Introduction & Historical Perspective Infectious Diseases Prof. Muhammad Akram Hossain MMC 12/24/2013 1 Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Introduction & Historical Perspective Infectious Diseases
Prof. Muhammad Akram HossainMMC
12/24/2013 1Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Infection is different…….(from other medical and
pathology disciplines)…..pathology disciplines)…..
…….it spreads!
12/24/2013 2Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Infectious Diseases as a groupremain the most common cause ofdeath globallydeath globally
The history and the great successes of public health have been in infectious disease prevention and control
12/24/2013 3Prof. Muhammad Akram Hossain, Infectious disease- Introduction
1969
“Infectious disease have been conquered”
William Stewart
Surgeon General, USA
12/24/2013 4Prof. Muhammad Akram Hossain, Infectious disease- Introduction
World Disaster Report 2000
International Federation ofRed Cross/Red Crescent
INFECTIOUS DISEASE IS INFECTIOUS DISEASE IS BIGGEST KILLER
13 million deaths in 1999100,000 deaths from natural disasters12/24/2013 5Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
Frequency & ImpactCauses of Death 1998 (WHO)
12/24/2013 6Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Disability Adjusted Life Years Lost, WHO 1998
12/24/2013 7Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Communicable Disease: Impact by Wealth
Mortality due to Infectious diseases
Morbidity (DALY’s lost)
World’s poorest 20%
59% 64%
• Even in the U.S., deaths due to all infections increased 1980-1992 to #3 cause (after CV disease and malignancy)
World’s richest 20%
8% 11%
World total 34% 44%
12/24/2013 8Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Rank of Infectious Diseases Cause of Death millions %
Pneumonia (all bugs) 3.745 7.2
Tuberculosis 2.910 5.6
Diarrheal diseases (all bugs) 2.455 4.7
HIV 2.300 4.4HIV 2.300 4.4
Malaria (falciparum) 1.5-2.7 2.9-5.2
Measles .960 1.8
Hepatitis B .605 1.2
Pertussis .410 0.812/24/2013 9Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
Deaths from infectious diseases
• Every year - 5.5 crores die• Infectious diseases - 1.73 crores (31%)• Cardivascular diseases -1.70 crores (30%)
• others -• Among the infectious diseases• Among the infectious diseases
�Resp tract infections - 40 lakh ( 95% from LRTI)�HIV/AIDS - 26 lakh�GIT infections - 22 lakh�Tuberculosis - 16 lakhs
So more than 50% die from RTI & GIT infections
12/24/2013 10Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Historical Impact of Infectious Diseases: Epidemics
• Plagues described in biblical & early history—disease entity usually unclear
• Athens 430-29 BC killed ¼ of land army• Athens 430-29 BC killed ¼ of land army• Rome 165-70 (Antonine plague) ¼-1/3
population mortality
12/24/2013 11Prof. Muhammad Akram Hossain, Infectious disease- Introduction
The Black Death
• 542, Roman empire:Justinian plague• 1331 plague started in China• Travelled to Middle East via trade routes• 1346 plague introduced at the siege of• 1346 plague introduced at the siege of
Caffa (Crimea), � Europe by ship• Frequent recurrences: last in England
1665, in the Mediterranean 1721• 1894 epidemic in Hong Kong dispersed
to all major ports within 10 years
12/24/2013 12Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Plague: impact
• Mortality in Europe 1346-50 est. 33%• European population continued to decline
until mid 1400’s• Population of China halved 1200-1393• Contributed to anti-Semitic outbursts, possibly • Contributed to anti-Semitic outbursts, possibly
undermining of religious authority.• May have contributed to decline of serfdom &
other social changes• Most recent outbreak in India 1994, widely
endemic in rural rodents
12/24/2013 13Prof. Muhammad Akram Hossain, Infectious disease- Introduction
The Cholera Pandemics• 1st Pandemic started Calcutta 1817• 13% population mortality Cairo 1831• “millions”of deaths world wide 19th century.• Global dissemination enabled by global sea
transport• Generated a high level of fear• Cholera epidemics an important factor in the
establishment of boards of health and thedevelopment of urban sanitation
• Recent return to South America after acentury of absence
• Remains endemic in S. Asia, recurrentlyepidemic in Africa
12/24/2013 14Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Recent EpidemicsPolio• A disease of good hygiene• 50 years later, approaching global eradication
HIV• Most important epidemic since the Black Death
InfluenzaInfluenza• Annual epidemics since ?• 20 million deaths in 1918• Pandemic expected any time
West Nile VirusSARS12/24/2013 15Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
12/24/2013 16Prof. Muhammad Akram Hossain, Infectious disease- Introduction
12/24/2013 17Prof. Muhammad Akram Hossain, Infectious disease- Introduction
ID’s in Battles & Wars • “And typhus, with its brothers and sisters,--plague,
cholera, typhoid, dysentery,--has decided more campaigns than Caesar, Hannibal, Napoleon….Zinsser
• Typhus & dysentery along with other factors, decimated Napoleon’s troops in Russia
• Distribution of smallpox-infected blankets to Indians, Lord Amherst 1763Lord Amherst 1763
Crimean War: 1854-56_______________wounded died of
woundssick died of
disease
French 39,869 20,356 196,430 49,815
English 18,283 4,947 144,390 17,225
Russian 92,381 37,958 322,097 37,45412/24/2013 18Prof. Muhammad Akram Hossain, Infectious disease- Introduction
New infections - since 1975
• HIV• vCJD• Hepatitis C, E
• Legionella• Campylobacter• C. difficile• Hepatitis C, E
• HTLV; HHV6, 7, 8 • Lassa, Ebola• Nipah; Hendra• Hantavirus (SN)• Avian flu• SARS
• C. difficile• Helicobacter pylori• E. coli O157• Vibrio cholerae
O139• Cryptosporidium• Chlamydia12/24/2013 19Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
Re-emerging and resurgent
• Tuberculosis• Dengue• Malaria• Malaria• Cholera• West Nile virus• Yellow fever
12/24/2013 20Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Modern medicine
• Healthcare associated infection– invasive procedures– immunocompromised/immunosuppressed– bed pressures, throughput– bed pressures, throughput– staff shortage
• Antimicrobial resistance– MRSA– ESBL– MDR TB
12/24/2013 21Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Modern lifestyle
• Travel• Trade• Fast food• Fast food• Childcare• Elderly care• Sexual freedom• Prosperity…………………and poverty12/24/2013 22Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
Principle of diagnosis Lab Dx of Microbialdiseases
• Demonstration of causative agents by microscopy commonly practiced for parasitic diseases & fungal diseases
• Isolation and identification of causative agent by artificial culture - (C/S) commonly by artificial culture - (C/S) commonly practiced for bacterial diseases.
• Detection of antibody or antigen from blood or other body fluids practiced for viral diseases & some bacterial & parasitic diseases
• Detection of Nucleic acid segment (DNA or RNA)12/24/2013 23Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
• Specimen : according to site of infection
• Microscopic Examination :• Light microscopy / DGM / FM / EM
– Unstained preparation– stained smear -Gram, AFB, Fluorescence
• Isolation & identification : Bacteriological, fungal,
Steps involved in Lab Dx of Microbial diseases
• Isolation & identification : Bacteriological, fungal, protozoal Culture, Cell culture for viruses– Identification by standard biochemical & serological test
• Immunological test : detection of Ag or Ab by LAT, ELISA etc
• Detection of gene: NA based techniques by PCR etc
• Special tests : Toxigenicity tests12/24/2013 24Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
Formula for Lab Dx of Parasitic diseases
• Almost all parasitic diseases can be diagnosed by M/E examination of appropriate specimen and finding some structure of the parasites.
• Specimen: depends on site of infection • Specimen: depends on site of infection • Blood, stool, HVS, BM, etc
• Protozoal structure • Cyst, trophozoite, Oocyst, special - LD bodies, schizont
etc
• Metazoal structure • Ova, larva, segments
12/24/2013 25Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Examples of Lab Dx of Parasitic diseases by M/E
• Amoebiasis – By M/E of stool for Cyst or trophozoite, Liver aspirate for
trophozoite
• Giardiasis – By M/E of stool for Cyst or trophozoite
• Trichomoniasis – By M/E of vaginal discharge for trophozoite
• Malaria– By M/E of PBF for schizont, merozoite, gametocytes etc
(MP)
• Kala-azar– By M/E of BM, Spleen or LN for LD bodies
• Cryptosporidiasis– By M/E of ZN stained smear of stool for Oocyst12/24/2013 26Prof. Muhammad Akram Hossain,
Infectious disease- Introduction
Principle of Lab Dx of bacterial diseases
Diagnosis of bacterial disease is based ondemonstration of the causative agents byM/E, then isolation & identification of byculture, and detection of Antibody or antigenculture, and detection of Antibody or antigenby immunological tests. In special cases othertests like toxigenicity tests, detection of genesby NA based techniques are used.
12/24/2013 27Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Steps of Lab Dx of bacterial diseases
– Specimen : According to site of infection (Sputum blood, stool, urine, swab etc)
– M/E : Stained (G S/ Z-N/ Albert) or unstained preparation or DGM or IFM
– Isolation & identification (Culture): media, – Isolation & identification (Culture): media, incubation time, temp & environment should be mentioned -
– Immunological tests : ICT, ELISA, Latex agglutination, Co-agglutination for detection of Ab or Ag.
– NA based techniques : PCR
12/24/2013 28Prof. Muhammad Akram Hossain, Infectious disease- Introduction
Principle: Virtually all viral diseases are diagnosed by serological testsfor antibody against the virus. In few cases antigens are also detected. IgMindicates recent infection and if facilities not available rising titer for IgGis also helpful. Electron Microscopy is also done in reference lab. Cellculture is done for research purpose. NA based techniques are used inspecial cases.Steps:
Lab Dx of Viral diseases
Steps:Specimen : Mostly serum other specimens according to site ofinfection.M/E : Light microscopy is rarely helpful, E/M can be done whereavailable.Isolation in cell culture : done for research purpose.Immunological tests: mostly for Ab e.g. Anti HAV, AntiHCV, Anti Dengue, Anti rubella etc.
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