Lecture Notes in Parasitology

LECTURE NOTES IN PARASITOLOGY Prepared by: Jasmen S. Pasia, RMT, MSMT MLS Department, San Pedro College Parasitology Types of Parasite:

is the area of biology concerned with the __________________ of one living organism on another.

1. According to its habitat Ectoparasite

Medical Parasitology is concerned with the animal parasites of humans and their medical significance, as well as their importance in human communities.

- lives on the outside of the host (______________) Endoparasite

_________ is a branch of medicine which deals with tropical diseases and other special medical problems of tropical regions.

- lives within the body of the host (_____________) 2. According to its relationship with the host Obligate

A tropical disease is an illness, which is indigenous to or endemic in a tropical area. Many tropical diseases are ______________________.

- when they take up ______________ in and are completely dependent upon the host (Ascaris lumbricoides)

Biological Relationships

Facultative

Symbiosis

- they are capable of leading both a ____________ ______________ existence even if they are outside the body of the host (Strongyloides stercoralis).

___________________________________ Commensalism - is a symbiotic relationship in which two species live together and one species benefits from the relationship ____________________________

Intermittent - visit the host only during feeding time (_______________)

_______________________________.

Incidental

Mutualism

- establishes itself in a host in which it __________ ordinarily live ( Trichinella spiralis).

- is a symbiosis in which two organisms _____________ from each other Parasitism

Permanent

- is a symbiotic relationship where one organism, the parasite lives in or on another for its __________________________ of the host.

- remains on or in the body of the host from early life until maturity, sometimes for its entire life cycle (______________________)

Parasitism Pseudoparasite Parasite - __________ mistaken as parasites (pollen, hairs) - organisms which ____________ of another organism for growth and survival

Types of Hosts:

Host

Definitive host

- ________________ that harbors the parasite and is usually larger than the parasite

- harbors the _____________________________ stages of the parasite (humans). Intermediate host - harbors the _____________________________ of the parasite (snails). 1

= undergo further development in _____________ to reach their infective stage. Ex: Taenia solium – pork Taenia saginata - beef

Paratenic Host - a host which act as a __________________ for the parasite and in which the parasite does not _____________________ (prawns).

5. Contact Transmitted = parasite is really __________________ = parasite does not have to go further development Ex: Trichomonas ________________ ________________ vermicularis 6. Animal-borne = animal to human = zooanthroponosis

Reservoir - a host in which the parasite is __________________ and act as a source of ___________ for new cases (rodents). Incidental Host

7. Airborne Ex: Enterobius vermicularis Ascaris lumbricoides

- refers to a situation in which the _______________ is not necessary for the parasite _______________________ (trichinosis).

8. Autoinfection = infecting one’s self (_______________________)

Nomenclature

Portals of Entry

Classified according to the International Code of _______________________

1. Mouth (Oral Cavity) A) ingestion of: embryonated eggs ( __________________) ___________ (Entamoeba histolytica) B) intimate oral contact Trichomonas ________________ Entamoeba _________________

Each parasite belongs to a Phylum, Class, Order, Family, Genus, and Species At times the further divisions of Suborder, Superfamily, Subfamily, and Subspecies are employed Family Name - ___________________ Superfamily - ___________________ Subfamily - ___________________

2. Skin A) Active penetration: filariform larvae (__________________) cercariae (Schistosomes)

Names are binomial for species and trinomial for subspecies Names are in latin or Latinized.

3. Others A) Sexual Contact Trichomonas ____________ B) Transplacental _________________ gondii C) Transmammary Strongyloides stercoralis D) Intranasal Naegleria ______________ Acanthamoeba __________

Modes of Transmission 1. Soil-transmitted = undergo ______________________ to reach the infective stage Ex: Ascaris lumbricoides Trichuris trichiura 2. Snail-transmitted = undergo further development in the ___________ to reach their infective stage. Ex: Schistosoma japonicum

Portals of Exit 1. Stool = ________________________

3. Arthropod Transmitted = undergo further development in _______________ to reach their infective stage Ex: malaria – _______________ filariasis - _______________ leishmaniasis – sandfly trypanosomiasis A. American – reduviid bug B. African - tse-tse flies

2. Urine = T. vaginalis, S. haematobium 3. Sputum = Paragonimus ________________ 4. Blood = microfilaria (_____________) Gametocytes (_____________)

4. Food-Animal Transmitted

5. Tissue Biopsy 2

a) muscle Trichinella spiralis (_____________) Taenia solium (cysticercus cellulosae) Diphyllobothrium latum (______________)

PARASITOLOGY

HELMITHS

b) rectal biopsy amoebiasis secondary Schistosoma infection

PHYLUM PLATYHELMINTHES

Epidemiologic Measures

Class Cestoda

Epidemiology = is the study of patterns, _____________, and occurrence of disease

PROTOZOA

ARTHROPODS

PHYLUM NEMATODA

Class Trematoda

Phylum Nematoda

1) Incidence = is the number of _______________ of infection appearing in a population in a given period of time

General Characteristics Females ________ than males and have a ________ tail. Males have ___________ tail with spicules for _________________. Unsegmented Round elongated worms measuring from a few mm to meter in length Complete digestive tract (mouth to anus) ___________ circulatory system Found in the intestine, blood, and tissue Worldwide _______________ There are sensory organs

2) Prevalence = is the number (______________________) of individuals in a population estimated to be infected with a particular parasite species at a given time 3) Cumulative Prevalence = is the percentage of individuals in a population infected with at least one parasite 4) Intensity of Infection = refers to the ______________ per infected person = this may be measured directly or indirectly and is also called as the _________________

Aphasmids Trichinella spiralis Trichuris trichiura Capillaria philippinensis Phasmids Ascaris lumbricoides Strongyloides stercoralis Hookworms Enterobius vermicularis Filarial worms Habitat Small Intestine Ascaris lumbricoides Strongyloides stercoralis Hookworms Capillaria philippinensis Trichinella spiralis

5) Morbidity = clinical consequences of _________________ that affect an individual’s well-being 6) Mortality = incidence of ____________ in a given population Parasitic Infection and Disease The transmission of parasites involved 3 factors: a) source ____________ b) mode of __________________________ c) _________________ of susceptible host

Large Intestine Trichuris trichiura Enterobius vermicularis

A human being, when infected by a parasite may serve as: a) its only ______________ b) its principal host with ____________ also infected c) its ______________ host with 1 or other animals as principal host

3

Tissue Nematodes Trichinella spiralis Wuchereria bancrofti Brugia malayi Onchocerca volvulus Loa loa Dirofilaria immitis Gnathostoma spinigerum

Has a single uterus which contains ________________.

Larva Migrans in Man Dracunculus medinensis Angiostrongylus cantonensis Ancylostoma caninum Ancylostoma braziliense

Trichinella spiralis Also known as the ______________, “Pork Worm” Diseases: - Trichinosis - ________________ - Trichinelliasis Morphology: Male Worm Measures _______ in length by 40-60 micra in transverse diameter. Cloaca is found at the caudal end which is evertible during coitus. It is guarded by 2 conspicuous _______ which clasp the female during copulation. Spicule is ______________. Posterior end of the worm is curved ventrad.

Encysted Larva measures __________ micra when extruded by the female worm provided with a ___________ burrowing tip at its tapering anterior end in the striated muscles, the larva grows to about 0.8-1mm and becomes encrusted along the axis of the muscle fibers

Life Cycle Infective Stage - _____________ larva Definitive Host - ______________ - man (accidetnal host) Diagnostic Stage - encysted larva

Female Worm About 3-4 mm long and 60-80 micra in width. Vulva opens at the __________ of the body.

4

Diagnosis - Muscle Biopsy - Bentonite _______________ Test

Ova: characteristically _________________ with bipolar unstained intralaminar prominences which have the appearance of mucoid plugs measures ________ micra by 22-23 micra in addition to a vitellaine membrane, it has a triple shell consisting of chorionic layer, albuminous layer and the bile-stained layer

Clinical Disease 1. Destruction of the muscle fiber. 2. Eosinophilia 3. May have ____________ involvement Prevention and Control 1. Sterilizing garbage containing ____________ scraps. 2. Cook meat properly (77oC or 170oF). 3. Storage at -150C for 20 days or -300C for 6 days. 4. Screening of _____________. 5. Public Education.

Life Cycle Infective Stage - _______________ egg Definitive Host - humans Diagnostic Stage - ________ (unsegmented) No _________________ phase Resides in the ____________ intestine No intermediate host needed

Treatment: 1. Thiabendazole 2. Mebendazole

Trichuris trichiura Also known as the “_______________” Diseases: - Trichuriasis - _____________ Infection Morphology: Male Worm: Measures 3 - 3.5 cm. A single lanceolate spicule protrudes through a refractile penial sheath which has a bulbous termination covered with ___________________________. Distinguished from the female by its coiled caudal extremity about 360 degrees or more. Female Worm: Measures 3.5 - 5.5 cm in length. Vulva opens at the ____________, the fleshy portion of the body. Has a single ____________________. Bluntly rounded at the posterior end.

1. 2. 3. 4.

Pathology: mild ulceration Abdominal pain Diarrhea “_____________ prolapse”

Diagnosis: 1. ________________________________ 2. Kato-Katz Technique 3. ___________________ Technique (Recovery of eggs in the stool specimen) 5

Prevention and Control: 1. Proper disposal of feces. 2. Hand ____________________. 3. AVOID using human fecal matter as fertilizer. 4. Community education.

Eggs: similar to that of the whipworm but are smaller about ____________________ micra usually in the single or 2-segmented stage of development more oval in shape _________________ plugs that are not protruberant shell is thick and pitted which appear as _______________ hence peanut-shaped

Treatment: 1. Piperazine citrate 2. ______________________ 3. Pyrantel Pamoate

Capillaria philippinensis Disease: - Intestinal Capillariasis - ______________________ History: - was 1st recognized in the Philippines in 1963 at PGH - ____________________, Ilocos Norte - 1967, epidemic in Capillariasis in Pudoc, West Tagudin, Ilocos Sur (approximately 1,300 persons became ill and 90 persons died of the infection)

Life Cycle: Infective Stage _______________________ Intermediate host _______________________ Definitive host - humans Diagnostic Stage _______________________

Morphology: Male Worm: Small, measuring ____________mm in length. Characterized by caudal alae and long, nonspiny sheaths 2 Types of Female Worm: Atypical Female – ___________________ (responsible for population build-up) Typical Female- _____________________ NB: Both has an esophagus with secretory cells called _____________________ and the esophageal structure is called _______________________________ Female Worm: Measures _______________ mm in length. Body is divided into 2 almost equal parts, the anterior containing esophagus and esophageal glands and the posterior containing intestine and reproductive system with slightly prominent vulva.

6

1. 2. 3. 4.

Pathology: Abdominal pain Gurgling of the stomach (________________) Loss of ________________ Vomiting and edema

Diagnosis: 1. Demonstration of characteristic ______________ in the feces. 2. Larva and adult stages may also be seen. Prevention and Control: 1. Proper disposal of feces. 2. Proper cooking of fishes. 3. Freezing of ____________________.

Egg (3 layers) 1. Albuminous covering - outer ______________ covering - serves as an auxiliary barrier to __________________________

Ascaris lumbricoides Common Name: - __________Worm - _______________ Intestinal Roundworm Diseases: - Ascariasis - Ascaris infection - ____________________ Infection

2. Hyaline Shell - ____________________ structure

Male Worm Measures ____________ cm with smooth striated cuticles. They have a terminal mouth with ____________ with a sensory papillae. They have a ventrally curved posterior end with two ______________________.

3. Vitelline Lipoidal Layer - highly impermeable Egg (3 Types) 1. Fertilized Egg measures ____________ micra by ____________ micra, shorter than the infertile eggs there is an outer coarsely mammilated albuminous covering _____________ yolk granules

Female Worm Measures ____________ cm with smooth striated cuticles. They have a terminal mouth with ______________ with a _____________ papillae. They have paired _____________ organs in the posterior 2/3. Posterior end is blunt. Productive capacity of 26 million eggs or 200, 000 eggs per day.

7

2. Unfertilized Egg measures ________ micra by 39 to 44 micra, longer and narrower than fertilized eggs it is _____________ with an irregular mammilated coating filled refractile granules they are difficult to identify and are found only in the ____________________.

3. Decorticated Egg ___________ of albuminous coating

Clinical Disease:

Life Cycle: Infective Stage - _____________ egg - embryonation in soil (_______ weeks)

1. Worm Ball – __________________ in the intestine 2. Ascaris pneumonitis- due _____________ __________________ in the lungs

Definitive Host - _______________________

Diagnosis: 1. Demonstration of characteristic ___________ in feces. 2. Recovery of adult worms from _________, nasal passage, or even _____________.

Diagnostic Stage - fertilized or unfertilized eggs in the feces

Prevention and Control: 1. Proper ______________ of feces. 2. Cooking well of vegetables. 3. Avoid using human feces ____________. 4. Proper _______________. Treatment: 1. Pipperazine citrate. 2. Mebendazole or pyrantel pamoate.

8

as

Infective Stage - Filariform Larva Definitive Host - Humans, Monkeys Diagnostic Stage - Rhabditiform Larva in

Strongyloides stercoralis Common Name: Threadworm Disease: Strongyloidiasis Conchin-China Diarrhea Morphology: Parasitic or Filariform Female: smallest nematodes measuring 2.2 x 0.04 mm it has a slender tapering anterior end and a short conical pointed tail the short buccal cavity has 4 indistinct lips the vulva is located 1/3 the length of the body from the posterior end the uteri contain a single file of eight to twelve thin-shelled, transparent, segmented ova Parthenogenetic/ parthenogenic

stool sample NB: Eggs hatch in mucosa of intestines and are rarely seen in feces. It has both a free-living and parasitic cycle.

Free-Living Female: measures 1 mm by 0.06 mm and is smaller than the parasitic female it has a muscular double-bulbed esophagus and the intestine is a straight cylindrical tube Free-Living Male: measures 0.7 mm by 0.04 mm and is smaller than the female it has a ventrally curved tail, two copulatory spicules, a gubernaculum but no caudal alae

Clinical Disease: A) Three stages based on Life Cycle 1. Cutaneous - initial skin penetration 2. Pulmonary - larval migration in the lungs 3. Intestinal - symptoms depend on worm load, immunocompromised patients may exhibit leukocytosis and eosinophilia

Rhabditiform Larva: measures 225 micra by 16 micra it has an elongated esophagus with a pyriform posterior bulb differs from hookworm in being slightly smaller and less attenuated posteriorly it also has a shorter buccal capsule and a larger genital primordium Filariform Larva: is the non-feeding stage slender measuring about 550 micra it is similar to the hookworm filariform larva but usually is smaller, with a distinct cleft (notched) at the tip of the tail

B) Hyperinfection Syndrome - may lead to death due to tissue damage - occurs in immunosuppressed patients (AIDS, drugs) - can be transferred through organ transplantation - transmammary

Egg: rarely seen in the stool specimen it has a clear, thin shell and are similar to those of hookworms except that they measure about 50-58 micra by 30 to 34 micra

C) Autoinfection - some of the rhabditiform larva develop into filariform larva in the bowel and reinfect the host

Life Cycle: 9

Diagnosis: Demonstration of _______________ and/or filarform larvae in the feces using: a) DFS b) concentration technique c) Baermann technique

Straight espohagus (1/4 of the length of the body) Pointed tail Life Cycle: Infective Stage - _______________ Definitive Host - humans Diagnostic Stage ____________________

Prevention and Control: 1. Proper sewage disposal. 2. Avoid walking barefooted. Treatment 1. ___________________ 2. Thiabendazole

Hookworms Necator americanus ________________________ Ancylostoma duodenale ________________________ Ancylostoma braziliense Ancylostoma caninum Ancylostoma ceylanicum Disease: - Ancylostomiasis - _______________ - Necatoriasis - _____________________

Clinical Disease: 1. Pneumonitis 2. Allergic Reactions 3. Anemia (each adult worm consumes ________ of blood/day) 4. Cutaneous Larva Migrans (due to migration of dog hookworms) * A. braziliense & A. caninum through the subcutaneous tissue causing itching and he formation of _____________________

Morphology: Male Worm: 8-11 mm long Posses a bursa (____________) which aids in the speciation of hookworms Exhibits dental pattern Female Worm: 10-13 mm long _____________ tail Adults may live 2-14 years Rarely seen in the stool since firmly attached to the mucosa

Diagnosis: 1. Demonstration of characteristic egg in the feces (________________ cell stages) Larva is not seen in feces (unless the specimen is left for 24 hours)

Rhabditiform Larva: _____________, feeding stage Bulbuous esophagus Long buccal cavity (approximately as long as the width of the body) _____________ genital primordium

R-E-M-E-M-B-E-R If a stool specimen is left at room temperature, the larva may continue to develop and must be differentiated with _____________________.. Diagnosis: Should you recover the adult Hookworm, easier differentiation is done by observing the buccal capsule.

Filariform Larva: ______________, non-feeding stage 700 um long

10

• • • • •

N. americanus – ____________ cutting plates A. duodenale – ______ pairs of ventral teeth A. caninum – ______ pairs of ventral teeth A. ceylanicum – ______pairs of ventral teeth with outer bigger than the inner pair A. braziliense – _______ of big teeth

the translucent shell consists of an outer, triple albuminous covering for mechanical protection and an inner lipoidal membrane for ____________ outside the host , eggs become infective in ________________________ Life Cycle: Infective Stage - ___________________ Definitive Host - Humans No IH needed Autoinfection is very possible

Prevention and Control: 1. Proper disposal of feces. 2. Avoid walking barefooted. 3. Health education on personal, family, and community hygiene. 4. Treatment of infected individuals. 5. Mass chemotherapy when prevalence is greater than ___________ 6. Protection of susceptible individuals. Treatment: 1. Albendazole 2. Mebandazole 3. _____________

Enterobius vermicularis Common Name: 1. ________________ 2. Sitworm 3. ________________ • Disease: 1. Enterobiasis 2. __________________

Pathology: 1. Perianal itching or _______________ 2. Autoinfection 3. Familial disease

Male Worm: Measures 2 to 5 mm by 0.1 to 0.2 mm. It has a characteristic curved tail with a single spicule. Relatively smaller that the female worm. They are rarely seen because they die after copulation.

Diagnosis: 1. Scotch tape technique (cellulose tape) - ____________ stick to the tape - since migration of female occurs at ___________, the method is performed before the patient’s bowel movement or before the patient has taken a bath - adults may become stuck to the outside of the stool as it passes the perianal folds where the female migrates to lay eggs

Female Worm: Measures 8 to 13 mm by 0.4 mm. It has a long ____________ hence the common name pinworm. The uteri of the gravid female are distended with eggs. They are capable of laying as much as 4, 672 to 16, 888 eggs/day.

Prevention and Control: 1. Proper hygiene. 2. Public Education. 3. Familial treatment.

Ova: are assymetrical, with one side flattened and the other side _____________ measures 50 to 60 micra by 20 to 30 micra averaging 55 by 36 micra 11

Blood and Tissue Nematodes

1. 2. 3. 4.

- allergic reaction due to worm migration in tissue and death in capillaries

The “microfilariae group” Wuchereria bancrofti Brugia malayi Loa loa Onchocerca volvulus

Diagnosis: - demonstrate in blood smears (thick and thin) sheathed microfilariae with continuous nuclei to the tip of the tail - found in Africa

Wuchereria bancrofti Onchocerca volvulus Also known as the “Blinding Worm” Disease: - Onchocerciasis - Onchocercosis - _____________________ Microfilariae - only pathogenic tissue nematode which is not sheathed - ____________ at the tip of the tail - found in nodules under skin, not in peripheral blood

Diseases: - Bancroftian filariasis - Wucheriasis - _________________ Microfilaria: - sheathed - no nuclei at the tip of the tail - norturnal periodicity (9pm-2am is its greatest concentration in the tblood) Elephantiasis: - permanent blockage of lymphatic system can occur in _________________ Diagnosis: - demonstrate in blood smears (thick and thin) sheathed microfilariae with ________________ at the tip of the tail

Clinical Significance/Disease: - sever dermatitis - microfilaria in ocular structures may result in blindness - leading cause of blindness in Africa Diagnosis: - demonstrate from skin snips/tissue scrapings unsheathed microfilariae with no nuclei in tail

Brugia malayi Disease: - Malayan filariasis Microfilariae: - sheathed - nuclei stops then there is a clear space with __________________ at the tip of the tail - exhibits ____________ periodicity Elephantiasis: - restricted to the ____________ extremities Diagnosis: - demonstrate in blood smears (thick and thin) sheathed microfilariae with __________ terminal nuclei in tail Generally found in the Far East

NB: _______________________ eosinophilia is associated with the microfilariae of these nematodes

Loa loa Also known as the _________________ Microfilariae - sheathed - nuclei _________________ of the tail - exhibits _________l periodicity (microfilaria is shed in peripheral blood constantly day or night) Causes ________________ swellings 12

Microfilariae

Disease

Arthropod Vector

W. bancrofti

Elephantiasis

Mosquito (Culex/ Anopheles)

Blood

B. Malayi

Elephantiasis

Mosquito (Mansonia)

Blood

L. Loa

Calabar swelling Blindness

Fly (Chrysops)

Blood

O. volvulus

River blindness

Fly (Simulian)

Tissue from nodule

LIFE CYCLE

Diagnostic stage found in

4. The development of the larva after entry to the bite wound into a mature worm at its selective site. Treatment/Prevention/Control 1. Control on mosquitoes and human sources of infection. 2. Spraying of houses with residual insecticides. 3. Diethylcarbamazime (DEC) 4. Ivermectin

1. Ingestion of the microfilariae from the blood or tissues by a blood-sucking insect. 2. The metamorphosis of the microfilaria in the arthropod vector 1st into rhabditiform larva and then into an infectious filariform larva. 3. The transfer of the infective larva to the skin of a new host by the proboscis of the biting insect. 13

Dracunculus medinensis

Males are small (1.2-2.9 cm long) Females measures 60cm in length The larvae, which measure between 500 and 700 micrometers, can live for 6 days in clean water and 2 to 3 weeks in muddy water.

Common Name: • ____________________ • ____________________ • Medina Worm Disease: • Dracunculiasis

Life Cycle Infective Stage – ______________ Definitive host – humans, dogs, horses Intermediate host - ________________

parasite is frequently found in the subcutaneous tissues and mucscles of humans, dogs and sometimes cattles and horses The disease causes cutaneous nodules and subsequent ulcers.

Treatment: • Removal of Worm • Filtering water sources • Avoid contact with contaminated water

Morphology

Angiostrongylus cantonensis

- 16 to 19 mm x 0.26 mm in diameter - they have a well-developed caudal bursa (kidney-shaped and single-lobed)

Common Name: • ____________________ • Was described by Chen in 1935 from domestic rats in Canton, China • The worm normally lives in the lungs of rats but can cause eosinophilic meningoencephalitis in man

Female: - pale and filiform - 21 to 25 mm x 0.30-0.36 mm in diameter - has uterine tubules which are round spirally around the intestine (__________________) - lays 15,000 eggs/day

Disease: • Angiostrongyliasis • Eosinophilic meningoencephalitis

Eggs • • •

Morphology • Male: - pale and filifprm 14

Have delicate hyaline shells Measure 46-48 micra x 68 micra Unembryonated when oviposited

Life Cycle • Infective stage – 3rd stage larva • Definitive host – rats, humans • Intermediate host – snails (Achantina fulica)

Treatment • No antihelminthic treatment is recommended • Thiabendazole, Medendazole, Albendazole, Ivermectin (effective in experimental animals) Prevention/Control • ______________________ • Safe food preparation • Elimination of IH • Washing of leafy vegetables • Eating sufficiently cooked prawns and crabs

Diagnosis • Relatively difficult • Presumptive diagnosis is made by travel history and exposure • CSF (10% eosinophilia in proportion to the WBC) • CT Scan • ELISA

15