Screening family and sexual contacts of HBsAg+ persons in the Pilsen region

THE AIM OF THE STUDY

To detect HBsAg-positive persons and to offer their family and sexual contacts, after screening for viral hepatitis B (VHB) markers, free vaccination against the infection.

MATERIAL AND METHODS

In collaboration with laboratories, all persons with confirmed HBsAg in the Pilsen Region (549,618 population) were prospectively detected. From these persons, the following data were collected: reason for examination, clinical diagnosis, and ethnicity/nationality. Their family and sexual contacts were screened for serologic markers (HBsAg, anti-HBc, anti-HBs) and vaccinated.

RESULTS

Between 1997-2005, 1,053 HBsAg+ persons were routinely detected by the laboratories in the Pilsen Region. The average age of the infected persons was 41.7 years (range 0-90 years). At the time of the detection, 63.4% of the HBsAg positives were clinically "healthy" carriers. Within the monitored period there was a considerable increase in the HBsAg positivity rate among immigrants (particularly from Vietnam). Of 908 family and sexual contacts, 18% were positive for hepatitis B markers. The highest seropositivity rates (33.9% and 27.7%) were found in siblings and parents, respectively, of the HBsAg+ persons. So far 77.5% of the susceptible contacts have used the opportunity for free vaccination.

CONCLUSION

The study has proven the importance of detecting HBsAg carriers and vaccinating their contacts. Special attention should be paid to immigrant families, particularly from Asia. Consistent vaccination of family and sexual contacts of HBsAg+ persons can contribute to a more rapid elimination of hepatitis B in the Czech Republic.

Prevalence of Cryptosporidium infection among livestock and humans in contact with livestock in Hamadan district, Iran, 2012

BACKGROUND

Cryptosporidium is a protozoan parasite causes cryptosporidial diarrhea, which is typically a short-lasting benign infection, but can become severe and non-resolving in immunocompromised individuals. The aim of the present study was to determinate the prevalence of Cryptosporidium infection in livestock and humans that were in contact with livestock in Hamadan district, Iran.

METHODS

In this cross sectional study a total of 660 fecal specimens were collected; 228, 195 and 237 from humans, whom raising livestock, their calves and lambs/goats, respectively in spring 2012. Samples were concentrated by formalin-ether concentration technique and examined using cold modified Ziehl-Neelsen staining method.

RESULTS

Two (0.87%) out of 228, 25 (12.8%) out of 195 and 6 (2.5%) out of 237 fecal samples of humans, calves and lambs/goats were positive for Cryptosporidium oocysts, respectively. There was no significant relationship between the infection to Cryptosporidium and demographic variables of humans. However, Cryptosporidium infection rate was higher in diarrheic calves (OR=3.81; 95% CI: 1.30, 11.21; P=0.010).

CONCLUSION

Despite studies conducted in some regions of Iran that resulted in a relatively high rate of infection in humans in contact with livestock, our results showed low prevalence and low carrier status in the asymptomatic persons in Hamadan region. Because the infection in calves and lambs/goats was relatively high, these animals could be probable reservoir of infection for humans in this area.

The infectivity and pathogenicity of a foot-and-mouth disease virus persistent infection strain from oesophageal-pharyngeal fluid of a Chinese cattle in 2010

BACKGROUND

Foot-and mouth disease (FMD) is an acute, febrile, and contagious vesicular disease affecting cloven-hoofed animals. Some animals may become persistent infected carriers when they contact FMD virus (FMDV), and persistent infected animals are a dangerous factor to cause FMD outbreak.

FINDINGS

300 OP (oesophageal-pharyngeal) fluid samples were collected from cattle without clinic symptom after one month FMD circulated in 2010 in China. A FMDV strain was isolated when a positive OP sample was passed in BHK21 cell line. The strain, named O/CHN/2010/33-OP, was detected to be O/Myanmar/1998 lineage with VP1 DNA sequence comparison. In order to testify its infectivity, two cattle were challenged with OP fluid and three pigs were put into the same pen for direct contact infection. The result showed that one of the cattle and one of the pigs appeared FMD clinic symptoms respectively. Furthermore, two cattle (three pigs were also put into the same pen for direct contact infection) and three pigs were inoculated with O/CHN/2010/33-OP cell passaged strain. The result showed that one of the challenged pigs appeared FMD clinic symptoms. Two cattle and three pigs in the same pen did not appeared FMD clinic symptoms, but the sera antibody and their OP fluid of two cattle were positive. Meanwhile, the spinal cords of three pigs in the same pen with two cattle were positive detected with multiplex- RT-PCR.

CONCLUSION

The persistent infection strain O/CHN/2010/33-OP has infectivity and pathogenicity to cattle and pigs, and infected cattle may transmit the virus to pigs although its virulence was lower than the circulated strain O/CHN/Mya98/2010.

Biosecurity-based interventions and strategies to reduce Campylobacter spp. on poultry farms

The prevention and control of Campylobacter colonization of poultry flocks are important public health strategies for the control of human campylobacteriosis. A critical review of the literature on interventions to control Campylobacter in poultry on farms was undertaken using a systematic approach. Although the focus of the review was on aspects appropriate to the United Kingdom poultry industry, the research reviewed was gathered from worldwide literature. Multiple electronic databases were employed to search the literature, in any language, from 1980 to September 2008. A primary set of 4,316 references was identified and scanned, using specific agreed-upon criteria, to select relevant references related to biosecurity-based interventions. The final library comprised 173 references. Identification of the sources of Campylobacter in poultry flocks was required to inform the development of targeted interventions to disrupt transmission routes. The approach used generally involved risk factor-based surveys related to culture-positive or -negative flocks, usually combined with a structured questionnaire. In addition, some studies, either in combination or independently, undertook intervention trials. Many of these studies were compromised by poor design, sampling, and statistical analysis. The evidence for each potential source and route of transmission on the poultry farm was reviewed critically, and the options for intervention were considered. The review concluded that, in most instances, biosecurity on conventional broiler farms can be enhanced and this should contribute to the reduction of flock colonization. However, complementary, non-biosecurity-based approaches will also be required in the future to maximize the reduction of Campylobacter-positive flocks at the farm level.

Transmission of MRSA between companion animals and infected human patients presenting to outpatient medical care facilities

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both human and veterinary medicine. The importance of companion animals as reservoirs of human infections is currently unknown. The companion animals of 49 MRSA-infected outpatients (cases) were screened for MRSA carriage, and their bacterial isolates were compared with those of the infected patients using Pulsed-Field Gel Electrophoresis (PFGE). Rates of MRSA among the companion animals of MRSA-infected patients were compared to rates of MRSA among companion animals of pet guardians attending a “veterinary wellness clinic” (controls). MRSA was isolated from at least one companion animal in 4/49 (8.2%) households of MRSA-infected outpatients vs. none of the pets of the 50 uninfected human controls. Using PFGE, patient-pets MRSA isolates were identical for three pairs and discordant for one pair (suggested MRSA inter-specie transmission p-value = 0.1175). These results suggest that companion animals of MRSA-infected patients can be culture-positive for MRSA, representing a potential source of infection or re-infection for humans. Further studies are required to better understand the epidemiology of MRSA human-animal inter-specie transmission.

[Influencing factors of mother-infant vertical transmission of hepatitis B virus]

OBJECTIVE

To study the factors influencing mother-infant vertical transmission of hepatitis B virus (HBV).

METHODS

A total of 635 pregnant women with chronic hepatitis B or chronic asymptomatic HBV carriers were enrolled. The rate of HBV infection was compared between the infants born from the pregnant women of different HBV-DNA load, different ways of delivery and different liver functions at birth and 3 months after birth. The newborn infants were routinely injected with hepatitis B immunoglobulin (200 IU) and hepatitis B vaccine (10 μg) within 12 hrs of birth. The newborns presenting HBV infection within 24 hrs of birth by serum test were re-injected with hepatitis B immunoglobulin (200 IU) 14 days after birth.

RESULTS

The rate of HBV infection in infants with maternal HBV-DNA load >10(5) copies/mL was higher than in those with maternal HBV-DNA load ≤ 10(5) copies/mL at birth (14.4% vs 4.1%; P<0.01) and 3 months after birth (4.7% vs 0; P<0.01).The rate of HBV infection at 3 months was lower than at birth in both groups. The rate of HBV infection in infants born by natural labor was higher than in those born by caesarean birth at birth (P<0.05), however, by 3 months after birth, the rate of HBV infection between the two groups was similar. The rate of HBV infection was higher in infants born to chronic asymptomatic HBV carrier mothers than that in infants born to chronic hepatitis B mothers at birth (P<0.01), but there were no significant differences in the two groups 3 months later.

CONCLUSIONS

The maternal HBV-DNA load is correlated with the rate of HBV infection of infants. It might thus be an effective way to reduce the rate of HBV infection in infants by decreasing maternal HBV-DNA load. With the administration of hepatitis B immunoglobulin and hepatitis B vaccine, the delivery way and the liver function of pregnant women may not to be factors influencing mother-infant HBV vertical transmission.

Ethical issues in preventing mother-to-child transmission of hepatitis B by immunisation

Without intervention, a pregnant woman who is a chronic hepatitis B carrier is at risk of transmitting hepatitis B and of her infant becoming a chronic carrier and having a significantly increased lifetime risk of developing liver cancer or cirrhosis. Hepatitis B vaccine and immunoglobulin reduce the risk of the baby becoming a carrier, but with only a short window period after birth to deliver this potentially life-saving intervention. We reviewed the evidence on the magnitude of the risk. If the carrier mother is e antigen positive (highly infective), the calculated risk to the infant without intervention is 75.2%, reduced to 6.0% by giving vaccine and immunoglobulin at birth. If the mother is surface antigen positive but e antigen negative, the risk to the infant without intervention is 10.3%, reduced to 1.0% by giving vaccine and immunoglobulin. If vaccine is accepted but immunoglobulin refused, as for example by some Jehovah's Witnesses, the risk to babies of e antigen positive mothers is reduced to 21.0% and to babies of e antigen negative mothers to 2.6%. These figures can be used to inform parents and as a possible basis for child protection proceedings if parents decline vaccine and/or immunoglobulin. We argue from the perspective of the best interests of the child that the severity of the condition justifies initiating child protection proceedings whenever a baby is born to a hepatitis B carrier mother and, despite concerted attempts to persuade them, the parents refuse vaccine and/or immunoglobulin.

Infant colonization by Staphylococcus aureus: role of maternal carriage

Infant colonization by Staphylococcus aureus has not been adequately investigated. In this study, we aimed to define determinants associated with the carriage of S. aureus in early infancy. Serial nasal swabs were collected from 128 infants and their mothers at months 0, 6, and 12 postpartum. S. aureus isolates were characterized by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), spa typing, and the presence of chromosomal mecA and of Panton-Valentine leukocidin (PVL) genes. S. aureus was isolated in 17.7% and 15.7% of swabs from infants and mothers, respectively. Carriage rates were higher in infants with carrier mothers, non-smoking mothers, and many siblings. Persistent carriage rates were higher in infants with carrier or non-smoking mothers. S. aureus typing revealed identical strains in 10/15 investigated infant-mother pairs. Among 19 investigated S. aureus isolates from infants, ten harbored mecA and two harbored PVL genes, and these determinants were concomitantly present in isolates from mothers. Resistance to methicillin was 43.6% among all isolates from infants. In conclusion, isolates from infants were commonly identical to isolates from their mothers, pointing to a principal role of maternal carriage in S. aureus colonization in infants.

[Genetic characteristics of Neisseria meningitidis strains obtained from healthy carriers during meningococcal infection outbreaks]

AIM

Genetic and antigenic characterization of Neisseria meningitidis strains isolated during meningococcal infection outbreaks from individuals in contact with patients with generalized form of meningococcal infection.

MATERIALS AND METHODS

Strains obtained in 2007 - 2009 in Moscow during examination of individuals that were in contact with patients during meningococcal infection outbreaks were analyzed. Multilocus sequence typing, genetic subtyping and typing of VR fragment (FetA) techniques were used.

RESULTS

Data regarding investigated strains were submitted to the database at http://pubmlst.org/neisseria/. Previously undescribed sequence types were found in 12 strains, sequence-type could not be determined in 2 strains, 2 strains lacked VR fragment (FetA). Serogroup A meningococci had "P1.5-2,10: F3-5" antigenic profile and belonged to ST-75 and ST-3349 sequence-type, these data does not support the emergence of epidemically significant strains in the territory under surveillance. All typed serogroup C strains and 1 serogroup B strain are of "ST-41/44 complex/Lineage 3" clonal complex. Subtypes of serogroup C meningococci strains match subtypes of strains that cause generalized forms of infection, while serogroup B strains isolated from the carriers and strains isolated from the patients had different antigenic profiles. Ungrouppable strains had notably higher level of genetic and antigenic diversity: only 6 of 16 strains (37.5%) could be sequence-typed using earlier data, all these strains are of clonal complex "ST-53 complex" that consists mostly of strains isolated from the carriers. CONCLUSION. Ratio of meningococci population circulating in Moscow and subpopulation capable of causing generalized form of meningococcal infection (GFMI) is different for meningococci of various serogroups. Ungrouppable strains isolated from the carriers are highly different from strains causing GFMI.

Reduction of hepatocellular carcinoma in childhood after introduction of selective vaccination against hepatitis B virus for infants born to HBV carrier mothers

OBJECTIVE

A nation-wide prevention program utilizing passive-active immunoprophylaxis for high-risk babies against maternal HBV transmission was introduced in Japan in January of 1986. The prevention program was expected to eradicate HBV-related hepatocellular carcinoma (HCC). The aim of this study was to evaluate the effect of this selective prevention program against maternal HBV transmission on the occurrence of HBV-related HCC.

METHODS

We reviewed the annual reports from a nation-wide survey of childhood solid tumors that was reported in the Journal of the Japanese Society of Pediatric Surgeons during the 28 years period from 1981 to 2008. The number of HCC cases were grouped for every 5-year period with an additional period of the past 3 years and compared with those of hepatoblastoma.

RESULTS

The reported number of children with hepatoblastoma in each period was constant during the 28 years study period. In contrast, both the number of patients with HBV-related HCC and the ratio of HBV-related HCC to hepatoblastoma gradually decreased over the study period, with a significant drop in the last two periods ranging from 2001 to 2008 (p < 0.001).

CONCLUSION

The prevention program against maternal HBV infection of infants born to HBV carrier mothers may have decreased the occurrence of HBV-related HCC in childhood.

Dogs as potential carriers of infectious bursal disease virus

In this study, the possibility that dogs could eventually be carriers of infectious bursal disease virus (IBDV) after having eaten (voluntarily or accidentally) IBDV-infected chicks has been evaluated. A single Beagle dog was fed chicks infected by a very virulent IBDV strain (vvIBDV). Afterwards, the presence and viability of IBDV in the faeces was assessed. Viable vvIBDV was detected in the dog's faeces for 2 days after the initial ingestion, which indicates excretion of vvIBDV. Comparison by molecular techniques of the administered and excreted virus using reverse transcription-polymerase Chain reaction and enzymatic digestion confirmed that the initial virus maintained the same characteristics after being excreted. We believe that this study could be of great interest for a better understanding of the epidemiology of IBD disease on farms where dogs live close to avian facilities.

[Evaluation of Quantiferon-TB Gold and tuberculin skin test in patients with tuberculosis, close contact of patients, health care workers and tuberculosis laboratory personnel]

Tuberculin skin test (TST) has been used effectively for a long time, despite inherent sensitivity and specificity limitations. Patients with a positive TST without active tuberculosis are identified as having latent tuberculosis infection. Identifying patients with latent tuberculosis infection with this test is an important part of control of the disease. A whole-blood inferferon gamma (IFN-γ) assay, the Quantiferon TB Gold test (QTG; Cellestis, Australia) which is a promising in vitro diagnostic test for the identification of latent tuberculosis infection (LTBI), has potential advantages over the TST. This test includes Myobacterium tuberculosis specific ESAT- 6 and CFP-10 antigens. The aim of this study was to compare the results obtained by QTG and TST in active tuberculosis (TB) patients, close contacts of patients, health care workers and tuberculosis laboratory personel. Twenty-six patients with active pulmonary TB, 6 close contacts of those patients, 11 health care workers with contact to TB patients and 8 TB reference laboratory personnel were included in the study. Prior to administration of the TST, blood samples were drawn from each participant for QTG test. All subjects were asked for BCG vaccination history and examined for a BCG scar. All individuals had a BCG scar. The QTG assay was performed in whole blood samples according to manufacturer's instructions. The agreement between TST and QTG was measured with kappa statistical analysis. In active TB patients (true-infected cases) TST (PPD) positivity was found 34.6% (9/26) while QTG positivity was 65.3% (17/26). Although the positivity rate was higher in QTG test, this difference was not found statistically significant (p > 0.001). TST and QTG positivity rates for health care workers, close house contact of TB patients and TB laboratory staff were as follows, respectively; 36% (4/11) and 27% (3/11); 16.6% (1/6) and 83% (5/6); 37.5% (3/8) and 75% (6/8). The mean PPD diameter was 11 mm in QTG negative group and 14 mm in QTG positive group with a statistically significant difference (p < 0.001). However, there was no statistical significance between QTG positive and negative groups by means of age (p ≥ 0.05) and gender (p < 0.001). In conclusion, QTG assay was superior to TST in its ability to detect LTBI and active TB infection, not to be affected with BCG vaccination, to discriminate responses due to non-tuberculous mycobacteria, and to avoid variability and subjectivity associated with application and reading the TST. Besides, QTG assay needs only one visit to the test unit. However, its being expensive than TST and requirement for special equipments and skilled laboratory personnel, are among the disadvantages of QTG assay.

An experimental model to evaluate Mycoplasma hyopneumoniae transmission from asymptomatic carriers to unvaccinated and vaccinated sentinel pigs

The objective of this study was to determine the effect of vaccinating susceptible animals on the transmission of Mycoplasma hyopneumoniae from experimentally infected pigs during the chronic phase of infection. Thirty-six seeder pigs were experimentally infected with M. hyopneumoniae. Eighty and 200 d post-infection (dpi) 18 seeder pigs were placed in direct contact with 15 vaccinated and 15 unvaccinated age-matched naïve animals. Direct animal contact occurred over 14 d. Pigs were euthanized at the end of the contact period and bronchial swabs were collected and lung tissue examined. At 94 dpi, 15 out of 15 unvaccinated sentinels and 14 out of 15 vaccinated sentinels tested positive for M. hyopneumoniae by nested polymerase chain reaction (N-PCR). At 214 dpi, M. hyopneumoniae DNA was detected by PCR in 8 out of 15 unvaccinated and 6 out of 15 vaccinated sentinels. Vaccination against M. hyopneumoniae did not prevent colonization of sentinels in contact with infected animals. Transmission of M. hyopneumoniae from asymptomatic carriers to unvaccinated and vaccinated sentinels was not different.

Pre-elimination stage of malaria in Sri Lanka: assessing the level of hidden parasites in the population

BACKGROUND

With the dramatic drop in the transmission of malaria in Sri Lanka in recent years, the country entered the malaria pre-elimination stage in 2008. Assessing the community prevalence of hidden malaria parasites following several years of extremely low transmission is central to the process of complete elimination. The existence of a parasite reservoir in a population free from clinical manifestations, would influence the strategy for surveillance and control towards complete elimination.

METHODS

The prevalence of hidden parasite reservoirs in two historically malaria endemic districts, Anuradhapura and Kurunegala, previously considered as high malaria transmission areas in Sri Lanka, where peaks of transmission follow the rainy seasons was assessed. Blood samples of non-febrile individuals aged five to 55 years were collected from randomly selected areas in the two districts at community level and a questionnaire was used to collect demographic information and movement of the participants. A simple, highly sensitive nested PCR was carried out to detect both Plasmodium falciparum and Plasmodium vivax, simultaneously.

RESULTS

In total, 3,023 individuals from 101 villages participated from both districts comprising mostly adults between the ages 19-55 years. Out of these, only about 1.4% of them (n = 19) could recall having had malaria during the past five years. Analysis of a subset of samples (n = 1322) from the two districts using PCR showed that none of the participants had hidden parasites.

DISCUSSION

A reservoir of hidden parasites is unlikely to be a major concern or a barrier to the ongoing malaria elimination efforts in Sri Lanka. However, as very low numbers of indigenous cases are still recorded, an island-wide assessment and in particular, continued alertness and follow up action are still needed. The findings of this study indicate that any future assessments should be based on an adaptive sampling approach, involving prompt sampling of all subjects within a specified radius, whenever a malaria case is identified in a given focus.

Population mobility, globalization, and antimicrobial drug resistance

Population mobility is a main factor in globalization of public health threats and risks, specifically distribution of antimicrobial drug-resistant organisms. Drug resistance is a major risk in healthcare settings and is emerging as a problem in community-acquired infections. Traditional health policy approaches have focused on diseases of global public health significance such as tuberculosis, yellow fever, and cholera; however, new diseases and resistant organisms challenge existing approaches. Clinical implications and health policy challenges associated with movement of persons across barriers permeable to products, pathogens, and toxins (e.g., geopolitical borders, patient care environments) are complex. Outcomes are complicated by high numbers of persons who move across disparate and diverse settings of disease threat and risk. Existing policies and processes lack design and capacity to prevent or mitigate adverse health outcomes. We propose an approach to global public health risk management that integrates population factors with effective and timely application of policies and processes.

Prevalence of methicillin-resistant Staphylococcus aureus colonization in horses in Saskatchewan, Alberta, and British Columbia

This study estimated the prevalence of methicillin resistant Staphylococcus aureus (MRSA) in nasal swabs of 458 horses in western Canada. The rate of colonization was 1.3% +/- 5.84% [95% confidence interval (CI)], a rate similar to those reported elsewhere. Colonization tended to be transient and seemed unrelated to stress or administration of antimicrobials. Five of the 6 isolates were Canadian epidemic MRSA-5, a human clone that appears to predominate in horses in North America. The other isolate was spa type 539 (t034), a sequence type 398 strain, and this is the first report of this clone in horses in North America. Surveillance is warranted because of the potential of MRSA to cause disease in horses and humans.

Serum ALT Levels as a Surrogate Marker for Serum HBV DNA Levels in HBeAg-negative Pregnant Women

In Stockholm, Sweden, the majority of pregnant women positive for hepatitis B surface antigen (HBsAg) are hepatitis Be antigen (HBeAg) negative. Newborns to HBeAg positive mothers receive vaccination and hepatitis B immunoglobulin (HBIg). Newborns to HBeAg negative mothers receive vaccine and HBIg only if the mothers have elevated ALT levels. The aim of this study was to retrospectively evaluate ALT levels as a surrogate marker for HBV DNA levels in HBeAg negative carrier mothers. Altogether 8947 pregnant women were screened for HBV markers from 1999 to 2001 at the Virology Department, Karolinska Hospital. Among mothers screened 192 tested positive for HBsAg (2.2%). 13 of these samples could not be retrieved. Of the remaining 179 sera, 8 (4%) tested positive for HBeAg and 171 (95.5%) were HBeAg negative. Among the HBeAg negative mothers, 9 had HBV DNA levels > 10(5) copies/ml, and of these 7 had normal ALT levels indicating low sensitivity of an elevated ALT level as a surrogate marker for high HBV DNA level. Furthermore, no correlation was found between ALT and HBV DNA levels. Hence, it is concluded that the use of ALT as a surrogate marker for high viral replication in HBeAg negative mothers could be questioned.