emerging & re emerging diseases

42
EMERGING & RE-EMERGING [parasitic] INFECTIONS IN IMMUNOCOMPETENT & IMMUNOCOMPROMISED HOSTS Rumala Morel Department of Parasitology Faculty of Medicine Peradeniya Year 3 2005/06 Batch

Upload: yapa

Post on 11-May-2015

10.699 views

Category:

Health & Medicine


1 download

DESCRIPTION

Lecture given to 3rd year medical students.

TRANSCRIPT

Page 1: Emerging & re emerging diseases

EMERGING & RE-EMERGING [parasitic] INFECTIONSINIMMUNOCOMPETENT & IMMUNOCOMPROMISED HOSTS

Rumala MorelDepartment of Parasitology

Faculty of MedicinePeradeniya

Year 3 2005/06 Batch

Page 2: Emerging & re emerging diseases

• Mad cow disease• H5N1 avian influenza• Severe Acute Respiratory Syndrome

(SARS) • Ebola virus• Hantavirus• Monkeypox• Swine flu

New Diseases EmergeOld Diseases Re-emerge

Page 3: Emerging & re emerging diseases

Objectives

• Define emerging & re-emerging infections• List the emerging & re-emerging parasitic

infections which are important globally & in SL• Briefly describe the factors which predispose to

emergence & re-emergence of infections in immunocompetent & immunocompromised hosts

• Recognize the current handicaps when dealing with the risks of these infections

• Briefly describe the preventive aspects of these infections

Page 4: Emerging & re emerging diseases

"emerging," "re-emerging," or "endemic"

Re-emerging = diseases that once were major

health problems globally or in a particular country, and then declined dramatically, but are again becoming health problems for a significant proportion of the population.

• Diseases thought to be adequately controlled making a “comeback” are “re-emerging”

Emerging = diseases that have not occurredin humans before orthat occurred onlyin small numbersin isolated places.

"endemic" a long term problem.Never significantly decliningEg. pneumonia

Page 5: Emerging & re emerging diseases

• Emerging diseases = new infections that arise from changes in existing organisms

or • known infections that spread to new geographic

areas or populations• Incidence of such a disease in people increases

over 20 years or threatens to increase

New Diseases Emerge

WHAT ARE EMERGING DISEASE ‘HOT SPOTS’?Regions where new emerging infectious diseases

are most likely to originate. Usually tropical – developing countries ill equipped to cope

Page 6: Emerging & re emerging diseases

Old Diseases Re-Emerge(A) EVOLUTION OF THE INFECTIOUS AGENT• Mutations in bacterial genes that confer

resistance to antibiotics – 20% • Multidrug-resistant & extremely drug-resistant TB • Multi drug resistant P.falciparum

(B) REDUCED HUMAN IMMUNITY• Immunization failure

(breakdowns in public health measures)a greater proportion of susceptible individuals in a population and an increased reservoir of the infectious agent.

• Increased number of immunocompromised hosts - due to the stress of famine, war,

or disease

Page 7: Emerging & re emerging diseases

ZOONOSES In most cases (60%) that’s an infection that’s already out there in nature – may be a virus that’s naturally infecting some other species.

Ecological changes - puts humans in contact with the virus. Usually due to human activities

WHY EMERGE? FACTORS PREDISPOSING TO EMERGENCE

1st step Introduction of an infection for the first time into the

human population

Page 8: Emerging & re emerging diseases

WHY EMERGE? FACTORS PREDISPOSING TO EMERGENCE

• ENVIRONMENTAL CHANGE tropical forests are cleared to make way for new roads, displacing disease-carrying animals and insects and increased human traffic through previously isolated areas

• URBANIZATION - person-to-person transmission • POOR PRIMARY HEALTH CARE

public health services may not be equipped to deal with some infectious outbreaks

Page 9: Emerging & re emerging diseases

Globally important Emerging & Re-emerging Infectious Diseases

RE-EMERGINGtuberculosismalariaschistosomiasis

EMERGINGAIDS cholera CJDEbola hemorrhagic

feverinfluenzaLegionnaire disease Lyme disease

Page 10: Emerging & re emerging diseases

List of NIAID* Emerging and Re-emerging Diseases

– Group I—Pathogens Newly Recognized in the Past Two Decades

– Group II—Re-emerging Pathogens– Group III—Agents with Bioterrorism Potential

• NIAID—Category A • NIAID—Category B • NIAID—Category C

* NIAID = National Institute of Allergy & Infectious Diseases - USA

Page 11: Emerging & re emerging diseases

NIAID Group 3 -Category B

Food & Waterborne pathogens

Cryptosporidium parvum

Cyclospora cayatanensis

Giardia lamblia Entamoeba

histolytica Toxoplasma gondii

Emerging and Re-emerging Parasites

NIAID Group 1 - Pathogens newly recognized in past two decadesAcanthamoebaMicrosporidia

Encephalitozoon cuniculiEncephalitozoon hellemEnterocytozoon bieneusi

Page 12: Emerging & re emerging diseases

Encephalitozoon cuniculi

extruded polar filament.

coiled polar filament, thin wall with endospore,and exospore

Page 13: Emerging & re emerging diseases

What is a Pandemic?

• "The world is now at the start of the 2009 influenza pandemic 30,000 confirmed cases from 74 countries” 11th June 2009

• WHO increases pandemic alert level to phase 6 "community level outbreaks in at least one other country in a different WHO region in addition to the criteria defined in Phase 5.

• " Phase 5 is characterized by human-to-human transmission of the virus into at least 2 countries in 1 WHO region.

• H1N1 immunization campaign

????Panic & Epidemic???

pandemic is a global disease outbreak

Page 14: Emerging & re emerging diseases
Page 15: Emerging & re emerging diseases

Global Warming

• A temperature change of several degrees may make temperate zones more hospitable to vectors of tropical diseases

• Malaria, Dengue - mosquitoes• Schistosomiasis – snails

• At the same time, tropical areas may become less hospitable to some of the same diseases.

Page 16: Emerging & re emerging diseases
Page 17: Emerging & re emerging diseases

Schistosomiasis

? Spreading fromTROPICAL toTEMPERATE regionsDue to spread of snail vectorWith GLOBAL WARMING

Page 18: Emerging & re emerging diseases

crayfish as a biocontrol agent for the snail vector of human schistosomiasis, a disease that has resurfaced as a growing problem due to China's rapid land-use change.

Page 19: Emerging & re emerging diseases

Transmission of pathogens with reduced

dependence on host mobility

• water-borne –diarrhoeal agents• attendant-borne [eg. Escherichia coli]

Emerging hospital-acquired pathogens• Humans create pathways for transmission

eg. spreading HIV through needle sharing, blood transfusion, commercial sex trade. It is now pandemic in spite of its relatively inefficient transmission.

• mosquito-transmitted diseases: water is the limiting step. So irrigation projects, building of dams, cause an increasein the mosquito population, and suddenly you see anincrease in the diseases

Page 20: Emerging & re emerging diseases

MALARIA• WHO Global Malaria

Programme aims not only to reducethe burden of

malaria in endemic areas,

but also to Limit the

geographical extent of malaria in the world.

Local Elimination the complete interruptionof mosquito-borne malaria transmission in adefined geographical area

Page 21: Emerging & re emerging diseases

Key interventions to control malaria include:• prompt and effective

treatment with artemisinin-based combination therapies; • use of insecticidal nets by

people at risk; And• indoor residual spraying to control the vector mosquitoes.

Page 22: Emerging & re emerging diseases

Emerging Parasitic Diseases in Sri Lanka

• Leishmaniasis• Cryptosporidiosis• Dirofilariasis• Toxocariasis• Cutaneous Larva Migrans

Page 23: Emerging & re emerging diseases

Promastigotes Amastigotes

Sand fly

Cutaneous leishmaniasis is established

Visceral leishmaniasis is

Emerging in Sri Lanka

Page 24: Emerging & re emerging diseases

Cutaneous leishmaniasis in Sri Lanka

Page 25: Emerging & re emerging diseases
Page 26: Emerging & re emerging diseases
Page 27: Emerging & re emerging diseases

Quick Look at Current HIV Statistics in SL as of End March 2009

Quick Look at Current HIV Statistics in SL as of End March 2009

HIV IN SL – March 2009HIV : 1099AIDS :   293AIDS Deaths :   189

Children living with HIV     :     37

Since 1981, HIV/AIDS has infected 60 million & killed half of them.2 million die every year & every 15 seconds a person is infected with HIV

Page 28: Emerging & re emerging diseases

“test and treat” strategy of universal, voluntary, annual HIV testing and immediate treatment for those who test positive.

High-risk populations In SL CSWs, Drug users, Internal migrantsand transport workers Global fund for AIDS/TB/Malaria ( GFATM)

Community-based outreachstrategies and new social-mediatools like mobile phones,the Internet, Twitter, and Facebook

Control of HIV/AIDS

Page 29: Emerging & re emerging diseases

Guidelines for Preventing Opportunistic Infections Among HIV-Infected Persons --- 2002

Recommendations of the U.S. Public Health Service and the Infectious Diseases Society of America*

(A) preventing first episodes of disease by chemoprophylaxis or vaccination (primary prophylaxis), and preventing disease recurrence (secondary prophylaxis).

(B) PREVENTING EXPOSURE TO PATHOGENS• oral-anal contact - to reduce the risk for intestinal

infections e.g., cryptosporidiosis, shigellosis, campylobacteriosis, amebiasis, giardiasis, and hepatitis

• contact with animals - cryptosporidiosis, toxoplasmosis, salmonellosis, campylobacteriosis, or Bartonella infection.

Page 30: Emerging & re emerging diseases

HIV infected - PREVENTING EXPOSURE TO PATHOGENS (contd)

• New pet – avoid animals aged <6 months or <1 year for cats –toxoplasmosis,cryptosporidiosis, Bartonella infection (avoid cat bite/scratches, flea control), salmonellosis, and campylobacteriosis

• Poultry and meat are safest when adequate cooking is confirmed with a thermometer (internal temperature of 180ºF for poultry and 165ºF for red meats). no trace of pink

• Uncooked meats should not be allowed to come in contact with other foods; hands, cutting boards, counters, and knives and other utensils should be washed thoroughly after contact with uncooked foods (BIII).

Page 31: Emerging & re emerging diseases

Cryptosporidium parvum: an emerging pathogen

six major outbreaks in the United States - contamination of drinking waterhighly environmentally resistant cyst of C. parvum survives drinking water filtrations chlorination

oocysts do not survive cooking

2 types of oocyststhick-walled - excreted thin-walled -autoinfection

Page 32: Emerging & re emerging diseases

Cryptosporidium

Page 33: Emerging & re emerging diseases

• Watery diarrhea (up to 20 liters/day)

• dehydration, weight loss, abdominal pain, fever, nausea and vomiting. 

• In immunocompetent – self limited -1 to 2 wks

• immunocompromisedchronic and severe diarrhoeaDisseminated - lungs

feco-oralwater contaminated by livestock mammal feces HIGH RISK GROUPSinfants and younger children

in day-care centers -frequent diaper-changing

those whose drinking water is unfiltered and untreated

Farmers / veterinarians

TRANSMISSION CLINICAL FEATURES

50% infective dose (ID50) of C. parvum is only 132 oocysts for healthy persons

Page 34: Emerging & re emerging diseases

CRYPTOSPORDIOSIS

• Laboratory Diagnosis:Acid-fast staining

• immunofluorescence microscopy

method of choice - greatest sensitivity and specificity

• enzyme immunoassays• Molecular methods - research tool.

Page 35: Emerging & re emerging diseases

TREATMENT OF CRYPTOSPORIDIOSISParomomycin.

THE U.S. PUBLIC HEALTH SERVICEAND INFECTIONS DISEASES SOCIETY OF AMERICA

BOTH RECOMMEND THAT HIV-INFECTED INDIVIDUALSSHOULD NOT BRING INTO THEIR HOMES:

Animals with diarrheaStray dogs or cats

Dogs or cats under age 6 months

Page 36: Emerging & re emerging diseases

Cyclospora cayetanensis

Page 37: Emerging & re emerging diseases

Life Cycle

of

Cyclospora

cayetanensis

Page 38: Emerging & re emerging diseases

Acanthameoba spp.

In healthy -Acanthamoeba keratitis Immunosuppressed -

Granulomatous Amebic Encephalitis (GAE) Disseminated infection

Isolated from water, soil, air conditioning etc

Page 39: Emerging & re emerging diseases

Emerging & Re-emerging Infectious Diseases Surveillance & Control

• Disease surveillance is concentrated not in developing countries, where emerging diseases are most likely to arise, but in developed countries that can afford laboratories

• Global disease surveillance networks(1) U.S. Defense Department’s GEIS (2) WHO - Global Outbreak Alert and Response Network (GOARN)

• Identify, confirm and respond to outbreaks of international importance.

Emerging Pathogens Institute -prevent or contain new and re-emerging diseases

Page 40: Emerging & re emerging diseases

References

• “Global Trends in Emerging Infectious Diseases,” February 2008 in the journal Nature.

Page 41: Emerging & re emerging diseases

SGD questions

Page 42: Emerging & re emerging diseases