Case report: occupationally related recurrent varicella (chickenpox) in a hospital nurse

Seroprevalence of varicella-zoster virus antibody and immunogenicity of live attenuated varicella vaccine in healthcare workers in Taiwan

BACKGROUND

Healthcare workers (HCWs) without evidence of immunity to varicella-zoster virus (VZV) are recommended to undergo varicella vaccination. Immunogenicity of live attenuated varicella vaccine has rarely been investigated among HCWs in Taiwan.

METHODS

Anti-VZV immunoglobulin G (IgG) titer was checked for all HCWs at Changhua Christian Hospital from 2011 to 2017. One-dose and two-dose (separated by 4-8 weeks) vaccines were administered to HCWs with equivocal and negative anti-varicella IgG results, respectively. Follow-up anti-VZV IgG was determined at least 4 weeks after completion of vaccination. Factors associated with seroconversion to varicella vaccination were analyzed.

RESULTS

Among 2406 included HCWs, the anti-VZV IgG serostatus was tested positive, equivocal and negative in 1924 (79.9%), 117 (4.9%) and 365 (15.2%), respectively. The seroprevalence had decreased from 88.0% (235/267) in 2011 to 72.2% (270/374) in 2017 (p for trend <0.05). A total of 67.8% (327/482) HCWs completed scheduled vaccination and serological follow-up. The seroconversion rates for HCWs with baseline equivocal and negative anti-VZV IgG results were 100% (80/80) and 79.4% (196/247) after one- and two-dose vaccination, respectively. In multivariate analysis, obesity (adjusted odds ratio, 0.308; 95% confidence interval [CI], 0.11-0.94, p = 0.039) was the only factor statistically significantly associated with seroconversion to vaccination.

CONCLUSION

Decreasing trends of seroprevalence of VZV were observed among HCWs from 2011 to 2017. HCWs who were obese were less likely to respond to varicella vaccination.

Clinical and molecular aspects of the live attenuated Oka varicella vaccine

VZV is a ubiquitous member of the Herpesviridae family that causes varicella (chicken pox) and herpes zoster (shingles). Both manifestations can cause great morbidity and mortality and are therefore of significant economic burden. The introduction of varicella vaccination as part of childhood immunization programs has resulted in a remarkable decline in varicella incidence, and associated hospitalizations and deaths, particularly in the USA. The vaccine preparation, vOka, is a live attenuated virus produced by serial passage of a wild-type clinical isolate termed pOka in human and guinea pig cell lines. Although vOka is clinically attenuated, it can cause mild varicella, establish latency, and reactivate to cause herpes zoster. Sequence analysis has shown that vOka differs from pOka by at least 42 loci; however, not all genomes possess the novel vOka change at all positions, creating a heterogeneous population of genetically distinct haplotypes. This, together with the extreme cell-associated nature of VZV replication in cell culture and the lack of an animal model, in which the complete VZV life cycle can be replicated, has limited studies into the molecular basis for vOka attenuation. Comparative studies of vOka with pOka replication in T cells, dorsal root ganglia, and skin indicate that attenuation likely involves multiple mutations within ORF 62 and several other genes. This article presents an overview of the clinical aspects of the vaccine and current progress on understanding the molecular mechanisms that account for the clinical phenotype of reduced virulence.

Implication of human herpesviruses in oncogenesis through immune evasion and supression

All human herpesviruses (HHVs) have been implicated in immune system evasion and suppression. Moreover, two HHV family members, i.e. EBV and KSHV, are recognised as oncogenic viruses. Our literature review summarises additional examples of possible oncogenic mechanisms that have been attributed to other HHVs. In general, HHVs affect almost every cancer-implicated branch of the immune system, namely tumour-promoting inflammation, immune evasion, and immunosuppression. Some HHVs accomplish these effects by inhibiting apoptotic pathways and by promoting proliferation. Mechanisms related to immunosupression and low grade chronic inflammation could eventually result in the initiation and progression of cancer. In this article we open a discussion on the members of Herpesviridae, their immune evasion and suppression mechanisms, and their possible role in cancer development. We conclude that discerning the mechanisms of interplay between HHV, immune system, and cancer is essential for the development of novel preventative and therapeutic approaches for cancer treatment and prophylaxis.

Systemic varicella-zoster virus infection in two critically ill patients in an intensive care unit

Varicella-zoster virus (VZV) usually causes localized zoster in adults. However, in immunocompromised patients, it can cause systemic infection accompanied by complications such as pneumonia, encephalitis, and hepatitis. Although most of critically ill patients in intensive care unit (ICU) are immunologically compromised, they are usually not considered to be at risk for systemic VZV infection.We report two cases of systemic VZV infection occurring in critically ill patients in an ICU. One patient was a 69-year-old man with Streptococcus pneumoniae-induced purpurafulminans, and the other was a 75-year-old woman with severe acute pancreatitis. During the clinical course in the ICU, characteristic vesicles with umbilical fossa appeared diffusely and bilaterally on their face, trunk, and extremities. VZV-specific IgG levels were confirmed to be elevated compared to that of the pre-onset, and a diagnosis of recurrent VZV infection was made in both patients. The patients were treated at the same ICU but did not coincide with each other; therefore a cross-infection was unlikely. They were treated with intravenous acyclovir, but the latter patient eventually died of respiratory failure.VZV infection can cause a number of serious complications, and can lead to death in some patients. Early detection and proper treatment are needed to prevent the infection from spreading out and save the patients. It might be necessary to consider antiviral prophylaxis against VZV infection for a part of critically ill patients in ICU, although the effectiveness of this approach is yet to be established.

Seroepidemiology of varicella zoster virus in healthcare workers in Babol, Northern Iran

BACKGROUND

Varicella zoster virus (VZV) infection is one of the nosocomial infections and healthcare workers (HCWs) are at high risk group who work in the hospital with likelihood of varicella acquisition or transmission. This study evaluated the VZV seroprevalence in this high risk population in Babol, Iran.

METHODS

Serological testing for VZV using enzyme linked immunosorbent assay (ELISA) was performed on 459 HCWs in Ayatollah Rouhani Hospital, Babol, Northern Iran from 2011 to 2012. A questionnaire was completed including age, gender, place of residence, marital status, history of chickenpox, educational level, working experience and risk of exposure. The data were collected and analyzed.

RESULTS

The mean age of these subjects was 32.2±1.1 years. Four hundred-sixteen (90.6%) cases were females and 43 (9.4%) were males. The overall positive seroprevalence of VZV was 94.6%. No statistically significant differences were observed between age, gender, place of residence, risk of exposure, marital status, educational level, working experience and seropositivity. The seropositivity of varicella was seen in 278 (95.5%) of 297 cases with positive history and in 30 (81.1%) of 37 cases who did not (p=0.005).

CONCLUSION

The results show that a positive history of VZV is associated with positive seroprevalence but can not be a reliable indicator of the immunity, therefore, serological screening should be considered for all the HCWs.

Study of susceptibility towards varicella by screening for the presence of IgG antibodies among nursing and medical students of a tertiary care teaching hospital in pune, India

BACKGROUND

It is believed that all suffer from chickenpox infection in their childhood. Many studies abroad and some in India clearly indicate that many individuals escape the infection in childhood, and thus, remain susceptible in adulthood. Adulthood chickenpox is a more serious infection than childhood. Prior screening of health care workers for the presence of IgG antibodies against Varicella will not only prevent hospital outbreaks but also economic and academic loss faced by the students. This will also have an important implication in terms of patient care as there is a threat of spreading Varicella to immuno-compromised patients. Definite history of prior infection of chickenpox is considered as an indicator for immunity towards the same. However, the reliability of this needs to be tested.

AIM

A study to assess the susceptibility of nursing and medical students towards Varicella infection by screening for IgG antibodies against Varicella virus and to identify any risk factors for the same.

SETTINGS AND DESIGN

A hospital-based cross-sectional study in nursing and medical students.

MATERIALS AND METHODS

Total 78 nursing and medical students participated in the study. They were given prestructured and pretested questionnaires. After obtaining informed consent, blood sample was collected and screened for the presence of IgG antibodies against Varicella by Enzyme Linked Immunosorbent Assay (ELISA) by using a commercial kit.

STATISTICAL ANALYSIS

Epi_info 2002 was used for analysis. Age of the study subjects were summarized as mean age and standard deviation. Susceptibility was analyzed as percentage with 95% confidence interval and Chi Square test was used to find association of susceptibility status with sex and region of residence in childhood. Relevance of definite history as an indicator for immunity was assessed by calculating sensitivity, specificity, positive and negative predictive values with 95% confidence interval.

RESULTS

Twenty males (25.6%) and 58 females (74.4%) participated in the study from medical and nursing students. The mean age ± standard deviation of mean was 19.4 ± 1.42 years for female students and 20.8 ± 2.13 years for male students. Total 20 (25.6%) students were found to be susceptible to Varicella with the confidence interval ranging from 15.8% to 35.4%. With respect to the gender of the students, the difference between the susceptibility percentage in female students (32%) and in male students (14.3%) was only a numerical difference and not statistically significant (χ(2) = 2.098, P=0.147, d.f. = 2). Also, the susceptibility was seen significantly more among Keralite students (Pearson Chi-Square=16.736, d.f=6, P=0.008; Likelihood Ratio=15.086, d.f=6, P=0.035; Fisher's Exact Test=13.569, p=0.022). The sensitivity of definite history of prior chickenpox infection as an indicator of immunity was only 55.17%, with C.I ranging from 43.9% to 66.4%, specificity was 80%, with C.I. ranging from 70.9% to 86%, and positive predictive value was 88.8% with C.I of 81.7% to 89% and negative predictive value of history of 66.6% with C.I. of 56% to 77.2%.

CONCLUSION

Total 20 (25.6%) students were found to be susceptible to Varicella with the confidence interval ranging from 15.8% to 35.4%. Thus, there is a need for vaccination of all susceptible individuals. Definite history of prior chickenpox infection is not a reliable indicator of immunity against the same. The investigators recommend screening for IgG antibodies against Varicella of all students selected for the M.B.B.S. (Bachelor of Medicine and Bachelor of Surgery) and nursing course, and vaccination for susceptible individuals to prevent institutional outbreak and academic loss.

Varicella reinfection in a seropositive physician following occupational exposure to localized zoster

A 32-year-old physician with a history of chickenpox at age 5 and seropositivity to varicella-zoster virus (VZV) at age 30 developed fever and vesicular rash 14 days after examining an immunocompetent patient with localized herpes zoster ophthalmicus. Vesicular viral culture grew VZV, and the physician was diagnosed with VZV reinfection.

Varicella zoster virus in health care workers in northern Israel: seroprevalence and predictive value of history of varicella infection

Health care workers (HCWs) are susceptible to hospital acquired varicella zoster virus (VZV). We evaluated seroprevalence and predictive value of a history of varicella disease (VD) with VZV serology in HCWs in northern Israel. A total of 200 HCWs were enrolled. A high rate of seropositivity for VZV-IgG was found: 98.5% seropositive and only 1.5% seronegative. A positive history of VD was an excellent predictor for the presence of VZV-IgG; however, a negative history of VD does not rule out the presence of VZV-IgG.