens, playgrounds, sandboxes, and other places where children play.

    * Wear protective clothing, knee-high boots, and gloves, and cover wounds with waterproof dressing where necessary.

    * Use boiled water (chlorination is seldom useful, as virulent organisms withstand up to four ppm; filtered water is also not safe).

    * Avoid walking in floodwater.

    * Doxycycline has been reported to give some protection against infection and disease. All vulnerable people in high-risk categories should contact the nearest PHI or MOH office and obtain Doxycycline tablets, which is issued free and they should take two tablets before they start work. They should drink plenty of water while working. The tablets give around 90 percent protection for a period of one week. Then they should take two tablets again, until they finish their work.

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