understanding emerging · comprehensive account of the causes of a rise in emerging and re-emerging...

Understanding Emergingand Re-emerging

Infectious Diseases

Understanding Emergingand Re-emerging

Infectious Diseases

Suparna DugalAssociate Professor,

Department of Microbiology,Sophia College, Mumbai.

Jyoti MantriAssociate Professor,

Department of Microbiology,Sophia College, Mumbai.

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First Edition : 2018

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DEDICATEDTO

OUR PARENTS

PREFACE

This book is unique in focusing on emerging and re-emerging diseases as it relates to andthreatens all the countries of the world. The problem of emerging and re-emerging diseases knowsno boundaries. Lethal microbes of all kinds can move among people and animals, from one countryto another—without notice. The problem is clearly severe in developing countries where there isovercrowding, limited drug availability and general ignorance among people. With travel encouragingthe transport of microbes, the information in this book will have wide-sweeping benefit, not only forIndia but also for the world at large. Surveillance and prevention of emerging diseases needsattention on a worldwide basis. Improving antibiotic use requires a global effort. One hopes thatbringing an organized focus to the problem will help efforts to improve knowledge and encourageresearch. It should also help in inculcating practices to reduce spread of emerging infections andprevent development of resistant ones across the globe. What is needed is a clear idea of themagnitude of the problem and what efforts can be made to address it. Our book plans to provide acomprehensive account of the causes of a rise in emerging and re-emerging diseases and proceeds todiscuss the pathogens responsible for the same. The diseases discussed include emerging and re-emerging diseases as per the World Health Organization list published in 2015 and also those mostprevalent in Asian countries. Different surveillance strategies and Government initiatives to win thebattle over these pathogens is discussed in the last chapter.

To understand the challenges posed by Emerging and re-emerging diseases a broader view ofmicrobiology is necessary, one that builds on the approaches of the past, but addresses the problemsof the present and of the future. The curriculum for microbiology keeps on changing to keep pacewith evolving microbes. Microbiology is no longer taught as a separate discipline, but is integratedwith pathology, immunology and clinical studies. However, a basic text that includes all the abovedisciplines is necessary. We hope this book gives medical and microbiology students an exciting,readable and informative insight of the threat posed by emerging and re-emerging pathogens andthe human initiatives to combat these pathogens. It is important to remember, microbes have nogeographic preference— they can cause deadly infectious diseases in countries throughout the world.

Authors

ACKNOWLEDGEMENT

We wish to acknowledge the efforts of Ms. Ayesha Shaikh for contributing thechapter on Japanese encephalitis and co-authoring the chapter on Drug resistanttuberculosis.

Authors

CONTENTS

Chapter 1 Emerging and Re-emerging Diseases — ‘Gone today, hereTomorrow?’

1 – 4

Chapter 2 Tracking the Causes — ‘Respect Existence or ExpectResistance’

5 – 12

Encroachment

Microbial Adaptation and Resistance

Human Behaviour

Changes in Agricultural Practice

Globalization

Climate Change

Wild-Life Trade

Questions for Thought and Review

PART I: DISEASES NEEDING ‘URGENT’ R&D AS PER WORLD HEALTHORGANIZATION

Chapter 3 Crimean-Congo Haemorrhagic Fever — ‘The Raging Feverfrom Crimea to Congo’

15 – 22

Structure of CCHF Virus

Transmission

Pathogenesis

Diagnosis

Prophylaxis


Chapter 4 Ebola — ‘A Bloody Death’ 23 – 30

Structure and Types of Ebola Viruses

Transmission

Symptoms

Pathogenesis

A Mystery Remains...

Diagnosis

Prophylaxis


Chapter 5 Marburg Virus Disease — ‘The MARVellously MysteriousEnemy’

31 – 38

Structure and Types of Marburg Viruses

Transmission

Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Treatment


Chapter 6 Lassa Fever — ‘The Multimammate Rat Menace’ 39 – 45

Transmission

Structure of the virus

Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Question for Thought and Review

Chapter 7 Middle East Respiratory Syndrome (MERS) -‘The Camel Flu’ 46 – 53

Structure of MERS-Corona VirusTransmissionSymptomsPathogenesisDiagnosisProphylaxisQuestions for Thought and Review

Chapter 8 Severe Acute Respiratory Syndrome (SARS) — ‘CrossingXenographic and Geographic Boundaries’.

54 – 59

Structure of the SARS Virus

Transmission and Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Treatment


Chapter 9 Nipah Virus Infection — ‘Barking Pig Syndrome’ 60 – 66

Structure of Nipah Virus (NiV)

Transmission

Symptoms

Pathogenesis

Diagnosis

Prophylaxis


Chapter 10 Rift Valley Fever — ‘The Sub-Saharan Africa Fever’ 67 – 74

The Rift Valley Virus

Transmission

Pathogenesis

Symptoms

Diagnosis

Prophylaxis


PART II: DISEASES DESIGNATED AS 'SERIOUS' BY THE WORLD HEALTHORGANIZATION

Chapter 11 Chikungunya — ‘Illness of the Bended Walker’ 77 – 81

Structure of the Virus

Symptoms

Pathogenesis

Diagnosis

Prophylaxis


Chapter 12 Severe Fever with Thrombocytopaenia Syndrome (SFTS) 82 – 86

Structure of Severe Fever with Thrombocytopenia SyndromeVirus (SFTSV)Transmission

Symptoms

Laboratory Diagnosis

Pathogenesis

Prophylaxis


Chapter 13 Zika — ‘Avoiding a Birth Defect Epidemic’ 87 – 91


Transmission

Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Zika — from India’s Perspective


PART III: EMERGING AND RE-EMERGING DISEASES — INDIAN CONTEXT

Chapter 14 Dengue — 'Break Bone Fever’ 95 – 102

Transmission


Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Treatment


Chapter 15 H1N1 (Swine Influenza) — ‘When Pigs Fly’ 103 – 110


Transmission

Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Treatment


Chapter 16 H5N1 (Avian Influenza)- ‘Creating no-Fly Zones’ 111 – 120

Transmission


Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Treatment


Chapter 17 Leptospirosis — ‘Autumn Fever’ 121 – 128

Structure of Leptospira Pathogen

Transmission

Pathogenesis

Symptoms

Diagnosis

Prophylaxis


Colour Images 129 – 136

Chapter 18 Japanese Encephalitis — ‘Fighting the Bite’ 137 – 143

Transmission


Symptoms

Pathogenesis

Diagnosis

Prophylaxis

Treatment


Chapter 19 Emergence of Drug Resistance Organisms — ‘Survival of theFittest’

144 – 153

The Discovery and Mode of Action of Antibiotics — An Overview

Mechanisms of Antimicrobial Resistance

Steps to follow to Avoid Emergence of Drug Resistant Pathogens

Examples of Drug Resistant Pathogens that have Emerged inRecent YearsQuestions for Thought and Review

Chapter 20 Drug Resistant Tuberculosis — “The Ticking Time-Bomb” 154 – 167

A Brief History of Tuberculosis

Transmission of TB

Structure and Types of Mycobacteria

Types of Tuberculosis

Symptoms

Pathogenesis

Causes of Emergence of Drug Resistance

Multi-drug Resistant Tuberculosis (MDR-TB)

Extremely Drug Resistant TB /Extensively drug-resistantTB (XDR-TB).Totally Drug Resistant Tuberculosis (TDR-TB)

Diagnosis of Drug Resistant TB

Prophylaxis of Drug Resistant TB

Treatment of Drug Resistant TB


Chapter 21 Vancomycin Resistant Enterococci (VRE) — ‘The End of theRoad for Antibiotics’

168 – 175

Structure and General Characteristics of Enterococci

TransmissionDevelopment of Vancomycin ResistanceClinical ManifestationsPathogenesisDiagnosisProphylaxisTreatmentQuestions for Thought and Review

Chapter 22 Food-Borne Illnesses — Campylobacteriosis and Listeriosis 176 – 180

Campylobacter

Listeriosis


Chapter 23 Government Initiatives and Strategies for CombatingEmerging Infections in India

181 – 185

Problems of a Developing Country

Government Initiatives

Conclusion


Chapter 24 Prions — Infectious Disease Agents of the Future 186 – 188

Bovine Spongiform Encephalopathy (BSE)

Creutzfeldt–Jakob Disease (CJD)


Chapter 25 Concluding Remarks 189 – 190

Centres and Facilities for Research/Diagnosis/Treatment of Emerging andRe-emerging Diseases

191 – 197

CHAPTER

1

ossilised remains of algae bear witness to the fact that microbes were probably the first toinhabit our planet, long before man made his first appearance [Fig. 1.1]. The remarkableability of microbes to thrive even in the harshest of conditions has made them our tiniest

and yet the strongest of adversaries. They develop strategies to invade our body and we fight them.They then change their genes, produce new variants, and challenge us to fight back using newer ways.

Photo: Pixabay

Fig. 1.1: Fossil stromatolites: formed by microbial mats. Stromatolites are layered structures formed in shallowwater by the trapping, binding and cementation of sedimentary grains by bio films of microorganisms, especially

cyanobacteria. They include some of the most ancient records of life on Earth.

Dr. Joshua Lederberg has rightly said, “The future of humanity and microbes will likely unfold asepisodes of a suspense thriller that could be titled Our Wits versus Their Genes.” We can never adaptthrough our own genes as quickly as they can - so we must use our wits to find other ways.

In the beginning of the last century, we started developing drugs to vanquish our age-oldenemies- tuberculosis, plague, leprosy and smallpox. However, eliminating these old scourges did notmean our battle with these tiny life forms had succeeded, for new diseases arose. As the Hydrain Greek mythology whose one head if cut off, could give rise to two new ones, newer illnesses beganto emerge.

F

Emerging andRe-emerging Diseases-

‘Gone Today, hereTomorrow?’

Understanding Emerging and Re-emerging Infectious Diseases2

In recent years, India has reported a dramatic entry of diseases that were not witnessed earlier.Are these new diseases? Or had they gone previously undetected simply due to our poor understandingand lack of suitable diagnostic techniques? Did these diseases arise due to the rapidly changinglifestyle and globalization of our country? Moreover, do they herald a frightening new scenario wherein we have met our true nemesis?

This alarming trend of emerging and re-emerging diseases is seen not only in India but has alsobeen reported across the world. Cases of AIDS, multiple drug resistant TB, and Ebola have bought thisdisturbing trend to the forefront.

In the 1980s, when HIV made its first appearance, it was unfathomable that a virus could cripplethe very system responsible for protecting the human body, leaving it defenceless against a myriad ofalien microbial attacks. Communities of vibrant and healthy people were lost to AIDS-a syndrome thatwas never seen nor heard of before. As new diseases began to emerge, people found that bacteria andviruses had acquired a novel property – of being able to cross species. Today a large number of newdiseases are zoonotic in origin, that is, they are of animal origin and have crossed the species barrier toinfect humans.

BOX 1.1

The Human Immunodeficiency Virus (HIV)

BOX 1.1

INTERESTING FACTS

In 1999, an International team of researchers reported that they had discovered the origins of HIV-1,the predominant strain of HIV, in the developed world. According to the AIDS Institute, a sub-speciesof chimpanzees native to West equatorial Africa were the original source. It is thought that HIV-1 wasintroduced into human population when hunters became exposed to infected blood.

Photos: Pixabay

Emerging and Re-emerging Diseases- ‘Gone today, here Tomorrow?’ 3

One of the best examples of this is the avian influenza virus that has its origins in the countrysideof China. Here poultry farming and pig farming are done in the same cramped areas, which provide anideal environment for the influenza viruses to breed, mutate, acquire deadly new forms and crossspecies. Another form of emergence is the development of a more virulent and resistant variety of thesame microbe, which we had earlier encountered and thought to have conquered. A classic example ofthis is MDR-Tuberculosis and XDR-Tuberculosis that are the most deadly form of tuberculosis toemerge.

With global travel, the emergence of diseases in parts of the world that were hitherto unaffectedis also rampant. To cite an example, Ebola- a disease restricted to African regions has now beendisseminated in various parts of the world.

So how would one define an emerging disease? Moreover, what are re-emerging diseases? Well,simply put, emerging infectious diseases are those new diseases that have never been recognizedbefore, like severe acute respiratory syndrome (SARS) and H5N1 infection. Over thirty new infectiousagents have been detected worldwide in the last three decades; sixty per cent of these are of zoonoticorigin, and more than two-thirds of these have originated in wildlife. Re-emerging diseases are thosethat have been around for decades or centuries, but have come back in a different form (usually aresistant one) or in a different geographical location. Examples of these diseases include, ebolahaemorrhagic fever, marburg haemorrhagic fever, multiple drug resistant tuberculosis and vancomycinresistant enterococcal infections.

A meeting of a panel of scientists and public health experts was convened by the World HealthOrganization (WHO) in Geneva on 10th December 2015 to prioritize the top five to ten emergingpathogens likely to cause severe outbreaks in the near future, and for which few or no medicalcountermeasures exist. These diseases provide the basis for work on the WHO blueprint for researchand development (R&D) and preparedness to help control potential future outbreaks.

The initial list of disease priorities needing ‘urgent’ R&D attention comprised Crimean CongoHemorrhagic Fever, Ebola Virus Disease and Marburg, Lassa Fever, MERS and SARS corona virusdiseases, Nipah and Rift Valley fever. The list is to be reviewed annually or when new diseases emerge.

Three other diseases were designated as 'serious', requiring action by the WHO to promote R&D assoon as possible; these were chikungunya, severe fever with thrombocytopaenia syndrome, and Zika.

Emerging infectious diseases account for 26 per cent of annual deaths worldwide. Nearly 30 percent of 1.49 billion disability-adjusted life years (DALYs) are lost every year to diseases of infectiousorigin. The most affected by these infectious diseases are those people who live in the developingcountries like India. Poor sanitation, contaminated food, inadequate personal hygiene, or access to safewater and lack of basic health services- conditions common to large parts of India are to be blamed forthis.

In India, the most important diseases which have made their appearance lately and left a markinclude dengue, chikungunya, swine influenza, avian influenza, leptospirosis, Japanese encephalitis,vancomycin resistant enterococci and drug resistant tuberculosis. We shall discuss these diseases indetail in the following chapters.

Understanding Emerging and Re-emerging Infectious Diseases4

References IJMR 2013 July Emerging and re-emerging infections in India: An overview.

Taylor L.H., Latham S.M, Woolhouse M.E. Risk factors for 3 human disease emergence. Philos TransR Soc Lond B Biol Sci 2001; 356 : 983-9.

World Health Organization, Regional Office for South East 4. Asia Region. Combating emerginginfectious diseases in the South-East Asia Region. New Delhi: World Health Organization, WHOSEARO; 2005.

Myers G., MacInnes K., and Korber B. The emergence of simian/human immunodeficiencyviruses. AIDS Res Hum Retroviruses. 1992;8:373–86.

Allan J.S., Short M. and Taylor M.E. Species-specific diversity among simian immunodeficiencyviruses from African green monkeys. J Virol. 1991;65:2816–28.

Gao F., Yue L., White A.T., Human infection by genetically diverse SIVSM-related HIV-2 in WestAfrica. Nature. 1992;358:495–9.

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