Negative Effects of African Trypanosomiasis

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Negative Effects of African Trypanosomiasis

• (3) Other
• Presence of tsetse flies have affected the
  environment.
• Pesticides!

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Negative Effects of African Trypanosomiasis

• (3) Other
• Presence of tsetse flies have affected the
  environment.
• Pesticides!
• Presence of tsetse flies have affected the
  climate.
• Cattle are underweight.
• Many regions have extensive over-grazing.

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Negative Effects of African Trypanosomiasis

• (3) Other
• Presence of tsetse flies have affected the
  environment.
• Pesticides!
• Presence of tsetse flies have affected the
  climate.
• Cattle are underweight.
• Many regions have extensive over-grazing.
• Aesthetics.
• How many wild animals can we live with?

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American Trypanosomiasis

• Trypanosoma cruzi Causative agent of Chagas
  Disease.
• Trypanosoma rangeli non-pathogenic species in
  humans.

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T. cruzi
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T. rangeli
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Transmission

• Transmitted by biting insects in the order
  Hemiptera.

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Transmission

• Transmitted by biting insects in the order
  Hemiptera.
• Family Reduvidae (Assassin bugs, Reduvids, or
  Kissing bugs).

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Transmission

• Transmitted by biting insects in the order
  Hemiptera.
• Family Reduvidae (Assassin bugs, Reduvids, or
  Kissing bugs).
• 28 species however most important are
• Triatoma infestans
• Triatoma sanguisaga
• Panstrongylus megistus
• Rhodnius prolixus

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• Large up to 34 mm.
• Some species found on the ground, some in trees
  and some in human dwellings.
• Eggs, are laid and have 5 nymphal instars.

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Kissing Bug Feeding on a Person
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How do People Get Infected?

• Epimastigotes are not found in the salivary
  glands, but instead gather in the rectum of the
  kissing bugs.

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How do People Get Infected?

• Epimastigotes are not found in the salivary
  glands, but instead gather in the rectum of the
  kissing bugs.
• In order to get infected epimastigotes must come
  in contact with mucous membranes or open wound!

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• Most of these bugs usually defecate at the same
  time as they are feeding!

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Main Difference From African Trypanosomiasis

• Trypomastigotes do not persist long in the
  circulatory system and they also do not reproduce
  there.

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Main Difference From African Trypanosomiasis

• Trypomastigotes do not persist long in the
  circulatory system and they also do not reproduce
  there.
• Instead they move into muscle cells where they
  become amastigotes and reproduce by binary
  fission.

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1. Epimastigotes transmitted through bug feces.
2. Trypomastigotes found in the peripheral blood.
3. Amastigotes reproduce in muscle cells.

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• In American trypanosomiasis transmission is
  Stercorarian or Posterior Station!

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Distribution
Primarily in costal areas of US and a few reports
in Texas and Arizona!
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Epidemiology
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Dogs and Cats can serve as hosts!
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Dogs and Cats can serve as hosts!
Chickens serve as good blood source for bugs!
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T. cruzi in North America
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• Sow Why dont people get infected?

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Vectors

• Triatoma gerstaeckeri
• Triatoma sanguisuga

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Vectors

• Feeding habits of T. sanguisuga and T.
  gerstaeckeri differ from their Latin American
  counterparts.

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Vectors

• Feeding habits of T. sanguisuga and T.
  gerstaeckeri differ from their Latin American
  counterparts.
• T. sanguisuga and T. gerstaeckeri are very
  cautious and neither will walk completely onto a
  host, reducing the chances of defecating on the
  host.

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Vectors

• Feeding habits of T. sanguisuga and T.
  gerstaeckeri differ from their Latin American
  counterparts.
• T. sanguisuga and T. gerstaeckeri are very
  cautious and neither will walk completely onto a
  host, reducing the chances of defecating on the
  host.
• Both T. gerstaeckeri and T. sanguisuga generally
  do not defecate while feeding, reducing fecal
  contact with the wound even further.

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• So how do the reservoir hosts become infected?

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American Trypanosomiasis Course of Infection

• There are three phases.

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American Trypanosomiasis Course of Infection

• Phase I. Trypomastigotes in peripheral
  circulation.
• Edema at site of bite (often eye and cheek) if
  on other area of the body than local inflammation
  produces a small red nodule (Chagoma) which is a
  swelling of the regional lymph node.
• Headache, fever, prostration.

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American Trypanosomiasis Course of Infection
Romañas Sign
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American Trypanosomiasis Course of Infection

• Phase II. Trypomastigotes enter cells.
• Symptoms of phase I subside or become absent.

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American Trypanosomiasis Course of Infection

• Phase III. Amastigotes within cells.
• Almost any cell can be invaded however they most
  commonly invade cells of the reticuloendothelial
  system in the spleen and liver, and cardiac,
  smooth and skeletal muscles, additionally the
  nervous system may be infected.

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American Trypanosomiasis Course of Infection

• Phase III. Amastigotes within cells.

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American Trypanosomiasis Course of Infection

• Phase III. Amastigotes within cells.
• Edema abnormal accumulation of fluid in the
  tissue spaces (cellular level)
• Inflamed lymph glands
• Enlarged spleen and liver (hyperplasia)

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Pathology of Trypanosoma cruzi

Chronic phase - occurs in adults. Apex of heart
usually becomes very thin. Impulses into
ventricles are affected. 
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American Trypanosomiasis Course of Infection

• Phase III. Amastigotes within cells.
• Heart muscles
• Fibers separated, inflamed
• Fibers weakened/ myocardial dysfunction ?
  (irregular heartbeat)
• Invasion of connective tissue which will cause an
  enlarged heart
• Nerve ganglia destroyed/ cardiac arrest

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Pathology of Trypanosoma cruzi

• Megaesophagus and Megacolon.

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Pathology of Trypanosoma cruzi

• Megaesophagus and Megacolon.
• Muscle tone and peristalsis is destroyed.

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Pathology of Trypanosoma cruzi

• Megaesophagus and Megacolon.
• Muscle tone and peristalsis is destroyed.
• Organs increase their diameters greatly.

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Pathology of Trypanosoma cruzi

• Megaesophagus and Megacolon.
• Muscle tone and peristalsis is destroyed.
• Organs increase their diameters greatly.
• Victim may not be able to swallow
  and dies from starvation.

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Pathology of Trypanosoma cruzi

• Megaesophagus and Megacolon.
• Muscle tone and peristalsis is destroyed.
• Organs increase their diameters greatly.
• Victim may not be able to swallow
  and dies from starvation.
• Feces not formed effectively.

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Pathology of Trypanosoma cruzi

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Diagnosis

• Demonstration of trypanosomes in blood, but this
  is very difficult.
• ELISA
• Xenodiagnosis

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Xenodiagnosis
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Prognosis and Epidemiology

• Not Good!! No effective treatment!
• 12-19 million people infected in the early 1990s
  in Central and South America!
• Currently about 25 of people are infected in
  Latin America!

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Prognosis

• Not all people die from it!
• Children have acute cases and within a month die.
• Adult infections are more chronic.
• Have shorter life span
• 30 die!