EMERGING & RE-EMERGING [parasitic] INFECTIONSINIMMUNOCOMPETENT & IMMUNOCOMPROMISED HOSTS Rumala Morel Department of Parasitology Faculty of Medicine Peradeniya Year 3 2005/06 Batch
Mad cow disease H5N1 avian influenza Severe Acute Respiratory Syndrome (SARS) Ebola virus Hantavirus Monkeypox Swine flu New Diseases Emerge Old Diseases Re-emerge
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
"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 occurred in humans before or that occurred only in small numbers in isolated places. "endemic" a long term problem. Never significantly declining Eg. pneumonia
New Diseases Emerge 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 WHAT ARE EMERGING DISEASE ‘HOT SPOTS’?
Regions where new emerging infectious diseases are most likely to originate.
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
WHY EMERGE? FACTORS PREDISPOSING TO EMERGENCE 1st step Introduction of an infection for the first time into the human population 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 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
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
Emerging and Re-emerging Parasites NIAID Group 1 - Pathogens newly recognized in past two decades
Encephalitozoon cuniculi coiled polar filament, thin wall with endospore, and exospore extruded polar filament.
What is a Pandemic? ????Panic & Epidemic??? pandemic is a global disease outbreak "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
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.
Schistosomiasis ? Spreading from TROPICAL to TEMPERATE regions Due to spread of snail vector With GLOBAL WARMING
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.
Transmission ofpathogens 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 increase in the mosquito population, and suddenly you see an increase in the diseases
MALARIA WHO Global Malaria Programme aims not only to reduce
the burden of malaria in endemic areas,
but also to
Limit the geographical extent of malaria in the world.
Local Elimination the complete interruption of mosquito-borne malaria transmission in a defined geographical area
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
Control of HIV/AIDS “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 migrants and transport workers Global fund for AIDS/TB/Malaria ( GFATM) Community-based outreach strategies and new social-media tools like mobile phones, the Internet, Twitter, and Facebook
Guidelines for Preventing Opportunistic Infections Among HIV-Infected Persons --- 2002Recommendations 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.
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).
Cryptosporidium parvum: an emerging pathogen six major outbreaks in the United States - contamination of drinking water
Watery diarrhea (up to 20 liters/day) dehydration, weight loss, abdominal pain, fever, nausea and vomiting. In immunocompetent – self limited -1 to 2 wks immunocompromised chronic and severe diarrhoea Disseminated - lungs 50% infective dose (ID50) of C. parvum is only 132 oocysts for healthy persons
CRYPTOSPORDIOSIS Laboratory Diagnosis:Acid-fast staining immunofluorescence microscopy method of choice - greatest sensitivity and specificity enzyme immunoassays Molecular methods - research tool.
THE U.S. PUBLIC HEALTH SERVICEAND INFECTIONS DISEASES SOCIETY OF AMERICABOTH RECOMMEND THAT HIV-INFECTED INDIVIDUALSSHOULD NOT BRING INTO THEIR HOMES: Animals with diarrheaStray dogs or catsDogs or cats under age 6 months TREATMENT OF CRYPTOSPORIDIOSIS Paromomycin.
Acanthameoba spp. Isolated from water, soil, air conditioning etc In healthy - Acanthamoeba keratitis Immunosuppressed - Granulomatous Amebic Encephalitis (GAE) Disseminated infection
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
References “Global Trends in Emerging Infectious Diseases,” February 2008 in the journal Nature.