The look of leptospirosis in Victoria — recent trends

Of the 147 notified patients, 116 met the Communicable Diseases Network Australia 2004 case definition for leptospirosis.1 The cumulative incidence (for the period 2002–2012) was 0.2 per 100 000 population. Of the patients who met the case definition, 102 (88%) were classified as having locally acquired disease and 14 (12%) were classified as having overseas-acquired disease; 109 patients (94%) were male. The median patient age was 38 years (range, 10–79 years). Of those who acquired the disease locally, 99 (97%) acquired it in Victoria. Of the 14 patients who acquired the disease overseas, seven had travelled in Thailand. A majority of patients had animal-related or farming occupations (72/116; 62%). Using microagglutination testing, Leptospira interrogans serovar Hardjo was isolated from 74 patients (73%) and L. interrogans serovar Arborea from 12 patients (12%) among those with locally acquired disease. Among those with overseas-acquired disease, L. interrogans serovar Hardjo was isolated from four patients (29%), L. interrogans serovar Australis from three patients (21%) and L. interrogans serovar Copenhageni from three patients (21%).

The clinical presentations of the patients with leptospirosis are shown in the Box. Fever, headache and chills were present equally across both groups. The combination of fever and headache occurred frequently (100 patients; 86%), whereas a full constellation of symptoms (fever, headache, chills, myalgia or arthralgia, and conjunctival suffusion) occurred infrequently (11 patients; 9%). Antibiotic treatment was noted in 96 of 116 patients (83%): doxycycline in 69 (59%), penicillin or amoxycillin in 13 (11%) and ceftriaxone in six (5%). Sixty-six patients (57%) were hospitalised — 11 of those who acquired the disease overseas versus 55 of those who acquired it locally. Hospitalisation was associated with jaundice (P = 0.01) and renal impairment (P = 0.002) but unrelated to serovar (P = 0.18). One patient died.

Leptospirosis remains an infrequently notified disease in Victoria. It is usually acquired locally, primarily in men who work in agriculture and farming.1 Clinicians should be mindful of the non-specific nature of clinical presentation and should not rely on previously described uncommon classical signs (eg, conjunctival suffusion).2-4 Differences in clinical features between locally and overseas-acquired disease were not statistically significant, possibly due to the small number of patients with overseas-acquired disease. However, a trend was noted for renal impairment, which occurred more frequently in those with overseas- acquired disease (P = 0.07). Renal impairment and jaundice, known markers of severe disease,4 occurred in about one in five patients. Moreover, renal impairment occurred more frequently than previously reported in Australia.5