Category Archives: Climate and health

It is difficult to forecast malaria epidemics

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ResearchBlogging.org

Malaria transmission is complex and is associated with climate. However, simple attempts to extrapolate malaria incidence rates from averaged regional meteorological conditions have proven unsuccessful. This study by Loha and Lindtjørn describes P. falciparum malaria incidence models linked with meteorological data in south Ethiopia.

Variability in the models was principally attributed to regional differences, and a single model was not found that fits all locations. Past P. falciparum malaria incidence appeared to be a superior predictor than meteorology. The study concludes that future efforts to model malaria incidence may benefit from inclusion of non-meteorological causes.

This study is agrees with a recent Nature paper by Gething and colleagues. They describe the malaria decline takes place during global warming. The reasons for decline might be non-climatic causes such as better treatment and prevention. The paper by Loha and Lindtjørn shows that factors affecting malaria incidence also varies with a region.

Locally, we are examining possible associations between temperature, rainfall, mosquito development and malaria in both lowlands and highlands in Ethiopia. Through this research, we hope to improve our understanding of the local variations in malaria epidemiology.

Loha, E., & Lindtjørn, B. (2010). Model variations in predicting incidence of Plasmodium falciparum malaria using 1998-2007 morbidity and meteorological data from south Ethiopia Malaria Journal, 9 (1) DOI: 10.1186/1475-2875-9-166

Gething, P., Smith, D., Patil, A., Tatem, A., Snow, R., & Hay, S. (2010). Climate change and the global malaria recession Nature, 465 (7296), 342-345 DOI: 10.1038/nature09098

Global warming and malaria

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ResearchBlogging.orgA recent article by Gething and colleagues in Nature (May 20th, 2010) shows that malaria has declined the past century. The decline has been largest in areas with less malaria transmission.

What is new in this paper is that the malaria decline takes place during global warming. The reasons for decline might be non-climatic factors such as better treatment and prevention. Their research addresses malaria on large scales, and the situation might be different in local areas.

Linking changes in temperatures to variations in malaria epidemiology is justified by known biological effects on life-cycle stages of the Anopheles vector and Plasmodium parasite. For example increasing temperature to 30o C results in shortened sporogonic period of the Plasmodium parasite, and differently for P. falciparum and P. vivax. Higher mean daily temperatures are not favourable for vector survival. Increased temperature speeds up development of the aquatic stages of the vector.

Therefore, some propose developing tools to forecast malaria epidemics. We use different terminology to describe malaria risks, and distinguish between long-term forecasts, early warning and early detection of epidemics.

Long-term epidemic forecasting is based on climate forecasting, and many use information such as the El Niño Southern Oscillation indices as added information to predict epidemic risks months in advance over large geographical areas. Such a forecast allows time for the population to prepare for a possible epidemic in the following malaria season.

Malaria epidemic early warning is based on surveying transmission risks to predict timing of an increase because of abnormal rainfall or temperature. Often, such risks are influenced by population vulnerability such as history of low malaria transmission. Such predictions can give lead times of weeks to months.

The long-term and early warning should however be distinguished from epidemic early detection. This involves noting the beginning of an unusual epidemic, and offers short lead time (days to weeks) for preparation of preventive measures.

We are studying the association between temperature, rainfall, mosquito development and malaria in both lowlands and highlands in Ethiopia. Through this research, we hope to improve our understanding of the local variations in malaria epidemiology. Our aim is to examine if the spatio-temporal distribution of surface temperature and rain can predict malaria epidemics (both long-term forecasting, and malaria epidemic early warning). We base this on an assumption the nature of the link between climate and occurrence of malaria is constant and similar for different settings.

Gething, P., Smith, D., Patil, A., Tatem, A., Snow, R., & Hay, S. (2010). Climate change and the global malaria recession Nature, 465 (7296), 342-345 DOI: 10.1038/nature09098

Malaria mortality declines in Ethiopia

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ResearchBlogging.org BBC World Service citing the Global Fund (Early Evidence of Sustainable Impact on Malaria) reported yesterday that malaria mortality declined by almost 50% in Ethiopia. The Global fund report states a 54% decline in malaria cases and 48% decline in malaria deaths.

Are such figures true? Working on malaria research projects in south Ethiopia I can confirm that fewer malaria patients are admitted to health centres and hospitals. Our preliminary data show that people use bed nets, community health workers diagnose and treat malaria cases, and malaria deaths do not occur as often as previously.

But, we have learned that malaria is a focal disease. In our research on malaria and climate we observe the last years have been dry in large parts of south Ethiopia. After the rains we first see increases in the mosquito densities followed by increases in malaria cases. There are more mosquitoes and cases after the heavy rains in early 2010, compared with 2009. Although we believe that malaria control efforts are effective, we need more time to get a full picture on the links between interventions, malaria sickness and death and naturally occurring variations.

Recent demographic data show decline in under-five mortality rates in Ethiopia from 204 to 123 per 1000 live births between 1990 and 2005. Ethiopia shows good progress was observed in controlling HIV/AIDS and malaria, but not for tuberculosis (Otten M et al, 2009; Accorsi S et al, 2009). Although a downward trend was observed in the maternal mortality ratio, it is too early to reach any firm conclusion about the possibility of achieving MDG5 because of sampling variability (Hogan M et al, 2010).

The good achievements in controlling malaria and increasing immunisation coverage show that scheduled routine interventions is well handled by the current health care system. However, interventions that rely on clinical services near to households with 24h availability, such as skilled care at birth, are weak. With the good achievements on malaria and immunization coverage, Ethiopia now needs to strengthen health institutions such as hospitals and health centres.

Otten, M., Aregawi, M., Were, W., Karema, C., Medin, A., Jima, D., Kebede, W., Gausi, K., Komatsu, R., Korenromp, E., Low-Beer, D., & Grabowsky, M. (2009). Initial evidence of reduction of malaria cases and deaths in Rwanda and Ethiopia due to rapid scale-up of malaria prevention and treatment Malaria Journal, 8 (1) DOI: 10.1186/1475-2875-8-14

Accorsi, S., Bilal, N., Farese, P., & Racalbuto, V. (2010). Countdown to 2015: comparing progress towards the achievement of the health Millennium Development Goals in Ethiopia and other sub-Saharan African countries Transactions of the Royal Society of Tropical Medicine and Hygiene, 104 (5), 336-342 DOI: 10.1016/j.trstmh.2009.12.009

Hogan, M., Foreman, K., Naghavi, M., Ahn, S., Wang, M., Makela, S., Lopez, A., Lozano, R., & Murray, C. (2010). Maternal mortality for 181 countries, 1980–2008: a systematic analysis of progress towards Millennium Development Goal 5 The Lancet DOI: 10.1016/S0140-6736(10)60518-1

2010 AAAS

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During the last week I have attended the Annual Meeting of AAAS in San Diego. This is the largest gathering of interdisciplinary research. For me it was an interesting meeting.

I learned that much of the current research in biology and health is interdisciplinary, and mathematical modelling plays an important role in the research.

It was also interesting to learn about efforts to stop the spread in southern Africa:

  • Antiretroviral treatments (ARVs) and universal testing could stop the spread of Aids in South Africa within five years, a top scientist says.
  • In Botswana, a research group from Los Angeles is evaluating if one antiretroviral drug (monotherapy) can be given to disease free individuals and thus reduce disease incidence.

One of the main themes in many of the sessions were the increasing worry about public distrust in science. Several Leading scientists admitted the recent controversies surrounding climate research have damaged the image of science as a whole.

The President of the US National Academy of Sciences, Ralph Cicerone, said the controversial e-mail exchanges about climate change data had caused people to suspect that scientists “oppressed free speech” and that some feel that scientists are suppressing dissent.

Several speakers agreed that scientists needed to be more open about their findings. Recent polls, including one carried out by the BBC, have suggested that climate scepticism is on the rise.

Some highlights at the meeting is found here.

The Bergen Summer Research School

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The Bergen Summer Research School aims to produce and disseminate research-based education to address some important global challenges. These challenges include Climate and environmental changes, health challenges and new diseases as well as widespread and severe poverty of certain groups and regions. These issues call for interdisciplinary spaces for debate, and joint learning.

Short description for the 2010 course on Research Methods in Climate Change and Health:

Global climate change may lead to changes in extreme weather events such heatwaves, droughts, extreme rainfall and severe storminess. This may affect human health by bringing about changes in the ecology of infectious diseases. To address the impact of climate change on affect human health a broad research approach including social, demographic, and economic aspects is needed.

The course will explore the links between human health and the earth’s environment, and consider the implications of those links for human health in a changing environment.

The central objective of the course is to help develop and strengthen local and regional scientific knowledge and capacity to deal with the impacts of climate variability and climate change on human health.

For full course description and syllabus: click here (PDF)

The course is by Bjerknes Centre for Climate Research and Centre for International Health at University of Bergen

Course leaders are:

  • Bernt Lindtjørn, Professor, University of Bergen, Centre for International Health
  • Asgeir Sorteberg, Associate Professor, University of Bergen, Bjerknes Centre for Climate Research
  • Ellen Viste, Research Fellow, University of Bergen, Geophysical Institute
  • Thorleif Markussen Lunde, Research Fellow, University of Bergen, Centre for International Health