Earlier in May, researchers at the Federal University of Rio
de Janeiro announced that they had discovered patients infected by the Mayaro virus
in the state of Rio de Janeiro.
What is Mayaro virus? It’s related to Chikungunya, and
produces very similar symptoms - fevers and intense muscular pains. Mayaro had
previously been thought to be restricted to areas of the Amazon forest, where
it is transmitted primarily by the forest mosquito Haemagogas janthinomys.
However, the recent cases followed analysis of 3 workers in
Niteroi, a city next to Rio, diagnosed with Chikungunya, but whose subsequent
tests were negative. Significantly, none of the patients had been to Amazonia, implying
Mayaro was circulating in the local population.
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| James Gathany - PHIL, CDC, Public Domain, |
The route of transmission in these cases is unknown, and one
possibility is that the virus was again carried by Haemagogas janthinomys, which although traditionally a mosquito of
the Amazon, has been detected in forest areas near cities in the south of
Brazil, and has been implicated in an outbreak of Yellow Fever in 2016 (de
Abreu et al 2019).
There is however a more worrying possibility. It has been previously
reported (Long et al 2011) that Mayaro
can be transmitted by the mosquito Aedes
aegypti, which is both much more common in urban areas, and more
homophagous.
There are doubts about how good a vector Aedes aegypti would be for Mayaro
(Brustolin et al 2018), and it should
be stressed that Aedes aegypti was
infected in the laboratory, and no wild caught individuals have yet been found
with the disease. However, if it does turn out to be an urban vector this is a
matter for serious concern.
Sources
Pesquisadores da UFRJ anunciam que descobriram virus mayaro no
estado do Rio. Globo. 16 May 2019.
Virus Mayaro, transmitido pelo Aedes aegypti, chega ao Rio.
Globo. 17 May 2019. https://globoplay.globo.com/v/7622100/
Anopheles mosquitoes may drive invasion and transmission of
Mayaro virus across geographically diverse regions. Brustolin, M. et al.
(2018). PLOS Neglected Tropical Diseases 12(11), e0006895.
Haemagogus
leucocelaenus and Haemagogus
janthinomys are the primary vectors in the major yellow fever outbreak in
Brazil, 2016–2018. De Abreu et al. (2019). Emerging Microbes & Infections,
8, 218-231.
Experimental transmission of Mayaro virus by Aedes aegypti. Long, K.C. (2011). Am J
Trop Med Hyg., 85(4), 750-757.
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