Leptospirosis
Leptospirosis is a blood infection caused by the bacteria Leptospira that can infect humans, dogs, rodents and many other wild and domesticated animals. Signs and symptoms can range from none to mild (headaches, muscle pains, and fevers) to severe (bleeding in the lungs or meningitis). Weil's disease, the acute, severe form of leptospirosis, causes the infected individual to become jaundiced (skin and eyes become yellow), develop kidney failure, and bleed. Bleeding from the lungs associated with leptospirosis is known as severe pulmonary haemorrhage syndrome.
| Leptospirosis | |
|---|---|
| Other names | Rat fever, field fever, rat catcher's yellows, pretibial fever |
| Leptospira magnified 200-fold with a dark-field microscope | |
| Specialty | Infectious disease |
| Symptoms | None, headaches, muscle pains, fevers |
| Complications | Bleeding from the lungs, meningitis, kidney failure |
| Usual onset | One to two weeks |
| Causes | Leptospira typically spread by rodents |
| Risk factors | Exposure to infected animals, especially their urine, or fresh water or damp soil contaminated with infectious urine |
| Diagnostic method | Testing blood for antibodies against the bacterium or its DNA |
| Differential diagnosis | Malaria, enteric fever, rickettsiosis, dengue |
| Prevention | Personal protective equipment, hygiene measures, doxycycline |
| Treatment | Doxycycline, penicillin, ceftriaxone |
| Prognosis | Risk of death ~7.5% |
| Frequency | One million people per year |
| Deaths | 58,900 per year |
More than ten genetic types of Leptospira cause disease in humans. Both wild and domestic animals can spread the disease, most commonly rodents. The bacteria are spread to humans through animal urine or feces, or water or soil contaminated with animal urine and feces, coming into contact with the eyes, mouth, nose or breaks in the skin. In developing countries, the disease occurs most commonly in pest control, farmers and low-income people who live in areas with poor sanitation. In developed countries, it occurs during heavy downpours and is a risk to pest controllers, sewage workers and those involved in outdoor activities in warm and wet areas. Diagnosis is typically by testing for antibodies against the bacteria or finding bacterial DNA in the blood.
Efforts to prevent the disease include protective equipment to block contact when working with potentially infected animals, washing after contact, and reducing rodents in areas where people live and work. The antibiotic doxycycline is effective in preventing leptospirosis infection. Human vaccines are of limited usefulness; vaccines for other animals are more widely available. Treatment when infected is with antibiotics such as doxycycline, penicillin, or ceftriaxone. The overall risk of death is 5–10%. However, when the lungs are involved, the risk of death increases to the range of 50–70%.
It is estimated that one million severe cases of leptospirosis in humans occur every year, causing about 58,900 deaths. The disease is most common in tropical areas of the world but may occur anywhere. Outbreaks may arise after heavy rainfall. The disease was first described by physician Adolf Weil in 1886 in Germany. Infected animals may have no, mild or severe symptoms. These may vary by the type of animal. In some animals Leptospira live in the reproductive tract, leading to transmission during mating.