Efficacy of permethrin-impregnated bed nets on malaria control in a hyperendemic area in Irian Jaya, Indonesia III. Antibodies to circumsporozoite protein and ring-infected erythrocyte surface antigen.

A two years intervention study was carried out using permethrin impregnated bed nets in a hyperendemic area, in Irian Jaya, Indonesia. To assess the influence of this intervention on natural immunity, concurrent immunological studies to determine levels of antibodies to the circumsporozoite (CS) and ring-infected erythrocyte surface antigen (RESA) proteins were conducted. Prevalence and titers of immunoglobulins (Ig)G and IgG subclasses were periodically measured in 138 individuals (30 children under the age of ten and 108 villagers ten years old and older). In the younger group, seropositivity of total IgG against CS fluctuated according to the parasite infection rates; however, IgG seropositive reaction against RESA gradually increased. In the older age group, seropositivity of both kinds of antibodies was stable during the whole study period. Nevertheless, the geometric mean titers of total IgG against CS and RESA were significantly reduced in this latter group in individuals who contained these antibodies before and after intervention. The geometric mean titer of IgG3 subclass against RESA was decreased at a highly significant level (p = 0.0005), and that of IgG4 against the same antigen was also decreased although to a lesser extent (p = 0.02).

Efficacy of permethrin-impregnated bed nets on malaria control in a hyperendemic area in Irian Jaya, Indonesia: differentiation between two age groups.

A malaria intervention trial was conducted for two years to evaluate the efficacy of permethrin-impregnated bed nets in reducing malaria infection and splenomegaly in two different age groups, ie below and over age of ten, in a hyperendemic area in Irian Jaya, Indonesia. Permethrin-impregnated or placebo-treated bed nets were provided to a treated and a control village, respectively. Immediately after periods with moderate rainfall in the first year, treated bed nets decreased P. falciparum and P. vivax density in the blood of children <10 years (group 1) but did not reduce the percentage of infection with either species. Children >10 and adults (group 2) showed significant reduction only in P. falciparum infection rates and density, whereas P. vivax was not influenced. After an excessive rainfall season in the second year, the risk for P. falciparum infections in both age groups using treated nets was less than half of that in the control village. P. vivax infection rates were significantly lower in the treated village at the beginning of and after these heavy rainfalls. In the treated village, spleen enlargement was markedly reduced in the younger age group during the second year.

Efficacy of permethrin-impregnated bed nets on malaria control in a hyperendemic area in Irian Jaya, Indonesia: influence of seasonal rainfall fluctuations.

A malaria intervention study was carried out using permethrin impregnated bed nets in the south-central part of Irian Jaya with perennial transmission, from April 1993 to April 1995. Malariometric surveys were carried out periodically for parasite prevalence by species and for spleen rates. Prior to intervention, the percentage of Plasmodium falciparum infected inhabitants was significantly higher in Hiripau, where permethrin-impregnated bed nets were used during the study, than in the placebo-treated control village, Kaugapu. After two years of intervention the situation was reversed and figures higher in the control village (RR 0.19, 95% CI 0.10-0.36, p < 0.0001). Similarly, P. vivax infection rates, 12.4% in Hiripau vs 5.7% in Kaugapu in April 1993. were reversed in April 1995 (3.6% in Hiripau and 11.3% in Kaugapu, p < 0.001). In the treated village, pre-control hyperendemicity was reduced to a low mesoendemic level (spleen rate 12.5%) during two years of intervention, whereas the level was mesoendemic (spleen rate 35.2%) in the control village. Impregnated bed nets were found an effective intervention both in moderate (April 1993 through April 1994, 1,626 mm rainfall) and high (April 1994 through April 1995/1995, 3,321 mm) transmission seasons.

Malaria situation in several villages around Timika, south central Irian Jaya, Indonesia.

Malaria in Timika area, south central Irian Jaya, is a public health problem causing morbidity and mortality, particularly to the vulnerable age group. In August/September 1992 malariometric surveys were conducted simultaneously with sensitivity studies of Plasmodium falciparum to antimalarials, and bionomics of vectors in six villages around Timika (Mwapi, Kaugapu, Hiripau, Pomako, Mapurujaya, Kwamki Lama). The average overall spleen rate was 44.0%, the highest rate observed in Kwamki Lama (68.3%) and the lowest in Mapurujaya (13.7%). The average parasite rate in children aged 2-9 years was 60.6%. The highest rate was found in Mwapi (92.0%) and the lowest rate in Mapurujaya (4.8%). In the study area the dominant species was P. falciparum, (except in Kaugapu), followed by P. vivax. P. malariae and P. ovale were not observed. In vivo sensitivity studies done in 7 villages showed P. falciparum was resistant to chloroquine [51.3% S/R I (sensitive or 1st grade resistant), 43.6% R II and 5.1% R III] in Kwamki Lama, SP I and SP II (transmigrant settlements) and Timika health service center. In vitro sensitivity test in Kwamki Lama, SP I, SP II and Timika health service center showed 64.4% resistant to chloroquine, and remain sensitive to sulfadoxine-pyrimethamine, quinine and mefloquine. Vector studies revealed that Anophelese punctulatus and An. koliensis were the potential vectors as was confirmed by ELISA positive test with a sporozoite rate of 1.43% and 0.33% respectively. The vectors were indoor and outdoor resting.

Seroepidemiological studies of malaria in different endemic areas of Indonesia.

A total of 618 sera from inhabitants living in various endemic areas in Indonesia were examined for IgG against Plasmodium falciparum utilizing young trophozoites and mature schizonts as antigens by the method of ELISA and IFAT. In general, antibodies against trophozites (RESA) based on ELISA and antibodies against schizonts based on IFAT showed a correlation of malarial antibodies with the level of endemicity of the area examined. Anti-RESA antibody, detected either by ELISA or IFAT was more pronounced in the aparasitemic group compared to the parasitemic group. On the contrary, anti-schizont antibody measured by IFAT was more pronounced in the parasitemic group. Malarial antibody levels against the schizont-merozoite fraction of P. falciparum as assayed by ELISA appeared to develop more slowly compared to levels based on IFAT.

Decrease of malaria morbidity with community participation in central Java.

Malaria is still a problem in Java-Bali, although the Malaria Eradication Program started in the 1950's. In the First National Five Year Development Plan it was changed to the Malaria Control Program with the aim to reduce the morbidity and mortality rates through surveillance and spraying interventions using the primary health care approach. In 1984 in Central Java there were malaria areas with an average annual parasite incidence (API) between 1 and 7.5 promille covering about six million population, nearly one third of the population of Central Java. In this study an intervention alternative was carried out with weekly chloroquine prophylaxis to children below 10 years of age in 3 malaria areas of central Java, namely the villages Bedono Kluwung and Kalikutes in Purworejo Regency and Pablengan in Karang Anyar Regency. Health education about malaria with a learning module was conducted by key persons as an element of community participation. The activities of the key persons increased the ongoing surveillance. After one and a half years intervention (July 1985-February 1987) the spleen rates, parasite rates and fever cases dropped to nearly zero in the three study villages. From the results of this study it was recommended that in a malaria risk area with an API of more than 1 promille, intervention with collective chloroquine protection to children below 10 years of age could reduce the API to 1 promille or less. This intervention should be carried out if there is an increase of cases in the area to prevent small outbreaks.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro sensitivity of Plasmodium falciparum to chloroquine and other antimalarials in east Timor and east Kalimantan, Indonesia.

In Indonesia resistance of Plasmodium falciparum to chloroquine has spread to all provinces except Yogyakarta since the first report in 1974. The proportion of resistant cases is relatively low except in Irian Jaya and East Timor. The results of in vitro tests performed in East Timor showed 81.0% resistance to chloroquine, 87.5% to amodiaquine, 20.0% to sulfadoxine-pyrimethamine (S-P), 4.8% to mefloquine, and 100% sensitivity to quinine. The percentage of failures was between 11.1% and 71.4% and highest with the S-P combination. Multidrug resistance was observed in 9 cases (or 11.1%). The results of in vitro tests in East Kalimantan were: 62.8% resistance to chloroquine, 100% to amodiaquine, 85.7% to S-P combination, 3.2% to quinine, and 2.5% to mefloquine. Failures rates ranged between 21.2% and 37.1% the highest being with mefloquine. Multidrug resistance was more prominent and observed in 59 cases (84.3%) of which one case was resistant to 5 antimalarials, while 4 cases (5.7%) were resistant to chloroquine only, compared to 72 cases (88.9%) in East Timor.

The implementation of community participation in the control of malaria in rural Tanjung Pinang, Indonesia.

A study was undertaken to involve a hyperendemic community in Berakit village near Tanjung Pinang to participate actively in the control of malaria. Weekly chemoprophylaxis with chloroquine was given to all villagers of RK I with a population of about 700 for a period of one year. Nine cadres were selected from the community by the villagers for the distribution of the drug and coordinated by the head of the village. About 14-19 families were supervised by one cadre who was responsible for the weekly distribution of the drug to these families. The weekly dosage of the drug was adjusted according to age. The drug was taken in the presence of the cadres to assure the intake, and recorded by each cadre. The results showed that 93.7% of the villagers have taken the drug regularly. The remaining 6.3% of them showed refusal and irregular intake, or moved to another village during the period of prophylaxis. Although the drug has a bitter taste, most of the children were able to tolerate it. In general, mild side effects were reported and infrequently observed. Implementation of community participation to control malaria in this village showed good results which was reflected in the results of the malariometric surveys carried out before and after one year chemoprophylaxis. The spleen rate of about 600 villagers of RK I examined was 54.3% and the parasite rate 13.2% before the drug intervention. After one year chemoprophylaxis the spleen rate decreased to 21.7% and the parasite rate to 4.5% showing a significant difference.

Chloroquine resistant Plasmodium falciparum infection from Lampung and South Sumatra, Indonesia.

A report was made of 4 cases of chloroquine resistant Plasmodium falciparum infections. The infections, detected in Jakarta, were imported from Kotabumi, Tanjung Karang, the Island of Pidada in the Lampung Province and from Pangkalpinang on the Island Bangka in the Province of South Sumatra. Treatment with courses of 1500 mg chloroquine base and with increased dosages up to 2250 mg base failed to cure the patients. The chloroquine sensitivity test in vitro was carried out in 3 patients, which showed that the Plasmodium falciparum strains were resistant to chloroquine at the R I level. The strains appeared to be similar to the Malaya Camp strain. In vivo observations revealed that the parasites were resistant at the R I level with a delayed recrudescence. The chloroquine resistant falciparum malaria cases, acquired in South Sumatra, may therefore be regarded as the first reported cases from a focus outside the already known two foci in Indonesia, namely East Kalimantan and Irian Jaya. It may be expected that chloroquine resistant Plasmodium falciparum will be encountered in other parts of Indonesia in the near future. The use of a combination of sulfadoxine and pyrimethamine should not be recommended in Indonesia because chloroquine is still considered the drug of choice against all malaria infections in Indonesia.