Academic journal article Bulletin of the World Health Organization

Knowledge of Mosquitos in Relation to Public and Domestic Control Activities in the Cities of Dar Es Salaam and Tanga

Academic journal article Bulletin of the World Health Organization

Knowledge of Mosquitos in Relation to Public and Domestic Control Activities in the Cities of Dar Es Salaam and Tanga

Article excerpt

Introduction

Most organized mosquito control strategies require public support of one kind or another, and the extent of people's cooperation can determine the success or failure of the entire campaign[1]. To be successful and sustainable, therefore, an intervention has to meet the expectations of both the public health planners and the local people.

Community reactions to vector control are greatly influenced by the perceived impact of interventions on insect pests and nuisance-biting[2, 3]. In rural areas of Africa, Anopheles mosquitos are responsible not only for the transmission of malaria and filariasis, but also for most of the nuisance-biting at night. There is therefore no practical need to distinguish between the problems of nuisance-biting and disease transmission. In urban areas, on the other hand, anophelines are relatively rare. This is because they breed in unpolluted breeding sites - sunlit puddles, pools and ricefields in the case of Anopheles gambiae s.l., and swamps in the case of A. funestus. In towns, of course, most such places are either built over or polluted, and organic pollution favours another mosquito, Culex quinquefasciatus, which can transmit filariasis but not malaria parasites. This species breeds abundantly in pit latrines, soakage pits, and in drains blocked by rubbish[4]. Several studies indicate that it greatly outnumbers malaria vectors, often by more than 100 to 1 in African towns and cities[5, 9].

Malaria is none the less an important public health problem, even in towns, firstly because A. gambiae is such an efficient vector, and secondly because urban residents, being less exposed, tend to be less immune than their rural counterparts[10-13]. In Dar es Salaam, for example, malaria reportedly accounts for 13% of outpatient attendances, nearly 10% of admissions, and over 5% of hospital deaths.(a)

The contrast between the mosquitos of urban and rural areas turns out to be a mixed blessing for urban health planners. On the one hand, Anopheles breeding sites in urban areas tend to be fewer, easier to identify and more accessible than those in the countryside, and well-targeted attacks can therefore achieve a worthwhile degree of control; this would be unthinkable in most rural areas, where breeding sites, are numerous, shifting, and scattered all over the countryside. The good news for town dwellers, therefore, is that malaria is potentially more manageable by environmental control measures in towns than in the country. The bad news is that actions directed against urban malaria vectors will usually have little effect on nuisance-biting, which in towns is mainly due to other mosquitos breeding in other places.

Nevertheless, malaria takes precedence over all other mosquito-related problems, from the point of view of public health authorities[14]. Do residents share this sense of priority? This question was recently addressed by an Urban Malaria Control Project (UMCP), which has been carrying out chemical larviciding and residual house-spraying against malaria vector mosquitos in the cities of Dar es Salaam and Tanga in the United Republic of Tanzania. By 1990, there were already signs in the press and elsewhere that public support for mosquito control efforts was warning. Project staff noted that "people are becoming reluctant and uncooperative in the question of self-help, leading to minimal community participation in vector control, e.g., clearing drains, taking out their goods during residual house spraying, etc." (unpublished report of the UMCP, 1990). One suggested explanation for this lack of support was that residents had seen no reduction in nuisance-biting.

We therefore undertook a qualitative study of the knowledge, attitudes and practice of residents towards mosquitos and mosquito control measures. Our methods and findings are described in this article.

Methods

Study areas

Dar es Salaam and Tanga are both located on the Tanzanian coast. …

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