Communicable Disease Life & Health Course # 001278 Naresuan University Thailand

1. Jabu Munalula M.D.
Life Science Course
Narasuan University

2.  What is a communicable disease
 Burden of communicable disease
 Causes of communicable disease
 Prevention and control of communicable disease

3.  Can be transmitted from
 Also called, infectious, transmittable
 Spread by infectious agent (pathogens)
 bacteria, viruses, parasites

4.  Not causes by infectious agents
 Not transmissable from person to person
 They may be inheritable genetically
 Examples
 Hypertension, diabetes, heart disease

5.  Infection: invasion of a host by a (micro)organism
 Endemic: stable number of cases over time , stable
disease population
 Ex: Dengue fever is endemic to Thailand
 Epidemic: sudden transient rise in disease population
 Ex: AIDS is an epidemic in Thailand
 Pandemic: worldwide epidemic affecting human
populations across large regions
 Reemerging diseases:
 Ex: TB, malaria, cholera

6.  The Black Death (plague): started in 14th century,
killed 75 million people
 Cholera: killed tens of millions during the 19th century,
remains a public health concern
 Influenza
 Measles
 Smallpox
 Malaria
 AIDS

7.  Diarrheal diseases
 Symptoms: diarrhea, abdominal pain
 Ex: cholera
 Respiratory diseases
 Symptoms: shortness of breath, cough
 Ex: pneumonia
 Febrile illness
 Symptom: fever
 Ex: Malaria

8.  Waterborne: contaminated water
 Ex: cholera
 Foodborne: contaminated food
 Ex: salmonella
 Airborne: transmitted through air
 Ex: TB
 Vector-borne: vectors like mosquitos or rats
 Ex: malaria

13. Direct Indirect
 Physial contact  Air bourne
 Sexual contact  Vector-borne
 Biting  Vehicle-borne
 Direct projection of
droplets
 Across placenta

14.  Human/animal reservoirs = infected host
 Examples
 Animals: dogs / rabies vrus
 Improperly handled food: raw fish/ Opisthorchis viverrini
 Enviornmental reservoirs

15.  Respiratory tract: breathed in through lungs
 Ex: Mycobacterium Tuberculosis
 Gastrointestinal tract: enter through the mouth
 Ex: diarrheal diseases
 Skin: breaks in skin integrity
 Ex: malaria parasite after mosquito bite

16.  Not every exposure results in disease
 Susceptible hosts develop the disease after exposure
 Factors that increase susceptibility: Risk factors
 Poor or no immunity
 Lack of vaccination
 Poor nutrition
 Coexistent disease

17. • Events that occur from time of exposure to final outcome
without intervention
• Exposure:
• Infection
• Disease
• Outcome
• Can apply specific targeted interventions to
prevent/control

18.  Susceptible host contacts
infectious agent
 Agent has not yet
entered the body
 Ex,
 Hand shake
 Drinking contaninated
water

19.  Infectious agent enters
the body
 Starts to multiply
 Clinical manifestations
of the disease appear
 Signs
 symptoms

20.  Clinical manifestations are present
 Incubation period from infection to onset of clinical
manifestations
 Not all infected hosts develop disease
 Carriers: infected but no clinical manifestations
 Active cases: have clinical manifestations
 Acute infection: rapid onset, short duration of illness
 Chronic infection: prolonged duration of illness

21.  Recovery
 Ex: Common cold
 Chronic illness
 Ex: Syphillis
 Disability
 Ex: elephantitis, polymyelitis
 Death

22.  Single celled free living prokaryote
 Can be found anywhere and everywhere
 Produce chemical toxins that cause disease
 Divide rapidly under the right conditions
 Aerobic: require oxygen
 Anaerobic: do not require oxygen
 Move by air and water
 Can live on many surfaces
 Skin, clothes, hair, furniture

23.  Non-living microscopic particles
 Consist of fragments of DNA or RNA
 No cells
 Do not need to feed
 Attack health living cells
 Take over host cell functions to make more virus
particles

24.  Usually enter the body through mouth or skin
 Include protozoa (single celled) and helminths
(worms)
 Tape worm, liver flukes, loa loa
 Can lead to liver disease, blindness, heart disease

25.  Rapid growth worldwide population
 Globalization
 By 2015, 90 % of population growth will be in
developing countries
 Lack resources to support rapid growth
 Feeding more people requires changes in food
production and distribution
 Unsanitary conditions

26.  Shift from rural to urban area
 More people live in urban are than rural area
 Concentrated populations
 Overcrowding
 Close proximity
 Poor sanitation
 Poverty
 Poor education

27.  Cross-border migration
 Political and economic refugees
 Thailand: 2 million immigrants, 150 000 refugees from
neighbor countries
 Poor access to health facilities
 No preventive or primary care services
 Unsanitary living conditions

28.  Water and sanitations systems
 Improving in urban area
 Improve management of diarrheal diseases
 Due to rapid population growth, + 20 million people
in urban SEAR still with unsanitary water supply

29.  Unregulated cross border livestock trade
 Unhealthy livestock rearing practices
 Current production methods
 Increase risk of H1N1
 Small scale vs industrialized poultry farming
 Biosecurity investment
 Increased poultry density
 Single species cultivation

30.  HIV/AIDS
 Tuberculosis
 Malaria
 Respiratory diseases
 SARS
 Influenza
 Malaria
 Diarrheal diseases
SEAR: South East Asia Region

31.  Viral infection
 Affects mammals and birds
 Common symptoms
 Chills, fever, body pain, soar throat, weakness
 Transmitted through air
 Cough or sneeze
 Also direct contact with bird dropping/secretions
 Can be killed by sunlight, detergent, disinfectant

33.  Global seasonal epidemics
 250,000-500,000 deaths annually
 Major influenza pandemics in 20th century
 H5N1 (2009): avian flu (Asia)
 Influenza A H1N1 (2009): swine/avian flu (N. America)
 Vaccination available for specific strains
 Not widely available
 Usually in developed countries
 Usually to high risk populations

34.  Bird flu: primarily a bird illness
 few reports of direct human to human transmission
 Main risk factor: handling infected poultry
 Quite lethal: 60% of known infection die
 Currently the most concerning pandemic threat
 High reservoir population
 Highly virulent
 Significant mutation rate
 High mortality

36.  Most common cause of influenza in 2009
 Endemic in some human populations
 Caused 17000 deaths by 2010
 Less virulent than H5N1
 Combination of avian, pig, human
genes

39.  Viral respiratory disease in humans
 Hong Kong, 2009 epidemic
 8422 cases, 900 deaths
 10% fatality
 Spread to 37 countries in a few weeks
 Did not reach pandemic proportions

41.  Most deadly infectious disease
 Soon will be overtaken by AIDS
 Caused by bacteria, Mycobacterium tuberculosis
 Spread through the air from infected cough/sneeze
 Classic symptoms:
 Chronic cough, blood tinged sputum, fever, night
sweats, weight loss
 One third of global population infected with TB
bacteria
 1 new infection every second

43.  Globally : 33 million people living with HIV
 0.8% of adult population
 2.6 million newly infected in 2009
 Most new infecting in developing countries
 New cases decreased 16% from 2001-2009
 Women account for 51% of people living with HIV
 SEAR: 3.5 million people living with HIV
 India, Indonesia, Myanmar, Nepal, Thailand

44.  Retrovirus
 Attacks immune system
 Acquired immunodefiencey syndrome AIDS
 Opportunistic diseases
 Pnemocystis carinii
 Cryptosporidium
 Cervical dyspasia/cervical cancer
 Kaposis sarcoma

45.  Transmission
 Sexual intercouse
 MSM
 Prostitution
 Unprotected sex
 Intravenous drug use
 Placenta (mother child transmission)
 Medical procedure (rare)

46. HIV: How fast can it spread?
• San Francisco gay men 0-50% in +/- 5
years
• Edinburgh IVDU 0-50% in 3 years
• Nairobi prostitutes 0-85% in 6 years
• Chiangmai (Thailand) prostitutes--
incidence 10% per month
• Harare (Zimbabwe) young adults--.2%–
20% in 5 years

47.  Treatment
 No cure yet
 Anti-retroviral therapy
 ART (anti retroviral therapy)
 HIV is becoming a chronic disease
 Less people dying of opportunistic diseases

48.  Impact:
 > 2 billion people at risk
 +/- 300 million cases/yr
 +/- 2 million deaths/yr., mainly African kids
 Biology:
 Vector-borne (Anopheles mosquito)
 Gradually acquired, incomplete immunity

50.  Bednets, especially when insecticide-treated
 Early diagnosis & treatment requires access to
functioning lab, effective drugs
 Domiciliary spraying
 Control of larval breeding
 Environmental, chemical, biological
 Chemoprophylaxis of selected groups
 Vaccine: not yet

51.  # 2 cause of death in under 5’s in LIC’s (cholera
and others can cause epidemic diarrhea in
adults)
 Multiple organisms
 Rotavirus and other viruses, various types of E.
coli, Salmonella, Shigella, Campylobacter, giardia, cr
yptosporidia, ? helminths etc.
 Different types/patterns of diarrhea:
 acute watery, dysentery, chronic
 Main mechanism of death, esp. in acute watery
dd
 Dehydration
 Risks:
 unsafe drinking water, poor sanitation, unavailable
washing water, malnutrition, not breast
feeding, probably HIV, traditional treatment
practices, and misuse of medication

52.  Prevention:
 Better drinking water, better sanitation, more
washing water, food safety, hygiene, breast feeding &
food safety, immunization
 ??rotavirus vaccine
 Management
 Oral rehydration with appropriate fluid (cereal-
based ORS probably better)
 Continued breast (or other feeding if weaned)
 Avoid dangerous traditional practices (withholding
oral intake, purges etc.)
 Train health workers that ORS, not medicines, is the
treatment (except for dysentery).

53.  TB
 Malaria
 STD
 Syphilis
 gonorrhea

54.  Interventions applied before disease occurrence
 Protect individual and community
 Vaccination: vaccine preventable diseases
 Influenza
 Tentanus
 Measles
 Strep pnuemonia
 mennigitis

55.  Applied to reduce severity of disease after it has
occurred
 Include public health and education measures
 Improves health care
 Transmission control