American Trypanosomiasis (Chagas Disease)

S
l
i
d American Trypanosomiasis
e
Chagas Disease
New World Trypanosomiasis
South American Trypanosomiasis
1 Mal de Chagas
Chagas-Mazza Disease

S In today’s presentation we will cover information regarding the organism

l Overview that causes Chagas disease and its epidemiology. We will also talk about
i • Organism the history of the disease, how it is transmitted, species that it affects
d • History (including humans), and clinical and necropsy signs observed. Finally, we
• Epidemiology will address prevention and control measures for Chagas disease, as well
e • Transmission
as actions to take if Chagas disease is suspected.
• Disease in Humans
2 • Disease in Animals
• Prevention and Control
• Actions to Take
Center for Food Security and Public Health, Iowa State University, 2012

S
l
i
d
e ORGANISM

S American trypanosomiasis (Chagas disease) results from infection with

l The Organism the protozoan parasite Trypanosoma cruzi, a member of the family
i • Protozoan parasite Trypanosomatidae. Most strains of this parasite can be classified into two
– Trypanosoma cruzi major groups, T. cruzi I and T. cruzi II, which can be separated further
d
• Cause of American
e trypanosomiasis
into various lineages (e.g., T. cruzi IIa). Lineages tend to be associated
(Chagas disease) with certain host species, although this relationship is not absolute. T.
• Susceptible to: cruzi is susceptible to many disinfectants. It is destroyed by several hours
4 – Disinfectants, direct sunlight,
other harsh environments of exposure to direct sunlight or other harsh environments.
Center for Food Security and Public Health, Iowa State University, 2012

[Photo: Trypanosoma forms in blood smear from patient with African

trypanosomiasis. Source: CDC Public Health Image Library]

S
l
i
d
e HISTORY

Center for Food Security and Public Health 2012 1

American Trypanosomiasis (Chagas Disease)

S In 1907, while working among railroad workers in Brazil, physician

l History of Chagas Carlos Chagas first became aware of the barbiero, a blood-sucking bug
i • 1907: Dr. Carlos Chagas infesting huts of the region. He quickly became interested in the insect
first becomes aware and investigated whether it could be a transmitter of any parasites of man.
d of the barbiero
e • 1909: First publications
By 1909, a new species of trypanosome was discovered, and the first
on newly discovered published reports followed. Until the 1930s, little attention was given to
trypanosome Chagas disease as a public health issue.
6 • 1930s: Public health
importance becomes
known Source: R. Lewinsohn. Carlos Chagas and the discovery of Chagas'
Center for Food Security and Public Health, Iowa State University, 2012

disease (American trypanosomiasis). J R Soc Med. 1981 June; 74(6):

451–455.

[Photo: Carlos Chagas. Source: J. Pinto/Biblioteca Virtual Carlos Chagas

via wikipedia.org]

S
l
i
d
e EPIDEMIOLOGY

S T. cruzi can be found in the Americas from the U.S. to Chile and central
l Geographic Distribution Argentina. In the U.S., this parasite is thought to be endemic in
i • Americas approximately the southern half of the country, as well as in California.
– South America An estimated 8 to 11 million people are infected worldwide.
d – Central America
e • United States
– Endemic in Southern
half and California
8 • 8 to 11 million people
infected worldwide

Center for Food Security and Public Health, Iowa State University, 2012

S Chagas disease is most common among people who live in substandard

l Populations at Risk housing in developing areas. Triatomine vectors for T. cruzi are present in
i • Neglected Infection of Poverty (NIP) the U.S.; however, only a few locally acquired, vector-borne cases have
– Disproportionately affects been diagnosed in people. The lower prevalence rate in the U.S. is mainly
d impoverished people in the U.S.
e • Occupational groups
due to higher standards of living and the absence of triatomine species
– Veterinarians, laboratory personnel that are well adapted to living in human houses. According to the CDC,
• Wildlife handlers Chagas is considered a Neglected Infection of Poverty (NIP) in the U.S.
9 • Hunters
since it is found mostly in those with limited resources and limited access
• Travelers to endemic areas
to medical care. People in certain occupational risk groups may also be
Center for Food Security and Public Health, Iowa State University, 2012

exposed; this includes veterinarians, technicians, and laboratory

personnel. Individuals who work with wildlife and hunters are at risk, as
are travelers to areas where Chagas is endemic.

Center for Food Security and Public Health 2012 2

American Trypanosomiasis (Chagas Disease)

S Trypanosoma cruzi occurs in more than 100 species of mammals

l Species Affected throughout the Americas; infections have been reported among carnivores
i • Many mammals in the Americas including dogs and cats, as well as in pigs, goats, lagomorphs, rodents,
d • Frequent hosts in the U.S. marsupials, bats, xenarthra (anteaters, armadillos and sloths) and non-
– Opossums
e human primates. In the U.S., opossums, armadillos, raccoons, coyotes,
– Armadillos
– Raccoons rats, mice, squirrels, dogs and cats are among the most frequent hosts.
– Coyotes Birds, reptiles and fish are not susceptible to infection.
1 – Rats, mice, squirrels
[Photos: (Top) Raccoon, (Bottom) Opossum. Source: U.S. Fish and
0 – Dogs
– Cats Wildlife Service National Digital Library]
Center for Food Security and Public Health, Iowa State University, 2012

S
l
i
d
e TRANSMISSION

1
1

S Chagas disease is a vector-borne disease transmitted primarily by

l Transmission triatomine insects, which are also called reduviid insects, “kissing beetles/
i • Vector-borne bugs” or “assassin bugs.” More than 130 species of these insects appear
– Triatomine insects to be capable of transmitting T. cruzi, with the most important species in
d • Reduviid insects,
e kissing beetle/bug, the genera Triatoma, Rhodnius and Panstrongylus. The parasite usually
assassin bug
– Multiple species
completes its life cycle by cycling between an insect species and a
capable of transmission mammalian species with which the insect lives in close association.
1 • Triatoma
• Rhodnius [Photo: Dorsal view of the “kissing bug”, Triatoma infestans, a vector for
2 • Panstrongylus
Chagas disease. Source: CDC Public Health Image Library]
Center for Food Security and Public Health, Iowa State University, 2012

S There are three basic cycles of transmission for T. cruzi. In the sylvatic
l Transmission (wild) cycle, this organism cycles between wildlife and triatomine insects
i • Three transmission cycles that live in sylvatic environments. Humans and domesticated animals are
– Sylvatic (wild) infected occasionally when they contact these bugs in the wild. The
d • Wildlife-insect transmission
e • Human infections rare sylvatic cycle is responsible for relatively few cases of Chagas disease. It
– Domestic is the only cycle in the U.S. A domestic transmission cycle also exists in
• Human-insect transmission

1 – Peridomestic Mexico and parts of Central and South America. In this cycle, some
• Transmitted via: insect vectors have colonized primitive adobe, grass and thatched houses,
3 – Blood, organs, ingestion, in utero, milk
resulting in transmission between humans and insects. Transmission
Center for Food Security and Public Health, Iowa State University, 2012

cycles between insects and domesticated animals (peridomestic cycles)

can also provide opportunities for the parasite to infect humans. T. cruzi
is not spread between mammals by casual contact; however, it can be
transmitted directly via blood (e.g., in a blood transfusion) and in donated
organs. Carnivores can acquire this organism when they eat infected prey.
Vertical transmission has been reported in dogs and other animals, both in
utero and in the milk. Transmission in milk is very rare in humans, but
transplacental transmission can occur at each pregnancy, and during all
stages of infection. Laboratory infections usually occur when the
parasites contact mucous membranes or broken skin, or are accidentally
injected via needlestick injuries, but aerosol transmission might be
possible in this setting. [Photo: House with Chagas disease vectors.
Source: Pan American Health Organization]

Center for Food Security and Public Health 2012 3

American Trypanosomiasis (Chagas Disease)

S This figure, from the CDC

l [http://www.cdc.gov/parasites/chagas/biology.html], shows how Chagas
i is transmitted. An infected triatomine insect vector (or "kissing" bug)
d takes a blood meal and releases trypomastigotes in its feces near the site
e of the bite wound. Inside the host, they differentiate into other forms, and
are released into the bloodstream. Cells from a variety of tissues can be
1 infected. Replication resumes only when the parasites enter another cell
or are ingested by another vector. The “kissing” bug becomes infected by
4
feeding on human or animal blood that contains circulating parasites.
Center for Food Security and Public Health, Iowa State University, 2012

S
l
i
d
e DISEASE IN HUMANS

1
5

S In humans, the incubation period is usually at least 5 to 14 days after

l Chagas Disease exposure to triatomine insect feces, and 20 to 40 days after infection by
i • Incubation period blood transfusion. Many people do not become symptomatic until the
– 5 to 14 days after exposure chronic stage, which can occur 5 to 40 years after infection.
d to triatomine insect feces
e – 20 to 40 days after blood transfusion
– 5 to 40 years after infection
• Chronic stage
1
6
Center for Food Security and Public Health, Iowa State University, 2012

S The acute phase is defined as the period during which the parasites can be
l Chagas Disease found easily in the blood. Many people, particularly adults, are
i • Acute phase asymptomatic during this stage. The symptoms of the acute phase are
– Parasites found in blood highly variable and may include fever, headache, anorexia, malaise,
d – Most adults asymptomatic
e – Chagoma
myalgia, joint pain, weakness, nausea, vomiting, diarrhea, hepatomegaly,
• Localized painless induration splenomegaly, and generalized or localized lymphadenopathy. Edema,
– Romaña’s sign
1 • Edema of eyes, conjunctivitis
either generalized or localized to the face and/or lower extremities, occurs
• Usually resolves in weeks to months in some cases. Sometimes, a chagoma (a localized painless induration) is
7
seen where the parasite has entered through the skin. If entry occurs via
Center for Food Security and Public Health, Iowa State University, 2012

the ocular mucous membranes, there may be painless edema of one or

occasionally both eyes, often accompanied by conjunctivitis and
enlargement of the local lymph nodes. This syndrome, which is called
Romaña’s sign, usually persists for 1 to 2 months. Patients occasionally
develop a rash, but this usually disappears within several days. In most
cases, the clinical signs resolve within weeks to months without
treatment; however, some acute cases can be fatal.

[Photo: This child from Panama is suffering from Chagas disease

manifested as an acute infection with swelling of the right eye. Source:
CDC Public Health Image Library]

Center for Food Security and Public Health 2012 4

American Trypanosomiasis (Chagas Disease)

S The acute phase is usually followed by an asymptomatic period of

l Chagas Disease varying length; this stage is called the indeterminate phase. During the
i • Indeterminate phase indeterminate phase, the parasites disappear from the blood. Although
– Asymptomatic phase of varying length estimates vary, approximately 70% to 90% of the patients in the
d – Parasites disappear from blood
e – Most patients enter chronic phase
indeterminate phase never become symptomatic. Most of the remaining
within 5 to 15 years patients enter the chronic phase after 5 to 15 years, but in a few patients,
1 the indeterminate phase can last as long as 40 years.
8
Center for Food Security and Public Health, Iowa State University, 2012

S The chronic phase is typically represented by organ failure, usually of the

l Chagas Disease heart or digestive system. Heart disease, the most common form of
i • Chronic phase chronic Chagas disease, may be characterized by arrhythmias and
– Characterized by organ failure conduction abnormalities, cardiac failure, apical aneurisms, embolic
d
• Heart disease
e disease including stroke or pulmonary embolism, and sudden death. Signs
– Most common form of chronic Chagas
– Many manifestations may occur of isolated left heart failure may occur first. Digestive system
• Digestive system abnormalities abnormalities lead to megaesophagus and/or megacolon, which can occur
1 – Megaesophagus
concurrently with heart disease. The symptoms of megaesophagus may
9 – Megacolon
include pain during swallowing, excessive salivation, regurgitation and
Center for Food Security and Public Health, Iowa State University, 2012

chest pain. In severe cases, there may be weight loss or cachexia, and the
esophagus may rupture. The symptoms of megacolon include severe
constipation, which can last for a few days to months, and abdominal pain
that is often associated with episodes of constipation. Patients with
Chagas disease also have an increased chance of developing gastric ulcers
or chronic gastritis, due to abnormalities in the stomach.

S Women who are infected with T. cruzi can give birth to infected children.
l Chagas Disease Congenital infections may occur during any of the woman’s pregnancies,
i • Immunocompromised people can be whether she is symptomatic or not. In congenitally infected infants, the
severely affected most common symptoms are premature birth, hepatosplenomegaly,
d
• Pregnant women
e – Congenital infection,
meningoencephalitis, changes in the retina and signs of acute
premature birth myocarditis/ cardiac insufficiency. Transplacental infections are also
• AIDS patients associated with abortions. Patients with AIDS suffer a more severe form
2 – Brain abscesses
– Higher likelihood of reactivation
of the disease with a high percentage of neurological and cardiac signs.
0
Many of these patients develop T. cruzi brain abscesses, which are not
Center for Food Security and Public Health, Iowa State University, 2012

seen in immunocompetent patients. HIV-infected individuals and others

who are immunosuppressed, including those who receive organ
transplants, are at risk for reactivation of T. cruzi replication.

[Photo: Mother and infant. Sourcee: Pan American Health Organization]

S Chagas disease can be diagnosed by microscopy, isolation of the parasite,

l Diagnosis serology or molecular techniques. Light microscopy can sometimes detect
i • Microscopy T. cruzi in Giemsa or Wright stained samples of blood, cerebrospinal
– Blood, CSF, tissues fluid or tissues. T. cruzi can be found in the heart, skeletal and smooth
d – Acute stage
e • Parasite isolation
muscle cells, and the glial cells of the nervous system. It sometimes
• Serology occurs in chagomas. In immuno-compromised patients, parasites may
2 – Indirect immunofluorescence, ELISA also be detected in atypical sites such as the pericardial fluid, bone
– Chronic stage
marrow, brain, skin and lymph nodes. Active parasitemia is much more
1 • Molecular techniques
likely to be found during the acute than the chronic stage. T. cruzi can be
Center for Food Security and Public Health, Iowa State University, 2012

cultured from heparinized blood samples or tissues. Various specialized

media including liver infusion tryptose medium or Novy-MacNeal-
Nicolle medium, as well as Vero cell lines can be used. Culture may take

Center for Food Security and Public Health 2012 5

American Trypanosomiasis (Chagas Disease)

1 to 6 months. Serology is most often used to diagnose chronic infections.

Commonly used serological tests in humans include indirect
immunofluorescence (IFA), hemagglutination and enzyme-linked
immunosorbent assays (ELISAs). Other tests including
radioimmunoprecipitation and complement fixation may also be used.
Cross-reactions can occur with other parasites, particularly Leishmania
species. Polymerase chain reaction (PCR) techniques can be used for
diagnosis. Immunoblotting (Western blotting) is another option.

[Photo: Micrograph of Trypanosoma cruzi in a blood smear using Giemsa

staining technique. CDC Public Health Image Library]

S Acute Chagas disease can be treated with antiparasitic drugs. In the U.S.,
l Treatment drugs may be available only under an Investigational New Drug protocol
i • Antiparasitic drugs from the CDC Drug Service. Treatment of acute or congenital cases is
– Treat acute or congenital cases recommended to prevent the development of chronic disease.
d to prevent chronic disease
e – Administer long term Antiparasitic drugs are less effective in the indeterminate and chronic
– Significant side effects stages, and treatment recommendations may vary with the age of the
• Chronic stage patient and other factors. There are significant side effects with these
2 – Symptomatic treatment of cardiac
and digestion disease drugs, which must be given long term. In the chronic stage, treatment of
2
cardiomyopathy is mainly symptomatic and similar to the treatment of
Center for Food Security and Public Health, Iowa State University, 2012

other causes of heart disease. A pacemaker may be necessary, and a heart

transplant can be considered. Surgery, balloon dilation of the
gastroesophageal junction and/or symptomatic relief may be used for
chagasic megaesophagus or megacolon.

S The morbidity and mortality rates vary with the stage of the disease.
l Morbidity and Mortality Approximately 5% of people infected with T. cruzi develop acute
i • Acute symptoms: 5% symptoms. Estimates of the case fatality rate for acute Chagas disease
d • Case fatality rate: 5 to 8% range from less than 5% to approximately 8%; among immunologically
– Deaths mostly in children
e – Acute myocarditis, meningoencephalitis
competent individuals; deaths occur mainly in young children with acute
• Chronic disease: 20 to 30% myocarditis or meningoencephalitis. The CDC estimates that 20 to 30%
2 – Exact causes for disease of humans infected with T. cruzi eventually develop chronic disease;
progression unknown
estimates from other sources vary from 10% to 50%. The reason for the
3
progression of disease in some patients but not others is unknown. It may
Center for Food Security and Public Health, Iowa State University, 2012

be related to host genetic factors, the dose of the parasites, the number of
inoculations, the strain of the parasite, and immunological or nutritional
factors. Cardiac disease is often fatal. Occasionally, deaths are also
caused by volvulus of a dilated sigmoid megacolon.

S
l
i
d
e DISEASE IN ANIMALS

2
4

Center for Food Security and Public Health 2012 6

American Trypanosomiasis (Chagas Disease)

S The incubation period for acute disease in dogs appears to be 5 to 42

l Disease in Animals days; in experimental infections, symptoms of acute heart disease are
i • Incubation usually reported after 2 to 4 weeks. Like humans, some dogs may not
– Dogs: 5 to 42 days develop clinical signs until the chronic stage, which occurs after a few
d – May be asymptomatic until chronic
e stage years later years; the exact length of this period is not known. Trypanosoma cruzi
• Hosts occurs in more than 100 species of mammals throughout the Americas;
– Dogs, cats commonly affected dogs and cats are commonly affected. Birds, reptiles, and fish are not
2 – Birds, reptiles, fish not susceptible
susceptible.
5
Center for Food Security and Public Health, Iowa State University, 2012

S Acute, latent and chronic stages of infection occur in experimentally

l Clinical Signs: Dogs infected dogs. Clinical signs reported in the acute stage include fever,
i • Acute phase anorexia, lethargy, an unkempt hair coat, lymphadenopathy,
– Lymphadenopathy, ataxia, hepatomegaly and splenomegaly. Anorexia, diarrhea, ascites and/or
d diarrhea, weakness
e – Acute myocarditis develops weight loss may also be seen. Cardiac dysfunction can occur during the
2 to 3 weeks post-infection acute phase; acute myocarditis may cause arrhythmias or sudden collapse
• Chronic phase
2 – Congestive heart failure,
and death. After the acute phase, infected dogs enter the indeterminate
cardiac dilatation, sudden (latent) stage, during which the parasites are difficult to find and the
6 death
animal is asymptomatic. The indeterminate stage can be as short as 27
Center for Food Security and Public Health, Iowa State University, 2012

days in some experimentally infected animals, but it seems to last for

years in some natural infections. Congestive heart failure is the most
common sign during the chronic stage. Right-sided heart failure usually
occurs first. Eventually, dogs with heart disease develop chronic
myocarditis with cardiac dilatation and arrhythmias. Sudden death can
occur. [Photo: Dog. Source: AVMA Press Room Photo Gallery]
S Symptomatic Chagas disease has been rarely described in cats. Reported
l Disease in Other Species clinical signs include fever, edema, weight loss and neurological signs
i • Cats such as convulsions and paresis. There is little information about Chagas
– Usually asymptomatic disease in other species, including wild animals. Mild, histologically
d – Rarely fever, edema, weight loss,
e neurological signs evident myocarditis (without clinical signs of heart disease) has been
• Other species reported at necropsy in infected wild raccoons and opossums. Naturally
– Mostly unknown infected rats can develop arrhythmias and more severe cardiac lesions.
2 – Myocarditis reported in wildlife
– Cardiac, reproductive disease in Infertility, fetal losses, reduced birth weights, and early postnatal deaths
7 rats and mice have been reported in pregnant mice.
Center for Food Security and Public Health, Iowa State University, 2012

S In dogs, acute disease is characterized mainly by cardiac lesions, which

l Post Mortem Lesions are particularly prominent on the right side. The myocardium may be
i • Right side cardiac pale, and subendocardial and subepicardial hemorrhages are often
lesions present. Multiple yellowish-white spots and streaks, mainly involving the
d – Dilation, hemorrhages,
e paleness, pericardial coronary groove, may be found in the heart. In addition, there may be
effusion secondary pulmonary edema, congestion in the liver, spleen and kidneys,
• Pulmonary edema
2 • Peritoneal transudate
and a modified transudate in the peritoneal cavity. Pericardial effusion
– Liver, spleen, kidney has been reported in some naturally infected dogs. Gross lesions may be
8 congestion
absent in some infected animals. In chronic Chagas disease, the heart is
Center for Food Security and Public Health, Iowa State University, 2012

bilaterally enlarged and flaccid, with thinning of areas in the ventricular

walls. Atypical cases without cardiac lesions have also been reported.

[Photo: Dog, heart. There are multiple white linear streaks on the surface
of the right and left ventricles corresponding to myocardial necrosis and
myocarditis. Source: Dr. S. Barr, Cornell University, College of
Veterinary Medicine, Department of Clinical Sciences/CFSPH]

Center for Food Security and Public Health 2012 7

American Trypanosomiasis (Chagas Disease)

S Chagas disease can be diagnosed by microscopy, isolation of the parasite,

l Diagnosis and Treatment serology and molecular techniques. A presumptive diagnosis can be made
i • Diagnosis if T. cruzi is observed by light microscopy in a stained blood smear or
– Microscopy buffy coat sample, or in tissues such as the heart. T. cruzi can be cultured
d – Parasite isolation
e – Serology
from blood samples or tissues; culture is usually more successful in the
• Indirect immunofluorescence acute stage. This organism often occurs in the myocardium, but it can
– Molecular techniques
2 also be isolated from other organs such as the lymph nodes, liver,
• Treatment
– Antiparasitic drugs gastrointestinal tract, brain, cerebrospinal fluid and adrenal gland.
9
Various specialized media including liver infusion tryptose medium or
Center for Food Security and Public Health, Iowa State University, 2012

Novy-MacNeal-Nicolle medium, as well as Vero cell lines may be used.

Indirect immunofluorescence is the most commonly used serological test.
Other assays include radio-immuno-precipitation, direct and indirect
hemagglutination, complement fixation and ELISAs. Cross-reactions can
occur with other parasites, particularly Leishmania species. Molecular
detection methods including PCR and western blot (immunoblot) analysis
techniques can detect T. cruzi DNA in tissues and blood. Occasionally,
dogs have been treated with anti-parasitic drugs. These drugs appear to be
more effective in the early stages; by the time of diagnosis, treatment may
be too late to prevent the progression of the disease.

S The prevalence rate can be high among wildlife in endemic areas.

l Morbidity and Mortality Surveys of wildlife in the U.S., conducted mainly in raccoons and
i • Prevalence in wildlife opossums, have reported prevalence rates from 2% to 62%. In the U.S.,
– 2 to 62% in raccoons and opossums the reported seroprevalence rates in dogs from Texas, Oklahoma,
d
• Prevalence in dogs
e – 1.1 to 8.8% (U.S.)
Louisiana, Georgia and other southern states vary from 1.1% to 8.8%.
– 10 to 17% (Mexico) Over a 15-year period, more than 500 clinical cases of Chagas disease
• Mortality were reported among dogs in Texas, suggesting that this disease occurs
3 – High in experimentally infected animals
regularly in some areas. In the Yucatan region of Mexico, one study
0
reported that 10-14% of dogs were seropositive, but when both serology
Center for Food Security and Public Health, Iowa State University, 2012

and PCR were used, the prevalence as high as 17%. The infection rate is
highest among dogs that are regularly exposed to wildlife and insect
vectors. Cats are frequently infected with T. cruzi in South America.
There is little information on the morbidity and mortality rates in dogs,
except in experimentally infected animals, where these rates are high.
Based on human data, some sources suggest that approximately 5% of
naturally infected animals would be expected to develop symptoms
during the acute stage. In naturally infected dogs with chronic cardiac
disease, the survival time after diagnosis ranged from 0 months to 5
years.

S
l
i
d
e PREVENTION AND
CONTROL

3
1

Center for Food Security and Public Health 2012 8

American Trypanosomiasis (Chagas Disease)

S Currently, states are not required by federal law to report cases of Chagas
l Recommended Actions disease. However, Chagas disease is reportable by state mandate in
i • Chagas is NOT a nationally Arizona, Massachusetts, and Tennessee. At this time, there are no plans to
notifiable disease add Chagas disease to the list of diseases which are nationally notifiable.
d
• Reportable by state mandate in:
e – Arizona
– Massachusetts
– Tennessee
3
2
Center for Food Security and Public Health, Iowa State University, 2012

S Contact with triatomine insects should be prevented; they usually feed at

l Prevention in Humans night and withdraw to their hiding places in daylight. In endemic areas,
i • Prevent contact with triatomine houses can be improved by plastering walls, improving flooring and
insects and their feces taking other measures to remove the cracks where these insects hide.
d – Improve substandard housing
e – Use screens/bed nets when sleeping
Triatomine insects are often found in basements, which should be
– Spray homes with avoided. Sleeping inside a screened area, under a permethrin-impregnated
insecticides
3 – Cook contaminated
bed net, or in an air-conditioned room is safest. Bed nets should be tucked
foods tightly under the mattress before dusk. Animal pens and storage areas
3
should be kept away from homes. Regular spraying of insecticides in and
Center for Food Security and Public Health, Iowa State University, 2012

around houses can reduce the number of insects, and in some cases,
eliminate them. Foods that might be contaminated should be cooked.
Since 1991, the Pan American Health Organization and the World Health
Organization have run a joint program to eliminate T. infestans, the most
important vector for Chagas disease in humans. This program has
decreased the distribution of this insect by more than 80%, although foci
can still be found in some regions. [Photo: Personnel applying
insecticides in infested household. Source: Pan American Health
Organization]
S Blood and organ donors should be screened to prevent transmission by
l Prevention in Humans these routes. In the U.S., transfused blood has been screened for Chagas
i • Screen blood and organ donors disease since 2007. Pregnant women can be tested to identify cases where
d • Occupational risk groups congenital transmission may occur, and the infant should be monitored
– Wear gloves, other PPE
e and treated if necessary. People in occupational risk groups should take
– Dispose of sharps properly
• Travelers additional precautions. Veterinarians and technicians should protect their
3 – Wear thick clothing skin and mucous membranes from contamination with parasites in blood
– Avoid substandard housing
or tissues. This includes using gloves and/or other barriers while drawing
4 • Vaccine not available
blood samples from T. cruzi-infected animals, taking care of IV catheters
Center for Food Security and Public Health, Iowa State University, 2012

or performing other invasive procedures. Needles and other “sharps”

must be handled and disposed of properly to prevent needlestick injuries.
Individuals who work with wildlife and hunters should also take
precautions, especially when handling blood and tissues. Laboratory
personnel should use appropriate personal protective equipment,
including gloves and eye protection, while processing blood samples,
cultures or infected insects. If an accidental exposure occurs, the site
should be disinfected immediately if possible, and antiparasitic drugs may
be given prophylactically. Travelers to areas where Chagas disease is
common should wear thick clothing that covers as much of the body as
possible; heavy long-sleeved shirts, long pants, socks and shoes are
recommended. Sleeping in sub-standard housing should, if possible, be
avoided. Vaccines are not available for humans; however, precautions can
be taken to reduce the risk of infection, particularly in countries where the
prevalence of Chagas disease is high.

Center for Food Security and Public Health 2012 9

American Trypanosomiasis (Chagas Disease)

S Dogs and cats should not be allowed to eat tissues from potentially
l Prevention in Animals infected wild animals. Strict indoor housing in well-constructed homes or
i • Keep pets away from tissues of other facilities reduces the risk of infection. Housing animals indoors at
wild animals night, when triatomine insects are active, may also be helpful. Residual
d
• Indoor housing
e – Especially at
insecticides sprayed regularly in kennels and surrounding structures may
night decrease the number of insect vectors. In breeding kennels, testing bitches
• Pest control in for T. cruzi-might also decrease the incidence of Chagas disease by
3 kennels
• Test dogs
reducing vertical transmission. No vaccines are available.
5
Center for Food Security and Public Health, Iowa State University, 2012

[Photo: Indoor dog kennel. Source: USDA APHIS Image Gallery]

S
l Additional Resources
i • Center for Food Security and Public Health
– www.cfsph.iastate.edu
d • CDC: American Trypanosomiasis/
Chagas Disease
e – http://www.cdc.gov/parasites/chagas/
• World Health Organization: Chagas Disease
– http://www.who.int/topics/chagas_disease/en/
3 • Pan American Health Organization
– http://www.paho.org/english/ad/dpc/cd/chagas.htm
6
Center for Food Security and Public Health, Iowa State University, 2012

S Last updated: February 2012

l Acknowledgments
i Development of this presentation was made possible
through grants provided to
d the Center for Food Security and Public Health at Iowa
State University, College of Veterinary Medicine from
e the Centers for Disease Control and Prevention,
the U.S. Department of Agriculture,
the Iowa Homeland Security and
Emergency Management Division, and the
Multi-State Partnership for Security in Agriculture.
3
7 Authors: Kerry Leedom Larson, DVM, MPH, PhD, DACVPM; Anna Rovid Spickler, DVM,
PhD; Sarah Viera, MPH
Reviewer: Glenda Dvorak, DVM, MPH, DACVPM

Center for Food Security and Public Health, Iowa State University, 2012

Center for Food Security and Public Health 2012 10