Health and environmental impact of agricultural intensification: Translating Ecohealth program-derived knowledge into practice

International Development Research Centr

Ecohealth research to regionally address agriculture intensification impacts on health and the environment in Southeast Asia and China

Ecohealth Field Building Leadership Initiative is a regional operational research network in Southeast Asia and China that focuses on solving human health problems associated with agricultural intensification. FBLI has 3 focus areas, namely research, capacity building and knowledge translation. FBLI gathers researchers, policy makers, community members and other stakeholders from 4 focused countries (China, Indonesia, Thailand and Vietnam). Here we describe the operational research component that focuses on aspects of agriculture intensification on health and the environment including animal waste from pig production (Vietnam), dairy production (Indonesia), pesticide use in vegetable production (China), and health risks in rubber plantation (Thailand). Integrated approaches to the research component including survey, participatory and cross-cutting methods are discussed. The research results from Vietnam and Indonesia showed health and environmental impacts of manure management options, in particular the biogas system and turning waste to value. In Hanam of Vietnam, the health risks from biogas effluent reuse include E. coli infection (19–22% of population exposed) and G. lamblia infection (45–55% of population exposed). In Pangalengan, Indonesia, the Ecohealth approach was used to promote the production of medicinal worm and casting biofertilizer from cow manure as an environmentallyfriendly fertilizer alternative. In Chachoengsao Province of Thailand, key findings include evidences for higher risk of vectorborne diseases (dengue and chikungunya) in rubber plantation areas as well as higher microbial and heavy metal contamination of water and soil. In six villages of three townships in a County of Yunnan Province, China, issues identified were lack of farmer knowledge of pesticides, pesticide abuse, and ineffective policy to reduce pesticide abuse. Pesticide contamination was recorded from 6.1% to 12.7% of vegetables depending on sampling location in the field or market. The findings from 4 countries illustrate how Ecohealth research has been applied in health and agriculture and serve as basis for interventions for reduce health and environmental risks

Poultry farm vulnerability and risk of avian influenza re-emergence in Thailand

Highly pathogenic avian influenza (HPAI) remains of concern as a major potential global threat. This article evaluates and discusses the level of vulnerability of medium and small-scale commercial poultry production systems in Thailand related to avian influenza virus re-emergence. We developed a survey on 173 farms in Nakhon Pathom province to identify the global level of vulnerability of farms, and to determine which type of farms appears to be more vulnerable. We used official regulations (the Good Agricultural Practices and Livestock Farm Standards regulations) as a reference to check whether these regulations are respected. The results show that numerous vulnerability factors subsist and could represent, in case of HPAI re-emergence, a significant risk for a large spread of the disease. Bio-security, farm management and agro-commercial practices are particularly significant on that matter: results show that these practices still need a thorough improvement on a majority of farms. Farms producing eggs (especially duck eggs) are more vulnerable than farms producing meat. Those results are consistent with the type of farms that were mostly affected during the 2004–2008 outbreaks in Thailand

Field Building Leadership Initiative (FBLI): Advancing ecohealth in Southeast Asia

In response to global environmental health challenges, multi-disciplinary research and training are becoming popular among several countries in the world. However, systemic degree training programmes emphasizing integration of multi-disciplines are still not existed in the Asian Region. With approval from the University Council of Mahidol University, the Degree Programmes in "One Health and Ecosystem Management" are currently under development in collaboration with the University of Indonesia, Kunming Medical University and Hanoi School of Public Health. This will be one big step in integrating One Health/Ecohealth concept and system thinking into university curricula. The main objective is to produce high quality and competent graduates, who have background in multi-disciplinary research aiming at healthy environment and healthy living, to work in either government or private sectors. The research-based topics will be emphasized on an application of One Health/Ecohealth approach to human and animal health, environmental health, emerging and re-emerging infectious diseases, and social science, economics and policy in One Health/Ecohealth. It is expected that the students resulting from these programmes should help bringing One Health/Ecohealth practice into their professional work which hopefully will improve disease management and, hence, improve well-being in the long-term

Evaluation of alternative mosquito sampling methods for malaria vectors in Lowland South - East Zambia.

Sampling malaria vectors and measuring their biting density is of paramount importance for entomological surveys of malaria transmission. Human landing catch (HLC) has been traditionally regarded as a gold standard method for surveying human exposure to mosquito bites. However, due to the risk of human participant exposure to mosquito-borne parasites and viruses, a variety of alternative, exposure-free trapping methods were compared in lowland, south-east Zambia. Centres for Disease Control and Prevention miniature light trap (CDC-LT), Ifakara Tent Trap model C (ITT-C), resting boxes (RB) and window exit traps (WET) were all compared with HLC using a 3 × 3 Latin Squares design replicated in 4 blocks of 3 houses with long lasting insecticidal nets, half of which were also sprayed with a residual deltamethrin formulation, which was repeated for 10 rounds of 3 nights of rotation each during both the dry and wet seasons. The mean catches of HLC indoor, HLC outdoor, CDC-LT, ITT-C, WET, RB indoor and RB outdoor, were 1.687, 1.004, 3.267, 0.088, 0.004, 0.000 and 0.008 for Anopheles quadriannulatus Theobald respectively, and 7.287, 6.784, 10.958, 5.875, 0.296, 0.158 and 0.458, for An. funestus Giles, respectively. Indoor CDC-LT was more efficient in sampling An. quadriannulatus and An. funestus than HLC indoor (Relative rate [95% Confidence Interval] = 1.873 [1.653, 2.122] and 1.532 [1.441, 1.628], respectively, P < 0.001 for both). ITT-C was the only other alternative which had comparable sensitivity (RR = 0.821 [0.765, 0.881], P < 0.001), relative to HLC indoor other than CDC-LT for sampling An. funestus. While the two most sensitive exposure-free techniques primarily capture host-seeking mosquitoes, both have substantial disadvantages for routine community-based surveillance applications: the CDC-LT requires regular recharging of batteries while the bulkiness of ITT-C makes it difficult to move between sampling locations. RB placed indoors or outdoors and WET had consistently poor sensitivity so it may be useful to evaluate additional alternative methods, such as pyrethrum spray catches and back packer aspirators, for catching resting mosquitoes

Consequences of the Expanding Global Distribution of Aedes albopictus for Dengue Virus Transmission

The dramatic global expansion of Aedes albopictus in the last three decades has increased public health concern because it is a potential vector of numerous arthropod-borne viruses (arboviruses), including the most prevalent arboviral pathogen of humans, dengue virus (DENV). Ae. aegypti is considered the primary DENV vector and has repeatedly been incriminated as a driving force in dengue's worldwide emergence. What remains unresolved is the extent to which Ae. albopictus contributes to DENV transmission and whether an improved understanding of its vector status would enhance dengue surveillance and prevention. To assess the relative public health importance of Ae. albopictus for dengue, we carried out two complementary analyses. We reviewed its role in past dengue epidemics and compared its DENV vector competence with that of Ae. aegypti. Observations from “natural experiments” indicate that, despite seemingly favorable conditions, places where Ae. albopictus predominates over Ae. aegypti have never experienced a typical explosive dengue epidemic with severe cases of the disease. Results from a meta-analysis of experimental laboratory studies reveal that although Ae. albopictus is overall more susceptible to DENV midgut infection, rates of virus dissemination from the midgut to other tissues are significantly lower in Ae. albopictus than in Ae. aegypti. For both indices of vector competence, a few generations of mosquito colonization appear to result in a relative increase of Ae. albopictus susceptibility, which may have been a confounding factor in the literature. Our results lead to the conclusion that Ae. albopictus plays a relatively minor role compared to Ae. aegypti in DENV transmission, at least in part due to differences in host preferences and reduced vector competence. Recent examples of rapid arboviral adaptation to alternative mosquito vectors, however, call for cautious extrapolation of our conclusion. Vector status is a dynamic process that in the future could change in epidemiologically important ways

Tire-breeding mosquitoes of public health importance along an urbanisation gradient in Buenos Aires, Argentina

Used vehicle tires are a source of mosquito vectors and a means of their introduction and expansion. With the aim of assessing the effects of urbanisation on the main mosquito vectors in temperate Argentina, the infestation levels of Aedes aegypti (L.) and Culex pipiens L. were studied in used tires from highly urbanised cities to low-urbanised small towns in Buenos Aires. Immatures of both species accounted for 96% of the 9,722 individuals collected; the total individuals collected represented seven species. The percentage of water-filled tires containing mosquitoes [container index (CI)] was 33% and the percentage of infested sites [site index (SI)] was 65.2%. These indexes decreased significantly from low to high urbanisation levels for both mosquito species. The relative abundance (RA) of Ae. aegypti immatures was slightly higher toward large cities, but showed no difference for Cx. pipiens. The CI of shaded tires was significantly higher than the CI of exposed tires for both mosquito species. There was no difference in RA values between shaded and sunlit tires. The CI and the SI were highest during the summer across the urbanisation levels, except for Cx. pipiens, which continued to increase during the autumn in small towns. Results related to urbanisation gradient, sunlit exposure and seasonality are discussed