High Public Health Risk Research Articles

High genetic compatibility and increased pathogenicity of reassortants derived from avian H9N2 and pandemic H1N1/2009 influenza viruses

H9N2 influenza viruses have been circulating worldwide in multiple avian species and repeatedly infecting mammals, including pigs and humans, posing a significant threat to public health. The coexistence of H9N2 and pandemic influenza H1N1/2009 viruses in pigs and humans provides an opportunity for these viruses to reassort. To evaluate the potential public risk of the reassortant viruses derived from these viruses, we used reverse genetics to generate 127 H9 reassortants derived from an avian H9N2 and a pandemic H1N1 virus, and evaluated their compatibility, replication ability, and virulence in mice. These hybrid viruses showed high genetic compatibility and more than half replicated to a high titer in vitro. In vivo studies of 73 of 127 reassortants revealed that all viruses were able to infect mice without prior adaptation and 8 reassortants exhibited higher pathogenicity than both parental viruses. All reassortants with higher virulence than parental viruses contained the PA gene from the 2009 pandemic virus, revealing the important role of the PA gene from the H1N1/2009 virus in generating a reassortant virus with high public health risk. Analyses of the polymerase activity of the 16 ribonucleoprotein combinations in vitro suggested that the PA of H1N1/2009 origin also enhanced polymerase activity. Our results indicate that some avian H9-pandemic reassortants could emerge with a potentially higher threat for humans and also highlight the importance of monitoring the H9-pandemic reassortant viruses that may arise, especially those that possess the PA gene of H1N1/2009 origin.

Rats as Indicators of the Presence and Dispersal of Pathogens in Cyprus: Ectoparasites, Parasitic Helminths, Enteric Bacteria, and Encephalomyocarditis Virus

Rodents play an active role in the transmission of a number of zoonoses by harboring and disseminating the pathogens involved, either through their biological materials or via their ectoparasites. Hence, the spatial and seasonal distribution of potential agents of zoonoses may be studied by examining their distribution in the rodent vectors and their ectoparasites. A surveillance was conducted in wild rodents in 51 different areas of Cyprus, an island ecosystem, to monitor the reemergence of Echinococcus granulosus and Encephalomyocarditis virus (pathogens that have been eradicated from Cyprus), to study the presence and dispersal of Salmonella spp. (a bacterium found in patients and poultry in the island), as well as to investigate the presence of helminth parasites and rodent ectoparasites. Biological material collected from 625 rodents, examined macroscopically, microscopically, and after culture, showed that the most widespread pathogens encountered in wild rats (Rattus rattus and Rattus norvegicus) were helminth parasites, found in 92 animals (three helminth species found for the first time in Cyprus: Cysticercus fasciolaris, Hymenolepis diminuta, and Physalloptera spp.), and Salmonella spp., detected in the intestine of 56 rats (12 different Salmonella spp. and serotypes). None of the rodents were found infected with the cestode Echinococcus or Encephalomyocarditis virus, indicating that the control measures taken by the Veterinary Services on the island prevented its reestablishment despite changing conditions. The rodents were also free of the nematode Trichinella. Over 40% of the rats collected were infested with fleas, mainly Xenopsylla cheopis. The results, analyzed using the Geographical Information System technology, revealed two of the areas studied as high risk for public health.

Risk factors associated with porcine cysticercosis in selected districts of Eastern and Southern provinces of Zambia

To determine the risk factors associated with Taenia solium transmission in humans and pigs in the rural areas of Eastern and Southern provinces of Zambia, a questionnaire was administered in 788 households from 155 villages. Pigs were examined from 800 households. Tongue examination and enzyme-linked immunosorbent assay (Ag-ELISA) for the detection of circulating antigens of T. solium cysticerci were used to measure infection in pigs. A snowballing technique was utilised to select households with pigs. Prevalence of households with pigs infected with T. solium on tongue examination by district ranged from 12.7% to 32.1% with Ag-ELISA having a range of 30.0–51.7%. Of the total number of households visited, 18.8% and 37.6% had at least one pig positive for porcine cysticercosis on tongue examination and Ag-ELISA, respectively. Risk factors associated with T. solium infection were lack of pork inspection at slaughter (96.7%), consumption of pork with cysts (20.1%), selling of pork infected with T. solium cysticerci (18.3%), free-range husbandry system (83.2%) and absence of latrines (58.0). Free-range husbandry system (OR = 1.68; 95% CI = 1.36–2.07) was a significant risk factor for porcine cysticercosis in the surveyed areas. The result that pigs were mostly kept on free-range and semi-intensive husbandry systems may have permitted them to have access to eating human faeces that could be contaminated with tapeworm eggs. This study has shown that T. solium infection poses a high public health risk in the study areas and urban areas as well. We recommend that a human survey be conducted to verify the human exposure to taeniasis and/or cysticercosis in Zambia.

Desorption of polycyclic aromatic hydrocarbons from carbon nanomaterials in water

Desorption behavior of pyrene, phenanthrene and naphthalene from fullerene, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) was examined. Available adsorption space of carbon nanotubes (CNTs) was found to be the cylindrical external surface, neither the inner cavities nor inter-wall spaces due to impurities in the CNTs and restricted spaces (0.335 nm) of the MWCNTs, respectively. Desorption hysteresis was observed for fullerene but not for CNTs. Deformation-rearrangement was proposed to explain the hysteresis of polycyclic aromatic hydrocarbons (PAHs) for fullerene, due to the formation of closed interstitial spaces in spherical fullerene aggregates. However, long, cylindrical carbon nanotubes could not form such closed interstitial spaces in their aggregates due to their length, thus showing no significant hysteresis. High adsorption capacity and reversible adsorption of PAHs on CNTs imply the potential release of PAHs if PAH-adsorbed CNTs are inhaled by animals and humans, leading to a high environmental and public health risk.

Nipah virus: Impact, origins, and causes of emergence

Nipah virus is an emerging zoonotic pathogen that causes severe febrile encephalitis resulting in death in 40% to 75% of human cases. Nipah virus is considered a biosafety level-4 pathogen and is listed as a select agent with high risk for public health and security due to its high mortality rate in people and the lack of effective vaccines or therapies. The natural reservoir for Nipah virus and related members of the genus Henipavirus are fruit bats of the genus Pteropus. Nipah virus emerged in Malaysia in 1998 as a porcine neurologic and respiratory disease that spread to humans who had contact with live, infected pigs. Research reviewed in this paper suggests that anthropogenic factors, including agricultural expansion and intensification, were the underlying causes of its emergence. Nipah virus has caused five subsequent outbreaks between 2001 and 2005 in Bangladesh. Here, it appears to have spilled over directly from bats to humans, and person-to-person transmission is evident suggesting a heightened public health risk.

Efficacy of enhanced outreach counseling to reenroll high-risk drug users 1 year after discharge from treatment

Because discharged methadone maintenance patients represent a population at particularly high public health risk, the authors studied such patients 1 year after their discharge from a methadone program. The locations of 94 of 110 discharged patients were successfully determined 1 year after discharge. Nine (10%) of these patients had died, 37 (39%) were already reenrolled in treatment, and 7 (7%) did not require treatment. The 41 remaining subjects were randomly assigned to either the enhanced outreach counseling condition (N = 27) or a standard referral condition (N = 14). Within 2 weeks following this intervention, 17 (63%) of the 27 patients in the enhanced outreach counseling program and one (7%) of the 14 patients not in the program had reenrolled in treatment. These data suggest that enhanced outreach counseling may be an effective outreach strategy as well as a risk-reduction for discharged methadone maintenance patients.

Evaluation of Commercial Enzyme Immunoassay (EIA) and Immunofluorescent Antibody (IFA) Test Kits for Detection of Cryptosporidium Oocysts of Species Other than Cryptosporidium parvum

A commercial enzyme immunoassay (EIA) (ProSpect Rapid Assay), a direct immunofluorescence antibody (IFA) test for stool testing (MERIFLUOR Cryptosporidium/Giardia), and an indirect IFA test for environmental testing (Hydrofluor-Combo Cryptosporidium/Giardia) were evaluated for detection of low public health risk Cryptosporidium oocyst isolates, and for C. parvum oocyst isolates from human and bovine feces that represent a high public health risk. There was no cross-reactivity of EIA with ova of eight medically important helminths, three Eimeria species oocysts, Sarcocystis cruzi sporocysts, and two Candida sp. isolates. All nine snake oocyst isolates (C. serpentis), two of seven lizard oocyst isolates, one turtle oocyst isolate, two avian oocyst isolates (turkey, C. meleagridis), one C. wrairi oocyst isolate from guinea pigs, one C. muris oocyst isolate from hyrax, one heifer C. muris isolate, and two C. muris-like oocyst isolates from a camel were positive by both IFA tests; six of these 19 oocyst isolates were EIA-positive. There was no difference in the sensitivity and specificity between direct and indirect IFA tests. The sensitivity of the EIA and both IFA tests to the C. parvum oocysts was 100%. The EIA showed less cross-reactivity with the non-C. parvum oocysts (24%) than direct or indirect IFA (76%), and was less sensitive to those isolates (20%) than both IFA tests (63%). A simulated sampling model for high and low public health risk Cryptosporidium oocysts showed that the low risk oocyst isolates may constitute up to 35% of all positive environmental samples by direct or indirect IFA determination, and up to 12% of all EIA positive samples. This study indicates a superiority of direct and indirect IFA and EIA for screening of human-or-bovine-origin fecal specimens, whereas testing of environmental samples may lead to misidentification of medically important isolates. The results demonstrated that the EIA kit can more accurately identify environmental samples containing oocytes pathogenic for humans than both IFA tests. The specificity of commercially available diagnostic kits to C. parvum should be critically examined for cross-species identification before they are recommended or adopted for use in testing environmental samples.