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VECTOR-BORNE DISEASES

Chagas Disease

WHAT IS CHAGAS DISEASE?

• Potentially life-threatening illness caused by the protozoan parasite Trypanosoma

cruzi

• Also known as American trypanosomiasis

• Known as the silent disease

• An estimated 8 million people have the disease

• Most do not know that they are infected

• Classified as a neglected tropical disease

WHY IS CHAGAS DISEASE A NEGLECTED TROPICAL DISEASE?

• WHO recognizes a group of diseases that have received insufficient attention

from governments and health agencies

• Are often diseases that affect people who live in low-income areas and regions

with hot, humid climates

• Are classified as Neglected Tropical Diseases

• Also called forgotten diseases

BURDEN OF NEGLECTED TROPICAL DISEASES

• In tropical and subtropical conditions in 149 countries

• Affect more than 1 billion people globally

• Cost developing countries billions of dollars annually

• Primarily affect persons living in poverty

• Without adequate sanitation

• Close contact with infectious vectors and domestic animals and livestock

CHAGAS DISEASE DISTRIBUTION

• Occurs principally in Latin America

• Increasingly being detected in North American, European, and Western Pacific

countries

• Due to population mobility between Latin America and the rest of the world

TRANSMISSION

• Transmitted by triatomine bugs (Kissing bugs)

• Live in walls or roof cracks of poorly constructed homes

• In rural or suburban areas

• Hide during the day and become active at night

• Feed on blood of mammals including humans

• Bite exposed area of skin, such as the face (Hence its name)

• Defecates or urinates close to the bite

• Parasite (trypanosoma cruzi) then enters the body

OTHER TRANSMISSION SOURCES

• T. cruzi can also be transmitted by:

• Consumption of food contaminated with T. cruzi

• Blood or blood product transfusion

• Passage from an infected mother to her newborn during pregnancy or childbirth

• Organ transplants

• Laboratory accidents

SYMPTOMS

• Symptoms are in 2 phases

• Acute phase (initial) – Lasts for 2 months

• In many cases a person displays no symptoms in acute phase

• Characteristic first visible signs - skin lesion or a purplish swelling of the lids of one eye

• Can also present fever, headache, enlarged lymph glands, pallor, muscle pain, difficulty in breathing, swelling, and abdominal or chest pain

SYMPTOMS

• Chronic phase

• Parasites hidden mainly in the heart and digestive muscles

• Up to 30% of patients suffer from cardiac disorders and up to 10% suffer from digestive, neurological or mixed alterations

• In later years, can lead to sudden death due to cardiac arrhythmias or progressive heart failure

• Medical care cost of patients with chronic symptoms calculated to be >80% higher than the cost of spraying residual insecticide to control vectors and prevent infection

CHAGAS DISEASE BURDEN

PREVENTION AND CONTROL

• No vaccine

• Vector control – Most effective prevention method

• Blood screening used to prevent infection from blood transfusion or organ transplantation

• Vector cannot be eradicated

• Eliminate transmission and early health care access

• Treatment with antiparasitic drugs

• Can be 100% effective in curing the disease if given early after initial infection

• Efficacy diminished the longer a person has been infected

• Problem considering many persons experience no acute symptoms and don’t know they are infected

PREVENTION AND CONTROL

• T. cruzi can infect several species of the triatomine bugs, the vast majority of which are found in the Americas.

• Recommended approaches to prevention and control:

• Spraying of houses and surrounding areas with residual insecticides

• House improvements and house cleanliness

• Personal preventive measures such as bednets

• Good hygiene practices in food preparation, transportation, storage and consumption

• Blood donor screening

• Testing of organ, tissue or cell donors and receivers

• Access to diagnosis and treatment of people with medical indication or recommendation to receive antiparasitic treatment, especially children and women of child-bearing age before pregnancy

• Screen newborns and other children of infected mothers without previous antiparasitic treatment

GLOBAL RESPONSE

• Since 1990’s many successes in parasite and vector control

• Led to substantial reduction in transmission and increased access to diagnosis

and treatment

• Risk of transmission via blood transfusion reduce by universal blood screening

in all blood banks of Latin American countries with the disease

CHAGAS DISEASE CHALLENGES

• Emergence of Chagas disease in regions previously considered to be free of

the disease

• Persistence in regions where control had been in progress

• Spread of the disease mainly due to increasing population mobility between

Latin America and the rest of the world

• Enhanced access to diagnosis and treatment for millions of infected people

WHO RESPONSE TO CHALLENGES

• Increase networking at the global level and reinforce regional and national

capacities, focusing on:

• Strengthening Chagas disease surveillance

• Preventing transmission by blood transfusion and organ transplantation

• Increase screening and diagnosis of infections

• Expanding primary prevention of congenital transmission and case management of

congenital and non-congenital infections

• Promoting consensus on adequate updated case management

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