@article{fdi:010080630,
  title = {{A} timed tally counter for microscopic examination of thick blood smears in malaria studies},
  author = {{N}uel, {G}. and {G}arcia, {A}ndr{\'e}},
  editor = {},
  language = {{ENG}},
  abstract = {{B}ackground {D}espite many technological advances for malaria parasite detection (e.g. high resolution image acquisition), microscopic reading of thick blood smear ({TBS}) remains the gold standard. {E}ven though available in low technology environment, the microscopy of {TBS} is slow and time consuming. {M}oreover microscopy may induce errors at many levels and has no quality control. {M}ethods {A} electronic extension of the mechanical tally counter is proposed. {I}n addition to the counting process it includes the process of counting itself that relies on the time elapsed between two successive pressures of the counting button leading to a timed tally counter ({TTC}). {T}he microscopist performs the reading with the specific instruction starting by counting, in each high power fields, leucocytes first and then parasites. {T}he time-stamp of all pressures of counting buttons are recorded along with the nature of the count. {T}he data are recorded internally in {CSV} format and are exportable. {T}he detection of {HPF}s locations and leukocyte/parasite counts per {HPF}s is performed through a hidden semi-{M}arkov model (with outliers) allowing both to take into account the known distribution of leukocyte per {HPF}s (using a negative binomial distribution) and the pauses and hesitation of the microscopist during the reading. {P}arameters are estimated via the expectation-maximization algorithm. {H}yper-parameters are calibrated using expert annotations. {F}orward/backward recursions are used to obtain the {HPF}s locations. {R}esults {T}his approach provides richer data at no extra cost. {I}t has been demonstrated that the method can derive parasites per {HPF}, leukocytes per {HPF}, and parasite/leukocyte ratio with robust non-parametric confidence intervals. {M}oreover a direct digital data entry leads to a less expensive process and decreased time-consuming and error-prone manual data entry. {L}astly the {TTC} allows detecting possible protocol break during reading and prevents the risk of fraud. {D}iscussion and conclusion {I}ntroducing a programmed digital device in the data acquisition of {TBS} reading gives the opportunity to develop easily new (possible adaptive) reading protocols that will be easily followed by the reader since they will be embedded directly in the device. {W}ith the {TTC} the reader only has to read {HPF}s, counting leukocytes first and parasites second, and the counter will beep when the protocol is completed.},
  keywords = {{M}alaria ; {P}arasite density ; {M}icroscope ; {Q}uality control ; {T}imed tally counter},
  booktitle = {},
  journal = {{M}alaria {J}ournal},
  volume = {20},
  numero = {1},
  pages = {6 [11 p.]},
  year = {2021},
  DOI = {10.1186/s12936-020-03530-z},
  URL = {https://www.documentation.ird.fr/hor/fdi:010080630},
}