Transcript Parazitológia

MEDICAL PARASITOLOGY
Laboratory diagnosis Of parasitic diseases
By
S.S Eghbali ApCp BPUMS 2008
Definitions
• Medical parasitology: the study of the parasites of
man and their medical consequences.
• Parasite: living organism requiring intimate
prolonged contact with another living organism to
meet some of its basic nutritional needs.
In a more restricted definition, it refers to organisms
that are not viruses, bacteria, fungi, rickettsia, or
chlamydia and obviously include organisms of
varying complexity from a unicellular protozoa to a
complex multicellular helminths.
• Host: organism harboring a parasite.
• Definitive host: animal harboring the adult or
sexually mature stage of the parasite.
• Intermediate host: animal in which development
occurs but in which adulthood is not reached.
• Life cycle: for survival and reproduction reasons
many parasites evolve through a number of
morphologic stages and several environments or
different hosts. The sequence of morphologic and
environmental stages is referred to as the life cycle.
• Parasitic infection: invasion by endoparasites
(protozoa and helminths).
• Parasitic disease: invasion and pathology produced by
endoparasites.
• Parasitic infestation: external parasitism by ectoparasites
(arthropods).
• Commensalisms: the association of two different species or
organism in which one is benefited and the other is neither
benefited nor harmed. (e.g. non pathogenic intestinal
protozoa)
• Reservoir host: an animal that harbors a species of parasite
that can be transmitted to and infect man.
• Vector: an arthropod or other living carrier that
transports a pathogenic organism from an infected to
a non-infected host. Carrier: a host that harbors a
parasite but exhibits no clinical signs or symptoms.
• Zoonosis: a disease involving a parasite for which
the normal host is an animal, and wherein man can
also be infected.
• Protozoa: a subkingdom consisting of unicellular
eukaryotic (Greek-karyon=nut=nucleus) animals.
• Vector: an arthropod or other living carrier that
transports a pathogenic organism from an infected to
a non-infected host. Carrier: a host that harbors a
parasite but exhibits no clinical signs or symptoms.
• Zoonosis: a disease involving a parasite for which
the normal host is an animal, and wherein man can
also be infected.
• Protozoa: a subkingdom consisting of unicellular
eukaryotic (Greek-karyon=nut=nucleus) animals.
INFORMATION EMPHASIS
• Agent ID and general importance
• Epidemiology (transmission, distribution, etc)
• Agent damage capability
• Diagnostics
• Control
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Epidemiology
Although parasitic infections occur globally,
the majority occur in tropical regions, where
there is poverty, poor sanitation and personal
hygiene
Often entire communities may be infected
with multiple, different organisms which
remain untreated because treatment is neither
accessible nor affordable
Effective prevention and control requires
"mass intervention strategies” and intense
community education. Examples include:
– General improved sanitation: pit latrines,
fresh water wells, piped water
– Vector control: insecticide impregnated
bed nets, spraying of houses with residual
insecticides, drainage, landfill
– Mass screening and drug administration
programmes which may need to be
repeated at regular intervals
The burden of some major parasitic
infections
Parasite
Plasmodium
Diseases
malaria
Soil transmitted helminths:
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Roundworm (Ascaris)
Pnemonitis, intestinal obstruction
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Whipworm (Trichuris)
Bloody diarrhoea, rectal prolapse
Hookworm (Ancylostoma and
Necator)
Coughing, wheezing, abdominal pain
and anaemia
No. people infected
Deaths/yr
273 million
1.12 million
2 billion
200,000
Schistosoma
Renal tract and intestinal disease
200 million
15,000
Filariae
Lymphatic filariasis and elephantiasis
120 million
Not fatal but 40
million
disfigured
or
incapacitat
ed
Trypanasoma cruzi
Chagas disease (cardiovascular)
13 million
14,000
African trypanosomes
African sleeping sickness
0.3 – 0.5 million
48,000
Leishamania
Cutaneous, mucocutaneous and visceral
leishmaniasis
12 million; 2 million new
cases/yr
50,000
Parasitology protozoology (protozoa),
helmintology(worms),
enthomology(insects)
• Laboratory diagnosis: - life cycle of parasits,
material v laboratory diag.
• Protozoa – intestinal, genital, urinary, blood, tissue
• Worms - Helmints:
Nematodes, Cestodes,Trematodes
• Ectoparasits: louse, ticks, flies – important as
vectors
Life cycle of parasits terminology
• Complex life cycle – key to diagnosis
• Host – hosts
• Definitive host – parasit finishes the growing cycle and is
becoming adult in it
• Not typical host - parasit cannot develop in it
• Transient host – larves are developing in it and not sexual
multiplication is performed
• Helmints : egg - larvae - adult worm
Protozoa :trophozoite - motile cysts – non motile
- sexual multiplication - zygota
- asexual- schizonts, sporogons
Diagnosis
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Problematic, not ususals outside endematic areas
Nonspecific clinical manifestation
eosinophilia in helmintoses – not constant sign
Importance of history – personal, travellers, social,
economic, food, therapy
• Conditions for successful dg:
- think on parasitosis
- také a good sample – right sample, with good method at right
time, send it in appropriate conditions to the lab that is able
to identify the parasite, good interpretation:
- Knowledge of life cycle is principal
Laboratory diagnosis
• Usually based on morphology (microscopic)
• Demonstration of the parasit in different stages of life cycle
in clinical material
• Macroscopic examination of the sample (stool or tissue)
• Microscopic examination – native smear, staining,
concentration method
• Serology – detection of antibodies, detection of antigénes
• Genetic probes - detection, identification
• Cultivation
• Animal model
Stool for parasitological examination
• Macroscopy – blood, mucous, adult worms
• Microscopy - native smear - iodine – motility, eggs
of helmints, cysts of protozoa, Rbc,Wbc
• Concentration methods – separation of cysts of
protozoa and eggs of helmints from other material in
the stool
• Staining - identification – smear of native stool +
hematoxylin eosin, trichrome
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Other material acc.to clinical
manifestation
Perianal - Enterobius vermicularis
Sigmoidoscopy - Entamoeba histolytica
Duodenal aspiration - Giardia lamblia
Biopsy of abscess of liver - Entameba histolytica
Sputum - Ascaris lumbricoides, Strongyloides,
Urine - Schistosoma Hematobium
Urogenital sample - Trichomonas
Blood - (malaria, trypanosomiasis, leishmaniosis, filariosis)
smear, thick drop - staining Giemsa, H&E,
• Serum (Hydatid cyst)
Protozoa
• Amoeba - Entamoeba histolytica, Entamoeba
coli, Naegleria fowleri, Acanthamoeba,
Endolimax nana
• Flagelata - Giardia lamblia, Trichomonas
vaginalis, Leishmania, Trypanosoma
• Ciliata - Balantidium coli
• Coccidia a Sporosoa - Cryptosporidium,
Blastocystis, Microsporidia, Plasmodia, Babesia,,
Toxoplasma
Nematodes -worms
• Enterobius vermicularis, Ascaris lumbricoides, Toxocara
canis,cati, Trichuris trichiura, Ancylostoma duodenale,
Strongyloides stercoralis, Trichinella spiralis, Wuchereria
bancrofti, Dracunculus medinensis
• Nonsegmented body, adult worms living in the GIT-e, diagnosisa: identification of eggs in the stool (morphology
of eggs)
• Filariae – tin worms parasiting in eye, skin, tissue,
transmitted by insects. Larval form- microfilariae penetrate
to blood and are transmitted by suckling insect
Cestodes • Head - scolex, segmented body
• Hermafrodit, male and female organs are present in every
segment - dif.dg. They have not GIT, absorbtion of food.
Complex life cycle with transient host (sometimes - human
– larval stage of cysticerkósis, echinococcosis)
• Taenia solium, Taenia saginata, Diphylobotrium latum,
Echinococcus granulosus, Hymenolepsis nana
Trematodes • Usually hermafrodits (ex Schistosoma)
• Need transient host
• Fasciolopsis, Clonorchis, Paragonimus, Schistosoma
Enterobius vermicularis
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Definitive host - human
transient - none
dg. – perianal sample – microscopy of eggs
fecal oral transmission - autoinfection
Enterobius vermicularis
Ascaris lumbricoides
• Definitive host: human
• Larva migrans: intestin, colon muc.membrane - blood- lung - cough mouth - colon
• dg. Egg in stool
• Infection via contaminated food
• Symptoms acc.to localisation of the larva
Ascaris lumbricoides
Toxocara canis, cati
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Definitive host dog, cat
Transient host: rat
Human incidental: human (larves)
dg. serology
transmission: hand food
Taenia saginata
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Definitive: human
transient: cattle
dg. Segments in stool
Transmission cysticercus in beef
Taenia solium
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Definitive: pig
transient: rat
incidental: human in small intestin
dg. Serology,body Rare
Contaminated food
Echinococcus granulosus
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definitive: dog
transient:sheep
incidental: human
Diagnosis: serology,Direct methods
transmission: cyste in meat
infection: mechanic pressure from expanded
cyst, prolonged growing, rupture of the cyst
and dissemination
Echinococcus granulosus
Entamoeba histolytica
• definitive: human
• Diagnosis:trophozoites in stool, serology
• dysenteria – diarhea with blood
Entamoeba
histolytica
Naegleria fowleri,
Acantamoeba,Balamuthia
• Free Living in water
• Human (via nose)
• Diagnosis:microscopy in CSF- identification of
invasive strains
Diseases:Negleriafowleri:P.A.M
Balamuthia:G.A.E,Acantamoeba:Keratitis
Toxoplasma gondii
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Definitive: cat
transient: rat
incidental: human
Diagnosis: serology , IgA, IgG, IgM
transmission: food borne, hand, annimal
disease: - intrauterine primoinfection
- generalized lymphadenopathy, encystation
in organs – abortion, eye……..
Trichomonas vaginalis
• Definitive: human
• transient: none
• dg. Cultivation - microscopy trophozoite from vagina, urine
• Sexual transmission
• Therapy of both (all) partners
Giardia lamblia
• definitive: human – small intestin,dog, cat
• transient: non
• Diag:microscopy – cysts and trophozoits in stool,
transient
in duodenal secretion
• Transmission contaminated food
• malabsorption
Giardia lamblia
Trypanosoma gambiensis
(spavá choroba)
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Definitive host: insect - fly tse tse
transient: human, monkey
dg.microscopy – thick drop
Transmission bite
Disease – sleeping disease, myalgia, arthralgia,
lymphadenopathy, hyperactivity in acute phase,
lethargy, meningoencephalitis, coma
Plasmodium-malariae, falciparum
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Definitive host:Anopheles
Transient host: human, monkey
Diag:microscopy thick drop
Transmission insect bite
disease: malaria acc.to the rate of schizogonia- clinically as
fever attacks - tercianna, quartana,
CONTROL OF PARASITIC DISEASES
A CHALLENGE FOR OUR FUTURE
COMPLEXITY OF PARASITIC DISEASES AND PROBLEMS
 The complexity of zoonotic infectious diseases offers, however,
several problems which must be solved:
 Although the general knowledge on the disease epidemiology and
transmission is usually available, the knowledge on local epidemiology
and transmission characteristics is still lacking in many cases
 Multisdisciplinary approaches and transprofessional team networks
are needed for both research and training. Efforts will be needed to
convince different ministries and health responsibles to co-work and
related political-strategic difficulties must be solved
 Funding agencies shall be convinced about the need for increasing
efforts at animal level
 Studies on geographical distribution and epidemiology of zoonoses by
using modern tools are crucial to establish the appropriate local
control measures
 Field work shall again be encouraged
 The need for “old-fashioned” disciplines as Medical Malacology and
DPUV
Entomology shall be emphasized
 THE NEED TO AGAIN EMPHASIZE THE
IMPORTANCE OF FIELD STUDIES
 Experimental work has sense if it is for the understanding of what
happens outside
 During years and years we have been developping numerous
new, modern, sophisticated molecular tools for the diagnosis of
many infectious diseases; once the new test obtained, a field trial
has been usually performed to verify its usefulness; and
afterwards, only a few or nobody is applying it in endemic areas
 Too sophisticated to be applied in many developing countries
 Too expensive and consequently unaffordable
 Too much similar tests for the same disease, so that health
responsibles become lost
 THE NEED TO AGAIN EMPHASIZE THE
IMPORTANCE OF FIELD STUDIES
 Divorce between traditional methods (as those for simple
epidemiological surveys) and new technologies
 In many centres of developing countries, health responsibles
think that traditional diagnostic methods are old fashioned and
make efforts to incorporate modern methods which are usually
more expensive, need sophisticated infrastructure and not
appropriate for large epidemiological studies in endemic areas
 The consequence is that those modern techniques are only
used in a few centres and applied to only a few patients, and
that almost nobody is carrying out surveys in the endemic
areas any more
 THE NEED TO AGAIN EMPHASIZE THE
IMPORTANCE OF FIELD STUDIES
 Consequences:
 Today, one of the greatest problems we have
is that in many areas of the developing
world we do not know which are the
epidemiological situations
 So, for given diseases we dispose of more
or less effective control methods and we
cannot apply them
 THE NEED TO AGAIN EMPHASIZE THE
IMPORTANCE OF FIELD STUDIES
 Interestingly, when we go today again to the field and
perform surveys, the results usually suggest that many
diseases are emerging / re-emerging
 Whether this is related to the higher performance of today
diagnostic methods when compared to old ones or not,
one conclusion is evident: all those diseases are still there
and continue to be as prevalent as always !
 Thus, evidence is suggesting small impact or sometimes
even no impact at all of all our efforts against neglected
infectious diseases in recent years; given diseases are
really re-emerging and/or expanding !
 TRAINING, TECHNOLOGY TRANSFER, CAPACITY BUILDING
 Control of all kind of infectious diseases needs sustainability
 Sustainibility needs specifically trained scientists in endemic
countries and areas
 Consequently, we need to include training and technology
transfer high in the agendas of research projects on zoonotic
diseases
 Problems appeared in recent years:
 There begins to be a lack of people in traditional but always
necessary disciplines for the fight against vector-borne diseases, as
Medical Entomology and Medical Malacology, or even coprological
methodology, needed for patient diagnosis in many diseases, mainly
in endemic areas of developing countries
 Molecular tools may be very helpful in attracting young researchers
to disciplines as Medical Entomology and Medical Malacology, as
well as to diagnostic methodologies as coprology
DPUV
CONTROL OF PARASITIC DISEASES
A CHALLENGE FOR OUR FUTURE
Thank you for your attention
Any Question?