Dengue fever prevention and control/yellow fever

In many ways the 2002 resolution on dengue fever prevention and control and the way towards it can be considered as exemplary for all WHO work in relation to vector- borne diseases, and maybe even for all programmes related to water and health. This comparison can be made on the basis of two aspects: approaches and goals.

In the early days, WHO had many technical officers that went into the field and executed and managed programmes and budgets for the country concerned. Although attention was given to several aspects of reasons and consequences of dengue fever the focus was mainly on one aspect which in the case of vector-borne diseases was the eradication of the vector through the use of pesticides. The practice of employing WHO staff directly into the member states is not considered appropriate anymore no that all member states are fully independent and sovereign. Therefore the role of WHO, its HQ, regional and country offices is much more that of an adviser. The implementation of programmes and budgets is left to governments itself. The WHO is there to provide guidance through its expertise. Also, the ideas of how to deal with vector-borne diseases has changed markedly. It is acknowledged that there are many aspects to controlling a disease and its consequences. This acknowledgement goes in parallel with the modification of the goals of programmes that address vector-borne diseases. In the past dengue programmes, like malaria programmes had the goal of the eradication of the disease. This goal has, in all cases, proved to be unattainable. There are many different reasons for this. The eradication of vectors by pesticides proved impossible: there is no way to reach each and every mosquito and vectors become resistant to the pesticides used. Urbanisation, increasing populations and changing life styles also contribute to the proliferation of the mosquito vector. To paint an even bleaker picture, the near eradication of vectors leads to an increased chance of an outbreak as people lose resistance to the disease. This is exacerbated by a slump in popular and governmental willingness to continue to take the necessary precautions. There does not exist a simple solution to any health problem. Even where there is proper medication like in the case of yellow fever, this is not sufficient to eradicate the disease. Even when there is ample supply of cheap medication there is no possibility to provide every one with it and a decrease of a disease leads to a higher susceptibility. That is why the programmes to eradicate vector-borne diseases, like dengue and malaria, are now directed towards the prevention and control of the disease and its consequences.

The present strategy to prevent and control dengue fever and dengue haemorrhagic fever was a result of and response to the dengue situation in the Americas in the 1970s. In the course of the 1970s the A. aegypti mosquito, the dengue vector, was almost eradicated in the Americas. Through a lack of continued effort to keep this vector at bay it was allowed to linger and eventually come back with a vengeance. In the 1990s, realizing the ever increasing occurrence of dengue PAHO, the WHO regional office for the Americas, put new life into a dengue fever control and prevention. Realizing dengue is a global phenomenon this revived attention turned into a global strategy on dengue fever/dengue haemorrhagic fever prevention and control. A global strategy that does not prevent region or country specific approaches. This new strategy recognizes the necessity of a comprehensive approach that addresses all aspects of the disease. The three main areas are:

o Vector control: through pesticides and water resource management o Clinical management: the reduction of the disease burden, particularly the reducing case fatality rates, through the provision of vaccines e.g. o Behaviour change: a social element was added as human behaviour is often a part of the problem, because without community participation programmes have no chance to succeed and because technical aspects do not change behaviour

The role of WHO in this is to provide scientific evidence and guidelines on each of these aspects, provide technical training and initiate pilot schemes. Water management has its place in this strategy as a means of vector control and behavioral change. It is important that none of the different aspects becomes overshadowed by another as none of the aspects by itself is a sufficient answer to the problem. The results of such a strategy largely depends on the commitment of governments and on community participation, but the WHO and the international community do have ways to bring the problem other the attention of these main parties. Major conferences are held on the topic of dengue fever and other vector-borne diseases to keep the focus on these important health problems. Also, key problems can be advocated when the expenditure of WHO budgets are negotiated with member states. But unfortunately, the main stimulus is usually the outbreak of an epidemic. This leads to much attention to the problem and many funds being directed to stop it. Attention and funds that may not have been necessary had proper precautions been in place. Another reason why dengue is in many ways like other water related health programmes.