emerging pathogens

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EMERGING PATHOGENS EMERGING PATHOGENS

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Page 1: Emerging pathogens

EMERGING EMERGING PATHOGENSPATHOGENS

Page 2: Emerging pathogens

DEFINITIONDEFINITION

Incidence of infection increased during last 2 Incidence of infection increased during last 2 decades or threaten to increase in near future decades or threaten to increase in near future or increase incidence of epidemic outbreakor increase incidence of epidemic outbreak e.g. e.g. Cryptosporidiosis, E.coli O157:H7, Cryptosporidiosis, E.coli O157:H7, Hantavirus, HIV, SARS, MRSA etc.Hantavirus, HIV, SARS, MRSA etc. Also Also refers to newly appearing infectious diseases refers to newly appearing infectious diseases or disease spreading to new geographical or disease spreading to new geographical area e.g. Cholera in South America, Yellow area e.g. Cholera in South America, Yellow fever in Kenya.fever in Kenya.

Page 3: Emerging pathogens

RE-EMERIGING PATHOGENS: RE-EMERIGING PATHOGENS: defdef

Diseases which are previously easily Diseases which are previously easily controlled by chemotherapy & antibiotics but controlled by chemotherapy & antibiotics but now deve antimicrobial resistance & often now deve antimicrobial resistance & often appear in epidemicsappear in epidemics

Page 4: Emerging pathogens

In 2001, a review of the scientific literature identifiedIn 2001, a review of the scientific literature identified 1415 species1415 species of infectious organisms known to be of infectious organisms known to be

pathogenic to humans, including pathogenic to humans, including 217 viruses and prions, 217 viruses and prions, 538 bacteria and rickettsiae, 538 bacteria and rickettsiae, 307 fungi, 307 fungi, 66 protozoa and 66 protozoa and 287 helminths. 287 helminths. Of these, 61% were zoonotic and 12% were Of these, 61% were zoonotic and 12% were

associated with diseases considered to be emerging.associated with diseases considered to be emerging.

Page 5: Emerging pathogens

Major etiological agents of infectious Major etiological agents of infectious diseases identified since 1972diseases identified since 1972

Year Year Agent DiseaseAgent Disease 1972 1972 Small round structured viruses Small round structured viruses Diarrhoea (caliciviruses)Diarrhoea (caliciviruses) 1973 Rotaviruses Infantile diarrhoea1973 Rotaviruses Infantile diarrhoea 1975 Astroviruses Diarrhoea1975 Astroviruses Diarrhoea 1975 Parvovirus B19 Aplastic crisis in 1975 Parvovirus B19 Aplastic crisis in chronic haemolytic anaemiachronic haemolytic anaemia 1976 1976 Cryptosporidium parvum Cryptosporidium parvum Acute Acute enterocolitisenterocolitis

Page 6: Emerging pathogens

1977 Ebola virus Ebola haemorrhagic 1977 Ebola virus Ebola haemorrhagic feverfever 1977 1977 Legionella pneumophila Legionella pneumophila Legionnaires’ diseaseLegionnaires’ disease 1977 Hantaan virus Haemorrhagic fever 1977 Hantaan virus Haemorrhagic fever with renal syndromewith renal syndrome 1977 1977 Campylobacter spp. Campylobacter spp. DiarrhoeaDiarrhoea 1980 Human T-cell lymphotropic virus-1(HTLV-1) 1980 Human T-cell lymphotropic virus-1(HTLV-1)

Adult T-cell leukaemia/ HTLV-1 associated Adult T-cell leukaemia/ HTLV-1 associated myelopathymyelopathy

1982 HTLV-2 Hairy T-cell leukaemia1982 HTLV-2 Hairy T-cell leukaemia

Page 7: Emerging pathogens

1982 1982 Borrelia burgdorferi Borrelia burgdorferi Lyme diseaseLyme disease 1983 HIV-1, HIV-2 Acquired 1983 HIV-1, HIV-2 Acquired immunodeficiency syndromeimmunodeficiency syndrome 1983 1983 Escherichia coli Escherichia coli O157:H7 O157:H7 Haemorrhagic colitis; haemolytic Haemorrhagic colitis; haemolytic uremic syndromeuremic syndrome 1983 1983 Helicobacter pylori Helicobacter pylori gastritis, gastric gastritis, gastric ulcers, increased risk of gastric cancerulcers, increased risk of gastric cancer 1988 Human herpesvirus-6 Exanthema 1988 Human herpesvirus-6 Exanthema subitumsubitum 1989 1989 Ehrlichia sppEhrlichia spp. Human ehrlichiosis. Human ehrlichiosis

Page 8: Emerging pathogens

1989 Hepatitis C virus Parenterally 1989 Hepatitis C virus Parenterally transmitted non-A, non-B hepatitistransmitted non-A, non-B hepatitis 1990 Human herpesvirus-71990 Human herpesvirus-7 1990 Hepatitis E virus Enterically 1990 Hepatitis E virus Enterically transmitted non-A, non-B hepatitistransmitted non-A, non-B hepatitis 1991 Hepatitis F virus Severe non-A, 1991 Hepatitis F virus Severe non-A, non-B hepatitisnon-B hepatitis 1992 1992 Vibrio cholerae Vibrio cholerae O139:H7 New O139:H7 New strain associated with epidemic cholerastrain associated with epidemic cholera 1992 1992 Bartonella henselae Bartonella henselae CAT-scratch CAT-scratch disease, bacillary angiomatosisdisease, bacillary angiomatosis

Page 9: Emerging pathogens

1993 Sin nombre virus Hantavirus 1993 Sin nombre virus Hantavirus pulmonary syndromepulmonary syndrome 1993 Hepatitis G virus Non A-C hepatitis1993 Hepatitis G virus Non A-C hepatitis 1994 Sabia virus Brazilian hemorrhagic 1994 Sabia virus Brazilian hemorrhagic feverfever 1994 Human herpesvirus-8 Kaposi’s 1994 Human herpesvirus-8 Kaposi’s sarcomasarcoma 1995 Hendra virus Castleman’s disease1995 Hendra virus Castleman’s disease 1996 Prion (BSE) Meningitis, encephalitis1996 Prion (BSE) Meningitis, encephalitis 1997 Influenza A virus New variant 1997 Influenza A virus New variant Creutzfeldt-Jakob diseaseCreutzfeldt-Jakob disease

Page 10: Emerging pathogens

1997 Transfusion-transmitted virus1997 Transfusion-transmitted virus 1997 Enterovirus 71 Epidemic 1997 Enterovirus 71 Epidemic

encephalitisencephalitis 1998 Nipah virus Meningitis, encephalitis1998 Nipah virus Meningitis, encephalitis 1999 Influenza A virus Influenza 1999 Influenza A virus Influenza 1999 West Nile-like virus Encephalitis 1999 West Nile-like virus Encephalitis

(New York)(New York) 2003 Corona virus (SARS)2003 Corona virus (SARS) (Most of the emerging pathogens are viruses.)(Most of the emerging pathogens are viruses.)

Page 11: Emerging pathogens

Factors responsible for emergenceFactors responsible for emergence i) increase use of antimicrobial agentsi) increase use of antimicrobial agents ii) subtherapeautic dosesii) subtherapeautic doses iii) medical practices: dialysis in renal failure, iii) medical practices: dialysis in renal failure,

multiple bl transfusions increases risk of multiple bl transfusions increases risk of hepatitis inf, HIV inf.hepatitis inf, HIV inf.

Relaxation in immunization:Relaxation in immunization: quick quick resurgence of ds e.g. diphtheria in Russia.resurgence of ds e.g. diphtheria in Russia.

New animal ds:New animal ds: Mad Cow Ds (bovine Mad Cow Ds (bovine spongiform encephalitis).spongiform encephalitis).

Page 12: Emerging pathogens

Factors responsible for Factors responsible for emergence:emergence:

Unplanned / under planned urbanization.Unplanned / under planned urbanization. Overcrowding, rapid population growth.Overcrowding, rapid population growth. Poor sanitation.Poor sanitation. Inadequate public health infrastructures.Inadequate public health infrastructures. Resistance to antibiotics.Resistance to antibiotics. Increase exposure to vectors & reservoir of Increase exposure to vectors & reservoir of

inf in nature.inf in nature. Rapid & intense international traveling.Rapid & intense international traveling.

Page 13: Emerging pathogens

WHY DO PATHOGENS WHY DO PATHOGENS EMERGE? Other factorsEMERGE? Other factors

New environmentsNew environments : : new technologiesnew technologies like like dams & irrigation systems, leads to spread of dams & irrigation systems, leads to spread of malaria, schistosomiasis, J E, AC systems: malaria, schistosomiasis, J E, AC systems: legionella inf. etc. Filtration of water, legionella inf. etc. Filtration of water, agricultural and wastewater management agricultural and wastewater management practices. practices.

sewage and sewage treatmentsewage and sewage treatment alternativesalternatives

Page 14: Emerging pathogens

Scientific advances:Scientific advances: inappropriate & inappropriate & excessive use of antibiotics & antiparasitic excessive use of antibiotics & antiparasitic drugs. ■ Improved methods of detection and drugs. ■ Improved methods of detection and analysisanalysis

■ ■ Inappropriate use of new generation Inappropriate use of new generation insecticides.insecticides.

Page 15: Emerging pathogens

Changes in human behaviour and Changes in human behaviour and vulnerability:vulnerability: Human circulation and the Human circulation and the accessibility and rapidity of transport accessibility and rapidity of transport worldwide. ■ Deliberate and accidental worldwide. ■ Deliberate and accidental release of pathogens to water. release of pathogens to water. * Individual’s level of nutrition and fitness, * Individual’s level of nutrition and fitness, stress, excessive exposure to ultraviolet stress, excessive exposure to ultraviolet irradiation, and pregnancy.irradiation, and pregnancy.

Page 16: Emerging pathogens

Demographic :Demographic : increase size of high increase size of high risk population. Overcrowding, risk population. Overcrowding, increasing population.increasing population.

Socio-economic factors:Socio-economic factors: Poor sanitation. Poor sanitation.

Page 17: Emerging pathogens

List of emerging pathogensList of emerging pathogens

Human infection:Human infection: caused by caused by bacteria, viruses, fungi & parasites. Sources bacteria, viruses, fungi & parasites. Sources

of these infections are different like water of these infections are different like water borne, inhalation, ingestion etc.borne, inhalation, ingestion etc.

Plant pathogens:Plant pathogens: may cause inf in humans. may cause inf in humans. Animal pathogens:Animal pathogens: zoonotic diseases. zoonotic diseases.

Page 18: Emerging pathogens

Bacterial infectionsBacterial infections EHEC, VTEC, O 157: H 7 EHEC, VTEC, O 157: H 7 E.coliE.coli Legionella pneumophilaLegionella pneumophila Burkholderia Burkholderia (cystic fibrosis)(cystic fibrosis) / Stenotrophomonas / Stenotrophomonas H.pyloriH.pylori Chlamydia spp.Chlamydia spp. Borrelia burgdorferi : Borrelia burgdorferi : Lyme dsLyme ds Streptococcus pyogenesStreptococcus pyogenes Mycobacteria sppMycobacteria spp BrucellaBrucella Anthrax (Anthrax (B.anthrasisB.anthrasis))

Page 19: Emerging pathogens

Staphylococcus aureus & staph epidermidis : Staphylococcus aureus & staph epidermidis : nosocomial inf.nosocomial inf.

EnterococciEnterococci Bordetella pertussisBordetella pertussis Tropheryma whippeliiTropheryma whippelii (whipple’s ds) (whipple’s ds) Compylobacter jejuniCompylobacter jejuni MycoplasmaMycoplasma Ehrlichia spp.& other rickettsial spp.Ehrlichia spp.& other rickettsial spp. Y.pestis Y.pestis (plague)(plague)

Page 20: Emerging pathogens

virusesviruses

West-Nile virusWest-Nile virus Arboviruses causing Arboviruses causing

J E, Yellow fever, J E, Yellow fever, Dengue etc.Dengue etc.

Norwalk virusNorwalk virus HIVHIV Rota VRota V

Avian flue H5:N1Avian flue H5:N1 Nipah VNipah V Influenza VInfluenza V HTLVHTLV Hanta VHanta V Hepatitis C V, E V Hepatitis C V, E V

G V.G V. Corona VCorona V

Page 21: Emerging pathogens

Fungi :Fungi : black moulds found in environment (in black moulds found in environment (in

immunocompromised person inf occurs): immunocompromised person inf occurs): a) skin infa) skin inf (warts & cauliflower like lesions). (warts & cauliflower like lesions).

Redness, swelling, discharge, pain at the inf site. Redness, swelling, discharge, pain at the inf site. b) Pneumoniab) Pneumonia most common inf. most common inf. c) Sinusitis c) Sinusitis

MOI: inhalation of spores MOI: inhalation of spores Treatment: antifungal agents, surgical excisionTreatment: antifungal agents, surgical excision No vaccine available.No vaccine available. ZygomycetesZygomycetes (eg, (eg, MucorMucor and and RhizopusRhizopus ),  ), FusariumFusarium, ,

TrichosporonTrichosporon, , PseudallescheriaPseudallescheria, and , and ScedosporiumScedosporium. .

Page 22: Emerging pathogens

Parasites:Parasites: cryptosporidium parvumcryptosporidium parvum Isospora belliIsospora belli GiardiaGiardia Malarial infMalarial inf Cyclospora spp.Cyclospora spp.

Cyclospora oocyst

Isospora oocyst

Page 23: Emerging pathogens

TRANSMISSION OF TRANSMISSION OF INFECTION (diff modes)INFECTION (diff modes)

Water borne infections:Water borne infections: includeinclude Cryptosporidium, GiardiaCryptosporidium, Giardia Legionella, Escherichia coli Legionella, Escherichia coli O157 (O157 (E. coli E. coli

O157), Cholera O139,O157), Cholera O139, rotavirus, hepatitis E virus rotavirus, hepatitis E virus norovirus (formerly Norwalk virus). norovirus (formerly Norwalk virus). Helicobacter pylori (H. pylori)Helicobacter pylori (H. pylori)

Page 24: Emerging pathogens

Corona virusCorona virus responsible for responsible for Severe Acute Respiratory SyndromeSevere Acute Respiratory Syndrome

(SARS)(SARS) : transmitted through ‘faecal : transmitted through ‘faecal droplets’.droplets’.

Mycobacterium Avium Complex Mycobacterium Avium Complex (MAC):(MAC): leading cause of death in HIV leading cause of death in HIV pts. Drinking water plays an imp role in pts. Drinking water plays an imp role in the spread of inf.the spread of inf.

Page 25: Emerging pathogens

Cyclospora cayetanensis:Cyclospora cayetanensis: outbreaks in Dec outbreaks in Dec 2000, southwest Germany, oocysts transmit 2000, southwest Germany, oocysts transmit thr’ local contact & thr’ water.thr’ local contact & thr’ water.

SchistosomiasisSchistosomiasis : : S.mansoniS.mansoni Severe illness due to dermal contact withSevere illness due to dermal contact with

toxic cyanobacteriatoxic cyanobacteria has been reported from has been reported from tropical marine bathing sites tropical marine bathing sites

Page 26: Emerging pathogens

Zoonotic infections Zoonotic infections :: Vector borne:Vector borne: A) A) MosquitoMosquito : : J E, dengue, Yellow fever, J E, dengue, Yellow fever,

chikungunya, West-Nile fever (Arboviruses).chikungunya, West-Nile fever (Arboviruses). B) B) TickTick : : KFD, Colorado tick fever, Russian KFD, Colorado tick fever, Russian

spring summer encephalitis, Rickettsial spring summer encephalitis, Rickettsial diseases: Tick typhus.diseases: Tick typhus.

Page 27: Emerging pathogens

C) C) Rat fleaRat flea : : Y.pestis,Y.pestis, Endemic typhus Endemic typhus D) D) Rat Rat :: Borrelia burgdorferi, Leptospira inf. Borrelia burgdorferi, Leptospira inf.

Lassa fever V. Lassa fever V. sewer rat:sewer rat: reservoir ofreservoir of T.gondii T.gondii Nosocomial infection:Nosocomial infection:

MRSA, Multidrug resistant MRSA, Multidrug resistant E.coli, E.coli, Ps.aeureginosa, Clostridium difficile, Ps.aeureginosa, Clostridium difficile, Serratia spp., Enterococcus Serratia spp., Enterococcus infections.infections.

Page 28: Emerging pathogens

Inhalation:Inhalation: Fungal infections: inhalation of spores (black Fungal infections: inhalation of spores (black

moulds, opportunistic fungi etc.)moulds, opportunistic fungi etc.) Influenza virus: Avian flu strain: higher Influenza virus: Avian flu strain: higher

mortality. H5N1 strain outbreak in Hong-mortality. H5N1 strain outbreak in Hong-Kong ,2008 (in birds).Kong ,2008 (in birds).

B.anthrasisB.anthrasis inf. inf.

Page 29: Emerging pathogens

Food-related diseasesFood-related diseases hepatitis E virus inf, Hep AVhepatitis E virus inf, Hep AV intestinal spirochetosis caused by intestinal spirochetosis caused by Brachyspira Brachyspira

pilosicolipilosicoli, gnathostomiasis caused by nematodes , gnathostomiasis caused by nematodes and anisakidosis caused by fish nematodes. and anisakidosis caused by fish nematodes.

non-gastric non-gastric HelicobacterHelicobacter spp., spp., Enterobacter Enterobacter sakazakiisakazakii, non-, non-jejunijejuni/coli species of /coli species of CampylobacterCampylobacter, and non-O157 Shiga toxin-, and non-O157 Shiga toxin-producing producing Escherichia coliEscherichia coli. , . , Y.enterocolitica, Y.enterocolitica, M.paratuberculosis M.paratuberculosis (Crohn's ds).(Crohn's ds).

Page 30: Emerging pathogens

Plant pathogens likely to cause inf Plant pathogens likely to cause inf in humanin human

B.cepacia found in soil responsible for rot of onion.

Erwinia amylovora, affects apples.

Cynobacterium : blue green alge.

Page 31: Emerging pathogens

Control of emerging infectious Control of emerging infectious diseasesdiseases

difficult because of the large number of disease-difficult because of the large number of disease-causing organisms that are emerging or could causing organisms that are emerging or could emerge and the great diversity of geographic areas emerge and the great diversity of geographic areas in which emergence can occur.in which emergence can occur.

Early Identification of organisms, Diagnosis & Early Identification of organisms, Diagnosis & prompt Rx:prompt Rx:

effective methodeffective method of amplifying very specific of amplifying very specific regions of an organism's genetic material by regions of an organism's genetic material by Polymerase Chain Reaction (PCR).Polymerase Chain Reaction (PCR).

Page 32: Emerging pathogens

Flow cytometeryFlow cytometery is a powerful technique is a powerful technique using laser light to quantify particles or to using laser light to quantify particles or to recognize structural features of cells. By recognize structural features of cells. By measuring the scatter and wavelength of light measuring the scatter and wavelength of light as a particle intercepts the beam, information as a particle intercepts the beam, information can be gained that allows the rapid can be gained that allows the rapid quantification of the organisms. quantification of the organisms.

Page 33: Emerging pathogens

use of use of fluorescent monoclonal antibodiesfluorescent monoclonal antibodies that are specific for a particular pathogen.that are specific for a particular pathogen.

Detection of faecal contamination of drinking Detection of faecal contamination of drinking water.water.

Control of vectors. Control of vectors.

Page 34: Emerging pathogens