Rickettsial Infections in Goa-Not Just Scrub Typhus!

BACKGROUND AND OBJECTIVE

Rickettsial infections are an important cause of undifferentiated febrile illness in tropics. While scrub typhus was reported from Goa, other rickettsial infections have not been reported earlier. The present study was planned to identify pattern of rickettsial infections in Goa.

MATERIALS AND METHODS

All patients presenting with undiagnosed acute febrile illness were recruited over a two-year period. Other causes of febrile illness were ruled out by appropriate tests. Sera of the patients were subjected to Weil Felix testing. Patients were labelled as probable rickettsial infection if the titres to any one antigen was >1:80 as per DHR-ICMR guidelines. Clinical details were obtained retrospectively from case records.

RESULTS

Sixty-one patients met inclusion criteria, of which six were excluded because of alternative diagnosis. Out of remaining patients, 32 were positive by Weil Felix test (positivity rate 58.18%). Eighteen were males; there was no age predilection. Twenty-one patients were positive for OXK (scrub typhus); of these, 13 were positive for other antigens also. Of the remaining, 6 were positive for OX2 alone, 2 were positive for OX 19 alone, one patient was positive for both OX2 and OX19 and 2 were positive for all three antigens. Most patients had non-specific clinical presentation. Two patients in scrub typhus group and one in spotted fever group died (mortality rate =9.5% and 11.1 %).

INTERPRETATION AND CONCLUSIONS

Our study shows that rickettsial infections other than scrub typhus are also prevalent in Goa. Weil Felix test is useful in diagnosis; however, there is cross reactivity between various antigens of the test, hence differentiation into various groups of rickettsiosis should not be done based on Weil Felix test alone.