Malaria in North Sulawesi, Indonesia

The incidence and impact of malaria in North Sulawesi have declined both in the short term during the 1990s, and over a much longer timespan (though perhaps less continuously) since the end of the colonial period. The improvement already seems to have been well underway before deliberate vector control activities became extensive in the second half of the 1970s, and environmental changes affecting the Anopheles mosquito fauna, in particular the replacement of primary and secondary forest by permanent farmland, are probably the principal reasons for the long-term trend; other possible factors include the increasing use of antimalarial drugs. The welldocumented decline in malaria incidence over the years 1991-1997, nevertheless, probably reflects the unprecedented scale of residual insecticide spraying in the province during that period, while the slight resurgence of the disease in the last three years corresponds to the subsequent cessation of house spraying as a result of the current economic crisis. Despite the evident importance of environmental change as a factor ameliorating the malaria situation in the long term, experience from the colonial era suggests that the prospects for deliberate environmental management (species sanitation) as an alternative malaria control strategy are poor. Correspondence: D Henley, KITLV, PO Box 9515, 2300 RA Leiden, Netherlands. Fax: +(31 71) 5272638; E-mail: [email protected] SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH Vol 32 No. 3 September 2001 596 effective, strategies for malaria control. Residual insecticide spraying, even when DDT was still available, was expensive, consuming approximately 70% of the total malaria control budget (HA Marwoto, interview, 11/8/00), and under the present circumstances a drastic reduction in this particular pratice is inevitable. A shift to alternative strategies is also supported by the current WHO guidelines for malaria control, which since 1993 have deemphasized insecticide use in favor of early diagnosis, prompt and universal medical treatment of sufferers, personal protection (particularly the use of bed nets), and more selective programs of vector control, including various types of biological and environmental management aimed at eliminating local mosquito breeding sites (WHO, 1993). In many respects the proposed new strategy recalls that followed with some success in Indonesia during the late colonial period, when the Dutch authorities relied for malaria control on environmental “species sanitation” measures (Snellen, 1990) combined with the distribution of antimalarial medicine (quinine) and mosquito nets (Boomgaard, 1987; Netherlands Indies Medical and Sanitary Service, 1929). The current WHO guidelines, on the other hand, were criticized by some as too heavily based on African experience, and too little appreciative of the considerable success achieved in other parts of the world including Java and Bali in Indonesia (Soemarlan and Gandahusada, 1990) by mass insecticide use during the optimistic “malaria eradication” campaigns of the 1950s and 1960s (Baird, 2000; Roberts et al, 1997). Among Indonesian experts there are some who recommend that mosquito control (other than individual protection by means of bed nets and repellants) should now be abandoned altogether except where it can be shown that the local vector population is small and isolated enough to preclude rapid recolonization from neighboring areas. Others, however, believe that attempts must be made to maintain a broad strategy, including the use of insecticides in order to keep the mosquitos out of dwellings. MALARIA IN NORTH SULAWESI North Sulawesi is a mountainous province occupying the terminal section of the northern peninsula of the eponymous island (the kabupaten of Gorontalo, Bolaang-Mongondow and Minahasa), together with the Sangir and Talaud island groups between Sulawesi and the Philippines (Fig 1). A long history of European political intervention, economic involvement, and missionary activity in this region has produced rich archival and other sources which facilitate the reconstruction of past health and medical conditions (Henley, 2001). In colonial times, malaria was usually regarded as the biggest single health problem in this part of Indonesia. Uplanders in nineteenth-century Minahasa, for example, were considered to be risking their lives every time they visited malarial Manado (Riedel, 1872), and on Talaud in 1914 almost half of the population was estimated to be suffering from malaria (Roep, 1917). In 1929, every schoolchild in the coastal settlement of Marisa in Gorontalo had an enlarged spleen (Dutrieux, 1930), and in Bolaang-Mongondow during the 1930s, endemic malaria was blamed for the sparse and apparently declining populations of Bintauna on the north coast and the Dumoga valley in the western interior (Tammes, 1940). Today, although still a common disease, malaria no longer causes the same concern. As many inhabitants of Bolaang-Mongondow died in accidents as of malaria in 1999, while tuberculosis and heart failure were both considerably more important as overall causes of death (Profil kesehatan Bolaang Mongondow 2000). In 1994-1995, malariometric surveys in eight villages of Sangir and Talaud where the number of (clinically identified) malaria sufferers was particularly high found an average parasite rate, among children aged 0-9 years, of 7.4%; in no individual village was the figure higher than 14.3%. In eight reportedly malariaprone Minahasan villages, the equivalent average was 6.9% (Sekar Tuti et al, 1999). These surveys were monochronic, taking no account of seasonal variations, and poor microscopy MALARIA IN NORTH SULAWESI, INDONESIA Vol 32 No. 3 September 2001 597 may also have been a source of distortion. The results of earlier research by investigators from both the US Navy and the Indonesian National Institute of Health Research and Development, however, seem to confirm that a dramatic improvement on the situation in colonial times had already taken place in North Sulawesi by the early 1970s. Out of 2,495 blood smears collected from nine Minahasa and BolaangMongondow villages in 1975, only two contained malaria parasites (Cross et al, 1977); a parallel study of three coastal settlements in Gorontalo found only one malaria infection among 263 blood samples (Stafford et al, 1976). Particularly telling in terms of the “rolling back” of malaria in North Sulawesi since the end of the colonial period has been the success of frontier colonization efforts. Since 1953 approximately 55,000 immigrants have been settled in the province under state-sponsored transmigration schemes (Buku data, 1999), while much intra-provincial migration to the same frontier areas has also occurred. Many of the sites chosen for transmigrant settlement located in areas formerly notorious for malaria. The Paguat area near Marisa, where large numbers of migrant gold miners died of “fevers” every year in the eighteenth and early nineteenth centuries (Henley, 1997), is now home to more than 16,000 state-sponsored transmigrants, and the Paguyaman valley, where attempts to establish commercial sugar production in the 1930s reportedly had to be abandoned as a result of malaria infections among the plantation workers (Korn, 1934), to more than 20,000 (Buku data, 2000). Most dramatic of all has been the transformation of the Dumoga valley of Bolaang Mongondow, the malariaridden population of which in 1930 amounted to some 5,000 souls (Volkstelling, 1936); today more than 60,000 people live in the same area (Bolaang Mongondow dalam angka, 1995), and their prosperous wet rice-farming villages are regarded as rare models of successful transmigration. If a marked decline in malaria prevalence had already occurred between 1930 and 1975, statistical evidence indicates a continuing or renewed decline in the course of the 1990s. For North Sulawesi as a whole, the incidence of clinical malaria (diagnosed on the basis of clinical symptoms only) from 1986 to 1999, according to provincial health service statistics, was as follows (Fig 2). The apparent rise in malaria incidence from 1986 to 1988 may well be an illusion caused by progressively more complete disease reporting, since both the puskesmas (local Fig 1–Map of North Sulawesi, showing administrative divisions in 2000. PROVINCE OF CENTRAL SULAWESI kapaten G O R O N TA LO kapaten B O LA A N G -M O N G O N D O W kapaten M IN A H A S A kabupaten SANGIR-TALAUD