Reduction in Acute Filariasis Morbidity during a Mass Drug Administration Trial to Eliminate Lymphatic Filariasis in Papua New Guinea

Background

Acute painful swelling of the extremities and scrotum are debilitating clinical manifestations of Wuchereria bancrofti infection. The ongoing global program to eliminate filariasis using mass drug administration is expected to decrease this and other forms of filarial morbidity in the future by preventing establishment of new infections as a consequence of eliminating transmission by the mosquito vector. We examined whether mass treatment with anti-filarial drugs has a more immediate health benefit by monitoring acute filariasis morbidity in Papua New Guinean communities that participated in a 5-year mass drug administration trial.

Methodology/Principal Findings

Weekly active surveillance for acute filariasis morbidity defined by painful swelling of the extremities, scrotum and breast was performed 1 year before and each year after 4 annual mass administrations of anti-filarial drugs (16,480 person-years of observation). Acute morbidity events lasted <3 weeks in 92% of affected individuals and primarily involved the leg (74–79% of all annual events). The incidence for all communities considered together decreased from 0.39 per person-year in the pre-treatment year to 0.31, 0.15, 0.19 and 0.20 after each of 4 annual treatments (p<0.0001). Residents of communities with high pre-treatment transmission intensities (224–742 infective bites/person/year) experienced a greater reduction in acute morbidity (0.62 episodes per person-year pre-treatment vs. 0.30 in the 4^th post-treatment year) than residents of communities with moderate pre-treatment transmission intensities (24–167 infective bites/person/year; 0.28 episodes per person-year pre-treatment vs. 0.16 in the 4^th post-treatment year).

Conclusions

Mass administration of anti-filarial drugs results in immediate health benefit by decreasing the incidence of acute attacks of leg and arm swelling in people with pre-existing infection. Reduction in acute filariasis morbidity parallels decreased transmission intensity, suggesting that continuing exposure to infective mosquitoes is involved in the pathogenesis of acute filariasis morbidity.     

Impact of Six Rounds of Mass Drug Administration on Brugian Filariasis and Soil-Transmitted Helminth Infections in Eastern Indonesia

Background

The lymphatic filarial parasite Brugia timori occurs only in eastern Indonesia where it causes high morbidity. The absence of an animal reservoir, the inefficient transmission by Anopheles mosquitoes and the high sensitivity to DEC/albendazole treatment make this species a prime candidate for elimination by mass drug administration (MDA).

Methodology/Principal Findings

We evaluated the effect of MDA using DEC and albendazole on B. timori and soil transmitted helminths (STH) in a cross-sectional study of a sentinel village on Alor Island annually over a period of 10 years. Pre-MDA the microfilaria (MF) prevalence was 26% and 80% of the residents had filaria-specific IgG4 antibodies. In 2010, 34 months after the 6^th round of MDA, MF and antibody rates were only 0.17% and 6.4%, respectively. The MDA campaign had also a beneficial effect on STH. Baseline prevalence rates for Ascaris, hookworm and Trichuris were 34%, 28%, and 11%, respectively; these rates were reduced to 27%, 4%, and 2% one year after the 5^th round of MDA. Unfortunately, STH rates rebounded 34 months after cessation of MDA and approached pre-MDA rates. However, the intensity of STH infection in 2009 was still reduced, and no heavy infections were detected.

Conclusions/Significance

MDA with DEC/albendazole has had a major impact on B. timori MF and IgG4 antibody rates, providing a proof of principle that elimination is feasible. We also documented the value of annual DEC/albendazole as a mass de-worming intervention and the importance of continuing some form of STH control after cessation of MDA for filariasis.     

Sequential Modelling of the Effects of Mass Drug Treatments on Anopheline-Mediated Lymphatic Filariasis Infection in Papua New Guinea

Background

Lymphatic filariasis (LF) has been targeted by the WHO for global eradication leading to the implementation of large scale intervention programs based on annual mass drug administrations (MDA) worldwide. Recent work has indicated that locality-specific bio-ecological complexities affecting parasite transmission may complicate the prediction of LF extinction endpoints, casting uncertainty on the achievement of this initiative. One source of difficulty is the limited quantity and quality of data used to parameterize models of parasite transmission, implying the important need to update initially-derived parameter values. Sequential analysis of longitudinal data following annual MDAs will also be important to gaining new understanding of the persistence dynamics of LF. Here, we apply a Bayesian statistical-dynamical modelling framework that enables assimilation of information in human infection data recorded from communities in Papua New Guinea that underwent annual MDAs, into our previously developed model of parasite transmission, in order to examine these questions in LF ecology and control.

Results

Biological parameters underlying transmission obtained by fitting the model to longitudinal data remained stable throughout the study period. This enabled us to reliably reconstruct the observed baseline data in each community. Endpoint estimates also showed little variation. However, the updating procedure showed a shift towards higher and less variable values for worm kill but not for any other drug-related parameters. An intriguing finding is that the stability in key biological parameters could be disrupted by a significant reduction in the vector biting rate prevailing in a locality.

Conclusions

Temporal invariance of biological parameters in the face of intervention perturbations indicates a robust adaptation of LF transmission to local ecological conditions. The results imply that understanding the mechanisms that underlie locally adapted transmission dynamics will be integral to identifying points of system fragility, and thus countermeasures to reliably facilitate LF extinction both locally and globally.     

Impact of Three Rounds of Mass Drug Administration on Lymphatic Filariasis in Areas Previously Treated for Onchocerciasis in Sierra Leone

Background

1974–2005 studies across Sierra Leone showed onchocerciasis endemicity in 12 of 14 health districts (HDs) and baseline studies 2005–2008 showed lymphatic filariasis (LF) endemicity in all 14 HDs. Three integrated annual mass drug administration (MDA) were conducted in the 12 co-endemic districts 2008–2010 with good geographic, programme and drug coverage. Midterm assessment was conducted 2011 to determine impact of these MDAs on LF in these districts.

Methodology/Principal Findings

The mf prevalence and intensity in the 12 districts were determined using the thick blood film method and results compared with baseline data from 2007–2008. Overall mf prevalence fell from 2.6% (95% CI: 2.3%–3.0%) to 0.3% (95% CI: 0.19%–0.47%), a decrease of 88.5% (p = 0.000); prevalence was 0.0% (100.0% decrease) in four districts: Bo, Moyamba, Kenema and Kono (p = 0.001, 0.025, 0.085 and 0.000 respectively); and seven districts had reductions in mf prevalence of between 70.0% and 95.0% (p = 0.000, 0.060, 0.001, 0.014, 0.000, 0.000 and 0.002 for Bombali, Bonthe, Kailahun, Kambia, Koinadugu, Port Loko and Tonkolili districts respectively). Pujehun had baseline mf prevalence of 0.0%, which was maintained. Only Bombali still had an mf prevalence ≥1.0% (1.58%, 95% CI: 0.80%–3.09%)), and this is the district that had the highest baseline mf prevalence: 6.9% (95% CI: 5.3%–8.8%). Overall arithmetic mean mf density after three MDAs was 17.59 mf/ml (95% CI: 15.64 mf/ml–19.55 mf/ml) among mf positive individuals (65.4% decrease from baseline of 50.9 mf/ml (95% CI: 40.25 mf/ml–61.62 mf/ml; p = 0.001) and 0.05 mf/ml (95% CI: 0.03 mf/ml–0.08 mf/ml) for the entire population examined (96.2% decrease from baseline of 1.32 mf/ml (95% CI: 1.00 mf/ml–1.65 mf/ml; p = 0.000)).

Conclusions/Significance

The results show that mf prevalence decreased to <1.0% in all but one of the 12 districts after three MDAs. Overall mf density reduced by 65.0% among mf-positive individuals, and 95.8% for the entire population.     

Epidemiological Assessment of Eight Rounds of Mass Drug Administration for Lymphatic Filariasis in India: Implications for Monitoring and Evaluation

Background

Monitoring and evaluation guidelines of the programme to eliminate lymphatic filariasis require impact assessments in at least one sentinel and one spot-check site in each implementation unit (IU). Transmission assessment surveys (TAS) that assess antigenaemia (Ag) in children in IUs that have completed at least five rounds of mass drug administration (MDA) each with >65% coverage and with microfilaria (Mf) levels <1% in the monitored sites form the basis for stopping the MDA. Despite its rigour, this multi-step process is likely to miss sites with transmission potential (‘hotspots’) and its statistical assumptions for sampling and threshold levels for decision-making have not been validated. We addressed these issues in a large-scale epidemiological study in two primary health centres in Thanjavur district, India, endemic for bancroftian filariasis that had undergone eight rounds of MDA.

Methodology/Principal Findings

The prevalence and intensity of Mf (per 60 µl blood) were 0.2% and 0.004 respectively in the survey that covered >70% of 50,363 population. The corresponding values for Ag were 2.3% and 17.3 Ag-units respectively. Ag-prevalence ranged from 0.7 to 0.9%, in children (2–10 years) and 2.7 to 3.0% in adults. Although the Mf-levels in the survey and the sentinel/spot check sites were <1% and Ag-level was <2% in children, we identified 7 “residual” (Mf-prevalence ≥1%, irrespective of Ag-status in children) and 17 “transmission” (at least one Ag-positive child born during the MDA period) hotspots. Antigenaemic persons were clustered both at household and site levels. We identified an Ag-prevalence of ∼1% in children (equivalent to 0.4% community Mf-prevalence) as a possible threshold value for stopping MDA.

Conclusions/Significance

Existence of ‘hotspots’ and spatial clustering of infections in the study area indicate the need for developing good surveillance strategies for detecting ‘hotspots’, adopting evidence-based sampling strategies and evaluation unit size for TAS.     

Modeling the Impact and Costs of Semiannual Mass Drug Administration for Accelerated Elimination of Lymphatic Filariasis

The Global Program to Eliminate Lymphatic Filariasis (LF) has a target date of 2020. This program is progressing well in many countries. However, progress has been slow in some countries, and others have not yet started their mass drug administration (MDA) programs. Acceleration is needed. We studied how increasing MDA frequency from once to twice per year would affect program duration and costs by using computer simulation modeling and cost projections. We used the LYMFASIM simulation model to estimate how many annual or semiannual MDA rounds would be required to eliminate LF for Indian and West African scenarios with varied pre-control endemicity and coverage levels. Results were used to estimate total program costs assuming a target population of 100,000 eligibles, a 3% discount rate, and not counting the costs of donated drugs. A sensitivity analysis was done to investigate the robustness of these results with varied assumptions for key parameters. Model predictions suggested that semiannual MDA will require the same number of MDA rounds to achieve LF elimination as annual MDA in most scenarios. Thus semiannual MDA programs should achieve this goal in half of the time required for annual programs. Due to efficiency gains, total program costs for semiannual MDA programs are projected to be lower than those for annual MDA programs in most scenarios. A sensitivity analysis showed that this conclusion is robust. Semiannual MDA is likely to shorten the time and lower the cost required for LF elimination in countries where it can be implemented. This strategy may improve prospects for global elimination of LF by the target year 2020.     

The Role of Personal Opinions and Experiences in Compliance with Mass Drug Administration for Lymphatic Filariasis Elimination in Kenya

Background

The main strategy adopted for Lymphatic Filariasis (LF) elimination globally is annual mass drug administration (MDA) for 4 to 6 rounds. At least 65% of the population at risk should be treated in each round for LF elimination to occur. In Kenya, MDA using diethylcarbamazine citrate (DEC) and albendazole data shows declining compliance (proportion of eligible populations who receive and swallow the drugs) levels (85%–62.8%). The present study''s aim was to determine the role of personal opinions and experiences in compliance with MDA.

Methods/Findings

This was a retrospective cross-sectional study conducted between January and September 2009 in two districts based on December 2008 MDA round. In each district, one location with high and one with low compliance was selected. Through systematic sampling, nine villages were selected and interviewer-based questionnaires administered to 965 household heads or adult representatives also systematically sampled. The qualitative data were generated from opinion leaders, LF patients with clinical signs and community drug distributors (CDDs) all purposively selected and interviewed. Sixteen focus group discussions (FGDs) were also conducted with single-sex adult and youth male and female groups. Chi square test was used to assess the statistical significance of differences in compliance with treatment based on the records reviewed.The house-to-house method of drug distribution influenced compliance. Over one-quarter (27%) in low compared to 15% in high compliance villages disliked this method. Problems related to size, number and taste of the drugs were more common in low (16.4%) than in high (14.4%) compliance villages. Reasons for failure to take the drugs were associated with compliance (p<0.001). The reasons given included: feeling that the drugs were not necessary, CDD not visiting to issue the drugs, being absent and thinking that the drugs were meant for only the patients with LF clinical signs. A dislike for modern medicine prevailed more in low (6.7%) than in high (1.2%) compliance villages. Experience of side effects influenced compliance (P<0.001). The common side effects experienced included giddiness, fever, headache and vomiting. Social support, alcohol and substance use were not associated with compliance in both types of villages (p>0.05).

Conclusions/Significance

Community sensitization on treatment, drugs used, their regimen and distribution method involving all leaders should be strengthened by the Programme Implementers. The communities need to be made aware of the potential side effects of the drugs and that health personnel are on standby for the management of side effects in order to build confidence and increase the compliance levels.     

Long-Lasting Insecticidal Nets Are Synergistic with Mass Drug Administration for Interruption of Lymphatic Filariasis Transmission in Nigeria

In central Nigeria Anopheles mosquitoes transmit malaria and lymphatic filariasis (LF). The strategy used for interrupting LF transmission in this area is annual mass drug administration (MDA) with albendazole and ivermectin, but after 8 years of MDA, entomological evaluations in sentinel villages showed continued low-grade mosquito infection rates of 0.32%. After long-lasting insecticidal net (LLIN) distribution by the national malaria program in late 2010, however, we were no longer able to detect infected vectors over a 24-month period. This is evidence that LLINs are synergistic with MDA in interrupting LF transmission.     

The epidemiology of malaria in Papua New Guinea

Papua New Guinea (PNG) is a patchwork of different ecological zones, inhabited by human populations of exceptional cultural and linguistic diversity. This results in complex variations in vector ecology and malaria epidemiology. Malaria is the main cause of morbidity in many health facilities in lowland areas, but it is absent in much of the highlands. All four human malaria species occur, but endemicity varies widely, with Plasmodium falciparum locally reaching holo-endemic levels that are rarely found outside sub-Saharan Africa. The high frequency of Plasmodium vivax is an important difference to most African situations. PNG is therefore a prime location for studies of interactions between different parasite species, and of the biology of local human genetic adaptation and its implications for malaria morbidity and mortality.     

Reflecting on Loss in Papua New Guinea

This article takes up the conundrum of conducting anthropological fieldwork with people who claim that they have ‘lost their culture,’ as is the case with Suau people in the Massim region of Papua New Guinea. But rather than claiming culture loss as a process of dispossession, Suau claim it as a consequence of their own attempts to engage with colonial interests. Suau appear to have responded to missionization and their close proximity to the colonial-era capital by jettisoning many of the practices characteristic of Massim societies, now identified as ‘kastom.’ The rejection of kastom in order to facilitate their relations with Europeans during colonialism, followed by the mourning for kastom after independence, both invite consideration of a kind of reflexivity that requires action based on the presumed perspective of another.     

Mass treatment with ivermectin for filariasis control in Papua New Guinea: impact on mosquito survival

Field studies were carried out to determine the impact of mass human treatment with ivermectin on the survival of anthropophagic mosquitoes of the Anopheles punctulatus complex (Diptera: Culicidae), the vectors of lymphatic filariasis and malaria in Papua New Guinea. In a village where mass treatment had been given, using 400 microg/kg ivermectin plus 6 mg/kg diethylcarbamazine citrate (DEC), we performed pre- and post-treatment collections of freshly blood-engorged mosquitoes from the same nine bedrooms. All blood-fed mosquitoes collected less than 4 days after mass treatment died within 9 days, whereas 67% of those collected before treatment survived for >9 days. Comparison (using the log-rank test) of the survival curves for mosquitoes collected (i) before treatment, (ii)<4 days after treatment, and (iii) 28 days after treatment, showed the survival rate of group (ii) to be significantly lower than the other two (chi2=176, df=2, P<0.0001). Pre- and post-treatment all-night landing catches showed no reduction in human biting rates in the experimental village. In another village, where people were mass treated with ivermectin (400 microg/kg) only, the survival rates of freshly blood-engorged An. punctulatus collected from bedroom resting-sites less than 1 day after treatment, were compared to similar collections carried out at the same time in a nearby village where people were not treated with ivermectin. The 48-h survival rate for the ivermectin-treated village was 31% compared to 94% for the other; this difference was highly significant (chi2=32.42, df=1, P<0.0001). Mosquitoes fed 2 months post-treatment with DEC or collected 38 days post-treatment with ivermectin had normal survival rates. We conclude that the duration of the systemic lethal effect of ivermectin on mosquitoes is insufficient to be of epidemiological significance in filariasis control programmes that are based on biannual and annual single-dose treatments, but might reduce vectorial capacity sufficiently to block epidemics of dengue or even malaria.     

Drug resistance-conferring mutations in Mycobacterium tuberculosis from Madang, Papua New Guinea

ABSTRACT: BACKGROUND: Monitoring drug resistance in Mycobacterium tuberculosis is essential to curb the spread of tuberculosis (TB). Unfortunately, drug susceptibility testing is currently not available in Papua New Guinea (PNG) and that impairs TB control in this country. We report for the first time M. tuberculosis mutations associated with resistance to first and second-line anti-TB drugs in Madang, PNG. A molecular cluster analysis was performed to identify M. tuberculosis transmission in that region. RESULTS: Phenotypic drug susceptibility tests showed 15.7% resistance to at least one drug and 5.2% multidrug resistant (MDR) TB. Rifampicin resistant strains had the rpoB mutations D516F, D516Y or S531L; isoniazid resistant strains had the mutations katG S315T or inhA promoter C15T; streptomycin resistant strains had the mutations rpsL K43R, K88Q, K88R), rrs A514C or gidB V77G. The molecular cluster analysis indicated evidence for transmission of resistant strain. CONCLUSIONS: We observed a substantial rate of MDR-TB in the Madang area of PNG associated with mutations in specific genes. A close monitoring of drug resistance is therefore urgently required, particularly in the presence of drug-resistant M. tuberculosis transmission. In the absence of phenotypic drug susceptibility testing in PNG, molecular assays for drug resistance monitoring would be of advantage.     

Molecular Xenomonitoring Using Mosquitoes to Map Lymphatic Filariasis after Mass Drug Administration in American Samoa

Background

Mass drug administration (MDA) programs have dramatically reduced lymphatic filariasis (LF) incidence in many areas around the globe, including American Samoa. As infection rates decline and MDA programs end, efficient and sensitive methods for detecting infections are needed to monitor for recrudescence. Molecular methods, collectively termed ‘molecular xenomonitoring,’ can identify parasite DNA or RNA in human blood-feeding mosquitoes. We tested mosquitoes trapped throughout the inhabited islands of American Samoa to identify areas of possible continuing LF transmission after completion of MDA.

Methodology/Principle Findings

Mosquitoes were collected using BG Sentinel traps from most of the villages on American Samoa''s largest island, Tutuila, and all major villages on the smaller islands of Aunu''u, Ofu, Olosega, and Ta''u. Real-time PCR was used to detect Wuchereria bancrofti DNA in pools of ≤20 mosquitoes, and PoolScreen software was used to infer territory-wide prevalences of W. bancrofti DNA in the mosquitoes. Wuchereria bancrofti DNA was found in mosquitoes from 16 out of the 27 village areas sampled on Tutuila and Aunu''u islands but none of the five villages on the Manu''a islands of Ofu, Olosega, and Ta''u. The overall 95% confidence interval estimate for W. bancrofti DNA prevalence in the LF vector Ae. polynesiensis was 0.20–0.39%, and parasite DNA was also detected in pools of Culex quinquefasciatus, Aedes aegypti, and Aedes (Finlaya) spp.

Conclusions/Significance

Our results suggest low but widespread prevalence of LF on Tutuila and Aunu''u where 98% of the population resides, but not Ofu, Olosega, and Ta''u islands. Molecular xenomonitoring can help identify areas of possible LF transmission, but its use in the LF elimination program in American Samoa is limited by the need for more efficient mosquito collection methods and a better understanding of the relationship between prevalence of W. bancrofti DNA in mosquitoes and infection and transmission rates in humans.     

Increasing Compliance with Mass Drug Administration Programs for Lymphatic Filariasis in India through Education and Lymphedema Management Programs

Background

Nearly 45% of people living at risk for lymphatic filariasis (LF) worldwide live in India. India has faced challenges obtaining the needed levels of compliance with its mass drug administration (MDA) program to interrupt LF transmission, which utilizes diethylcarbamazine (DEC) or DEC plus albendazole. Previously identified predictors of and barriers to compliance with the MDA program were used to refine a pre-MDA educational campaign. The objectives of this study were to assess the impact of these refinements and of a lymphedema morbidity management program on MDA compliance.

Methods/Principal Findings

A randomized, 30-cluster survey was performed in each of 3 areas: the community-based pre-MDA education plus community-based lymphedema management education (Com-MDA+LM) area, the community-based pre-MDA education (Com-MDA) area, and the Indian standard pre-MDA education (MDA-only) area. Compliance with the MDA program was 90.2% in Com-MDA+LM, 75.0% in Com-MDA, and 52.9% in the MDA-only areas (p<0.0001). Identified barriers to adherence included: 1) fear of side effects and 2) lack of recognition of one''s personal benefit from adherence. Multivariable predictors of adherence amenable to educational intervention were: 1) knowing about the MDA in advance of its occurrence, 2) knowing everyone is at risk for LF, 3) knowing that the MDA was for LF, and 4) knowing at least one component of the lymphedema management techniques taught in the lymphedema management program.

Conclusions/Significance

This study confirmed previously identified predictors of and barriers to compliance with India''s MDA program for LF. More importantly, it showed that targeting these predictors and barriers in a timely and clear pre-MDA educational campaign can increase compliance with MDA programs, and it demonstrated, for the first time, that lymphedema management programs may also increase compliance with MDA programs.     

The trans-national gold curse of Papua New Guinea

This paper reviews gold and copper mining in Papua New Guinea (PNG) along the “triad stakeholder model” (Ballard and Banks 2003) proposing a triad relationship between (1) trans-national mining corporations, (2) the nation-state of Papua New Guinea, and (3) indigenous local communities, their socio-ecological environment and claims. Gold mining could be a huge asset, but turns out to be a curse to the independent part of the world’s second largest island known as “a mountain of gold in a sea of oil.” Our paper is based on research that began during our year-long residency at the country’s only Technical University in Lae. We are discussing several issues related to the nation’s gold resources and their exploitation: varied mining technologies and locations, the environmental impact, economics, human cost and gender issues, indigenous culture versus international corporate culture, state interferences, and urban development. One example is the industrial port city of Lae, founded during the gold rush of the 1920s that inaugurated rapid urban development. Once gloriously known as the “Pearl of the Pacific,” the town experienced administrative expansion and suffered from the subsequent exhaustion of nearby gold mines entailing a reverse development.     

A Comprehensive Assessment of Lymphatic Filariasis in Sri Lanka Six Years after Cessation of Mass Drug Administration

BackgroundThe Sri Lankan Anti-Filariasis Campaign conducted 5 rounds of mass drug administration (MDA) with diethycarbamazine plus albendazole between 2002 and 2006. We now report results of a comprehensive surveillance program that assessed the lymphatic filariasis (LF) situation in Sri Lanka 6 years after cessation of MDA.ConclusionsComprehensive surveillance is feasible for some national filariasis elimination programs. Low-level persistence of LF was present in all study sites; several sites failed to meet provisional endpoint criteria for LF elimination, and follow-up testing will be needed in these areas. TAS was not sensitive for detecting low-level persistence of filariasis in Sri Lanka. We recommend use of antibody and MX testing as tools to complement TAS for post-MDA surveillance.     

Review. Reflections on amyloidosis in Papua New Guinea

The amyloidoses comprise a heterogeneous group of diseases in which 1 out of more than 25 human proteins aggregates into characteristic beta-sheet fibrils with some unique properties. Aggregation is nucleation dependent. Among the known amyloid-forming constituents is the prion protein, well known for its ability to transmit misfolding and disease from one individual to another. There is increasing evidence that other amyloid forms also may be transmissible but only if certain prerequisites are fulfilled. One of these forms is systemic AA-amyloidosis in which an acute-phase reactant, serum AA, is over-expressed and, possibly after cleavage, aggregates into amyloid fibrils, causing disease. In a mouse model, this disorder can easily be transmitted from one animal to another both by intravenous and oral routes. Also, synthetic amyloid-like fibrils made from defined small peptides have this property, indicating a prion-like transmission mechanism. Even some fibrils occurring in the environment can transmit AA-amyloidosis in the murine model. AA-amyloidosis is particularly common in certain areas of Papua New Guinea, probably due to the endemicity of malaria and perhaps genetic predisposition. Now, when kuru is disappearing, more interest should be focused on the potentially lethal systemic AA-amyloidosis.     

Mapping forest-cover disturbances in Papua New Guinea with AVHRR data

Abstract. Land management and land-use planning in a forested country such as Papua New Guinea, which is subject to various anthropogenic pressures, requires an accurate mapping of forest-cover disturbances. The central hypothesis of this study was that remote sensing indicators of forest-cover conditions can be used to measure and map the impact of long-term forest-cover disturbances. This was tested with single year NOAA's Advanced Very-High Resolution Radiometer sensor (AVHRR) data at 1.1 km resolution. First, an ordinal scale of forest-cover disturbance was defined from field observations, a set of thematic maps and high spatial resolution satellite sensor data. Secondly, we analysed the relationship between the forest-cover disturbance scale and several biophysical indicators derived from AVHRR data at two seasons. Thirdly, a statistical analysis identified the optimal combination of biophysical indicators and observation dates to discriminate between the forest disturbance levels defined previously. A forest-cover disturbance map was then produced over part of Papua New Guinea. Finally, a regionalization of the study area in terms of aggregate degree of disturbance was produced and the spatial patterns of forest disturbances were interpreted for each region in terms of broad processes of forest-cover change. The overall accuracy of the forest-cover disturbance map was 79%. Nine regions, homogeneous in regard to the distribution and spatial pattern of disturbance categories, were identified.     

Molecular parasitology of malaria in Papua New Guinea

Research into the molecular biology of infectious diseases is mostly associated with well-developed countries. But in the midst of tropical Papua New Guinea, highly sophisticated molecular research has being conducted over years to understand and fight malaria and other tropical diseases. Here, we review such research carried out at the Papua New Guinea Institute of Medical Research. This Institute has considerably shaped research on molecular epidemiology through its analysis of the diversity and structure of the Plasmodium falciparum population. In addition, research has been conducted on human host factors and, more recently, the molecular analysis of drug resistance and the underlying molecular mechanisms of host-parasite interactions have been investigated.