Posted by Liban Ahmed
Sun, 12 Feb 2017
Parasite infection and its issues. Why an integrated approach is the way forward? (By Diego F. Najera)
Parasitic distribution and infection is an issue of relevance to global and local health, veterinarians and agricultural economy. Parasites can cause death, overt clinical disease and sub-clinical disease in their hosts. It is estimated that approximately 1 billion people are affected by Neglected Tropical Diseases (NTDs) with reports of multiple issues in the infected such as growth retardation, cognitive impairment, poor health and death. Other effects can include anaemia, inflammatory bowel disease and in some cases death, depending on worm burden.
Moreover, figures obtained by WHO (2016) for soil transmitted helminth (STH) infections indicate that approximately 1.5 billion people have contracted STH infections predominantly in the aforementioned regions. Malaria is recognised as the leading parasite in amounting to death toll. In 2010, approximately 660,000 deaths were recorded (CDC, 2013). Malaria is notable in countries like Peru, Venezuela, Colombia, Ecuador and countries in sub-Saharan Africa (e.g. Kenya, South Africa, The Gambia) (WHO, 2010).
Spread and development of parasite infection is linked to poor healthcare legislation, poor sanitation schemes, limited access to safe drinking water, geophagia, use of night soil as fertiliser, host age, environmental and climatic factors among others (Bailey C et al, 2013). Most parasites will grow, reproduce and invade organ systems which can lead to illness and in some cases death to the host (Healthline, 2016).
For farmers, parasitic infection is an issue. Bovine PGE causes infects livestock and farmers economic disruption and losses. Such losses can include; treatment of affected stock (e.g. medicine, veterinary fees), replacement of stock, loss of productivity, pasture management and in some cases death (Ramesh P et al, 2015).
Therefore, development and implementation of different control methods to reduce parasite infection and losses associated with them are highly sought after. In the face of increased chemical-resistance and environmental adaptation in parasites, an integrated approach to parasite control is necessary (George J et al, 2004).
In a review by De Silva P and Marshall J (2012), it was suggested that malaria transmission was not limited to rural areas, as first believed but rather a trend was found indicating the adaptation of malaria vector species to urbanisation. Parasites benefit from a wide range of possible hosts. The parasite will establish a non-mutual relationship with its host. Parasite hosts vary and can include any of the following; humans, dogs, cats, pigs, livestock, insects and plants.
Multi-host parasites sustain transmission in spite of intensive human-focused disease control activities. Multi-host zoonoses are infectious diseases which can be transmitted from humans to animals (vice-versa), approximately 60% of human diseases and 75% of emerging diseases are zoonotic (Cleaveland S et al, 2001). Resistance, adaptation and a wide selection of hosts for the parasite, contribute to the difficulties faced when devising an effective control scheme.
Therefore, it seems that implementing a single-faceted strategy to control parasite spread and growth is no longer effective. Rather, a complex integrated approach is needed which combines practices and strategies (chemical and non-chemical) from multiple fields to tackle ever-changing challenges public health specialists, medics, veterinarians and farmers face.
By Diego F. Najera
References:
Bailey C et al. (2013) Factors associated with parasitic infection amongst street children in orphanages across Lima, Peru. Pathogens and Global Health Vol. 107, No. 2, 52-57.
Cattle Parasites. (2014) Integrated parasite control on cattle farms 2014 [online]. Available from: http://www.cattleparasites.org.uk/guidance/manual/COWS%20Integrated %20parasite%20control%20on%20cattle%20farms.pdf. [Accessed 7 January 2017]
CDC. (2013) Malaria press release 2013 [online]. Available from: https://www.cdc.gov/media/releases/2013/p1031-malaria-cases.html. [Accessed 10 January 2017]
CDC. (2015) Insects 2015 [online]. Available from: https://www.cdc.gov/parasites/insects.html [Accessed 5 January 2017]
CDC. (2016) About Parasites 2016 [online]. Available from: https://www.cdc.gov/parasites/about.html. [Accessed 5 January 2017]
Cleaveland S et al. (2001) Diseases of humans and their domestic mammals: pathogen characteristics, host range and the risk of emergence. Philosophical Transactions of the Royal Society Vol.356, No.1411, 991999.
De Silva, P and Marshall, J. (2012) Factors contributing to Urban Malaria Transmission in Sub-Saharan Africa: A Systematic Review. Journal of Tropical Medicine Vol. 2012, 1-10.
George J et al. (2004) Chemical Control of Ticks on Cattle and the Resistance of these Parasites to Acaricides. Parasitology Vol.129, 353-366.
Healthline. (2016) Parasitic infections 2016 [online]. Available from: http://www.healthline.com/health/parasitic-infections#Overview1. [Accessed 2 January 2017]
Levine, G. (1991) Sexually Transmitted Parasitic Diseases. Primary Care Vol.18, No.1, 101-128.
Ramesh P et al. (2015) Parasitic Gastroenteritis in a Merino Sheep Farm. Scholars Journal of Agriculture and Veterinary Sciences Vol.2, No.4, 312313.
Schillhorn van Veen, T. (1997) Sense or nonsense? Traditional methods of animal parasitic disease control. Veterinary Parasitology Vol.71, No.2-3, 177-194.
Thamsborg S et al. (2010) Alternative approaches to control of parasites in livestock: Nordic and Baltic perspectives. Acta Veterinaria Scandinavica Vol.52, No.1, 1-5.
TPMA. (N.D.) Benefits of IPM N.D. [online]. Available from: http://www.tpma.org/_organizational/ipm_benefits.htm. [Accessed 22 December 2016]
WHO. (2010) Malaria 2010 [online]. Available from: http://www.who.int/gho/malaria/en/. [Accessed 24 December 2016]
WHO. (2016) Soil-transmitted helminth infections 2016 [online]. Available from: http://www.who.int/mediacentre/factsheets/fs366/en/. [Accessed 22 December 2016]
Students for Global Health 