Overview of human leptospirosis - guide for the public

[Guest guest]

_http://www.leptospihttp://wwwhttp://wwwhttp_

(http://www.leptospirosis.org/topic.php?t=30)

 

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 persistent infection which are almost impossible to treat.

 

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.

 

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.

 

 

 

[Guest guest]

Does anyone know of a case of lepto where pet rats were concerned? I am

talking about the ones sold as pets and have been bred from the original

lab rats generations ago. I have a few pet ratties and know of a lot of

people who also have rats as pets. Just wondering if pet rats, not

being exposed to any wild ones, would be carriers?

 

Angls4Hope wrote:

>

>

>

> _http://www.leptospihttp://wwwhttp://wwwhttp_

> <http://www.leptospihttp://wwwhttp://wwwhttp_>

> (http://www.leptospirosis.org/topic.php?t=30

> <http://www.leptospirosis.org/topic.php?t=30>)

>

> 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.

>