Dried-blood spots: a cost-effective field method for the detection of Chikungunya virus circulation in remote areas.
BACKGROUND
In 2005, there were outbreaks of febrile polyarthritis due to Chikungunya virus (CHIKV) in the Comoros Islands. CHIKV then spread to other islands in the Indian Ocean: La Réunion, Mauritius, Seychelles and Madagascar. These outbreaks revealed the lack of surveillance and preparedness of Madagascar and other countries. Thus, it was decided in 2007 to establish a syndrome-based surveillance network to monitor dengue-like illness.


OBJECTIVE
This study aims to evaluate the use of capillary blood samples blotted on filter papers for molecular diagnosis of CHIKV infection. Venous blood samples can be difficult to obtain and the shipment of serum in appropriate temperature conditions is too costly for most developing countries.


RESULTS
Venous blood and dried-blood blotted on filter paper (DBFP) were collected during the last CHIKV outbreak in Madagascar (2010) and as part of our routine surveillance of dengue-like illness. All samples were tested by real-time RT-PCR and results with serum and DBFP samples were compared for each patient. The sensitivity and specificity of tests performed with DBFP, relative to those with venous samples (defined as 100%) were 93.1% (95% CI:[84.7-97.7]) and 94.4% (95% CI:[88.3-97.7]), respectively. The Kappa coefficient 0.87 (95% CI:[0.80-0.94]) was excellent.


CONCLUSIONS
This study shows that DBFP specimens can be used as a cost-effective alternative sampling method for the surveillance and monitoring of CHIKV circulation and emergence in developing countries, and probably also for other arboviruses. The loss of sensitivity is insignificant and involved a very small number of patients, all with low viral loads. Whether viruses can be isolated from dried blood spots remains to be determined.
Virology Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar. soafy@pasteur.mg
Soa Fy
SF
Andriamandimby
Jean-Michel
JM
Heraud
Laurence
L
Randrianasolo
Jean Théophile
JT
Rafisandratantsoa
Seta
S
Andriamamonjy
Vincent
V
Richard
D000293:Adolescent; D000328:Adult; D018354:Alphavirus Infections / Q000175:diagnosis*; D001769:Blood / Q000821:virology*; D002646:Chikungunya virus / Q000302:isolation & purification*; D003365:Costs and Cost Analysis; D003890:Desiccation / Q000379:methods*; D003906:Developing Countries; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000191:economics / Q000379:methods*; D014773:Virology / Q000379:methods; D055815:Young Adult