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Communicable diseases hha_2012w.2

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  • 1. Communicable Diseases in humanitarian settings 1
  • 2. “communicable” diseasesInfectious diseases that can be transmitted from one individual to another either directly by contact or indirectly by fomites and vectors. 2
  • 3. Communicable diseasesFood- and Zoonoses and vector borne Air-borne diseaseswater-borne diseases • Brucellosis • Legionellosis Cholera • Echinococcosis • Meningococcal disease Hepatitis Botulism • Rabies • Pneumococcal infections Campylobacteriosis • Malaria • Tuberculosis Cryptosporidiosis • Plague • Viral haemorrhagic fevers Giardiasis Sexually transmitted diseases Diseases preventable by E.coli vaccination • Chlamydia infections Leptospirosis • Gonococcal infections • Diphtheria Listeriosis Salmonellosis • HIV-infection • Haemophilus influenza Shigellosis • Syphilis • Measles Toxoplasmosis Viral hepatitis • Mumps Trichinosis • Pertussis • Hepatitis A Yersinosis • Hepatitis B • Poliomyelitis • Hepatitis C • Rubella
  • 4. WHO 2004: Low income countries leading mortality causes Neonatal infections Malaria Lower respiratory infections Tuberculosis Chronicobstructivepulmonary disease Diarrhoeal diseasesCoronary heart disease HIV/AIDS Stroke and other Prematurity and cerebrovascular low birth weight diseases 4
  • 5. MDG 6Combat HIV/AIDS, Malaria and Other Diseases• targets – 1. Halt and begin to reverse, by 2015, the spread of HIV/AIDS – 2. Achieve, by 2010, universal access to treatment for HIV/AIDS for all those who need it – 3. Halt and begin to reverse, by 2015, the incidence of malaria and other major diseases 5
  • 6. HIV and crises• How do crises affect HIV? 6
  • 7. 1. Communicable disease cycle Death Progression Healthy of disease State Immunity Clinical Risk factors Illness Exposure factors Biological Susceptibility to evidence of infection infection 7
  • 8. Communicable diseases Population Vulnerability Individual susceptibility Risk exposure Individual physical and material resources Immunity to pathogens Health care services 8
  • 9. Higher incidenceCrises Higher mortality Malnutrition Absence / Poor Communicable Disruption Hygiene Diseases of health Wat/San care Poor Living Conditions Epidemics 9
  • 10. Effects of outbreaks on health system1. Population panic2. Overcrowding of Health Services I. Overwork of Health Staff II. Health Staff at exposed risk III. Risk to patients3. Malfunction of Health Services4. Increased morbidity I. Further spread of outbreaks5. Increased mortality6. Economic and social consequences 10
  • 11. 2. What can be done? Treatment Surveillance Death Progression of Healthy disease StateContainment Immunity Clinical Risk factors Illness Exposure factors Prevention Biological Susceptibility to evidence of infection infection 11
  • 12. Rapid assessment Surveillance SurveyOften qualitative or quantitative data quantitative datasemi-quantitative datawide variety of data limited data Can gather wide variety of datadata on convenience Often tries to gather data on Usually gathers data onsample of people and every case of illness sample of populationfacilitiesdata at a single point in data over ongoing, data at single point intime prospective time period timegathers data for Gathers data for numerator Gathers data fornumerator of prevalence of incidence and prevalence numerator andand incidence; ; Denominator must come denominator, allowingDenominator must come from separate source. calculation offrom separate source prevalence or incidence rates
  • 13. surveillance• Systematic ongoing collection, collation, and analysis of data and the timely dissemination of information to those who need to know so that action can be taken. » World Health Organization• The ongoing systematic collection, analysis, and interpretation of health data, essential to the planning, implementation, and evaluation of public health practice, closely integrated with the timely dissemination of these data to those who need to know. » US Centers for Disease Control and Prevention
  • 14. Surveillance• Passive Surveillance – uses available data or reporting from health care provider or regional health officer• Active Surveillance – periodic field visits to health care facilities to identify new cases 14
  • 15. 15
  • 16. Prevention• Public level – Vector control – Water and sanitation systems – Blood safety requirements• Individual level – Hand washing – Condoms• Public / Individual level – Vaccination • Routine or during outbreaks 16
  • 17. Control measures• Prevention of exposure: – Isolation, vector control, containment – Hygiene and education• Prevention of infection: – Vaccination, clean water• Prevention of disease: – prophylaxis• Prevention of death: – Case identification and management 17
  • 18. Surveillance in emergencies• Objectives – identify public health priorities; – monitor the severity of an emergency by collecting and analyzing mortality and morbidity data; – detect outbreaks and monitor response; – monitor trends in incidence and case-fatality from major diseases; – monitor the impact of specific health interventions – provide information for programme planning, implementation and adaptation, and resource mobilization.DATA ➜ INFORMATION ➜ ACTION 18
  • 19. Disease Early Warning System (DEWS) Pakistan• Covered 92 districts and ~ 60% of the population.• centralized in Islamabad, with regional hubs and surveillance officers active at district level.• Weekly reporting includes priority epidemic diseases and those with high morbidity & flood related diseases.• Data sources include up to 2600 basic health units and all large government hospitals,• Data relayed using a variety of media, SMS, fax, and telephone.• Widespread compliance, due in part to the regular visits of the surveillance officers to facilities. 19
  • 20. Disease Early Warning System (DEWS) Pakistan• quantity of weekly data reported places very high work burden on the surveillance officers, many of whom cover wide geographical areas.• A lot of data but… – 90% of outbreaks have been detected by formal immediate alerts. – Only 10% were detected through data analysis.• incompatibilities with other “vertical” surveillance systems• Not transitioning to integration into routine government surveillance systems 20
  • 21. DEWS- Film• http://www.youtube.com/watch?v=s2Q5oQx4 dGw&feature=bf_prev&list=ULQRFpUxJxcoE&l f=mfu_in_order 21
  • 22. True or False• The geographical distribution of reported cases is indicative of where the disease is the worst.• The case fatality rate data from health facilities is indicative of how deadly a disease is• In a complex emergency where systems are disrupted it is important for the emergency surveillance system to capture as much information as possible• HIV, TB and Malaria get a lot of attention and money from global initiatives so it is not appropriate to spend humanitarian funds 22
  • 23. Key information for designing surveillance systems• What is the population under surveillance – displaced population, local population etc• What data should be collected and why• Who will provide the data• What is the period of time of the data collection?• How will the data be transferred (data flow)?• Who will analyse the data and how often?• How will reports be disseminated and how often? 23
  • 24. Questions to ask when selecting diseases /conditions• Does the condition result in a high disease impact (morbidity, disability, mortality)?• Does it have a significant epidemic potential (e.g. cholera, meningitis, measles)?• Is it a specific target of a national, regional or international control programme? (e.g.malaria, TB)• Will the information to be collected lead to significant and cost-effective public health action? 24
  • 25. Key diseases to consider• bloody diarrhea,• acute watery diarrhea,• suspected cholera,• lower respiratory tract infection,• measles,• meningitis.• Other endemic /epidemic prone diseases (eg malaria or viral haemorrhagic fevers) 25
  • 26. Risk factors• Diarrheal diseases – Overcrowding – Inadequate quantity and/or quality of water – Poor personal hygiene – Poor washing facilities – Poor sanitation – Insufficient soap – Inadequate cooking facilities 26
  • 27. Risk factors• Acute respiratory infections – Inadequate shelter with poor ventilation – Indoor cooking, poor health care services – Malnutrition, overcrowding – Age group under 1 year old – Large numbers of elderly – Cold weather 27
  • 28. Risk factors• Meningococcal meningitis – Meningitis belt (although the pattern is changing to include eastern, southern & central Africa) – Dry season – Dust storms – Overcrowding – High rates of acute respiratory infections 28
  • 29. Risk factors• Malaria – Movement of people from endemic into malaria-free zones or from areas of low endemicity to hyperendemic areas – Interruption of vector control measures – Increased population density promoting mosquito bites – Stagnant water – Inadequate health care services – Flooding – Changes in weather patterns 29
  • 30. Risk factors• Measles – Measles vaccination coverage rates below 80% in country of origin, overcrowding, – population displacement• Tuberculosis – High HIV seroprevalence rates – Overcrowding – Malnutrition 30
  • 31. Key terms• Incidence – the number of new cases of a specified disease reported over a given period. – number of new cases per 1000 people• Case-fatality rate (CFR) – the percentage of persons diagnosed as having a specified disease who die as a result of that disease within a given period, – usually expressed as a percentage (cases per 100).• Attack rate (outbreaks): – The cumulative incidence of cases (persons meeting case definition since onset of outbreak) in a group observed over a period during an outbreak.• Epidemic threshold: – level of disease above which an urgent response is required – specific to each disease depending on infectiousness, other determinants of transmission and local endemicity levels. 31
  • 32. Epidemic threshold• Diseases for which one suspected case represents a potential outbreak and requires immediate investigation: – cholera – measles – typhus – plague – yellow fever – viral haemorrhagic fever 32
  • 33. Case classification• Suspected case – Clinical signs and symptoms compatible with the disease in question but no laboratory evidence of infection (negative, pending or not possible)• Probable case – Compatible clinical signs and symptoms, and additional epidemiological (e.g.contact with a confirmed case) or laboratory (e.g. screening test) evidence for the disease in question• Confirmed case – Definite laboratory evidence of current or recent infection, whether or not clinical signs or symptoms are or have been present – Even if clinical symptoms are not -subclinical infection is a major source of transmission 33
  • 34. Case definitions• developed for each health event /disease /syndrome. – Use MoH or WHO definitions• For consistency of reporting• Used for surveillance not treatment 34
  • 35. Case definition: ACUTE WATERY DIARRHEAThree or more abnormally loose orfluid stools in the past 24 hours with orwithout dehydration.• suspect case of cholera: – Person aged over 5 years with severe dehydration or death from acute watery diarrhea with or without vomiting. – Person aged over 2 years with acute watery diarrhea in an area where there is a cholera outbreak.• To confirm case of cholera: – Isolation of Vibrio cholera O1 or O139 from diarrheal stool sample. 35
  • 36. Case definition: MEASLESFever and maculopapular rash (i.e. non-vesicular) and cough, coryza (i.e. runny nose) orconjunctivitis (i.e. red eyes)orAny person in whom a clinical health workersuspects measles infection.• To confirm case: – At least a fourfold increase in antibody titre or – isolation of measles virus or – presence of measles-specific IgM antibodies.. 36
  • 37. 37
  • 38. Scenario: early detection & response 38
  • 39. Scenario: delayed detection & response 39
  • 40. 40
  • 41. Zimbabwe CholeraWeekly attack rates, by district. Weekly attack rates, by district.as of 31/01/09 W4 as of 14/03/09 W11 41
  • 42. Global system• CDC – International Emergency and Refugee Health Branch• European CDC• WHO – DCE (disease control in humanitarian emergencies) • Part of Global Alert and Response department • Produce “public health risk assessment” for crises – GOARN (global alert and response network) http://video.who.int/streaming/eprfilms/GOARN_Wor king_Together_in_Outbreak_Response.wmv – Event management system 42
  • 43. WHO SHOC(strategic health operations center) 43
  • 44. International Health Regulations• Legally binding international treaty – 194 signatory countries – entered into force on 15 June 2007,• Purpose: enable international community to prevent and respond to acute public health risks – potential to cross borders and threaten people worldwide• requires countries to report certain disease outbreaks and public health events to WHO.• requires countries to strengthen their existing capacities for public health surveillance and response. 44
  • 45. Humanitarian Crises and IHR (2005)Potential for serious public health impact:“The population at risk is especiallyvulnerable (refugees, low level ofimmunization, children, elderly, lowimmunity, undernourished, etc.)”“Concomitant factors that may hinder ordelay the public health response (naturalcatastrophes, armed conflicts,unfavourable weather conditions, multiplefoci in the State Party).”
  • 46. Humanitarian Crises and IHR (2005)Risk of international spread:“Event in an area of intenseinternational traffic with limitedcapacity for sanitary control orenvironmental detection ordecontamination.”

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