Foliar chemistry and leaf herbivory on mount Bloomfield,Palawan, Philippines

Summary

Mount Bloomfield has a range of vegetation types on non-ultramafic and ultramafic soils. We report here foliar chemical analyses for N, P, K, Na, Ca, Mg, AI, B, Co, Cr, Cu, Fe, Mo, Mn, Ni, Si, Zn made on a large number of tree species. The most important results were: the notably high calcium in the ultramafic forest leaves, the occurrence of an aluminium accumulating species and two nickel accumulators on the ultramafic soils. Measurements of herbivory by the leaf-hole method showed that the percentage leaf area consumed by herbivores was similar in all the plots but the actual leaf area consumed was greater in the non-ultramafic forest because this had the largest leaves. There was no relationship between herbivory, and any of the leaf mineral elements investigated. Even the accumulating species were attacked by herbivores, of which the gall-formers and leaf-miners must be tolerant of high element concentrations, since the whole of their juvenile existence is in the leaf tissue.     

REDD Policy Impacts on Indigenous Property Rights Regimes on Palawan Island, the Philippines

Several Southeast Asian states have been working feverishly to design and implement REDD policy frameworks to fulfil their commitment to global climate change mitigation. In doing so, state agencies will be challenged to design REDD plus policies that value and conserve forest carbon in ways that align with national policies and local priorities for managing forest landscapes defined by complex property rights regimes. However, as with other market-based policies, the expeditious delivery of REDD could bypass critical analysis of potential interactions with national tenure regimes, customary property rights, and local livelihoods. Drawing on the case of Palawan Island—a forested frontier island in the Philippines—we examine how nascent REDD policies can articulate with state sanctioned tenure, customary tenure, and forest uses in changing livelihood contexts. This paper draws on research among Tagbanua and Pala’wan people to illustrate how complex and changing tenure structures, commodity markets and livelihood dynamics may influence how REDD plus interventions affect indigenous customary lands and forest use. We argue that the ability of indigenous forest users to maintain stored carbon and improve livelihoods is contingent upon the ‘socio-material’ form of carbon—a commodity defined in relation to the resources and social processes of which it is part.     

An extensive Cochlodinium bloom along the western coast of Palawan, Philippines

A massive fish kill and water discoloration were reported off the western coast of Puerto Princesa, Palawan, Philippines in March 2005. Phytoplankton analysis revealed a near monospecific bloom of the dinoflagellate, Cochlodinium polykrikoides, with cell concentrations ranging from 2.5 × 10⁵ to 3.2 × 10⁶ cells per liter. Ground truth data were supplemented by processed satellite images from MODIS Aqua Level 2 data (1 km resolution) from January to April 2005, which revealed high surface chlorophyll-a levels (up to 50 mg/m³) offshore of west and southwest Palawan as early as February 2005. The bloom extended 310 km in length and 80 km in width at its peak in March off the central coast (Puerto Princesa). By April, the bloom declined in intensity, but was still apparent along the northern coast (El Nido). Fluctuations in chlorophyll levels off the western coast of Sabah, Malaysia and Brunei during this time period suggested that the bloom was not limited to the coast of Palawan. Satellite imagery from Sabah in late January revealed a plume of chl-a that is believed to be the source of the C. polykrikoides bloom in Palawan. This plume drifted offshore, advected northward via the basin-wide counterclockwise gyre, and reached nutrient-rich, upwelled waters near Palawan (due to a positive wind stress curl) where the dinoflagellate bloomed and persisted for 2 months from March to April 2005.     

Allelic diversity in the merozoite surface protein 1 gene of Plasmodium falciparum on Palawan Island, the Philippines

Allelic diversity of the Plasmodium falciparum merozoite surface protein 1 gene (msp1) is mainly generated by meiotic recombination at the mosquito stage. We investigated recombination-based allelic diversity of msp1 in a P. falciparum population from Palawan Island, the Philippines, where malaria transmission is moderate. We identified the 5' recombinant types, 3' sequence types and msp1 haplotypes (unique combinations of 5' recombinant type and 3' sequence type), and compared them with those of P. falciparum from the Solomon Islands, where malaria transmission is high. The mean number of 5' recombinant types per patient in Palawan was 1.44, which is comparable to the number for the Solomon Islands (1.41). The Palawan parasite population had 15 msp1 haplotypes, whereas the Solomon Islands population had only 8 haplotypes. The Palawan population showed strong linkage disequilibrium between polymorphic blocks/sites within msp1, which is comparable to the results for the Solomon Islands. These findings support our hypothesis that the extent of allelic diversity of msp1 is determined not only by the transmission intensity but also by the number of msp1 alleles prevalent in the local parasite population and the extent of mixed-allele infections. Contribution of a high prevalence of the chloroquine (CQ)-sensitive allele of P. falciparum CQ resistance transporter (pfcrt) to the relatively high msp1 diversity in the Palawan population is discussed.     

Interrupting malaria transmission: quantifying the impact of interventions in regions of low to moderate transmission

Malaria has been eliminated from over 40 countries with an additional 39 currently planning for, or committed to, elimination. Information on the likely impact of available interventions, and the required time, is urgently needed to help plan resource allocation. Mathematical modelling has been used to investigate the impact of various interventions; the strength of the conclusions is boosted when several models with differing formulation produce similar data. Here we predict by using an individual-based stochastic simulation model of seasonal Plasmodium falciparum transmission that transmission can be interrupted and parasite reintroductions controlled in villages of 1,000 individuals where the entomological inoculation rate is <7 infectious bites per person per year using chemotherapy and bed net strategies. Above this transmission intensity bed nets and symptomatic treatment alone were not sufficient to interrupt transmission and control the importation of malaria for at least 150 days. Our model results suggest that 1) stochastic events impact the likelihood of successfully interrupting transmission with large variability in the times required, 2) the relative reduction in morbidity caused by the interventions were age-group specific, changing over time, and 3) the post-intervention changes in morbidity were larger than the corresponding impact on transmission. These results generally agree with the conclusions from previously published models. However the model also predicted changes in parasite population structure as a result of improved treatment of symptomatic individuals; the survival probability of introduced parasites reduced leading to an increase in the prevalence of sub-patent infections in semi-immune individuals. This novel finding requires further investigation in the field because, if confirmed, such a change would have a negative impact on attempts to eliminate the disease from areas of moderate transmission.     

Subsistence strategies of an indigenous minority in the Philippines: Nonwood forest product use by the Tagbanua of Narra, Palawan

Indigenous people, such as the Tagbanua of Palawan Island in the Philippines, are often considered to be experienced and responsible users of natural resources. The Tagbanua have traditionally been involved in the collection of nonwood forest products (NWFPs) both for trade and for subsistence purposes. The proximity of many Tagbanua communities to the forest allows them easy access to NWFPs, although various restrictions, such as distance from markets, legal land issues, and lack of formal education, prevent them from receiving more favorable earnings from the sale of NWFPs. Similarly, increasing access to manufactured products also lessens dependence on NWFPs for food, medicine, and housing purposes, although small incomes prevent extensive conversion to the use of purchased goods. The knowledge and current subsistence-level use of NWFPs by the Tagbanua from the settlement of Boong are described and discussed.     

The impact of two education methods on knowledge of schistosomiasis transmission and prevention among schoolchildren in a rural community in northern Minas Gerais, Brazil

The objective of this study was to analyse the effect of using two health education approaches on knowledge of transmission and prevention of schistosomiasis of school children living in a rural endemic area in the state of Minas Gerais, Brazil. The 87 children participating in the study were divided into three groups based on gender, age and presence or absence of Schistosoma mansoni infection. In the first group the social representation model and illness experience was used. In the second group, we used the cognitive model based on the transmission of information. The third group, the control group, did not receive any information related to schistosomiasis. Ten meetings were held with all three groups that received a pre-test prior to the beginning of the educational intervention and a post-test after the completion of the program. The results showed that knowledge levels in Group 1 increased significantly during the program in regard to transmission (p = 0.038) and prevention (p = 0.001) of schistosomiasis. Groups 2 and 3 did not show significant increase in knowledge between the two tests. These results indicate that health education models need to consider social representation and illness experience besides scientific knowledge in order to increase knowledge of schistosomiasis transmission and prevention.     

Linking community and disease ecology: the impact of biodiversity on pathogen transmission

The increasing number of zoonotic diseases spilling over from a range of wild animal species represents a particular concern for public health, especially in light of the current dramatic trend of biodiversity loss. To understand the ecology of these multi-host pathogens and their response to environmental degradation and species extinctions, it is necessary to develop a theoretical framework that takes into account realistic community assemblages. Here, we present a multi-host species epidemiological model that includes empirically determined patterns of diversity and composition derived from community ecology studies. We use this framework to study the interaction between wildlife diversity and directly transmitted pathogen dynamics. First, we demonstrate that variability in community composition does not affect significantly the intensity of pathogen transmission. We also show that the consequences of community diversity can differentially impact the prevalence of pathogens and the number of infectious individuals. Finally, we show that ecological interactions among host species have a weaker influence on pathogen circulation than inter-species transmission rates. We conclude that integration of a community perspective to study wildlife pathogens is crucial, especially in the context of understanding and predicting infectious disease emergence events.     

Patient Knowledge on Malaria Symptoms Is a Key to Promoting Universal Access of Patients to Effective Malaria Treatment in Palawan,the Philippines

Introduction

Palawan, where health care facilities are still limited, is one of the most malaria endemic provinces in the Philippines. Since 1999, microscopists (community health workers) have been trained in malaria diagnosis and feasibility of early diagnosis and treatments have been enhanced throughout the province. To accelerate the universal access of malaria patients to diagnostic testing in Palawan, positive health seeking behavior should be encouraged when malaria infection is suspected.

Methods

In this cross-sectional study, structured interviews were carried out with residents (N = 218) of 20 remote malaria-endemic villages throughout Palawan with a history of suspected malaria from January to February in 2012. Structural equation modeling (SEM) was conducted to determine factors associated with appropriate treatment, which included: (1) socio-demographic characteristics; (2) proximity to a health facility; (3) health seeking behavior; (4) knowledge on malaria; (5) participation in community awareness-raising activities.

Results

Three factors independently associated with appropriate treatment were identified by SEM (CMIN = 10.5, df = 11, CFI = 1.000, RMSEA = .000): “living near microscopist” (p < 0.001), “not living near private pharmacy” (p < 0.01), and “having severe symptoms” (p < 0.01). “Severe symptoms” were positively correlated with more “knowledge on malaria symptoms” (p < 0.001). This knowledge was significantly increased by attending “community awareness-raising activities by microscopists” (p < 0.001).

Conclusions

In the resource-limited settings, microscopists played a significant role in providing appropriate treatment to all participants with severe malaria symptoms. However, it was considered that knowledge on malaria symptoms made participants more aware of their symptoms, and further progressed self-triage. Strengthening this recognition sensitivity and making residents aware of nearby microscopists may be the keys to accelerating universal access to effective malaria treatment in Palawan.     

Simulated impact of RTS,S/AS01 vaccination programs in the context of changing malaria transmission

Introduction

The RTS,S/AS01 pre-erythrocytic malaria vaccine is in phase III clinical trials. It is critical to anticipate where and how it should be implemented if trials are successful. Such planning may be complicated by changing levels of malaria transmission.

Methods/results

Computer simulations were used to examine RTS,S/AS01 impact, using a vaccine profile based on phase II trial results, and assuming that protection decays only slowly. Settings were simulated in which baseline transmission (in the absence of vaccine) was fixed or varied between 2 and 20 infectious mosquito bites per person per annum (ibpa) over ten years. Four delivery strategies were studied: routine infant immunization (EPI), EPI plus infant catch-up, EPI plus school-based campaigns, and EPI plus mass campaigns. Impacts in changing transmission settings were similar to those in fixed settings. Assuming a persistent effect of vaccination, at 2 ibpa, the vaccine averted approximately 5–7 deaths per 1000 doses of vaccine when delivered via mass campaigns, but the benefit was less at higher transmission levels. EPI, catch-up and school-based strategies averted 2–3 deaths per 1000 doses in settings with 2 ibpa. In settings where transmission was decreasing or increasing, EPI, catch-up and school-based strategies averted approximately 3–4 deaths per 1000 doses.

Discussion

Where transmission is changing, it appears to be sufficient to consider simulations of pre-erythrocytic vaccine impact at a range of initial transmission levels. At 2 ibpa, mass campaigns averted the most deaths and reduced transmission, but this requires further study. If delivered via EPI, RTS,S/AS01 could avert approximately 6–11 deaths per 1000 vaccinees in all examined settings, similar to estimates for pneumococcal conjugate vaccine in African infants. These results support RTS,S/AS01 implementation via EPI, for example alongside vector control interventions, providing that the phase III trials provide support for our assumptions about efficacy.     

Fishing mortality rates of giant clams (Family Tridacnidae) from the Sulu Archipelago and Southern Palawan,Philippines

Average size frequency distributions of Tridacna squamosa, T. gigas, Hippopus hippopus and H. porcellanus harvested from the Sulu Archipelago and Southern Palawan areas from 1978–1985 were derived from export records and a warehouse inventory of giant clam shells. Average species mortality rates (Z) were estimated and were used to approximate average fishing mortality rates (F) over the period 1978–1985. Crude estimates of exploitation rates (F/Z) indicate that populations of these species are already overexploited. These findings have serious implications in view of the fact that the Sulu Archipelago and Southern Palawan are thought to be the last strongholds of giant clams in Philippine waters.     

Natural plant sugar sources of Anopheles mosquitoes strongly impact malaria transmission potential

An improved knowledge of mosquito life history could strengthen malaria vector control efforts that primarily focus on killing mosquitoes indoors using insecticide treated nets and indoor residual spraying. Natural sugar sources, usually floral nectars of plants, are a primary energy resource for adult mosquitoes but their role in regulating the dynamics of mosquito populations is unclear. To determine how the sugar availability impacts Anopheles sergentii populations, mark-release-recapture studies were conducted in two oases in Israel with either absence or presence of the local primary sugar source, flowering Acacia raddiana trees. Compared with population estimates from the sugar-rich oasis, An. sergentii in the sugar-poor oasis showed smaller population size (37,494 vs. 85,595), lower survival rates (0.72 vs. 0.93), and prolonged gonotrophic cycles (3.33 vs. 2.36 days). The estimated number of females older than the extrinsic incubation period of malaria (10 days) in the sugar rich site was 4 times greater than in the sugar poor site. Sugar feeding detected in mosquito guts in the sugar-rich site was significantly higher (73%) than in the sugar-poor site (48%). In contrast, plant tissue feeding (poor quality sugar source) in the sugar-rich habitat was much less (0.3%) than in the sugar-poor site (30%). More important, the estimated vectorial capacity, a standard measure of malaria transmission potential, was more than 250-fold higher in the sugar-rich oasis than that in the sugar-poor site. Our results convincingly show that the availability of sugar sources in the local environment is a major determinant regulating the dynamics of mosquito populations and their vector potential, suggesting that control interventions targeting sugar-feeding mosquitoes pose a promising tactic for combating transmission of malaria parasites and other pathogens.     

Modeling the dynamics and control of Schistosoma japonicum transmission on Bohol island, the Philippines

We have investigated a mathematical model for the transmission of Schistosoma japonicum in the infested region of northeastern Bohol island in the Philippines. The development of transmission models is important for planning control strategies. Since S. japonicum has a complicated mode of transmission, the rates of transmission among its hosts cannot be measured directly by field observation. Instead, they have been estimated through model analysis. The model takes into account the seasonal variations and includes a function of control measures. In 1981, a project to eliminate schistosomiasis started on Bohol island. The prevalence decreased dramatically and has kept low level less than 1%. The simulations based on the model predicted that there is little probability of resurgence of an epidemic in the northeastern endemic villages of Bohol island due to the fact that the project has attained a high coverage of selective mass treatment based on stool examination accompanied by a successful snail control operation.     

The freshwater crab fauna (Crustacea: Brachyura) of the Philippines. V. On a new genus and species of potamid from Palawan island, Philippines

A new genus and new species of terrestrial potamid crab ( Carpomon pomulum) is described from the island of Palawan in the Philippines. This new genus can easily be distinguished from all other Philippine potamids in its smooth and inflated carapace, no trace of an epibranchial tooth, extremely low postorbital cristae, and stout and twisted male first gonopod. This revised version was published online in July 2006 with corrections to the Cover Date.     

Integrated HIV testing, malaria, and diarrhea prevention campaign in Kenya: modeled health impact and cost-effectiveness

Background

Efficiently delivered interventions to reduce HIV, malaria, and diarrhea are essential to accelerating global health efforts. A 2008 community integrated prevention campaign in Western Province, Kenya, reached 47,000 individuals over 7 days, providing HIV testing and counseling, water filters, insecticide-treated bed nets, condoms, and for HIV-infected individuals cotrimoxazole prophylaxis and referral for ongoing care. We modeled the potential cost-effectiveness of a scaled-up integrated prevention campaign.

Methods

We estimated averted deaths and disability-adjusted life years (DALYs) based on published data on baseline mortality and morbidity and on the protective effect of interventions, including antiretroviral therapy. We incorporate a previously estimated scaled-up campaign cost. We used published costs of medical care to estimate savings from averted illness (for all three diseases) and the added costs of initiating treatment earlier in the course of HIV disease.

Results

Per 1000 participants, projected reductions in cases of diarrhea, malaria, and HIV infection avert an estimated 16.3 deaths, 359 DALYs and $85,113 in medical care costs. Earlier care for HIV-infected persons adds an estimated 82 DALYs averted (to a total of 442), at a cost of $37,097 (reducing total averted costs to $48,015). Accounting for the estimated campaign cost of $32,000, the campaign saves an estimated $16,015 per 1000 participants. In multivariate sensitivity analyses, 83% of simulations result in net savings, and 93% in a cost per DALY averted of less than $20.

Discussion

A mass, rapidly implemented campaign for HIV testing, safe water, and malaria control appears economically attractive.     

Using HIV transmission networks to investigate community effects in HIV prevention trials

Effective population screening of HIV and prevention of HIV transmission are only part of the global fight against AIDS. Community-level effects, for example those aimed at thwarting future transmission, are potential outcomes of treatment and may be important in stemming the epidemic. However, current clinical trial designs are incapable of detecting a reduction in future transmission due to treatment. We took advantage of the fact that HIV is an evolving pathogen whose transmission network can be reconstructed using genetic sequence information to address this shortcoming. Here, we use an HIV transmission network inferred from recently infected men who have sex with men (MSM) in San Diego, California. We developed and tested a network-based statistic for measuring treatment effects using simulated clinical trials on our inferred transmission network. We explored the statistical power of this network-based statistic against conventional efficacy measures and find that when future transmission is reduced, the potential for increased statistical power can be realized. Furthermore, our simulations demonstrate that the network statistic is able to detect community-level effects (e.g., reduction in onward transmission) of HIV treatment in a clinical trial setting. This study demonstrates the potential utility of a network-based statistical metric when investigating HIV treatment options as a method to reduce onward transmission in a clinical trial setting.     

Population dynamics and community structure of fish in the mangroves of Pagbilao, Philippines

128 fish species were recorded for the mangroves of Pagbilao. Aspects of the population dynamics of the common species, Ambassis kopsi, Secutor ruconius. Leiognathus brevirostris and Prosopodasys gogorzae were investigated. Growth coefficients varied from 0.41 to 1.2. Mortality in the mangroves was high, and most species there breed once per year.
Species diversity ( H ') of the community ranged from 1.05 to 2.9. It was influenced by evenness rather than by species richness. Species abundance gave a log normal distribution, except during the typhoon, when it fitted the niche preemption model.