Leptospirosis

Leptospirosis is an infection caused by corkscrew-shaped bacteria called Leptospira. Signs and symptoms can range from none to mild such as headaches, muscle pains, and fevers to severe with bleeding from the lungs or meningitis. If the infection causes the person to turn yellow, have kidney failure and bleeding, it is then known as Weil's disease. If it also causes bleeding into the lungs then it is known as severe pulmonary haemorrhage syndrome. Leptospirosis is an infection caused by corkscrew-shaped bacteria called Leptospira. Signs and symptoms can range from none to mild such as headaches, muscle pains, and fevers to severe with bleeding from the lungs or meningitis. If the infection causes the person to turn yellow, have kidney failure and bleeding, it is then known as Weil's disease. If it also causes bleeding into the lungs then it is known as severe pulmonary haemorrhage syndrome. Up to 10 different genetic types of Leptospira may cause disease in humans. It is transmitted by both wild and domestic animals. The most common animals that spread the disease are rodents. It is often transmitted by animal urine or by water or soil containing animal urine coming into contact with breaks in the skin, eyes, mouth, or nose. In the developing world the disease most commonly occurs in farmers and low-income people who live in cities. In the developed world it most commonly occurs in those involved in outdoor activities in warm and wet areas of the world. Diagnosis is typically by looking for antibodies against the bacterium or finding its DNA in the blood. Efforts to prevent the disease include protective equipment to prevent contact when working with potentially infected animals, washing after this contact, and reducing rodents in areas where people live and work. The antibiotic doxycycline, when used in an effort to prevent infection among travelers, is of unclear benefit. Vaccines for animals exist for certain type of Leptospira which may decrease the risk of spread to humans. Treatment if infected is with antibiotics such as: doxycycline, penicillin, or ceftriaxone. Weil's disease and severe pulmonary haemorrhage syndrome result in death rates greater than 10% and 50%, respectively, even with treatment. It is estimated that seven to ten million people are infected by leptospirosis per year. This results in about 58,900 deaths per year. The disease is most common in tropical areas of the world but may occur anywhere. Outbreaks may occur in slums of the developing world. The disease was first described by physician Adolf Weil in 1886 in Germany. Animals which are infected may have no symptoms, mild symptoms, or severe symptoms. Symptoms may vary by the type of animal. In some animals Leptospira live in the reproductive tract, leading to transmission during mating. The symptoms appear after an incubation period of 7–12 days. However, the incubation period can vary from 6 days to 29 days. Leptospirosis is a biphasic disease. The first phase (acute or septic phase) ends after 3–7 days of illness. The second phase (immune phase) starts with the resolution of symptoms and appearance of antibodies. Ninety percent of cases of the disease are mild leptospirosis. The rest experience severe disease, which develops during the second stage or occurs as a single progressive illness. Leptospiral infection in humans causes a range of symptoms, and some infected persons may have no symptoms at all. The disease begins suddenly with fever accompanied by chills, intense headache, severe muscle aches, abdominal pain, and occasionally a skin rash. These symptoms are non-specific to leptospirosis and can occur in other infectious diseases. The headache in leptospirosis is characteristically located at the bilateral temporal regions, or frontal headache with throbbing pain, associated with pain behind the eyes and sensitivity to light. Muscle pain usually involves the calf muscle and the lower back. The most characteristic feature of leptospirosis is the conjunctival suffusion (conjunctivitis without exudate) which is not commonly found in other febrile illnesses. Other characteristic findings on the eye include subconjunctival bleeding and jaundice. Rash is rarely found in leptospirosis. When rash is found, other alternative diagnoses such as Dengue fever and Chikungunya fever should be considered. However, rashes can be found in front of the shinbone in the case of “Fort Bragg Fever” which was recorded among soldiers at Fort Bragg, North Carolina in 1942. Dry cough is observed in 20% to 57% of people with leptospirosis. Thus, this clinical feature can mislead a doctor to diagnose the disease as respiratory illness. Besides, gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea frequently occurs. Vomiting and diarrhea may contribute to dehydration in conjunction with high-output kidney failure due to excessive urine output. The abdominal pain can be due to acalculous cholecystitis or inflammation of the pancreas. Rarely, the lymph nodes, liver, and spleen may be enlarged and palpable. The disappearance of symptoms coincides with the appearance of antibodies against Leptospira and the disappearance of all the bacteria from the bloodstream. The patient is asymptomatic for 3–4 days until the second phase begins with another episode of fever. The immune phase can last from 4 to 30 days. It can be anything from meningitis, kidney failure, lung symptoms with or without bleeding, eye pain, and muscle pain The hallmark of the second phase is meningitis (inflammation of the membranes covering the brain). Signs and symptoms of meningitis include severe headache and neck stiffness. In 5% to 10% of those infected with jaundice, the disease can be rapidly progressive to multiorgan failure. Severe leptospirosis can cause liver, kidney, lungs, and brain damage. For those with signs of meningoencephalitis, altered level of consciousness can occur. A variety of neurological complications can occur such as hemiplegia, transverse myelitis, and Guillain-Barré syndrome. Signs of bleeding such as petechiae (non-traumatic bruises at 1 mm), ecchymoses (non-traumatic bruises more than 1 cm), epistaxis (nose bleeding), melena (blood in stools), haematemesis (vomiting blood) and pulmonary haemorrhage (bleeding from the lungs) can also be found. Prolongation of prothrombin time (PT) in coagulation testing is associated with severe bleeding manifestation. However, low platelet count (thrombocytopenia) is not associated with severe bleeding. In less than 5% of those infected, pulmonary haemorrhage can occur at the 4th to 6th day of the illness and can be rapidly fatal. Leptospira causes alveolar haemorrhage (bleeding into the alveoli of the lungs) and massive haemoptysis (coughing up blood). This causes acute respiratory distress syndrome (ARDS). This feature increases the risk of death to more than 50%. Rarely, myocarditis, pericarditis, heart block and abnormal heart rhythms may occur. The classic form of severe leptospirosis is known as Weil's disease, which is characterized by liver damage (causing jaundice), kidney failure, and bleeding. Leptospirosis is caused by aerobic, right handed helical bacteria belonging to the genus Leptospira; sized at 6 to 20 micrometers. Hooked ends of this bacterium give it a 'question mark' shape. Like Gram-negative bacteria, Leptospira have an outer membrane studded with lipopolysaccharide (LPS) on the surface, an inner membrane, and a layer of peptidoglycan. However, unlike Gram-negative bacteria, the peptidoglycan layer in Leptospira lies closer to the inner membrane than the outer membrane. This results in a fluid outer membrane loosely associated with the cell wall. In addition, Leptospira have two flagella located in the periplasm. Chemoreceptors are located at the poles of the bacteria that sense various substrates and change the direction of the bacteria's movement. The bacteria are traditionally visualised using dark-field microscopy using silver staining or immunofluorescence staining.