Section 5. Limitations on movement and infection control practices to prevent the spread of infectious diseases. This document is currently under review. Section 6. Communicable Disease Chart.
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It should be recognized that vaccines vary in their efficacy and no vaccine is per cent effective. Vaccine efficacies vary with type of vaccine, manufacturing techniques, storage and handling conditions, skill of administration, age of vaccination, and other host factors. Vaccines for routine use are safe. However, no vaccine is per cent safe. Potential vaccinees, or their parents or guardians, should be screened for contraindications and be informed of potential side effects.
Immunization schedules for the routine control of infectious diseases preventable by immunization vary between countries and are usually based on expert advice to governments and physicians. In addition, the American Academy of Pediatrics periodically publishes comprehensive immunization recommendations in its Report of the Committee on Infectious Diseases Committee on Infectious Diseases At the global level, the WHO publishes recommended immunization schedules and control strategies for vaccine-preventable diseases that are periodically updated by expert advisory groups in the WHO Weekly Epidemiological Record.
In outbreak settings , immunization schedules may be modified. For example, the age of immunization for measles may be lowered to 6 months of age during a measles outbreak. In such situations, people receiving vaccine before the routinely recommended age of immunization should be immunized again at the recommended age since immunization at the earlier age may not have been optimally effective. Immunization programmes include vaccines for routine child, routine adult, travel, selected high-risk populations, and occupational settings.
For example, tetanus toxoid is universally recommended; yellow fever vaccine is only recommended in geographic areas of epidemiological risk i. Beyond protection of the individual, vaccination may also provide a degree of community protection. This phenomenon is known as herd immunity.
Herd immunity is the relative protection of a population group achieved by reducing or breaking the chains of transmission of an infectious agent because a sufficient percentage of the population is immune, that is, resistant to infection through immunization or prior natural infection. When the immunity level in a population becomes such that the effective reproduction number of the disease in that population, R , is less than 1, the disease will eventually die out.
Herd immunity is a complex phenomenon and varies according to the infectious agent, its routes of transmission, the degree to which immunization protects against infection versus only clinically manifest disease, and the distribution of immunization in the population. Typically, for childhood vaccine-preventable diseases, the immunity levels in the population to achieve herd immunity range from around 84 per cent for rubella to over 90 per cent for pertussis.
A particularly difficult problem for vaccine-preventable infectious disease control programmes is complacency by the population that can result from the very successes of the programmes and highlights the continuing need to educate the public and decision-makers. Low disease rates may also focus undue attention on the relatively rare serious side effects of vaccination in relation to current rates of disease.
Such side effects should only be compared in relation to rates of disease and its complications that would occur without immunization programmes. A comprehensive treatment of active immunization is given by Plotkin et al. Passive immunization is a temporary immunity in a host due to the protection afforded by antibody produced in another host. Passive immunity may be acquired either naturally or artificially. Naturally acquired passive immunity is achieved through transfer of maternal antibodies via the placenta.
It is the way that newborn infants are provided with a temporary immunity against many infectious diseases for which the mother is immune. This immunity wanes over time and eventually leaves the infant susceptible to these diseases.
An important use of transplacental immunity as a control measure is in the prevention of tetanus neonatorum neonatal tetanus by immunization of women before or during pregnancy with tetanus toxoid. This is especially important in developing countries where the disease typically occurs when the umbilical cord is cut with an unclean instrument contaminated with tetanus spores or when substances contaminated with tetanus spores are placed on the umbilical stump after delivery.
Control by active immunization of the infant cannot be achieved in sufficient time since the average incubation period is only 6 days with a range from 3 to 28 days. An adequately immunized mother, however, will usually effectively transfer maternal antibodies against tetanus across the placenta to her newborn and prevent tetanus neonatorum. Another example of naturally acquired passive immunity is the relative protection against measles disease in a young infant born to a mother who previously had the disease.
Typically, such infants are immune for approximately 6—9 months or more after birth, depending upon how many residual maternal antibodies are present at the time of pregnancy. Other diseases for which there is usually an effective transplacental immunity in infants, for variable amounts of time, include diphtheria, mumps, poliomyelitis, rubella, and varicella chickenpox.
It should be noted that if the mother is not immune, or if residual maternal antibodies have significantly waned, then the infant may be susceptible to disease. Research is ongoing as to other infectious diseases that may be preventable in the neonate or infant through immunization of the mother before or during pregnancy. Examples include p. Many diseases, however, are not prevented by transplacental immunity.
Breastfeeding is a form of naturally acquired passive antibody transfer to neonates and infants. Breast milk and colostrum contain secretory immunoglobulin A IgA antibodies that may play a protective role in the prevention of infections with such agents as respiratory syncytial virus, rotavirus, and Haemophilus influenzae type b.
Artificially acquired passive immunity is acquired through administration of an antibody-containing preparation, antiserum, or immune globulin.
It has a place in the control of certain infectious diseases in special situations. This immunity also wanes over a relatively short period of time. Examples of the use of artificially acquired passive immunity to control infectious disease include the following:. Susceptible individuals bitten by an animal known or suspected to be rabid should receive rabies immune globulin to neutralize the rabies virus in the wound.
It should be noted that, besides passive immunization with rabies immune globulin, such individuals should also receive active immunization with rabies vaccine. However, epidemics may occur in industrialized countries. Passive immunization with immune globulin may be given to: 1 all household and sexual contacts of patients with hepatitis A, 2 other food handlers in an establishment where hepatitis A has occurred in a food handler, 3 all individuals in an institution where a focal outbreak of hepatitis A has occurred, and 4 people from industrialized countries travelling to highly endemic areas.
It should be noted that vaccines for active immunization for hepatitis A are now available. In suspected cases of diphtheria, the antitoxin must be given as soon as possible because it is only effective in neutralizing diphtheria toxins not yet bound to cells.
Chemoprophylaxis is the prevention of infection or its progression to clinically manifest disease through the administration of chemical substances, including antibiotics. Chemoprophylaxis can also consist of the treatment of a disease to prevent complications of that disease.
Chemoprophylaxis may be specifically directed against a particular infectious agent or it may be non-specifically directed against many infectious agents. The use of antibiotics before surgical procedures is an example of non-specific chemoprophylaxis to prevent wound infections in the postoperative period. Examples of specific chemoprophylaxis are given below. The use of chemoprophylaxis to prevent development of infection is illustrated by using chloroquine to prevent malarial parasitaemia caused by Plasmodium vivax , Plasmodium ovale , Plasmodium malariae , and chloroquine-sensitive strains of Plasmodium falciparum.
Determination of a specific malaria chemoprophylactic regimen is complex. It must take into account the geographic area, the possibility of pregnancy, the weight of an individual dose size for children is determined by body weight , and the risks of adverse reactions to the chemoprophylactic regimen.
Other examples of prevention of development of infection include the following:. An example of the use of chemoprophylaxis to prevent the progression of an infection to active manifest disease is the use of isoniazid INH to prevent the progression of latent infection with Mycobacterium tuberculosis to clinical tuberculosis. People less than 35 years of age who are tuberculosis test positive should receive INH to prevent clinical tuberculosis.
The decision to use INH, especially in individuals more than 35 years of age who are at higher risk of clinical hepatitis from the use of the drug , must be determined based on such information as length of infection, closeness of association with a current case, status of the immune system, presence of acute liver disease, possibilities of pregnancy, and risks of adverse reactions.
Other examples of prevention of progression of an infection to active manifest disease through the use of chemoprophylaxis include the following:. In some situations, establishing screening programmes to detect and treat asymptomatic infections or unrecognized disease in defined populations is useful. An example is the screening for Chlamydia trachomatis in sexual partners of people infected with Chlamydia trachomatis , women with mucopurulent cervicitis, sexually active women 25 years of age or younger, and women older than 25 years of age with risk factors for chlamydia.
A more detailed background on screening as a public health function is given in Chapter An example of the use of chemoprophylaxis to treat an infectious disease to prevent complications of the disease is the use of penicillin or erythromycin in penicillin-sensitive patients to treat streptococcal sore throats caused by Streptococcus pyogenes group A to prevent acute rheumatic fever.
Other examples of prevention of complications of an infectious disease through the use of chemoprophylaxis include the following:. The development of antibiotic resistance can be reduced by using antibiotics only when needed, selecting the proper antibiotic or, in some situations, the appropriate multidrug therapy for the infectious agent, and ensuring compliance with the appropriate regimen for the duration of treatment.
Perhaps the most challenging tool for the control of infectious diseases, and sometimes one of the most powerful and cost-effective, is behaviour change in the host that reduces or eliminates risk of exposure to an agent.
Everyone has developed habits of living lifestyles that are not easily changed. Some of these behaviours are protective against infectious diseases. Others render the individual at higher risk of infection.
Examples of higher risk of exposure to infectious agents through behaviour, and behaviour changes that can have an impact on the chain of transmission, include the following. Many infectious agents are transmitted by the direct transmission route through sexual contact, including Chlamydia trachomatis causing chlamydial genital infections, Neisseria gonorrhoeae causing gonorrhoea, Treponema pallidum causing venereal syphilis, Calymmatobacterium granulomatis causing granuloma inguinale, Haemophilus ducreyi causing chancroid, herpes simplex virus causing herpes simplex, Trichomonas vaginalis causing trichomoniasis, human papillomaviruses causing condyloma acuminate, and HIV causing AIDS.
Abstinence behaviour, that is, refraining from sexual activity with other people, eliminates the risk of transmission of these agents through sexual contact. The delaying of age of first sexual activity avoids the risk of transmission of these agents at an early age. Restricting sexual contact to only between two uninfected people who do not have sexual activity with any other people virtually eliminates the risk of transmission of these agents through sexual behaviours.
The exceptions are due to other routes of transmission of some of these agents e. HIV acquired through intravenous drug use in one partner being transmitted through sexual contact to the other partner.
Limiting the number of sexual partners, and limiting those sexual partners to people who also have few sexual partners, reduces the risk of exposure. However, at the individual level, if one of these sexual partners has an infectious agent transmissible by sexual contact, the risk of transmission may still be high.
Finally, condom use during sexual activity in high-risk situations will markedly reduce, but not eliminate, transmission. A more detailed background on sexually transmitted diseases is provided in Chapter 8. Injection of drugs using non-sterile needles or syringes previously used by other intravenous drug users may transmit infectious agents in blood through the vehicle-borne route of indirect transmission, including HIV causing AIDS; hepatitis B virus causing viral hepatitis B; and Plasmodium vivax, Plasmodium malariae , and Plasmodium ovale causing malaria.
Abstinence behaviour, that is, refraining from intravenous drug use, eliminates the risk of transmission of such agents through contaminated needles and syringes. Using a sterile needle and sterile syringe for intravenous drug use will break the chain of transmission of these infectious agents through this route. Some community public health programmes, in addition to promoting drug abstinence and drug rehabilitation, conduct needle and syringe exchanges and education regarding methods of decontamination to help promote the use of sterile injection equipment among intravenous drug users see Chapter 9.
Eating certain foods may result in exposure to infectious agents through the vehicle-borne route of indirect transmission. These behaviours include consuming raw molluscs by which an infectious agent like the hepatitis A virus can cause viral hepatitis A, p.
Although food and diet are strongly ingrained behaviours, modification of dietary patterns is possible. Cooking foods like beef, pork, and eggs can markedly reduce risk of transmission of infectious agents. In addition, reducing risks by elimination of infectious agents from the food may be possible see the section on control methods applied to the environment. Eating shortly after cooking so that foods are not left standing at ambient temperatures for extended times and paying attention to food recalls are also important behaviours.
Hand washing before eating also reduces risk of transmission of many infectious agents that are spread through direct or indirect routes of faecal—oral transmission, such as Shigella dysenteriae , Shigella flexneri , Shigella boydii , and Shigella sonnei which may cause shigellosis bacillary dysentery , which is estimated to cause , deaths per year with two-thirds of the cases in children under 10 years of age Heymann In certain occupations, many behaviours may result in exposure to infectious agents and should be targets for control programmes in occupational safety and health settings.
Specific examples include the following:. Occupational hazards related to non-infectious materials may predispose an individual to increased risk of infectious diseases. For example, working conditions and behaviours in industrial plants and mines that lead to silicosis due to long-term inhalation of free crystalline silica dust will greatly increase the risk of developing tuberculosis.
Working behaviours appropriate for the particular occupational setting may include wearing protective clothing, eyewear, and gloves; hand washing and changing clothes after work; receiving appropriate vaccinations for the working environment; meticulous adherence to needle disposal and equipment sterilization procedures; and using hooded laboratory benches when handling infectious specimens that can become aerosolized.
Other behaviours that may reduce the transmission of infectious agents include the following:. Some of these other behaviours, like crowding, are conditioned by circumstances such as poverty that are not easily or directly amenable to programmes promoting behavioural change.
Certain rare circumstances exist where a means of avoiding transmission of an infectious disease to a highly susceptible host is to provide reverse, or protective, isolation. Such isolation attempts to protect infection-prone patients from potentially harmful infectious agents. Reverse isolation procedures range from provision of a private room with the use of masks, gloves and gowns by all people entering the room, to elaborate facilities with laminar airflow rooms and sterilization of all food.
Protective isolation is usually conducted for a limited time until the normal immune system recovers, a regimen of passive immunization is begun, or a bone marrow transplant is successful. One tool of control that can be applied to the host is the use of barriers between the host and the infectious agent. The effectiveness of such barriers, however, may be dependent on the behaviour of the host to use them consistently and education to use them correctly.
Examples of barriers include the following:. Improving host resistance though general improvement of the immune system is a non-specific approach, but may be important in certain settings. Moreover, people who are malnourished and succumb to an infectious disease are at higher risk of the disease being of greater severity and leading to other complications. Malnutrition also encompasses micronutrient deficiencies. Vitamin A deficiency, for example, has been linked to higher rates of mortality associated with measles disease.
Correcting vitamin A deficiency, through programmes of supplementation, fortification and dietary modification in high-risk populations, can reduce mortality rates due to measles. A complex interaction exists between infectious diseases, such as diarrhoeal diseases, and malnutrition. A downward spiral of infection may lead to malnutrition that, in turn, leads to more infections, and so on. If unchecked, especially in developing countries, this downward spiral can ultimately result in death.
The special situation of international travel combines many control measures applied to the host already mentioned. The increase in the numbers of travellers, the speed of travel, and the ability to reach areas previously infrequently visited have reduced the effectiveness of surveillance for infectious diseases at ports of arrival and increased infectious disease risks.
Advice for prevention against infectious diseases must be both general and specific. General advice includes such issues as avoidance of eating and drinking potentially contaminated food or drink including ice and swimming or bathing in polluted water.
Specific advice provided by health professionals should be provided based on information about the area to be visited and may include such measures as active immunization against yellow fever, active or passive immunization against hepatitis A, chemoprophylaxis against malaria, repellents against potentially infected mosquitoes, and not walking barefoot in areas of risk for infection with hookworms Strongyloides stercoralis and Strongyloides fuelleborni.
Vector-borne transmission is the only or main route of transmission for many infectious diseases. There exist more than arthropod-borne viruses that may produce clinically manifest diseases in humans. Control of vector-borne diseases includes measures to: 1 change behaviour and create barriers to the susceptible host, 2 reduce or break the chain of transmission of the infectious agent from an infected host to the vector, and 3 directly control the vector population itself.
Chemical, environmental, and biological controls are the primary means of directly controlling the vector population. Chemicals used in the control of vectors that act as digestive poisons, contact poisons, or fumigants include minerals, natural plant products botanicals , chlorinated hydrocarbons, organophosphates, carbamates, and fumigants. Chemical control measures include the following public health interventions:.
The use of spraying for control of mosquitoes is complicated due to concerns about environmental contamination by chemicals such as DDT and dieldrin which have led to them being banned in many countries. In addition, the emergence of mosquito vectors resistant to the insecticides diminishes their effectiveness in many areas.
New methods of application, such as ultra-low-volume spraying of malathion, reduce the amounts of insecticide used. Environmental control of vectors includes the following public health interventions:. It is also important to note that certain development projects may have an impact on the environment that facilitates the growth of vector or intermediate-host populations and results in increased infectious diseases.
Construction of artificial waterways may serve as breeding sites for Simulium fly vectors that can transmit Onchocerca volvulus resulting in onchocerciasis.
Irrigation schemes can foster the growth of snail intermediate hosts required for the transmission of species of Schistosoma resulting in schistosomiasis.
Carefully conducted environmental and health impact studies that consider the impact of a construction project on the vector and intermediate host populations, and ways to modify the project to reduce such populations, are important environmental control measures. Biological control of vectors includes the following public health interventions:.
Control measures may be applied to infected people at the individual level, in the institutional or hospital setting, and at the community level. The hospital setting is a unique situation that requires special efforts to prevent and control nosocomial infections, or healthcare-associated infections HAIs , which are infections that originate or occur in a hospital or other healthcare setting. HAIs are a major problem worldwide. Infection control programmes for hospitals should ideally include the following elements:.
Examples of specific control measures that may be applied to infected humans at the individual, institutional and community levels are detailed as follows. Treatment of people with infectious diseases or subclinical infections may be a control tool for some infectious diseases. Such treatment may or may not have an impact on disease progression in the patient. It should be noted that rapid case detection and prompt application of appropriate chemotherapeutic agents are needed to limit infectivity.
Some important examples of control by chemotherapy include the following:. Recommended treatment regimens include isoniazid INH combined with one or more of the following antibiotics: rifampin, streptomycin, ethambutol, and pyrazinamide.
The WHO has recommended that adherence to a complete course of multidrug therapy be directly observed by another responsible person as part of the DOTS directly observed treatment, short-course global strategy for the control of tuberculosis. Recommended treatment regimens for multibacillary leprosy include the following antibiotics: rifampicin, dapsone, and clofazimine.
A person or animal that harbors a specific infectious agent without discernible clinical disease, and which serves as a potential source of infection. The carrier state may exist in an individual with an infection that is unapparent throughout its course such an individual is commonly known as healthy or asymptomatic carrier , or during the incubation period, convalescence, and post-convalescence of a person with a clinically recognizable disease commonly known as incubatory or convalescent carrier.
Under either circumstance the carrier state may be of short or long duration temporary or transient carrier, or chronic carrier. A chronic carrier of diphtheria, for example, may shed the infectious agent Corynebacterium diphtheriae for 6 months or more, but appropriate antibiotic therapy will usually promptly stop the carrier state. Another example is that of untreated patients with typhoid fever due to Salmonella typhi. Between 2 to 5 per cent of such patients will become permanent carriers.
Treatment with appropriate antibiotics may be effective in ending the carrier state. Antibiotic treatment may not always eliminate a carrier state for some infectious agents. For example, the treatment of people with salmonellosis with an antibiotic may not terminate the period of communicability and can even result in emergence of antibiotic-resistant strains.
However, antibiotic therapy may be still warranted under certain circumstances. In some situations, establishing screening programmes in defined target populations for identification of asymptomatic or unrecognized infections that could be transmitted to others may be appropriate. Such screening should include the necessary follow-up with appropriate chemotherapy and counselling.
An example would be screening close contacts of diphtheria patients with nose and throat cultures for the presence of Corynebacterium diphtheriae. Identified carriers with positive cultures should be treated with appropriate antibiotic therapy.
There are two levels of isolation precautions, namely: 1 a standard precautions level designed for the care of all hospitalized patients, and 2 a transmission-based precautions level designed for the care of hospitalized patients that are suspected or confirmed to be infected by agents spread by contact, droplet, or airborne routes of transmission.
These are summarized from guidelines as follows. Standard precautions are universally applied precautions designed to reduce the risk of transmission by infectious agents from blood; body fluids, secretions, and excretions; non-intact skin; and mucous membranes. Airborne precautions are used, in addition to standard precautions, in settings where patients are suspected or confirmed to be infected by agents transmitted by airborne droplet nuclei.
The essential elements of airborne precautions include preferably placing patients in an airborne infection isolation room AIIR that has monitored negative air pressure if necessary, it is possible to use cohorting of patients with the same active infections ; use of mask respirators N air-purifying respirators ; and limiting patient movement and transport from the room placing a surgical mask on the patient if they are being moved for an essential purpose.
An example of an infectious disease for which patients are recommended to be placed under airborne precautions is a patient in hospital with measles through the fourth day of rash. Although isolation of patients with measles not in hospital is not practical in the general population, schoolchildren should remain out of school until at least the fourth day of rash.
Droplet precautions are used, in addition to standard precautions, in settings where patients are suspected or confirmed to be infected by agents transmitted by droplets. The essential elements of droplet precautions include placement of patients in a private room if necessary, it is possible to use cohorting of patients with the same active infections or maintaining a spatial separation of at least 3 feet between the infected patient and other patients and visitors ; use of a mask when working within 3 feet of the patient; and limiting patient movement and transport from the room placing a surgical mask on the patient if they are being moved for an essential purpose.
Examples of infectious diseases for which patients are recommended to be placed under droplet precautions include pharyngeal diphtheria caused by Corynebacterium diphtheriae and pneumonic plague caused by Yersinia pestis.
Contact precautions are used, in addition to standard precautions, in settings where patients are suspected or confirmed to be infected or colonized by agents transmitted by direct or indirect contact.
Examples of infectious diseases for which patients are recommended to be placed under contact isolation precautions include cutaneous diphtheria caused by Corynebacterium diphtheriae , rubella, and disseminated herpes simplex caused by herpes simplex virus. Two categories of quarantine are as follows Heymann :. Absolute or complete quarantine : the limitation of freedom of movement of those exposed to a communicable disease for a period of time not longer than the longest usual incubation period of that disease, in such a manner as to prevent effective contact with those not so exposed.
Modified quarantine : a selective, partial limitation of freedom of movement of contacts, commonly on the basis of known or presumed differences in susceptibility and related to the assessed risk of disease transmission. It may be designed to accommodate particular situations. Examples are exclusion of children from school, exemption of immune persons from provisions applicable to susceptible persons, or restriction of military populations to the post or to quarters.
Modified quarantine includes: personal surveillance , the practice of close medical or other supervision of contacts to permit prompt recognition of infection or illness but without restricting their movements; and segregation , the separation of some part of a group of persons or domestic animals from the others for special consideration, control or observation; removal of susceptible children to homes of immune persons; or establishment of a sanitary boundary to protect uninfected from infected portions of a population.
Examples of diseases where quarantine may be considered include the following. When measles occurs in such institutional settings, strict segregation of infants is recommended.
Such people include those who live or are in close contact with Lassa fever patients as well as laboratory personnel testing specimens from such patients. Controlling infectious disease transmission by restriction of the activities of people in the community who are potentially infectious to others may be appropriate in certain circumstances.
Examples include the following:. Behaviour change in an infected person to protect others may be difficult to accomplish and often requires continuing education and counselling. However, this should be considered in preventing the transmission of infectious agents in the following situations. Examples of infectious agents transmitted through sexual activities are discussed in the earlier section on control measures applied to the host and in more detail in Chapter 8.
Individuals who suspect that they may have a sexually transmitted disease should be encouraged to have health-seeking behaviours. People with a sexually transmissible infectious agent should be treated and asked to cooperate with health officials to trace their sexual contacts. Patients with diseases such as lymphogranuloma venereum and syphilis, for example, should refrain from sexual contact until all lesions are healed. HIV-infected individuals should be counselled to treat genital ulcer disease promptly since such disease may increase transmissibility of HIV.
Also, HIV-infected people should avoid sexual intercourse with HIV-negative individuals or, if having sexual intercourse with HIV-negative individuals, use methods such as condoms to reduce the risk of transmission. In addition to counselling to abstain from intravenous drug use and establishing drug rehabilitation programmes to help individuals who wish to abstain, promoting behaviour change in the use of injection equipment is important.
Discouraging the sharing of injection equipment and education on methods for the decontamination of needles and syringes for intravenous drug use reduce risks of transmission of infectious agents through contaminated injection equipment. Individuals who should be restricted from handling food e. Food handlers who have an infectious disease that is potentially transmissible through the vehicle-borne means of food should be discouraged from handling food for others. The importance of hand washing, especially after defecation and before handling food, should be stressed.
Other behaviours that may reduce risk of transmission of infectious agents to other people include the following:. A zoonosis is any infectious agent or infectious disease that may be transmitted under natural conditions from vertebrate animals, both wild and domestic, to humans.
In the control of zoonoses many approaches are used that are applied to animals, including the following. Active immunization, or vaccination, of selected animals may protect susceptible animal hosts from certain infectious diseases.
This protection of animals, in turn, prevents susceptible humans from exposure to the infectious agent of those diseases from animals. An example of an infectious disease in animals in which some control can be achieved through immunization in selected animal populations is rabies.
The reservoir of the rabies virus is varied and includes dogs, foxes, wolves, skunks, raccoons, and bats. Preventive measures include efforts to vaccinate all dogs. Other examples of immunization of animals under certain conditions include: 1 immunization of young goats and sheep using a live attenuated strain of Brucella melitensis and calves using a strain of Brucella abortus in areas of high endemicity for brucellosis; and 2 immunization of animals at risk for acquiring infection with Bacillus anthracis that could be transmitted to man causing anthrax.
Restriction is the limiting of the movement of animals and includes isolation and quarantine. Reduction is the killing, known as culling, of selected animals. Selective use of restriction of animals or reduction of animal populations that are infected, or potentially infected, with a zoonotic infectious agent are methods used to decrease or eliminate the opportunity of exposure of susceptible humans, or other animals, to such animals.
The example of rabies can also be used to illustrate the use of restriction or reduction of an animal population to help control an infectious disease. Heymann recommends the following measures:. Register, license, and vaccinate all owned dogs, and other pets when feasible, in enzootic countries; control ownerless animals and strays.
Educate pet owners and the public on the importance of local community responsibilities e. Where animal population reduction is impractical, animal contraception and repetitive vaccination campaigns may prove effective. Detain and observe for 10 days any healthy-appearing dog or cat known to have bitten a person stray or ownerless dogs and cats may be euthanized and examined for rabies by fluorescent microscopy ; dogs and cats showing suspicious clinical signs of rabies should be euthanized and tested for rabies.
Euthanize unvaccinated domestic animals bitten by known rabid animals; if detention is elected, hold the animal in a secure facility for at least 6 months under veterinary supervision, and vaccinate against rabies 30 days before release.
If previously vaccinated, booster immediately with rabies vaccine, and detain for at least 45 days. Cooperate with wildlife conservation authorities in programs to reduce the carrying capacity of wildlife hosts of sylvatic rabies, and to reduce exposures to domestic animals and human populations—such as in circumscribed enzootic areas near campsites, and in areas of dense human habitation.
Other examples of restricting or reducing of animal populations include the following:. Chemoprophylaxis of an animal is using chemical substances e. Chemotherapy of an animal is using these chemical substances to treat an infectious disease in an animal. Both chemoprophylaxis and chemotherapy are control measures that may be used to reduce or prevent the opportunity of an infectious agent from being transmitted from an animal to susceptible humans.
However, caution should be applied in the routine use of chemoprophylaxis in cattle, feed lots, and poultry farms that can promote the emerging of drug resistance and its associated problems in humans as well. Psittacosis is an example of a zoonosis controlled by chemoprophylaxis or chemotherapy in selected animal populations.
The infectious agent, Chlamydia psittaci , may be directly transmitted to humans from infected birds when the dried droppings, p. Imported psittacine species of birds should be placed under quarantine and receive an appropriate antibiotic chemotherapeutic regimen such as chlortetracycline administered in their feed for 30 days.
Another example is chemoprophylaxis in selected dogs at high risk of infection with Echinococcus granulosus. This infectious agent can be transmitted to humans through hand-to-mouth transmission of the tapeworm eggs from dog faeces causing echinococcosis due to Echinoccus granulosus , or cystic hydatid disease.
Control measures applied to the environment are designed to interrupt the routes of transmission by which an infectious agent may be spread through the environment.
Just as the routes of transmission are varied, so, too, are the control methods that can be applied. For more detailed information on the logistics of communicable disease control, please view the World Health Organization WHO field manual.
First, compose the team. This will include public health experts in addition to experts in other fields such as sanitation, nutrition, and statistics. Second, assign tasks, and communicate thoroughly with the host country. Third, prepare a systematic method for data collection alongside statisticians. Data should focus on security, mapping the site, morbidity, mortality, demography, food availability, nutritional status, water, and sanitation among many other topics.
Additionally, coordinate a visual inspection of the area prior to arrival, and interview key leaders of the area. This data should be clear, concise, goal-oriented, standardized, timely, and widely distributed to the team and all involved organizations.
This will help guarantee appropriate funding, and communication with the host country. First, shelter and site planning, involves creating an environment that will avoid packing together individuals tightly as well as avoiding areas with high vector transmission, poor water supply, low security, poor vegetation and soil, and low ability for access ie: close enough to a major center, but not so far as to make travel impossible.
Second, cleanliness covers many aspects of what has already been discussed in the emergency room setting. Of note, full biohazard precautions should be taken with viral hemorrhagic fevers such as Ebola to be discussed below. Water must be available for up to seven liters per person per day in the most extreme situations , and it must be clean.
This can rise up to 20 liters per person per day if taking into account bathing as well as cooking. Diseases spread in contaminated water are plentiful, and their evasion is of utmost importance in emergency conditions. Biological quality less than 10 fecal coliforms per ml of water is important.
Chlorine can be used to disinfect water. Chemical quality is of less importance than biological quality. Waste disposal is important. Pits to dispose of the contents should be created. Liquid waste ie: bathing should be diverted into either storm water drains, or if in a dry area, to an isolated, separate pond, for disposal at a later time. Medical waste could be incinerated, preferably near the camp itself, making sure the contents do not travel to other dwellings.
Otherwise, they should be buried after being sealed in a metal container. Disposing of the dead involves burial to at least 1 meter below earth. In most cases, the bodies should be wrapped in a body bag. Full biohazard precautions should be undertaken for diseases such as Ebola during burial.
The clothing and other contact items of the deceased should be burned. Controlling vectors such as mosquitos Malaria, Dengue, others is essential to reduce specific disease transmission. For mosquitos, chemical environmental control, and use of mosquito nets treated with insecticide and repellent sprays are crucial.
For Malaria, prophylactic drugs can be used. Environmental sanitation is important for Filariasis to prevent breeding of the Culex spp. For other vectors such as flies, mites, lice, and fleas, hygiene, insecticide and repellants are key factors in prevention of disease. Food supply for poor, underdeveloped nations is crucial in preventing disease.
A person with malnutrition will be immunosuppressed and more likely to contract disease as well as less likely to survive the physical toll of any infectious disease. In addition, as with water, sanitation of food is key, and undercooked foods can lead to disease.
A powerful vaccination campaign is imperative for prevention. Globally, vaccines against Measles, Meningococcal Meningitis and Yellow Fever are the most important to public health. Cholera vaccines can also be used. Additionally, prioritize measles vaccines based on age, specifically, between 6 months and 14 years of age.
Epidemic Meningitis can occur in crowded conditions, and is most commonly caused by Neisseria meningitidis. Children aged years old are the most at risk.
The viral disease is transmitted by mosquitos and can have high morbidity when concurrent with other disease outbreak. It should not be given to symptomatic HIV-infected persons. The vaccine has a significant side-effect profile fever, headache, myalgia as compared to other vaccines. Oral cholera vaccines are available for those travelling to endemic areas as well as to people involved in emergency conditions. This involves watching diseases on a continuum, finding trends, and reporting outbreaks earlier rather than later.
This is a data collection phase, similar to the rapid assessment phase, but on a larger scale, and primarily involves interpretation of the data collected in order to create an efficient and effective public health response to the threat. This section describes key features in bulletpoint form regarding a small selection of notable communicable diseases worldwide. Due to the enormous amount of information on this subject, several significant diseases will not be discussed such as meningitis, and pneumonia.
Please consult this manual for in-depth information, and a more exhaustive list. National Center for Biotechnology Information , U.
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