Mayaro virus disease - French Guiana, France
Disease Outbreak News
25 October 2020
On 13 October 2020, the French health authorities officially reported 13 laboratory-confirmed cases of Mayaro fever in French Guiana, France.
In September 2020, the Institut Pasteur de la Guyane (IPG) (member of the French National Reference Laboratory for arboviruses) identified two cases of Mayaro virus infection (MAYV) confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) and one probable case found positive for Mayaro antibodies. The case-patients presented dengue-like symptoms and joint pains, and tested negative for dengue by RT-PCR.
This unexpected diagnosis led to a further retrospective search for additional cases of Mayaro fever among patients with dengue-like symptoms who tested negative for dengue. Reverse transcriptase polymerase chain reaction was performed on samples collected between 15 July and 15 September, at laboratories mainly located in Cayenne area. These blood samples were collected from patients with dengue-like symptoms , who had tested negative for dengue within five days after the onset of symptoms. In total (including the first detections and retrospective search) IPG identified 11 cases of Mayaro fever by RT-PCR out of 79 samples tested. These cases were reported on 21 September 2020.
On 2 October and 8 October 2020, two additional confirmed cases of Mayaro fever were reported by the Institute Pasteur de la Guyane in Cayenne, leading to a total of 13 confirmed cases among 97 tested samples between 15 July and early October. The onset of symptoms for the 13 confirmed cases ranged from 18 July to 29 September 2020. Of the 13 confirmed cases, 11 lived in the urban coastal area including nine from Cayenne area (Cayenne: 1, R?mire: 4, Matoury: 4), one from Kourou, and one from Montsinery-Tonnegrande. Only two cases lived in a rural/sylvatic area, both in Roura (including one in the village of Cacao, located further in the interior). The age of these cases ranged between 11 to 68 years old (median = 40 years old) and the male to female sex ratio was 1.2:1.
Mayaro virus (MAYV) has been known to circulate in French Guiana since 1998, but the number of RT-PCR detections of MAYV by IPG between 2017 and 2019 added up to between 1 to 3 confirmed cases annually, detected from 150 to over 600 samples tested every year. As per the testing criteria for MAYV, blood samples were collected within 5 days of the onset of dengue-like symptoms and found negative for dengue virus.
Detection of 13 confirmed cases within less than 3 months is thus unusual. Furthermore, MAYV is mainly transmitted through a sylvatic cycle and transmission in urban settings has been sparsely described. It is therefore atypical that 11 out of 13 (85%) identified cases of Mayaro fever resided in an urban area.
MAYV vector (Haemagogus species mosquitoes) is also the vector of the sylvatic cycle of yellow fever virus and is present in wild or rural habitats of the region of the Americas and the Caribbean. MAYV has been isolated from other genera of mosquitoes, including Culex,Mansonia , Aedes, Psorophora , and Sabethes .
Epidemiological investigation is ongoing in particular to document the travel history of the cases and to determine whether the infections were contracted in forest areas or if the transmission through an urban cycle may be suspected.
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Disease Outbreak News
25 October 2020
On 13 October 2020, the French health authorities officially reported 13 laboratory-confirmed cases of Mayaro fever in French Guiana, France.
In September 2020, the Institut Pasteur de la Guyane (IPG) (member of the French National Reference Laboratory for arboviruses) identified two cases of Mayaro virus infection (MAYV) confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) and one probable case found positive for Mayaro antibodies. The case-patients presented dengue-like symptoms and joint pains, and tested negative for dengue by RT-PCR.
This unexpected diagnosis led to a further retrospective search for additional cases of Mayaro fever among patients with dengue-like symptoms who tested negative for dengue. Reverse transcriptase polymerase chain reaction was performed on samples collected between 15 July and 15 September, at laboratories mainly located in Cayenne area. These blood samples were collected from patients with dengue-like symptoms , who had tested negative for dengue within five days after the onset of symptoms. In total (including the first detections and retrospective search) IPG identified 11 cases of Mayaro fever by RT-PCR out of 79 samples tested. These cases were reported on 21 September 2020.
On 2 October and 8 October 2020, two additional confirmed cases of Mayaro fever were reported by the Institute Pasteur de la Guyane in Cayenne, leading to a total of 13 confirmed cases among 97 tested samples between 15 July and early October. The onset of symptoms for the 13 confirmed cases ranged from 18 July to 29 September 2020. Of the 13 confirmed cases, 11 lived in the urban coastal area including nine from Cayenne area (Cayenne: 1, R?mire: 4, Matoury: 4), one from Kourou, and one from Montsinery-Tonnegrande. Only two cases lived in a rural/sylvatic area, both in Roura (including one in the village of Cacao, located further in the interior). The age of these cases ranged between 11 to 68 years old (median = 40 years old) and the male to female sex ratio was 1.2:1.
Mayaro virus (MAYV) has been known to circulate in French Guiana since 1998, but the number of RT-PCR detections of MAYV by IPG between 2017 and 2019 added up to between 1 to 3 confirmed cases annually, detected from 150 to over 600 samples tested every year. As per the testing criteria for MAYV, blood samples were collected within 5 days of the onset of dengue-like symptoms and found negative for dengue virus.
Detection of 13 confirmed cases within less than 3 months is thus unusual. Furthermore, MAYV is mainly transmitted through a sylvatic cycle and transmission in urban settings has been sparsely described. It is therefore atypical that 11 out of 13 (85%) identified cases of Mayaro fever resided in an urban area.
MAYV vector (Haemagogus species mosquitoes) is also the vector of the sylvatic cycle of yellow fever virus and is present in wild or rural habitats of the region of the Americas and the Caribbean. MAYV has been isolated from other genera of mosquitoes, including Culex,Mansonia , Aedes, Psorophora , and Sabethes .
Epidemiological investigation is ongoing in particular to document the travel history of the cases and to determine whether the infections were contracted in forest areas or if the transmission through an urban cycle may be suspected.
READ MORE
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