1. MEDICAL PARASITOLOGY Laboratory diagnosis Of parasitic diseases By
S.S Eghbali ApCp BPUMS 2008

2. 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.

3. 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).

4. 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.

5. 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.

6. 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.

7. INFORMATION EMPHASIS
Agent ID and general importance
Epidemiology (transmission, distribution, etc)
Agent damage capability
Diagnostics
Control

8. 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

9. The burden of some major parasitic infections
Parasite
Diseases
No. people infected
Deaths/yr
Plasmodium
malaria
273 million
1.12 million
Soil transmitted helminths:
Roundworm (Ascaris)
Whipworm (Trichuris)
Hookworm (Ancylostoma and Necator)
Pnemonitis, intestinal obstruction
Bloody diarrhoea, rectal prolapse
Coughing, wheezing, abdominal pain and anaemia
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 incapacitated
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

10. 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

11. 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

12. Diagnosis 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

13. 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

14. 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

15. 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)

16. 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

17. 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

18. 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

19. Trematodes - Usually hermafrodits (ex Schistosoma) Need transient host
Fasciolopsis, Clonorchis, Paragonimus, Schistosoma

20. Enterobius vermicularis
Definitive host - human
transient - none
dg. – perianal sample – microscopy of eggs
fecal oral transmission - autoinfection

21. Enterobius vermicularis

22. 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

23. Ascaris lumbricoides

24. Toxocara canis, cati Definitive host dog, cat Transient host: rat
Human incidental: human (larves)
dg. serology
transmission: hand food

25. Taenia saginata Definitive: human transient: cattle
dg. Segments in stool
Transmission cysticercus in beef

26. Taenia solium Definitive: pig transient: rat
incidental: human in small intestin
dg. Serology,body Rare
Contaminated food

28. Echinococcus granulosus
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

29. Echinococcus granulosus

30. Entamoeba histolytica
definitive: human
Diagnosis:trophozoites in stool, serology
dysenteria – diarhea with blood

31. Entamoeba histolytica

33. 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

36. Toxoplasma gondii 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……..

38. Trichomonas vaginalis
Definitive: human
transient: none
dg. Cultivation - microscopy trophozoite - from vagina, urine
Sexual transmission
Therapy of both (all) partners

40. 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

41. Giardia lamblia

42. Trypanosoma gambiensis (spavá choroba)
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

44. Plasmodium-malariae, falciparum
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,

48. CONTROL OF PARASITIC DISEASES
A CHALLENGE FOR OUR FUTURE
PUV

49. 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 Entomology shall be emphasized
DPUV

50. 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
DPUV
Too much similar tests for the same disease, so that health responsibles become lost

51. 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
DPUV

52. 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 D
PUV

53. 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 !
PUVD

54. 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

55. CONTROL OF PARASITIC DISEASES
A CHALLENGE FOR OUR FUTURE
PUV

56. Thank you for your attention
Any Question?