Mosquitos still a risk to Brazil public health

By: Emily Green
Impunity Watch Reporter, South America

RIO DE JANEIRO, Brazil — Although the number of Zika cases have dropped significantly, Brazil’s public health is still threatened as summer approaches. Outbreaks of Zika, Dengue fever, and Chikungunya fever are all possible in the coming warmer climate.

The larvae of the mosquito Aedes aegypti. Image Courtesy of Eduardo Knapp.

All three of these diseases are carried by the same bug, the Aedes aegypti mosquito, which is endemic to Brazil. The Zika outbreak received the most attention in 2015. The world watched as mosquitos plagued the country and created tragic stories of malformations in babies of infected women. Although Dengue and Chikungunya fevers were not in the spotlight, they were spread by the same mosquito and caused a record 800 deaths in Brazil that same year. Most of these deaths occurred in the impoverished northeast region where urbanization grows rapidly. In total, these mosquitos infected approximately 4 million people in the country.

However, statistics show that Brazil has seen some improvement since then. Only 16,800 new cases of Zika were reported from January to November in 2017. This is compared to the 214,100 cases during those months in 2016. Similarly, the number of cases of Dengue fever and Chikungunya fever also fell by 83.7% this year.

Despite these positive trends, at least 357 Brazilian cities are still at risk of a renewed outbreak. These cities are considered at risk because larvae from infectious mosquitos were found in more than 4% of properties visited. In comparison, 2,450 cities were found to be a satisfactory situation where mosquito larvae were found in less than 1% of property. The Northeastern area has the highest number of cities at risk. Scientists expect outbreaks in the upcoming summer because conditions are conducive for mosquitos to thrive. They warn that the most common type of breeding site for these mosquitos are storage areas of water in drums, barrels, and vats.

Of the diseases, Dengue fever is the most dangerous and can be lethal in its hemorrhagic form. Chikungunya can lead to chronic joint problems as well. As the mildest of the three diseases, Zika still poses severe risks because of its effect on pregnant women. When women are infected during gestation, their fetuses can develop malformations such as microcephaly. Microcephalic newborns’ brains do not develop properly and are left with smaller than normal heads. This can lead to intellectual disabilities, poor motor functions, and several other issues.

One example of mosquitos’ ability to spread disease comes from the Acre State in Brazil. For decades, residents lived in the perfect climate for mosquitos, yet there were none to be found. In 2000, it got its first case of Dengue, and only ten years later there were 35,000 cases. Studies link this sudden infection to commercial development. Researchers wrote, “the landscape changes that occurred in the last decade have created favorable conditions for the establishment of dengue virus transmission.” New roads and airstrips provided jobs and economic advancement, but also more mosquitos and hosts for the virus. The increase in human movement caused their capital Rio Branco to go from classification as “dengue-free” to “highest risk” by the Brazilian Ministry of Health.

For more information, please see:

Folha De S.Paulo – Brazil Has at Least 357 Cities at Risk of a Renewed Aedes Linked Outbreak – 29 November 2017

Xinhua Net – Outbreak risks remain in summer though Zika cases down 92 pct in Brazil – 29 November 2017

NPR – Why a Brazilian State Went From 0 Cases of Dengue To 35,000 A Year – 28 November 2017

ICFI – Brazil cuts science budget amid mounting yellow fever threat – 8 November 2017

Author: Emily Green

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