Prevalence of serological markers against measles, rubella, varicella, hepatitis B, hepatitis C, and human immunodeficiency virus among medical residents in Mexico

Hepatitis B Virus Genotype H: Epidemiological, Molecular, and Clinical Characteristics in Mexico

The hepatitis B virus (HBV), comprising of ten genotypes (A-J), has been a silent threat against humanity, constituting a public health problem worldwide. In 2016, the World Health Organization set forth an impressive initiative for the global elimination of viral hepatitis by 2030. As the target date approaches, many nations, particularly in the Latin American region, face challenges in designing and implementing their respective elimination plan. This review aimed to portray the state of knowledge about the epidemiological, molecular, and clinical characteristics of HBV genotype H (HBV/H), endemic to Mexico. PubMed, Scopus, Web of Science, and Google Scholar were searched to compile scientific literature over 50 years (1970-2022). A total of 91 articles were organized into thematic categories, addressing essential aspects such as epidemiological data, risk factors, HBV genotype distribution, HBV mixed infections, clinical characteristics, and vaccination. The prevalence and its associated 95% confidence interval (95% CI) were estimated using the Metafor package in R programming language (version 4.1.2). We provide insights into the strengths and weaknesses in diagnostics and prevention measures that explain the current epidemiological profile of HBV/H. Training, research, and awareness actions are required to control HBV infections in Mexico. These actions should contribute to creating more specific clinical practice guides according to the region's characteristics. Mexico's elimination plan for HBV will require teamwork among the government health administration, researchers, physicians, specialists, and civil society advocates to overcome this task jointly.

Seroepidemiology of hepatitis viruses, measles, mumps, rubella and varicella among healthcare workers and students: Should we screen before vaccination?

BACKGROUND

Health care workers (HCWs) and students are at increased risk for blood borne infections and vaccine preventable diseases (VPDs). The aim of this study was to determine the seroprevalence of antibodies against measles, rubella, mumps, varicella zoster virus (VZV), hepatitis A and B viruses among HCWs and students and to determine whether there are differences according to gender and age group.

METHODS

Information about characteristics of the 1053 participants, history of disease and vaccination status were collected using a structured questionnaire. Serum samples were tested for antibodies by commercial immunoenzymatic assays.

RESULTS

Seropositivity rates were 57.1% for measles, 74% for mumps, 96.3% for rubella, 93.7% for VZV, 33.9% for hepatitis A virus and 92.2% for hepatitis B virus. Susceptibility rates among participants 18-26, 27-38 and >38 years of age were statistically significant for measles (46%, 18.6% and 0%; p < 0.001) and mumps (27.1%, 12.9% and 21.4%; p < 0.05), respectively.

CONCLUSION

Low seropositivity rates for measles, mumps and HAV are important findings. For other diseases other than VZV, it is thought that vaccination without pre-screening is more appropriate. Healthcare institutions should have policies for screening and vaccination of their staff and students.

Burden of varicella in Latin America and the Caribbean: findings from a systematic literature review

Background

Varicella is typically mild and self-limiting, but can be associated with complications and even death. The limited data available on varicella in Latin America and the Caribbean (LAC) indicate substantial burden in countries where varicella vaccine is not part of publicly funded childhood national immunization programs.

Methods

A systematic literature review of published studies was complemented by “gray” literature on varicella incidence, complications, mortality, and economic consequences, in the absence and presence of universal varicella vaccination (UVV) in LAC.

Results

Seroprevalence data indicate that varicella is usually a disease of childhood in LAC. Varicella incidence rates, while unreliable in the absence of mandatory reporting, show a trend to increased incidence due to greater urbanization and population density. The introduction of UVV in national immunization programs has led to significant reductions in varicella incidence in these areas.

Conclusions

Varicella continues to pose a substantial healthcare burden in LAC. The future introduction of UVV in additional countries is predicted to provide substantial reductions in cases, with important economic benefits. For countries that have already implemented UVV, the challenge is to maintain high rates of coverage and, where relevant, consider inclusion of a second dose to reduce breakthrough cases. Given the significant proportion of the region now implementing UVV, a regional recommendation in order to prevent any potential for age-shifts in varicella infection might be considered.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-6795-0) contains supplementary material, which is available to authorized users.

Immunity Against Infectious Diseases Predictive Value of Self-Reported History of Vaccination and Disease

Objective.

To determine whether self-reported history of disease and/or vaccination is predictive of immunity against hepatitis B, varicella, rubella, mumps, and measles.

Design.

The seroprevalence of viral antibodies and the predictive value of a self-report questionnaire were determined for 616 paramedical students who matriculated into Padua Medical School (Padua, Italy) during 2003-2005.

Results.

The majority of subjects (86.9%) remembered being vaccinated against hepatitis B but had no recollection of disease. Among vaccinees, 1.5% showed markers of previous infection, 6.7% tested negative for anti-hepatitis B virus surface antigen (anti-HBsAg) antibodies, and 91.8% tested positive for anti-HBsAg. Self-reported vaccination history had a positive predictive value of 93.2% for test results positive for immunity against hepatitis B. Immunity against varicella (93.7% of subjects) and rubella (95.5%) was high, compared with immunity against mumps (79.9%) and measles (83.1%). In addition, results of tests for detection of immunity against mumps and measles were equivocal for more than 7% of subjects, probably because their vaccination regimen was not completed. Self-reported histories of varicella disease and rubella disease and vaccination had high positive predictive values (greater than 98% each) for testing positive for antiviral antibodies, compared with self-reported histories of mumps disease and vaccination and measles disease and vaccination; however, high positive predictive values were observed for self-reported histories of mumps only (92.0%) and measles only (94.7%).

Conclusions.

The self-report questionnaire used in this study did not accurately predict immunity against 5 transmittable but vaccine-preventable diseases. A complete serological evaluation of healthcare workers, followed by vaccination of those with negative or equivocal results of serological tests, is an appropriate measure to decrease the risk of infection in this population.

A global perspective of vaccination of healthcare personnel against measles: systematic review

Measles transmission has been well documented in healthcare facilities. Healthcare personnel who are unvaccinated and who lack other evidence of measles immunity put themselves and their patients at risk for measles. We conducted a systematic literature review of measles vaccination policies and their implementation in healthcare personnel, measles seroprevalence among healthcare personnel, measles transmission and disease burden in healthcare settings, and impact/costs incurred by healthcare facilities for healthcare-associated measles transmission. Five database searches yielded 135 relevant articles; 47 additional articles were found through cross-referencing. The risk of acquiring measles is estimated to be 2 to 19 times higher for susceptible healthcare personnel than for the general population. Fifty-three articles published worldwide during 1989-2013 reported measles transmission from patients to healthcare personnel; many of the healthcare personnel were unvaccinated or had unknown vaccination status. Eighteen articles published worldwide during 1982-2013 described examples of transmission from healthcare personnel to patients or to other healthcare personnel. Half of European countries have no measles vaccine policies for healthcare personnel. There is no global policy recommendation for the vaccination of healthcare personnel against measles. Even in countries such as the United States or Finland that have national policies, the recommendations are not uniformly implemented in healthcare facilities. Measles serosusceptibility in healthcare personnel varied widely across studies (median 6.5%, range 0-46%) but was consistently higher among younger healthcare personnel. Deficiencies in documentation of two doses of measles vaccination or other evidence of immunity among healthcare personnel presents challenges in responding to measles exposures in healthcare settings. Evaluating and containing exposures and outbreaks in healthcare settings can be disruptive and costly. Establishing policies for measles vaccination for healthcare personnel is an important strategy towards achieving measles elimination and should be a high priority for global policy setting groups, governments, and hospitals.

Evidence of vaccine protection among thai medical students and implications for occupational health

In a cross-sectional study of Thai medical students, we compared the seroprevalence of antibody to measles virus, rubella virus, varicella zoster virus, hepatitis A virus, and hepatitis B virus with self-reports of prior infection or vaccination. Self-report predicted immunity to varicella zoster virus only. These data contribute to risk assessment and occupational health strategies in this resource-limited setting.

Vaccination and screening of medical students: results of a student health initiative

OBJECTIVE

To evaluate the immune status and vaccination needs of first-year medical students in relation to bloodborne viruses and common vaccine-preventable diseases.

DESIGN, SETTING AND PARTICIPANTS

Survey of first-year medical students at the University of New South Wales, Sydney, NSW, attending a mandatory screening and vaccination clinic, 2002-2005.

MAIN OUTCOME MEASURES

Self-reported history of vaccination or natural infection; serological evidence of immunity to measles, mumps, rubella and varicella (presence of specific IgG) and hepatitis B (presence of hepatitis B virus surface antibodies) or infection with hepatitis B and C viruses and HIV; and Mantoux test results.

RESULTS

733 students attended the clinic (85% of those enrolled). Four students were positive for HBsAg and four had hepatitis C antibodies. None were HIV-positive. Twenty-nine per cent (216/733) were not immune to hepatitis B, 33% (238/724) to mumps, 26% (190/724) to measles, 13% (91/724) to rubella and 10% (75/724) to varicella. About 23% (91/237) needed further testing for tuberculosis. Immunity corresponded poorly with self-reported history of vaccination. More students reported vaccination against rubella (96%), measles (81%) and mumps (80%) than were immune, and fewer reported vaccination against hepatitis B (44%).

CONCLUSIONS

Many students were not immune to vaccine-preventable diseases, and a small number had a previously undiagnosed bloodborne virus infection (hepatitis B or C). The level of immunity to vaccine-preventable infections was unacceptable and justified the provision of an easily accessible program for screening and vaccination.

A low steady HBsAg seroprevalence is associated with a low incidence of HBV-related liver cirrhosis and hepatocellular carcinoma in Mexico: a systematic review

To address the relationship between hepatitis B virus (HBV) endemicity and HBV-related liver diseases in Mexico. Research literature reporting on HBsAg and antibody to hepatitis B core antigen (anti-HBc) prevalence in Mexican study groups were searched in NLM Gateway, PubMed, IMBIOMED, and others. Weighted mean prevalence (WMP) was calculated from the results of each study group. A total of 50 studies were analyzed. Three nationwide surveys revealed an HBsAg seroprevalence of less than 0.3%. Horizontal transmission of HBV infection occurred mainly by sexual activity and exposure to both contaminated surgical equipment and body fluids. High-risk groups exposed to these factors included healthcare workers, pregnant women, female sex workers, hemodialysis patients, and emergency department attendees with an HBsAg WMP ranging from 1.05% (95% confidence interval [CI], 0.68-1.43) to 14.3% (95% CI, 9.5-19.1). A higher prevalence of anti-HBc in adults than those younger than 20 years was associated with the main risk factors. Anti-HBc WMP ranged from 3.13% (95% CI, 3.01-3.24) in blood donors to 27.7% (95% CI, 21.6-33.9) in hemodialysis patients. A heterogeneous distribution of HBV infection was detected, mainly in native Mexican groups with a high anti-HBc WMP of 42.0% (95% CI, 39.5-44.3) but with a low HBsAg WMP of 2.9% (95% CI 2.08-3.75). Estimations of the Mexican population growth rate and main risk factors suggest that HBsAg seroprevalence has remained steady since 1974. A low HBsAg prevalence is related to the low incidence of HBV-related liver cirrhosis and hepatocellular carcinoma (HCC) previously reported in Mexico.

High seroprevalence of varicella, measles, mumps, rubella and pertussis antibodies in first-grade medical students

OBJECTIVE

The aim of the study was to investigate seropositivity for five vaccine-preventable communicable diseases - varicella, measles, mumps, rubella and pertussis - in a sample of first-grade medical students.

METHODS

A total of 256 students were tested for varicella IgG antibodies. In addition, 138 of the students were serologically screened for measles, mumps, rubella and pertussis antibodies. Data on vaccination and history of measles, mumps, rubella and pertussis were collected.

RESULTS

Immunity to varicella, measles, mumps and rubella was established in 97.6%, 96.4%, 97.8% and 99.3% participants, respectively. Anti-pertussis toxin antibodies were detected in 81.2% of the students.

CONCLUSIONS

The rates of varicella, measles, mumps and rubella immunity in first-grade medical students are very high. To identify those students who need vaccination before commencing practical work in healthcare facilities, a meticulous disease and vaccination history should be taken and medical records should be reviewed. Medical students providing no written evidence of adequate vaccination status should be serologically tested and vaccinated if necessary.

Prevalence of hepatitis C virus in the Mexican population: a systematic review

BACKGROUND

Although hepatitis C virus (HCV) infection is considered a relevant public health problem in Mexico, the prevalence is still under discussion. The objective of this study was to conduct a systematic review to explore the prevalence of HCV infection in the Mexican population.

METHODS

A systematic review of studies reporting prevalence in Mexican population was performed using several free-access databases.

RESULTS

Sixty-eight works fulfilled the search criteria. From these, 44 studies involved asymptomatic subjects and 28 involved patients or high-risk subjects. Prevalence of blood donors (6,955,558 persons) ranged from 0.0% to 2.05%, with 7/32 studies reporting values >1%, whereas prevalence of non-donor asymptomatic subjects (28,528 persons) from 0.0% to 2.7%, with 7/11 studies reporting values >1%, and medical personnel from 0.0% to 2.08% (1,227 persons), with 4/11 studies reporting values >1%. Prevalence of patients with chronic hepatic disease ranged from 6.7% to 77%. The most prevalent genotype was 1 (30.0-87.5%), of which subtype 1b is the most frequent (11.9-61.9%). The main risk factors were blood transfusion and unprotected sex or having multiple sex partners.

CONCLUSIONS

The prevalence in the Mexican population seems to be in accordance with that previously estimated by the World Health Organization (1-2.5%).

Diphtheria, tetanus, and varicella immunity in health care workers in neonatal units

BACKGROUND

Susceptible health care workers are at risk of acquiring and transmitting vaccine-preventable diseases to or from patients. The objective of this study was to assess antibody levels against diphtheria, tetanus, and varicella in healthcare workers.

METHODS

Antibody levels against diphtheria, tetanus, and varicella were measured in health care professionals in 2 neonatal units at the Federal University of São Paulo, Brazil.

RESULTS

Between September and November 2002, 215 of 222 (96.8%) health care workers were studied. Of those, 122 (56.7%) gave oral information regarding their vaccination status against diphtheria and tetanus and only 9 (4.2%) had their vaccination cards. Geometric mean antibody levels against diphtheria, tetanus, and varicella were 0.89 IU/mL (95%CI, 0.73 to 1.08), 0.86 IU/mL (95%CI, 0.68 to 1.07) and 1.10 IU/mL (95%CI, 0.98 to 1.24), respectively. Using internationally accepted definitions, 200 (93.0%) and 182 (84.7%) individuals had full protection against diphtheria and tetanus, respectively. Regarding varicella, 213 (99.1%) individuals were immune and 2 (0.9%) had equivocal immunity against varicella. Of 65 (30.2%) individuals without previous history of the illness, 63 (96.9%) were immune against varicella zoster virus.

CONCLUSIONS

Based on serologic screening, most professionals were immune to diphtheria, tetanus, and varicella. Absence of previous history of varicella was an unreliable identifier of susceptibility to varicella zoster virus in the health care workers studied.

Low prevalence of anti-hepatitis C virus antibodies in Mexico: A systematic review

BACKGROUND

The prevalence of reactive tests to anti-hepatitis C virus (HCV) antibodies in Mexico is unknown, though estimated to be 1%. There is no single nation-wide study or comprehensive literature review addressing the epidemiology of HCV infection in Mexico.

METHODS

We did a systematic review of English- and Spanish-language literature reporting on the frequency of anti-HCV antibodies in asymptomatic persons at low risk, of studies performed in Mexico. An exhaustive search in MEDLINE, IMBIOMED, MedicLatina, ARTEMISA and MEDIGRAPHIC databases was undertaken. Weighted mean prevalence (WMP) was calculated after combining the results of each study.

RESULTS

22 studies involving 825,377 persons at low risk, mainly blood donors, were identified. Crude seroprevalence reported in each study ranged from 0.1 to 2%, with 16 (73%) studies reporting below 1%. Overall, WMP of anti-HCV antibodies (tested by enzyme immunoassay) was 0.37% (95% CI, 0.36-0.38%), differing by country region and immunoassay generation (p < 0.01). The most frequent risk factor reported was blood transfusion. Confirmation of specific anti-HCV antibodies by recombinant immunoblot assay ranged from 30 to 100%, whereas confirmation of viremia by PCR ranged from 16 to 80%. In 3 studies on HCV genotype frequency, genotype 1 had crude prevalence ranging from 63 to 70%, subtype 1b being the most prevalent (21-47%).

CONCLUSIONS

The prevalence of anti-HCV antibodies in Mexico might be lower than previously estimated. Transfusion of blood products is the main risk factor. HCV subtype 1b is the most prevalent among persons with confirmed viremia. Information of a nation-wide survey is mandatory.

Exposure of Ugandan health personnel to measles and rubella: Evidence of the need for health worker vaccination

With rubella and, until recently, measles highly endemic in Uganda, health personnel are at risk of these vaccine-preventable diseases and a source of transmission to patients. Measles and rubella serology (IgG) and history of exposure and vaccination were determined among 311 health care workers in a nationwide study. All tested positive for measles IgG, whereas 49.2% reported having been vaccinated. Rubella antibodies were present in 98.1% of personnel; 3.2% of women of child-bearing age were still susceptible. Increasing age and longer duration of service increased the risk of rubella infection. A national policy on health worker protection should include immunisation against vaccine-preventable diseases upon entry to training.

Hepatitis B infection among health workers in Uganda: evidence of the need for health worker protection

Hepatitis B exposure was assessed in 311 health workers in Uganda, a highly endemic country. Health workers were selected by random sampling from a categorized list of health workers at district level, proportionate to the population of each district. Whereas 60.1% of health workers have evidence of hepatitis B infection, with 8.7% being chronic carriers and one (0.3%) acutely infected, 36.3% are still susceptible and could benefit from vaccination. Only 5.1% reported having had at least one dose of hepatitis B vaccine and 3.5% were apparently immune through vaccination. Needle stick injuries reported by 77% of health workers were the most common mode of exposure to blood and body fluids. Trends suggested duration of service as a predictor while age and history of blood transfusion remained significant independent risk factors for hepatitis B infection. 98% of health workers are willing to be vaccinated. These results confirm the need for protection and vaccination of health workers in Uganda against hepatitis B.

Seroprevalence and immunization history of selected vaccine preventable diseases in medical students

To evaluate protection against vaccine-preventable diseases in medical students, we obtained data on immunization status and history of diphtheria, tetanus, pertussis, poliomyelitis, measles, mumps, rubella, varicella and hepatitis B from students with elective periods in our institution. Further, serum antibodies against measles, mumps, rubella and varicella-zoster virus (VZV) and hepatitis B surface (HBs) antigen were determined on a voluntary basis. For students with incomplete immunization status or lack of protective antibodies, vaccination was offered for free. Success of catch-up immunizations was serologically confirmed 4 weeks later. From May 1999 to April 2003, 170 students were enrolled; their mean age was 26 years with a median of 25 years (range 22-48 years). Immunization records were complete in 148 (87%), incomplete in 11 (6.5%) and missing in 11 (6.5%) students. Only 26% of the cohort had a complete and up-to-date immunization status. Seroprevalence of IgG antibodies against measles, mumps, rubella, VZV and HBs (> or = 10 IU/l) in 149 students were 85, 85, 92, 97 and 90%, respectively. Indications for > or = 1 catch-up immunization were found in 125 (74%) students and were accepted by 97 of them (78%). Sixty two (99%) of 63 immunized students available for follow-up demonstrated an adequate serological response. In conclusion, the great majority of medical students had immunization gaps. Systematic immunization programmes for medical students should be implemented.