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Contents
1. Epidemiology.
2. Screening
3. Communicable Diseases
4. Non-communicable Diseases.
5. Family Welfare
6. Population and Demography
7. Health Care Administration
8. Nutrition
9. MCH
10. Environment
11. International Health
12. Health Information Systems
13. Concepts in PSM
14. Occupational Health
15. Social Medicine
16. IEC
Epidemiology
1. Define Epidemiology A. Epidemiology is defined as the distribution and determinants of disease frequency or health events in man. Modern day epidemiology is different from the earlier period where it just referred to as study of epidemics. It now includes comprehensive methods for control of diseases, including non-communicable diseases. Distribution refers to the time; place and person characteristics of disease while the determinants (what determines disease) are generally characterized as agent, host and environmental factors. Since freedom from disease allows an individual to remain healthy, it is also important to find out how and why individuals do not suffer from disease and remain healthy. Such analyses will help in finding solutions to disease and maintaining good health. 2. What are the uses of epidemiology? A. The major uses of epidemiology are: a. To assess the magnitude or burden of disease in a community. It, therefore, helps in studying the occurrence of disease in a population. b. To assess the health status of communities. It, therefore, helps in establishing a community diagnosis. c. To search for determinants of disease. To find out how and why disease is caused is a major use of epidemiology. d. To estimate an individual’s risks and chances of suffering from a disease and to establish the prognosis in an individual suffering from disease. e. To plan comprehensive health services, including specific strategies and ways and means of implementation. f. To evaluate strategies and interventions for disease control. Such evaluation helps in identifying weaknesses and to suggest remedial measures for the future. Evaluation of costs and benefits or effectiveness of specific interventions is also an integral use. g. To complete the natural history of disease. In a hospital setting only the terminal cases are seen and how disease starts and presents in its initial stages is only possible by studying disease in the community. h. To forecast future disease trends. i.To identify syndromes. 3. What is the epidemiological triad? A. Disease is caused by an interaction between agent, host and environmental characteristics. When all three are in harmony, health is ensured but maladjustment in their relationships leads to disease. These three factors together constitute the epidemiological triad.
4. What is the difference between retrospective and prospective studies? A.Retrospective studies start after a disease has occurred and the investigator looks back in time to find out what agents or characteristics (including habits) the individuals were exposed to and which could lead to disease. Case control studies are examples of retrospective studies. In prospective studies individuals are identified before occurrence of disease and they are followed up to see which individuals develop disease. The characteristics or exposures of these individuals to disease causing agents are compared with the characteristics of individuals who do not suffer from disease. This helps in searching for determinants of disease. 5. What is a case control study? A. A case control study is an epidemiological study where a group of individuals with disease are compared with a group of individuals who are not suffering from disease in terms of specific disease causing exposures. Since the starting point is a group of people who already have suffered from the disease, this is labeled as a retrospective study. Advantages of case control studies
- Relatively quick and easy to undertake.
- Relatively cheap to undertake.
- Only method useful in rare diseases.
- Not enmeshed in problems of follow-up as the data is collected at one point in time.
- Can be used to study the effect of many exposure variables on a single disease outcome. Drawbacks of case control studies
- Prone to selection and recall bias.
- Can’t measure relative risk or provide incidence estimates.
- Sometimes the occurrence of the exposure in terms of time, i.e. whether it occurred before the disease may be difficult to decipher.
- Can’t be used for rare exposures.
- Designing the study is not an easy task. 6. What is a cohort study? A. Cohort studies are forward looking, i.e. they look for the development of disease in a group of individuals (the cohort) free of the same at the beginning. The group is followed up over a period of time. During this period some persons will develop the disease under study while others will remain free of the disease. The characteristics (and exposure to disease causing factors) are compared between those who suffer from disease and those free from the disease. The literal meaning of the term ‘cohort’ refers to a group that shares similar characteristics. Thus, it implies that one needs to identify groups of populations who are free of the disease being studied and who are similar in all respects, except the specific exposure variable or characteristic whose effect is being related to the disease being studied. These groups are then followed up for the period of time that it takes for the disease to develop. 7. What is a Randomized Controlled Trial? A. A randomized controlled trial is an experimental method where individuals are randomly allocated to an experimental or a control group and the effect or response of a drug or intervention is compared between the two groups. The two key features are ‘randomization’ and ‘controlled’. To ensure that there is no bias on part of the investigator, these trials are ‘blinded’ – single blind means the patients do not know what the intervention is; ‘double’ blind means that neither the patient nor the researcher knows what the drug/ intervention package is while ‘triple’ blind means that the analysis team also does not know which is the experimental and which is the control group till the study has been completed. 8. What is a Community Trial? A. A community trial is a modification of the clinical trial where instead of individuals being allocated to experimental or control groups, whole communities are randomly allocated to receive specific interventions and analysis is done for whole communities rather than for individuals in the communities. Vitamin A supplementation trials, iron supplementation or iodine supplementation trials are all examples of community trials. 9. What is a vaccine trial? A. When a randomized control trial is done to test the efficacy of a vaccine in preventing disease, it is called a vaccine trial. 10. What is the difference between Descriptive and Analytical Epidemiology? A. The descriptive methods are mostly concerned with the distribution of disease/health condition, while the analytical methods are concerned with the determinants of disease/health condition.
17. Give some examples of epidemic diseases, which have occurred in India recently? A. The recent outbreak of plague in India where cases were not seen for many years is an example of an epidemic. HIV/AIDS is also a disease with epidemic proportions. Epidemics of dengue, JE are also reported from time to time. Epidemic diseases need not necessarily be communicable diseases. Therefore, WHO also looks at smoking as an epidemic. 18. What is a pandemic? A. An epidemic which breaks out across many continents is called a pandemic – i.e. occurring across the world. 19. Name some pandemic diseases A. HIV/AIDS and smoking can be called as modern day pandemics as they have affected millions of people across the world. Cholera was one of the most common diseases, which assumed pandemic proportions. Drugresistant tuberculosis is also a pandemic. Plague was also pandemic in historical times. 20. What are endemic diseases? Name some endemic diseases A. The constant, continuous or usual presence of a diseasein a defined geographic area or delimited territory is called an endemic disease. Hyperendemic refers to a persistent intense transmission in an area while holoendemic means a disease staring early in life and affecting most of the population. An endemic disease may become an epidemic if the number of cases usually seen suddenly increase in proportion. Malaria, tuberculosis, leprosy, filariasis, etc. are examples of endemic diseases. 21. What is prevalence rate? A. The proportion of persons suffering from a specific disease out of the population normally residing in that area, at a particular point in time, is called the prevalence rate. It includes both the new cases as well as the old cases occurring in the area at the point in time when the examination was undertaken. The point in time can be one day or one year or more depending upon how much time it takes to examine the population residing in an area. The persons suffering form the numerator while the population from which they hail is called the denominator. It should be seen that the numerator is part of the denominator. For example, if female genital discharge is being studied, the denominator should only include the population who are at risk of suffering from a disease i.e. women. Prevalence rate can be represented as a percentage if a disease is common or as per 1000 or 100,000 population if disease is rare. 22. What is incidence rate? A. Incidence rate refers to the number of new cases occurring in a population over a specified period of time. The numerator should be part of the denominator as in prevalence rate but unlike as in prevalence rate only new cases are considered. If a case started before the reference period but is continuing to the present, it is not considered in the numerator. E.g. if the reference period is from 1st Jan – 31st Jan 2002, cases,which started before 1st Jan 2002 but are still suffering will not be included in the numerator. Incidence rate is generally depicted as per 1000 or 100,000. 23. What is the relationship between prevalence and incidence? A. Prevalence of a disease is the product of incidence and the duration of disease ( P= I xD). Therefore, prevalence of a disease depends not only on the actual number of people who develop a disease but also on the duration of a disease. For short duration diseases like common cold, the prevalence and incidence are almost identical while for chronic or long- standing diseases like tuberculosis, leprosy or blindness the prevalence is always much higher than the incidence. 24. How does prevalence of a disease increase? A. The prevalence of a disease can increase in the following conditions:
- The duration of the disease is very long (i.e. chronic conditions)
- The level of incidence i.e. the higher the incidence, the larger is the prevalence.
- Improved methods of diagnosis that lead to detection of larger number of cases than before.
- Availability of effective treatment, which prolongs life such that the individual lives longer while still suffering from the disease.
- A sudden migration of cases into an area where the disease was not very common earlier. 25. How does prevalence of a disease decrease? A. – A very short duration of the disease (applicable to the acute disease conditions).
- A very low incidence of disease
- Lack of proper diagnostic equipment or skills for the detection of disease.
- Diseases with a high mortality such that very few individuals survive
- Out migration of diseased individuals 26. In which disease conditions is prevalence more appropriate and why? A. Prevalence is most appropriate in long-standing or chronic diseases as the window period in which a diagnosis can be established is much higher and therefore, cases will not be missed during a survey. On the other hand, short duration diseases would occur and recover so fast that they cannot be examined (or are missed) at a specific point in time.
27. In which diseases is incidence more appropriate and why? A. Incidence is most appropriate in disease of a short duration as such diseases may occur more than once during a reference period and all the episodes may not be captured if the prevalence of the disease were to be measured. E.g. If a study were done on diarrhea, if the number of people suffering from diarrhea in a one-year period was measured, it would always be much lower than the number of episodes of diarrhea that the population staying in that area would suffer. 28. What do you mean by a primary case? A. The first case of a disease which occurs in a community/area is called the primary case. Many a time, the primary case may not be recognized as the disease comes to notice much later. Only by historical review can, the possible primary case, be located in such a case. In some disease like acute conjunctivitis a number of primary cases may occur almost at the same point in time. In such a scenario, the primary cases are referred to as “Co–primaries” 29. What do you mean by an index case? A. The first case, which comes to the attention of the health authorities in an area, is referred to as the index case. Such a case may or may not be the primary case. 30. What is Secondary Attack Rate? A. The secondary attack rate refers to the number of cases occurring among contacts of a primary case within the known incubation period of the disease. The denominator refers to the number of susceptible contacts who are in close touch with the primary case. However, if whether a person among the contacts has previously suffered from the specific disease and developed immunity is not known, then all the contact should be considered in the denominator. Such persons are usually other members of the family / neighborhood / institution who stay with the primary case. 31. What is a secular trend? A. If the pattern or trend of disease frequency changes only over many years then it is called a secular trend. 32. What is a cyclic trend? A. If the occurrence of disease changes over a short duration of time like a year, it is called a cyclic trend. Most epidemic diseases in India show a cyclic trend. Some diseases change in frequency over seasons and such changes are referred to as seasonal changes – Measles and chickenpox are examples of such diseases. 33. What is herd immunity? Give examples where it is important? A. The immune status of a group of people/community is called herd immunity as it is the immune status of the ‘herd’ of people. For many communicable diseases, an outbreak of disease is only possible if the level of immunity is sufficiently low and there are a large number of susceptibles in the population. In diseases like poliomyelitis, diphtheria, measles etc., herd immunity plays an important role. However, in a disease like tetanus or rabies where every individual is at risk unless specifically protected, herd immunity plays no role. 34. What is a nosocomial infection? A. An infection occurring in a patient in a hospital or other health-care facility and in whom it was not present or incubating at the time of admission or arrival at a healthcare facility is called a nosocomial infection. It refers to diseases transmitted from a hospital. Usually such infections are more difficult to manage as they are generally resistant to most of the common antibiotics. Nosocomial infections also include those infections, which were contacted in the hospital but manifested after discharge, and also infections suffered by staff members if they contacted the infection from the hospitalized patients.
Screening
35. What do you understand by the term screening? A. Screening denotes the search for unrecognizeddisease or defect in apparently (or outwardly)healthy persons by the application of rapid diagnostic tests, examinations or procedures. The basic objective of screening is to facilitate an early diagnosis so that the prognosis can be improved by remedial action. 36. What is mass screening? A. When all members of a population are screened for disease it is called mass screening. This is very costly and the yield of cases is usually too small to warrant such a screening procedure. 37. What is high-risk screening?
A. In active immunization, a live/killed vaccine is injected and the body reacts by producing antibodies, which make the individual immune and protect against attack by infectious agents. Active immunity is also achieved after suffering from a disease like measles, chickenpox, etc. Active immunity is long lasting and more effective in preventing future disease. The only drawback is that it takes time for the body to produce antibodies and therefore active immunization is usually not useful in an emergency. Rabies is an exception because the incubation period of the disease is long.
47. What is the incubation period for chickenpox? A. Incubation period is 7-21 days and commonly it is 14-16 days. 48. How does chickenpox spread? A. It can affect people of all ages but most commonly children below 10 years are affected as they do not have protective antibodies. It is most commonly spread due to respiratory secretions from infected persons, which are teeming with the virus. Crusts of chickenpox are not infective. 49. What is the incubation period for measles? A. The incubation period of measles ranges from 8 –16 days with an average incubation period of 10 days. 50. What are the different life threatening complications of measles? A. Common life-threatening complications of measles include broncho-pneumonia and diarrhea. Encephalitis can also occur rarely. 51. When is measles most infectious? A. Measles is most infectious 4 days before to 5 days after the rash appears. 52. How does the rash of measles differ from the rash of chickenpox? A. An eruptive rash appears in measles as dark red macules or maculopapular granules, first evident behind the ears and at the junction of the scalp and forehead and then spreading over the face, trunk and limbs, very rapidly. The rash lasts for 4-6 days and disappears in the same order in which it appeared. It dries off leaving a brawny discoloration of the skin. The rash in chickenpox has a centripetal distribution – first appearing on the trunk and then spreading towards the periphery. The palm and soles are not affected. The rash is seen mostly on the flexor surfaces and appears on the very first day and thereafter in crops, evolving very rapidly. The lesions are superficial, unilocular and are surrounded by a red areola. They are small, elliptical and mostly discrete with no umblication. 53. What is German measles? A. German measles is Rubella and is a mild eruptive fever like measles. It is caused by Rubella virus. 54. What are the complications if a pregnant mother gets Rubella? A. The special public health significance of Rubella is that a child may be born with congenital defects like deafness, microcephaly, microphthalmia, PDA, septal defects and other malformations, which are called the Congenital Rubella Syndromme, if the mother is infected during pregnancy. The frequency of congenital defects is 20-25% if infection occurs in 1st trimester and less after that. 55. What is MMR vaccine and how and when should it be given? A. MMR vaccine is measles, mumps and rubella vaccine, which is a live, attenuated vaccine and is administered as a single IM dose after 1 year of age. If measles vaccine has been administered to a child at 9 months, MMR should be given at 15 months of age. 56. Which diseases do you know of which are planned to be eradicated? A. Gineaworm, poliomyelitis and leprosy are three major diseases, which are on the eradication agenda. Smallpox was the first disease, which was successfully eradicated. 57. What are the diseases caused by rodents? A. Plague, murine typhus, salmonellosis, Weil’s disease, rate bite fever, trichinosis, rickettsial pox and lymphocytic choriomeningitis are diseases caused by rodents. 58. How can you distinguish Culex from Anopheles mosquitoes? A. The anopheles lays eggs singly on water while culex lays eggs in clusters or rafts of 100-200 eggs. Culex eggs are oval with no air floats while anopheles eggs are boat shaped with lateral air floats. The larvae of anopheles have no siphon tubes, lie parallel to water surface and have palmate hair on abdominal segments, while in culex, two siphon tubes are present, they hang at an angle and have no palmate hair. Adult anopheles sit against the wall at an angle, have spotted wings and palpi are long while adult culex sit parallel to the wall and the head and body are angled or hunch backed, make ringing noises in ears, have no spots on wings and the palpi are shorter in the females. 59. What are the common diseases transmitted by mosquitoes in India? A. The common diseases transmitted by mosquitoes in India are malaria (anopheles), filarial, JE and West Nile fever (Culex), Malayan filariasis and Chikungunya fever (Mansonia) and dengue, yellow fever, DHF and Chikunganya fever (Aedes).
60. What advice on chemoprophylaxis for malaria will you give to a foreigner visiting India? A. Chloroqine 300 mg once a week starting 2 weeks before arrival or latest on the day of arrival and continued for 4- weeks after leaving the country is useful if there is no resistance to chloroquine in the area to which the foreigner is traveling. Sulfadoxine – pyremathamine combination or mefloquine can also be taken if chloroqine resistance is reported. 61. What is presumptive treatment? A. This refers to treating every case of fever presuming it to be malaria and therefore it is called presumptive treatment. This consists of 600 mg (4 tablets) of chloroquine given to a febrile person without waiting for the report of the blood smear. 62. What are Fever Treatment Depots? A. These are the health facilities where personnel collect the blood smear and provide presumptive treatment to the febrile individuals. If the smear is positive, the health personnel go back and provide radical Rx. 63. What drugs and how much will you give for radical treatment of P. falciparam malaria? A. Radical treatment consists of a single dose of 600 mg chloroquine plus 45 mg of primaquine. 64. What are impregnated nets? A. These nets are used for control of malaria and are plastic nets, which are impregnated with synthetic insecticides. 65. What are the different plasmodium species causing malaria in India? A. The species in India are vivax, falciparum and malariae. 66. What is spleen rate in malaria? A. Children aged 2 – 10 years are examined for enlargement of spleen and areas are classified according to endemicty as indicated by the spleen rate : Below 10% - Non endemic 10 – 25% - Hypoendemic 25 – 40% - Endemic
40% - Hyper endemic. 67. What are the indices for blood surveys for malaria? A. The main indices are: a. Infant parasite rate: It is a good indicator of recent infection and is measured by proportion of blood smears of infants positive for malarial parasite. b. Children parasite rate: Here blood smears of children aged 2-10 years are examined. c. Annual parasite index: This is the most common index used currently. It is defined as the numberof confirmed malaria cases per 1000 persons in an area per year. d. Slide positivity rate: Proportion of slides examined which are positive for the malarial parasite. e. Slide falciparum rate: Proportion of slides examined which are positive for falciparum species. f. Annual Blood Examination Rate: The number of blood slides examined per 100 population. An ABER of 10% is warranted for good coverage of the population under surveillance. g. Monthly blood examination rate: This should be 1%during the non-transmission season and 2% during the transmission season (July – Oct) in areas under active surveillance and 15% and 20% respectively (as a proportion of new OPD cases) in passive surveillance zones. 68. What is active surveillance? A. In active surveillance, the health worker goes from house to house to search for cases of fever. One round is completed in a fortnight and the worker then repeats the visits. Thus every house is visited every fortnight. The health worker asks 4 questions: a. Is anybody suffering from fever currently? b. Did anybody suffer from fever in the pastfortnight? c. Did any guest with fever come to the house in the past fortnight? d. Did any fever case leave the area in the past fortnight? Any person complaining of fever is then given presumptive treatment after collecting a blood smear. 69. What is passive surveillance? A. In passive surveillance, any fever case reporting to a health facility is given presumptive treatment after a blood smear is made. 70. What is Annual Parasite Incidence and how is it important? A. It is defined as the number of confirmed malaria cases per 1000 persons in an area per year. It is the most sensitive index in use currently. The target for 2000 AD was an API of 0.5% which was more than 2 in 1991.
Mothers should be sensitized about all thenormal reactions so that they do not get worried. They should be told not to apply any medicine or lotion to the injection site when the crust forms or when pus is seen. They should be told to look for enlargement of regional lymph nodes, keloid formation or an abscess formation and to bring the child to the clinic if any such complications are seen.
85. What is the Tuberculin test? A. The tuberculin test is performed to screen individuals who are already infected and those who are highly susceptible to the disease. Tuberculin containing PPD (purified protein derivative) prepared from the RT strain along with Tween 80 is injected intradermally. The injection is given on the anterior side of the forearm and the result is read after 48 – 72 hours.The induration is measured and any induration greater than 10 mm is taken as positive. Strong reactors (more than 20 mm induration) have more chance of developing active TB. Similarly weak reactors (< 5 mm) also have a higher chance of infection. In countries where BCG vaccine is given at birth, tuberculin testing loses its value. 86. What is chemoprophylaxis? Gives some examples A. Chemoprphylaxis is the use of drugs to prevent onset of disease in individuals who are exposed to disease causing organisms. This can be of two types – Primary (giving drugs before a person is apparently infected) or secondary (after a person is infected but disease has not manifested). Malaria and TB are two diseases where the principles of chemoprophylaxis are put to good use. 87. What is Short Course Chemotherapy? A. Short course chemotherapy is now being widelyused in TB. A combination of 4 drugs is given for the initial period followed by 2-3 drugs during the follow up phase of 4-6 months. The total duration of most short course regimens is 6- 8 months. A number of regimens have been developed. Common ones use Rifampicin, INH,Streptomycin and Pyrazinamide for 2 months followed by Rifampicin and INH for 4-6 months. The intensive phase with four drugs rapidly converts a sputum positive person to sputum negative and therefore decreases the transmission potential of the affected individual. 88. What is DOTS? A. A major problem in tuberculosis is the lack of compliance with the recommended drugs by the patients and this leads to inadequate treatment, which further is responsible for multi drug resistance. To avoid this, under the National Programme, the patients are made to take the drugs in the presence of the health workers. This is therefore called Directly Observed Treatment Schedule (DOTS). 89. What is DOTS-Plus? A. Because of the emergence of multiple drug resistance to drugs used as the primary line of management for TB, the WHO has embarked on a programme of directly supervised regimens using drugs where no resistance has been reported. These regimens are only to be used in areas specified as suffering from MDR TB. It is also important that the secondary drugs are not used routinely and sold across the counter in such areas to avoid the emergence of resistance to these drugs. This is called DOTS Plus. 90. What is RNTCP? A. The National TB Control Programme has been revamped with the initiation of directly observed treatment regimes and an augmentation of outreach activities to increase the compliance of patients to recommended drugs. These new initiatives in the programme have resulted in the national programme now being called Revised National TB Control Programme. 91. What do you understand by defaulter action? A. A patient who does not come back for drugs for one month from the due date for medicines is called as a person lost to treatment. A postcard is sent to the patient after a week of default and the patient’s home is visited if the patient still does not come back. This is called defaulter action. With short course regimens default has decreased during the initial phase of treatment. 92. Which year did the National TB Programme start? What are the main objectives and strategies under the Programme? A. The National TB Control Program started in 1963. It aims at systematic reduction of TB in the community within the available resources of the country, within a reasonable period of time. The short-term objective of the program is to diagnose and treat patients at places nearest to their homes and also to provide preventive services, especially in the rural areas to reduce disability and death to the extent possible. The long-term objective of the programme is to reduce the problem gradually till it ceases to be a public health problem.
93. What is the prevalence rate of tuberculosis infection in India? A. The prevalence of TB infection is the percentage of individuals in the community showing positive reaction to tuberculin test. Its usefulness has decreased in recent years due to widespread BCG immunization. A third of the Indian population is infected. 94. What do you understand by Annual Infection Rate in TB? A. This is also called the incidence of infection and tuberculin conversion index. It is the proportion of persons converting from tuberculin negative to positive in a particular year. Annual infection rate in infants and children is the best indicator of transmission of infection in a community. The prevalence rate of TB disease is 4 per 1000 population while the incidence rate of disease is 1 per 1000 population. 95. How many radiologically active cases and how many sputum positive Tuberculosis cases can you expect in a population of a district with 1-2 million population? A. Each district is likely to have 20,000 radiologically active cases including 5000 sputum positive cases at any point in time. Annual incidence of new cases is expected to be 2000. 96. Who is labeled as a case of tuberculosis? A. A case of TB is an individual who is sputum positive and is therefore capable of transmitting infection. 97. What is the difference between a cases and a suspect of TB? A. A suspect is a person who is sputum negative but has radiological evidence of Tubercular shadows in the lungs. Therefore, a case is infectious while a ‘suspect’ is not infectious. 100. What is a District TB Centre? A. A district is the nerve centre for TB control activities under the NTCP. All patients are registered with the District TB Centre and drugs are provided from here. All defaulter action in addition to maintenance of the live register is the responsibility of the District TB Centre. 101. What is the danger signals signifying severe disease in Acute Respiratory Infections? A. Danger signals, which signify very severe disease, are: a. Child stops proper feeding b. Child too sleepy or difficult to wake up c. Stridor even when the child is calm. d. Wheezing e. Convulsions f. Severe malnutrition g. A very young infant who has fever or is cold to touch. 102. Name some food-borne diseases and specify measures of control for these diseases? A. Common food-borne diseases are cholera, typhoid, amoebiasis, bacillary dysentery, taeniasis, trichinellosis, trichuriasis, hydatid cyst & food poisoning 103. What is the incubation period of cholera? A. The incubation period for cholera ranges from 1 – 5 days. Most commonly it is 12 hours to 2 days. 104. How can you differentiate cholera from food poisoning?
diarrhea, vomiting and fever. The organisms most commonly multiply rapidly in animal foods like milk and milk preparations, meat, fish, eggs, ice creams, puddings, pastries, sausages and meat pies, etc. and so history of intake of such foods is elicited.
110. What are the features of botulism? A. In botulism, change of voice, diplopia, ptosis, cranial nerve palsies and obstinate constipation are observed. History of consumption of tinned food is usually observed. An incubation period of 12-36 hours is seen. Death usually occurs in 3- 7 days and mortality is high (40%). 111. Who is labeled as a convalescent carrier? A. A convalescent carrier is one who sheds infective micro-organisms during the period of convalescence. In typhoid this is for a period of 1-2 weeks after the temperature comes down. 112. Who is called a permanent carrier? A. A permanent carrier is one who continues to shed organisms forever after the disease has been cured. This is seen in typhoid where the gall bladder and kidneys are involved and bacilli are passed for a long time with interspersed periods of remission. 2.5% of typhoid cases develop into permanent carriers. 113. What is the incubation period of Typhoid? A. The commonly observed incubation period of typhoid is 10 – 14 days, but it can range from 4 – 21 days. 114. What vaccines are used for active immunization against Typhoid? A. A number of vaccines are used for active immunization against typhoid. These include: - TAB vaccine – AKD vaccine – Bivalent vaccines containing S. typhi and S. paratyphi
- Live attenuated oral vaccine (Ty 21a) TAB vaccine is the earliest vaccine developed and was introduced in 1896.Live vaccines are now routinely used and are very effective and have less side effects compared to the killed vaccines. 115. How many doses of oral typhoid vaccine are given for primary immunization? A. A single dose of oral vaccine provides long-term immunity. Booster doses should be given every 5 years. 116. When should booster of acetone killed typhoid vaccine be given? A. Booster doses should be given every 3-5 years. 117. What advice should you give to a person who is being given AKD typhoid vaccine? A. A person given AKD vaccine should not indulge in hard physical work on the day of injection as this may lead to more adverse reactions. Fever, myalgia and rash at the injection site are commonly seen. The myalgia can be debilitating and if the whole family is immunized at the same time, there may be nobody fit to cook for that night!! All these reactions are transient and go away within 24-36 hours. 118. Who is the reservoir of infection in Amoebiasis? A. Man is the reservoir of infection in Amoebiasis. 119. What is the difference in incubation period of hepatitis A and hepatitis B? A. The incubation period for hepatitis A is 15-50 days while it is 50-150 days for hepatitis B. 120. What is surface antigen and how is it useful? A. The surface antigen in hepatitis B (HBsAg) can be detected in blood for several weeks before the onset of symptoms and persists for weeks or months. Its continued presence indicates a chronic infection. 121. How is hepatitis B transmitted? How does this differ from other hepatitis causing viruses? A. Hepatitis B is transmitted through body fluids including blood and through sex where exchange of body fluids takes place. The routes of transmission can be categorized as follows:
- Parenteral or percutaneous: Through infected blood, blood products, syringes, transfusion apparatus, etc.
- Vertical or perinatal spread: Mother to infant transmission can occur when the mother is a chronic carrier or suffers from acute infection during the first trimester of pregnancy. The infection can also occur during passage through the birth canal or during the post-natal period due to close contact.
- Permucosal spread: Blood, saliva, vaginal fluids and semen are infective. 122. What is the incubation period of polio? A. The common incubation period is 7-14 days with an overall range of 3-35 days. 123. How is the prevalence of polio estimated in the community? A. The prevalence of polio in the community is assessed by conducting lameness surveys in the community among children aged 0-10 years. Lameness in children aged 0-4 years is most indicative of the current level of the problem.
124. What are the different types of vaccines available for polio? A. There are two types of vaccines available for prevention against polio – One is a killed vaccine and is injected (Salk vaccine) and the other is an live vaccine which is given orally (Sabin vaccine). The features of the two vaccines are as follows: 125. What is Pulse Polio programme? A. The pulse polio programme is an initiative for eradication of polio from all the endemic areas. Under this programe, in addition to the routine
Communicable Diseases 43
primary immunization with OPV given in early infancy, 3 doses are given to all children < 5 years of age at monthly intervals all over the country on the same days–these days are called the National Immunization days.
126. What is the Lepromin Test? A. This test detects cell mediated immunity. It simply measures the individual susceptibility or resistance. It does not indicate past or present infection. Lepromin positivity is associated with resistance to leprosy infection. After intrademal injection of 0.1 ml of lepromin antigen, two types of reactions can be seen. These are referred to as the early (Fernandez), which is read at 48 hours and the late (Mitsuda) reaction, which is read at 21 days. The early reaction comprises of redness and induration and is regarded as positive if the area of redness is greater than 10 mm at 48 hours. The late reaction consists of a papule or nodule, which is first measured after 2 weeks, and then
inadequate drug intake or development of drug resistance.
133. What is the recommended treatment for multibacillary leprosy? A. The regimen recommended by WHO consists of the following:
- Rifampicin: 600 mg once every week as a supervised dose.
- Clofazimine: 300 mg once every 4 weeks under supervision + an unsupervised dose of 50 mg daily.
- Dapsone: 100 mg unsupervised every day. Treatment s continues for a minimum of 2 years and until the smears become negative after that. 134. What are leprosy control units? A. These are established in endemic zones with a prevalence rate of 5 per 1000 and above and cover a rural population of 4-5 lakhs. There is a central leprosy clinic at the headquarters.
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135. What are SET centers under NLEP and what are their functions? A. SET stands for survey, education and training and these are the main functions of these centers. These are established in endemic zones where prevalence rate is < 5 per 1000. Leprosy paramedical workers trained in physiotherapy, health education and treatment are posted in these centers and they function under the MO in charge of the PHC. The functions of these centers are: a. Detection of early cases based on a house-tohouse survey. b. Health education c. Free treatment of all cases d. Contact tracing e. Chemoprophylaxis of contacts 136. What are STDs? A. STDs are diseases in which sex plays an important part in transmission. They include the five classical diseases–syphilis, gonorrhea, chancroid, LGV and granuloma inguinale and additional conditions like non gonococcal urtheritis, herpes progenitalis, genital warts, trichomoniasis and moniliasis. In addition, some diseases where sexual transmission is possible but not epidemiologically important are also considered as STDs. These include genital scabies, hepatitis B, genital pediculosis and genital molluscum contagisum. 137. What is contact tracing? A. Sexual partners of STDs cases (also called conjugal partners) must be located, examined and
Communicable Diseases 47
treated. This helps in arresting the transmission
of disease. This process of identifying and following up the contacts is called contact tracing.
138. What is partner notification? A. All cases of STDs are asked to name all their sexual partners from whom they could have contacted the disease or to whom they could have transmitted the disease. This process of identifying the sexual partners is called partner notification. 139. What is the incubation period of gonorrhea and how is the disease spread? A. The incubation period of gonorrhea is 2-7 days. It is primarily spread by sexual intercourse. The chance of contracting gonorrhea after a single exposure is 20-35% for men and probably double for women. 140. What is AIDS and how is it caused? A. AIDS is Acquired Immunodeficiency Syndrome and is caused by a retrovirus called Human Immunodeficiency Virus. The different routes of transmission of this communicable disease are: a. Sexual transmission – both hetero- and homosexual. b. Transfusion of infected blood c. Sharing needles and syringes by intravenous drug users. d. Transpalcental – during pregnancy e. Through breastfeeding
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141. When was the National AIDS Control Programme initiated and what activities are undertaken? A. The National AIDS Control Programme started in 1992 and has multifaceted activities. The major component activities under the program are: a. Modernizing blood banks to ensure safe blood transfusion b. IEC to increase awareness and motivate people to practice safe sex c. Sentinel surveillance d. Condom programming e. Strengthening of STD services f. Training of different categories of personnel g. Provide care and support to persons afflicted with HIV/ AIDS h. Ensuring human rights and dignity of people living with HIV/AIDS i. Operational Research j. Prevention of Mother to Child Transmission k. Identification and support to NGOs to mount targeted interventions in high risk and bridge populations. 142. Which are the high prevalence states for HIV in India? A. There are six high prevalence States in India. These are Andhra Pradesh, Maharashtra,
produce one new case of filariasis.
149. How can an epidemic of dengue fever be controlled? A. Mosquito control measures aimed at preventing breeding, killing of larvae and adults and avoiding mosquito bites is essential. The infected person should be confined to the house and kept in a mosquito net if possible to prevent transmission of infection during the first five days when the person is infective. Health education to protect themselves against mosquito bites is important. 150. What species are the primary hosts in Japanese encephalitis? A. Pigs and birds are primary hosts of Japanese encephalitis. The infection in man is a dead end infection.
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151. Why does JE spread to man? A. The major reasons which prompt the spread of JE to man are as follows: a. Relative abundance of vectors. b. Density and absolute number of infected mosquitoes. c. Adequate man-mosquito contact. d. Longevity of the vector. e. Adoption of extensive paddy cultivation f. Establishment of large modern piggeries. g. Climatic factors. h. Presence of amplifying hosts. 152. Why is JE vaccine not very useful in controlling an epidemic? A. The usefulness of JE vaccine in controlling an epidemic is limited because of the following reasons: a. Requirement of multiple doses to attain immunity. b. Time lag required for developing immunity c. Need to have 80-90% coverage of the population to control an epidemic. 153. What is the incubation period of plague? A. The incubation period of plague is 3-4 days. 154. Which form of human plague is infectious and why? A. Pneumonic plague is infectious and is responsible for man-to-man spread. Other forms of plague are only transmitted through bite of a rat flea which is infective for a few months under suitable conditions. Man-to-man transmission can
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also sometimes occur when a person comes in contact with suppurated bubos.
155. What steps should be taken to control an
epidemic of plague? A. The following steps should be followed for control of plague in man: a. Notification: Continuous surveillance of human and rat plague and its immediate notification. b. Isolation in cases of pneumonic plague. c. Suspected contacts should be quarantined for 6 days. This also applies to vessels and planes coming from plague infected areas. d. All unusual rat falls should be investigated and dead rats should be dissected for microscopic evidence of plague. e. Prompt treatment with antibiotics like streptomycin, chloramphenicol, etc. should be instituted. f. Chemoprophylaxis should be instituted for contacts. g. Adequate disinfection measures should be instituted. Safe disposal of sputum and proper boiling of patient’s clothes should be undertaken. h. Insecticidal spraying of affected areas. i. Rat burrows should be treated with DDT. j. Mass inoculation with plague vaccine. k. Health education measures. l. Information to WHO on a day-to-day basis.
156. What are the arboviral diseases seen in India? A. More than 40 arboviral diseases are seen in India. Common arboviral diseases seen in India include:
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– JE
- Dengue
- Dengue hemorrhagic fever
- Kyasunur forest disease
- Sandfly fever 157. How is epidemic typhus transmitted? A. The body louse or head louse becomes infected 3 days after sucking the blood of a typhus patient. Infection enters the human host when crushed louse or its feces are rubbed on the skin, especially over a wound or a scratch. Inhalation of louse feces or dust may account for some infections. Conjunctival transmission may also occur. 158. What is the causative organism for rabies and what is its incubation period? A. Rabies is caused by Lyssavirus type 1, a neurotropic virus belonging to the family of Rhabdoviruses. The incubation period is usually between 2-8 weeks. 159. What should you do when a patient comes with a history of a dog bite by an unknown dog? A. After being bitten by any unknown animal the following steps should be undertaken:
