Brugia Rapid™ antibody responses in communities of Indonesia in relation to the results of 'transmission assessment surveys' (TAS) for the lymphatic filariasis elimination program.

BACKGROUND: The Global Programme to Eliminate Lymphatic Filariasis recommends the transmission assessment survey (TAS) as the preferred methodology for determining whether mass drug administration can be stopped in an endemic area. Because of the limited experience available globally with the use of Brugia Rapid™ tests in conducting TAS in Brugia spp. areas, we explored the relationship between the antibody test results and Brugia spp. infection as detected by microfilaremia in different epidemiological settings. METHODS: The study analyzes the Brugia Rapid™ antibody responses and microfilaremia in all ages at three study sites in: i) a district which was classified as non-endemic, ii) a district which passed TAS, and iii) a district which failed TAS. Convenience sampling was done in each site, in one to three purposefully selected villages with a goal of 500 samples in each district. RESULTS: A total of 1543 samples were collected from residents in all three study sites. In the site which was classified as non-endemic and where MDA had not been conducted, 5 % of study participants were antibody positive, none was positive for microfilaremia, and age-specific antibody prevalence peaked at almost 8 % in the 25-34 year-old age range, with no antibody-positive results found in children under eight years of age. In the site that had passed TAS, 1 % of participants were antibody positive and none was positive for microfilaremia. In the site which failed TAS, 15 % of participants were antibody positive, 0.2 % were microfilaremic, and age-specific antibody prevalence was highest in 6-7 year olds (30 %), but above 8 % in all age levels above 8 years old. CONCLUSIONS: These results from districts which followed the current WHO guidance for mapping, MDA, and implementing TAS, while providing antibody profiles of treated and untreated populations under programmatic settings, support the choice of antibody prevalence in the 6- and 7-year-old age group in TAS for making stopping MDA decisions. Since only one study participant was microfilaremic, no conclusions could be drawn about the relationship between antibodies and microfilaremia and further longitudinal studies are required to understand this relationship.

Distribution of Plasmodium vivax pvdhfr and pvdhps alleles and their association with sulfadoxine-pyrimethamine treatment outcomes in Indonesia.

BACKGROUND: Sympatric existence of Plasmodium falciparum and Plasmodium vivax, and the practice of malaria treatment without microscopic confirmation suggest that the accidental treatment of vivax malaria with sulfadoxine-pyrimethamine (SP) is common. METHODS: In this study, the frequency distribution of alleles associated with SP resistance were analysed among the P. vivax infections from malariometric surveys and its association with SP treatment failure in clinical studies in Indonesia. The dhfr and dhps alleles were detected using PCR-RFLP method. RESULTS: Analysis of 159 P. vivax isolates from malariometric surveys and 69 samples from in vivo SP efficacy study revealed various the existence of various alleles of the pvdhfr and pfdhps genes including 57L/I, 58R, 61M, and 117N/T. Allele 13L of the dhfr gene and 553G of the dhps gene were not detected in any isolates examined in both studies. In the dhfr gene, tandem repeat type-A was the major tandem repeat observed in any isolates analysed. In the dhps gene, only the 383G allele was observed. Isolates carrying double, triple and quadruple mutants of dhfr gene were found in Lampung, Purworejo, Sumba, and Papua. Although this study revealed a wide distribution of dhfr and dhps alleles among the P. vivax isolates across a broad geographic regions in Indonesia, impact on SP efficacy was not observed in Sumba. CONCLUSION: With proper malaria diagnosis, SP may still be used as a rational anti-malarial drug either as a single prescription or in combination with artemisinin.

Seasonal distribution of anti-malarial drug resistance alleles on the island of Sumba, Indonesia.

BACKGROUND: Drug resistant malaria poses an increasing public health problem in Indonesia, especially eastern Indonesia, where malaria is highly endemic. Widespread chloroquine (CQ) resistance and increasing sulphadoxine-pyrimethamine (SP) resistance prompted Indonesia to adopt artemisinin-based combination therapy (ACT) as first-line therapy in 2004. To help develop a suitable malaria control programme in the district of West Sumba, the seasonal distribution of alleles known to be associated with resistance to CQ and SP among Plasmodium falciparum isolates from the region was investigated. METHODS: Plasmodium falciparum isolates were collected during malariometric surveys in the wet and dry seasons in 2007 using two-stage cluster sampling. Analysis of pfcrt, pfmdr1, pfmdr1 gene copy number, dhfr, and dhps genes were done using protocols described previously. RESULTS AND DISCUSSION: The 76T allele of the pfcrt gene is nearing fixation in this population. Pfmdr1 mutant alleles occurred in 72.8% and 53.3%, predominantly as 1042D and 86Y alleles that are mutually exclusive. The prevalence of amplified pfmdr1 was found 41.9% and 42.8% of isolates in the wet and dry seasons, respectively. The frequency of dhfr mutant alleles was much lower, either as a single 108N mutation or paired with 59R. The 437G allele was the only mutant dhps allele detected and it was only found during dry season. CONCLUSION: The findings demonstrate a slighly higher distribution of drug-resistant alleles during the wet season and support the policy of replacing CQ with ACT in this area, but suggest that SP might still be effective either alone or in combination with other anti-malarials.

Efficacy of artemisinin-based combination therapy for treatment of persons with uncomplicated Plasmodium falciparum malaria in West Sumba District, East Nusa Tenggara Province, Indonesia, and genotypic profiles of the parasite.

Reports on treatment failures associated with the use of first-and second-line antimalarial drugs chloroquine and sulfadoxine-pyrimethamine have recently increased in many parts of Indonesia. The present study evaluated artemisinin-based combination therapy for treatment of persons with uncomplicated Plasmodium falciparum malaria in West Sumba District, East Nusa Tenggara Province. A total of 103 persons 1-57 years of age were enrolled, given standard artesunate-amodiaquine therapy, and followed-up for 28 days. All persons clinically recovered, but two persons were again parasitemic on day 7. This finding indicated that these two persons had recurrent parasitemias on days 21 and 28. Molecular analyses suggested both recurrences were caused by reinfections. There were no severe adverse events, but complaints of gastrointestinal upset, nausea and vomiting, and headache linked to therapy occurred among 9.7%, 5.8% and 5.8% of the persons, respectively. Artesunate-amodiaquine proved efficacious therapy for treatment of persons with uncomplicated P. falciparum malaria at one site in eastern Indonesia but it may have tolerability problems that merit further investigation.

Seasonal prevalence of malaria in West Sumba district, Indonesia.

BACKGROUND: Accurate information about the burden of malaria infection at the district or provincial level is required both to plan and assess local malaria control efforts. Although many studies of malaria epidemiology, immunology, and drug resistance have been conducted at many sites in Indonesia, there is little published literature describing malaria prevalence at the district, provincial, or national level. METHODS: Two stage cluster sampling malaria prevalence surveys were conducted in the wet season and dry season across West Sumba, Nusa Tenggara Province, Indonesia. RESULTS: Eight thousand eight hundred seventy samples were collected from 45 sub-villages in the surveys. The overall prevalence of malaria infection in the West Sumba District was 6.83% (95% CI, 4.40, 9.26) in the wet season and 4.95% (95% CI, 3.01, 6.90) in the dry. In the wet season Plasmodium falciparum accounted for 70% of infections; in the dry season P. falciparum and Plasmodium vivax were present in equal proportion. Malaria prevalence varied substantially across the district; prevalences in individual sub-villages ranged from 0-34%. The greatest malaria prevalence was in children and teenagers; the geometric mean parasitaemia in infected individuals decreased with age. Malaria infection was clearly associated with decreased haemoglobin concentration in children under 10 years of age, but it is not clear whether this association is causal. CONCLUSION: Malaria is hypoendemic to mesoendemic in West Sumba, Indonesia. The age distribution of parasitaemia suggests that transmission has been stable enough to induce some clinical immunity. These prevalence data will aid the design of future malaria control efforts and will serve as a baseline against which the results of current and future control efforts can be assessed.

Malaria prevalence in Nias District, North Sumatra Province, Indonesia.

BACKGROUND: The Nias district of the North Sumatra Province of Indonesia has long been known to be endemic for malaria. Following the economic crisis at the end of 1998 and the subsequent tsunami and earthquake, in December 2004 and March 2005, respectively, the malaria control programme in the area deteriorated. The present study aims to provide baseline data for the establishment of a suitable malaria control programme in the area and to analyse the frequency distribution of drug resistance alleles associated with resistance to chloroquine and sulphadoxine-pyrimethamine. METHODS: Malariometric and entomology surveys were performed in three subdistricts. Thin and thick blood smears were stained with Giemsa and examined under binocular light microscopy. Blood blots on filter paper were also prepared for isolation of parasite and host DNA to be used for molecular analysis of band 3 (SAO), pfcrt, pfmdr1, dhfr, and dhps. In addition, haemoglobin measurement was performed in the second and third surveys for the subjects less than 10 years old. RESULTS: Results of the three surveys revealed an average slide positivity rate of 8.13%, with a relatively higher rate in certain foci. Host genetic analysis, to identify the Band 3 deletion associated with Southeast Asian Ovalocytosis (SAO), revealed an overall frequency of 1.0% among the 1,484 samples examined. One hundred six Plasmodium falciparum isolates from three sub-districts were successfully analysed. Alleles of the dhfr and dhps genes associated with resistance to sulphadoxine-pyrimethamine, dhfr C59R and S108N, and dhps A437G and K540E, were present at frequencies of 52.2%, 82.5%, 1.18% and 1.18%, respectively. The pfmdr1 alleles N86Y and N1042D, putatively associated with mefloquine resistance, were present at 31.4% and 2%, respectively. All but one sample carried the pfcrt 76T allele associated with chloroquine resistance. Entomologic surveys identified three potential anopheline vectors in the area, Anopheles barbirostris, Anopheles kochi and Anopheles sundaicus. CONCLUSION: The cross sectional surveys in three different sub-districts of Nias District clearly demonstrated the presence of relatively stable endemic foci of malaria in Nias District, North Sumatra Province, Indonesia. Molecular analysis of the malaria parasite isolates collected from this area strongly indicates resistance to chloroquine and a growing threat of resistance to sulphadoxine-pyrimethamine. This situation highlights the need to develop sustainable malaria control measures through regular surveillance and proper antimalarial drug deployment.