Leptospirosis Advice Hurricane Katrina

The emerging natural disaster on the US Gulf Coast, centered on New Orleans, involves a large amount of flooding. In these situations there can be a risk of leptospirosis (Weil's Disease) caused by cross-contamination. As of 09/01/05, there are no confirmed cases.

The flooding of New Orleans originates from breaches in the Lake Pontchartrain Levees, and so flood water has a salt content similar to the lake. Leptospira cannot survive in salt water. Given the nature of the flooding from Hurricane Katrina, the LIC expects leptospirosis to be a small risk in the coming weeks. Also, evacuation plans currently in place will remove people from affected areas wherever possible, and Federal agencies are working to ensure safe and clean food and water is supplied to ALL residents.

The risks come from the urine of rats, displaced by floodwater and either forced into close proximity to humans, or direct contamination of food and water supplies by rat urine. Rat urine can carry the leptospira bacterum, and in approximately 25% of cases this can be a strain capable of causing illness in humans. The majority of human infections are mild, and resemble influenza. However in some cases the infection can be severe and life-threatening. There is no human vaccine available for the USA. The infection can also be contracted by dogs and livestock, however vaccination is commonplace for domestic pets, cattle and pigs. The illness in non-vaccinated animals is ooccasionally fatal, but primarily causes miscarriage.

There are many more likely infections present in the floodwater, caused by backflow from sewage, decay of animal matter and garbage. Leptospirosis is a distinct possibility given the presence of rats in the affected states, however the advice issued by FEMA and the CDC on how to remain safe and ensure food and water supplies are protected, will also deal with any risk from leptospirosis. As of 09/01/05 FEMA intends the total evacuation of flooded areas, which will of course limit any health hazards.

Leptospirosis has an incubation period of around 5 to 20 days, so we do not expect to see any cases for at least a week after a disaster. Symptoms are described in detail on the LIC website - the first signs are similar to influenza, with headaches, a skin rash, fever, muscle pains and nausea. In many cases the infection self-limits without treatment, but it may also develop into a fatal illness with multiple organ failure. Early treatment in hospital is effective in all but a few cases.

As there is no vaccine, control of infection after a disaster is based on antibiotics given prophylactically (as a preventative measure). This is only initiated if a confirmed outbreak is identified by the CDC as widespread use of the antibiotics can cause additional problems. Advice at this time remains the same as issued by the LIC and CDC for previous flooding events:

     * Avoid drinking floodwater, even by accident, or immersion of broken skin.
     * Avoid any food contaminated by floodwater, even if cooked. Sealed packages and cans may be used by sterilising the container before opening, using boiling water or bleach.
     * Minimise close contact with animals, including pets.
     * Be aware of any illness over the 3 to 4 weeks following exposure, and seek medical confirmation should you feel ill - especially if you notice a red skin rash accompanied by a fever or headache.
     * The risks from flooding are almost entirely due to direct contact with the water. Diseases common after natural disasters are rarely airborne and usually do not pass from human to human.
     * Ensure young children are supervised and aware of the health risks from floodwater.
     * Pay close attention to local advice on radio and TV and follow any instructions given. You will be advised of local issues regarding food and water .

The LIC is working in close collaboration with agencies in the USA and elsewhere, and will be updating our assessment and official advice as the situation emerges over time.

Leptospirosis Advice Hurricane Katrina

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Leptospirosis Advice Hurricane Katrina

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