Understanding Leptospirosis: Causes, Symptoms, and Treatment

Understanding Leptospirosis: Causes, Symptoms, and Treatment

Leptospirosis is a disease that occurs in animals but can also be transmitted to humans. In such cases, one speaks of an anthropozoonosis. Leptospirosis often goes unnoticed, but the disease should not be underestimated because it can lead to death within a few days. Here, we explain how to recognize the symptoms and prevent infection.

What pathogen causes leptospirosis?

Leptospirosis is caused by spiral-shaped bacteria called spirochetes. There are numerous variants of the pathogen Leptospira interrogans, which can only be distinguished by antigen-antibody reactions in the serum (serovariants). The leptospira can still be divided into 21 species based on their genetic relationship. The other family of spirochetes also includes the pathogens that cause syphilis.

The disease occurs particularly frequently in humans after natural disasters in tropical and subtropical countries because the pathogens are at home in rats and mice and are excreted with their faeces and urine. The spirochetes can survive for months in warm, humid environments such as mud, puddles or brackish water.


Leptospirosis: how does it get infected?

The pathogens enter the body via minor skin and mucous membrane injuries. People can get leptospirosis from swimming, camping, or even boating.

But dog owners in this country are also familiar with the disease: To avoid infection with leptospirosis, dogs should not drink from puddles because, in our temperate latitudes, leptospirosis often occurs in spring and summer. The pathogens are susceptible to cold and cannot survive outdoors in winter.

Leptospirosis can occur more frequently in certain occupational groups, such as sewer workers, farmers, laboratory workers or veterinarians. In Germany, up to 166 cases of illness in humans have been reported in recent years, with a significantly higher number of unreported cases being assumed.

So far, an infection from person to person has only been documented in rare cases and is considered very unlikely.

Disease progression in two phases

Anyone suffering from leptospirosis does not necessarily have to become seriously ill. Overall, the symptoms of a leptospirosis infection can be very different. A mild course of the disease is just as possible as death occurring within a few days. In between, various disease courses are possible, in which different organs can be affected.

Leptospirosis often has two phases :

In the first phase  (acute phase), the pathogens can be detected in the blood and cause a high fever in the patient. This phase lasts about a week.

After the fever has subsided for the time being, in the second phase (immune phase), fever flares occur again, although they are not as severe and do not last as long as in the first phase. In the second phase of the disease, the pathogens can have established themselves in various organs and cause long-term effects there. Most complications occur during this phase.


Symptoms and forms of leptospirosis

The World Health Organization (WHO) has divided possible forms of illness into four groups, which is the global standard:

  1. A mild, flu-like form with fever (39 to 40 °C), chills, headache and body aches. Symptoms of conjunctivitis often appear.
  2. Weil disease (Morbus Weil): This form of leptospirosis shows severe liver and kidney involvement with jaundice, kidney failure, bleeding and myocarditis with abnormal heart rhythms.
  3. Severe meningitis or meningoencephalitis (inflammation of the meninges): Typical signs are a severe headache, sensitivity to light or a stiff neck.
  4. Bleeding in the lungs with respiratory failure: Such cases have been observed mainly during more significant epidemics and only rarely in isolated cases.

In humans, leptospirosis is mild in over 90 per cent of cases.

The incubation period averages 7 to 14 days (possibly 2 to 30).

Diagnosis of leptospirosis

To diagnose leptospirosis with certainty, either the pathogens must be detected directly (e.g. in the urine) or antibodies against the pathogens must be detected in the blood.

Antibody detection uses the MAT reaction (MAT = microagglutination test), which is considered the WHO standard method. With the MAT, the sera of the patients are diluted and mixed with live Leptospira strains. If antibodies are present, visible clumping of the leptospira occurs, which can be assessed under a microscope.

Further research is available to differentiate leptospirosis from other diseases that must be ruled out in the differential diagnosis. These include, among others:

Therapy: How is leptospirosis treated?

There is no uniform guideline for treating leptospirosis, but standard procedures exist. If the disease is detected early, it can be treated well with doxycycline, penicillin, ceftriaxone or cefotaxime.

In severe cases, methylprednisolone is sometimes used. If the kidneys are affected, dialysis may be needed.

If leptospirosis is detected directly or indirectly, the disease must be reported to the health department (it is therefore notifiable).


Prevention – what can you do?

To prevent leptospirosis, rats and mice must be controlled. It is also advisable for risk groups to wear appropriate protective clothing (e.g. gloves and goggles) to prevent contact with potentially infected animals and water bodies.

An active human vaccine is available in France but not approved in Germany.

Vaccination of your dog can also ensure that dog owners do not become infected with leptospirosis through their dog. Dogs usually receive vaccination protection with the primary immunization, which is refreshed with the annual leptospirosis vaccination.

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