Study session 2  Prevention and also Control that Communicable Diseases and also Community Diagnosis


In the very first study session, you learned around the straightforward concepts in the infection of communicable diseases. The knowledge you obtained will assist you to recognize this research session due to the fact that they space interlinked. In the first section, you will learn about the different ways of classifying communicable diseases. Following classification you will discover the viewpoints in prevention and control of communicable disease. This will assist you in identifying appropriate measures for the prevention and also control that communicable illness that you, as a Health expansion Practitioner, and other health and wellness workers will put right into place in her community. This study session creates the communication for research sessions later on in this Module on details diseases such as malaria, tuberculosis and also HIV/AIDS. Finally, you will learn how to apply the methods of community diagnosis come assess and also prioritise actions come prevent and also control the key communicable diseases in her community.

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Learning Outcomes for examine Session 2

When you have studied this session, you must be may be to:

2.1 Define and also use correctly all of the key words printed in bold. (SAQs 2.1, 2.2 and 2.4)

2.2 recognize the two key ways of classifying communicable diseases, and illustrate your usefulness. (SAQs 2.1 and also 2.2)

2.3 Describe and also give instances of prevention and control procedures targeting the reservoir of infection. (SAQs 2.3 and 2.4)

2.4 Describe and give examples of prevention and also control measures targeting the setting of transmission of communicable diseases. (SAQs 2.3 and also 2.4)

2.5 Describe and give instances of prevention and also control procedures that defend the susceptible organize from communicable diseases. (SAQs 2.3 and 2.4)

2.6 explain the simple processes involved in community diagnosis and also give instances of exactly how you would use these methods. (SAQ 2.5)

2.1  Classification of communicable diseases

Communicable diseases can be classified in various ways into teams with comparable characteristics. Category will help you to select and also apply ideal prevention and also control measures that are usual to a course of communicable diseases. In this section you will learn the basis for each way of classifying communicable diseases and its relationship to your practice. This will certainly be clarified using examples of communicable conditions that you may already be familiar with.

In research Session 1 you have actually learned the types of infectious agents which can be offered for category of communicable diseases. Apart from this, there are two key ways the classifying communicable diseases, i beg your pardon are essential for you to know. The classification can be clinical or epidemiologic, as explained in box 2.1.

Clinical classification is based upon the key clinical manifestations (symptoms and signs) that the disease.

Epidemiologic category is based on the main mode of transmission of the disease.

2.1.1  Clinical classification of communicable diseases

As stated in crate 2.1, this classification is based upon the main clinical manifestations of the disease. This method of category is important in help you come treat the symptoms and also signs that are typical to (shared by) people who suffer from different diseases. Clinical group is illustrated by the instance given below.


Figure 2.1 diseases whose key manifestation is diarrhoea space clinically classified as diarrhoeal diseases. The usual treatment because that this course of condition includes fluid replacement.

Some diseases are classified as diarrhoeal diseases. The key clinical symptom is diarrhoea, which means passage of loose stool (liquid faeces) 3 or more times every day. Two examples of diarrhoeal diseases are shigellosis and cholera. (Further details about these diseases are in study Session 33 of this Module). People with watery diarrhoeal an illness suffer native loss of fluid from their bodies. Therefore, also though the transmittable agent can be different, together in the examples of shigellosis and cholera, the usual management the patients through diarrhoeal an illness includes fluid replacement (Figure 2.1).

Other clinical classifications

Another clinical group refers to diseases qualified as febrile illnesses, since they all have the main symptom the fever, because that example, malaria. Respiratory diseases are one more clinical classification; their main symptoms incorporate cough and also shortness of breath, together in pneumonia.

Diseases have plenty of symptoms and also signs. Together a Health extension Practitioner, you will need to decide i m sorry symptom is the key one for classification. Utilizing the an approach of clinical category will help you decision to act the key symptom. Friend will be able to identify the key symptoms an ext easily as soon as you find out about details diseases after that in this Module. Bear in mind that for most diseases, treatment of the key symptom is only supportive (that is it will certainly not cure the disease). Therefore, you have actually to provide treatment specific to the transmittable agent. This will be debated later in this Module under the specific diseases.

2.1.2  Epidemiologic classification

This classification is based on the main mode of infection of the infectious agent. The prestige of this group for you is that it permits you to select prevention and control actions which are common to (shared by) communicable diseases in the same class, so as to interrupt the setting of transmission. To clarify the importance of epidemiologic classification, consider the following examples.


Figure 2.2 One an approach of dealing with unsafe water is boiling before drinking. (Photo: Wikimedia Commons at wiki/ Category:Boiling_water)

Cholera and typhoid fever space two various diseases which can be transmitted by drink contaminated water. Therefore, they space classified as waterborne diseases, utilizing the epidemiologic classification. The common prevention procedures for the 2 diseases, despite having different transmittable agents, encompass protecting water resources from contamination and also treatment that unsafe water before drinking, for instance by cook (Figure 2.2) or including chlorine.

The main varieties of epidemiologic group are described in crate 2.2.

Based on the mode of infection of the transmittable agent, communicable diseases can it is in classified as:

Waterborne diseases:transfer by gulp down of contaminated water.Foodborne diseases: transmitted by the ingestion of contaminated food.Airborne diseases: sent v the air.Vector-borne diseases: sent through vectors, such as mosquitoes and flies.

Suppose if you room working in your wellness facility, a 20 year-old man concerns you complain of high heat accompanied through violent shivering (rigors), vomiting and also headache. A blood examination for malaria found evidence the Plasmodium falciparum. Assume the he gained the parasite after being bitten by infected mosquitoes. Exactly how would you classify this man’s health problem, making use of two different classifications?

Clinically the disease is classed as a febrile illness since fever to be the key clinical manifestation. Making use of epidemiologic classification, the condition is classed as vector-borne since it was transmitted through the mosquito.

When you have studied more about malaria in later on study sessions, friend will have the ability to see how the clinical group as a febrile disease can assist you in the management of the patient. As he has a high fever, in enhancement to treatment through anti-malarial drugs, you have to take procedures to lower the fever by giving him paracetamol. The epidemiologic classification of the disease as vector-borne helps you to select measures come prevent and control malaria in the community, for instance by advocating security from mosquito bites by utilizing bed nets, and also drainage of little collections that water whereby mosquitoes breed.

In the next section we will discuss the general approaches come prevention and also control of communicable diseases at neighborhood level.

2.2  General ideologies in the prevention and control of communicable diseases

You now have actually a working knowledge of factors affiliated in the chain of disease transmission (described in examine Session 1), and also how to classify communicable diseases. This expertise will help you to identify prevention and also control actions that deserve to be used at each link in the chain. As soon as we say prevention it refers to procedures that are applied to stop the occurrence of a disease. Once we say control it refers to measures that are used to prevent transmission after ~ the condition has occurred. Many of the steps for prevention and also control that communicable diseases are reasonably easy and can be applied using the community’s very own resources. You have crucial role in educating the general public to apply these procedures effectively.

You have actually learned the prevention and also control that communicable diseases involves interventions to rest the chain the transmission. Can you recall the 6 factors affiliated in the chain?

They room the transmittable agent, the reservoir, the path of exit, the mode of transmission, the path of entry, and the susceptible host.

We deserve to simplify the discussion of prevention and control procedures acting on the chain of transmission by merging this six determinants into 3 groups:

Infectious agents in the reservoir the infection and also the route of exit from the reservoir are debated under the heading ‘reservoir’.The ‘mode of transmission’ is the 2nd category the we will certainly discuss.The route of entry and also the susceptible organize are discussed under the heading ‘susceptible host’.
2.2.1  Measures targeting the reservoir that infection

During your ar practice, the prevention and also control procedures you will undertake rely on the type of reservoir. In this section we will talk about measures because that tackling human and animal reservoirs. As soon as you conference an infected person, you must undertake the measures described below.

Diagnosis and treatment

First, friend should have the ability to diagnose and treat instances of the disease, or refer the patience for therapy at a greater health facility. There are two means to recognize an infected individual: as soon as a patient pertains to you (Box 2.3, on the following page, defines how girlfriend should technique a patient in stimulate to recognize a case), and by screening (discussed below). Identifying and also treating instances as early as possible, reduces the severity that the condition for the patient, staying clear of progression to complications, disability and death; and also it likewise reduces the threat of transmission to others.

The an initial step is come ask about the main complaints of the patient.Then ask about the existence of various other related symptoms and also risk factors.Examine the patient physically to detect indicators of any diseases girlfriend suspect.Finally, refer the patience for laboratory examinations if easily accessible (e.g. Blood examination because that malaria).

Screening describes the detection of an infection in an individual who does not show any kind of signs or symptom of the disease. The is lugged out using particular tests dubbed screening tests. Screening will help you come detect an infection early and also organise suitable treatment so regarding reduce complications and also prevent transmission to others. An instance of screening that may be familiar to you is screening the blood of pregnant females for HIV infection.


You will learn more details around tuberculosis in examine Sessions 13–17 the this Module.

Following detection that an transmittable disease, you might need to separate patients from rather to prevent transmission to healthy and balanced people. This is dubbed isolation. That is not indicated for every infection, yet it is vital to isolate people with very severe and also easily sent diseases. Because that example, one adult situation of energetic pulmonary tuberculosis (‘pulmonary’ method in the lungs) should be preserved in isolation in the an initial two mainly of the extensive phase that treatment. The isolation period lasts until the danger of transmission from the infected human being has lessened or stopped. The duration and level of isolation differs in between different diseases, as you will discover in later on study sessions.

Cases of communicable illness should be reported to a nearby health center or woreda health Office periodically, using the nationwide surveillance guidelines.

Animal reservoirs

When infected pets are the reservoir connected in the infection of communicable diseases, different measures have the right to be undertaken against them. The form of action depends top top the animal reservoir, and also ranges from treatment to destroying the infected animal, relying on the usefulness the the animal and also the accessibility of treatment. For example to prevent and also control a rabies outbreak, the actions to be taken are usually to ruin all stray dogs in the area, and vaccinate pet dogs if the owner deserve to afford this protection and also the vaccine is available.

2.2.2  Measures targeting the setting of transmission

The steps that deserve to be used to interrupt infection of transmittable agents in water, food, various other vehicles and also by vectors, are described below.

The detailed discussion the interventions come prevent and control all these modes of transmission have the right to be uncovered in the Hygiene and Environmental health Module.


Measures to prevent transmission of infection due to contaminated water encompass boiling the water, or adding chemicals choose chlorine. Disinfection is the procedure of killing most, but not all, contagious agents exterior the body by direct exposure to chemicals. Adding chlorine is one an approach of disinfecting water. Physics agents can also be used, for example filtering water v a box of sand, or pouring it through numerous layers of good cloth. Faecal air pollution of water should likewise be prevent by protecting water sources and also through suitable use that latrines (Figure 2.3).


Figure 2.3 suitable use that latrines can assist prevent breeding of vectors, and contamination the hands, food and also water. (Photos: left, WaterAid, right, Pam Furniss)

Measures to prevent transmission in contaminated food include washing raw vegetables and fruits, boil milk, and also cooking meat and also other food item thoroughly prior to eating. Air pollution with faeces can be prevent by hand washing and proper usage of latrines.

Other vehicles

Measures come tackle transmission in or ~ above vehicles other than water and food include:

Contaminated objects like household utensils for cooking, eating and drinking should be washed with soap and also water. Contaminated clinical instruments and clothing can be sterilised, disinfected or correctly disposed of.

Sterilisation involves destruction of all develops of micro-organisms by physical heat, irradiation, gas or chemistry treatment. The difference between disinfection and also sterilisation is that disinfection death most, however not all, micro-organisms. Disinfection have the right to be done making use of alcohol, chlorine, iodine or heater at the domestic level; whereas sterilisation needs to use too much heating, irradiation or solid chemicals like a high concentration the chlorine.


Measures versus vectors include avoiding breeding the vectors, through ideal disposal that faeces and also other wastes, eradication of reproduction sites, and also disinfestation. Disinfestation is the procedure of damaging or removing small animal pests, particularly arthropods and rodents, existing upon the person, the clothing, or in the setting of an individual, or on residential animals. Disinfestation is usually accomplished by utilizing chemical or physical agents, e.g. Spraying insecticides to damage mosquitoes, and removing lice native the body and clothing.

2.2.3  Measures targeting the at risk host

The measures described below assist to safeguard the susceptible host either from ending up being infected, or from occurring the phase of infectious condition if they space exposed come the transmittable agents.

As you already know from research Session 1, vaccination refers to administration of vaccines to rise the resistance the the susceptible hold against details vaccine-preventable infections. For example, measles inoculation helps to defend the kid from measles infection, and BCG vaccination provides some protection from tuberculosis (Figure 2.4).


Figure 2.4 vaccination can assist to protect against transmission the communicable diseases by increasing the resistance of susceptible hosts. (Photo: AMREF, Ethiopia/ Demissew Bezuwork)

Chemoprophylaxis is pronounce ‘keem-oh-proff-ill-axe-sis’; (‘chemo’ refers to medical drugs, and ‘prophylaxis’ way ‘an activity taken to prevent a disease’).

Chemoprophylaxis refers to the drugs given to exposed and susceptible master to protect against them from emerging an infection. For example, people from non-malarial locations who are going come a malaria endemic area have the right to take a prophylactic medicine to avoid them from developing the an illness if they end up being infected with malaria helminth from a mosquito bite.

Maintaining a healthy and balanced lifestyle

Proper nutrition and exercise enhances a person’s wellness status, supports the efficient functioning of their immune system, and increases resistance come infection.

Limiting exposure come reservoirs of infection

Measures required to decrease contact with reservoirs of epidemic include:

Condom usage to avoid transmission of HIV and also other sexually sent infections (STIs).Use of insecticide treated nets (ITNs) over the bed at night, insect repellants and also wearing protective apparel to prevent diseases transmitted by insect vectors. Wearing surgical or very clean gloves and also clean protective garments while assessing patients, particularly if they have wounds, or the examination involves the genital area. Keeping an individual hygiene, choose taking a day-to-day bath and washing her hands frequently. Hand washing with soap and also water is the simplest and also one of the most reliable ways to stop transmission of countless communicable illness (Figure 2.5). The times when hands must be wash are shown in box 2.4.

Figure 2.5 Hand washing with soap and water is the simplest and also most effective method to avoid transmission of communicable diseases. (Photo: Basiro Davey)
After making use of the toiletAfter handling animals or animal wasteAfter transforming a diaper (nappy) or clean a child’s bottom Before and also after prepare foodBefore eatingAfter blowing the nose, coughing, or sneezingBefore and after caring for a ailing personAfter dealing with waste material.

Now you have many an excellent ideas top top what measures can be undertaken come prevent and control communicable diseases. However, you have actually to use these methods effectively in order come prevent and control the most crucial communicable conditions in your community. But how do you determine these diseases? In the next section we will certainly answer this question.

2.3  Community diagnosis

In order come select and also apply efficient prevention and control measures, you an initial have to determine which form of conditions are usual in the ar you are working with. How do you execute that? The technique is called community diagnosis and it requires the following four steps:

Data collection methods and data analysis are described in the Module on health Management, Ethics and Research.

Data collectionData analysisPrioritising problemsDeveloping an action plan.

Let’s begin with data collection and also proceed to the others action by step.

2.3.1  Data collection

Data collection refers to collection data around the wellness problems existing in the community. This is vital as that will assist you to have great ideas around the kind of problems current in the area whereby you work. Where carry out you get helpful data worrying the health difficulties in your community? The following sources the data can be used:

Discussion with neighborhood members about their main health problemsReviewing documents of the health and wellness services utilised by the communityUndertaking a ar survey or a small-scale projectObserving the dangers to health current in the community.

After collecting data it need to be analysed to make definition out of it.

2.3.2  Data analysis

Data analysis describes categorising the whole of the data you collected into groups so regarding make definition out that it. For circumstances you have the right to assess the magnitude of a condition by calculating that prevalence and also its incidence indigenous the numbers of cases you recorded and the number of people in the population in your community.

Prevalence rates and incidence prices can additionally be expressed together ‘per 10,000’ or ‘per 100,000’ in much larger populations, e.g. The a an ar or a entirety country.

Prevalence refers to the total number of cases existing in the populace at a point in time, or throughout a given period (e.g. A certain month or year). The variety of cases can be an ext usefully analysed through calculating the prevalence rate in the community: to carry out this you divide the total number of cases you recorded in a given period into the total number of people in the population. The an outcome is express ‘per 1,000 population’ in a community as little as a kebele. Because that example, intend that in one year you record 100 cases of malaria in a kebele that 5,000 people: because that every 1,000 people in the kebele, there to be 20 malaria cases in the year. For this reason the ubiquity rate that malaria in that kebele is expressed together 20 situations per 1,000 civilization in that year.

Calculating the pervasiveness rate is much more useful than simply counting the variety of cases, since the population size in her kebele can adjust over time. The pervasiveness rate bring away account of changes in the variety of people, therefore you deserve to compare the pervasiveness rates from different years, or compare the rate in her kebele v the rate in one more one.

Incidence refers just to the number of new cases the a an illness occurring in a offered period. The incidence rate is calculate by dividing the full number of new cases that the disease in a certain period of time into the total variety of people in the population, and also is expressed as ‘per 1,000 population’.

If there to be 10 new cases the cholera in a kebele the 5,000 human being in one month, what is the incidence rate of cholera every 1,000 populace in that period?

The incidence rate in this instance is two brand-new cholera situations per 1,000 population.

As a health professional working in a community impacted by several health difficulties at the exact same time the is an overwhelming to resolve all the troubles at once. Therefore, friend should offer priority come the most necessary ones first. Yet how carry out you prioritise? You are going to see exactly how to do that next.

2.3.3  Prioritising health problems

Prioritising refers to placing health difficulties in order of their importance. The components that friend should take into consideration in prioritising are:

the size of the problem: e.g. Just how many instances are developing over what period of time?the severity that the problem: exactly how high is the risk of major illness, handicap or death?the feasibility that addressing the problem: are the prevention and control steps effective, obtainable and affordable through the community?the level of issue of the community and also the government around the problem.

Health problems which have a high magnitude and also severity, which have the right to be quickly solved, and are major concerns of the community and also the government, are provided the greatest priority. After ~ prioritising which disease (or diseases) girlfriend will provide most urgent attention to, the next step is to build an activity plan.

2.3.4  Action plan

An action plan sets out the ways in i beg your pardon you will certainly implement the interventions forced to prevent and control the disease. It has a list of the objectives and also corresponding interventions to be carried out, and also specifies the responsible bodies who will it is in involved. It likewise identifies the time and also any equipment needed to implement the interventions. Once you have prepared an activity plan you need to submit that for discussion with your supervisor and also other officials in the woreda health Office to obtain their approval. Then implement the work-related according to your plan.

Now that you have actually learned the straightforward concepts and also methods relating come communicable diseases in general, it is time for you to move on to think about the diagnosis, treatment, prevention and control of details diseases. In the next two research sessions, you will learn around the bacterial and also viral illness that have the right to be prevent by vaccination.

Summary of study Session 2

In examine Session 2, you have actually learned that:

Communicable illness can be classified based on their clinical or epidemiologic features. Clinical group is based on the main clinical manifestations of the condition (e.g. Diseases qualified by diarrhoea room classified together diarrheal diseases; diseases qualified by fever space febrile diseases).Epidemiologic divide are based upon the setting of transmission and include foodborne, waterborne, airborne and also vector-borne diseases.Prevention and control procedures for communicable illness may target the reservoir of infection, the mode of transmission, or the vulnerable host.Measures against a person reservoir incorporate treatment and isolation. Measures versus animal reservoirs deserve to be therapy or ruining the animal.Measures versus transmitters favor food, water, other vehicles, and vectors, incorporate hand washing v soap, reliable use of latrines, destruction of reproduction sites, disinfection, sterilisation and disinfestation. Actions to protect susceptible hosts encompass vaccination, keeping an individual hygiene, usage of bed nets and use that condoms.Community diagnosis of health troubles involves data collection; data analysis; prioritising interventions based upon the magnitude and severity the the problem, the feasibility that addressing it, and the level the concern; and making and implementing one effective action plan.

Self-Assessment concerns (SAQs) for research Session 2

Now that you have completed this study session, you can assess how well friend have accomplished its finding out Outcomes by comment the concerns below. Create your answer in your research Diary and discuss them v your guardian at the following Study support Meeting. You can examine your answers v the note on the Self-Assessment inquiries at the end of this Module.

Tuberculosis (TB) is typical in Ethiopia. Its main clinical manifestations encompass chronic cough and also shortness of breath. Using this information, which group of communicable diseases can you use to TB and to which course does TB belong?


Using the provided information, the classification could be based on the clinical manifestations the the condition (cough and also shortness that breath); appropriately tuberculosis is classed as a respiratory disease.

How would you classify pulmonary tuberculosis utilizing the epidemiologic method? What is the main importance of together classification?


Pulmonary tuberculosis is classified epidemiologically as an airborne disease. Such classification helps friend in using prevention and control measures against the disease.

Suppose in a details rainy season friend diagnosed malaria in several people who concerned you search treatment. Then, you undertook the following measures:

a.You treated each patient with the suitable drug.b.You mobilised the neighborhood to eradicate breeding sites the mosquitoes.c.You offered health education on the proper use of bed nets.

Which variable in the chain of disease transmission space you targeting with each that the over measures?

Answera.Treatment of every patient targets the human reservoir.b.Eradication of breeding sites targets the mode of transmission.c.Bed net use targets the susceptible host.

Which the the complying with statements are true and also which space false? In each case, explain your reasoning.

A Isolation of the susceptible hold is advised because that the duration of the incubation duration of a severe and also easilytransfer disease.

B Sterilisation refers to the destruction of all develops of micro-organisms by physics or chemistry agents such together alcohol and also chlorine.

C Vaccination and also vector control target the infected organize so regarding prevent transmission of infection.


A is false. That is true that isolation is applied for severe and easilytransfer diseases, however it is applied to the infected hosts (not the susceptible hosts) until the danger of transmission is diminished or stops.

B is true. Sterilisation kills all develops of micro-organisms, uneven disinfection which kills most however not every forms.

C is false. Vaccination largely targets the vulnerable host and vector manage targets the setting of transmission.

Suppose amongst the conditions you have determined in your community, two room malaria and ascariasis (infection through ascaris worms). Stop say the pervasiveness rate the malaria is 90 every 1,000 population and the pervasiveness rate that ascariasis is 200 every 1,000 population.

a.If you should prioritise tasks to control one of these diseases, what other criteria should you consider? b.Malaria is a more severe disease than ascariasis. Let’s say that interventions because that both illness are equally feasible, but the community and government are an ext concerned about malaria. So, considering all the factors, come which disease do you give greater priority because that prevention and control?
Answera.The various other criteria come be considered include the severity that the diseases, the feasibility the implementing reliable interventions, and also the concern of the community and also the government.b.Malaria has priority in 2 out of the five criteria: the is severity, community and government concern, whereas ascariasis has actually priority in just one criterion, which is the higher prevalence. Both illness have equal priority in feasibility that implementing interventions. Therefore, malaria have to be given higher priority because that prevention and control.
◄Communicable conditions Module: 2. Prevention and Control that Communicable Diseases and Community Diagnosis

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