Tag Archives: microbial contaminants

Transmission of Helicobacter pylori

Mladenova I, Durazzo M. Transmission of Helicobacter pylori. Minerva Gastroenterol Dietol. 2018 Feb 19. doi: 10.23736/S1121-421X.18.02480-7.

The exact modes and routes of transmission of Helicobacter pylori (H. pylori) infection remain unproven. Studies showed that H. pylori bacteria can spread directly from one person to the other, or indirectly from an infected person to the environment. Presently, interpersonal pathways are more probable than environmental exposure routes. Person to person transmission can be mainly fecal-oral or oral-oral. In the last 30 years many authors have investigated the main potential sources of H. pylori infections, vectors and risk factors for both fecal-oral and oral-oral routes of transmission, eating of contaminated food, drinking of contaminated water, and exposure to animals. They have tried to isolate H. pylori from feces, saliva, dental plaque. These aspects are the basis for the effective prevention of both H. pylori acquisition and gastroduodenal pathology associated with it. These issues will be discussed in this narrative review.

Malaria Deaths Decline in Age of Global Warming

“In the visualisations below we provide estimates of the total number of deaths from the World Health Organization (WHO) from 2000 to 2015, and the Institute of Health Metrics and Evaluation (IHME), Global Burden of Disease (GBD) from 1990 to 2016. These estimates are notably different across various countries which affects the total number of reported deaths. IHME figures, as shown below, tend to be higher; they report deaths greater than 720,000 in 2015 versus only 438,000 from the WHO.” click here

Drinking water contamination with Helicobacter pylori, Peru

Boehnke KF, Brewster RK, Sánchez BN, Valdivieso M, Bussalleu A, Guevara M, Saenz CG, Alva SO, Gil E, Xi C. An assessment of drinking water contamination with Helicobacter pylori in Lima, Peru. Helicobacter. 2018 Jan 8. doi: 10.1111/hel.12462.

BACKGROUND: Helicobacter pylori is a gut bacterium that is the primary cause of gastric cancer. H. pylori infection has been consistently associated with lack of access to sanitation and clean drinking water. In this study, we conducted time-series sampling of drinking water in Lima, Peru, to examine trends of H. pylori contamination and other water characteristics.

MATERIALS AND METHODS: Drinking water samples were collected from a single faucet in Lima’s Lince district 5 days per week from June 2015 to May 2016, and pH, temperature, free available chlorine, and conductivity were measured. Quantities of H. pylori in all water samples were measured using quantitative polymerase chain reaction. Relationships between the presence/absence and quantity of H. pylori and water characteristics in the 2015-2016 period were examined using regression methods accounting for the time-series design.

RESULTS: Forty-nine of 241 (20.3%) of drinking water samples were contaminated with H. pylori. Statistical analyses identified no associations between sampling date and the likelihood of contamination with H. pylori. Statistically significant relationships were found between lower temperatures and a lower likelihood of the presence of H. pylori (P < .05), as well as between higher pH and higher quantities of H. pylori (P < .05).

CONCLUSIONS: This study has provided evidence of the presence of H. pylori DNA in the drinking water of a single drinking water faucet in the Lince district of Lima. However, no seasonal trends were observed. Further studies are needed to determine the presence of H. pylori in other drinking water sources in other districts in Lima, as well as to determine the viability of H. pylori in these water sources. Such studies would potentially allow for better understanding and estimates of the risk of infection due to exposure to H. pylori in drinking water.

Pepper mild mottle virus as a surrogate of human enteric viruses

Shirasaki N, Matsushita T, Matsui Y, Yamashita R. Evaluation of the suitability of a plant virus, pepper mild mottle virus, as a surrogate of human enteric viruses for assessment of the efficacy of coagulation-rapid sand filtration to remove those viruses. Water Research. 2017 Nov 21;129:460-469. doi: 10.1016/j.watres.2017.11.043.

Here, we evaluated the removal of three representative human enteric viruses – adenovirus (AdV) type 40, coxsackievirus (CV) B5, and hepatitis A virus (HAV) IB – and one surrogate of human caliciviruses – murine norovirus (MNV) type 1 – by coagulation-rapid sand filtration, using water samples from eight water sources for drinking water treatment plants in Japan. The removal ratios of a plant virus (pepper mild mottle virus; PMMoV) and two bacteriophages (MS2 and φX174) were compared with the removal ratios of human enteric viruses to assess the suitability of PMMoV, MS2, and φX174 as surrogates for human enteric viruses. The removal ratios of AdV, CV, HAV, and MNV, evaluated via the real-time polymerase chain reaction (PCR) method, were 0.8-2.5-log10 when commercially available polyaluminum chloride (PACl, basicity 1.5) and virgin silica sand were used as the coagulant and filter medium, respectively. The type of coagulant affected the virus removal efficiency, but the age of silica sand used in the rapid sand filtration did not. Coagulation-rapid sand filtration with non-sulfated, high-basicity PACls (basicity 2.1 or 2.5) removed viruses more efficiently than the other aluminum-based coagulants. The removal ratios of MS2 were sometimes higher than those of the three human enteric viruses and MNV, whereas the removal ratios of φX174 tended to be smaller than those of the three human enteric viruses and MNV. In contrast, the removal ratios of PMMoV were similar to and strongly correlated with those of the three human enteric viruses and MNV. Thus, PMMoV appears to be a suitable surrogate for human enteric viruses for the assessment of the efficacy of coagulation-rapid sand filtration to remove viruses.

Economic Assessment of Cryptosporidiosis Outbreak, Ireland

Chyzheuskaya A, Srivinas R, O’Donovan D, Prendergast M, O’Donoghue C, Morris D. Economic Assessment of Waterborne Outbreak of Cryptosporidiosis. Emerging infectious diseases. 2017 Oct;23(10):1650-1656. doi: 10.3201/eid2310.152037.

In 2007, a waterborne outbreak of Cryptosporidium hominis infection occurred in western Ireland, resulting in 242 laboratory-confirmed cases and an uncertain number of unconfirmed cases. A boil water notice was in place for 158 days that affected 120,432 persons residing in the area, businesses, visitors, and commuters. This outbreak represented the largest outbreak of cryptosporidiosis in Ireland. The purpose of this study was to evaluate the cost of this outbreak. We adopted a societal perspective in estimating costs associated with the outbreak. Economic cost estimated was based on totaling direct and indirect costs incurred by public and private agencies. The cost of the outbreak was estimated based on 2007 figures. We estimate that the cost of the outbreak was >€19 million (≈€120,000/day of the outbreak). The US dollar equivalent based on today’s exchange rates would be $22.44 million (≈$142,000/day of the outbreak). This study highlights the economic need for a safe drinking water supply.

C. hominis, C. parvum dominant in China

Feng Y, Xiao L. Molecular Epidemiology of Cryptosporidiosis in China. Frontiers in microbiology. 2017 Sep 6;8:1701. doi: 10.3389/fmicb.2017.01701.

Molecular epidemiology of cryptosporidiosis is an active research area in China. The use of genotyping and subtyping tools in prevalence studies has led to the identification of unique characteristics of Cryptosporidium infections in humans and animals. Human cryptosporidiosis in China is exemplified by the high diversity of Cryptosporidium spp. at species and subtype levels, with dominant C. hominis and C. parvum subtypes being rarely detected in other countries. Similarly, preweaned dairy calves, lambs, and goat kids are mostly infected with non-pathogenic Cryptosporidium species (C. bovis in calves and C. xiaoi in lambs and goat kids), with C. parvum starting to appear in dairy calves as a consequence of concentrated animal feeding operations. The latter Cryptosporidium species is dominated by IId subtypes, with IIa subtypes largely absent from the country. Unlike elsewhere, rodents in China appear to be commonly infected with C. parvum IId subtypes, with identical subtypes being found in these animals, calves, other livestock, and humans. In addition to cattle, pigs and chickens appear to be significant contributors to Cryptosporidium contamination in drinking water sources, as reflected by the frequent detection of C. suis, C. baileyi, and C. meleagridis in water samples. Chinese scientists have also made significant contributions to the development of new molecular epidemiological tools for Cryptosporidium spp. and improvements in our understanding of the mechanism involved in the emergence of hyper-transmissible and virulent C. hominis and C. parvum subtypes. Despite this progress, coordinated research efforts should be made to address changes in Cryptosporidium transmission because of rapid economic development in China and to prevent the introduction and spread of virulent and zoonotic Cryptosporidium species and subtypes in farm animals.

Climate Changes and Human Pathogens Study Misleading

This study (here) of the affect of climate sensitivity on human pathogens is a literature search. The basic thesis being presented is that global warming will result in greater numbers of pathogens which in turn will result in more human illness. This line of thinking makes several assumptions. It might be useful in generating hypotheses for future surveillance but is inadequate for predicting future illness. Why? Because literature reviews are limited by what is called “publication bias”. That is, only certain articles and studies are publishable and others important studies relevant to this review are not published. Studies with negative findings are rarely published. Also, some studies are screened out because of reviewer bias. We can learn from this review but its interpretation is limited. 

Indeed, survival of some pathogens may be expected to decrease.  The authors themselves acknowledge:

“Although this study identifies a high degree of climate sensitivity among important pathogens, their response to climate change will be dependent on the nature of their association with climate drivers and impacts of other drivers.”