Findings and lessons from establishing Zika virus surveillance in southern Viet Nam, 2016

Objective@#To document the evolution and optimization of the Zika virus (ZIKV) disease surveillance system in southern Viet Nam in 2016 and to describe the characteristics of the identified ZIKV-positive cases.@*Methods@#We established a sentinel surveillance system to monitor ZIKV transmission in eight sites in eight provinces and expanded the system to 71 sites in 20 provinces in southern Viet Nam in 2016. Blood and urine samples from patients who met the case definition at the sentinel sites were tested for ZIKV using real-time reverse transcription polymerase chain reaction at the Pasteur Institute in Ho Chi Minh City (PI-HCMC). We conducted descriptive analysis and mapped the ZIKV-positive cases.@*Results@#In 2016, 2190 specimens from 20 provinces in southern Viet Nam were tested for ZIKV at PI-HCMC; 626 (28.6%), 484 (22.1%), 35 (1.6%) and 1045 (47.7%) tests were conducted in the first, second, third and fourth quarters of the year, respectively. Of these tested specimens, 214 (9.8%) were ZIKV positive with 212 (99.1%) identified in the fourth quarter. In the fourth quarter, the highest positivity rate was those in age groups 30–39 years (30.0%) and 40–59 years (31.6%). Of the 214 ZIKV-positive patients, 210 (98.1%) presented with rash, 194 (90.7%) with fever, 149 (69.6%) with muscle pain, 123 (57.5%) with joint pain and 66 (30.8%) with conjunctivitis.@*Discussion@#The surveillance system for ZIKV disease underwent several phases of optimization in 2016, guided by the most up-to-date local data. Here we demonstrate an adaptable surveillance system that detected ZIKV-positive cases in southern Viet Nam.

KAP investigation on dengue control at some communes in Nam Dinh province

KAP survey was conducted with 900 householders at three communes being endemic of dengue fever of Nam Dinh province before and after implementing dengue control measures. The results indicated community's knowledge on dengue was increased clearly, from 81.4% to 97.6% of households knew the transmission way of the disease. 83.4% of them know how to use mesocyclops for dengue vector control after carrying out the education and community mobilization. The collaborator network played a very important role in bringing information, improving knowledge, encouraging community participation to villagers, and supporting the active control measure and using mesocyclops for Aedes egypti larvae vector control

Epidemiological observation of dengue fever, dengue haemorrhagic fever in Nam Ha province, 1991-2000

DF/DHF is endemic disease in Nam Ha province with the following characteristics: low incidence, sporadicalness, persistence and unprediction. All four type of dengue virus was isolated and was the causative agents of DF/DHF epidemic in the province. Two species of mosquito vector were collected, and Aedes aegypti is major vector in transmitting dengue virus. Breeding sites of Aedes aegypti were investigated with up to seven different kind of water bodies and key breeding places of the vector for both urban and rural areas are concrete tanks, jars, wells and discarded objects. It is first time well is recognized as breeding site of Aedes aegypti and added into checking list for Aedes larvae in Northern part of Viet Nam

Community based method for dengue vector control in Nam Dinh province

The method of community participation was implemented at three communes of Nam Dinh province since 1998. Results from the fields show that vector indices were reduced significantly compared with that in the untreated commune. No dengue epidemic circulated at these communes. Using mesocyclops for dengue vector control was accepted easily by local people. Mesocyclops can recycle and develop once released in water containers. Its population can remain from 70% to 90% after introduced into resource containers

Some epidemiological characteristics of dengue fever and dengue hemorrhagic fever in Nam Hµ province during 1991 - 2000

Result of the research showed that dengue fever/dengue hemorrhagic fever (DF/DHF) was endemic disease in Nam Hµ province with following characteristics: low incidence (16.3/100,000 persons), sporadicalness, persistence and unpredictable. All four types of dengue virus were isolated and they were pathogens of DF/DHF endemic in this province. Two species of mosquito vector were collected, and Aedes aegypti was a major vector in transmitting dengue virus. Breeding sites of Aedes aegypti were investigated with up to seven different kinds of water body. It was determined that the key breeding places of the vector for both urban and rural area were concrete tanks, jars, wells and discarded objects. It was in first time documented the breeding site of Aedes aegypti and added into checklist for Aedes larvae in Northern part of Vietnam

Results after 2 years implementing methods to active the community role in dengue fever/dengue hemorrhagic fever control and prevention in Nam Ha province

Several methods for active the community role in dengue fever/dengue hemorrhagic fever control and prevention were implemented in 3 communes of Nam Hµ province from 1998 to 2000. These methods included health education to improve the knowledge of local people on this disease, eliminating discarded containers and introducing predacious Mesocyclops to large-size water containers. Results from the fields showed that the vector indices were reduced significantly compared with that in other untreated communes. No dengue epidemic circulated in the interventional communes. Using Mesocyclops for dengue control was accepted easily by local people. Mesocyclops can recycle and develop one released in water containers. Its population can remain from 70% to 90% after releasing