Chagas: experts warn of "silent killer"

[Gert van der Hoek]

Disease experts warn of 'silent killer'

Parasites can damage heart tissue, nerve cells

By Sharon Kirkey, CanWest News Service

Published: Sunday, June 10, 2007

Tropical disease experts are warning of a new threat to Canada's blood supply, a "silent killer" that produces no symptoms for years while parasites slowly feed on a person's heart muscle and intestines.

Chagas disease is endemic in parts of Central and South America where it has already infected up to 20 million people and kills more than 50,000 every year.

Transmitted by blood-sucking "assassin" bugs, Chagas - named after the Brazilian doctor, Carlos Chagas, who discovered it in 1909 - can also be spread via infected blood transfusions.

Now, the parasitic infection is drifting northward because of immigration patterns and travel - including adventure and eco-tourists to such Chagas-hit areas as Colombia and parts of Brazil.

Chagas isn't a reportable illness in Canada; its prevalence is unknown. What's more, front-line doctors may know about West Nile virus or Lyme disease, but most would not know Chagas to see it, experts say. "I don't think the average primary care doc would know it [at] all," says Dr. Jay Keystone, professor of medicine at the University of Toronto.

It can take 20 years or longer for the parasite to cause sufficient damage to nerve cells and tissue in the heart to put people into heart failure. People can have strokes because of heart arrhythmias.

The disease can attack in other ways: Researchers recently reported the case of a 40-year-old man who was transferred to hospital from a Manitoba jail after a two-week history of headache, nausea, vomiting and drowsiness.

A CT scan showed what appeared to be a brain tumour; a biopsy revealed a huge abscess in his frontal lobes that, under the microscope, turned out to be related to the organism, Trypanosoma cruzi, or T. cruzi, which causes Chagas.

"Normally people get this in South and Central America, and to the knowledge of everybody who knew this fellow, he had never travelled to those areas," said Dr. Marc Del Bigio of the University of Manitoba's department of pathology.

The Canadian Blood Services told CanWest News Service it is preparing to screen the nation's blood supply for Chagas.

But just how extensively to test, what test to use and when testing should start have not been decided.

"We've been watching this Chagas for a long time," said Dana Devine, vice-president of medical, scientific and research affairs.

Two cases of blood-transmitted Chagas have been reported in Canada, in 1986 and 2000. Both donors were from the same Mennonite community in Winnipeg and had lived in South America.
The clinic where they gave blood has been closed. "We no longer collect blood in that area," Ms. Devine said.

She said the risk of blood-transmitted Chagas is believed to be "really very low" but "no one really understands what the scope of the problem may or may not be for blood systems in North America.

Dr. Keystone and other experts believe it is likely other transmissions via infected blood transfusions have occurred but gone unrecognized.

"It's a silent killer," said Dr. Keystone. "If somebody comes to you with heart failure, you would say, Oh, you probably have coronary artery disease.' He'd send you to a cardiologist."

Chagas can be curable in the acute phase, if caught early. "But once you're in the latent phase and develop heart problems, it may not be curable," he said.

http://www.canada.com/nationalpost/n...d50dec8afe&k=0

[Gert van der Hoek]

Re: Chagas: experts warn of "silent killer"

US Doctors Find More Cases of Parasite Infections

By Carol Pearson

Washington

22 May 2007

Doctors in the United States are seeing more infections from parasites normally found in developing countries. These infections could be prevented, contained or cured, but the problem is, many American doctors are not trained to look for signs of parasite infections until sometimes it is too late. VOA's Carol Pearson reports.


Chagas disease is one example of the parasitic infections doctors in the U.S. are now seeing. It is caused by a microscopic parasite, called T. cruzi. Dr. James Maguire, Director, International health division, University of Maryland shows the bug that causes Chagas disease.

Dr. Maguire specializes in diseases caused by parasites. Chagas disease can cause severe chronic illness or death.

Los Angeles Public Health Director Jonathan Fielding says donated blood tainted by T. cruzi is starting to show up in hospital operating rooms. "There have been two cases locally where somebody has gotten an organ transplant and found out that organ was infected with Chagas disease and they've developed Chagas disease."

Once in the body, the parasites literally feed off organ cells such as those in the heart. As they multiply, the cells burst. If the parasites are in the heart, the infected person can experience sudden heart failure. Dr. Maguire says what the blood banks in Los Angeles are finding is only part of the picture. "That's probably the tip of the iceberg. There may be as much as ten times as many people who are infected, and we don't know about that. "

Most people in the U.S. with Chagas disease are immigrants from Mexico, Central and South America. Dr. Maguire says Chagas disease is difficult to cure and easy to miss during a physical examination.

"Most people wouldn't know unless they had a blood test." Reporter: "And the doctor would have to be looking for it." Dr. Maguire nods and adds, "...would have to be looking for it and would have to be knowledgeable about the disease."

Dr. Maguire says about half of the blood banks in the United States screen donors for this parasite.

(snip)

http://www.voanews.com/english/2007-05-22-voa39.cfm

[Gert van der Hoek]

Re: Chagas: experts warn of "silent killer"

Chagas: Disease information

Distribution

18 countries in 2 ecological zones:

Southern Cone, where vector insects live inside human homes

Northern South America, Central America and Mexico, where the vector lives both inside and outside dwellings


Causative agent

The protozoan parasite (Trypanosoma cruzi), which enters the human body though broken skin

Transmission

Parasites are transmitted to humans in 3 ways

1) By bloodfeeding "Assassin bugs’ (sub-family Triatominae), which live in cracks and crevices of poor-quality houses, usually in rural areas. They emerge at night to bite and suck blood. The faeces of the insects contain parasites which can enter the wound left after the bloodmeal, usually when it is scratched or rubbed

2) Through transfusion with infected blood

3) Congenitally, from infected mother to foetus


Symptoms

Usually a small sore develops at the bite where the parasite enters the body. If this is near the eye, the eyelid becomes swollen (known as Romaña’s sign). Within a few days, fever and swollen lymph nodes may develop.

This initial acute phase may cause illness and death, especially in young children. More commonly, patients enter a symptomless phase lasting several months or years, during which time parasites are invading most organs of the body, often causing heart, intestinal and oesophageal damage and progressive weakness.

In 32% of those infected, fatal damage to the heart and digestive tract occurs during this chronic phase.

Prevention and control

1) Treatment of homes with residual insecticides

2) Blood screening to prevent transmission through transfusion

3) Drug treatment for acute early indeterminate and congenital cases

4) House improvement (substituting plastered walls and a metal roof for adobe-walled, thatch-roofed dwellings).


For therapy, two drugs (nifurtimox and benznidazole) can be used for the early chronic phase.

T. cruzi antigens can stimulate autoimmunity, so the prospects for an effective vaccine are slim.

Control relies on killing vector insects in houses, improving housing to render them unsuitable for colonization by vector insects, and comprehensive health education initiatives.

Travellers can avoid the disease by not sleeping in infested housing and ensuring that any transfusions are with blood that have been screened.

http://www.who.int/tdr/diseases/chagas/diseaseinfo.htm

[Jonesie]

Re: Chagas: experts warn of "silent killer"

Chagas' Disease
(American Trypanosomiasis)


Diagnosis

The number of trypanosomes in peripheral blood is high during the acute phase and readily detected by examination of thin or thick smears. In contrast, few parasites are present in blood during latent infection or chronic disease. Definitive diagnosis may be made by examination of aspirates from organs such as lymph nodes. Serologic tests are sensitive but may yield false-positive results in patients with visceral or mucocutaneous leishmaniasis or other diseases. Other diagnostic approaches include xenodiagnosis (by examining the rectal contents of laboratory-raised bugs after they take a blood meal from a suspected patient) and detecting PCR-amplified parasite DNA in blood or tissue fluids.

Treatment and Prevention

Treatment in the acute stage rapidly reduces parasitemia, shortens the clinical illness, and reduces risk of mortality but often does not eradicate the infection. Treatment of children and young adults with indeterminate infections has been recommended, but many are not cured. Treatment in the chronic stage is symptomatic. Chronic organ damage, which may be caused in part by host inflammatory responses, appears to be largely irreversible. Supportive measures include drugs for heart failure, pacemakers, antiarrhythmic drugs, cardiac transplantation, esophageal dilation, and GI tract surgery.

The only effective drugs are nifurtimox (2 to 2.5 mg/kg po qid for 3 to 4 mo in adults; 4 to 5 mg/kg qid for 3 mo in 1- to 10-yr-old children; 3 to 3.75 mg/kg qid for 3 mo in 11- to 16-yr-old children) or benznidazole (2.5 to 3.5 mg/kg po bid for 1 to 3 mo for adults; 5.0 mg/kg bid for children ≤ 12 yr). These long treatment courses are often associated with severe GI adverse effects, peripheral neuropathy, poor tolerance, and low compliance.

Plastering walls and replacing thatched roofs or repeated spraying of houses with residual insecticides can control Triatominae bugs. Infection in travelers is rare and can be avoided by not sleeping in such dwellings or by using bed nets if forced to do so.

Transfusion-induced Chagas' disease is a major health problem in endemic areas. A small number of cases have been reported in the US. Although screening for antibodies has been proposed,US blood banks currently rely on historical information to exclude potentially infected donors. Transfusion-induced Chagas' disease can also be prevented by adding gentian violet to blood in endemic areas if blood screening with serologic tests is not possible.

http://www.merck.com/mmpe/sec14/ch186/ch186d.html

[Gert van der Hoek]

Re: Chagas: experts warn of "silent killer"

'Kissing Bugs' found in Cocke County

To protect yourself from the Kissing Bug, experts recommend shaking your linens every night before you go to bed because the bugs like to hide out in dark, warm places.


June 22, 2007

By JEFF LENNOX


COCKE COUNTY (WATE) -- An insect known as the "Kissing Bug" is causing quite a stir in Cocke County. It's a blood sucking insect that can cause life-threatening reactions in rare cases.

The bug can be more dangerous than its name implies. Just ask Cocke County resident David Williams. "I am highly allergic and this is what caused me to be hospitalized."

In recent months, Williams says he has been bitten by the Kissing Bug twice. "The first bite that I got, I had a blood infection, and I had to go through anti-biotic treatment. I was sick for a few weeks."

Of the 130 known species, some can carry a deadly parasite called Chagas. The bugs live primarily in South America, but some varieties make their home in the southern portion of the United States.

The Centers for Disease Control tells 6 News it's tested Williams' bugs and found they don't carry the dangerous parasite.

That's a relief for this father of two, but he still wants people to be on guard. "I am trying to make people aware, so that nobody has to go through what I have had to go through."

To protect yourself from the Kissing Bug, experts recommend shaking your linens every night before you go to bed because the bugs like to hide out in dark, warm places.

Also, if you are going to be in the outdoors, try using a DEET-based mosquito repellent. These repellents work to fight off Kissing Bugs in the same way they do for mosquitoes.

In some rare cases in the U.S. the Kissing Bugs have been caught carrying the deadly disease called Chagas. The disease is usually slow to spread, but in the long run it can lead to heart failure.

Across the U.S., only six known cases have been reported where people died. That includes one fatal case in Tennessee.

The disease is widespread in Mexico, Central and South America where it kills close to 21,000 people a year.

http://www.wate.com/Global/story.asp?S=6699632&nav=0RYv