Research and analysis

HPR volume 8 issue 43: news

Updated 23 December 2014

1. Antenatal checks for environmental CO exposure: new algorithm for midwives

The latest in a series of tools developed to help healthcare professionals diagnose harmful exposure to carbon monoxide (CO) has been published by Public Health England [1].

The flowchart was developed following NICE’s recommendation that midwives test for smoking status in pregnant women using exhaled CO as an indicator [2]. In acknowledging the special significance for pregnant women of the hazard of CO generated by malfunctioning fossil and wood fuelled domestic heating appliances and faulty flues, it was recognised that whilst carrying out this test, midwives could identify cases of CO poisoning from exposure from non-tobacco sources [3,4].

Pregnant women are considered a susceptible group in respect of CO poisoning because fetal blood has a much higher affinity for CO than an adult’s. The fetus is therefore susceptible to the harmful effects of CO at lower levels of exposure than the mother. Maternal exposure has been linked to birth defects and other poor pregnancy outcomes including fetal and infant mortality.

Not only is CO more readily taken up by the fetus than by the mother but it is also released more slowly, therefore prolonging exposure of the fetus even after the mother is no longer being exposed. Use of the tool should help identify pregnant women who – although not active or passive smokers – may be being exposed to CO from faulty fossil or wood fuelled appliances and flues in their home.

The tool complements a joint letter on CO for healthcare professionals from the Chief Medical Officer, Chief Nursing Officer and Director of Nursing at the Department of Health and Public Health England (see: www.gov.uk/government/publications/carbon-monoxide-poisoning).

The tool for midwives – produced by PHE in consultation with the Department of Health and supported by the Gas Safety Trust – follows the format of other flowcharts created to assist GPs and emergency physicians, environmental health professionals, and nurses running smoking cessation clinics in diagnosing CO poisoning from both low level, chronic and high level, acute exposures.

As with the other tools, it describes sources of CO, symptoms which might indicate exposure to the gas; provides advice on the interpretation of breath test results; suggests questions pregnant women should be asked to establish whether CO poisoning should be suspected; recommends actions following diagnosis; and provides telephone numbers for services providing further advice and practical assistance.

A call for research in this area has been launched this week by the Gas Safety Trust: see: http://www.gassafetytrust.org/news-and-press/2014/gst-calls-for-applications.

1.1 References

1. PHE (2014). “Antenatal checks: carbon monoxide (CO)”.

2. . National Institute for Health and Clinical Excellence (2010).“Quitting smoking in pregnancy and after birth”.

3. Leeds NHS Trust (2014). “Leeds Community midwife’s carbon monoxide test saves lives of family”.

4. Kent NHS Trust (2014).“A new CO test saves life of pregnant mum and family”.

2. Tenth annual review of infections among UK blood, tissue and organ donors and transfusion recipients

The NHS Blood and Transplant (NHSBT)/PHE surveillance programme is a series of national schemes to monitor infections in blood, tissue and organ donors and transfusion recipients. Data from these schemes are distributed widely throughout the UK blood services and are used to inform donor selection practices and to improve blood and tissue safety. This news report summarises the contents of the tenth annual review of infections in blood/tissue donors that has been published on the PHE website [1].

The NHSBT/PHE Epidemiology Unit tenth annual review, “Safe Supplies: Reflecting on the Population”, describes infections among donors and transfusion recipients during 2013.

In addition, the report includes:

• the most recent estimated risk of current donation testing strategies not identifying a potentially infectious HBV, HCV or HIV window period blood donation;

• “horizon scanning” for new and emerging potential infectious threats.

The findings provide assurance that an extremely high level of safety is being maintained within the UK blood supply. The report also provides a solid base on which to build further reviews of donor eligibility to ensure that no donors are unnecessarily declined.

During 2013, over 2.3 million blood donations were tested in the UK, of which 230 were positive on mandatory testing. This is a rate of 10.1 confirmed positive donations per 100,000, which is almost unchanged form 2012. More than four of every five infections detected (84%) were among new donors, who comprised of approximately 15% of the donor population. Testing in the UK detected blood donations with markers for the following infections: HBV (64), HCV (57), HIV (16), HTLV (5) and treponema (88). As in previous years, the majority of infections in donors were chronic (87%), and previously undiagnosed. For HBV, HTLV and some HCV infections country of birth of the donor – or for HBV and HTLV, the country of birth of their mother –.was invariably found to be the probable source. Four acute and four occult HBV infections were reported.

Not all donors comply with the donor selection criteria and each year a small number of infected donors are found to have been non-compliant. In 2013, 20 donors with markers of infection were classified as non-compliant. The most common reasons such donors subsequently gave were that they thought either that their personal risk was low or that the criteria were not applicable to them. The change to the MSM donor selection criteria in 2011 continues to be monitored; as yet, there has been no increase in the number or proportion of male donors with markers of infection.

All UK blood services screen platelets for the presence of bacteria, although currently only NHSBT and SNBTS report to the surveillance scheme. The positive rates in the platelets screened by NHSBT in 2013 (n=285,292) remained low and similar to 2012 levels, with 0.02% of apheresis and 0.07% of pooled platelets confirmed positive. The majority of isolates were identified as Propionibacterium species; these organisms are rarely associated with transfusion transmitted infection. Bacterial screening also prevented the transfusion of platelet units containing potentially pathogenic organism including Staphylococcus aureus and Streptococcus bovis. SNBTS did not report confirmed growth from any of the 15,555 screened packs.

In 2013, additional testing allowed just 91,000 donations to be released for issue. None of the donations tested positive for T. cruzi or WNV, but Malarial antibodies were detected and confirmed in 0.94% of donations tested. Additional testing for anti-HBc was carried out for those donors with specific risks in the last 4-12 months and included donors with a history of tattoos, body piercing, and acupuncture or endoscopy. These donations numbered 29,331 and 0.07% were found to be anti-HBc positive with insufficient immunity to allow use.

The risk of a contaminated unit entering the UK blood supply continues to decrease and is currently estimated at one HBV every year, one HCV every 17 years and one HIV every three years. The recent decrease in risk for hepatitis B is in part due to a shorter estimated window period used in the calculation.

Transfusion transmitted infections (TTI) in the UK remain rare; in 2013, one probable hepatitis B transfusion transmitted infection (TTI) was reported following a transfusion in 2012 and one pending 2012 investigation was confirmed as an HEV transmission. The UK blood services do not currently screen for hepatitis E. Bacterial screening of platelets has resulted in potentially harmful contaminated platelet packs being removed from the blood supply. There have been no reported, confirmed bacterial TTIs since 2009, although in 2013 there was a false negative result on bacterial screening where Staphylococcus aureus was not detected in two platelet doses from one apheresis collection. The units were not transfused but had the potential to cause severe morbidity and mortality in a recipient.

During 2013, 1323 deceased solid organ donors were tested across the UK with 4,501 organs donated from 1257 donors. Information is available for initially reactive screening test results among the 1323 proceeding donors: 11 donors with HCV antibodies (0.8%), one donor with HIV antigen/antibodies (0.1%) and one HTLV positive donor (0.1%).

The number of positive markers of infection in deceased and living tissue donors and cord blood donors is low, but because of the small numbers of donors tested the rates of infection are higher than those for blood donations. In 2013 among donations tested by NHSBT, five living surgical bone donors had positive markers for HCV (17 donors reported HCV positive between 2001 and 2013) and nine deceased donors had markers of HBV infection. As in previous years, few cord blood donors have markers of infection; in 2013 there was one donor who was HCV positive and one with HTLV infection; a further 19 had malarial antibodies reflecting past exposure to malaria rather than ongoing infection.

In 2013, MERS-CoV, a respiratory infection similar to SARS, emerged in the Middle East. Currently this appears to be of low risk to the blood supply. Of more concern was the spread of chikungunya virus across the Caribbean and in 2014 to Florida. This spread could have significant impact on donors if additional donor selection measures are required; the situation is being closely monitored. There is continuing surveillance in place for West Nile Virus, dengue and other insect-borne diseases which continue to spread to new areas of the world.

2.1 Reference

1. “Safe supplies: reflecting on the population”. Annual review from the NHS Blood and Transplant/Public Health England Epidemiology Unit, 2013 (November 2014). Downloadable at: https://www.gov.uk/government/collections/bloodborne-infections-in-blood-and-tissue-donors-bibd-guidance-data-and-analysis.

3. Ebola virus disease: international epidemiological summary

Up to the end of 9 November, a total of 14,098 clinically compatible cases (CCC) of Ebola virus disease (EVD), including 5,160 deaths have been reported in the six currently affected countries (Guinea, Liberia, Sierra Leone, Spain, the USA and Mali) and two previously affected countries (Nigeria and Senegal) since December 2013.

There are some early indications that case incidence is no longer increasing nationally in Guinea and Liberia. However, transmission remains intense in Conakry and Macenta in Guinea, and in Montserrado district in Liberia. In Sierra Leone, incidence continues to increase, particularly in the western and northern regions (see PHE map).

To date, a total of 19 cases have been cared for outside of Africa; 14 repatriated cases (treated in USA, Spain, UK, Germany, France and Norway), two imported cases (both diagnosed in USA) and three incidents of local transmission (in Spain and USA).

The table below summarises Ebola virus disease international epidemiological information as at 9 November 2014

Country	Total CCCs	Cases in past 21 days	Total deaths
Guineau	1878	325	1142
Liberia	6822	466 *	2836
Sierra Leone	5368	1211	1169
Mali	4	3	4
Nigeria	20	0	8
Senegal	1	0	0
Spain	1	0	0
USA	4	0	1
TOTAL	14 098	2005	5160

* Liberia’s data is for the previous 18 days only.

Further information on the international epidemiological situation can be found in PHE’s weekly Ebola Epidemiological Update.