Lecture practical General Principles.ppt

Editor's Notes

• #1: Epidemiology Lecture 8   General Principles of infectious diseases Prevention and Control
• #2: The infectious diseases control and prevention depend on the exact understanding of their epidemiological picture including the chain of infection, transmission and the factors support in the communicability
• #3: Accordingly the principles could be briefed as following: Control of infection in the reservoir Inhibition of Mode of transmission Enhancing host resistance
• #4: Control of infection in the reservoir: It includes all measures related to the reservoir of the infectious agent through one of the methods: Reservoir eradication: the complete eradiation of the reservoir of causative agent is enough to control the infectious disease that result from it. It is important that the reservoir is only the animal reservoir, this method applied to control a number of zoonotic diseases e.g. Bovine TB, Brucellosis, and Rabies. Practically this could not be performed through complete eradication of the reservoir but only to decrease their numbers to a degree that decrease capability of infection transmission. The eradication of domestic animal reservoirs could result in a mass economic loss greater than the risk of the infectious disease. At the same time reaching the wild animal reservoir could be impossible so it is practical if the animal reservoir is easily accessible and eradicated without large economic loss. Reservoir treatment: this mean to give suitable drugs for the reservoir to kill the causative agent within thin the reservoir and to end the reservoir as a source of infection through curing the case. There important points in this regards including; the antibiotic discovery is one of the most important steps in human being development. This method has weak points of; difficult to diagnose all of the cases to be treated, early treatment of the infection which needs early diagnosis, difficulty in carrier treatment, there is no effective antiviral drugs.
• #5: Reservoir Isolation: it is the oldest method for control of infectious diseases e.g. leprosy, plague, cholera. The aim of isolation is to decrease reservoir ability to spread the disease through inducing barriers in place and time between the community and the environmental means. The degree of reservoir isolation depends on the type of the disease and will be regulated by governmental laws. The reservoir isolation effectiveness is limited for the following reasons: applied only to reported cases, isolation not applied for the undiagnosed cases or mild cases, most diseases have severe communicability period at the start before diagnosis, the carriers could be the largest reservoir that could not be diagnosed easily.
• #6: Reservoir treatment: this mean to give suitable drugs for the reservoir to kill the causative agent within thin the reservoir and to end the reservoir as a source of infection through curing the case. There important points in this regards including; the antibiotic discovery is one of the most important steps in human being development. This method has weak points of; difficult to diagnose all of the cases to be treated, early treatment of the infection which needs early diagnosis, difficulty in carrier treatment, there is no effective antiviral drugs.
• #7: Inhibition of Mode of transmission: All the measures being taken to kill the causative agent after exit from the reservoir and before entry to host, also the measures taken toward environmental vehicles and vectors aimed to kill the causative agent, these measures include; health education of people, enhancing personal hygiene, safe water supply and sanitation, vector control, injection safety and sterilization and food safety e.g. cholera, dysentery (water and sanitation), Malaria and yellow fever (vector control).
• #8: Enhancing host resistance: this measure is suitable and important for the developing countries, as the control of infection in the reservoir and cutting the modes of transmission it is not likely to be done completely and faces constrains difficult to be achieved. The sanitation has important role in control of infectious diseases but its projects depend on the general development of the community with indirect effect which is difficult to defence it in front of decision makers while one could defence the vaccination in front of majority even the society is not developed. The enhancing host resistance include following measures; enhance general resistance of host i.e. enhancing health, and nutrition Immunization; enhance host resistance to specific causative agent Active immunization; e.g. Oral Polio Vaccine (OPV), MMR, DPT, TT, HBV Passive immunization; Human Immunoglobulin e.g. Anti-hepatitis A Immunoglobulin, Human Tetanus Immunoglobulin. Animal Immunoglobulin e.g. ATS Chemoprophylaxis: drugs given aimed to prevent infection, or disease incident or prevent complications, it will be given to individuals or at community level. This will be given if there is no effective preventive measures e.g. Penicillin for staphylococcal infections, tetracycline for cholera, Chlroroquine for malaria.
• #9: Chemoprophylaxis: drugs given aimed to prevent infection, or disease incident or prevent complications, it will be given to individuals or at community level. This will be given if there is no effective preventive measures e.g. Penicillin for staphylococcal infections, tetracycline for cholera, Chlroroquine for malaria.