Seroprevalence of Scrub Typhus, Typhus, and Spotted Fever Among Rural and Urban Populations of Northern Vietnam

Abstract

Rickettsial infections are recognized as important causes of fever throughout southeast Asia. Herein, we determined the seroprevalence to rickettsioses within rural and urban populations of northern Vietnam. Prevalence of individuals with evidence of prior rickettsial infections (IgG positive) was surprisingly low, with 9.14% (83/908) testing positive to the three major rickettsial serogroups thought to circulate in the region. Prevalence of typhus group rickettsiae (TG)–specific antibodies (6.5%, 58/908) was significantly greater than scrub typhus group orientiae (STG)– or spotted fever group rickettsiae (SFG)–specific antibodies (P < 0.05). The majority of TG seropositives were observed among urban rather than rural residents (P < 0.05). In contrast, overall antibody prevalence to STG and SFG were both very low (1.1%, 10/908 for STG; 1.7%, 15/908 for SFG), with no significant differences between rural and urban residents. These results provide data on baseline population characteristics that may help inform development of Rickettsia serological testing criteria in future clinical studies.

A review of the global epidemiology of scrub typhus

“…The reported seroprevalence of O . tsutsugamushi for each country is shown in Table 1 [ 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 , 104 , 105 , 106 ]. The reports of outbreaks of scrub typhus are summarized in Table 2 [ 43 , 94 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , …”

“…There was only one study in the central part of Vietnam, Quang Nam province, which identified that the main genotype in the area was the Karp group [ 180 ]. Recent studies of scrub typhus in North Vietnam demonstrated that the cumulative incidence of scrub typhus was about 1.1% among the general population, and ~3.5% among patients admitted to hospitals [ 103 , 105 ]. The peak season in North Vietnam is summer though cases occur throughout the year.…”

“…The transmission pattern of scrub typhus in tropical South Vietnam may be different because a seasonal pattern is more obvious in a temperate climate [ 66 , 105 ]. There was no significant difference between urban and rural areas [ 103 ].…”

Scrub Typhus: Historic Perspective and Current Status of the Worldwide Presence of Orientia Species

“…In 1915, a fever of unknown etiology among two individuals was reported in Saigon, Vietnam [ 50 ] to be a disease similar to that described in Deli, Sumatra (i.e., pseudotyphoid), that was later determined to be scrub typhus [ 24 ]. Subsequently, the presence of scrub typhus throughout Vietnam was confirmed [ 38 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ].…”

<p>Clinical Features, Laboratory Characteristics and Prognostic Factors of Severity in Patients with Rickettsiaceae at Two Military Hospitals, Northern Vietnam</p>

“…In Vietnam, the serum antibody prevalence of Orientia tsutsugamushi causing scrub typhus, Rickettsiatyphi causing murine typhus and other Rickettsia of spotted fever group in the community of northern Vietnam were 1.7%; 6.5% and 1.1%, respectively. 7 There have been reports of R. felis causing human illness in central Vietnam. 8 In the National Hospital for Tropical Diseases, Rickettsioses account for one-third of acute undifferentiated fevers with the mortality rate of 5.4% between 2015 and 2017.…”