Trop Med Int Health. 2021 Oct 1. doi: 10.1111/tmi.13682. Online ahead of print.
ABSTRACT
OBJECTIVE: The clinical and serological characteristics of spotted fever group rickettsial (SFGR) infections in South Asia are poorly understood. We studied the clinical presentation and the IgM/IgG response in cases enrolled at two health care centres in South India.
METHOD: We enrolled 77 patients. 57 of these were recruited at a tertiary care centre, the remaining 20 at a community hospital (secondary care level). Diagnostic tests included IgM and IgG ELISA, and PCR. Over a period of one year, 41 cases were followed up for repeated sero-analysis.
RESULTS: Median age was 9 years (range 1 to 79). A rash was present in 74% of cases (57/77). In cases aged <15 years rash was present in 94% (44/47) vs 43% (13/30) in cases aged ≥15 years. An eschar was found in two cases (3%). Severe infection or complications occurred in 10 cases (13%). These included central nervous system infection (6/77, 8%), kidney injury (3/77, 4%), shock (3/77, 4%), lung involvement (2/77, 3%) and peripheral gangrene (2/77, 3%). IgM antibody levels increased faster after fever onset than IgG antibodies, peaking at 50 and 60 days respectively. After the peak, IgM and IgG levels showed a slow decline over one year with less than 50% of cases showing persistent IgG antibody levels.
CONCLUSION: SFGR infections in South India may be under-diagnosed, as many cases may not develop a rash. The proportion of cases developing severe infection seems lower than for scrub typhus in this region. IgG sero-prevalence may substantially under-estimate the proportion in a population with past SFGR infection.
PMID:34597443 | DOI:10.1111/tmi.13682
