Each module in this topic series covers a distinct pathway. However, in clinical practice, these exposures co-occur in the same patients. Planetary health reasoning means seeing the whole picture rather than addressing each symptom in isolation.
Mapping the exposures
A sentence to tell students what they need to do now or consider. Why is it important to map the exposures?
Contamination of freshwater streams with animal reservoir urine (rodents, cattle, pigs) → direct mucocutaneous exposure during swimming → leptospiral infection.
Significant physiological heat strain and dehydration → compounding constitutional symptoms (fatigue, myalgia) that overlap with and initially masked the leptospiral prodrome.
Significant physiological heat strain and dehydration → compounding constitutional symptoms (fatigue, myalgia) that overlap with and initially masked the leptospiral prodrome.
What integration does
The first ED physician had a satisfying explanation:
- A strenuous race in extreme heat. Elevated CK.
- Bilateral calf tenderness.
- A presumed viral illness with conjunctival involvement.
Â
Each finding mapped cleanly onto rhabdomyolysis or viral syndrome. The environmental history was not taken because the existing explanation seemed sufficient.
What the environmental history now reveals is that the same documented findings carry a different meaning. Calf tenderness and elevated CK in a patient who ran a race in extreme heat are expected. Calf tenderness and elevated CK in a patient who swam in a flooded Hawaiian river valley the following day are recognized features of leptospirosis.
The conjunctival redness, reasonably attributed to a viral syndrome on the first visit, is recognizable as conjunctival suffusion—a characteristic leptospiral finding—once the exposure history is known. The findings did not change between visits. Their meaning changed because the history changed.
The integrated picture changes three things
1
The differential now leads with leptospirosis alongside rhabdomyolysis as a co-diagnosis rather than the primary explanation.
2
The investigation adds leptospira-specific testing to the existing CK, LFTs, renal function, and urinalysis. The choice of test depends on timing: PCR on blood or urine has the highest yield in the first week, while serology (IgM ELISA, MAT) becomes more reliable in the second week, when this patient presents.
3
The treatment decision depends on recognizing the environmental exposure history. Guidelines advise starting empiric antibiotics on clinical suspicion rather than waiting for serology, with the medication choice guided by severity. Oral doxycycline is appropriate for mild, early disease, while intravenous penicillin or ceftriaxone is preferred for severe or progressing disease, as suspected here.
A landmark 2023 NEJM review article providing the most comprehensive and current evidence base for the water section of this module. Recommended for students who want to go deeper.
Semenza JC, Ko AI. Waterborne diseases that are sensitive to climate variability and climate change. N Engl J Med. 2023;389(23):2175–2187.Â
Image credits
Unless otherwise noted, images are from Adobe Stock.