Pathogen transmission modes determine contact network structure, altering other pathogen characteristics.

Pathogen traits can vary greatly and heavily impact the ability of a pathogen to persist in a population. Although this variation is fundamental to disease ecology, little is known about the evolutionary pressures that drive these differences, particularly where they interact with host behaviour. We hypothesized that host behaviours relevant to different transmission routes give rise to differences in contact network structure, constraining the space over which pathogen traits can evolve to maximize fitness. Our analysis of 232 contact networks across mammals, birds, reptiles, amphibians, arthropods, fish and molluscs found that contact network topology varies by contact type, most notably in networks that are representative of fluid-exchange transmission. Using infectious disease model simulations, we showed that these differences in network structure suggest pathogens transmitted through fluid-exchange contact types will need traits associated with high transmissibility to successfully proliferate, compared to pathogens that transmit through other types of contact. These findings were supported through a review of known traits of pathogens that transmit in humans. Our work demonstrates that contact network structure may drive the evolution of compensatory pathogen traits according to transmission strategy, providing essential context for understanding pathogen evolution and ecology.

Hepatitis A Outbreaks in Developed Countries: Detection, Control, and Prevention.

The incidence of hepatitis A virus (HAV) infection has been low in developed countries for decades; however, many adults in these countries are susceptible to HAV infection. In recent years, the global trade of food products originating from HAV-endemic countries resulted in HAV outbreaks associated with imported foods in developed countries. This article aims to review the characteristics of selected HAV outbreaks associated with imported food in developed countries during 2012-2018, and discusses improvements in global public health capabilities and new tools for effective detection, control, and prevention of HAV outbreaks.

Hepatitis B and C virus infections transmitted through organ transplantation investigated by CDC, United States, 2014-2017.

We evaluated clinical outcomes among organ recipients with donor-derived hepatitis B virus (HBV) or hepatitis C virus (HCV) infections investigated by CDC from 2014 to 2017 in the United States. We characterized new HBV infections in organ recipients if donors tested negative for total anti-HBc, HBsAg and HBV DNA, and new recipient HCV infections if donors tested negative for anti-HCV and HCV RNA. Donor risk behaviors were abstracted from next-of-kin interviews and medical records. During 2014-2017, seven new recipient HBV infections associated with seven donors were identified; six (86%) recipients survived. At last follow-up, all survivors had functioning grafts and five (83%) had started antiviral therapy. Twenty new recipient HCV infections associated with nine donors were identified; 19 (95%) recipients survived. At last follow-up, 18 (95%) survivors had functioning grafts and 14 (74%) had started antiviral treatment. Combining donor next-of kin interviews and medical records, 11/16 (69%) donors had evidence of injection drug use and all met Public Health Service increased risk donor (IRD) criteria. IRD designation led to early diagnosis of recipient infection, and prompt implementation of therapy, likely reducing the risk of graft failure, liver disease, and death.

Characteristics of Deceased Solid Organ Donors and Screening Results for Hepatitis B, C, and Human Immunodeficiency Viruses - United States, 2010-2017.

The ongoing U.S. opioid crisis has resulted in an increase in drug overdose deaths and acute hepatitis C virus (HCV) infections, with young persons (who might be eligible organ donors) most affected.*,† In 2013, the Public Health Service released a revised guideline to reduce the risk for unintended organ transplantation-associated hepatitis B virus (HBV), HCV, and human immunodeficiency virus (HIV) transmission (1). The guideline describes criteria to categorize donors at increased risk (increased risk donors [IRDs]) for transmitting these viruses to recipients (1). It also recommends universal donor testing for HBV, HCV, and HIV.§ CDC analyzed deceased donor data for the period 2010-2017 reported to the Organ Procurement and Transplantation Network for IRDs and standard risk donors (SRDs) (i.e., donors who do not meet any of the criteria for increased risk designation). During this period, the proportion of IRDs increased approximately 200%, from 8.9% to 26.3%; the percentage with drug intoxication reported as the mechanism of death also increased approximately 200%, from 4.3% to 13.4%; and the proportion of these donors with reported injection drug use (IDU) increased approximately 500%, from 1.3% to 8.0%. Compared with SRDs, IRDs were significantly more likely to have positive HBV and HCV screening results. These findings demonstrate the continuing need for identifying viral bloodborne pathogen infection risk factors among deceased donors to reduce the risk for transmission, monitor posttransplant infection in recipients, and offer treatment if infection occurs.

Using Population Based Hospitalization Data to Monitor Increases in Conditions Causing Morbidity Among Persons Who Inject Drugs.

Epidemics of opioid use and injection drug use (IDU) are associated with an increase in HIV and viral hepatitis infections and overdose deaths in the United States. Persons who inject drugs (PWID) are also at risk for serious infections caused by skin organisms introduced via IDU. We examined National Inpatient Sample hospital discharge data to determine trends in three serious infectious disease-associated conditions that primarily affect PWID in addition to HIV and viral hepatitis: infective endocarditis (IE), central nervous system (CNS) abscesses, and osteomyelitis. We found an increase in the number of primary hospitalization discharge diagnoses for IE among persons aged ≤39 years from 2009 to 2013. Hospitalization rates for these diagnoses also increased over this study period for person with secondary diagnoses of hepatitis B, C, or D viruses and substance-related disorders for IE, CNS abscess and osteomyelitis. Policies that improve access to sterile injection equipment, improve education regarding IDU, and treatment for substance use disorder may help to reduce the impact of serious and often fatal infectious diseases among PWID.

Assessing Disparities in the Rates of HCV Diagnoses Within American Indian or Alaska Native Populations Served by the U.S. Indian Health Service, 2005-2015.

Hepatitis C virus (HCV) disproportionately affects American Indians/Alaska Natives (AI/AN). The Indian Health Service (IHS), via federal and tribal health facilities provides medical services to an estimated 2.2 million AI/AN people in the United States. HCV diagnoses, defined by International Classification of Diseases 9th Revision, Clinical Modification (ICD-9-CM) codes, were analyzed from 2005 to 2015. Results showed 29,803 patients with an HCV diagnosis; 53.4% were among persons born 1945-1965 and overall HCV burden was higher among males than females. These data will help inform local, regional, and national efforts to address, plan for and carry out a national strategy to provide treatment for HCV infected patients and programs to prevent new HCV infections.

Hepatitis B Surface Antigen Screening Among Pregnant Women and Care of Infants of Hepatitis B Surface Antigen-Positive Mothers - Guam, 2014.

Hepatitis B virus (HBV) infection is endemic among adults in the U.S. territory of Guam (1,2). Perinatal HBV transmission, which occurs at birth from an infected mother to her newborn infant, is a major mode of HBV transmission and maintains HBV endemicity (3). Approximately 90% of HBV-infected infants will develop chronic HBV infection, and approximately 25% of those will die prematurely from liver failure or hepatocellular carcinoma (4,5). Since 1988, the Advisory Committee on Immunization Practices has recommended that all pregnant women be screened for hepatitis B surface antigen (HBsAg), an indicator of HBV infection, and that infants of women who screen positive (HBsAg-positive women) receive postexposure prophylaxis (PEP) (hepatitis B vaccine and hepatitis B immunoglobulin [HBIG]). When received within 12 hours of birth, PEP is 85%-95% effective in preventing perinatal HBV transmission (5,6). Hepatitis B vaccine provides long-term active immunity to HBV infection and HBIG provides short-term passive immunity to HBV infection until the infant responds to the vaccine (5). Hepatitis B vaccine was introduced into the routine universal infant vaccination schedule in Guam in 1988 (1).

Comparison of Three Popular Methods for Recruiting Young Persons Who Inject Drugs for Interventional Studies.

Persons who inject drugs (PWID) are at risk for adverse health outcomes as a result of their drug use, and the resulting social stigma makes this a difficult population to reach for interventions aimed at reducing morbidity and mortality. During our study of adult PWID aged ≤40 years living in San Diego during 2009 and 2010, we compared three different sampling methods: respondent-driven sampling (RDS), venue-based sampling at one syringe exchange program (SEP), and street-based outreach. We compared demographic, socioeconomic, health, and behavioral factors and tested participants for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) and compared across the three methods. Overall, 561 (74.8%) of the targeted 750 PWID were enrolled. Venue-based convenience sampling enrolled 96% (242/250) of the targeted participants, followed closely by street-based outreach with 92% (232/250) recruited. While RDS yielded the fewest recruits, producing only 35% (87/250) of the expected participants, those recruited through RDS were more likely to be female, more racially diverse, and younger.

Hepatitis A hospitalizations in the United States, 2002-2011.

UNLABELLED: Hepatitis A illness severity increases with age. One indicator of hepatitis A illness severity is whether persons are hospitalized. We describe changes in primary hepatitis A hospitalization rates in the United States from 2002-2011, including changes in demographics, secondary discharge diagnoses, and factors affecting hospitalization duration. We describe changes from 2002-2011 among U.S. residents hospitalized with a principal hepatitis A diagnosis and accompanying secondary diagnoses using ICD-9 codes from the National Inpatient Survey discharge data. We calculated rates of hospitalizations with hepatitis A as the principal discharge diagnosis and rates of secondary discharge diagnoses. Using multiple regression, we assessed the effect of secondary diagnoses on hospitalization length of stay for five time intervals: 2002-2003, 2004-2005, 2006-2007, 2008-2009, and 2010-2011. Rates of hospitalization for hepatitis A as a principal diagnosis decreased from 0.72/100,000 to 0.29/100,000 (P < 0.0001) and mean age of those hospitalized increased from 37.6 years to 45.5 years (P < 0.0001) during 2002-2011. The percentage of hepatitis A hospitalizations covered by Medicare increased from 12.4% to 22.7% (P < 0.0001). Secondary comorbid discharge diagnoses increased, including liver disease, hypertension, ischemic heart disease, disorders of lipid metabolism, and chronic kidney disease. No changes in length-of-stay or in-hospital deaths from hepatitis A over time were found, but persons with liver disease were hospitalized longer. CONCLUSION: Hospitalization rates for hepatitis A illness have declined significantly from 2002-2011, but the characteristics of the hospitalized population also changed. Persons hospitalized for hepatitis A in recent years are older and more likely to have liver diseases and other comorbid medical conditions. Hepatitis A disease and resulting hospitalizations could be prevented through adult vaccination.

Notes from the Field: Hepatitis C Outbreak in a Dialysis Clinic--Tennessee, 2014.

Outbreaks of hepatitis C virus (HCV) infections can occur among hemodialysis patients when recommended infection control practices are not followed (1). On January 30, 2014, a dialysis clinic in Tennessee identified acute HCV in a patient (patient A) during routine screening and reported it to the Tennessee Department of Health. Patient A had enrolled in the dialysis clinic in March 2010 and had annually tested negative for HCV (including a last HCV test on December 19, 2012), until testing positive for HCV antibodies (anti-HCV) on December 18, 2013 (confirmed by a positive HCV nucleic acid amplification test). Patient A reported no behavioral risk factors, but did have multiple health care exposures.

Awareness of HCV infection among persons who inject drugs in San Diego, California.

We asked persons who inject drugs questions about HCV, including past testing and diagnosis followed by HCV testing. Of 540 participants, 145 (27%) were anti-HCV positive, but of those who were positive, only 46 (32%) knew about their infection. Asking about previous HCV testing results yielded better results than did asking about prior HCV diagnosis. Factors associated with knowing about HCV infection included older age, HIV testing, and drug treatment. Comprehensive approaches to educating and screening this population for HCV need implementation.

Hepatitis E virus among persons who inject drugs, San Diego, California, USA, 2009-2010.

Data about prevalence of hepatitis E virus infection in persons who inject drugs are limited. Among 18-40-year-old persons who inject drugs in California, USA, prevalence of antibodies against hepatitis E virus was 2.7%. This prevalence was associated with age but not with homelessness, incarceration, or high-risk sexual behavior.

Outbreak of hepatitis B and hepatitis C virus infections associated with a cardiology clinic, West Virginia, 2012-2014.

OBJECTIVE: To stop transmission of hepatitis B virus (HBV) and hepatitis C virus (HCV) infections in association with myocardial perfusion imaging (MPI) at a cardiology clinic. DESIGN: Outbreak investigation and quasispecies analysis of HCV hypervariable region 1 genome. SETTING: Outpatient cardiology clinic. PATIENTS: Patients undergoing MPI. METHODS: Case patients met definitions for HBV or HCV infection. Cases were identified through surveillance registry cross-matching against clinic records and serological screening. Observations of clinic practices were performed. RESULTS: During 2012-2014, 7 cases of HCV and 4 cases of HBV occurred in 4 distinct clusters among patients at a cardiology clinic. Among 3 case patients with HCV infection who had MPI on June 25, 2014, 2 had 98.48% genetic identity of HCV RNA. Among 4 case patients with HCV infection who had MPI on March 13, 2014, 3 had 96.96%-99.24% molecular identity of HCV RNA. Also, 2 clusters of 2 patients each with HBV infection had MPI on March 7, 2012, and December 4, 2014. Clinic staff reused saline vials for >1 patient. No infection control breaches were identified at the compounding pharmacy that supplied the clinic. Patients seen in clinic through March 27, 2015, were encouraged to seek testing for HBV, HCV, and human immunodeficiency virus. The clinic switched to all single-dose medications and single-use intravenous flushes on March 27, 2015, and no further cases were identified. CONCLUSIONS: This prolonged healthcare-associated outbreak of HBV and HCV was most likely related to breaches in injection safety. Providers should follow injection safety guidelines in all practice settings.

Prenatal Screening for and Prevalence of Hepatitis B Surface Antigen in Pregnant Women and Prevention of Transmission to Infants Born to Infected Mothers-Guam, 2014.

BACKGROUND: Perinatal transmission is the major mode of hepatitis B virus (HBV) transmission and drives HBV endemicity in the US territory of Guam. We assessed correlates of prenatal hepatitis B surface antigen (HBsAg) screening and HBsAg positivity among pregnant women and evaluated the care of infants of HBsAg-positive women. METHODS: Demographic and clinical data were abstracted from the maternal medical records of 966 randomly selected live infants born in 2014. Frequencies were calculated, and prevalence ratios (PRs) and 95% confidence intervals (CIs) were estimated using Poisson regression. RESULTS: Among the mothers of the 966 infants, 78.2% were Pacific Islanders, 56.9% were >25 years old (born before universal infant hepatitis B vaccination in Guam), 89.0% received prenatal care (PNC), 96.7% underwent prenatal HBsAg screening, and 2.0% were HBsAg positive. Approximately 15% of the women who did not have PNC were not screened for HBsAg. Receipt of PNC was associated with HBsAg screening (adjusted PR, 1.13 [95% CI, 1.04-1.23]), and HBsAg positivity was associated with a maternal age of >25 years (adjusted PR, 6.80 [95% CI, 1.32-35.08]). All 18 infants of the HBsAg-positive mothers received hepatitis B vaccine, and 17 (94.4%) received hepatitis B immunoglobulin. CONCLUSION: Although the prenatal HBsAg screening prevalence in this sample was high, the maternal HBsAg prevalence among women in this sample was more than 14 times and 2 times the prevalence among US-born Pacific Islander/Asian women and all women in the continental United States, respectively. Improving access to PNC, ensuring that all pregnant women in Guam (especially those born before universal hepatitis B vaccination) are screened for HBsAg, and adopting postexposure prophylaxis for infants of HBsAg-positive mothers as standard clinical practice are important for preventing perinatal HBV transmission and reducing HBV endemicity.

The Predictive Value of International Classification of Disease Codes for Chronic Hepatitis C Virus Infection Surveillance: The Utility and Limitations of Electronic Health Records.

Surveillance of chronic hepatitis C virus (HCV) cases faces limitations that result in delays and under-reporting. With increasing use of electronic health records (EHRs), the authors evaluated the predictive value of using International Classification of Diseases, Ninth Revision (ICD-9) codes to identify chronic HCV cases from EHR data. Longitudinal EHR data from 4 health care systems during 2006-2012 were evaluated. Using chart abstraction and review to confirm chronic HCV cases ("gold standard" definition), the authors calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 2 case definitions: (1) ≥2 ICD-9 codes separated by ≥6 months and (2) ≥1 positive HCV RNA (ribonucleic acid) test. Among 2,718,995 patients, 20,779 (0.8%) with ICD-9 codes indicating a likely diagnosis of chronic HCV infection were identified; 13,595 (65.4%) of these were randomly selected for review. Case definition 1 (≥2 ICD-9 codes separated by ≥6 months) had 70.3% sensitivity, 91.9% PPV, 99.9% specificity, and 99.9% NPV while case definition 2 (≥1 positive HCV RNA test) had 74.1% sensitivity, 97.4% PPV, 99.9% specificity, and 99.9% NPV. The predictive values of these alternate EHR-derived ICD-9 code-based case definitions suggest that these measures may be useful in capturing the burden of diagnosed chronic HCV infections. Their use can augment current chronic HCV case surveillance efforts; however, their accuracy may vary by length of observation and completeness of EHR data.

The Financial Burden of Public Health Responses to Hepatitis A Cases Among Food Handlers, 2012-2014.

When food handlers become ill with hepatitis A virus (HAV) infection, state and local health departments must assess the risk of HAV transmission through prepared food and recommend or provide postexposure prophylaxis (PEP) for those at risk for HAV infection. Providing PEP (eg, hepatitis A [HepA] vaccine or immunoglobulin), however, is costly. To describe the burden of these responses on state and local health departments, we determined the number of public health responses to HAV infections among food handlers by reviewing public internet sources of media articles. We then contacted each health department to collect data on whether PEP was recommended to food handlers or restaurant patrons, the number of PEP doses given, the number of HepA vaccine or immunoglobulin doses given as PEP, and the mean number of health department person-hours required for the response. Of 32 public health responses identified from Twitter, HealthMap, and Google alerts from January 1, 2012, to December 31, 2014, a total of 27 (84%) recommended PEP for other food handlers or restaurant patrons or both. Per public health response, the mean cost per dose of the HepA vaccine or immunoglobulin was $34 139; the mean personnel cost per response was $7329; and the total mean cost of each response was $41 468. PEP is expensive. Less aggressive approaches to PEP, such as limiting PEP to fellow food handlers in nonoutbreak situations, should be considered in the postvaccination era. HepA vaccine for PEP provides long-term immunity and can be used when immunoglobulin is unavailable or cannot be administered within 14 days of exposure to HAV.

Hepatitis C virus transmission in a skilled nursing facility, North Dakota, 2013.

BACKGROUND: From March-May 2013, 3 cases of acute hepatitis C virus (HCV) infection were diagnosed among elderly patients residing at the same skilled nursing facility (facility A) and who received health care at hospital X during their likely exposure period. METHODS: We performed HCV testing of at-risk populations; quasispecies analysis was performed to determine relatedness of HCV in persons with current infection. Infection control practice assessments were conducted at facility A and hospital X. Persons residing in facility A on September 9, 2013, were enrolled in a case-control study to identify risk factors for HCV infection. RESULTS: Forty-five outbreak-associated infections were identified. Thirty cases and 62 controls were enrolled in the case-control study. Only podiatry (odds ratio, 11.6; 95% confidence interval, 2.4-57.2) and international normalized ratio monitoring by phlebotomy (odds ratio, 6.7; 95% confidence interval, 1.7-26.6) at facility A were significantly associated with case status. Infection control lapses during podiatry and point-of-care testing procedures at facility A were identified. CONCLUSIONS: HCV transmission was confirmed among residents of facility A. The exact mode of transmission was not able to be identified, but infection control lapses were likely responsible. This outbreak highlights the importance of prompt reporting and investigation of incident HCV infection and the need for adherence to basic infection control procedures by health care personnel.

Hepatitis A Infections Among Food Handlers in the United States, 1993-2011.

We reviewed news reports of hepatitis A virus (HAV)-infected food handlers in the United States from 1993 to 2011 using the LexisNexis® search engine. Using U.S. news reports, we identified 192 HAV-infected food handlers who worked while infectious; of these HAV-infected individuals, 34 (18%) transmitted HAV to restaurant patrons. News reports of HAV-infected food handlers declined from 1993 to 2011. This analysis suggests that universal childhood vaccination contributed to the decrease in reports of HAV-infected food handlers, but mandatory vaccination of this group is unlikely to be cost-effective.

Hepatitis A and B among young persons who inject drugs--vaccination, past, and present infection.

BACKGROUND: Our study aims were to assess hepatitis A virus (HAV) and hepatitis B virus (HBV) susceptibility and infection among young persons who inject drugs (PWID) who may have been vaccinated as children and to evaluate self-report of HAV and HBV vaccination. METHODS: We recruited PWID aged 18-40 years-old in San Diego during 2009 and 2010 and collected demographic, socioeconomic, health, and behavioral factors. Participants were asked if they had been vaccinated against HAV and HBV, and serum samples were collected for HAV and HBV serologic testing. RESULTS: Of 519 participants, 365 (72%) were male, 252 (49%) were white non-Hispanic, 38 (7%) were Black non-Hispanic, 138 (27%) were White Hispanic, and 22 (4%) were born outside the U. S. Of the total participants, 245 (47%) had surface hepatitis B antibody (anti-HBs) titers <10mIU/ml (i.e., HBV susceptible) and 325 (63%) had no detectable HAV antibodies (HAV susceptible). Hepatitis B surface antigen was detected in 7 (1%) of total participants; and 135 (26%) were anti-HCV-antibody positive. Compared to serologic findings, self-report of HBV and HAV vaccination was 71% and 41% sensitive, and 58% and 73% specific, respectively. CONCLUSION: HAV and HBV antibodies in half or more of this young PWID population did not have levels indicative of protection, and about a quarter had HCV infection, putting them at risk for complications resulting from co-infection with HAV or HBV. Programs serving this population should vaccinate PWIDs against HAV and HBV and not rely on self-report of vaccination.