Leptospirosis - Causes, Risk Factors, Pathology, Signs & Symptoms, Diagnosis, And Treatment
Video transcript :-
Leptospirosis is an infectious disease of humans and animals caused by the spirochetes of the genus Leptospira.
It is considered the most common zoonotic disease in the world and is more prevalent in tropical regions.
The disease is commonly associated with poor sanitation and agricultural occupations where there is contact of animals with water.
In animals, bacteria spread hematogenously, and colonize the proximal renal tubules.
These animals shed bacteria chronically when they pass urine.
Humans are the accidental host, and the disease is transmitted via the exposure of mucus membranes or damaged skin to an acutely infected animal or fresh water contaminated with the urine of a chronic carrier, particularly a rodent.
Additionally, the organisms can also enter the body through inhalation of aerosolized body fluids.
People who are at risk include the following.
Farm workers and field agricultural workers.
Veterinarians.
Pet shop owners.
Plumbers.
Meat handlers and slaughterhouse workers.
Workers in the fishing industry.
Sewer workers.
Military troops.
And travelers, especially hikers and mud runners.
Upon entry to the body, the organisms gain rapid access to the blood stream through lymphatics and spread to the organs in the body.
The incubation period is usually 5 to 14 days.
Pathologic effects are seen in almost every organ in the body.
Most of these effects are immune mediated and not due to infection itself.
Vasculitis in capillaries is the most consistent finding in leptospirosis.
Endothelial edema, necrosis, and lymphatic infiltration can lead to loss of red blood cells and fluids, resulting in hypovolemia.
In the kidneys, interstitial nephritis, tubular necrosis, and capillary vasculitis can lead to renal failure.
In the liver, there is centrilobular necrosis and Kupffer cell proliferation, which can cause jaundice.
In the lungs, pulmonary hemorrhages are seen, which is the major cause for leptospirosis associated death.
In the heart, interstitial myocarditis is seen.
Adrenal hemorrhages can also occur.
Other effects include disseminated intravascular coagulation, hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, and thrombocytopenia.
2 distinct phases of leptospirosis infection have been identified.
Septicemic or acute phase, immune or delayed phase.
During the acute phase, the patient will have headache, fever with chills and rigors, muscle pain, nausea and vomiting, diarrhea, a dry cough and pharyngitis, and conjunctival suffusion.
Acute phase usually lasts for about 5 to 7 days.
Initial febrile period is followed by 1 to 3 days of fever free period.
Recurrence of fever marks the beginning of the immunologic phase.
During this phase, patients will have severe headache, which does not respond to simple analgesics.
They will also have muscle pain, abdominal pain, diarrhea, hepatosplenomegaly, nausea and vomiting, and anorexia.
The most important clinical syndrome in this phase is aseptic meningitis, where the patient has various nerve palsies, altered consciousness, and meningism.
Acalculous cholecystitis is a rare, but clinically significant finding in this phase.
Eye manifestations such as uveitis and chorioretinitis can also occur.
Renal manifestations include hematuria and oliguria.
The more severe form, known as Weil syndrome, or icteric leptospirosis, carries a high mortality rate and is associated with widespread organ dysfunction.
Features of Weil syndrome include profound jaundice with hepatic necrosis, pulmonary hemorrhages, which can lead to respiratory failure, and renal dysfunction.
Diagnosis of leptospirosis is by the microscopic agglutination test, which detects antibodies against Leptospira.
Additional test should be performed to assess the organ involvement and severity.
These include complete blood count, coagulation profile, serum creatinine, serum bilirubin, alkaline phosphatase levels, urinalysis, CSF analysis to exclude other causes of meningitis, and ECG, especially in suspected Weil syndrome.
In severe cases, chest radiography and CT, as well as ultrasound to assess the biliary system, may also be required.
Treatment of mild leptospirosis is with doxycycline.
For severe disease, intravenous penicillin and ceftriaxone should be given.
In addition, patients should be managed in a monitored setting where facilities for mechanical ventilation and airway protection are available.
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