Chikungunya arrived in Brazil before it was pointed out, reveals research

Publicação: 11 de March de 2019

The author, Dr. Thiago Moreno L. Souza, alerts to the possibility of new arboviruses and the importance of paying close attention to the Mayaro and Oropouche viruses

Researchers analyzed blood samples and the results showed that the chikungunya virus was already circulating in Brazil in 2013, but went unnoticed by the health authorities

An article recently published in Scientific Reports, from the Nature Group, indicates that the chikungunya virus arrived in Brazil at least a year earlier than when it was detected by public health surveillance systems. The result of the work entitled “Emergence of the East-Central-South-African genotype of Chikungunya virus in Brazil and the city of Rio de Janeiro may have occurred years before surveillance detection“, shows that many patients were misdiagnosed because of the failure to correctly identify the virus. The research aimed to alert health authorities to the problem. This study had the presence of researchers from the Mailman School of public health, Columbia University, and the Oswaldo Cruz Foundation (Fiocruz).

Dr. Thiago Moreno L. Souza, the research’s author and Biochemistry professor at Fiocruz in Rio de Janeiro, points out that the finding is important to confirm and quantify the delay of surveillance systems in detecting the entry of a new agent. “If the date of entry was within our margin of error we could say that the surveillance system was efficient. But since this was not the case, we quantified this delay, this inefficiency, in approximately a year between the date of entry and detection”, he explains. According to him, from this parameter it is possible to reinforce the surveillance systems and to evaluate if the measures are effectively taking effect through the quantification of the values.

In this study, the scientists analyzed blood samples collected at the National Institute of Infectology Evandro Chagas (INI / Fiocruz) between March 2016 and June 2017, using a genetic test to track the virus’ entry into Brazil, both temporal and geographical. From the analyzed samples, over 60% tested positive for the virus. Within these cases, 40 chikungunya-positive samples that had negative results for dengue and zika were evaluated again using the CII-ArboViroPlex method, developed by the University of Columbia’s Infection and Immunization Center (CII), which simultaneously achieves results for presence of zika, all serotypes of the dengue virus, Nile fever and chikungunya. The test confirmed the previous assessment, but with greater sensitivity, suggesting the possibility of being able to identify the virus that other tests could not.

Of these samples, 14 represented specific dates from the 15-month period before and were subsequently analyzed using another method of detection, surveillance and discovery of arboviruses developed by the IIC. The test allowed almost complete recovery of DNA sequencing and identification of chikungunya virus genotypes. The analysis of these sequencings showed a strong correlation between the genetic divergence and the date the sample was collected, that is, a one-year window of time was found. The result allowed the researchers to identify a “molecular clock” based on the rate of mutations between the samples. This timeline suggests that the virus could have circulated in 2012 and was probably imported from Central Africa after a 20-year neglected circulation in other parts of the world.

To Dr. Moreno, the chikungunya virus circulated during this time without being perceived for logic reasons behind the diagnostic of the diseases. “Operating in the context of the twentieth century, you presuppose certain disease and research on it. Since in 2013 the concern was dengue, we tested for it and, if it was negative, there was a differential diagnosis algorithm to know what disease the person presented at that moment”, he says. The researcher adds that within the coherence that operates in the 21st century with the emergence of new diseases, is that negative cases need to be tested to evaluate a new agent with potential public health risk is yet to come.

In this sense, the researcher alerts to the possibility of the emergence of new arboviruses. “The Brazilian scenario points to this, we are hyperendemic for dengue, we have reemergence of yellow fever, we are one of the only countries with two circulating chikungunya genotypes, we had a massive circulation of Zika, so, all this shows that Brazil is particularly vulnerable to emergence of new arboviruses”, he acknowledges while emphasizing the importance of paying attention to the Mayaro virus, which is from the chikungunya family and is more restricted to the Midwest and North regions, and to the Oropouche virus, arboviruses with a certain level of circulation in the North of the country and has a higher morbimortality rate.

Genotypes in Brazil

Another important evidence from the study demonstrates the entry of the chikungunya virus in Rio de Janeiro in a single event, coming directly from Sergipe. The research also reveals that large Brazilian cities such as Rio de Janeiro have had autochthonous circulation of the virus since March 2016, when it co-circulated with dengue and zika viruses. Asked about the possibility of other viruses that cause arboviruses, like the zika, also went unnoticed by the health authorities, the researcher is emphatic to state that it in fact happened. “In mid-2018 we published a study revealing that zika circulated in Brazil for at least one year before being perceived, when the epicenter of circulation was the Northeast region, and then spread to other states and to other countries of South America, America Central and from there to Florida”, he explains.

Currently two genotypes of the Chikungunya virus circulating in Brazil, one from Asia and the other from Central Africa. The Asian genotype was confirmed in the Northern region (Oiapoque, Amapá state) and the ECSA genotype was first identified in the Northeast region (Feira de Santana, Bahia). The ECSA genotype was later detected in other states, especially Sergipe and Rio de Janeiro. The phylogeographic reconstruction of the research suggests that the Central African region is the likely source of the ECSA lineage that has spread throughout Brazil. However, sufficient data on Central African ECSA genomes are not available for a definitive conclusion. Thus, a stronger sampling of chikungunya strains in that region could increase the molecular epidemiological understanding of the neglected ECSA genotype circulation since the 1980s, which would help pinpoint the country of origin of the Brazilian ECSA outbreak more precisely.

The research analyzed sequences from the states of Alagoas, Bahia, Sergipe, Paraíba, Pernambuco and Rio de Janeiro between 2012 and 2014. The results confirm that the introduction of the ECSA genotype in Brazil probably occurred in Bahia. However, the analysis diverges in the average time of introduction of this genotype up to one year prior to the previous estimates. From Bahia, the genotype spread to Alagoas and Paraíba, as well as to Rio de Janeiro. The temporal reconstruction indicates that the introduction of the genotype in Rio de Janeiro occurred most likely at the beginning of 2014 and that from Rio de Janeiro this line returned to the Northeast region spreading to Sergipe.

Measures to prevent chikungunya virus circulation

Dr.  The researcher observes that there are more and more disordered occupations, more orderly occupation in areas of preservation, replacement of forest areas by urban areas, where the mosquito already inhabited. In addition, he stresses the lack of proper waste management. “Many dumps are close to large urban centers and after the rains there is no control of standing water tanks”, he laments. Besides this, the professor draws attention to the need for basic sanitation measures, a global challenge to contain arboviruses.

Finally, to control the entry of possible new viruses in Brazil, Dr. Moreno acknowledges that the challenge is to prevent the entry of new agents before they cause an epidemic in public health, so that the first cases can be identified, and the people left in contact isolation, a quarantine, for a set time, in order to prevent them from spreading this new agent. “This measure, for example, is similar to that used against Ebola in Africa, with continuous surveillance”, he concludes.

The disease

Chikungunya fever is a global public health problem with profound impact on tropical and subtropical regions of the world, where Aedes aegypti and Aedes albopictus mosquitoes are prevalent. The most common initial symptoms are fever and intense joint pain, especially in the back, which is the main difference from dengue. Usually the symptoms appear 7 days after the person is bitten by the mosquito and lasts up to 14 days. The swelling of the joints can appear up to 60 days after the beginning of the first signs and symptoms.

According to information released by the Ministry of Health, Brazil had a reduction of 51% in chikungunya cases this year compared to the same period in 2018. As of February 02, a total of 4,149 probable cases of infection were recorded, against 8,508 cases reported last year. The incidence in 2019, is two cases per 100 thousand inhabitants. The North region had the highest number of cases, a total of 2.730, followed by the Midwest, with 789 cases; and Northeast, with 446 cases. For more information, click here .