In small-scale farming, humans are in especially close contact with animals, increasing the risk of zoonotic diseases being transmitted.
Photo: J. Boethling

Rural development – the underestimated health hazard?

Rural development and food security once again top the list of priorities for German and international development policy. However, interventions in these fields involve numerous potential health hazards. The author describes some of these in the following article.

The promotion of agriculture and fishing has a key role to play in global strategies to combat hunger and poverty. Yet it is often forgotten that this can involve a whole range of specific risks to people’s health and lives. For example, local, regional or global epidemics often occur in places where people and animals live close together or come into close contact. Agricultural irrigation systems readily become sources of infection with neglected tropical diseases (NTDs) and malaria. The use of antibiotics in agriculture and fish farming contributes to the mounting resistance of pathogens to antibiotics used to treat communicable diseases in humans and animals. Simply producing more food can also lead to the further spread of obesity and with this an increase in non-communicable diseases.

Food safety has to be taken into account within agricultural value chains. There are also many ways in which working in farming can endanger health. All these risks must be considered when planning and implementing cooperation projects in rural development. Preventing or reducing these risks should be an integral component of such projects from the outset.

When man and beast come into contact ...

Weak governments, run-down healthcare systems, specific cultural practices, a belated and initially only half-hearted response from the international community, and a lack of biomedical resources to prevent and treat Ebola – all these contributed to the most recent outbreak of the epidemic in West Africa. 28,500 people in Liberia, Guinea and Sierra Leone have contracted Ebola since December 2013; 11,300 have died. But there is another important factor that should not be overlooked when considering this epidemic: Ebola is a zoonotic disease, an infectious disease that can be transmitted from animals to humans. Although AIDS is not actually a zoonotic disease, all known HI viruses come originally from apes. The further people advance into the wilderness to clear the land for rural development, the closer they come to the virus, perhaps an undiscovered one as yet, that could spark the next deadly pandemic. There was never any danger of that in the case of Ebola, on account of its means of transmission. The world – with the exception of those people affected in West Africa – was lucky this time.

SARS and MERS are also zoonotic diseases. The SARS virus – SARS stands for severe acute respiratory syndrome – that in 2002 and 2003 at first rightly caused global panic, but was then rapidly brought under control worldwide using traditional public health measures, i.e. case finding and isolation – had its origin in civet cats, which are eaten as a delicacy in parts of China.

MERS – properly MERS-CoV (Middle East respiratory syndrome coronavirus) – is a virus first identified in Saudi Arabia in 2012. People suffering from MERS-CoV exhibit flu-like symptoms. To date WHO has been notified of 1,400 cases of MERS-CoV – mainly on the Arabian Peninsula. Of these, 40 per cent have died. More and more studies point to the fact that dromedaries are the source of the human zoonotic infections. As yet there are no indications of continuous transmission of the MERS virus from person to person in the general population.

The Spanish flu of 1918 to 1920, the most deadly pandemic of the 20th century – besides HIV/AIDS – with its death toll of up to 50 million, was likewise a zoonotic disease. The process by which flu viruses are transmitted between humans and animals, that is to say mainly between birds, pigs and humans, is as dynamic and complex as the mutations that the flu viruses can undergo in passing through these various species. Transmission takes place anywhere that humans and animals come into close contact – therefore including and particularly in small-scale farming. That is why – according to leading experts in this field – it is a question not of “if” but only of “when” a new flu virus originating in the animal kingdom starts to make its way round the world. This virus could be as deadly as the one that once caused Spanish flu.

Irrigation and man-made tropical diseases

“Throughout the tropical world, in Africa, Asia and Latin America, the construction of water impoundments, for irrigation and other purposes, in areas of endemic water-related diseases, has inexorably intensified community levels of infection, and also created new areas of transmission”, – so commented JM Hunter, the distinguished American tropical medicine specialist, in a groundbreaking publication right back in 1982. He was referring here in particular to diseases transmissible through mosquitos, other insects or small creatures – known as vectors – in combination with water, such as malaria, lymphatic filariasis, onchocerciasis and especially schistosomiasis (see article "Malaria, shistosomiasis & Co. – The scourge of the 'bottom billion'"). While malaria is often fatal, particularly in children, the other three conditions, which are now included in the neglected tropical diseases, lead if untreated to chronic illness and severe disability. Even then, Hunter warned of a lamentable lack of cooperation between the agriculture and health sectors and called for urgent remedial action.

Then, in 1992, a comprehensive monograph for many regions of Africa, Asia and Latin America published by the World Health Organization showed, country by country, how, because of these NTDs and malaria, agricultural irrigation programmes in the previous decades had led to a deterioration in the health of hundreds of thousands, or even millions, of people who settled near these programmes. The report referred particularly to the negative health impacts of small earth dams built in Africa in their thousands in the 1970s and 1980s to irrigate the fields or as animal watering places.

Staff of GTZ, the German agency for technical cooperation, reported specific experience of this in German development cooperation programmes in Mali in the 1980s. They found that in the area surrounding agricultural irrigation projects the prevalence of schistosomiasis was six times higher than in places without irrigation.

Because the prevalence of schistosomiasis around natural water sources was three times lower than at artificially created ones, they concluded that schistosomiasis in Mali during the 1980s was essentially a man-made health problem. In addition, a more recent cost-benefit analysis by the World Bank relating to an agricultural irrigation project in Ethiopia found that almost a third of the project’s benefit in terms of enhanced production and household incomes was cancelled out by its health costs – including the increased number of cases of malaria and schistosomiasis and the resulting days of sickness. That is why the report recommends that such programmes should only be carried out in areas where malaria and schistosomiasis are rare or can be easily controlled. The latter is now in principle the case everywhere – unlike in the 1970s and 1980s. Simple, proven and cost-effective methods to achieve this are available (see article Malaria, shistosomiasis & Co. – The scourge of the 'bottom billion).

Antibiotic resistance

The World Health Organization recently declared the worldwide rise in pathogen resistance to the antibiotics currently available to treat infectious diseases to be one of the greatest global health challenges of our time. Improper and excessive use of antibiotics in healthcare worldwide is contributing significantly to the development of this resistance. However, at the same time there is no question that the use of antibiotics in farming – whether to maintain the health of livestock or as an aid in fattening – drastically encourages the spread of resistant bacteria. This is particularly the case in places where there is little state regulation of the market in antibiotics and other pharmaceuticals.

More food, obesity and non-communicable diseases

However sensible the aim of increasing yields is as part of rural development programmes to tackle  poor productivity, especially in African farming, it must of course come with a health warning. Non-communicable diseases are on the rise in Africa as well. Cardiovascular diseases in particular are often diet-related, and obesity is an important risk factor. Although a third of children in developing countries are small for their age – on account of their malnutrition and the prevalence of infectious diseases – there are now more overweight people living there, purely in terms of numbers, than in countries with higher incomes. For this reason, too, rural development projects designed to increase yields must not focus just on producing more food, but on producing the right food. It is however doubtful whether that alone is enough to make people plan a more balanced diet. That is why additional, evidence-based measures are probably needed to try to influence people’s eating habits and lifestyle and encourage them to adopt a healthy diet and way of life.

Risks to food safety

The most significant agricultural sources of food-related illnesses are zoonotic pathogens, bacteria in contaminated water and mycotoxins. Health risks caused by salmonella and campylobacter are especially relevant for food safety in livestock production. These bacteria enter the food production chain from the digestive tract of livestock raised on farms and smallholdings. Contaminated water can also present a risk, for example when inadequately treated wastewater is used to irrigate crops. In addition, food safety in tropical regions is threatened by the frequent occurrence of mycotoxins, poisons produced by moulds. The most prominent example is that of aflatoxin, produced by the fungus Aspergillus flavus, which can contaminate maize and nuts, particularly in hot, humid regions. The consumption of foods contaminated with aflatoxins can cause liver damage and even liver cancer.

Work-related health risks in farming

Every year 170,000 farmers, fishermen and agricultural workers worldwide die as a result of their jobs. Working in farming is one of the most dangerous occupations of all. Agricultural machinery presents the greatest dangers, but using agrochemicals and other toxic or allergenic substances is also hazardous. The WHO estimates that worldwide there are up to 5 million cases of pesticide poisoning each year among farm workers and in the rural population, predominantly in developing countries. Infectious diseases transmitted from animals to humans are especially dangerous for those working in agriculture. Smallholders and their families in particular are often exposed unprotected to these infections. There are also health problems caused by noise, vibration, dust and dirt.

Cooperation projects require a health component

The examples given highlight a number of potential negative consequences for health from development projects promoting agriculture. They are a burning issue for German development policy, which has recently made rural development a top priority as part of the government’s special initiative “One World – No Hunger”.Therefore, in order to prevent these potentially serious side-effects on human health resulting from rural development cooperation projects, or to mitigate their consequences, it is imperative to:

  • actively monitor infectious animal diseases as part of livestock disease information systems and make practical provision for combating epidemics affecting humans and animals (epidemic preparedness);
  • ensure that wherever irrigation programmes are carried out infectious tropical diseases are managed appropriately at the same time and brought under control. Of particular importance in this context are schistosomiasis, the filiariases and malaria;
  • regulate markets for pharmaceuticals and especially antibiotics for humans and animals in partner countries and monitor the use of antibiotics in animal and fish farming;
  • take coherent steps to guarantee the safety of food “from field to fork”;
  • recognise and prevent work-related health risks (accidents, infections, poisoning) for small-scale farmers and agricultural workers, and in the case of illness make appropriate healthcare provision for the sick people and their families.

In conclusion, it is essential to determine the health risks of programmes to promote rural development at the planning stage as part of a stand-
ardised participatory health impact assessment, so that appropriate countermeasures can be taken when a project is implemented.

Ebola and neglected tropical diseases – the case of Sierra Leone
In the wake of the Ebola epidemic it was feared that the efforts to combat the disease would shift the focus away from other major diseases such as malaria, and especially from the neglected tropical diseases (NTDs). This was indeed initially the case in Sierra Leone. As long ago as 2005 the government set up a national NTD programme in partnership with the US Agency for International Development, whereby 30,000 voluntary community workers helped to organise mass preventive chemotherapy treatment (mass drug administration, MDA) to control schistosomiasis, filariasis, soil transmitted helminths (STH: whipworms, roundworms and hookworms) and river blindness (onchocerciasis) and ensured continuous comprehensive coverage for a number of years. However, with the pressure of the Ebola epidemic all NTD activities had to be halted in 2014. When the epidemic had abated – since the beginning of November the country has officially been free of Ebola – MDA was successfully resumed in 2015. As was recently reported from Sierra Leone, 75 per cent of all communities in endemic regions are now being reached again. In a recently implemented MDA campaign 1.4 million people are said to have received preventive chemotherapy for lymphatic filariasis and STH. As things stand, Sierra Leone could be one of the first African countries to successfully control schistosomiasis and geohelminthiasis and to eliminate lymphatic filariasis and river blindness.

Dr med. Matthias Vennemann, MPH (JHU)
International Health Consultant
Münster, Germany


References and further reading

When man and beast come into contact ...
World Health Organisation WHO: Zoonoses and the Human-Animal-Ecosystems Interface. Available at:

Vennemann, Matthias and Benn, Christoph: C.: SARS – Lehren aus der ersten neuen Epidemie des 21. Jahrhunderts. Entwicklungspolitiik 12/2003

Glasmacher, Susanne and Kurth, R: Globaler Alarm. Spektrum der Aissenschaft Dossier 3/06: Seuchen II: Available at:

WHO: Middle East respiratory syndrome coronavirus MERS-CoV. Available at:

Taubenberger, Jeffery K. and Morens, David M.: 1918 Influenza: the Mother of All Pandemics. Emerging Infectious Diseases, Vol. 12, No. 1, January 2006.  Available at:

CDC: Transmission of Influenza Viruses from Animals to People. Available at:

What Will the Next Influenza Pandemic Look Like? Available at:

Irrigation and man-made tropical diseases
Hunter JM, Rey L, Scott D.: Man-made lakes and man-made diseases. Towards a policy resolution. Soc Sci Med. 1982;1611:1127-1145. Available at:

Hunter, J. M. et al.:  Parasitic diseases in water resources development: the need for intersectoral negotiation. WHO 1993. Available at:

The distribution and spread of schistosomiasis in relation to water resources development in Mali. Brinkmann UK1, Korte R., Schmidt-Ehry, B: Trop Med Parasitol. 1988 June, 392:182-5. Available at:

Ersado, Lire: Small-scale irrigation dams, agricultural production, and health – theory and evidence from Ethiopia. World Bank Policy Research Working Paper 3494, January 2005. Available at:

Antibiotic resistance
WHO’s first global report on antibiotic resistance reveals serious, worldwide threat to public health. Available at:

Woolhouse, Mark und Farrar, Jeremy: Benötigen wir einen Weltrat für Antibiotikaresistenzen? Available at:

Aarestrup, Frank: Antibiotika raus aus dem Schweinestall. Available at:

More food, obesity and non-communicable diseases
Mozaffarian D. et al.: Population Approaches to Improve Diet, Physical Activity, and Smoking Habits. Circulation, August 20, 2012. Available at:

Risks to food safety
FAO: Prevention and control of mycotoxins. Available at:

Work-related health risks in farming
IAASTD: Health and Nutrition. Issues in Brief.  Available at:

NTD Control
Hotez, Peter J.  et al.: Control of Neglected Tropical Diseases. N Engl J Med 2007; 357:1018-1027. Available at:

Celebrating NTD Success Stories: Sierra Leone’s Inspiring Progress in the Face of Ebola. Available at:

WHO: Investing to overcome the global impact of neglected tropical diseases: third WHO report on neglected diseases 2015. Available at:

The London Declaration | Uniting to Combat NTDs. Available at:

The Global Network for Neglected Tropical Diseases:
Deutsches Netzwerk gegen vernachlässigte Tropenkrankheiten (DNTDS) e.V.:


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