Case number 2:

A previously healthy 24-year-old male presents to a Houston emergency center with a 5-day history of headaches, fever, chills, nausea, vomiting, right upper quadrant abdominal pain, and myalgias. His home in downtown Houston flooded last week and he was recently evacuated to a safe location.   Physical exam revealed conjuctival suffusion .

Which of the following is the most likely etiological agent causing the above symptoms:

1. Protozoa
2. Spirochete
3. Mycobacterium
4. Virus

Answer: Spirochete

This was a case of Leptospirosis (Weil’s disease). Leptospirosis is a waterborne zoonosis caused by the spirochete Leptospira interrogans. It is the most common zoonotic disease worldwide. Rodents are the most important reservoirs, and infection typically arises after broken skin is exposed to freshwater or soil contaminated with urine from infected animals.

Most cases of leptospirosis are mild and self-limiting , however 5 – 10 % of patients can present with a severe form of the disease known as Weil’s disease. This condition is associated with renal failure, jaundice and bleeding diathesis. Conjuctival suffusion (as seen above) in the setting of scleral icterus is a pathognomonic sign of leptospirosis, making the other diagnoses less likely. Other complications that can occur with severe leptospirosis include pulmonary heamorrhages, aseptic meningitis, acalculus cholecystitis, rhabdomyolysis, fulminant liver failure, myocarditis and acute tubular necrosis (ATN).

Routine laboratory tests commonly reveal thrombocytopenia, transaminitis, raised bilirubin,  hyponatremia, and elevated creatine phosphokinase levels. Pyuria, proteinuria, and microscopic hematuria can also been seen on urinalysis. Diagnosis is mostly through serology by microscopic agglutination testing, or by PCR. For mild cases, outpatient treatment with oral doxycycline for 5- 7 days is reasonable. For more severe cases however,  parental therapy treatment with IV penicillin or a third generation cephalosporin such as ceftriaxone or ceftazidime is preferred, along with inpatient monitoring and supportive care.

There was a good case of leptospirosis in the NEJM Clinical Problem Solving section