According to data from Public Health Surveillance in New Zealandthere were 12 cases of leptospirosis (9 confirmed and 3 under investigation) notified in May 2022, compared to 7 cases for the same month in 2021. The 9 confirmed cases were aged between 25 and 70, 8 were men and 1 was a woman. Seven confirmed cases reported exposure to animals (4 due to the nature of their farming profession) and 4 had contact with streams, rivers or lakes.
Six confirmed cases (85.7%) were hospitalized. The strain serovar Leptospira has been identified for 4 confirmed cases; 2 Leptospira Hardjo1 Leptospira Ballum et 1 Lesptospira Copenhagen.
Reminders on the leptospirosis.
The leptospirosis is a worldwide bacterial disease. Leptospirosis is caused by bacteria Leptospira interrogans. This is quite easily maintained in the external environment (fresh water, muddy soils), which promotes contamination. The seasonality of the disease is very marked, with a summer-autumn upsurge linked to heat and rainfall.
bacteria of the genus Leptospira are likely to infect a large number of wild mammals (rodents and insectivores: rats, tengues, shrews, etc.) and domestic ones (cattle, sheep, goats, pigs, dogs), which act as reservoirs and excrete them in their urine. Bacteria can survive for several months in a humid and warm environment. There are over 250 serovars of Leptospira species, with several serovars endemic to a given geographic area.
Certain professions (farmers, breeders, sewer workers, garbage collectors, etc.) and people practicing water sports (swimming, canoeing, kayaking, fishing, hunting, canyoning, etc.) are particularly at risk. In humans, the bacterium penetrates mainly through injured skin or mucous membranes.
The disease is often mild but complications are possible, including kidney failure which can lead to death in 5 to 20% of cases. The incubation of the disease lasts from 4 to 14 days.
- In the moderate form, the disease begins with a high fever with chills, headaches, muscle aches and diffuse joint pain. In 20% of cases, it is complicated by a hemorrhagic syndrome.
- Severe forms (icterohaemorrhagic or Weil’s disease) combine acute renal failure, neurological impairment (convulsions, coma) and more or less severe bleeding (pulmonary, digestive).
The initial non-specific clinical signs (headaches, fever, myalgia) can lead to a diagnostic and therapeutic delay by confusion with differential diagnoses such as influenza, chikungunya or dengue fever.
Prevention and individual protection measures against leptospirosis:
- Avoid bathing in fresh water, especially when you have wounds, and when the water is cloudy or muddy;
- Avoid contact with water, nose, mouth and eyes;
- Avoid walking barefoot or in open sandals on muddy ground, in puddles, stagnant water, ravines (especially in overseas departments);
- Protect wounds from contact with water with waterproof dressings;
- Wear protective equipment during high-risk professional activities (breeding, sewer workers, garbage collectors, farmers, working the land, etc.) including boots, gloves, waders, protective clothing, or even anti-splash goggles in the event of a risk of projection ; the practice of white water sports such as canyoning, kayaking, including a protective suit, boots and gloves.
- Control rodents, which are the reservoir of the disease.
After a risk exposure:
- Wash with drinking water and disinfect the wounds;
- Consult a doctor without delay in the event of the appearance of symptoms, informing him of the risky activity carried out in the previous two weeks.
These measures are to be reinforced during the rainy season.
There is a vaccination against leptospirosis. Its effectiveness being limited to certain strains of leptospira, it is rarely carried out in practice, mainly concerning professionals.
Source : Public Health Surveillance, New Zealand Ministry of Health.