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 What is Weil's Disease (Leptospirosis)

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PostSubject: What is Weil's Disease (Leptospirosis)   Fri Jun 11, 2010 7:50 pm

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What is Weil's Disease (Leptospirosis)



Immediate action following exposure

The first thing to say is that infection is far from certain, even when the exposure was from a high-risk source. Unless you are already feeling unwell, you have plenty of time to seek help. Even people in the early stages of illness respond extremely well to antibiotics.

1 - Early recognition of exposure
2 - Early use of antibiotics
3 - Early blood testing


1. The most important factor in saving lives is to recognise the risks, so if you are accidentally exposed to something you believe to be contaminated you can seek help without delay. The incubation period is at least 3 days so you have time to visit your doctor if you know it's necessary!

2. Antibiotics are very effective if given early in the infection, but less so in later days and weeks - so getting antibiotics as soon as possible is also important.

3. Finally, your doctor needs to confirm if you actually have been infected or not - and for that they will need to take a blood sample, sometimes two. As the illness is so general in symptoms, without a test there is no way to tell what bacteria or viruses you may have picked up.



If the exposure happened recently and you do not feel ill:-

For unlikely events where the chances of infection are low (such as splashes on unbroken skin), we advise you to simply wait and watch for any illness. We know this sounds stupid, but antibiotics given in the first few days of illness are very effective, and unless there is a reasonable chance they are needed, the side effects and potential for resistance outweigh the benefits.

If the risk exposure was high (immersion in contaminated water, splashes on broken skin, drinking contaminated water, etc.) then you should contact your local doctor and request a single dose of antibiotics - called a prophylactic dose, details below - which will usually prevent any illness from developing. Your doctor may also decide to take a blood sample, but they will often need to wait about 24 hours from the exposure event in order to get measurable levels of the bacteria in your blood.


If you have started to feel unwell:-

Of course the most important advice is to go and see your doctor if you start to feel unwell. Early symptoms resemble a cold or flu, with a fever, headaches and often a red pinpoint skin rash - the detailed symptoms are described in the link below. Remember also that water contaminated with leptospires is possibly contaminated with other harmful bacteria and chemicals, and your illness may be caused by any one of them - without a blood test even a specialist doctor will find it hard to tell just from the symptoms.

In every case where someone has a 'risk exposure' and then shows compatible illness within the incubation period (4 to 21 days), a blood test for leptospirosis should be ordered and a program of antibiotics started - waiting for the test results is not a good idea, as in many cases it can take over two weeks for the results to come back. Note that in more severe infections the patient will seem to recover slightly after the first few days, but then rapidly become seriously ill. Mild cases will often self-limit and the patient recover without medical help, but it can be difficult to predict how each case will develop so the same testing and medication are advised for all cases in the first few days of illness.

When you visit your doctor, explain what you were doing and what you think you have been exposed to. If you say "Doctor, I went swimming and now I have a fever and a headache" you will most likely be given painkillers and sent home with a suspected case of the flu, or sinusitis. If you say "Doctor, I went swimming in dirty water. I've heard of people getting a nasty illness from rats and I'm worried I've got it" then you'll prompt your doctor into ordering the right blood tests without putting their nose out of joint. Many doctors have never seen a case of leptospirosis and may not associate it with your symptoms. However, they also may not like you arriving and quoting medical terms at them like you're a consultant bacteriologist. If you're not getting anywhere, then you can resort to helping them towards a diagnosis a bit more forcibly.


Important notes for children

Young children are often exposed to leptospira during play, and while they are no more or less likely to be infected than an adult, parents can often miss the early symptoms, passing it off as a common flu or cold. Antibiotic treatment is also different in children, so parents are advised to seek medical advice if they are unsure as to the chances of infection or causes of an illness. More details are given in the topic links below.


Causes of infection - guide for the public

Human infection is always caused by exposure to the bacteria that have been shed by an infected animal, and in 90% of cases it will be their urine (although infection direct from blood is also possible). Direct transfer, where the urine comes into contact with the patient and enters their bloodstream, is very rare except in accidental exposure when handling infected animals, and the usual route is via water that is subsequently drink, or used for recreation such as swimming.

The bacteria have to physcially enter your bloodstream in order to cause an infection, and as they cannot easily penetrate dry undamaged skin, they can only enter at certain locations - injuries where the skin is broken are the obvious places, but mucous membranes lining the airway, mouth, lungs and female sexual organs are also potential routes - so breathing in or swallowing bacteria is a risk, and leptospirosis can sometimes be spread via sexual intercourse.

Dry unbroken skin is a perfect barrier against the bacteria, but cuts and scrapes need only be tiny for the bacteria to find an entry point. There is also a suggestion that the bacteria can pass through very waterlogged skin (such as when skin is immersed in water for a long time), as the cellular structure of the skin changes slightly. This is still only a theory and we have no cases on file.

The bacteria are not generally airborne, so the only risks for breathing in the infection are where water droplets are being created - such as pressure-washing work or in the spray chambers of some air conditioning plant. Being "generally close" to an infected person or animal will not cause an infection!

It's important to realize that the bacteria are incredibly small, and so even a pinhead sized drop of water can carry millions of them. In theory it only takes one to cause illness, but in reality your body's immune system will attack them to a certain extent and so the chances of illness increase as the volume that enters the body (the 'innoculum') increases.


What are the chances of catching this infection from my local river/pond/cess pit?

Obviously this depends on two things - if the water is infected with the bacteria, and if you and said bacteria get in close enough contact!

On average in the developed world (Europe, mainland USA, etc.) about 20% of feral rats carry strains of leptospira that could cause illness in humans. This of course varies locally - in your area you may have 100% rat carriers, or 0% - it just depends on the social lives of the rats in question. It's therefore sensible to assume that on average 10% of all freshwater sites are infectious, with more probability for sites which stand good chances of hosting rats nearby (urban ponds, slow-moving rivers and canals, lakes near farm buildings, etc.) and less of a risk for non-rodent-friendly sites such as rapid flowing highland streams or very large estuaries and river deltas. Obviously any site with a high water throughput (such as a river) is less of a risk than stagnant water, as rodent urine will be diluted by the flow. Any water treated with chlorine or UV-sterilisation will be totally safe. This means that swimming pools, and many municipal water fountains and architectural features, are usually of no risk in terms of leptospirosis.

The chances that being exposed to contaminated water would lead to infection depends on what you do in the water. To become infected you must actually allow water to enter your body, though that could be as simple as through an open cut, or by licking a finger. Swimming is the highest risk activity as there is no way to prevent some ingestion and skin contact, though other activities such as fishing, waterskiing, sailing and kayaking can also present risk. Remember that the bacteria cannot survive in saltwater so there is no possible risk from swimming in the sea, or in tidal regions of rivers where the water is briny.

In general in the developed world people are wary of open water sites from general cleanliness viewpoints, and would not drink from a lake without a very good reason. The chances of infection are therefore quite low, but these statistics hide the fact that in many cases the infection is mild, and goes unreported. Despite only a few thousand cases being reported in the developed world each year, there will be many times more cases which are simply written off as a cold or stomach bug - we estimate the total number of cases in the developed world could be up to 100,000 per year.

In developing countries the risks are greater, as rat populations are more widespread and water use is different. The quantity of untreated water used for washing, bathing and drinking is far higher, and the association between hygiene risks and open water is rarely made. Education in developing countries is the only solution to this issue, as the bacteria and the rats are there to stay.


Overview of human leptospirosis - guide for the public

Human leptospirosis can be a difficult infection to describe, as the symptoms can vary dramatically between patients. Some symptoms are extremely common, but only a small number of patients will experience the severe life-threatening illness known as Weil's disease. The severity of the infection depends on the age and general health of the patient, plus the serovar (strain) of bacteria involved and the number of bacteria that entered the patient's body.

The infection is usually systemic (affecting the whole body) and causes a sudden fever. In mild cases it lasts a few days, following a pattern similar to flu but often in two phases - a period of illness lasting a few days, then a slight recovery, then a second period of illness. In mild cases the second phase lasts a short time and the patient recovers, but in severe types the illness develops and progresses rapidly, leading to organ failure and often death if not treated with intervention and support.


Incubation time

From the time you were infected with the bacteria, there is a period where it has to reproduce enough to cause illness - called the 'incubation time'. With human leptospirosis this is typically 3 to 21 days, with most patients developing illness after about 3 to 14 days. It does not usually take more than 28 days, but in rare cases very long incubation periods have been reported. It generally cannot show illness in less than 24 hours unless the volume of bacteria taken into the bloodstream was massively larger than normal.
First stage

Leptospirosis starts suddenly, with a severe headache, redness in the eyes, muscle pains, fatigue and nausea and a fever of 39°C (102°F) or above. There is sometimes a red non-blanching pinprick rash on the skin, similar to that seen in meningitis. Young children can be tired or distressed and may show an aversion to bright light. The severe headache is almost always present and can be incapacitating. Nausea may or may not cause vomiting. Muscle pains can be extreme and are often particularly bad in the calf and back areas - muscles will be sore to move and to touch. A rapid pulse is also common in the first few days.

The skin rash develops in the first one or two days and often the skin is warm and pink just beforehand, with the patient complaining of feeling warm. Rashes can occur anywhere but in some cases are confined to local regions of skin such as the front of the legs. Sometimes they will be itchy, but rashes are only seen in about 30% of all cases so the lack of any rash is not too significant.

Psychological changes are often seen, with patients feeling depressed, confused, aggressive and sometimes psychotic - with schizophrenia and hallucinations, personality changes and violence.

This phase lasts between three and five days, then the patient (temporarily) recovers. During this phase the bacteria are active in the patient's bloodstream (so it is sometimes called the septecaemic phase) and so can be detected by lab tests.


Second stage

In many mild cases this doesn't happen at all, but where the infection is more severe, the patient enters a second phase of illness after a few days of apprent recovery. The initial symptoms and fever return, accompanied with chest and abdominal pain, some renal problems and psychological changes. Increased symptoms of meningitis are often seen with neck stiffness and vomiting, but in most mild cases the patient will not suffer kidney or liver failure and will eventually recover. There may be a sore throat and dry cough, with a litle blood. With treatment, mild cases will recover within a few weeks.

During this second phase the bacteria are only really active in the tissues of the patient, and so can be difficult to find in the bloodstream, making lab tests a problem. This second phase is usually called the 'tissue' or 'immune' phase.


Severe infections

In cases of particularly virulent serovars or patients with poor health, the infection follows a different pattern and the patient develops very rapid and severe symptoms from the start, without much of a remission. Symptoms are the same as for the mild type but more pronounced, and multiple organs are damaged - liver and kidney failure can occur within 10 days, leading to jaundice and death if not treated. Hemorrhages are common (including bleeding from the mouth, eyes and other mucous membranes), plus infection of the heart and significant internal bleeding. Dialysis is the most important intervention and the patient will require antibiotics and hospital admission in order to stand a chance of survival. Death, when it occurs, is usually due to heart, liver or respiratory failure. Severe infections are often called 'icteric' because of the presence of jaundice, and these are the only cases that can really be called Weil's disease.


Recovery

Patients with mild infections recover quite quickly, so are usually feeling OK after a few weeks, but they can suffer from fatigue and depression for a while and may be at risk from persistent infection. Patients with the more severe infections can take several weeks to recover, as removing the bacteria is not the problem - they will have caused damage to the body's tissues that take time to heal. Although some patients can die, with medical treatment the chances of survival are good - though patients that have had a severe illness may suffer long-term symptoms due to organ damage that cannot completely heal. Psychological changes (mood swings, depression, psychoses) are common for a few months following recovery.


Immunity

Patients that survive infection will develop some immunity, but only to the serovar that infected them and some closely-related ones. They can still be infected by other strains, and the immunity lasts no more than ten years in humans. There is a very small possibility of auto-immune reactions to the bacteria if patients are reinfected again, but the main concern of patients is that they can suffer from medium-term symptoms due to persisistent infection which are almost impossible to treat.


Treatment of human leptospirosis - guide for the public

Treatment for acute illness in humans is in two parts - an antibiotic to control the bacteria and general support of the patient's internal organs so they maintain their ability to recover while the bacteria are removed.


Antibiotics

Leptospirosis can be treated by a wide range of antibiotics, and medical staff will select the best based on availability, the patient's age and any other medications they may be taking. In mild cases the medication will be given by mouth adn the patient can stay at home, but in severe infections the antibiotics are often given directly into the bloodstream via a drip (IV) and so require them to remain in hospital. This is also important to allow them to be monitored as the infection progresses.

In many cases, penicillin is used - but if the patient is allergic then a number of alternatives are available as well. It is very important to take antibiotics as prescribed - do not miss any doses and take all the doses even if you feel that you've recovered. Stopping a course of antibiotics before the end can lead to resistant bacteria taking hold and causing very severe illness. The dose of antibiotic will be calculated based on the patient's age and body mass, and medical staff do not need to know the exact strain of leptospira involved before beginning treatment - indeed it should be started before test results are returned if the patient has a high probability of being infected.


Other medications

Often patients will have severe headaches, fever and nausea in the first week or two, and these can be controlled by normal non-prescription medicines. In some cases medical staff may prescribe additional programs of medication to help with liver or kidney function, or to support deficiencies in diet.


Hospital care

In severe infections the patient will be admitted to hospital, and may need to be intensively supported for a few weeks. Patients can require dialysis, fluids and painkillers plus help with their breathing. In very rare cases patients can become psychologically disturbed and may need sedation for their own safety. The infection is not particularly contagious and so patients are not usually isolated and can receive visitors as their condition permits.


General recovery

Recovery can take a while, and a lot of patients find they suffer from fatigue and depression for a few months after recovery, requiring support. Maintaining a healthy diet with all the proper vitamins and minerals is very important during recovery, and patients that feel fatigued should rest as much as they need to - fighting it off and continuing to work can make recovery a lot slower.


Persistent human leptospirosis - guide for the public

Persistent infection is a situation where the patient has recovered from an acute illness, but shows some long-term health effects caused by the bacteria remaining in isolated areas of the body, long after the immune system has removed them from the bloodstream and general tissues. It is different from a carrier state as the patient is not infectious to others, but persistent human leptospirosis (PHL) is far more common than previously thought.

These long-term issues are not only a factor of leptospirosis - other infections from bacteria in the same order, such as Lyme disease, often show health problems for several years after recovery.


Symptoms of PHL

Symptoms vary a great deal between patients, with some being almost incapacitated and others noticing nothing. The reported symptoms are listed below, with the most common first:-

1. Depression, from mild personality changes to quite severe clinical disorders and suicides.
2. Fatigue, often quite pronounced and debilitating
3. Headaches, resembling migraines but not always particularly severe.
4. Eye pain, with or without any inflammation, sometimes with vision disturbances.
5. Psychological changes, including mood swings, short tempers, rarely OCD.
6. PIEM, parainfectious encephalomyelitis, is seen in quite a few cases. This is damage to the nervous system and manifests in different ways, so patients can show symptoms of meningitis, epilepsy, balance problems, muscle weakness and vision disturbance. It can mimic the symptoms of multiple sclerosis.



Causes of PHL

There are two reasons for ill health following a bacterial infection:-

Tissue damage

During the acute illness, bacteria cause damage to tissues in the patient's body, by a combination of toxins and damage to the blood supply. This can lead to long-term changes in the function of internal organs but is not directly related to the bacteria, only to the damage they cause. Reduction in function of the liver and kidneys is one such outcome, but where the tissue damage is not too severe the body will heal over time.


Bacterial residency

In the body there are certain places, called immunologically privileged sites (IPSs) where the immune system is not very active, and bacteria can survive long after they have been killed in the rest of the body. These sites are usually places without a direct blood supply, such as the fluids within the eyeball and the structures of the brain and nervous system. In the rest of the body, the patient's immune system reacts to leptospires and creates antibodies that will ensure they are killed within a few days, however in IPSs the supply of these antibodies, and the white blood cells that do the killing, are reduced. Bacteria can 'hide' in these sites but are kept trapped by the active immune system, so the symptoms tend to be concentrated on the same organs. We have very little direct evidence for the time bacteria can survive in this way, but it is certainly several months or years.

While they are present, leptospires in IPSs have two effects - they still leak toxins into the tissues, albeit at a quite low level, and this can cause slight inflammation or reduction in tissue viabililty. More importantly they can continually trigger the immune system at the border of the IPS, and the immune response to this constant prodding of white blood cells can be more severe than is required - in some cases it will cause an autoimmune response where the body's immune system starts to attack 'self'. It's common for patients with PHL to show unexpected severe symptoms when exposed to leptospires a second time, as the autoimmune response is activated. It's particularly true in the eyes and is the cause of recurrent symptoms in horses.


Treatment

There is no working treatment for PHL at this time which has shown itself to be effective on every patient - research conducted in recent years has shown promise in developing an immunological treatment program, however in the majority of cases supportive care is given. Maintaining a healthy diet with full nutritional balance is very important, and symptoms can be treated in isolation (with painkillers, etc.) but in many cases a repeat program of antibiotics has been able to increase the speed of recovery. The difficulty is that medication will only act on the persistent bacteria, and so any long-term tissue damage caused by the infection will need to heal at a natural rate - this can take several years and in severe infections there can be some permanent damage to tissues. Patients suffering poor helth after a leptospirosis infection should always discuss the issue of PHL with their physician, if necessary via a referral to a specialist in infectious and autoimmune disease. The symptoms are expected to reduce over time even without treatment, and so in many patients with only minor reduction in health it can simply be a waiting game.





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