​Infectious Diseases and Microbiology - Biphasic Illness ( Leptospira interrogans)

​Infectious Diseases and Microbiology - Biphasic Illness ( Leptospira interrogans) 
A biphasic Illness 
Leptospira interrogans is a type of bacteria that belongs to the group of Gram-negative spirochetes. Transmission occurs via contact with water and soil that have been polluted with urine from infected animal reservoirs, including dogs, cattle, rats, and other wild animals. There are two distinct syndromes that can be clinically identified: anicteric and icteric.


Leptospirosis is caused by L interrogans. The majority of individuals who are infected will exhibit the anicteric type, characterized by flu-like symptoms such as fever, chills, and myalgia. The biphasic clinical course is a well-known phenomenon where a second immune-mediated phase may occur. Certain individuals may exhibit the more severe icteric variant, also known as Weil syndrome, which is characterized by significant vascular injury that frequently leads to liver and kidney failure.

Spirochetes enter the bloodstream and multiply after penetrating through damaged skin and mucous membranes. They then spread to other tissues. The initial infections are eliminated by the humoral immune response, but the formation of immunological complexes leads to the subsequent phase of the disease.
Laboratory serology is employed for diagnostic purposes. Microorganisms can occasionally be cultivated from blood or cerebrospinal fluid, although this is only possible during a limited period of infection.

The course of treatment is determined by the extent of symptoms, and typically involves the administration of antibiotics such as penicillin and tetracyclines. Prevention entails administering prophylactic doxycycline to persons at high risk and vaccinating household animals.