Tuesday 27 September 2016

Mayaro virus: a primer and a tree...

Mayaro virus (MAYV) is a member of the Family Togaviridae. Genetically its divided into two genotypes, "D" (widely Dispersed), "N" (?New) and "L" (Limited) - shown in the tree below.

MAYV is an arthropod-borne virus (arbovirus) that can cause Mayaro fever. 

Disease may can include 4 days of viraemia, a rash that may appear after a 3-5 day fever, headache, photophobia, inguinal lymphadenopathy, myalgia, vomiting, diarrhoea and arthralgia which can affect ankles, wrists and toes and less often, other joints. Joint pain may continue for weeks and maybe very painful. 

Disease is clinically similar to that due to primary dengue virus or chikungunya virus infection. MAYV was first described in 1954 after its discovery in in Mayaro County, Trinidad.[2,3]

Recently, a MAYV infection by a rare member of the L lineage was identified in a dengue virus coinfection in a child in Haiti (sequence shown in bold below) during investigations of sera collected from children with unspecified fever between May 2014 and February 2015.[1]
Mayaro viruses and other Genus Alphavirus and 
Genus Rubivirus complete genome sequences. 
Aligned using MAAFT in Geneious v7. 
Tree made using Mega v7.
Click on image to enlarge

While the Haitian case triggered the usual media sirens, this is a virus well worth watching - and testing for. 

An incredibly prescient 2010 review by Weaver & Reisen on future threats is well worth a read.[4] 

Findings of infection and occasional flaccid paralysis in suckling mice (adult mice were not obviously infectable) that had been injected intracerebrally with low passage virus preparations [2,5] - well, in the new Zika virus reality, it really wouldn't pay to underestimate the potential of yet another tropical virus would it?

Human cases of MAYV infection have most often been reported in working males in forested areas near rivers in countries from Mexico down to Bolivia. All of that knowledge is, of course, based on visible disease outbreaks. I have yet to read every paper, but so  far I have not seen anything that delves deeply into rates of mild or asymptomatic disease. 

MAYV was also isolated in 1967 (reported in 1974 [6]) from a migrating bird (orchard oriole - Icterus spurius) detected in Louisiana, USA. Because it was such a rare event, the authors concluded that these birds probably didn't play a role as natural hosts to MAYV. Apparently it was found in a lizard too - but I'm still chasing down that paper.[7]

  1. http://wwwnc.cdc.gov/eid/article/22/11/16-1015_article
  2. Casals J, Whitman L. Mayaro virus: a new human disease agent. I. Relationship to other arbor viruses. Am J Trop Med Hyg. 1957;6(6):1004-11. PubMed PMID: 13487972.
  3. Anderson CR, Downs WG, Wattley GH, Ahin NW, Reese AA. Mayaro virus: a new human disease agent. II. Isolation from blood of patients in Trinidad, B.W.I. Am J Trop Med Hyg. 1957;6(6):1012-6. PubMed PMID: 13487973.
  4. Scott C. Weaver and William K. Reisen. Present and Future Arboviral Threats. Antiviral Res.
  5. Schmidt JR, Gajdusek DC, Schaffer M, Gorrie RH. Epidemic jungle fever among Okinawan colonists in the Bolivian rain forest. II. Isolation and characterization of Uruma virus, a newly recognized human pathogen. Am J Trop Med Hyg. 1959;8(4):479-87. PubMed PMID: 13670375.
  6. Charles H. Calisher, Ph.D.; Ernest0 Gutikez V., M.D.; Kathryn S. C. Maness, B.S., and Rexford D. Lord, SC.D. ISOLATION OF MAYARO VIRUS FROM A MIGRATING BIRD CAPTURED IN LOUISIANA IN 1967. Bull Pan Am Health Organ. 1974;8(3):243-8.
  7. Woodall JP Virus research in Amazonia. Atas do Simposia sobre a Biota Amazónia 1967; 6(Patologia):31–63.
  8. Albert J. Auguste, Jonathan Liria, Naomi L. Forrester, Dileyvic Giambalvo, Maria Moncada, KC Long, D Morón, N de Manzione, RB Tesh, ES Halsey, TJ Kochel, R Hernandez, J-C Navarro, SC Weaver. Evolutionary and Ecological Characterization of Mayaro Virus Strains Isolated during an Outbreak, Venezuela, 2010

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