Phylum Sarcomastigophora Subphylum Mastigophora

Family Trypanosomatidae

Blood and Tissue Flagellates

Have not been diagnosed in the Philippines

Because of fast and easy travel as well as an increase in human migration imported cases may become the future source of infection

Vectors: Triatoma and Rhodnius, Phlebotomus spp. bugs are found in the country

Characteristics of Trypanosomatidae

All have single nucleusAll have single epitheliumDuring one stage of their lives they live in the blood or

tissue of all classes of vertebratesAnd one stages they live in the intestine of blood

sucking invertebrates

Trypanosome cellular architecture

Nucleoulus

Nucleus

Kinetoplast

Flagellum

Kinetosome

Kinetoplast

Nucleus

Undulating membrane

Four Morphological

Forms

Morphological forms

Leishmania spp. – amastigote and promastigote forms only

Trypanosoma brucei – epimastigote and trypomastigote forms only

Trypanosoma cruzi – contains all 4 morphological forms

Trypanosoma brucei

Trypanosoma brucei gambienseTrypanosoma brucei rhodesiense

There are two groups of trypanosomes

Develop in the posterior digestive tract of the insect (Salivaria)

Develop in the posterior digestive tract (Stercoraria)

T. brucei group - African sleeping sickness

Gambian or West African sleeping sickness

West and Central Africa

Rhodesian or East African sleeping sickness

East and South Africa

Morphology

T. brucei group exhibits only the epimastigote and trypomastigote forms

Typical trypomastigote stages with a posterior kinetoplast, a centrally located nucleus, an undulating membrane, and an anterior flagellum

polymorphic (slender, short, stumpy forms

Tsetse flyThe tsetse fly feeds on the blood of animals and

humans. Once inoculated by an infected fly, the

trypanosomes proliferate and gradually invade all the organs of the host.

Most of the parasites are effectively destroyed by the host's natural defenses,

but some trypanosomes manage to evade the immune system by modifying their surface membrane, a process known as antigenic variation.

The trypanosome can express thousands of variants, multiplying with each new surface change.

Well fed tsetse

T. brucei in blood smear

tsetse fly feeding

Pathogenesis

Stage 1 (early, or hemolymphatic, stage)

Painless skin chancre that appears about 5-15 days after the bite

Intermittent fever (refractory to antimalarials), general malaise, myalgia, and headache usually 3 weeks after bite

Generalized lymphadenopathy

Pruritus, urticaria, and facial edema (minority of patients)

Stage 2 (late, or CNS, stage)

Persistent headaches (refractory to analgesics)

Daytime somnolence followed by nighttime insomnia

Behavioral changes, mood swings, and, in some patients, depression

Loss of appetite, wasting syndrome, and weight loss

Seizures in children (rarely in adults)

African Trypanosomiasis

Characterized by irregular episodic fever

Lymphadenopathy

Progressive central nervous system

Coma

death

DIAGNOSISLymph node and chancre aspirate

Lymph node is commonly used as a rapid test for trypanosomes at a high dry magnification (X 400). It requires immediate search for parasites because they are mobile for only 15-20 minutes.

Chancre aspirate can be used as a wet preparation, especially in the East African form of the disease, but a blood smear is more sensitive.

Blood smear

A wet smear of unstained blood or Giemsa-stained thick smear (more sensitive) is used to observe the mobile trypanosomes, for 15-20 minutes. Wright and Leishman stains are inadequate

hematocrit centrifugation technique for buffy coat examination

miniature anion-exchange centrifugation technique, which filters out the red cells but not the trypanosomes.

Serology

The standard assay is the card agglutination test for trypanosomiasis (CATT) to diagnose West African trypanosomiasis.

The CATT can be conducted in the field without electricity-results are available in 10 minutes.

highly sensitive (96%) but less specific because of cross-reactivity with animal trypanosomes.

TREATMENTTripanosomias Medications

Stage 1 (Hemolymphatic

Stage)MedicationsStage 2 (Neurologic [CNS] Stage)

East African TrypanosomiasisTrypanosoma brucei rhodesiense

Suramin 100-200 mg IV test dose,

Eflornithine 400 mg/kg/d

Melarsoprol 2-3.6 mg/kg/d IV for 3 d;

Eflornithine 400 mg/kg/dWest African TrypanosomiasisTrypanosoma brucei gambiense

Pentamidine isethionate 4 mg/kg/d IM for 10 dSuramin 100-200 mg IV test dose, orEflornithine 400 mg/kg/d IV

Melarsoprol 2-3.6 mg/kg/d IV for 3 d; after 1 wk, 3.6 mg/kg/d for 3 days; Eflornithine 400 mg/kg/d IV in 4 divided doses for 14 d

Prevention and ControlA vaccine is not available.Effective prophylaxis in not available. Tsetse fly trapping is possible but costly. Treatment of asymptomatic carriers is possible, and infection can be

detected by CATT or node aspirate and confirmed with smears.Wear protective clothing with dull colors and use bed nets in areas

with tsetse flies. Insect repellant is not as effective in preventing illness transmitted by

tsetse flies compared to other insect-borne diseases.Avoid areas where African trypanosomiasis (sleeping sickness) is

endemic.

Trypanosoma cruzi

Trypanosoma cruzi

The parasite is found throughout much of central and northern South America, Central America, and Mexico

In humans, T. cruzi is found as both an intracellular form, the amastigote, and as a trypomastigote form in the blood.

The vector for Chagas' disease, a "true bug" (Hemiptera) such a Triatoma or Rhodnius

Morphology

Exhibits all four stages

Trypomastigotes found in the bloodstream in man

Amastigotes in tissue cells

T. cruzi trypomastigote is similar in form to T. brucei

VECTOR - genera

Triatoma, Panstrongylus, and Rhodnius

- common names: cone-nosed bug, assassin bug, kissing bug, vinchuca

 

.

Triatoma and Rhodnius bugs-vector

Chagas’ disease/American trypanosomiasis

Intracellular parasite

Humans:trypomastigotes-bloodstream

Amastigotes-tissue cells

Bugs:amastigote, epimastigote and promastigote-midgut

Pathogenesis

American trypanosomiasis

At the site of inoculation – inflammation known as “chagoma” – reddish nodule from acute to chronic cases

Fever and lymphadenopathy – acute disease

May enter through the conjunctiva of the eye – causing edema of the eyelid “romana sign”

Pathogenesis

In the human host, Chagas' disease affects primarily nervous system and heart. 

Chronic infections result in various neurological disorders, including dementia, megacolon, and

megaesophagus, and damage to the heart muscle.  Left untreated, Chagas' disease is often fatal.

Diagnosisobservation of the parasite in a blood smear (acute

phase)demonstration of trypanosomes in blood, CSF, fixed

tissue or lymphBlood culture and xenodiagnosisSerological

IFAT, Compliment fixation test, IHAT, PCR

Dot-immunobinding assay – using antigen bound to nitrocellulose paper

PCR

Prevention and Control

Vector control

Screening and sterilization of transfusion blood

Health education

Insecticide spraying and housing improvement to reduce breeding sites of triatome bugs.

Leishmanias

Leishmania tropicaLeishmania braziliensisLeishmania donovani

Leishmanias

Occur in the southern region of North AmericaMediterranean basinEast and North AfricaArabian PeninsulaPersian Gulf regionChina, and Southern Soviet UnionMost severe forms are found in Africa, Latin America

and India

Parasite biologyLeishmanias

produce amastigotes intracellularly in the mammalian host

Promastigote in the midgut and proboscis of the insect vector

LeishmaniasisAmastigote

Ovoid or rounded

Live intracellularly in monocytes, polymorphonuclear leukocytes, endothelial cells

Nucleus is large

Promastigote

Have single free flagellum arising from the kinetoplast at the anterior end

Leishmania spp.

Leishmania tropica – seen around the Mediterranean Sea, Middle East to Central Asia, China and India

Leishmania donovani – Mediterranean Sea, in Africa, India, China, and also in South AmericaTransmitted by sand flies of the genus Phlebotomus

Leishmania braziliensis – Mexico through Central America to South AmericaTransmitted by sand fly genus Lutzomyia

Cutaneous leishmaniasisLeishmania tropica minor – usually features single

solitary ulcerating lesions on the exposed parts of the skin

Leishmania tropica major – is the common important species responsible for zoonotic leishmaniasis and features multiple cutaneous lesions

Leishmania aethiopica – causes a range of lesions from solitary lesions to diffuse cutaneous involvement and to mucocutaneous leishmaniasis

Clinical feature

Incubation period varies between 2-8 moLesion starts at the site of infection → nodule →

ulceratesThis heals in about 6 moThere is an assoc. life long immunity from disease

Cutaneous leishmaniasis is marked by sores that often look like

volcanoes: they have a central pit and a raised

rim. They can be painful or painless and

may be covered by scabs. The sores tend to appear on the face,

arms, and legs, and some people have as many as 200 of them.

Patients with cutaneous leishmaniasis also may have swollen lymph nodes* near the sores

Mucocutaneous leishmaniasis

Caused by Leishmania brazillensis

Vector is Lutzomyia sand fly

Disease starts as cutaneous leishmaniasis

During the course of primary infection or several yrs after healed there is metastatic spread to involve the oronasal or the pharyngeal mucous membrane

Disease is called espundia

Mucocutaneous…

Mucosal involvement takes the form of an ulceration and erosion of soft tissues and cartilage with serious deformities

It may be painful or painlessDisease does not heal spontaneously and death is

due to malnutrition or secondary bronchopneumoniaIndividual w/ mucocutaneous leishmaniasis show both

a strong cell mediated immune rxn and presence of circulating ab.

Mucocutaneous Leishmaniasis

Ulcers on the oral or nasal mucosa. If untreated, all of the nasal mucosa will be infected and the septum will be destroyed.

This form of the disease usually spreads more widely than the cutaneous form.

Leishmania braziliensis pathology1. Promastigotes inoculated into skin transform into amastigotes

and enter skin macrophages

2. Amastigotes metastasize and spread to the mucocutaneous zones

• secondary lesion:nasal system and buccal mucosa causing degeneration of cartilage and soft tissues.

• ulceration may involve mucous membranes and cartilaginous tissues of the lips, nose, palate, and pharynx are destroyed; larynx may also be involved, destroying voice

Leishmania donovani

Causative agent of visceral leishmaniasis

Identified by William Leishman in 1900 from a soldier who died of fever in Dum-Dum, India. Charles Donovan identified the parasites in the spleen of an infected person in 1903. Parasite is named in honor of these two men.

Vector – Phlebotomus spp.

Leishmania donovani

• Amastigotes multiply in macrophage, eventually rupturing the cell

• Free amastigotes then invade the circulatory system.

Pathogenesis

May range from asymptomatic to fully develop kala-azar

Fever, malaise

Wasting and anemia

Protrusion of abdomen from enlarged liver and spleen leading to death

Pathogenesis

Visceral leishmaniasis may be viewed as disease of RES, the phagocytic cells:habitat of parasiteBlood forming organ:bone marrow and spleen

undergo production of macrophages and other phagocytes to the detriment of red cells production.

The spleen and liver become greatly enlarge “hepatospleenomegaly”

Visceral LeishmaniasisAbdominal swelling without

definite illness, anemia, dermal nodules or lesions resembling leprosy. Diagnosis is made by visualizing the parasite. Samples taken from a sternal marrow aspiration

Leishmania donovani

DIAGNOSISDIAGNOSIS

visceral leishmaniasis-blood sample and/or taking a biopsy from the bone marrow to show the parasite.

cutaneous leishmaniasis will require a small biopsy or scraping of the ulcer.

mucocutaneous leishmaniasis requires a biopsy of the affected tissues.  

Biopsy samples are examined by microscopy, culture and other methods to look for the parasite and identify the specific kind of Leishmania causing the ulcer. Some of these methods will give results within a few days, but culture may take 2-4 weeks to demonstrate the parasite.

Prevention

Control of sand flies

Protect wound from insect bite

Health Education in endemic areas

End of Blood and Tissue Flagellates….

Thank you!By: Hazel Carbon-Granil, RMT, MiB, MSMT