Malaria eradication on islands

doi:10.1016/S0140-6736(00)03127-5

The Lancet

Volume 356, Issue 9241, 4 November 2000, Pages 1560-1564

https://doi.org/10.1016/S0140-6736(00)03127-5 Get rights and content

Summary

Background

To be successful, a malaria control programme needs to be tailored to the local epidemiological characteristics. Vanuatu consists of 80 inhabited islands in the Southwest Pacific, with hypoendemic and mesoendemic malaria and suitable conditions for sustained parasite elimination. We aimed to assess whether malaria can be eliminated on isolated islands.

Methods

Weekly mass drug administration of chloroquine, pyrimethamine/sulfadoxine (Fansidar), and primaquine was carried out on the entire population of 718 inhabitants of Aneityum island for 9 weeks in 1991 before the onset of the rainy season. Simultaneously with the administration of drugs, permethrin-impregnated bednets were distributed to the entire population. Larvivorous fish were also introduced into several identified breeding sites of Anopheles farauti. Periodic malariometric monitoring has continued for the past 9 years. Two additional islands of Vanuatu, one with and one without malaria transmission, have been monitored for comparison.

Findings

High community involvement as measured by drug compliance (88·3%) and bednet provision (0·94 nets per villager) has resulted in sustained interruption of malaria transmission in Aneityum. The surveys showed complete absence of Plasmodium falciparum after mass drug administration, and P vivax disappeared from 1996 onwards, with the exception of two instances of imported infections (one mixed infection in 1993 and one P vivax infection in 1999).

Interpretation

Malaria can be eliminated on isolated islands with well-adapted short-term mass drug administration and sustained vector control if there is a high degree of community participation.

Introduction

Despite 50 years of malaria control efforts, malaria remains one of the main global public-health issues. A new global initiative, Roll Back Malaria, has recently been launched,¹ but existing tools for malaria control are limited. Specific tools such as the distribution of insecticide-impregnated bednets need to be reinforced and new strategies for case management need to be implemented, especially at peripheral levels. Successful malaria control requires an understanding of the local epidemiological characteristics in order to select and determine appropriate countermeasures.

Vanuatu consists of 80 inhabited islands in the Southwest Pacific at the southeast margin of the malarious band extending from Southeast Asia to Melanesia. Malaria is hypoendemic to mesoendemic and seasonal on most populated islands with occasional hyperendemic periods on some islands. Plasmodium falciparum and P vivax infections are common whereas P malariae is rare. The peak incidence of clinical P falciparum cases occurs during the rainy season (December to May).² The only identified malaria vector is Anopheles farauti.3, 4, 5

In vivo resistance of P falciparum to chloroquine was about 30% in 1990, whereas resistance to pyrimethamine/sulfadoxine (Fansidar) has remained rare. Chloroquine is, however, still the drug of choice for malaria in adults and older children, whereas Fansidar is recommended for children less than 5 years of age.⁶

Residual house spraying with DDT (1,1,1-trichloro-2,2 bis [parachlorophenyl] ethane) was introduced and implemented on eight islands in 1973, but an assessment in 1982 provided no clear evidence of an effect on prevalence of malaria. The most likely reasons for the failure were poor implementation and consumer resistance. The spraying programme was therefore withdrawn and only focal spraying remained to prevent outbreaks.

The isolated island environment of Vanuatu, however, is suitable for intervention measures leading to the sustained lowering or even elimination of the parasite reservoir. Aneityum, a malaria-endemic island with 718 inhabitants concentrated in three major villages, was therefore selected as a study island for a new combined control strategy. Mass drug administration was done for 9 weeks prior to the rainy season, permethrin-impregnated bednets were distributed to the entire population, and larvivorous fish were introduced into identified breeding sites of A farauti. We have continued to monitor the malariometric effects of this intervention throughout the 9-year period following its introduction.

Section snippets

Setting and participants

Aneityum was selected as the study island for the intervention package. Aneityum is a circular island of volcanic origin, and mountainous with wooded peaks rising to 850 metres. Aneityum has abundant streams and swampy valleys, which serve as larval habitat for A farauti. The total population of 718 people live in and around three villages: Analgaut, Port Patrick, and Unmet. The entire population of Aneityum island was included in the study. Health care for the island is provided by a

Intervention

The 718 inhabitants of Aneityum were registered in the records of mass drug administration kept by the district malaria supervisor during the drug intervention period. Of 6462 scheduled drug doses, 509 (7·9%) were not administered because of villagers' absence from the island, and the intake of a further 247 (3·8%) doses was not properly recorded and could not be confirmed. Of the remaining 5706 scheduled doses, 5038 were successfully administered during the nine mass drug administration

Discussion

The prevalence of malaria on Aneityum dramatically decreased after initiation of the intervention programme and we believe that Aneityum has been malaria-free since 1997, with one exception. Before the intervention the malaria situation or Aneityum showed a pattern similar to that of Malakula. In recent years the situation on Aneityum, however, has become similar to that of Futuna. Since malaria transmission was not reduced on Malakula, we are convinced that the change on Aneityum was a result

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ArticlesMalaria eradication on islands

Summary

Background

Methods

Findings

Interpretation

Introduction

Section snippets

Setting and participants

Intervention

Discussion

Acta Trop

Lancet

Lancet

The "Roll Back Malaria" campaign

Science

Sur des Culicides des Nouvelles-Hébrides

Comptes Rendus de la Société de Biologie

Anopheline mosquitoes of the Solomon Islands and New Hebrides

J Parasitol

Malaria treatment in Vanuatu: new national treatment guidelines

PNG Med J

A malaria survey of Futuna in the New Hebrides

J Trop Med Hyg

Terminology of malaria and of malaria eradication

The effect of continuous and intermittent primaquine therapy on the relapse rate of Chesson strain vivax malaria

J Lab Clin Med

Chemotherapy and drug resistance in malaria

Studies in human malaria: a summary of 204 sporozoite-induced infections with the Chesson strain of Plasmodium vivax

J Nat Malaria Soc

Articles
Malaria eradication on islands