In the world of insects, rare are those whose common name evokes romantic associations, but this is precisely the case with the so-called "kissing bug". However, behind this innocuous name lies a serious threat to human health. It is an insect that is a vector, or carrier, of a dangerous parasitic disease that can leave permanent and life-threatening consequences. This bug does not belong to the species of common bed bugs (Cimex lectularius), which are primarily pests, but is a group of insects from the subfamily Triatominae, known for their hematophagous diet, meaning they feed on blood.

Anatomy and habits of the silent nocturnal predator

Triatomine bugs are insects characterized by a specific life cycle and behavior that makes them extremely effective disease vectors. Adult individuals can grow up to several centimeters, and their bodies are flattened, which allows them to hide in narrow cracks in walls, floors, furniture, under pictures, and even in thatched roofs or animal nests. Their activity is primarily nocturnal. During the day, they rest in their hiding places, and with the onset of darkness, they emerge in search of food – the blood of warm-blooded vertebrates, including humans, domestic animals, and rodents.

What makes this bug particularly interesting is its nickname. The name "kissing bug" comes from its tendency to choose soft tissues on the face for its bite, especially around the lips and eyes, attracted by the warmth and exhaled carbon dioxide of a sleeping person. The bite itself is almost painless. The bug uses its sophisticated mouthpart, the proboscis, which consists of two tubes. Through one, it injects saliva containing anesthetic substances, so the victim does not feel the bite, and anticoagulants that prevent blood clotting. Through the other tube, it sucks blood, and feeding can last from ten to fifteen minutes. After its meal, the bug retreats back to its hiding place.

The parasite Trypanosoma cruzi and the mechanism of transmission

The danger of the triatomine bug lies not in the bite itself, but in what happens immediately after it. A bug infected with the parasite Trypanosoma cruzi often defecates on the victim's skin during or immediately after feeding. Its feces contain infectious forms of the parasite. When a person, usually in their sleep, scratches the itchy bite site, they unconsciously rub the feces into the bite wound or into the mucous membrane of the eye or mouth. In this way, the parasite enters the bloodstream and begins its destructive journey through the body.

Besides this primary, vector-borne mode of transmission, Chagas disease, as the illness caused by this parasite is called, can be transmitted in other ways. These include transfusion of infected blood, organ transplantation from an infected donor, vertical transmission from mother to child during pregnancy or childbirth, and, more rarely, consumption of food or drink contaminated with the feces of infected bugs.

Chagas disease: A silent threat in two phases

Chagas disease is an insidious illness that develops in two clearly defined phases: acute and chronic. Each has its own specificities and clinical picture.

Acute phase: The onset of infection

The acute phase occurs immediately after infection and can last from a few weeks to two months. During this period, parasites circulate in the blood in large numbers. Paradoxically, the symptoms are often mild, non-specific, or completely absent, which is why the disease in this crucial phase often goes unrecognized. If symptoms do appear, they may include fever, general weakness, muscle and body aches, headache, loss of appetite, and a rash. A localized swelling, known as a "chagoma," may appear at the site of parasite entry. If the parasite enters through the conjunctiva of the eye, a characteristic unilateral swelling of the eyelid, known as the "Romaña's sign," may occur. Although this phase can be dangerous for young children and immunocompromised individuals, in most infected people, the symptoms resolve spontaneously.

Chronic phase: Years of smoldering disease

After the symptoms of the acute phase subside, the disease enters a long, latent, or indeterminate chronic phase. During this period, which can last for years, or even decades, the infected person has no symptoms. The parasites have withdrawn from the bloodstream and settled in the tissues, primarily in the muscle cells of the heart and the smooth muscles of the digestive system. Despite the apparent calm, the parasite slowly but surely causes inflammatory processes and tissue damage.

In about 30 to 40 percent of those infected, after a long asymptomatic period, the disease progresses to the symptomatic chronic phase, manifesting with serious and irreversible complications affecting the heart and digestive system.

Devastating consequences on the heart and digestive system

The long-term presence of the parasite Trypanosoma cruzi and the chronic inflammatory reaction it causes lead to the destruction of the nerve ganglia that control the function of internal organs. The consequences are most severe on the cardiovascular and digestive systems.

Cardiac complications: Chronic Chagas cardiomyopathy is the most serious consequence of the disease. The heart muscle weakens and the heart progressively enlarges (dilated cardiomyopathy), losing its ability to pump blood effectively. This leads to heart failure, with symptoms such as shortness of breath, fatigue, leg swelling, and fluid retention. Damage to the heart's electrical system causes various types of arrhythmias (irregular heartbeat) and conduction disorders, which can lead to fainting, the formation of blood clots (thromboembolism), and sudden cardiac death.

Digestive complications: Similarly, the destruction of nerves in the wall of the digestive tract leads to impaired peristalsis. The most common manifestations are megaesophagus (pathological enlargement of the esophagus) and megacolon (pathological enlargement of the large intestine). Megaesophagus causes dysphagia, or difficulty swallowing, regurgitation of food, chest pain, and weight loss. Megacolon manifests as severe chronic constipation that can last for weeks, abdominal pain, and, in the most severe cases, can lead to intestinal obstruction (volvulus).

Diagnosis and treatment: A race against time

The diagnostic approach depends on the phase of the disease. In the acute phase, diagnosis is made by directly detecting the parasite in the blood using a microscopic examination of a blood smear. However, since this phase is often asymptomatic, it is rarely diagnosed. In the chronic phase, when parasites are no longer present in significant numbers in the circulation, diagnosis is based on serological tests, such as the ELISA test, which detect specific antibodies to Trypanosoma cruzi in the blood. After confirming the infection, further tests such as an ECG and an echocardiogram are necessary to assess the condition of the heart.

Treatment of Chagas disease is a challenge and is most effective if started as early as possible. There are two main antiparasitic drugs used: benznidazole and nifurtimox. These drugs are very effective at killing the parasite during the acute phase, almost always leading to a cure. However, their effectiveness significantly decreases in the chronic phase of the disease. Although treatment in the chronic phase cannot repair existing organ damage, it can slow or prevent further progression of the disease. The therapy is long-term and can be accompanied by significant side effects, including skin reactions, digestive problems, and neurological issues, requiring careful medical supervision. In the later stages of the disease, treatment is mainly symptomatic and focused on complications, which may include heart medications, pacemaker implantation, or surgical procedures on the esophagus and large intestine.

Prevention and global distribution

Prevention is key in the fight against Chagas disease. In endemic areas of Latin America, primary measures include vector control by spraying insecticides, improving housing conditions (plastering walls to eliminate cracks), using insecticide-treated bed nets, and educating the population. It is also extremely important to rigorously screen blood and organs for donation to prevent iatrogenic transmission.

Although historically linked to poor rural areas of Latin America, Chagas disease is now a global health problem. Due to population migration, infected people live all over the world, including North America and Europe. Therefore, raising awareness among healthcare professionals in non-endemic countries is crucial for the timely recognition and treatment of this "silent" disease. Comprehensive information on Chagas disease is available on platforms of the World Health Organization, which continuously monitors the global epidemiological situation.