The identification of such transfer mechanisms as water, arthropod vectors, and the asymptomatic carrier has represented some of the major breakthroughs in epidemiology (Rothman, 2002). As a result of these and other epidemiological triumphs, many mechanisms of infection are now known to exist. Infection mechanisms that affect humans can occur horizontally or vertically. A vertical infection mechanism represents a method in which a disease is passed from a parent to a child during the course of reproduction (Nelson, 2007).
On the other hand, a horizontal method of infection is represented by a mechanism that passes pathogens from the infected human to one or more naive, susceptible person (2007). Pertinent to this research are the horizontal vectors, vehicles, and reservoirs, the discussion of which includes a contrasting look at vehicle borne, vector borne, and airborne even iatrogenic transmission of disease pathogens. The vehicle of an infectious disease represents the inanimate object that carries the pathogen or agent from the host or carrier to the receiver.
In certain instances, vehicles have also been termed formites (“EPIC,” 2001). A vector represents a living organism that transports disease from one person to another. A reservoir is a particular long-standing location in which the pathogens are always present and from which the disease can always be contracted. Such locations may include the soil or a water tank (Nelson, 2007). Vehicular transmission represents a mode through which the person (or animal) contracting the disease usually plays an active role in the process (Nelson, 2007).
The vehicle is usually an inanimate object which is approached by the person, who then performs the necessary actions to contract the disease from it. Water as a disease vehicle illustrates this, as the pathogens present within the water are released into the body of the person contracting the disease through his/her decision to take that water and drink it. This is in contrast with vector transmission, where the person contracting the disease plays a much more passive role (2007).
In this mode of transmission, a third party vector (separate from the carrier or hosts) actively takes the pathogen from the primary to the secondary host without any active participation on the part of either host. An example of this is found in the action of the malaria-carrying mosquito, which performs all the work necessary to spread infection from one person to another (Pethleart, et al. , 2004). One interesting type of vehicle borne disease that behaves in a way similar to the vector borne diseases occurs in iatrogenic transmission (Macedo de Oliveira, et al.
, 2005; Nelson, 2007). This type of infection transmission involves the transfer of pathogens from one infected person (or animal) to another via a vehicle or formite. Ironically, in iatrogenic transmission, these agents are then indirectly transferred to a new host through the help of medical personnel. Such transfer may occur through the use of contaminated needles or other medical related instruments. Such iatrogenic transfer may also occur through the administration of vaccines (2002; Nelson, 2007).
Airborne diseases differ from vector borne diseases in that the pathogens are emitted into the air by the primary host and, unlike vectors, the air is inanimate. However, the airborne infection is very similar to the vehicle-borne, as the part played by the person contracting the disease is more active in both than in the vector-borne disease. The role of inhaling the disease is an active (though inadvertent) one. Even the primary host plays a more active role in this form of disease transmission through the act of breathing out the airborne pathogen (Nelson, 2007).
The use that epidemiology makes of this information is to identify the different modes of disease transmission as a means of conducting large-scale public education campaigns to curb the spread of disease. Epidemiologists also identify methods through which the spread of disease may be unavoidable so that further steps can be taken to boost the immunity of the population regarding the disease (Nelson, 2007). Another major use that is made of this information by epidemiologists is to reduce the amount of inadvertent infections that might take place.
For example, the transmission of puerperal sepsis from corpses in the autopsy room to babies in the delivery room via doctors was discovered through epidemiological studies (Hussein & Fortney, 2003). This resulted in education concerning the spread of such pathogens and the improved hygienic practices in the medical profession (2007).
References
Department of Health (2001). Epic Guidelines. (2001). Journal of Hospital Infection. (Supplement). 47. S3-S4. Retrieved November 1, 2007, from http://www. leicestercitypct. nhs.uk/site/policies/clinical_pol/inf_control_primcare/WWW/ 3042_7-122006_NP0170%20Universal%20precautions. doc Githeko, A. K. , Lindsay, S. W. , Confalonieri, U. E. , & Patz, J. A. (2000). Climate change and vector-borne diseases: A regional analysis. WHO. Bulletin of the World Health Organization, 78(9), 1136. Retrieved November 7 2007, from the ProQuest database. Hussein, J. & Fortney, J. (2003). Puerperal sepsis and maternal mortality: what role can new technologies play? International Journal of Gynecology & Obstetrics. 85, S52-S61. Retrieved November 1, 2007, from http://linkinghub.
elsevier. com/retrieve/pii Lo Re, V. , Occi, J. L. , & MacGregor, R. R. (2004). Identifying the vector of lyme disease. American Family Physician, 69(8), 1935. Retrieved November 7, 2007, from the ProQuest database. Macedo de Oliveira, A. , White, K. L. , Leschinsky, D. P. , Beecham, B. D. , Vogt, T. M. , Moolenaar, R. L. , et. al. (2005, June). An outbreak of hepatitis C virus infections among outpatients at a hematology/oncology clinic. Annual Internal Medicine 142, 898-902. Retrieved November 1, 2007, from http://www. annals. org/cgi/content/abstract/142/11/898 Mangili, A.
, Gendreau, M. A. (2005). Transmission of infectious diseases during commercial air travel. The Lancet, 365(9463), 989. Retrieved November 7 2007, from the ProQuest database. Mayo Clinic. (2007). Infectious diseases: How they are spread, how to stop them. Retrieved November 7, 2007, from http://www. mayoclinic. com/infectious-disease/ID00004 National Institute of Health. (2007). Infectious diseases. Retrieved November 7, 2007, from http://www. nlm. nih. gov/medlineplus/infectiousdiseases. html Nelson, K. E. (2007). Infectious disease epidemiology: theory and practice.
Sudbury, MA: Jones & Bartlett Publishers. Pethleart, A. , Prajakwong, S. , Suwonkerd, W. , Corthong, B. , Webber, R. & Curtis, C. (2004, September). Infectious reservoir of Plasmodium infection in Mae Hong Son province, north-west Thailand. Malaria Journal. 3(34). Retrieved November 1, 2007, from http://www. pubmedcentral. nih. gov/articlerender. fcgi? tool=pubmed&pubmedid Rothman, K. J. (2002). Epidemiology: an introduction. New York, NY: Oxford. Wong, S. Y. , & Yuen, K. Y. (2006). Avian influenza virus infections in humans. Chest, 129(1), 156. Retrieved November 7, 2007, from the ProQuest database.