The diagnosis of leptospirosis can be made in sick animals by using a checklist covering both clinical and laboratory features. Contact with an affected animal can identify humans with possible leptospirosis. This was developed by the World Health Organization (WHO).
Clinical Features
Clinical Feature |
Finding |
Points |
fever |
yes |
2 |
|
no |
0 |
malaise, weakness, listlessness, depression |
yes |
1 |
|
no |
0 |
convulsions |
yes |
1 |
|
no |
0 |
conjunctivitis |
yes |
2 |
|
no |
0 |
anemia |
yes |
2 |
|
no |
0 |
hemorrhages |
yes |
5 |
|
no |
0 |
hemoglobinuria |
yes |
10 |
|
no |
0 |
jaundice |
yes |
5 |
|
no |
0 |
abortion/stillbirth or jaundiced/hemorrhagic newborn |
yes |
20 |
|
no |
0 |
mastitis with discolored milk (in cattle) |
yes |
10 |
|
no |
0 |
Laboratory Features
Culture:
• isolation of leptospira on culture allows for definitive diagnosis.
Serologic Testing |
Vaccination Status |
Finding |
Points |
single high titer |
unvaccinated |
yes |
10 |
|
|
no |
0 |
|
vaccinated |
yes |
5 |
|
|
no |
0 |
rising titers with paired samples |
unvaccinated |
yes |
30 |
|
|
no |
0 |
|
vaccinated |
yes |
20 |
|
|
no |
0 |
likelihood score =
= SUM(points for clinical features) + SUM(points for laboratory features)
Interpretation:
• minimum likelihood score: 0
• maximum likelihood score: 88
• Isolation of leptospira on culture allows definitive diagnosis.
• With negative cultures the higher the likelihood score the greater the probability of leptospirosis.
Likelihood Score |
Diagnosis of Leptospirosis |
<= 20 |
unlikely |
21 – 29 |
possible |
>= 30 |
presumptive |
Specialty: Infectious Diseases