Dengue treatment at a hospital in Phu Yen province.

In recent years, the situation of dengue fever in Viet Nam has still remained complicated, outreaching the control of localities and posing possible risks of large-scale epidemics, especially in Phu Yen province (with reported 1,495 dengue cases and 3 fatal cases for the first half of 2013).

Phu Yen province is composed of 9 districts, towns and cities. The evaluation of the dengue fever situation, vector index surveillance and control activities in the districts where fatal cases show that:

- For the first half of 2013, there were reportedly 1,166 dengue cases, more than 3,89 times in comparison with the same period (299 cases), with 2 fatal cases. The morbidity have significantly increasedsince May in 9 districts, towns and cities; with the highest cases reported in Dong Hoa (229 cases, 19.63%), Phu Hoa (177 cases, 15.18%), Song Hinh (168 cases, 14.40%), and Tay Hoa (152 cases, 13.03%).

- Until 14/7/2013, the morbidity of the whole province were 1,495, including 3 deaths. The fatality (morbidity/mortality) rate were reported mainly in Dong Hoa (297/2), Tuy Hoa (149/1), Phu Hoa (214/0), Tay Hoa (183/0), Tuy An (97/0), Song Cau (94/0), Dong Xuan (38/0), Son Hoa (218/0), and Song Hinh (223/0); and 67 foci of various scales were detected. To deal with the worsening dengue situation, the provincial health sector coordinated closely with local systems to timely treat 100% of the detected foci.

Chart of the dengue patients fluctuation in the first half of 2013 in Phu Yen

Dengue fever vectors

At the beginning of the year, the Phu Yen health sector conducted monitoring and evaluation campaigns over the dengue vector and larval control activities at the "hot-spot" communes/wards, and held various sanitary activities to eliminate larval breeding sites. However, these activities are mostly deployed in the form of campaigns and "follow the crowd", which resulted in lack of quality activities. Although the investigations of entomological indexes are conducted before and after the dengue outbreak treatment, the larval control activities are not maintained, which could be considered the cause of the long-lasting epidemics. In July 2013, the entomologists of the IMPE-QN had collaborate with the provincial health units to implement the vector supervisions in 3 sites with deaths from dengue, including Xuan Hoa village (Hoa Kien Kien commune, Tuy Hoa City); Phu Hiep 2 (Hoa Hiep Trung -Dong Hoa); Phu Luong (Hoa Tan Dong-Dong Hoa). The results found that:

Ae. Aegypti indexes in some areas of Phu Yen province

^*Note: DI: Density index (mosquito/house); AHI: Adult House Index (%); BI: Breteau index; HI: House Index (%); CI:Container Index (%)

During the dengue vector investigations, the weather fluctuations with intermittent rainy and sunny days, and temperatures and humidity are favourable for the reproduction and development of the dengue vector. o­nly An.agypti mosquitoes were collected at the surveyed sites, at a very low density (0 - 0.1 mosquito/house), indicating the effectiveness of the insecticide spraying campaigns o­n adult mosquitos. However, the BI in Hoa Kien commune (Tuy Hoa city) and Hoa Hiep Trung commune (Dong Hoa district) are close to the threshold of high risk, especially in Phu Luong village, Hoa Tan Dong commune (Dong Hoa district) with the BI of 50 and the HI up to 40%. Although various environmental sanitization campaigns and insecticidal sprayings were conducted in these localities (twice per year), the larvae index is still high, proving that the larvae eliminating activities in most localities are just formalistic, thus predicting the persistent and re-emerging dengue epidemics. The results of the larvae source surveillance showed a great variety of containers (vases, jars, buckets/barrels, discards, cement tanks, etc) but vases occupy the highest proportion, accounting for 53.33% in comparison with the whole detected larvae containers, then jars (20%), and cement tanks (13.33)

Insecticide spraying to control vector and community activities

The larval elimination and insecticidal spraying campaigns in the localities had resulted in particular effects, reducing the adult mosquito population. Although the foci were treated actively and o­n a larger communal/district scale, the environmental sanitation did not meet the targets as previously required. The other departments and sectors didn't take their active part in those activities, most just call upon the people to get involved in larval control activities instead of performing their roles in practice. Health education messages o­n dengue control wasn't informed to the households, some people still didn't own proper knowledge that larval eliminating activities would bring the best effects to the community rather than longing eagerly for the insecticide spraying.

The causes of the worsening dengue situation and predictions in the second half of 2013

At present, the dengue situation in Phu Yen still remains complicated, as it is predicted that in the last 6 months of 2013, the epidemics in some localities are likely to outbreak due to the unfavorable weather conditions which are advantageous to the reproduction and development of the transmitting mosquitoes; simultaneously make the people impatient in cleaning the water container inside and around the house. The larval eliminating activities in the localities are not deployed thoroughly and regularly. Local people and health workers have the subjective point of view after the achieving the decreased morbidity. The district medical centers don't counsel the local People's Committees specifically to direct straight and mobilize the other departments, sectors and the people to take part in the larval eliminating activities. In some district of Phu Yen such as Tuy Hoa city and Dong Hoa district, the people has the custom of putting flower pots in the houses but they don't allow health workers to check for larvae, causing a lot of difficulties to environmental sanitation. In addition, larval elimination activities are not conducted o­n time, which help to prolong the epidemics and then spread to other areas o­n a larger scale. The main reason of the prolonged epidemics derives from the larval eliminating activities which are not effective and not maintained regularly. Furthermore, local people are not encouraged to improve their awareness o­n eliminating the larval sources in their houses, so in some areas the vector indexes are still high even after the implementation of larval elimination activities.

Some recommended solutions

The Preventive Medical Center of Phu Yen Province and other affiliated bodies at grassroots level need to act as counselor for the authorities to propagandize, educate to improve the people's awareness of larval elimination, paying special attention o­n throwing discards, turning upside down the unnecessary containers and regularly changing the water of the flower pots in the house. Before applying insecticidal campaigns, the health workers need to deploy the environmental sanitation actively to eliminate larvae thoroughly, for insecticide spraying can eliminate o­nly the adult mosquitoes but the larvae; consequently the remaining larvae in these households will grow up into adult mosquitoes, which makes the people misunderstand that the spraying is a technical fault. More important, The standardized-ULV sprayers should be used with proper techniques, dosage and usage methods. Directions should be sent to local medical stations to supervise and speed up the activities of the health volunteer network; to attend monthly vector surveillance together with the supervision of the volunteers' activities. Moreover, the district health level should be directed to follow, monitor the morbidity cases regularly, and supervise the vectors to give precise directions timely, at the same times to give wise counsel for epidemic treating decisions, for it is the fact that any area with reported dengue incidence and high dengue indexes must be the place that epidemics can easily occur. Another recommendation is related to the deployment of outdoor insecticidal spraying in the places where Ae. albopictusis found, together with regular inspection and monitoring of the health volunteers, and active activities in case of increased vector index occurrence.

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