Death by urban yellow fever could trigger the Countrys health network red alert

Despite seeming unusual, investigations will signal whether the diseases combat protocols should be changed


IEC received the material of a clinical suspicion of hemorrhagic dengue, but the result was negative Other exams confirmed yellow fever

The last case of urban yellow fever transmission in Brazil took place in 1942, in Acre State. For this reason, the death in Natal (RN) called special attention from the sanitary authorities. If the victim acquired the infection naturally, the Brazilian health network could trigger an alert. This is the opinion of Dr. Pedro Vasconcelos, virologist and former director of the Evandro Chagas Insitute (IEC), in Pará State.

IEC elaborated the report confirming the recent death by urban yellow fever. Interviewed by the Brazilian Society of Tropical Medicine, Dr. Vasconcelos explains how the case has been conducted. He believes the investigations will point whether the disease combat protocols should be changed, although, initially, this is an unusual case.

Find the full interview below:

BSMT: How was the cases investigation?

Dr. Pedro Vasconcelos: First of all it is important to clarify that IEC received the material as a suspicion case of hemorrhagic dengue fever. After tests for dengue turned negative, it is our routine to test for other diseases with similar clinical signs (differential diagnosis in syndromic surveillance) trying to clarify the ethiological diagnosis. This way, other tests for hemorrhagic fevers including yellow fever, returned a positive result in immunohistochemistry   (IHQ) The result was surprising, I would even say unexpected. This way, new IHQ tests were conducted using specific serum for yellow fevers both policlonal and monoclonal forms, and the results confirmed yellow fever. In face of this finding, all investigations on the patients prior trips and vaccines were conducted by the Health Ministrys Health Surveillance Secretary and, apparently was unsuccessful explaining a possible trip to an endemic area or not being vaccinated against the disease. An eco-epidemiological investigation was also initiated aiming to capture possible the yellow fever virus potential mosquito vectors. These studies are under development.

BSMT: Does this result mean an alert for the Brazilian health network?

Dr. Pedro Vasconcelos: If the case is confirmed as a naturally acquired infection, then yes. This would mean the the reintroduction of yellow fever in an area where the last reported cases took place 80 years ago. We must exclude the possibility of the acute viscerotropic disease by the 17DD vaccine, whichs initial cases in Brazil took place in 1999 and were published in The Lancet in 2001, one of the worlds most renowned scientific journals and I had the honor and privilege to conduct the articles publication. Obviously, if this is a naturally acquired yellow fever case, we must extend urban (Aedes aegypti) and wild (Haemagogus and Sabethes) vector surveillance, as well as the primary hosts seeking epizootic diseases in non-human primates and, depending on the results, part of the population may have to undergo vaccination.

BSMT: Are there suspicions of other deaths by the disease?

Dr. Pedro Vasconcelos: As far as I know, there are not. Apparently this was an isolated case, which is very unusual.

BSMT: Are the disease combat protocols going to be changed or the case can be dealt with as unusual?

Dr. Pedro Vasconcelos: Everything depends on the investigations by the Health Surveillance Secretary (SVS), Rio Grande do Norte Health Secretary and IEC. At first this could be considered an unusual case, but we must wait for the investigations results. We know caution cant harm anyone.

BSMT: How is the death by yellow fever being treated by the scientific community?

Dr. Pedro Vasconcelos: With caution, but calmly, since the surveillance is active and sensible, besides ready for early diagnosis of other cases that eventually happen. I remember in 2008, in Paraguay, an urban yellow fever outbreak took place in Asuncións suburbs, and the vector control actions combined to the vaccination of the exposed population eliminated the transmission, which became restricted to a 9-case cluster. This way, the actions are known and can be immediately put in practice if new cases in humans, or a epizootic (monkey death by the yellow fever virus) or even the detection of the virus in potential mosquito vectors are found. The Health Ministry along with the State Health Secretary are paying close attention and ready to intervene if necessary.…