MEDICAL PARASITOLOGY & ENTOMOLOGY LECTURER: SR. NORAZSIDA RAMLI

BLOOD & TISSUE FLAGELLATES/ HAEMOFLAGELLATES

Morphologic forms There are 4 morphologic forms seen in hemoflagellates: 1) Amastigote 2) Promastigote 3) Epimastigote 4) Trypomastigote -they can exist in two or more of the 4 morphologic forms  depending on the species.

Kingdom: Protisata Phylum: Sarcomastigophora Class: Zoomastrgophora Order: Kimetplastida Family: Trypanosomatidae Genus: Trypanosoma Species: brucei, cruzi, rangeli

Trypanosoma sp. T. brucei gambiense - cause: West African sleeping sickness T. brucei rhodesiense - cause: East African sleeping sickness T. cruzi - cause: American trypanosomiasis or ‘Chagas’ disease. T. rangeli - Cause: T. rangeli infection.

T. b. gambiense Cause West African sleeping sickness. “tsetse fly belt” is a large area of Africa that has reported cases of African sleeping sickness. Vector/ intermediate host: Glossina (tsetse) fly.

T. burgei gambiense

Tsetse fly

West African sleeping sickness Also known as Gambian trypanosomiasis. Can be found in the wet lowlands and rainforest of west and central Africa where the tsetse breed in the moist areas around riverbanks. Chronic course- ends with central nervous involvement and death after several years of durations.

Geographical distribution The savanna vectors G.morsitans and G. palidipes are responsible for the transmission of T. rhodesiense in East Africa, while the principal vectors of west African sleeping sickness are G. palpalis, G. fuscipes and G. tachinoides.

Life cycle of T.brucei

Transmission Occurs through: - the bite of an infected tsetse fly, - blood transfusion, - Organ transplant, and - congenital transmission (from pregnant mother to fetus).

Pathogenesis Infection is characterized by 3 progressive stages: 1) An asymtomatic incubation period -right after infection -a few days to several weeks. -non African shorter than African natives. -parasite multiply locally. -local inflammation leads to the development of a painful ulcerative lesion called: trypanosomal chancre at the bite site.

2) Hematogenous spread of the parasites and the involvement of the lymphatic system. - Trypomastigotes may be seen in the blood film examination. - Symptoms: febrile (fever) followed by afebrile periods, headache, malaise, weakness, anorexia, and night sweats. - Glandular enlargement and lymphadenopathy (enlargement of the lymph nodes). - Enlargement of the postcervical chain of lymph nodes, which is known as ‘Winterbottom’s sign’.

Symptoms of glandular stage: -erythematous (red) rash -pruritus (severe itching) -localized joint edema (swelling) -delayed sensation of pain (Kerandel’s sign).

3)Meningoencephalitic stage -CNS involvement -6 months to a year after the onset of 1 st symptoms. -the patient’s health deteriorates with increased fatigue -mental dullness -apathy -diminished motor control -somnolence (excessive sleepiness) -emaciation -trypomastigotes may be seen in the patient’s spinal fluid -sleepiness progresses to coma and eventual death

Diagnosis Microscopic examination Concentration technique – centrifugation Serologic technique – Card Agglutination Trypanosomiasis Test (CATT)

Treatment Pentamidine isothionate -used to cure Gambian trypanosomiasis in the hemolymphatic stage of infection. -administered by intramuscular injection. -effective only in the early stage of disease bcoz of its inability to cross the ‘blood- brain barrier’.

Suramin - Effective only in the early stage of disease b4 CNS involvement - Administered intravenously - Has more toxic side effects than pentamidine. - May be prescribed during pregnancy.

Melarsoprol - A triavalent arsenic compound. - Much more toxic than pentamidine or suramin. - Effective for later stages - Administered intravenously - Can effectively penetrate the blood brain barrier

Prevention Control, management & avoidance of the insect vector Clearing of vegetation where tsetse flies breed Wide use of insecticides Travelers to endemic areas encouraged to wear long sleeved protective clothing Wear thick Khaki or olive drab clothing coz tsetse flies are attracted to bright and dark colors. Use bed net Insect repellent

T. burgei rhodesiensi

T. brucei rhodesiense Course of East African sleeping sickness 1 st isolated from a patient in Rhodesia Clinical presentation- more fulminant course and severe symptoms The incidence is far less than Gambian disease but if left untreated – death will ensure within several weeks to months rather than years.

Life cycle Similar to T.b. gambiense

Transmission Transmitted by the bite of an infected tsetse fly: -G. pallidipes -G. morsitans -G. swynnertoni

Pathogenesis Produce a more acute form Stages of disease and symptomology similar with Gambian infection. Disease progress rapidly Much shorter clinical course Incubation period: shortened by the abrupt onset of febrile episodes

Laboratory diagnosis Similar to T.b.gambiense

Treatment No vaccine available

T. cruzi Cause of American trypanosomiasis/ chagas disease. Chagas disease: named for the Brazilian medical student, Carlos Chagas – who has discovered the parasite in Has an intracellular amastigote stage that develops in cardiac, brain and visceral tissues. Also has trypomastigotes in the peripheral circulation.

T. cruzi

Geographical distribution

Life cycle of T. cruzi

Trypanosoma cruzi vector Triatomine bug,, defecating on the wound after taking a blood meal

Reduviid bug - triatoma species

Ideal habitat for reduviid bugs

Transmission Transmitted by : reduviid bug -also known as kissing bug or triatomid bug. -vector: genus Panstrongylus or Triatoma Transmitted via: -the bite of infected vector -blood transfusion -transplacental route -accidental ingestion of an infected insect

Treatment NifurtimoxAllupurinolBenznidazole Diuretic treatment Surgical intervention