Metagenomic Approach to Characterizing Disease Epidemiology in a Disease-Endemic Environment in Northern Thailand

Takhampunya, Ratree; Korkusol, Achareeya; Pongpichit, Chalermpol; Yodin, Komsan; Rungrojn, Artharee; Chanarat, Nitima; Promsathaporn, Sommai; Monkanna, Taweesak; Thaloengsok, Sasikanya; Tippayachai, Bousaraporn; Kumfao, Naruemon; Richards, Allen L.; Davidson, Silas A.

The seroprevalence of the most prevalent pathogenic bacteria was determined in UFI patient sera (n = 200). IFA and ELISA assays were performed to examine the presence of IgM or IgG antibodies and to measure the titer of IgG antibody in UFI patients ( Table 5 ). The results of IFA assays testing for IgM antibodies against scrub typhus, murine typhus and spotted fever group Rickettsia (SFGR) showed relatively high numbers of patients with past infection. Patients with IgM antibody against murine typhus had the highest number accounting for 33.0% (66/200), followed by SFGR (28.0%, 56/200), and scrub typhus (20.0%, 40/200). However, when the same set of sera (n = 200) were tested for their IgG titer, scrub typhus seems to dominate the other two diseases with 154 patients having higher titers (1,600 and >6,400), compared to SFGR (n = 26) or murine typhus (n = 0) ( Table 5 and Figure 6A ). Cross-reactivity between scrub typhus and rickettsiosis was determined using positive controls from commercial kits and the results showed no cross-reactivity was found among these pathogens for IgG and IgM. Patients were grouped into four age groups; <19, 20-40, 41-60, and >60 years old, and by sex; male and female, to determine how seroprevalence to rickettsiosis and scrub typhus differed among the groups. The data showed higher seroprevalence (both IgM and IgG) of the two diseases in two age groups (20-40 and 41-60 years old) compared to the other two age groups (<19 and >60) with statistical significance (Figures 6B,C) . However, the overall prevalence was not different between male and female patients. In addition, lower seroprevalence (IgG) was observed for other pathogens such as B. quintana (9.5%, 19/200), B. henselae (8.0%, 16/200), and A. phagocytophilum (0.5%, 1/200) ( Table 5) .