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Intersectoral coordination and control measures

Notas Descriptivas: Leptospirosis

Photo Credits: W. Jirón

Measures for intervention and control of leptospirosis require the coordination of the public health, animal health and environmental authorities. The approach differs depending if there is an outbreak due to a natural disaster (flooding or heavy rainfall) that results in many human leptospirosis cases or if the situation concerns an endemic area where sporadic transmission occurs.

In the event of natural disasters it is important to save lives by providing timely medical care at the local level for suspected cases. A thorough field investigation is also required to identify which animal species are the source of infection, as well as survey the area to better understand the disease and possible prevention and control measures.

Given the large number of pathogenic serovars, numerous potential sources of infection, and variety of transmission conditions, the control of leptospirosis will involve a complex strategy that will depend on the local conditions. Raising awareness of the risk areas, risk groups for infection, as well as local drivers is essential when considering preventive measures.

  • Intervention at the source of infection (reservoir host/carrier):

      • Determine what animal species are the infection sources and direct control measures to target to the local reservoir
      • Separate animal reservoirs from human dwellings through fences and screens
      • Control animal hygiene and perform surveillance using serological diagnosis on a subset of the animal population
      • Immunize dogs and livestock annually
      • Establish rodent control (poisoning, trapping, avoiding access to food and drinking water, separation of human habitation)
      • Removing litter and maintaining cleanliness in the areas surrounding human dwellings; motivating people to not leave open food containers
      • Maintain cleanliness of areas surrounding human dwellings through the removal of litter and by motivating people to not leave open food containers
  • Intervention at the transmission route:

      • Risk of infection is minimized by avoiding contact with animal urine, infected animals or a contaminated environment
      • Transmission can be prevented by: wearing protective clothing; covering skin abrasions with waterproof dressings; washing or showering after exposure to urine splashes and contaminated soil or water; washing and cleaning wounds; developing awareness of potential risks and methods of preventing and minimizing exposure; providing clean drinking-water; avoiding bodies of water known or suspected to be contaminated (pools, rivers, lakes); establishing standard safety procedures for laboratories; introducing good herd management; disinfecting contaminated areas if feasible
  • Intervention at the level of the human host:

      • Raising awareness in the general population and at-risk groups; providing antibiotic prophylaxis in specific cases; providing immunization in countries where vaccines are available; educating physicians and the community; disseminating outbreak control information through press releases, radio and television announcements

:: Reference: WHO (pages 23-24; 37-40)

  • Laboratory testing for confirmation in animals:

  • Photo Credits: W. Jiron
    Notas Descriptivas: Leptospirosis
      • Serological testing (MAT, ELISA) is the laboratory method most frequently used to confirm clinical diagnosis, to determine herd prevalence and to conduct epidemiological studies
      • The microscopic agglutination test (MAT), the standard serological test, is used to diagnose individual animals and herds. The MAT is very useful for diagnosing acute infection in animals: a positive result is indicated by a four-fold or greater rise in antibody titer in paired acute and convalescent serum samples. To obtain useful information from a herd of animals, at least ten animals, or 10% of the herd, whichever is greater, should be tested and the vaccination history of the animals documented (tissue culture and body fluids included)
      • The enzyme-linked immunosorbent assay (ELISA) can also be useful for detection of antibodies against leptospires. Numerous assays have been developed and are primarily used for the detection of recent infections. Animals that have been vaccinated against the serovar of interest may be positive in some ELISA, thus complicating interpretation of the results.

    :: Reference: OIE (pages 251-255)

    •   Laboratory testing to identify circulating strains:

        • Typing of isolates may give an indication of the sources of infection and reservoirs, and thus determine the choice of methods for eventual prevention and control
        • A method that allows rapid typing of the most common isolates can be used to identify strains circulating in an area. Typing of uncommon and unusual strains should be sent to a reference center
        • Whatever typing method is used, comparison with reference strains will be needed. Local isolates may exhibit unique characteristics which differ from those of reference strains. Observation of differences between reference strains and local isolates is important, both from an epidemiological perspective and in defining the particular features that will enable local strains to be identified

    :: Reference: WHO (pages 19-20)

    • Identification of the agent and collection of samples in animals:

        • Leptospires in the internal organs and body fluids of clinically infected animals gives a definitive diagnosis of acute clinical disease. In the case of a fetus, leptospires in the above indicate chronic infection of the mother
        • Leptospires in the kidney, urine or genital tract of animals without clinical signs help determine the animal’s chronic carrier state
        • The identification of leptospires in the blood and milk of animals showing clinical signs is considered to be diagnostic. Isolation of leptospires from blood is not always successful because of the transient nature of bacteremia and the fact that it is not always accompanied by clinical signs. Identification of leptospires in blood is further diminished when the animal has been treated with antibiotics
        • The demonstration of leptospiral infection in organs taken at necropsy is diagnostic. If the animal has lived long enough or has been treated with antibiotics (thus making it more difficult to identify leptospires in necrotic organs), then immunohistochemistry can be particularly useful in identifying residual leptospiral antigen
        • Failing to demonstrate leptospires in the urine of an animal does not rule out the possibility of the animal being a chronic renal carrier

    :: Reference: OIE (pages 251-255)

    Communication and education

    Notas Descriptivas: Leptospirosis

    Photo Credits: O. Chávez

      • Both the medical community and the general public need to be informed of the risk of the disease, especially after a hurricane or flood since leptospirosis outbreaks are very common. For this reason there are risk communication guidelines (WHO: Outbreak Communication Planning Guide)
      • Physicians and health care providers should be informed about the symptoms of leptospirosis, risk factors, diagnostic testing and therapeutic strategies
      • Widespread community education can greatly assist in the identification of risk factors, prevention of illness, and reduction of the duration of the disease and its severity through early recognition of suspicious symptoms

      :: Reference: WHO (pages 39-40)

      References and links for Leptospirosis

      :: WHO: Human Leptospirosis: Guidance for Diagnosis, Surveillance and Control

      :: WHO: Report of the First Meeting of the Leptospirosis Burden Epidemiology Reference Group

      :: WHO: Report of the Second Meeting of the Leptospirosis Burden Epidemiology Reference Group

      :: FAO: Zoonosis en los sistemas de producción animal de las áreas urbanas y periurbanas de América Latina

      :: OIE: Leptospirosis Manual

      :: WHO: World Health Organization Outbreak Communication Planning Guide

      :: PAHO: Rodents in Disasters

      :: American Public Health Association (APHA): Control of Communicable Diseases Manual - 18th Edition. Washington, DC. 2004.

      :: OPS: Tratamiento de las Enfermedades Infecciosas 2011-2012, 5ª ed. Washington, DC. OPS. 2011.

      :: CDC: Emergency Preparedness and Response - Information for Clinical and Laboratory Support for Diagnosis, Management and Treatment of Leptospirosis in the Aftermath of a Disaster 

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            Last Updated on Wednesday, 14 January 2015 16:49

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