this study was conducted as part of epidemiologic surveillance activities of the ministry of public health of the central african republic .
data were obtained through the yellow fever surveillance system and approved by the ministry of health and who .
a suspected case of yellow fever was defined as an acute onset of fever in a patient followed by jaundice within 2 weeks ( 3 ) .
all blood samples from patients with suspected cases were tested at the institut pasteur ( bangui , central african republic ) ( ipb ) for yellow fever virus  specific igm by using the elisa developed by the us centers for disease control and prevention ( 4 ) .
positive samples were sent to the regional reference laboratory at the institut pasteur in dakar , senegal , where a plaque - reduction neutralization test ( prnt ) was performed for case confirmation .
a suspected yellow fever case was ruled out if elisa or prnt results were negative . when a suspected case was not ruled out by elisa ,
health authorities were informed and an investigation was conducted so that vaccination could be implemented without delay if the case was confirmed .
each intermediate step was studied : collection ( from onset of jaundice to blood sample collection ) , field storage ( from sample collection to shipping ) , transportation ( from shipping to reception at ipb ) and testing ( from reception of sample to elisa result ) .
survival analysis was performed to determine how the following factors affected time to confirmed cases : age , sex , onset during the rainy season ( may 1october 31 ) , province of residence , history of vaccination against yellow fever , and year of onset . because the proportional hazard assumption was not verified for several variables , we used a parametric survival model and assumed a log - normal distribution of event times to estimate mutually adjusted time ratios .
data were analyzed with stata software version 11.0 ( statacorp lp , college station , tx , usa ) maps were drawn with arcgis version 10.1 ( esri , redlands , ca , usa ) . during january 2007july 2012 , a total of 3,220 suspected cases of yellow fever were reported to ipb ( technical appendix figure 1 ) .
suspected cases were reported in all provinces but mostly in bangui ( 32.7% ) and in neighboring ombella mpoko province ( 24.7% ) ( technical appendix figure 2 ) .
median age of patients with suspected cases was 21 years ( interquartile range 1030 years ) and 57.5% were men .
only 21.9% reported having been vaccinated against yellow fever virus within the previous decade ( table 1 ) .
mean delay was 9.9 days ( 95% ci 9.510.2 days ) for blood sample collection , 1.5 days ( 95% ci 1.41.6 days ) for field storage , 1.1 days ( 95% ci 1.01.1 days ) for transportation , and 4.2 days ( 95% ci 4.14.3 days ) for testing .
detection of yellow fever ( figure 1 , panel a ) and delay for blood collection ( figure 1 , panels b  e ) were shortest in 2009 .
temporal pattern of mean time ( delay between date of onset of jaundice reported by the patient and date of an elisa result ) for a ) yellow fever surveillance , b ) blood sample collection , c ) field storage of samples , d ) transportation of samples , and e ) testing of samples , central african republic , 20072012 .
mean time until blood collection was shortest in bangui ( 14.8 days ) and surrounding areas and longest in mbomou ( 26.2 days ) ( figure 2 , panel a ) .
mean delay for blood sample collection was shorter in eastern and northern regions of the country and longer in central and western regions ( figure 2 , panel b ) .
east gradient and ranged from 0.1 days in bangui to 4.9 days in haut mbomou ( figure 2 , panel d ) . a longer period to blood sample testing for the eastern part of the country was related to longer times of field storage and transportation ( figure 2 , panels c , d ) .
mean time for testing remained stable at 45 days ( figure 2 , panel e ) .
spatial pattern of mean time ( delay between date of onset of jaundice reported by the patient and date of an elisa result for a ) yellow fever surveillance , b ) mean time for blood sample collection , c ) mean time for field storage of samples , d ) mean time for transportation of samples , and e ) mean time for testing of samples , by province , central african republic , 20072012 .  
province of residence and year of onset were associated with a shorter period to diagnosis ( p<0.001 ) ( table 2 ) .
adjusted time ratios are from a parametric survival model assuming log - normal distribution of the event times .
timeliness was defined as the delay between the date of onset of jaundice ( reported by the patient ) and the date of elisa result .
a total of 55 yellow fever cases were confirmed and 11 case - patients died .
of the confirmed case - patients , 22 ( 40.0% ) were 1524 years of age , 35 ( 63.6% ) were male , and for 13 ( 23.6% ) date of vaccination against yellow fever virus was unknown .
age and history of vaccination differed between patients who had confirmed yellow fever cases and those who did not ( table 1 ) .
this study shows that in the central african republic , a country with limited health care and transportation facilities , confirmation of a yellow fever case takes 23 weeks .
approximately 10 days ( 60% of the delay ) are required from the onset of symptoms to blood collection . a fast time to case confirmation
was observed in 2009 , which was largely caused by a decrease in time required for blood collection , could be related to greater public awareness resulting from a yellow fever outbreak in ombella mpoko and lobaye ( 5 ) and from a large outbreak of hepatitis e. this study showed an unexpected association between younger age and more rapid time to diagnosis , which was caused mainly by a shorter delay until blood collection , suggesting that parents have their children tested earlier .
these 2 results indicate that the delay to blood collection could be reduced by better awareness of the population to the need for testing when they have symptoms compatible with yellow fever .
the 45 days of delay until testing is below the threshold of 7 days recommended by who
. however , it could be decreased by implementation of a method of yellow fever detection ( bioplex technology ; biorad laboratories , hercules , ca , usa ) , which is now in progress at ipb . the need for confirmation by prnt might delay vaccination because of time necessary for transportation of samples to dakar and testing .
the central african republic is landlocked and surrounded by countries to which yellow fever is endemic ( 6 ) .
thus , prnt for this region could be implemented at ipb , where biosafety level 3 facilities are functional .
delays in reporting cases observed in this study are consistent with time between onset of symptoms of yellow fever in index case - persons and in persons infected by them , which is estimated to be 2 weeks ( 7 ) .
a comparison of delays found in this study with those in other countries would be helpful .
 during january 2007july 2012 , a total of 3,220 suspected yellow fever cases were reported in the central african republic ; 55 were confirmed and 11 case - patients died . 
 mean delay between onset of jaundice and case confirmation was 16.6 days . 
 delay between disease onset and blood collection could be reduced by increasing awareness of the population . 
The Study
Conclusions
None