Serological and blood culture investigations of Nepalese fever patients

Serological testing of paired (i.e. admission and convalescent) sera from 103 fever patients in Kathmandu, Nepal, was performed to estimate the prevalence rates of scrub typhus, murine typhus, Leptospira and dengue virus antibodies and to determine their role in the cause of active infections. Blood cultures from 15 patients grew Salmonella enterica serovar Typhi, 8 grew S. Paratyphi A and 6 grew other bacteria. Diagnostic antibody levels were detected against murine typhus (27/103; 26%), scrub typhus (23/103; 22%), Leptospira (10/103; 10%) and dengue virus (8/103; 8%). Nineteen patients (18%) had diagnostically raised antibodies to more than one infectious agent. Seven S. Typhi (7/15; 47%) and two S. Paratyphi A (2/8; 25%) patients had significant scrub typhus, murine typhus, Leptospira or dengue virus IgM antibody titres. This study confirms the presence of leptospiral, rickettsial and dengue infections in Kathmandu as well as evidence for mixed infections with S. Typhi and Orientia tsutsugamushi or Rickettsia typhi. These infections should be kept in mind when considering the differential diagnoses of fever and empirical treatment options in Nepal. Many patients demonstrated static IgM antibody results between paired serum collections, suggesting recent rather than acutely active infections.