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. 2021 Jun 18;21(1):586.
doi: 10.1186/s12879-021-06266-6.

Hospital-based prospective study of pertussis in infants and close contacts in Tehran, Iran

Gaelle Noel #  1 , Masoumeh Nakhost Lotfi #  2 , Sajedeh Mirshahvalad  2 , Sedaghatpour Mahdi  2 , David Tavel  3 , Seyed M Zahraei  4 , Roxana Mansour Ghanaie  5 , Tahereh Heidary  6 , Aliahmad Goudarzi  7 , Azardokht Kazemi  8 , Abdollah Karimi  5 , Alireza Nateghian  6 , Mohand Ait-Ahmed  9 , Nicole Guiso #  10 , Fereshteh Shahcheraghi #  2 , Fabien Taieb #  10   11
Affiliations

Hospital-based prospective study of pertussis in infants and close contacts in Tehran, Iran

Gaelle Noel et al. BMC Infect Dis. .

Abstract

Background: Pertussis remain a global health concern, especially in infants too young to initiate their vaccination. Effective vaccination and high coverage limit the circulation of the pathogen, yet duration of protection is limited and boosters are recommended during a lifetime. In Iran, boosters are given at 18 months and 6 years old using whole pertussis vaccines for which efficacy is not known, and pertussis surveillance is scant with only sporadic biological diagnosis. Burden of pertussis is not well understood and local data are needed.

Methods: Hospital-based prospective study implementing molecular laboratory testing in infants aged ≤6 months and presenting ≥5 days of cough associated to one pertussis-like symptom in Tehran. Household and non-household contact cases of positive infants were evaluated by comprehensive pertussis diagnosis (molecular testing and serology) regardless of clinical signs. Clinical evaluation and source of infection were described.

Results: A total of 247 infants and 130 contact cases were enrolled. Pertussis diagnosis result was obtained for 199 infants and 104 contact cases. Infant population was mostly < 3 months old (79.9%; 157/199) and unvaccinated (62.3%; 124/199), 20.1% (40/199) of them were confirmed having B. pertussis infection. Greater cough duration and lymphocyte counts were the only symptoms associated to positivity. Half of the contact cases (51.0%; 53/104) had a B. pertussis infection, median age was 31 years old. A proportion of 28.3% (15/53) positive contacts did not report any symptom. However, 67.9% (36/53) and 3.8% (2/53) of them reported cough at inclusion or during the study, including 20.8% (11/53) who started coughing ≥7 days before infant cough onset. Overall, only five samples were successfully cultured.

Conclusion: These data evidenced the significant prevalence of pertussis infection among paucy or poorly symptomatic contacts of infants with pertussis infection. Widespread usage of molecular testing should be implemented to identify B. pertussis infections.

Keywords: Contact; Diagnosis; Infant; Infection; Pertussis; Vaccine compliance; Whole-cell vaccine.

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Conflict of interest statement

The authors have declared that no conflict of interests exist.

Figures

Fig. 1
Fig. 1
Flow chart of index (a) and contact (b) cases included in the analysis
Fig. 2
Fig. 2
Distribution of primary (a) and secondary (b) cases with respect to the index case among positive contacts. yo, years old
See this image and copyright information in PMC

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