Chagas' disease

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Chagas' disease

• Causative agents
• Trypanosoma cruzi
• Other name American trypanosomiasis
• A systemic protozoal disease

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Chagas' disease

• History
• Carlos Chagas' - a Brazilian physician whose
  initial focus while in medical school was the
  control of malaria
• in 1909, discovered a Trypanosome organism in cat
  and an infected 2 year old girl
• named it in honor of his mentor, Oswaldo Cruz
• over the next few years, described the entire
  life cycle and natural history of the disease

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Chagas' disease

• Trypanosoma cruzi (blood smear)

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Chagas' disease

• Epidemiology
• Occurrence endemic in rural Mexico, Central and
  South America occurs in southern US, but also
  seen in Utah and California
• Frequency/distribution estimated 16-18 million
  people in endemic areas are infected (not
  including Mexico and Nicaragua)

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Chagas' disease
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Chagas' disease

• Epidemiology - vector distribution

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Chagas' disease

• Epidemiology
• Reservoir endemic in rural Mexico, Central and
  South America occurs in southern US, but also
  seen in Utah and California

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Chagas' disease

• Epidemiology - case distribution (humans)

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Chagas' disease

• Epidemiology
• Vector Reduviid bugs (cone-nosed or kissing
  bugs) - blood sucking reduviids
• Triatoma infestans, T. braziliensis, T.
  dimidiata, T. sordida, Panstrongylus megistus,
  Rhodnius prolixus) are primary vectors
• species that colonize poorer quality rural housing

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Chagas' disease

• Triatoma infestans

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Chagas' disease

• Vector triatome

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Chagas' disease

• Epidemiology
• Mode of transmission
• contamination of wound site, conjunctiva, or
  mucosa by infected feces of insect
• blood transfusion
• ingestion of infected triatomes in some animals
  (sylvatic cycle)

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Chagas' disease

• Epidemiology
• Life cycle
• typomastigotes - infective form, in blood stream
  of vertebrate host and in insect
• vector becomes infective from 10-30 days after
  biting host, infected for life (up to 2 years)
• epimastigotes - in insect
• amastigotes - in tissue

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Chagas' disease

• Clinical features
• Incubation period 5-14 days up to 40 by
  transfusion
• Symptoms
• Acute
• variable fever, malaise, lymphadenopathy,
  hepatomegaly
• chagoma inflammatory response at site of
  infection may last a couple of months
• Romaña sign bipalpebral edema (unilateral)

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Chagas' disease

• Clinical features
• Symptoms
• Chronic - irreversible sequelae including
• cardiovascular cardiomyopathy, arrythmias,
  conduction disturbances
• gastrointestinal megaesophagus, megacolon
• meningoencephalitis in AIDS patients

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Chagas' disease

• Diagnosis
• Demonstration of the agent is the diagnostic
  procedure in acute Chagas'' disease almost
  always yields positive results
• Microscopic examination
• a) of fresh anticoagulated blood, or its buffy
  coat, for motile parasites
• b) of thin and thick blood smears stained with
  Giemsa, for visualization of parasites.

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Chagas' disease

• Diagnosis
• Demonstration of the causal agent
• Isolation
• a) inoculation into mice
• b) culture in specialized media (e.g., NNN, LIT)
• c) xenodiagnosis, where uninfected reduviid bugs
  are fed on the patient's blood, and their gut
  contents examined for parasites 4 weeks later.

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Chagas' disease

• Diagnosis
• Serology - antibody detection or antigen
  detection useful in screening and for chronic
  infections
• IFA
• EIA
• PCR

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Chagas' disease

• Treatment
• nifurtimox - for acute cases
• benznidazole - also effective in acute cases

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Chagas' disease

• Prevention and control
• Education
• Vector and reservoir control
• Screeing of blood and organ donors