Balantidium coli

 

·       The only pathogenic ciliate protozoan of humans. It is the largest protozoan parasite of humans. It is present worldwide, but the prevalence of the infection is very low.

·        More common where pigs reared and pigs faeces used as fertilizer in warmer climates.

·        Habitat – trophozoite & cyst in large intestine of pig and rarely man.

·       B. coli occur in two stages - the trophozoite and cyst.

1. Trophozoite

• Oval, with one pole more rounded than the other.

·        Rapid motility using the cilia, crossing the field in a definite direction and sometimes turning in circle.

o   Cover the whole body and longer around the cytostome called adoral cilia.

·        One large kidney-shaped macronucleus and one small micronucleus.

·        Cytostome: a sort of mouth that contracts and expands to draw in debris. The anterior end is narrow and the posterior broad. The anterior end is pointed and has a groove (peristome) leading to the mouth (cytostome) terminating in a short funnel-shaped gullet (cytopharynx).

·        The posterior end is broadly rounded and has a small an excretory pore (cytopyge).

§  Cyst

• It is the infective stage. Shape:  round or spherical. Shell:  thick double-layered wall
• Nucleus:  similar to the trophozoite. Cilia: inside wall, sometimes can be seen in younger or newly formed cysts. The contractile vacuoles are present in the cysts also.

v Transmission

§  Through ingestion of contaminated food or water as well as hands contaminated with pig faeces containing cyst.-Faecal-oral-route transmission.

v Life cycle

·        Man most often acquires the cysts through ingestion of contaminated food or water.

·        Excystation occurs in the small intestine. From each cyst, a single trohpozoite is formed and the liberated trophozoites colonize the large intestine.

·        The trophozoites reside in the lumen of the large intestine of humans and multiply by binary fission, or conjugation may occur.Conjugation occurs infrequently, during which reciprocal exchange of nuclear material takes place between two trophozoites. Conjugation is sexual fusion of two cells which is an important aspect of this parasite in its life cycle.

·        Encystation occurs as the trophozoites passes down the colon to produce infective cysts.

·        Mature cysts are passed with faeces.

 

v Clinical features

·       Clinical manifestations, when present, include persistent diarrhea, constipation, occasionally dysentery with blood & mucus, abdominal pain, nausea, vomiting, intestinal colic, and weight loss.

v Diagnosis

·        Diagnosis is based on detection of the parasite in stool specimens.

·        Generally, B. coli  is easy to recognize in stool specimens during microscopic examination due to: Its large kidney-shaped macronucleus.; Its large size. And Its cilia which covered the outer membrane.

v Prevention and control

·       Avoidance of contamination of food and water with human or animal faeces containing cysts.

·       Keep personal hygiene especially those who keep pigs. And Treatment & health education.

Wuchereria bancrofti ·

Has a spotty world-wide distribution throughout the tropics and subtropics, Africa, Asia, and S. America.

·      Microfilaria prefers climate with humidity and heat.

·      More than 400million people are at risk

o   8  million are infected

v Habitat

o   Adults: - coiled in lymphatic glands,lying in lymphatic vessels,

o   Microfilariae-

§   in lymphatic vessels,in the peripheral blood (at night),in the lung and other internal organs (at day)

§  Infective larvae; - In the gut and muscles & mouth parts of certain species of mosquitoes of the genus (Culex, Aedes, Anopheles).      

v Morphology

o   Male- Tapered and round swollen head and Sharply curved tail with two unequal spicules

                                                                                                                                                                          

o   Female- longer than male

                          - Curved tail tapered front end and vulva at a cervical area.

¨    Microfilariae (275-300µm)

·        Has a sheath which stain –pink with Giemsa and Pale with heamatoxylin stain

·        Body nuclei- are fewer and more distinct than other species and with no nuclei at the end of the pointed tail.

·        Body curves are smooth and few with smooth cuticle and bluntly rounded anteriorly and pointed caudally                                 

v Pathology & clinical features

·        Causes lymphatic(bancroftian ) filariasis  or elephantiasis

·        Affected organs – limbs, genital organs, and breasts

·        Pathology of the parasite is due to adult worms due to immunopathogensis

Ø  As the worms dies host immune reactions continues - a fibro-proliferative granuloma obstructs the lymphatic vessels -swelling & fibrosis - lymphedema  -  bacterial infection          =Elephantiasis.

v Major symptoms:

·        Recurrent attacks of fever, and Painful inflamed lymphatics,

·        Enlarged lymph nodes = swollen lower extremities,  rarely genital organs, and breasts

·        Stretched skin is susceptible to traumatic injury and bacterial infections.

                           = Elephantiasis, enlargement of the lower limb

v Laboratory diagnosis

Ø  Specimens- blood, urine, aspirates and Sample collection depends on the periodicity of species

v Method: Microscopy

·        Wet or stained blood films

·        Immunological (antigen) detection.

v Prevention & control

·        Controlling mosquitoes vector,

·        Avoid mosquitoes bite,

·        Treatment & health education

 

 

 

Burgi malayi -Malaysian filarisis / lymphatic filariasis/

   

v Habitat:

Ø  Same with W.bancrofti

v Life cycle & transmission

·        Similar to the life cycle of W. bancrofti,

·        Man is definitive host,

·        Female Anopheles and Mansoni mosquitoes are the intermediate hosts.

v Pathology

·        Causes Malayan filariasis / elephantiasis of the lower limbs

·        Symptoms develop rapidly and children are more affected.

v Prevention & control,Lab. Diagnosis-= similar to W. bancrofti

 

Loa loa –Eye worm

 v Habitat

·      Adults- In connective tissues under skin and in the subconjuctival tissues of the eye, or in thin skinned areas.

·      Mf -In peripheral blood of man during day time.

·      Infective larvae- In the gut, mouth parts, and muscles of Tabanide fly of the genu-Chrysops (Horse flies).

v Morphology: 

·      Adults -cylindrical & transparent

·      Mf - has several kinks and curves

Ø  A sheath which stains best with heamatoxylin.

Ø  Body nuclei – are not distinct and appear denser than W. Bancrofti

Ø  Nuclei extend to the end of the tail which is rounded.

v Life cycle and transmission

·        Horse flies (Tabanidea) in the genus Chrysops is the vector

·        Day feeding and forest –dwelling

·        Also called the “dear fly” or mango fly

·        Adult worms continuously migrate through tissues at a rate of about 1 cm per minutes

·        Found in back, chest, axilla, groin, penis, scalp and eyes

v Pathology and clinical features

·        Swelling known as calabar swelling in the arm.

·        Adult also migrate to sub – conjunctiva tissues-----Cause inflammation & irritation but not

v Lab. Diagnosis AND Prevention & contro l=== similar to other filarial worms.

·         

Onchocerca volvulus – “River blindness” – Onchocercasis

o   Geog. Distribution -Endemic in tropical rainforest of Africa, south & Central America

o   Affecting

·        40 million people d world-wide

·        2 million people are blind due to the disease

o   Infection is commonly found near rivers and streams where the black flies (the vector for the disease) prefer fast running streams for breading.

Ø  Because of its association with river and because of the blindness it causes it’s known       as “River blindness”

v Habitat

·        Adults- Subcutaneous nodules and in skin

·        Mf- skin, eye, and other organs of the body.

·        Infective larval – in the gut, mouth parts and muscles of the genus Simulium (black fly)

v Morphology

·        Adults – curved and bulbous tail

·        Mf – has – no sheath and head end is slightly enlarged.

·        Anterior Nuclei – are positioned side by side.

·        No nuclei at the end of tail which is long and pointed.

v Pathology and clinical features

·        The Pathologic changes are due to microfilaria.

·        The subcutaneous nodules containing the adult worm cause little pathology.

o   Two forms of disease.

    1.     Ocular lesion

·        Nodular and erythematosus lesions in the skin, subcutaneous tissue, and eye

·        Ocular involvement consists of trapped microfilaria in;

·        The cornea, choroids, iris, and

·        Anterior chambers of eye – photophobia- lacrimation and blindness.  

     2. Dermatitis /skin disease

Ø  Elephant skin

Ø  Hanging groin- When the skin around groin become affected

v Laboratory diagnosis

·        Microscopy - Skin examination (‘Onchocerca nodule’)  wet smear with normal saline,Skin biopsy

·        Eye examination

·        Immunodiagnostic

v  Prevention and control

·        Destruction of Simulium – insecticide,

·        Avoid Simulium bite

Treatment of community