Evaluation of yellow fever surveillance in Chad, 2015-2020

The present study was conducted to determine the seroprevalence of yellow fever virus in patients with clinical signs of febrile jaundice giving suspicion of yellow fever and to evaluate diagnostic techniques for surveillance of yellow fever in the Republic from Chad. From January 2015 to July 2020, an observational study of virological markers was conducted in jaundice patients in Chad. Of the 1730 patients included in this study, a seroprevalence of 0.28% of yellow fever virus was determined. The distribution of pathogens responsible for diseases associated with yellow fever was: 49.47% (Plasmodium falciparum), 2% (hepatitis E virus), 4.62% (hepatitis C virus), and 29.00% (hepatitis virus B), respectively. Discrepancies in the results between the regional reference laboratories and the national laboratory of the Republic of Chad were observed. All genders and age groups were affected. Of the 1730 samples taken, 55.49% were female and 44.51% male (p = 0.01, a significant difference in favor of the female sex). The male/female sex ratio was 1.25. This study, the first, made it possible to determine the rate of the yellow fever virus in the absence of an outbreak in forest areas and with heavy rainfall and to evaluate the MAC-ELISA-CDC techniques used between the national laboratory of the Republic of Chad and those regional references. It was recommended that real-time polymerization chain reaction techniques be made available to national laboratories and reagents from the same manufacturing company in order to carry out effective monitoring of yellow fever.