インドネシア・ロンボク島のマラリア浸淫地におけるハマダラカ蚊相とマラリア媒介蚊の究明

A systematic mosquito collection was carried out for 3 years from November 2001 to September 2004 in western Lombok Island, Indonesia to clarify Anopheles fauna, and to confirm vector species in malaria endemic areas. Adult mosquitoes were collected at 14 sites in the study area by using double-walled mesh nets with human or cow bait. A total of 11 species were encountered. Anopheles vagus was the most predominant. The second most abundant species differed among the sub-study areas; An. sundaicus was abundant in the coastal plain area, and An. balabacensis in the mountainous area. Anopheles balabacensis showed high anthropophily and exophagy and An. sundaicus moderate anthropophily and exophagy. Malaria parasite detection from the collected mosquitoes was also carried out through the detection of circumsporozoite protein by the VecTest^. Fourteen and 4 samples, which were positive for Plasmodium falciparum and P. vivax antigen respectively, were found from An. subpictus, An. sundaicus and An. balabacensis. We conclude that malaria in the coastal plain area is transmitted by An. sundaicus and An. subpictus, whereas An. balabacensis is the primary vector in the mountainous area of Lombok Island.2001年11月から2004年9月までインドネシア・ロンボク島・ムニンティング郡においてマラリア媒介蚊調査を行った.合計11種のハマダラカを沿岸,丘陵地,平地,山間部の異なる4地域で採取した.沿岸と山間部で採取した10種について,Vectestを用いてマラリア原虫抗原検出試験を行った結果,森林部で採取したAn.balabacensis,沿岸部で採取したAn.sundaicusとAn.subpictusから陽性反応が得られた.特にAn.balabacensisから多くの陽性反応を得た.これら3種は屋外吸血性,人嗜好性が認められ,マラリア患者との発生時期や分布地域とも一致したため,マラリア媒介蚊と判断した.ロンボク島でのAn.balabacensisによるマラリア媒介は,本研究が初めて明らかにした

Malaria epidemiology and control methods in specific geographical foci in Lombok and Sumbawa islands of Indonesia; (I) epidemiology

Malaria epidemiological surveys were carried out in two subdistricts; Meninting of Lombok island and Utan of Sumbawa island, Indonesia in 2002 through 2003. In Meninting, distribution of hypo- to meso- endemicity was observed mainly in hilly forested areas and partially in coastal areas with no distribution in the more densely populated flat areas surrounded by rice fields. In contrast, in Utan the distribution was limited to the coastal areas. In Utan, treatment follow-up studies revealed the prevalence of chloroquine resistant Plasmodium falciparum (P. f.). Although the degree of malaria endemicity in the two areas was regarded as hypo- to meso-endemic, the majority of affected individuals were under the age of ten, and the number of positive cases declined with increasing age. Interestingly, age dependence to species-specific infection was observed, younger children being more prone to P. vivax infections than to P. f

MALARIA ENDEMIC PATTERNS ON LOMBOK AND SUMBAWA ISLANDS, INDONESIA

Nusa Tengara Barat (NTB) province consists of two main islands, Lombok and Sumbawa, to the east of Bali Island, Indonesia. Most of the area is known to be moderately malaria endemic, but the exact malaria epidemiology has not been elucidated. At least 30 deaths per year are thought to be caused by falciparum malaria in Lombok alone, judging from the hospital data. According to the Gebrak Malaria Team in West Lombok, the annual incidence in the district of West Lombok from 1996 to 1999 was consistently over 40‰. In the present report, we describe the small malaria endemic foci in the West Lombok and Sumbawa districts. Falciparum malaria is predominant over vivax malaria and other types of malaria. There are 11 species of Anopheles vector, but three of these species, An. subpictus, An. maculates and An. barbirostris, are of primary importance in malaria transmission and An. sundaicus and An. aconitus are of secondary importance. Our data from Sekotong, West Lombok, and Sumbawa supported the importance of An. subpictus in coastal areas but suggested the existence of different transmission peaks according to environmental conditions. The usual transmission peak comes in the dry season but is affected by climatic and geographical conditions. Although there were many malaria endemic foci along the coast, the width and grade of the foci varied widely. The presence of malaria endemic foci inland, although likely, has not been definitively reported to date

Incidences of vaccine-preventable Haemophilus influenzae type b pneumonia and meningitis in Indonesian children: hamlet-randomised vaccine-probe trial.

BACKGROUND: Most studies of Haemophilus influenzae type b (Hib) disease in Asia have found low rates, and few Asian countries use Hib vaccine in routine immunisation programmes. Whether Hib disease truly is rare or whether many cases remain undetected is unclear. METHODS: To estimate incidences of vaccine-preventable Hib pneumonia and meningitis among children younger than 2 years in Lombok, Indonesia, during 1998-2002, we undertook a hamlet-randomised, controlled, double-blind vaccine-probe study (818 hamlets). Children were immunised (WHO schedule) with diphtheria, tetanus, pertussis (DTP) or DTP-PRP-T (Hib conjugate) vaccine. Vaccine-preventable disease incidences were calculated as the difference in rates of clinical outcomes between DTP and DTP-PRP-T groups. Analyses included all children who received at least one vaccine dose. FINDINGS: We enrolled 55073 children: 28147 were assigned DTP-PRP-T and 26926 DTP. The proportion of pneumonia outcomes prevented by vaccine ranged from less than 0 to 4.8%. Calculated incidences of vaccine-preventable Hib disease (per 10(5) child-years of observation) for outcome categories were: substantial alveolar consolidation or effusion, less than zero (-43 [95% CI -185 to 98]); all severe pneumonia, 264 (95% CI less than zero to 629); all clinical pneumonia, 1561 (270 to 2853); confirmed Hib meningitis, 16 (1.4 to 31); meningitis with cerebrospinal-fluid findings consistent with a bacterial aetiology, 67 (22 to 112); and admission for suspected meningitis or presenting to a clinic with convulsions, 158 (42 to 273). INTERPRETATION: Hib vaccine did not prevent the great majority of pneumonia cases, including those with alveolar consolidation. These results do not support a major role for Hib vaccine in overall pneumonia-prevention programmes. Nevertheless, the study identified high incidences of Hib meningitis and pneumonia; inclusion of Hib vaccine in routine infant immunisation programmes in Asia deserves consideration