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.

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.

Performance of the OptiMAL assay for detection and identification of malaria infections in asymptomatic residents of Irian Jaya, Indonesia.

The OptiMAL assay, a new immunochromatographic "dipstick" test for malaria based on detection of Plasmodium lactate dehydrogenase (pLDH), is purported to detect infections of approximately 200 parasites/microL of blood and to differentiate between Plasmodium falciparum and non-P. falciparum. We evaluated OptiMAL performance by comparing the test strip interpretations of two independent readers with consensus results obtained independently by expert malaria microscopists. Unbiased measures of sensitivity were derived by applying the OptiMAL test for detection and differentiation of light, asymptomatic infections by P. falciparum and Plasmodium vivax. OptiMAL readings were separated in time to determine whether the reaction signal was stable. Microscopy identified infections in 225 of 505 individuals screened; those with P. falciparum (n = 170) averaged 354 asexual forms/microL and P. vivax/Plasmodium malariae (n = 112) averaged 216 asexual forms/microL of blood. Concordance between OptiMAL and microscopy was 81% and 78% by the two independent readings. The assay's sensitivity for detection of any malaria species was 60.4% and 70.2% respectively and specificity was 97% and 89%. Most cases identified by microscopy as P. falciparum were graded as negative or non-falciparum by both OptiMAL readers. OptiMAL false negatives as well as misidentifications were related to low parasitemias (< 500/microL). The OptiMAL assay demonstrated 88-92% sensitivity for detecting infections of 500-1,000 parasites/microL, a range covering the mean parasitemia of primary symptomatic P. falciparum infections in malaria-naïve Indonesian transmigrants. This device was markedly less sensitive than expert microscopy for discriminating between malaria species and is presently unsuited for use as an epidemiological screening tool. The OptiMAL assay is not approved for diagnostic use but is commercially available for research purposes only.

Field trials of a rapid test for G6PD deficiency in combination with a rapid diagnosis of malaria.

A rapid single-step screening method for detection of glucose-6-phosphate dehydrogenase (G6 PD) deficiency was evaluated on Halmahera Island, Maluku Province, Indonesia, and in Shan and Mon States, Myanmar, in combination with a rapid diagnosis of malaria by an acridine orange staining method. Severe deficiency was detected by the rapid test in 45 of 1126 volunteers in Indonesia and 54 of 1079 in Myanmar, but it was difficult to distinguish blood samples with mild deficiency from those with normal activity. 89 of 99 severely deficient cases were later confirmed by formazan ring method in the laboratory, but 5 with mild and 5 with no deficiency were misdiagnosed as severe. Of the samples diagnosed as mild and no deficiency on-site, none was found to be severely deficient by the formazan method. Malaria patients were simultaenously++ detected on-site in 273 samples on Halmahera island and 277 samples from Shan and Mon States. In Mon State, primaquine was prescribed safely to G6 PD-normal malaria patients infected with Plasmodium vivax and/or gametocytes of P. falciparum. The new rapid test for G6 PD deficiency may be useful for detecting severe cases under field conditions, and both rapid tests combined are can be useful in malaria-endemic areas, facilitating early diagnosis, prompt and radical treatment of malaria and suppression of malaria transmission.

Humoral immune responses against Plasmodium vivax MSP1 in humans living in a malaria endemic area in Flores, Indonesia.

The aim of this study was to evaluate the relationship among age, parasitemia status, spleen size, hematocrit, and antibody levels to Plasmodium vivax merozoite surface protein 1 (MSP1) in individuals chronically exposed to P. vivax. Subjects were recruited from the population of three adjacent villages on the Island of Flores in Indonesia where malaria transmission is hyperendemic and tropical splenomegaly syndrome is highly prevalent. Subjects were evaluated for spleen size, hematocrit, presence of parasitemia, and presence of antibodies to a recombinant peptide consisting of 90 amino acids from the carboxy terminus of MSP1. Fifty-seven percent of 2-4 year olds, 45% of 5-9 years old, and 7% of > or = 15 years old were parasitemic; 99% of the > or = 15 years old had splenomegaly, and 31% of them had Hackett 4 or 5 spleens. The frequency of antibody positivity to MSP1 antigen in ELISA increased with age reaching a maximum of 89% in > or = 20 years old. The frequency of antibody positivity to MSPI also increased with spleen size, and with a decline in the prevalence of parasitemia.

Survey of in vivo sensitivity to chloroquine by Plasmodium falciparum and P. vivax in Lombok, Indonesia.

A malariometric survey was conducted in 14 villages of Sekotong district, in Lombok, Indonesia during October 1994. Point prevalence of malaria ranged from 0% to 15% in the surveyed villages, averaging 6% overall, and Plasmodium falciparum accounted for 63% of the infections. Forty-nine patients with uncomplicated malaria and parasite counts ranging from 40 to 10,800 asexual forms/microliter were enrolled in a 28-day in vivo test of chloroquine sensitivity. All subjects received a supervised therapeutic regimen of chloroquine (25 mg base/kg over a 48-hr period) and parasitemia and symptoms were closely monitored for 28 days. Asexual parasites were eliminated within four days in the 29 P. falciparum and 20 P. vivax study patients enrolled. The cumulative incidence of therapeutic failure (recurrent symptomatic parasitemia) among P. falciparum cases at days 7, 14, and 28 was 7%, 10%, and 14% (4 of 29), respectively. However in all four cases, parasitemias recurred against chloroquine blood levels below the minimally effective concentration (MEC) of 200 ng/ml and do not confirm chloroquine resistance. All 20 P. vivax parasitemias were sensitive to chloroquine and the blood remained clear, with the exception of one case in which an asymptomatic parasitemia appeared on day 28. Parasitemias by P. falciparum and P. vivax that were observed before supervised therapy, but in the presence of whole blood chloroquine above normally suppressive MEC levels, suggest resistance to suppressive or prophylactic regimens of chloroquine.

Low immunogenicity of a Plasmodium vivax circumsporozoite protein epitope bound by a protective monoclonal antibody.

The repeat region of the Plasmodium vivax circumsporozoite (CS) protein contains 20 copies of the nine-amino acid sequence DRA A/D GQPAG. A monoclonal antibody that passively protects monkeys against sporozoite challenge recognizes a four-amino acid linear sequence AGDR included within this nonamer, but when monkeys were immunized with a vaccine, NS1(81)V20, which contains 20 copies of the nonamer, they failed to produce antibodies to AGDR. To determine if natural exposure to sporozoites induces antibodies to AGDR, we tested sera from 176 individuals from a malaria-endemic area in Flores, Indonesia. Seventy-one percent of the adults had antibodies to the P. vivax repeat region; only 18% had detectable antibodies to AGDR. None of the subjects had antibodies to the P. vivax variant repeat ANGAGNQPG. We next tested sera from six human volunteers immunized with NS1(81)V20 and found that the vaccine, despite inducing antibodies against the nonamer, as it did in the monkeys, did not induce antibodies against AGDR. To further test our ability to raise anti-AGDR antibodies using synthetic peptides, we immunized Aotus monkeys and BALB/c mice with AGDR. Sera from the mice reacted strongly with both AGDR and a recombinant protein containing the 20 copies of the nonamer. Sera from the monkeys reacted only minimally with a protein (VIVAX-1) that contains monomeric AGDR within its sequence. Sera from the mice also bound air-dried P. vivax sporozoites, while sera from the monkeys did not.(ABSTRACT TRUNCATED AT 250 WORDS)

High-dose dexamethasone in quinine-treated patients with cerebral malaria: a double-blind, placebo-controlled trial.

We compared placebo and dexamethasone (initial dose, 3 mg/kg; total, 11.4 mg/kg per 48 h) in a double-blind trial involving 10 stuporous and 28 comatose patients with cerebral malaria. Patients were 18 mo to 42 y of age (geometric mean, 10.2 y), and the 19 patients in each group were comparable on admission. All patients received intravenous quinine therapy. Four patients (21%) in each group died. There were no significant differences between the placebo- and dexamethasone-treated groups in time until patients became afebrile (median, 51 vs. 19 h), the level of consciousness became normal (mean, 80 vs. 83 h), or parasitemia was cleared (mean, 2.1 vs. 3.4 d) or in the incidence of complications. Coma or hyperparasitemia (greater than or equal to 5% of erythrocytes parasitized) at the time of admission and hypoglycemia at any time during hospitalization were significantly correlated with a fatal outcome, which was not improved by using dexamethasone. We conclude that high-dose dexamethasone is not indicated for treating cerebral malaria.

The pathology of lymphoreticular and genital tissues of silvered leaf monkeys (Presbytis cristata) experimentally infected with Wuchereria bancrofti.

The discovery of the silvered leaf monkey, Presbytis cristata, as a suitable experimental host for the human filarial parasite, Wuchereria bancrofti, opened the door for major advances in our understanding of the disease caused by this parasite. To study the pathogenesis of bancroftian filariasis in this model, 15 adult P. cristata which had been experimentally infected with 250 infective third-stage larvae of the parasite were examined. After inoculation with larvae, the monkeys were maintained under study for periods of 2 to 3 years, at which time all had achieved patent infections. At necropsy, Wuchereria-induced macroscopic lesions were not detected in experimentally infected monkeys. Microscopic findings included nematodiasis, microfilariasis, lymphadenitis, lymphangiectasis, perilymphangitis, splenitis, orchitis, periorchitis, epididymitis and funiculitis. Sections of normal adult worms were most often found in lymphatic vessels near lymph nodes, or in the lymphatics of the male genital system. These worms caused microfiliariasis in some regional lymph nodes. Inflammatory responses to filariae were most prominent in proximity to degenerated and dead worms, whereas intact, normal appearing adult worms elicited only minimal cellular response.

Pyrimethamine-sulfadoxine still effective against Plasmodium falciparum in Jayapura, Irian Jaya: RI-type resistance in 2 of 18 patients.

The sensitivity of Plasmodium falciparum infections to pyrimethamine-sulfadoxine was studied in 18 Indonesian patients in Jayapura, Irian Jaya. In 16 of the 18 patients parasitaemia was cleared by day 6 and the patients remained without parasitaemia through day 28. Two of the 18 patients had late recrudescences consistent with RI-type resistance; one each on days 14 and 21. Pyrimethamine-sulfadoxine is still an effective antimalarial for most patients with falciparum malaria in Jayapura.

Immunity to malaria and naturally acquired antibodies to the circumsporozoite protein of Plasmodium falciparum.

A candidate Plasmodium falciparum sporozoite vaccine, R32tet32, which includes 32 tetrapeptide repeats derived from the circumsporozoite protein of P. falciparum, has been developed on the basis of the hypothesis that antibodies to the repeat region of this protein will protect against sporozoite infection. The results of two in vitro assays, the circumsporozoite precipitation reaction and the inhibition of sporozoite invasion into hepatoma cells, are thought to indicate protective immunity. We therefore tested serum samples from persons living in a hyperendemic malarious area of Indonesia for antibodies against R32tet32 and for their ability to produce circumsporozoite precipitation and to inhibit sporozoite invasion of hepatoma cells. The prevalence and mean titer of antibody against R32tet32 increased with the age of the subjects, whereas the prevalence of P. falciparum infection in the community decreased. Only serum samples with IgG or IgM R32tet32 antibody titers greater than or equal to 1/800 had precipitation activity and invasion-inhibiting activity of more than 75 percent. When the serum samples were fractionated by affinity chromatography, only the fractions containing purified human antibody to R32tet32 were found to contain this activity. These data support the hypotheses that antibodies to the circumsporozoite protein are important in reducing the prevalence of malaria with increasing age among persons in areas in which malaria is endemic and that vaccine-elicited antibody to the circumsporozoite repeat region will protect against infection with P. falciparum sporozoites.

In vitro growth inhibition of Plasmodium falciparum by sera from tropical splenomegaly syndrome patients.

Sera from tropical splenomegaly syndrome (TSS) and non-TSS patients from the same village were examined for their ability to inhibit the in vitro growth of Plasmodium falciparum. Using synchronized malaria cultures, sera from both groups inhibited parasite development only if added before merozoite reinvasion of erythrocytes had occurred. There was no significant difference in the degree or apparent mechanism of inhibition caused by TSS and non-TSS sera. These results suggest that the aberrant immune response that results in TSS may not be associated with the elaboration of unique serum factors that differentially inhibit growth of the parasite in vitro.

Identification of Brugia malayi in vectors with a species-specific DNA probe.

We evaluated the potential value of a cloned sequence of genomic DNA of Brugia malayi as a species-specific probe. Clone pBm 15 reacted with all stages of 8 different geographic isolates of B. malayi and cross-hybridized with microfilariae of B. timori. It did not hybridize with Wuchereria bancrofti or with B. pahangi, W. kalimantani, Dirofilaria repens, Breinlia booliati or Cardiofilaria species, animal filariids that can be sympatric with B. malayi. P32-labeled clone pBm 15 correctly identified mosquitoes infected even with 1 infective larva of B. malayi. This specific DNA probe should be an invaluable tool to monitor control programs of Brugian filariasis.

RII and RIII type resistance of Plasmodium falciparum to combination of mefloquine and sulfadoxine/pyrimethamine in Indonesia.

2 of 36 Plasmodium falciparum infections were resistant (RII and RIII) in vivo to the combination of mefloquine (M) and sulfadoxine-pyrimethamine (SP) in Jayapura, Irian Jaya, Indonesia. Expected absorption of mefloquine and pyrimethamine was confirmed in the one resistant patient from whom sera were available, and the isolate from this patient was sensitive to mefloquine in vitro. Only 2 of 41 infections studied at the same time were resistant in vivo to SP. There was no clinical advantage of MSP compared with SP, and limited observations suggest there may be a disadvantage.

Evidence of possible natural infections of man with Brugia pahangi in South Kalimantan (Borneo), Indonesia.

Blood from 9 humans, 6 domestic cats (Felis domesticus), and 5 silvered leaf monkeys (Presbytis cristatus) from South Kalimantan (Borneo), Indonesia, with known filarial infections was examined for determination ofacid phosphatase activity of the microfilarae (mff). The findings suggest 1) that Brugia parasites from domestic cats and silvered leaf monkeys can be speciated by acid phosphatase activity and that speciation by acid phosphatase assay corresponds to that based upon adult worm morphology and 2) that Brugia mff from humans have acid phosphatase activity characteristic of that of B. pahangi microfilariae from cat and monkey. Thus B. pahangi may infect man in South Kalimantan.

The domestic cat as a host for Brugian filariasis in South Kalimantan (Borneo), Indonesia.

Three hundred and twenty-five domestic cats (Felis catus) from six villages of the Hulu Sungai Tengah and Banjar Regency of South Kalimantan (Borneo), Indonesia, were examined for filarial nematodes. Parasites were found in 66 cats, of which 61 (92.4%) had Brugia pahangi, four (6.1%) has B. malayi and one (1.5%) had Dirofilaria repens. Infection rates ranged from 11% to 22% in cats from secondary forest/rice-field habitats, from 15% to 30% in open village/rice-field habitats, to 50% in an open coastal village. In all cases the infection rate of B. malayi in man was greater than in cats from the same collecting area. The number of B. pahangi microfilariae per 20 microliter cat blood ranged from 34 at 1000 hours to 571 at 2200 hours. The results of this study suggest that in this region of Indonesia the domestic cat is not an important host for maintaining B. malayi.