The health conditions of Rio de Janeiro denizens during Brazil’s colonial and imperial periods are currently being deciphered at the Oswaldo Cruz Foundation (Fiocruz). And two of the research team’s recent discoveries stand out from the rest. The first is the widespread dissemination of intestinal worms: they afflicted the poor, known to live in less-than-salubrious settings, as well as the rich, who supposedly enjoyed the protection of better sanitation. The second discovery is a possible new origin for tuberculosis in African slaves. In the May 2013 issue of Emerging Infectious Diseases, the authors indicate that at least some Africans already had the infection when they arrived in Brazil, as opposed to becoming contaminated after disembarking in Rio, then the country’s capital.
The group coordinated by biologist Alena Mayo Iñiguez at Fiocruz was able to arrive at these conclusions after completing genetic and parasitological tests on human skeletons found in recent years at three archaeological sites in Rio: the cemeteries of Pretos Novos, Praça XV de Novembro, and Nossa Senhora do Carmo Church. Now confined in a relatively small downtown area – Praça XV and Carmo Church are just a few blocks apart in the very center of Rio, and Pretos Novos is located in the port district, about two kilometers northwest of there – these ancient graveyards received the mortal remains of people from very different social backgrounds. That is why the information extracted from these remains provides a clearer view of how residents lived and died in what was once Brazil’s largest and most important commercial hub, in the country’s colonial and imperial days.
In the 18th and 19th centuries, the Praça XV de Novembro Cemetery received the dead from every social class, especially those who fell victim to epidemics. It is therefore able to paint a general picture of public health in Rio at the time. “In these skeletons, we identified Amerindian, European, and African genetic markers,” says Iñiguez, researcher at Fiocruz’s Laboratory of Molecular Biology of Trypanosomatids and coordinator of the studies.
Analysis of the material collected from the remains of 10 people revealed that 80% of them were infected by intestinal parasites – especially worms and protozoans. The most common parasites were worms of the genus Trichuris. With an elongated body that measures up to 4 centimeters in length, these worms live in the intestines and can cause bleeding and anemia when present in large numbers. In addition to Trichuris, tapeworm and roundworm eggs were also found. Iñiguez’s group found Trichuris eggs in 70% of the analyzed samples. According to the researchers, this is actually a conservative infection rate, because the material had been washed before being analyzed. In the Praça XV and Pretos Novos cemeteries, the Fiocruz research team worked on materials collected during archaeological salvage operations, some of them unearthed during the construction work now underway to revitalize the city’s port district. At Nossa Senhora do Carmo Church, the former See of Rio de Janeiro, the samples were analyzed in loco where they were found when the building underwent renovations in 2007. “When we collected the materials, our focus was genetic research,” says Iñiguez. The bones were reinterred after analysis.
At Nossa Senhora do Carmo Church, where wealthy, usually European-born families were buried in the 17th to 19th centuries, the infection rate was only 12%. Though lower, the researchers were surprised at this figure. “The variety of parasites we found there is the same as in Praça XV,” says Iñiguez. “This shows that everyone, rich and poor alike, was exposed to the same environment and the same risks.”
A european disease
But in the case of tuberculosis, the researchers observed a very different scenario than they did for intestinal parasites. The pulmonary disease, caused by the bacterium Mycobacterium tuberculosis, was much more prevalent among the wealthy than among the poor. Together with the rest of the research team, pharmacist Lauren Jaeger, a PhD student advised by Iñiguez, identified the tuberculosis bacterium’s genetic material in 17 out of 32 bodies (nearly all of them of European descent) discovered at Nossa Senhora do Carmo Church and identified by the team led by archaeologist Ondemar Dias from the Brazilian Archaeology Institute (IAB). The rate of infection by tuberculosis among the Africans buried in Pretos Novos Cemetery was 25%, according to a study conducted in partnership with paleopathologist Sheila de Souza from Fiocruz’s Sergio Arouca National School of Public Health.
The researchers believed that the higher frequency of tuberculosis among people of European descent is consistent with history, as the disease was highly prevalent in Europe at that time. “Europeans played an important role in disseminating this disease across the New World,” says Iñiguez.
Although the European influence on the spread of tuberculosis cannot be denied, analyses conducted on the mortal remains of slaves buried at Pretos Novos Cemetery are leading researchers to rethink a long-held belief: that Africa was a tuberculosis-free continent and that slaves brought to Brazil were not infected until they got here.
1 and 2 Leo Ramos 3,4 and 5 Jaeger. LH. Et Al Acta Tropica (2013)Death upon arrival
Rediscovered in 1996 during renovations to a house in the Gamboa neighborhood of Rio, when construction workers drilled boreholes to build the foundation and found thousands of teeth and human bone fragments, the Pretos Novos Cemetery received slaves who died between 1769 and 1830 either during the long journey across the Atlantic or soon after arriving in Brazil. At Pretos Novos, the bodies were thrown into shallow mass graves. They were often macerated with wooden sticks, making it difficult to identify the skeletons – an analysis of the material by the team headed by bioanthropologist Ricardo Ventura Santos suggests that most of the bones at Pretos Novos had belonged to men who died between the ages of 18 and 25 (see Pesquisa FAPESP Issue No. 190).
“Since these slaves never even left the port, they must have already been infected when they got here,” says Souza, co-author of the study published in Emerging Infectious Diseases. “The fact that they carried the bacteria certainly increased their risk of getting sick later on, under the harsh living conditions that they endured as slaves.” At present, however, it is impossible to know whether they were infected upon coming into contact with Europeans in Africa or even before, by older strains of the bacterium that were already circulating in the continent.
Iñiguez and her group hope to answer that question in the coming years. For this, they will need to perform molecular tests that can analyze the DNA of bacteria found in the human remains at Pretos Novos Cemetery and compare it to modern strains of the disease. “We are adapting some molecular biology techniques in order to work with the ancient material,” says Iñiguez. “Besides enabling us to identify the parasites that afflicted those populations, studying the DNA sequences will allow us to analyze the evolution [of these pathogens] and compare them to the bacteria seen today.”
JAEGER, L.H. et al. Mycobacterium tuberculosis complex in remains of 18th–19th century slaves, Brazil. Emerging Infectious Diseases. v. 19, n.5. May 5, 2013.
JAEGER, L.H. et al. Paleoparasitological analysis of human remains from a European cemetery of the 17th–19th century in Rio de Janeiro, Brazil. International Journal of Paleopathology. May 20, 2013.
JAEGER, L.H. et al. Paleoparasitological results from XVIII century human remains from Rio de Janeiro, Brazil. Acta Tropica. Nov. 27, 2012.
JAEGER, L.H. et al. Mycobacterium tuberculosis complex detection in human remains: tuberculosis spread since the 17th century in Rio de Janeiro, Brazil. Infection, Genetics and Evolution. Aug. 27, 2011.