Environmental Surveillance of Poliovirus and Non-polio Enteroviruses in Iran, 2017-2023: First Report of Imported Wild Poliovirus Type 1 Since 2000.

In Iran, which is at high risk of the Wild Poliovirus (WPV) and Vaccine-Derived Poliovirus (VDPV) importation due to its neighborhood with two polio endemic countries, Pakistan and Afghanistan, Environmental Surveillance (ES) was established in November 2017. Sistan-Balouchestan province was chosen for the ES due to its vicinity with Pakistan and Afghanistan. Five sewage collection sites in 4 cities (Zahedan, Zabol, Chabahar and Konarak) were selected in the high-risk areas. Since the establishment of ES in November 2017 till the end of 2023, 364 sewage specimens were collected and analyzed. The ES detected polioviruses which have the highest significance for polio eradication program, that is, Wild Poliovirus type 1 (WPV1) and Poliovirus type 2 (PV2). In April and May 2019, three of 364 (0.8%) sewage specimens from Konarak were positive for imported WPV1. According to phylogenetic analysis, they were highly related to WPV1 circulating in Karachi (Sindh province) in Pakistan. PV2 was also detected in 5.7% (21/364) of the sewage specimens, most of which proved to be imported from the neighboring countries. Of 21 isolated PV2s, 7 were VDPV2, of which 5 proved to be imported from the neighboring countries as there was VDPV2 circulating in Pakistan at the time of sampling, and 2 were ambiguous VDPVs (aVDPV) with unknown source. According to the findings of this study, as long as WPV1 and VDPV2 outbreaks are detected in Iran's neighboring countries, there is a definite need for continuation and expansion of the environmental surveillance.

Multicenter Study of Rotavirus Infection, Diversity of Circulating Genotypes and Clinical Outcomes in Children ≤5 Years Old in Iran.

BACKGROUND: To determine the epidemiology of rotavirus group A (RVA) infection in symptomatic children, and analyze genotype diversity in association with clinical characteristics, geographical and seasonal changes. METHODS: The stool samples of symptomatic children 5≥ years old were collected from 5 different hospitals during December 2020 and March 2022. Rotavirus stool antigen test was done and G and P genotypes of the positive samples were determined. Associations of the infection and genotype diversity with demographical and clinical data were assessed by statistical methods. RESULTS: RVA infection was detected in 32.1% (300/934) of the patients (Ranges between 28.4% and 47.4%). An inverse association with age was detected, where the highest frequency was measured in children ≤12 months of age (175/482, 36.3%). The infection was more frequent during winter (124/284, 43.7%) and spring (64/187, 34.2%). Children who were exclusively fed with breast milk showed a lower rate of infection (72/251, 28.6%). Among the 46 characterized genotypes (17 single- and 29 mixed-genotype infections), G1P[8] and G9P[4] were more frequently detected in children <36 (67/234, 28.63%) and 36-60 (7/24, 29.16%) months of age children, respectively. A seasonal diversity in the circulating genotypes was detected in different cities. Children with G1P[8], G1P[6], and mixed-genotype infection experienced a shorter duration of hospitalization, and a higher frequency of nausea and severe diarrhea, respectively. CONCLUSIONS: In this study high frequency of RVA infection was detected in symptomatic children in Iran. Moreover, genotype diversity according to geographic area, seasons, age groups, and clinical features of disease was detected.

Molecular typing of enteroviruses and parechoviruses in acute flaccid paralysis patients in Iran in 2019.

Enteroviruses (EVs) and parechoviruses (PeVs) are among the viral pathogens that can cause acute flaccid paralysis (AFP). There is not sufficient information about direct detection of EVs and PeVs in AFP patients in Iran. The aim of this study was to conduct a one-year study for direct detection and molecular typing of EVs and PeVs from stool samples of AFP patients in Iran. One hundred stool samples from polio-negative AFP patients who were referred to the Iran National Polio Laboratory were randomly chosen and analyzed during 2019. A one-step TaqMan probe-based real-time RT-PCR assay targeting the 5'-untranslated region (5' -UTR) was used to screen for EVs and PeVs. All positive samples were genotyped by direct sequencing, targeting the VP1 region of the genome. In total, twelve (12%) and four (4%) stool samples from polio-negative AFP children were positive for EVs and PeVs, respectively. Sequence analysis revealed the presence of echovirus 2 (E2), echovirus 13 (E13), echovirus 25 (E25), echovirus 30 (E30), coxsackievirus A2 (CVA2), coxsackievirus A9 (CVA9), coxsackievirus A16 (CVA16), human enterovirus A76 (HEV-A76), and human parechovirus 1 (HPeV1) in children with AFP-like symptoms. Phylogenetic analysis showed that E2 strains clustered together with the strains circulating in the Netherlands during 2014, whereas the PeV strains belonged to different lineages. This study demonstrates that different EV types are associated with AFP cases in Iran. However, the frequency of association of PeVs with AFP cases appears to be low.

Epidemiology of Guillain-Barré Syndrome in Iranian Children Aged 0-15 Years (2008-2013).

OBJECTIVE: Guillain-Barré Syndrome (GBS) is an acute inflammatory polyneuropathy characterized by a rapid progressive symmetric weakness. The GBS is the most common cause of acute flaccid paralysis (AFP) in most parts of the world. This study was carried out to investigate the epidemiological features of GBS in Iranian children. MATERIALS & METHODS: The data were extracted using the AFP surveillance system that is a national screening program to detect all cases of AFP aged 0-15 years around the country. National Population Statistics data and AFP demographic data during 2008-2013 intervals were obtained from the relevant authorities in the Ministry of Health in Iran. The GBS cases were then extracted from the aforementioned database. The Chi-square test and Fisher's exact test were used for statistical analysis. RESULTS: A total of 1884 cases of GBS were identified in the study period, and the average annual incidence rate was 1.72 per 100,000 individuals. The highest incidence rate was within the range of 0-5 years. There was no statistically significant relationship between the incidence of GBS and the season in the whole country. CONCLUSION: High costs of GBS treatment, morbidity and occasional mortality, and number of new cases, which is estimated to be approximately 300 individuals per year, need the particular attention of the health system.

Effect of Haemophilus influenzae Type b Vaccination on Nasopharyngeal Carriage Rate in Children, Tehran, 2019.

BACKGROUND: Haemophilus influenzae (H. influenzae) strains, which commonly reside as commensals within the human pharynx and can remain as an asymptomatic carrier, but become invasive leading to pneumonia, septic arthritis, or meningitis. The Pentavac (pentavalent vaccine, manufactured by India, SII (DTwP-HepB-Hib)) was introduced to the Iranian National Immunization Plan in November 2014. The aim of this study is to investigate H. influenzae type b (Hib) carrier rate among children under 6 years old in Tehran. METHODS: This cross-sectional study was performed on 902 children including vaccinated/unvaccinated in the age of 6 months to 6 years, in Tehran. Sampling was performed from July 2019 to September 2019. Nasopharyngeal samples were taken from children by sterile swab. The PCR method was used to extract DNA. Then, all H. influenzae isolates were initially confirmed by molecular tests. BexA was used to distinguish typeable H. influenzae strains from nontypeable Haemophilus influenzae (NTHi). RESULTS: A total of 902 children were enrolled in the study: 452 were female (51%). H. influenzae carriage rate was 267 (29%), of that 150 samples (16.6%) were typeable. The nasopharyngeal Hib carrier rate in the children was 2.6% (24/902). 262 cases did not receive Hib vaccine. Analysis in nonnursery's children aged 4 to 6 (unvaccinated) years showed that the lower educational level of father, mother, and family number correlated with increased odds of colonization of children with Hib. CONCLUSION: Our findings showed a significant decrease (60%) in the overall Hib nasopharyngeal carriage in healthy children under six years after 5 years after the start of Hib vaccination.

Molecular characterization of non-polio enteroviruses isolated from children with acute flaccid paralysis in IRAN, 2015-2018.

In addition to polioviruses, non-polio enteroviruses (NPEVs) are frequently isolated from patients with acute flaccid paralysis (AFP) worldwide. In polio-free countries, there have been expectations that with disappearing wild poliovirus from the community, the rate of AFP would decrease, but the increasing number of AFP cases proved this notion to be wrong. There are speculations that NPEVs might be the cause of increasing AFP rate. The aim of this study was to investigate frequency, genetic diversity, circulation patterns of NPEVs isolated from AFP cases in Iran from 2015 to 2018. Fifty-three NPEVs were isolated from stool specimens of AFP cases during four years of AFP surveillance. Nested PCR and VP1 sequencing revealed 20 NPEV types in which Echovirus 3 (13.2%), Echovirus 6 (13.2%), Echovirus 7 (7.5%), Echovirus 13 (7.5%) and Echovirus 21 (7.5%) were the most frequent. Coxsackie B viruses were isolated for the first time in AFP cases in Iran. The phylogenetic analysis of Echovirus 3 and Echovirus 6 revealed that Iranian echovirus strains belonged to the same cluster, indicating these viruses have been circulating in Iran for a long time. Compared to global Echovirus 3 and Echovirus 6 references, Echovirus 3 and Echovirus 6 strains detected in this study were closely related to Indian and Malaysia strains, respectively. The results of this study demonstrated a wide variety of NPEV types in Iranian patients, some of which had not been reported in previous studies. Moreover, this study highlights the need for NPEV surveillance in AFP cases.

Vaccine-Derived Poliovirus Infection among Patients with Primary Immunodeficiency and Effect of Patient Screening on Disease Outcomes, Iran.

Patients with immunodeficiency-associated vaccine-derived poliovirus (iVDPV) are potential poliovirus reservoirs in the posteradication era that might reintroduce polioviruses into the community. We update the iVDPV registry in Iran by reporting 9 new patients. In addition to national acute flaccid paralysis surveillance, cases were identified by screening nonparalyzed primary immunodeficiency (PID) patients. Overall, 23 iVDPV patients have been identified since 1995. Seven patients (30%) never had paralysis. Poliovirus screening accelerated the iVDPV detection rate in Iran after 2014.The iVDPV infection rate among nonparalyzed patients with adaptive PID was 3.1% (7/224), several folds higher than previous estimates. Severe combined immunodeficiency patients had the highest risk for asymptomatic infection (28.6%) compared with other PIDs. iVDPV2 emergence has decreased after the switch from trivalent to bivalent oral poliovirus vaccine in 2016. However, emergence of iVDPV1 and iVDPV3 continued. Poliovirus screening in PID patients is an essential step in the endgame of polio eradication.

Enteroviruses and Adenoviruses in stool specimens of paralytic children- can they be the cause of paralysis?

BACKGROUND AND OBJECTIVES: Acute flaccid paralysis (AFP) is a complicated clinical syndrome with a wide range of potential etiologies. Several infectious agents including different virus families have been isolated from AFP cases. In most surveys, Non-polio Enteroviruses (NPEVs) have been detected as main infectious agents in AFP cases; however, there are also some reports about Adenovirus isolation in these patients. In this study, NPEVs and Adenoviruses in stool specimens of AFP cases with or without Residual Paralysis (RP) with negative results for poliovirus are investigated. MATERIALS AND METHODS: Nucleic acid extractions from 55 AFP cases were examined by nested PCR or semi-nested PCR with specific primers to identify NPEVs or Adenoviruses, respectively. VP1 (for Enteroviruses) and hexon (for Adenoviruses) gene amplification products were sequenced and compared with available sequences in the GenBank. RESULTS: From 55 fecal (37 RP+ and 18 RP-) specimens, 7 NPEVs (12.7%) (2 cases in RP+) and 7 Adenoviruses (12.7%) (4 cases in RP+) were identified. Echovirus types 3, 17 and 30, Coxsackie virus A8, and Enterovirus 80 were among NPEVs and Adenoviruses type 2 and 41 were also identified. CONCLUSION: Our finding shows that NPEVs and Adenoviruses may be isolated from the acute flaccid paralyses but there is no association between the residual paralyses and virus detection.

Vaccine-Derived Polioviruses and Children with Primary Immunodeficiency, Iran, 1995-2014.

Widespread use of oral poliovirus vaccine has led to an ≈99.9% decrease in global incidence of poliomyelitis (from ≈350,000 cases in 1988 to 74 cases in 2015) and eradication of wild-type poliovirus serotypes 2 and 3. However, patients with primary immunodeficiency might shed vaccine-derived polioviruses (VDPVs) for an extended period, which could pose a major threat to polio eradication programs. Since 1995, sixteen VDPV populations have been isolated from 14 patients with immunodeficiency in Iran. For these patients, vaccine-associated paralysis, mostly in >1 extremity, was the first manifestation of primary immunodeficiency. Seven patients with humoral immunodeficiency cleared VDPV infection more frequently than did 6 patients with combined immunodeficiencies. Our results raise questions about manifestations of VDPVs in immunodeficient patients and the role of cellular immunity against enterovirus infections. On the basis of an association between VDPVs and immunodeficiency, we advocate screening of patients with primary immunodeficiency for shedding of polioviruses.

Cost-effectiveness analysis of the introduction of rotavirus vaccine in Iran.

BACKGROUND: Although the mortality from diarrheal diseases has been decreasing dramatically in Iran, it still represents an important proportion of disease burden in children <5 years old. Rotavirus vaccines are among the most effective strategies against diarrheal diseases in specific epidemiological conditions. This study aimed to evaluate the cost-effectiveness of the introduction of rotavirus vaccine (3 doses of pentavalent RotaTeq (RV5)) in Iran, from the viewpoints of Iran's health system and society. METHODS: The TRIVAC decision support model was used to calculate total incremental costs, life years (LYs) gained, and disability-adjusted life years (DALYs) averted due to the vaccination program. Necessary input data were collected from the most valid accessible sources as well as a systematic review and meta-analysis on epidemiological studies. We used WHO guidelines to estimate vaccination cost. An annual discount rate of 3% was considered for both health gain and costs. A deterministic sensitivity analysis was performed for testing the robustness of the models results. RESULTS: Our results indicated that total DALYs potentially lost due to rotavirus diarrhea within 10 years would be 138,161, of which 76,591 could be prevented by rotavirus vaccine. The total vaccination cost for 10 cohorts was estimated to be US$ 499.91 million. Also, US$ 470.61 million would be saved because of preventing outpatient visits and inpatient admissions (cost-saving from the society perspective). We estimated a cost per DALY averted of US$ 2868 for RV5 vaccination, which corresponds to a highly cost-effective strategy from the government perspective. In the sensitivity analysis, all scenarios tested were still cost-saving or highly cost-effective from the society perspective, except in the least favorable scenario and low vaccine efficacy and disease incidence scenario. CONCLUSION: Based on the findings, introduction of rotavirus vaccine is a highly cost-effective strategy from the government perspective. Introducing the vaccine to the national immunization program is an efficient use of available funds to reduce child mortality and morbidity in Iran.