The Control of Typhoid Fever in Vietnam

Abstract

Abstract.Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), is a diminishing public health problem in Vietnam, and this process may represent a prototype for typhoid elimination in Asia. Here, we review typhoid epidemiology in Vietnam over 20 years and assess the potential drivers associated with typhoid reduction. In the 1990s, multidrug resistant S. Typhi were highly prevalent in a sentinel hospital in southern Vietnam. A national typhoid incidence rate of 14.7/100,000 population per year was estimated around the new millennium. The Vietnamese government recognized the public health issue of typhoid in the 1990s and initiated vaccine campaigns to protect the most vulnerable members of the population. At their peak, these campaigns immunized approximately 1,200,000 children in 35 provinces. Concurrently, Vietnam experienced unprecedented economic development from 1998 to 2014, with the gross national income per capita increasing from $360 to $1,890 over this period. More recent typhoid incidence data are not available, but surveillance suggests that the current disease burden is negligible. This trajectory can be considered a major public health success. However, a paucity of systematic data makes it difficult to disaggregate the roles of immunization and water, sanitation, and hygiene (WASH) interventions in typhoid reduction in Vietnam. Given the limitations of typhoid vaccines, we surmise the practical elimination of typhoid was largely driven by economic development and improvement in general population living standards. Better designed WASH intervention studies with clinical endpoints and systematic incidence data are essential to glean a greater understanding of contextual factors that impact typhoid incidence reduction.

Typhoid in Laos: An 18-Year Perspective

“…This province borders neighboring provinces in Vietnam and Thailand, where low typhoid incidence has also been reported. 3,4 In Vietnam, most patients present in the Mekong Delta area in the far south, and in Thailand, most cases are seen in the northwest. 3,4,24 The highest number of typhoid cases in Vientiane capital came from a rural district (Sangthong), which is the furthest district from the city center.…”

“…3,4 In Vietnam, most patients present in the Mekong Delta area in the far south, and in Thailand, most cases are seen in the northwest. 3,4,24 The highest number of typhoid cases in Vientiane capital came from a rural district (Sangthong), which is the furthest district from the city center. The high number of S. Typhi cases in rural populations has also been seen in other studies in the region, with the highest burden of typhoid fever in infants seen in rural communities in Cambodia.…”

“…Salmonella enterica serovar Typhi antibiotic resistance in Thailand also remains uncommon. 3,4 Of the 59 Lao MDR isolates, the majority of them (93.2%) were isolated between 2000 and 2004 with only four isolates cultured since 2004; the majority came from a single, probably clonal, outbreak in Oudomxay Province. The majority (96%) of ceftriaxone intermediate and resistant isolates were also obtained between 2000 and 2004.…”

“…Thailand reported a decrease in cases from 8.6 cases/100,000 people in 2003 to 3/100,000 people in 2014, 3 and Vietnam has reported a continued decline from an estimated incidence of 14.7/100,000 people in 2003. 4 Immunization programs were started in Thailand in the 1970s and Vietnam in the 1990s, which may have led to these decreases in case burden. 3,4 The role that water, sanitation, and hygiene initiatives and economic growth have also had in this decline is difficult to judge, although they have probably played a major role.…”

“…4 Immunization programs were started in Thailand in the 1970s and Vietnam in the 1990s, which may have led to these decreases in case burden. 3,4 The role that water, sanitation, and hygiene initiatives and economic growth have also had in this decline is difficult to judge, although they have probably played a major role. The WHO has long recommended immunization for people living in endemic areas and has recently advised the use of a new prequalified typhoid conjugate vaccine.…”