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

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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

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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

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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

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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

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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

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Modern medicine

• Healthcare associated infection– invasive procedures– immunocompromised/immunosuppressed– bed pressures, throughput– bed pressures, throughput– staff shortage

• Antimicrobial resistance– MRSA– ESBL– MDR TB

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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

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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.

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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

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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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