Railroad Stop at Lassance

At about the same time, Europeans and Brazilians intruded into the forests of Brazil to build a railroad connecting Rio de Janeiro with the northern city of Belem, near the mouth of the Amazon River. Indians, animals, insects, and parasites resisted the invaders, causing a standstill in Lassance, located on the banks of the Sâo Francisco River in Minas Gerais. Rail workers from Asia and Europe and slaves from Africa died by the thousands. In 1908, Estrada de Ferro Central do Brasil (the Central Railroad of Brazil) invited Carlos Chagas to come to Lassance.

Thirty‑one years old, Carlos left his wife in Juiz de Fora, her native village, in December 1908. He traveled by train for twenty‑four hours to Lassance, the end of the rail. Named after a French railroad engineer, Lassance had 1,500 people. African, Chinese, Irish, and Portuguese railroad workers lived in mobile encampments of boxcars fitted with bunks. Chagas was given one boxcar to serve as clinic, dormitory, and laboratory.

Lassance also had comfortable ranch homes and townhouses for the long‑established Portuguese settlersmerchants, farmers, and rancherswho considered themselves a class apart. Socially positioned between the upper‑class denizens and lower‑class migrants were itinerant cowboys. The cowboys fought with each other and looked down upon the immigrants. The immigrants in particular suffered from the parasitic diseases of the tropics. They had not developed partial immunity, and many died from acute infections of parasitic diseases. (Partial immunity occurs when someone is already infected with parasites and usually will not suffer another acute attack because the parasites partially protect the host; this is the case with Chagas’ disease.)

Chagas had to treat the ailments of the people of Lassance. Parallel to the tracks lay the main street, Avenue Alfonso Pena, where the merchants, landowners, and authorities lived in townhouses, enclaves shut off from the bustle and dust of the street. Farther down were the infamously named streets, including Street of the Knife and Street of the Shot, all noted for their brothels, bars, and fights. Along these streets, merchants catered to the Brazilian cowboys, mixed breeds of blacks, Indians, and Portuguese, who herded cattle through Lassance while on the way to slaughterhouses in the southern cities of Curvelo and Belo Horizonte.

Carlos Chagas described Lassance years later to his son Carlos Chagas Filho (1988):

The village resembled the many movie versions of the settlement of the American West. The boisterous visitors considered me an “officer.” For several months none of those wounded during brawling (I could hear the shots in the distance) would come to the hospital I directed. After awhile, they came to me, and I treated their injuries.

Chagas treated the railroad workers so they could lay tracks. He treated them with arsenic for syphilis and quinine for malaria; he also advocated burning chrysanthemum to keep down the mosquitos. He employed a railroad car as a hospital and conducted research using another railway car as laboratory, clinic, and bedroom.

As Chagas treated the injured and diseased, he noticed that some symptoms were not from malaria. Like clockwork, the malarial parasite sporulates periodically with accompanying parasitemia (alternating chills and fevers). Latin Americans still refer to malaria as either M. quotidian (P. vivax causes paroxysms every twenty‑four hours), M. tertian (P. falciparium causes paroxysms every forty‑eight hours), and M. quartan (P. malariae causes paroxysms every four days). Chronic malaria also results in splenomegaly (enlargement of the spleen). Unlike malaria with its violent attacks, some Lassance patients suffered arrhythmias and other cardiac disorders which resulted in a sudden and nonviolent death.

At first, Chagas figured it was morbus gallicus (French disease), as syphilis was popularly called in Brazil, and treated the patients with arsenic. He wrote (Chagas Filho 1993:81):

Faced with an unknown disease, one usually thinks of syphilis, especially for railroad workers, undernourished, ravaged by malaria, victims of morbusgallicus, which usually accompanies those laying iron tracks. A population complaining about irregular heartbeats and atypical arrhythmias, indications of cardiac insufficiencies, and frequently leading to sudden death… inexplicable! Barbeiros /Vinchucas : Triatoma infestans

A clue was provided by an engineer who showed Carlos an arthropod insect known as a barbeiro or vinchuca (Triatoma infestans ) that infested the barracks and sucked blood from the workers during the night. The workers complained that barbeiros bit them nocturnally, drew blood, and caused painful welts. The engineer inquired whether barbeiros as well as anopheles mosquitos spread malaria, and Chagas knew that anopheles mosquitos transmitted plasmodium parasites whose sexual reproductive cycle was limited to the gut of the mosquito. “Knowing the domiciliary habits of the insect, and its abundance in all the human habitations of the region,” Chagas (1922) wrote, “we immediately stayed on, interested in finding out the exact biology of the barbeiro, and the transmission of some parasite to man or to another vertebrate.”

^{Figure 3.}

^{Triatoma infestans.}

Barbeiros have six strong legs, an inch‑long body covered with fragile, transparent wings, bulbous eyes, and a proboscis nested under its body that can extend downward to ingest blood from mammals, including humans. Brazilians call these triatomine insects barbeiros, from the Portuguese word for barber, indicating that these insects cut like a barberreferring not to the fact that barbers accidentally cut the face with razors but that they also practice bloodletting, done at the time for medical purposes. Barbeiros are scientifically classified as Triatoma infestans (see Figure 3).

Carlos Chagas observed that barbeiros are sensitive to light and during the day hide in cracks and crevices of walls and ceilings where they rest, copulate, and lay eggs, which are tiny, white, and ball‑shaped. Barbeiros are considered vampire bugs; they become active at night, descend from nests, are drawn to warmth, and draw blood from animals and humans. Faces are attractive targets that barbeiros pierce with their needle‑sharp proboscises. They inject anesthetic and anticoagulant fluids that enable them to leisurely ingest blood from unwary and tired victims. Sleepers sometimes awake and smash the barbeiros, exploding the blood on their bodies or other surfaces as the bugs sluggishly return to their nests. They are superb crawlers and can attack victims by crawling beneath mosquito netting or from inside mattresses.

People also refer to barbeiros (or vinchucas ) as “kissing bugs” because of their predilection for the face. Chagas called the resulting chagoma (carbuncle sore) from a bite beneath the eye Signo de Romaña and pointed this out as an important diagnostic indicator of acute Chagas’, discussed more in Chapter 4 (see Figure 4).

^{Figure 4.}

^{Child with Romaña’s sign, a chagoma that occurs at the site of the bite from the vinchuca bug. This occurs during the acute phase in about one‑fourth of those infected with T. cruzi. (Photograph from the Pan American Health Organization)}

Barbeiros (vinchucas) are triatomines, with more than 100 species that are vectors of Trypanosoma cruzi. Triatoma infestans is the most widespread and effective species vector of T. cruzi in Bolivia, and Bolivians refer to it as vinchuca. Sometimes classified as reduviid bugs, barbeiros do not have the painful bite of other reduviids. Barbeiros have injector‑needlelike snouts or noses that fold back under their bodies and protrude down, like half‑opened jackknives, to pierce the victim’s skin. They can engorge more blood than their body weight, and when they defecate they can leave small blotches of tobacco‑like stains on the skin. They need blood meals, one for each of five instar (life) stages, in which they transform from barely the size of a flea to that of a small cockroach. At the final, adult stage, they grow wings, copulate, lay eggs, and die. Rather simple in their needs, triatomine insects need only a place to hide during the day and mammals to feed on during the night. (See Chapter 4 and appendices for more on triatomines).

Lassance was infested with barbeiros because of its impoverished socioeconomic conditions and human intrusion into nearby forests. Triatomines were driven from their native habitats as railroads expanded. Crawling aboard railway cars, barbeiros followed westward expansion across Brazil. Many houses for humans were made of thatched roofs and adobe walls, with cracks, crevices, and cornices providing nesting sites for barbeiros. Carlos Chagas recognized the impact poverty has upon the spread of insects, parasites, and disease, something Walter Reed also had observed in regard to malaria.

Years earlier, Charles Darwin had also been fascinated by vinchucas, and it could be wondered if Darwin’s fascination augmented Chagas’ curiosity about these bugs. Both shared essential ingredients of successful fieldworkers, curiosity about certain creatures and how they relate to other creatures. It is likely that Carlos Chagas, like most classically trained biologists at the time, had read about vinchuca bugs in the Diary of the Beagle, written by Darwin on March 26, 1835:

We crossed the river of Luxan (Andean region of Mendoza)… At night I experienced an attack, & it deserves no less a name, of the Benchuca, the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over ones body; before sucking they are quite thin, but afterwards round & bloated with blood, & in this state they are easily squashed. They are found in the Northern part of Chili & in Peru: one which I caught at Iquiqui was very empty; being placed on the table & though surrounded by people, if a finger was presented, its sucker was withdrawn, & the bold insect began to draw blood. It was curious to watch the change in size of the insects body in less than ten minutes. There was no pain felt.This one meal kept the insect fat for four months; In a fortnight, however, it was ready, if allowed, to suck more blood. (Darwin, in Keynes 1988:315)

Several years later, Darwin wrote in his zoology notebook at Edinburgh (1837‑1839) a partial description of vinchucas in French, which I translate: “Vinchucas or Benchucas. The individual wings can be (four) five lines [lignes ] long and they fly.” Darwin had found this quote from an earlier description by the naturalist Azara (1809, I:208‑9): “La vinchuca [is] very annoying for those who travel from Mendoza to Buenos Aires… It is a beetle or scarab, whose body is oval and very flat, and who becomes fat like a grain of raisin, from the blood which he sucks. This insect only comes out at night. The individual wings can be five lines [lignes] and they fly, at least the large ones.”[5]He was referring to the fact that vinchucas grow wings only at the adult, or fifth instar, stage.