The evidence for rickettsial disease arising in New Zealand

To describe the first cases of serologically proven riskettsial disease reported in non-travelling New Zealanders.

We used clinical and laboratory based surveillance, review of clinical records and patient interviews. Information collected included demographics, presenting signs and symptoms, laboratory results, treatment and outcome. A limited seroprevalence study of rural-living friends and relatives was performed. We tested for rickettsial antibodies in the sera of possums trapped on properties close to the area of residence of the first two cases.

Serological results support the diagnosis of a rickettsial disease in nine patients. Clinical findings at presentation were nonspecific but included fever, rigors and headache. A rash was noted in four (44%). All had abnormal liver enzymes. Eight were hospitalised. No patient died but two were admitted to intensive care.

There is strong clinical and serological evidence that Rickettsia typhi (the causative organism of murine typhus) or a Rickettsia typhi-like organism is present in the greater Auckland region. To prove it, the organism will need to be cultured or rickettsial DNA detected by molecular methods. Rickettsial infection needs to be included in the differential diagnosis of patients presenting with fever, headache and myalgia, particularly in those with rural lifestyles at least in the greater Auckland area.