Israel Medical Association Journal

Background: Healthcare workers (HCWs) have close interaction with confirmed or suspected coronavirus disease 2019 (COVID-19) patients. Infection rates reported among HCWs is between 3% and 17%, and asymptomatic HCWs are a potential source of nosocomial transmission to vulnerable patients and colleagues. Universal mask use and good supply of personal protective equipment was implemented early at our institution.

Objectives: To determine the rate of infection by the serologic status of HCWs during first three COVID-19 waves, based on occupation and risk of exposure, compared to Israeli general population.

Methods: We conducted a prospective cohort study at Emek Medical Center from April 2020 to April 2021. A total of 101 HCWs volunteered to be followed at six time points by a serology test and a questionnaire.

Results: A total of 101 HCWs completed six serologic tests. All participants were seronegative at the four initial tests. The cumulative seropositivity rate for COVID-19 in HCWs was 9.9% (10/101). Only three seropositive HCWs (2.97%) were hospital-acquired.

Conclusions: Seroprevalence and seroconversion dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in 101 HCWs during COVID-19 outbreaks at Emek Medical Center were similar to the epidemiological curve of positive polymerase chain reaction results of the Israeli population, as published by the Israeli Ministry of Health, at each time point. Universal mask use and infection control measures may have contributed to a low hospital infection rate.

Background: The Epstein-Barr virus (EBV) is one of the most common viruses found in humans, causing lifelong infection in up to 95% of the world population.

Objectives: To analyze the seroprevalence of EBV infection in different population groups in Croatia.

Methods: During a 2 year period (2015–2016), a total of 2022 consecutive serum samples collected from Croatian residents were tested for the presence of EBV-specific viral capsid antigen (VCA) immunoglobulin M (IgM) and IgG antibodies using an enzyme-linked immunoassay. IgM/IgG-positive samples were further tested for IgG avidity.

Results: The overall prevalence of EBV IgG antibodies was 91.4%. Females had significantly higher IgG seroprevalence than males (93.1% vs. 89.9%, P = 0.008). According to age, IgG seropositivity increased progressively from 59.6% in children age < 9 years to 98.3% in 30–39 year olds, and remained stable thereafter (P < 0.001). The IgG seroprevalence differed significantly among groups: 68.1% in children/adolescents and 95.9% in adults; multiple sclerosis (100%), hemodialysis patients (97.7%), heart transplant recipients (93.8%), hematological malignancies (91.2%), and Crohn’s disease (88.5%), P < 0.001. IgM antibodies were detected in 9% of participants. Using IgG avidity, recent primary EBV infection was documented in 83.8% of IgM-positive subjects < 9 years old, 69.2% age 10–19, 33.3% age 20–29, and 3.6–4.2% > 40. All IgM positive participants > 40 years showed high IgG avidity. Logistic regression showed that age is associated with EBV IgG seropositivity.

Conclusions: EBV is widespread in the Croatian population. Older age appears to be the main risk factor for EBV seropositivity.

Background: Human parvovirus B19 is a global and common infectious pathogen in humans, primarily in children.

Objectives: To assess the immunoglobulin G seroprevalence of B19 in children in Israel.

Methods: Overall, 128 previously healthy children (1.5–17 years old) hospitalized for various diseases other than acute human parvovirus B19 infection were assessed for IgG[1] to the virus by enzyme-linked immunosorbent assay. 

Results: The IgG seroprevalence increased from 22% in children aged 1.5–9 years to 52% in older children (P = 0.001).

Conclusions: Our data suggest that most acute parvovirus B19 infections in Israel occur in the early school years, and that by 18 years of age 50% of Israeli children have been infected by the virus.

[1] IgG = immunoglobulin G

Background: Two recent studies found that the prevalence of cryptosporidiosis among children in Israel was 3.4-7.4%.

Objectives: To assess the cumulative infection rate by testing immunoglobulin A and G seroprevalence for Cryptosporidium in children and adults in Israel.

Patients and Methods: The seroprevalence of IgA and IgG anti-Cryptosporidium antibodies was determined by an enzyme-linked immunosorbent assay procedure in a group of 163 healthy children and adults.

Results: The overall seroprevalence rates for IgG, IgA, both IgA and IgG, and any immunoglobulin were 12.6%, 23%, 30% and 65.6% respectively. Half the children under the age of 12 years were already infected, with seroprevalence increasing to 95.6% in those over age 13 (P<0.05). Seropositivity for IgG or IgA did not significantly increase with age.

Conclusions: These results indicate that a large percentage of healthy children and adults in northern Israel have been infected with Cryptosporidium, and at early ages.

Background: There is an increasing number of reports of pertussis among older children and adults. The development and licensure of an acellular pertussis vaccine offer the possibility of adult vaccination against the disease. Information on immunity to pertussis in this age group is needed before any vaccination policy can be considered.

Objectives: To study the seroepidemiology of pertussis antibodies in a random sample of adolescents.

Methods: Serum IgG antibodies to whole-cell lysate of Bordetella pertussis were measured by enzyme-linked immunosorbent assay in sera of 533 Israeli military recruits aged 17–18 years. Epidemiologic variables were collected by a questionnaire and analyzed for correlation with pertussis antibodies.  

Results: Of the sera tested 58.6% were positive for pertussis IgG antibodies, while 35.4% were negative and 6% were borderline. The seropositivity rate was significantly higher among females and non-smokers than among males and smokers. Serum samples of subjects found negative to Bordetella pertussis on recruitment were tested again, using the same ELISA assay, 2–3 years later.  Seroconversion during the 3 year military service was detected in 12.5% of 40 subjects. Using the pertussis toxin as the antigen in a subsample of 160 sera, the seroprevalence was lower than that detected by the whole-cell lysate on the same sera (45% vs. 58%).

Conclusions: A significant part of the adolescent population in Israel has low titer of serum IgG antibodies to the multiple antigens of B. pertussis. The relatively low concentration of anti-pertussis antibodies, together with the serological evidence of exposure to the disease indicates that booster immunization with the acellular pertussis vaccine of military recruits should be considered after more information on the incidence of clinical cases of pertussis will be available.

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ELISA = enzyme-linked immunosorbent assay

Background: Previous studies have published controversial results regarding a connection between Helicobacter pylori infection and colorectal cancer. One possible mechanism is increased gastrin secretion in subjects infected with H. pylori, insofar as gastrin is known to be a trophic factor for the colonic mucosa.

Objectives: To investigate a possible role of gastrin secretion in H. pylori infection associated with colorectal cancer, and determine whether H. pylori infection is a factor in this disease.

Methods: The serum gastrin levels and the presence of H. pylori IgG antibodies were measured in 51 colorectal cancer patients and 51 control subjects. The cancer patients were also tested for carcinoembryonic antigen and CA 19-9.

Results: H. pylori IgG antibodies were found in the serum of 41 (80.4%) of the cancer patients compared to 32 (62.7%) of the control subjects (P=0.05). A significant correlation was found between CA 19-9 (γ=0.3432, n=49, P=0.01) and seropositive H. pylori IgG antibodies in the serum of the cancer patients (odds ratio 2.43, and 95% confidence limit 0.99-5.95), but none between CEA and H. pylori IgG antibodies nor between the serum gastrin level and the presence of colorectal cancer.

Conclusions: The results of this study indicate a significant association between seropositive H. pylori IgG antibodies and elevated CA 19-9 in colorectal cancer patients, but no correlation between the serum gastrin level and the presence of this cancer. H. pylori seropositivity is more prevalent in patients with colorectal cancer.