The mosquito Anopheles (Cellia) oreios sp. n., formerly species 6 of the Australasian Anopheles farauti complex, and a critical review of its biology and relation to disease.

Species 6 of the Australasian Anopheles farauti sibling species complex (Diptera: Culicidae) is described and formally named Anopheles oreios Bangs & Harbach, sp. n. Adult, pupal and fourth-instar larval specimens collected in the Baliem Valley, Papua Province, Indonesia, are characterized and compared with those of Anopheles farauti, Anopheles hinesorum, Anopheles irenicus and Anopheles torresiensis (formerly informally denoted as species 1, 2, 7 and 3, respectively). The variable wings of adult females, the male genitalia, the pupa and the fourth-instar larva of An. oreios are illustrated and DNA sequence data are included for regions coding for sections of the mitochondrial COI and COII genes. The biology of An. oreios and its relation to malaria transmission are discussed in detail and contrasted with the biology and disease relations of some members of the An. farauti and Anopheles punctulatus sibling species complexes.

Field evaluations of disposable sticky lures for surveillance of Aedes aegypti (Stegomyia aegypti) and Culex quinquefasciatus in Jakarta.

From December 1997 to April 1998, disposable sticky lures (1608 lure days) were trialled in homes in north Jakarta, Indonesia as surveillance tools for Aedes aegypti (Stegomyia aegypti) (Diptera: Culicidae) and Culex quinquefasciatus (Diptera: Culicidae), referenced to indoor resting adult collections (92 × 10 min). The lures collected 89.4% of the total of 1339 Ae. aegypti and 92.1% of the total of 1272 Cx. quinquefasciatus collected by all methods. Because there were no significant differences with respect to numbers collected in bedrooms, living rooms and kitchens, bedrooms were selected for subsequent trials for reasons of convenience. The main trials involved a replicated complete block design with L-lysine and sodium carbonate. Lures without attractant or with four different dilutions of L-lysine collected 3.4-8.5 times more Ae. aegypti and 4.2-8.1 times more Cx. quinquefasciatus than were collected by mouth aspirator. Lures with or without dilutions of sodium carbonate collected 2.7-5.0 times more Ae. aegypti and 1.8-4.2 times more Cx. quinquefasciatus than aspirator collections. The precision associated with catches of sticky lures was better than that for aspirator collections. Although olfactants generally improved the numbers of mosquitoes collected, the differences in catch between lures with and without attractants were usually non-significant. Any deficit in catch may be offset by increasing the surveillance period to ≥30 days to detect all four dengue serotypes from infected mosquitoes.

Review on global co-transmission of human Plasmodium species and Wuchereria bancrofti by Anopheles mosquitoes.

Malaria and lymphatic filariasis are two of the most common mosquito-borne parasitic diseases worldwide which can occur as concomitant human infections while also sharing common mosquito vectors. This review presents the most recent available information on the co-transmission of human Plasmodium species and Wuchereria bancrofti by Anopheles mosquitoes. Important biological and epidemiological aspects are also described including the lifecycle of each parasite species and their specificities, the geographical biodiversity of each pathogen and their vectors where the parasites are co-endemic, and biological, environmental and climatic determinants influencing transmission. The co-transmission of each disease is illustrated from both a global perspective and a country level using Thailand as a study case. Different diagnostic methods are provided for the detection of the parasites in biological samples ranging from traditional to more recent molecular methods, including methodologies employing concomitant detection assays of W. bancrofti and Plasmodium spp. parasites. The relevant issues of combined malaria and Bancroftian filariasis control strategies are reviewed and discussed.

Mitochondrial diversity of Musca domestica housefly populations in the Asian and western Pacific biogeographical regions.

Houseflies (Musca domestica L., Diptera: Muscidae) are cosmopolitan, colonizing, and eusynanthropic. Their distribution in the Malaysian archipelago provides an opportunity to study successive waves of colonization and extinction during the Pleistocene and Recent epochs. We scored single-strand conformation polymorphisms (SSCPs) at 16S2 and COII mitochondrial loci in 47 housefly samples from the Australian, Austro-Malayan, Indo-Malayan, Manchurian and Indo-Chinese subregions of Wallace's zoogeographical classification. We discuss the results in light of the Pleistocene vs. post-Pleistocene dispersal and faunal exchange in the Asia-Pacific area. Fourteen haplotypes were detected, of which 10 were confined to a single subregion. No haplotype was ubiquitous and only one was found in four subregions. Population diversity, HS, was greatest in the Indo-Malayan (0.36) and heterogeneous among subregions. The mean subregional diversity was 0.21 +/- 0.03, representing the probability that two randomly chosen flies, from any subregion, had different haplotypes. The hierarchical partition of diversity indicated restricted maternal gene flow among subregions (GRT = 0.60, Nm approximately 0.32). These results suggest long-standing genetic isolation of houseflies in the Malaysian archipelago and support the hypothesis that they dispersed widely during the Pleistocene. Haplotypes common among mainland populations but shared with island groups in low frequencies (<1%) indicate surprisingly little recent gene flow.

Onset of clinical immunity to Plasmodium falciparum among Javanese migrants to Indonesian Papua.

Onset of clinical immunity to Plasmodium falciparum occurred among Javanese migrants to Indonesian Papua. Surveillance of the 243 migrants investigated began on the day of their arrival in Indonesian Papua and continued for 33 months. Asexual parasitaemia without fever constituted objective evidence of clinical immunity. Compared with first infection, the odds ratio (OR) for not having fever at the fourth infection within 24 months was 3.2 [95% confidence interval (CI)=1.03-10.2; P=0.02]. The corresponding OR with fewer infections within 24 months was not distinguishable from 1.0. The level of the fourth parasitaemia within 24 months (N=58) was classified as 'high' or 'low' in relation to the median count at first infection (840 parasites/microl; N=187). Fourth parasitaemias that were low-but not those that were high (OR=1.8; CI=0.6-5.4; P=0.35)-were associated with dramatic protection from fever (OR=31; CI=3.5-1348; P=0.0001). Among the adult subjects, the risk of fever with low parasitaemia was significantly higher at the first infection than at the fourth (OR=12.6; CI=1.7-530; P=0.005), indicating the development of clinical immunity. A similar but less marked pattern appeared among the children investigated (OR=6.5; CI=0.8-285; P=0.06).

Malaria in a cohort of Javanese migrants to Indonesian Papua.

The epidemiology of infection by Plasmodium falciparum and P. vivax was investigated among Javanese migrants to an endemic region of Papua, Indonesia. A cohort of 243 migrants from Java was followed for malaria in a new settlement village in the endemic Armopa area of north-eastern Papua, beginning on the day each migrant arrived in the village. The subjects were monitored during home visits (three/week) and by the twice-monthly production of bloodsmears that were checked for malarial parasites. At the end of 33 months, 159 (65%) of the subjects remained under follow-up. The prevalence of parasitaemia in the village declined from 16% among those already living there when the study began in August 1996, to 5% when the study finished in June 1999. Over this period, 596 infections by P. falciparum and 723 by P. vivax occurred in the cohort, 22 and 27 of the subjects each experiencing at least six infections by P. falciparum and P. vivax, respectively. The incidence of malarial infection was higher during the first and second years post-migration (3.2 and 2.7 infections/person-year) than during the third (1.2 infections/person-year). Although the geometric mean parasite counts for P. falciparum increased over time (1209, 1478, and 1830 parasites/microl in the first, second and third years, respectively), the corresponding values for P. vivax (497, 535 and 490 parasites/microl) showed no such trend. Only one of the nine subjects who developed severe malaria (requiring intravenous quinine therapy) was a child, giving an odds ratio for a case of severe malaria being in an adult of 6.1 (P=0.08).

Primary infection by Plasmodium falciparum or P. vivax in a cohort of Javanese migrants to Indonesian Papua.

The clinical and parasitological characteristics of the first naturally acquired malarial infection have rarely been documented in humans. When 243 migrants from non-endemic Java were followed from the day of their arrival in Indonesian Papua, 217 (89%) were found to become infected with Plasmodium falciparum and/or P. vivax before they were lost to follow-up. The incidence of malarial infection in the children investigated (who were aged 6-10 years) was indistinguishable from that in the adults (aged >20 years), with 1.10 and 1.14 P. falciparum infections/person-year (relative risk=0.97; 95% confidence interval=0.72-1.29) and 1.47 and 1.49 P. vivax infections/person-year (relative risk=0.99; 95% confidence interval=0.72-1.29), respectively. During their first infections, the children had higher P. falciparum parasitaemias than the adults (with geometric means of 1318 and 759 parasites/microl, respectively; P=0.04) but similar P. vivax parasitaemias (with geometric means of 355 and 331 parasites/microl, respectively; P=0.76). At first infection, 56% of the subjects were febrile and 90% complained of symptoms. There were no differences between children and adults with respect to these two parameters, either for P. falciparum or P. vivax. These findings indicate that, with promptly diagnosed and treated uncomplicated malaria, migrant children and adults in north-eastern Indonesian Papua have an equal risk of malarial infection and of disease following their first infections with P. falciparum and P. vivax.

Extensive multiple test centre evaluation of the VecTest malaria antigen panel assay.

To determine which species and populations of Anopheles transmit malaria in any given situation, immunological assays for malaria sporozoite antigen can replace traditional microscopical examination of freshly dissected Anopheles. We developed a wicking assay for use with mosquitoes that identifies the presence or absence of specific peptide epitopes of circumsporozoite (CS) protein of Plasmodium falciparum and two strains of Plasmodium vivax (variants 210 and 247). The resulting assay (VecTest Malaria) is a rapid, one-step procedure using a 'dipstick' test strip capable of detecting and distinguishing between P. falciparum and P. vivax infections in mosquitoes. The objective of the present study was to test the efficacy, sensitivity, stability and field-user acceptability of this wicking dipstick assay. In collaboration with 16 test centres world-wide, we evaluated more than 40 000 units of this assay, comparing it to the standard CS ELISA. The 'VecTest Malaria' was found to show 92% sensitivity and 98.1% specificity, with 97.8% accuracy overall. In accelerated storage tests, the dipsticks remained stable for > 15 weeks in dry conditions up to 45 degrees C and in humid conditions up to 37 degrees C. Evidently, this quick and easy dipstick test performs at an acceptable level of reliability and offers practical advantages for field workers needing to make rapid surveys of malaria vectors.

The drug sensitivity and transmission dynamics of human malaria on Nias Island, North Sumatra, Indonesia.

Nias Island, off the north-western coast of Sumatra, Indonesia, was one of the first locations in which chloroquine-resistant Plasmodium vivax malaria was reported. This resistance is of particular concern because its ancient megalithic culture and the outstanding surfing conditions make the island a popular tourist destination. International travel to and from the island could rapidly spread chloroquine-resistant strains of P. vivax across the planet. The threat posed by such strains, locally and internationally, has led to the routine and periodic re-assessment of the efficacy of antimalarial drugs and transmission potential on the island. Active case detection identified malaria in 124 (17%) of 710 local residents whereas passive case detection, at the central health clinic, confirmed malaria in 77 (44%) of 173 cases of presumed 'clinical malaria'. Informed consenting volunteers who had malarial parasitaemias were treated, according to the Indonesian Ministry of Health's recommendations, with sulfadoxine-pyrimethamine (SP) on day 0 (for P. falciparum) or with chloroquine (CQ) on days 0, 1 and 2 (for P. vivax). Each volunteer was then monitored for clinical and parasite response until day 28. Recurrent parasitaemia by day 28 treatment was seen in 29 (83%) of the 35 P. falciparum cases given SP (14, 11 and four cases showing RI, RII and RIII resistance, respectively). Recurrent parasitaemia was also observed, between day 11 and day 21, in six (21%) of the 28 P. vivax cases given CQ. Although the results of quantitative analysis confirmed only low prevalences of CQ-resistant P. vivax malaria, the prevalence of SP resistance among the P. falciparum cases was among the highest seen in Indonesia. When the parasites present in the volunteers with P. falciparum infections were genotyped, mutations associated with pyrimethamine resistance were found at high frequency in the dhfr gene but there was no evidence of selection for sulfadoxine resistance in the dhps gene. Night-biting mosquitoes were surveyed by human landing collections and tested for sporozoite infection. Among the five species of human-biting anophelines collected, Anopheles sundaicus was dominant (68%) and the only species found to be infective--two (1.2%) of 167 females being found carrying P. vivax sporozoites. The risk of malarial infection for humans on Nias was considered high because of the abundance of asymptomatic carriers, the reduced effectiveness of the available antimalarial drugs, and the biting and infection 'rates' of the local An. sundaicus.

Chloroquine or sulfadoxine-pyrimethamine for the treatment of uncomplicated, Plasmodium falciparum malaria during an epidemic in Central Java, Indonesia.

A recent malaria epidemic in the Menoreh Hills of Central Java has increased concern about the re-emergence of endemic malaria on Java, which threatens the island's 120 million residents. A 28-day, in-vivo test of the efficacy of treatment of malaria with antimalarial drugs was conducted among 167 villagers in the Menoreh Hills. The treatments investigated, chloroquine (CQ) and sulfadoxine-pyrimethamine (SP), constitute, respectively, the first- and second-line treatments for uncomplicated malaria in Indonesia. The prevalence of malaria among 1389 residents screened prior to enrollment was 33%. Treatment outcomes were assessed by microscopical diagnoses, PCR-based confirmation of the diagnoses, measurement of the whole-blood concentrations of CQ and desethylchloroquine (DCQ), and identification of the Plasmodium falciparum genotypes. The 28-day cumulative incidences of therapeutic failure for CQ and SP were, respectively, 47% (N = 36) and 22% (N = 50) in the treatment of P. falciparum, and 18% (N = 77) and 67% (N = 6) in the treatment of P. vivax. Chloroquine was thus an ineffective therapy for P. falciparum malaria, and the presence of CQ-resistant P. vivax and SP-resistant P. falciparum will further compromise efforts to control resurgent malaria on Java.

Randomized, parallel placebo-controlled trial of primaquine for malaria prophylaxis in Papua, Indonesia.

Malaria causes illness or death in unprotected travelers. Primaquine prevents malaria by attacking liver-stage parasites, a property distinguishing it from most chemoprophylactics and obviating 4-week postexposure dosing. A daily adult regimen of 30 mg primaquine prevented malaria caused by Plasmodium falciparum and P. vivax for 20 weeks in 95 of 97 glucose-6-phosphate dehydrogenase (G6PD)-normal Javanese transmigrants in Papua, Indonesia. In comparison, 37 of 149 subjects taking placebo in a parallel trial became parasitemic. The protective efficacy of primaquine against malaria was 93% (95% confidence interval [CI] 71%-98%); against P. falciparum it was 88% (95% CI 48%-97%), and >92% for P. vivax (95% CI >37%-99%). Primaquine was as well tolerated as placebo. Mild methemoglobinemia (mean of 3.4%) returned to normal within 2 weeks. Blood chemistry and hematological parameters revealed no evidence of toxicity. Good safety, tolerance, and efficacy, along with key advantages in dosing requirements, make primaquine an excellent drug for preventing malaria in nonpregnant, G6PD-normal travelers.

Detection of dengue viral RNA in Aedes aegypti (Diptera: Culicidae) exposed to sticky lures using reverse-transcriptase polymerase chain reaction.

Active surveillance for dengue (DEN) virus infected mosquitoes can be an effective way to predict the risk of dengue infection in a given area. However, doing so may pose logistical problems if mosquitoes must be kept alive or frozen fresh to detect DEN virus. In an attempt to simplify mosquito processing, we evaluated the usefulness of a sticky lure and a seminested reverse-transcriptase polymerase chain reaction assay (RT-PCR) for detecting DEN virus RNA under laboratory conditions using experimentally infected Aedes aegypti (L.) mosquitoes. In the first experiment, 40 male mosquitoes were inoculated with 0.13 microl of a 10(4) pfu/ml DEN-2 stock solution. After a 7-d incubation period, the mosquitoes were applied to the sticky lure and kept at room temperatures of 23-30 degrees C. Following 7, 10, 14, and 28 d application, 10 mosquitoes each were removed from the lure, pooled, and assayed for virus. DEN virus nucleic acid was clearly detectable in all pools up to 28 d after death. A second study evaluated sensitivity and specificity using one, two, and five DEN-infected mosquitoes removed after 7,10, 14, 21, and 30 d application and tested by RT-PCR. All four DEN serotypes were individually inoculated in mosquitoes and evaluated using the same procedures as experiment 1. The four serotypes were detectable in as few as one mosquito 30 d after applications to the lure with no evidence of cross-reactivity. The combination of sticky lures and RT-PCR show promise for mosquito and dengue virus surveillance and warrant further evaluation.

Epidemic dengue transmission in southern Sumatra, Indonesia.

An outbreak of dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS) in the city of Palembang, south Sumatra, Indonesia was investigated to (i) validate epidemic occurrence, (ii) confirm dengue virus aetiology and associated serotype(s), (iii) provide a demonstrable measure of community impact, and (iv) identify causative relationship (if any) with climatic El Niño Southern Oscillation (ENSO) influences. Trend analysis based on a 6-year retrospective review of hospital records demonstrates a 3-fold increase in clinical cases for the outbreak period (January-April 1998), relative to historical records. In the 2 hospitals surveyed, the monthly mean number of outbreak-related dengue cases over 4 months was 833 (range 650-995 cases/month); the mean monthly value for the previous 72 months was 107 (range 14-779 cases/month). An apparent trend in epidemic transmission was observed, evolving from a 5-year cyclic phenomenon to an annual occurrence, often indistinguishable from one year to the next. The proportional distribution of clinical outbreak cases into DF, DHF and DSS diagnostic categories was 24%, 66%, and 10%, respectively. The population aged 10-19 years accounted for the largest (35%) proportion of hospitalized DHF cases, followed by children aged 5-9 years (25%) and children aged 4 years (16%). Serum samples obtained during acute illness from 221 hospitalized patients were examined using serology, RT-PCR, and virus isolation in cell culture: 59% of samples had laboratory evidence of a dengue infection. All 4 dengue virus serotypes (DEN 1-4) were identified in epidemic circulation, with DEN 3 predominating (43%). DEN 1 was the principal serotype associated with less severe dengue illness, suggesting that virulence may be, in part, a function of infecting serotype. The climatic influence of ENSO on rainfall and temperature in the months leading up to and during the outbreak was dramatic, and is likely to contribute to favourable outbreak conditions.

Effects of nutritional and physiological status on behavioral avoidance of Anopheles minimus (Diptera: Culicidae) to DDT, deltamethrin and lambdacyhalothrin.

The monitoring of behavioral responses of mosquitoes to insecticides are critical to the understanding of how chemicals function in the control of disease transmission. The excito-repellency avoidance responses of laboratory-reared Anopheles minimus females exposed to diagnostic concentrations of DDT (2 g/m2), deltamethrin (0.0625 g/m2), and lambdacyhalothrin (0.0369 g/m2) were observed using an excito-repellency escape chamber. Insecticide contact (measuring irritancy) and non-contact (measuring repellency) behavioral assays were conducted on non-blood-fed (unfed), sugar-fed, early blood-fed (recently engorged) and late blood-fed mosquitoes. Rates of escape from the contact and non-contact chambers, regardless of chemical compounds, were most dramatic in unfed mosquitoes compared to other nutritional states (P < 0.05). In general, across all 3 chemicals, slower escape response was observed in sugar-fed and early blood-fed specimens, whereas late blood-fed showed an intermediate response. Relative suppression of escape flight response in comparison to matched non-insecticide treated controls and the unfed condition is likely the result of normal reduced flight activity among recent blood and sugar-engorged mosquitoes. We conclude that nutritional states and physiological conditions of mosquitoes as a result of blood feeding can dramatically influence excito-repellency test results. Therefore, for interpretive purposes, studies on chemical irritancy and repellency must account and control for the inherent variability of avoidance responses to insecticides influenced by nutritional and physiological conditions of the mosquitoes at the time of test.

Rediscovery of Anopheles (Cellia) clowi (Diptera: Culicidae), a rarely recorded member of the Anopheles punctulatus group.

Anopheline specimens collected in Papua New Guinea were morphologically identified as the rarely recorded Anopheles clowi Rozeboom & Knight. Amplification of the rDNA ITS2 region of this material revealed a fragment of 750 bp confirming its placement in the Anopheles punctulatus group. This group contains 12 species and includes the major malaria vectors in the islands of the southwest Pacific. Digestion of the ITS2 with the restriction enzyme MspI produced restriction fragment-length polymorphism with bands at 380, 300, and 150 bp, a pattern shared by no other members of this group. Phylogenetic analysis involving the sequencing of a 2 kb region of the rDNA 18S gene indicated that An. clowi was monophyletic and basal to the rest of the group and showed considerable independent evolution from the other members. This is the first record of An. clowi in Papua New Guinea and only the third collection of this species since its discovery in 1945.

Status of malaria in Thailand.

Despite decades of control success and a competent network of country-wide health infrastructure, malaria remains an important health threat in rural Thailand. All 4 known human malaria parasites have been reported present, with Plasmodium falciparum and Plasmodium vivax predominant. The expansion and intensity of multi-drug resistant Plasmodium falciparum is the most serious development to occur the last several decades. Members of 3 anopheline species complexes, Anopheles dirus, Anopheles minimus, and Anopheles manculatus, are considered to be primary malaria vectors in the country. Representatives within all 3 taxa are difficult or impossible to separate morphologically from one another, and insufficient information exists about population genetics between sibling species and vector status. Vector control in Thailand has been the primary means of malaria control, mainly by the use of routine residual insecticide spray inside houses. The use of DDT in vector control has resulted in measurable successes to interrupt malaria transmission in many parts of the country. Since 1949, DDT has been the predominant compound used: however, its public health use has continued to decline as a result of perceived operational difficulties, political issues and environmental concerns. The increased use of pyrethroids to impregnate bednets and for intradomiciliary spraying are generally more accepted by rural populations and are rapidly replacing the use of DDT. Organized malaria control activities have reduced malaria morbidity from 286/1,000 population in 1947 to 1.5/1,000 population by 1996. Despite encouraging trends in dramatically reducing malaria, the rates of disease may be re-emerging in the country as evidence from an increased annual parasite index from 1.78/1,000 in 1997 to 2.21 in 1998. The possible reasons for the apparent increase in incidence are discussed in terms of the technical, operational and social obstacles in malaria control in Thailand.

Plasmodium vivax polymorphs and Plasmodium falciparum circumsporozoite proteins in Anopheles (Diptera: Culicidae) from Belize, Central America.

Eight species of Anopheles mosquitoes from indoor/outdoor human landing collections in Belize, Central America, were examined for human Plasmodium circumsporozoite protein (CSP) using an enzyme-linked immunosorbent assay (ELISA). A total of 14 of 9,104 females tested were positive from general surveys throughout Belize and three of 11,966 were positive from a longitudinal study in Caledonia, northern Belize. ELISA results, using pooled head-thorax preparations and species-specific monoclonal antibodies directed against the circumsporozoite proteins of Plasmodium falciparum and two Plasmodium vivax polymorphs (210 and VK247), found four species reactive: Anopheles vestitipennis (3 pools), Anopheles darlingi (2 pools), Anopheles albimanus (10 pools), and Anopheles gabaldoni (2 pools). The minimum field infection rates (MFIR) for combined Plasmodium species from the general survey were 0.282% for An. vestitipennis, 0.271% for An. darlingi, 0.126% for An. albimanus, and 0.395% for An. gabaldoni. MFIRs for combined Plasmodium species from the longitudinal study in the village of Caledonia were 0.018% for both An. vestitipennis and An. albimanus and 1.66% for An. gabaldoni. Positive CSP pools were collected from the Cayo, Corozal, Orange Walk, Stann Creek, and Toledo political districts. No CSP positive pools were detected from collections in the Belize District. The study provides valuable information on the spatial distribution and species type of Plasmodium positive mosquitoes. This information, in combination with other vector data, suggest that An. vestitipennis and An. darlingi are commonly involved in malaria transmission. Additionally, these species appear to be much more efficient vectors than An. albimanus in Belize.

Use of a funnel trap for collecting immature Aedes aegypti and copepods from deep wells in Yogyakarta, Indonesia.

During the course of a "dry" season dengue vector survey, indoor and outdoor household wells were sampled for the possible presence of immature mosquitoes and copepods. With a simple floating funnel trap, Aedes aegypti immature stages were captured in over 33% of the sampled wells (n = 93) during a 24-h trapping period per well. Average number of larvae (all instars) per positive well was 8.8 (range 1-63). Positive wells varied in depth from 2.7 to 14.7 m (8.8-48.2 ft), with a mean of 7.9 +/-SE 0.5 m in well rim to water surface. Only 4 wells (4.3%) contained Culex quinquefasciatus larvae. Only 1 of 31 infested wells contained both species. Aedes albopictus was not detected in any of the wells. Cyclopoid copepods were captured in 15% of the wells. No significant difference was found between positive and negative wells with regard to the physical characteristics (inside diameter, distance to water level) or the depth and volume of water held at the time of sampling. A significant association was found between wells positive for larvae and numbers of other positive containers in the vicinity of the wells. In general, wells containing copepods had fewer larvae present in the trap, possibly indicating some level of natural population regulation of Ae. aegypti occurring in the well; however, this association was not significant. Preliminary results indicate that wells in Yogyakarta serve as important permanent habitats for Ae. aegypti, especially during the dry season.

Rare quadruple malaria infection in Irian Jaya Indonesia.

We report an exceptional finding from a blood slide collected in a remote area in the western half of New Guinea Island (Irian Jaya Province, Indonesia). One adolescent patient was found patently coinfected with all 4 known human malaria species, Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale. Diagnostic erythrocytic stages of all 4 species were clearly seen in the peripheral blood. A nested polymerase chain reaction, using species-specific primer pairs to detect DNA, helped substantiate this finding. Previous reports from Africa, Thailand, and New Guinea have detected all 4 species in a population but not simultaneously in an individual with a patent, microscopically detectable infection. We believe this quadruple infection represents the first reported natural case of all 4 human malaria parasites observed concurrently in the peripheral blood from a single Giemsa-stained slide.

In vivo responses to antimalarials by Plasmodium falciparum and Plasmodium vivax from isolated Gag Island off northwest Irian Jaya, Indonesia.

There is renewed interest in the rich nickel and cobalt deposits of Pulau Gag, an isolated but malarious island off the northwest coast of Irian Jaya. In preparation for an expanded workforce, an environmental assessment of malaria risk was made, focusing upon malaria prevalence in the small indigenous population, and the in vivo sensitivity of Plasmodium falciparum and P. vivax to chloroquine (CQ) and sulfadoxine/pyrimethamine (S/P), the respective first- and second-line drugs for uncomplicated malaria in Indonesia. During April-June 1997, mildly symptomatic or asymptomatic malaria infections were found in 24% of 456 native residents. Infections by P. falciparum accounted for 60% of the cases. Respective day 28 cure rates for CQ (10 mg base/kg on days 0 and 1; 5 mg/kg on day 2) in children and adults were 14% and 55% (P < 0.005). Type RII and RIII resistance characterized only 5% of the CQ failures. Re-treatment of 36 P. falciparum CQ treatment failures with S/P (25 mg/kg and 1.25 mg/kg, respectively) demonstrated rapid clearance and complete sensitivity during the 28-day follow-up period. More than 97% of the P. vivax malaria cases treated with CQ cleared parasitemia within 48 hr. Three cases of P. vivax malaria recurred between days 21 and 28, but against low drug levels in the blood. The low frequency of RII and RIII P. falciparum resistance to CQ, the complete sensitivity of this species to S/P, and the absence of CQ resistance by P. vivax are in contrast to in vivo and in vitro test results from sites on mainland Irian Jaya.