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Why are vaccines less effective in the developing world?

Posted on 7 June, 2018 at 10:55 Comments comments (0)



Often a question that is implied but never answered is why there appears to be lower success rates in vaccination programmes in developing countries when compared to developed countries.


A recent piece of research from the University of Minnesota Medical School has compared the response rates between patients in Uganda and the USA. The study concludes that some diseases such as malaria, TB and those caused by parasites may damage the lymph node structures which are important centres for developing immunity after a vaccine.


At a deeper level the study evaluated the 2 groups to find that every Ugandan patient showed a difference such as fibrosis and anatomy changes of their secondary lymph nodes compared to USA patients.


Following a trail with yellow fever vaccine, antibodies were measured after 60 days to determine that lymphoid abnormalities were associated with immune dysfunction. The study suggests that common infections in the developing world maybe a limiting factor for in the development of immune response of other vaccines.


If this study is true the implications for new vaccines against malaria, HIV, dengue, etc would need to be designed to either avoid the secondary sites or be unaffected by any damaged tissue.

 

WHO- World Malaria Report 2017

Posted on 2 May, 2018 at 10:15 Comments comments (0)


WHO- World Malaria Report 2017 .This annual report has previously been the online publication of a single document of many pages available through the WHO web site and not easily accessed.

This year the WHO have produced the report in an app version which can be downloaded on Apple and Android platforms. This far easier to use app includes headings of

Quick Stats- estimated annual cases 216 million, 90% of which occurred in the WHO African region. Along with India this region showed 16 countries with indigenous malaria; however this was Dow by 18% from 2010. Estimated deaths were 445000, mainly from the P falciparum in Africa and P vivax in SE Asia and the Americas.

Regions- the African region reports all Sub-Saharan countries with a risk of malaria. In the Americas most countries in central and South America and islands off shore. Similarly countries in SE Asia and Western Pacific regions report malaria presence.

Indicators- for more detailed analysis the presence of falciparum and vivax by country and the accuracy of the detection by slide observation and rapid diagnostic kits (RDT). The policy section discusses the availability of free malaria testing services, supply of treated nets and treatment/surveillance policies.

This overview of the world standards and variance between countries can provide the supporting information especially when discussing longer term travellers and those travelling as VFRs returning to family in high risk areas.

Sourcing non-microbiologically contaminated water when travelling.

Posted on 31 January, 2018 at 9:15 Comments comments (2)



Some unpublished research following a survey of travellers indicated that their intention when travelling was to rely on the purchase of bottled water to rehydrate. The survey indicated that the largest group intending to rely on this were in the 20-29 age group, and travelling on holiday or for business for a period of less than 2 weeks. This defined a rough profile of a group wanting to use bottled water in place of that from the tap or local source. The destinations were not recorded beyond the regional level not the remoteness of the journey which may influence the choices of water sourcing.


The dependence on bottled water was considered mainly from the expectation that bottled water standards were the same across all countries and that water in a bottle was microbiologically safer than locally sourced or tap water. A meta-analysis survey of research reports have highlighted countries where unsafe microbiological water has been tested and includes areas of common destinations for travellers. The WHO standards identify unsafe water as only having E.coli coliforms present in a sample. Of the samples that tested positive to the standard, there were also a number that tested positive to other species such as Pseudomonas and Enterococci, but these are not included within the WHO.


A recent report from WHO (Progress on drinking water, sanitation and hygiene, 2017), shows in  annex 3 a guide to the purity of tap water found in each country by average, rural and urban sources. The target is to gain 0% of coliforms in the At least Basic Group with water being present on the premises and available when needed. By reviewing this list countries progress towards safer water can be established over a period of time.


As in all things within travel health this is a guide, and is sub-categorised according to location. When considering the reliance of the traveller on bottle water then the improving levels of local water with supplementary purification methods can provide a cost effective alternative to bottled water with unknown levels of contamination.


The role of the healthcare professional still remains to highlight the differences in water quality between home and destination and also to advise on maintaining the safety of supply. The question of whether they will conform to the advice given, has been studied and reported before. This is often the answer to the questions relating to water purification and travellers diarrhoea., All of the observed studies have reported travellers not following the advice and experiencing some form of gastro-intestinal upset that may be linked to prohibited food or water sources.


UK MALARIA CHANGES- impact for travel health professionals with differing online advice

Posted on 1 November, 2017 at 9:30 Comments comments (1)

The new Advisory Committee on Malaria Prevention (ACMP) have released the 2017 guidelines based on the results of 2016. Interestingly enough in its summary, the focus is upon the realisation from WHO that nearly 90% of global cases have originated from Africa and this contingent remains the focus for both residents and returning travellers. The report goes on to indicate that ACMP have evidence to suggest that there is a real reduction in other areas such as SE Asia and South America; and the reality now is that the greater risk of being bitten lies with mosquitoes which transmit dengue, chikungungya and zika viruses.

The report continues with endorsement of the use of mefloquine despite the continued negative media press in the UK, as a useful product when considered with a risk assessment. It then raises the question why would this not be a good product without a risk assessment and hence the argument could spiral. In short the public’s memory of harmful properties remains historically for a lot longer than preventative power. One only has to look at the child vaccination rates for MMR and hear again the question from a parents concerning links to autism and nothing regarding the high proportion of children who are not suffering from a life threatening infection.

The guidance refers in several places to the new OTC brand of atovaquone/proguanil available. Not a new concept of deregulating an established POM medication to be more freely available to the travelling public. However it must be considered a thorn in the side of some industry leaders that it can be supplied without a legal requirement to complete an in-depth risk assessment or by staff without accredited levels of advanced training.

The malaria guide goes onto describe the new malaria maps. As these are the latest updates made by a group of specialists they will form the basis of a reference point for many. However other specialists will have alternative interpretations of similar data leading to different recommendations in the same country for example Travax. Both sets of data are considered to be accurate however to the end user, whether it be a travel health specialist or a member of the public, then these online web sources cause confusion and it requires a single online web-based piece of advice for all to work with.

In the world where internet access can be found from a mobile phone, from sites in a multitude of countries, it is not uncommon now to receive patients coming in with preconceived ideas for malaria prophylaxis having done their own research. The difference between travel health advisory services between countries adds further confusion. This author frequently sees patients who have conceived ideas of malaria prophylaxis based on the American CDC site which does not necessarily reflect that of the UK. A clear example recently found was the use of anti-malarials recommended across India by the CDC following the realisation of an increase in faliciparum malaria. Whereas from the UK there are some small recognised pockets of high risk; the majority of the country can receive prophylaxis from bite avoidance measures. To reduce this confusion either the web servers need to highlight the source is from another country and may be different (very unlikely to occur) or within the clinics we need to be informing clients which of the online sources we are using and recording this.

The benefits would be that a traveller reflecting after a consultation would then look at the same site as used by the travel health professional and in the longer term a returning traveller would  reference the same site and have similar expectations. Therefore the question that is raised is how much benefit would be provided and is this something professionals should be adding to records?

HepA and HepB shortage - an opportunity?

Posted on 31 July, 2017 at 10:20 Comments comments (0)


Like many of us in travel health I am concerned about the the shortage of these vaccinations, especially when HepA is considered high risk in so many places. Upon reflection and following national guidance (UK) does this present a golden opportunity for travel health professionals to demonstrate the kind of assessment and rationalising that we have trained for? In a perfect world many will routinely follow the guidance issued by the respective agencies, but how many of us stop to question the risk of exposure the traveller of these diseases. Consequently this provides an opportunity to sharpen and hone the individual skills of risk assessing each traveller for the vaccines in relation to previous history, but more importantly to the risk of the disease.


Take for example HepA- widely recommended for all travellers to many destinations by the likes of Travax and NaTHNaC. The aetiology of the disease is that it does not manifest itself for 3-4 weeks post infection. Therefore for the traveller undertaking a 2-3 week trip to a risk area they will probably have returned home before the infection becomes apparent and medical care can be sought. It stands to reason when assessing risk these travellers could be considered low risk and an alternative source of avoidance would be to good food hygiene and possibly a water purification system which would also cover other non-vaccine preventable infections such as Campylobacter, Shigella and Giardia.


Likewise I often see patients referred to me for HepB rapid courses as they claim this is not supported by the NHS, and the staff experience is based on GUM clinic advice. Again a traveller needs to be assessed according to risk, a couple travelling together may be considered at lower risk for sexual transmission; likewise those who have no intention of being tattooed or having acupuncture. Therefore this leaves the risk (assuming no elective surgery) from an accident that may require a blood transfusion or the use of unclean needles. I receive many students attending school projects lasting a few weeks and requesting hepB, because they were advised by another health care professional. I do wonder if we are considering this as checklist vaccination or really investigating the true and real risk of exposure of this disease.



Whereas there is no correct or wrong way to manage these patients, there is a need to assume each is individual and therefore their risks will differ. However no course of vaccination is 100% effective and as we have often said before it is about the awareness of avoiding the risks which is more persuasive than any vaccination.


New guidelines for the prevention and treatment of Travellers Diarrhoea(TD)

Posted on 7 July, 2017 at 0:25 Comments comments (0)

At the recent CISTM meeting in Barcelona an expert panel reported back on a major review of TD. They concluded that prevention and treatment of TD requires action at the provider, traveller, and researchers. There is now strong evidence to suggest the effectiveness of Antimicrobial therapy in most cases of moderate to severe TD.


So what is classified as moderate TD- diarrhoea that is distressing or interferes with with planned activities. Severe TD is further classified as diarrhoea that is incapacitating or completely prevents planned activities.


The major changes to the supply of antibiotics are a reduction in the use of fluoroquinolones due to resistance and where prophylaxis is required the use of rifaximin is included. Azithromycin is now the antibiotic of choice for treatment of moderate TD and can be used with loperamide as an adjunctive therapy. When considering antibiotic regimes then single dose antibiotic doses can be considered using 1000mg of Azithromycin or 750mg of ciprofloxacin.


In summary providers need to consider the classification of TD and that the importance of using oral rehydration salts remains. Information needs to be given to each traveller when considering the use of antibiotics for TD regarding over use and creating multi-drug resistant bacteria. Loperamide may be used alone or with antibiotics in moderate to severe TD.



EVEREST- NEW KIDS ON THE MOUNTAIN

Posted on 6 May, 2017 at 0:15 Comments comments (1)

 



With this season's climbing season well on the way and expectations of summits in the next few days, is it not amazing to read that in between the serious climbers and outdoor specialists there are now breakfast trips to Everest Base Camp (EBC), as reported in a national newspaper.

 

The new breakfast club is a helicopter journey up to base camp for a 15 minute breakfast (tourists not sufficiently acclimatised at altitude cannot stay any longer) and then return to Kathmandu. The opportunity to take your selfie whilst in the snow, sipping champagne and eating a pre-cooked breakfast steps over the boundary of the technical explorer and shows how quickly the world is shrinking.

 

Ever since Sagamathar was renamed Everest, individuals have applied detailed planning to reach EBC. At that time the recommended trekking route took 10-12 days and was undertaken only by those who has the guile and want to achieve the trek.

 

With the new relaxation of helicopter flights along with the fun sense of quick adventures the new tourist is on the mountain. It does not require any further description of how the 2 different communities will consider the visit of the other to EBC. However there is a commonality that exists between them- both groups are travellers going for different reasons to the same location. Neither one can consider themselves to have ownership of the slopes nor indeed the access to EBC; however where a difference will occur is in the risk to acute mountain sickness (AMS) and the medical assistance required to support a patient.


The experienced traveller will be familiar with this altitude and will have acclimatised on their approach to EBC, to survive for up to several weeks before a summit attempt. Their body will have adjusted to the lower air pressures; they may take preventative medication and be used to the sleep disturbances that can occur at this altitude. Fast forward to the incoming helicopter flight of selfie seekers looking for an extreme exposure photograph. They will be required to disembark; take the selfies; consume a pop-up breakfast and embark again. All within 15 minutes; according to the advert to prevent signs of AMS.

 

Experience with any such prepaid party is that they will exhibit behaviours that want to push the time limits to the maximum and beyond. Where does this now place the patient who is late and starts to show AMS symptoms? The advice travel medicine specialists always suggest, is to move to lower altitude; but this is contrary to the grain of the selfie-seeker who has paid a large sum of money for the experience. With this type of risk taking and a longer period at altitude, the patient is likely to feel worse and they may not want to travel in a helicopter until feeling better. Hence we have the downward spiral of events with the potential of staff trying to persuade a noncompliant patient to leave and jeopardising the health of the passengers as they remain at altitude.


Whereas no-one has ownership of landing at EBC here is now a position where commercialism has pushed the boundary without fully advertising the risks that may occur if travellers are not compliant to specialist travel advice.


For the purist climber it remains an invasion of their domain, just as the British Climbing teams did when Nepal opened its borders in the last century. However the purist usually has a knowledge of survival skills required for this altitude. The new fast adventure group does not always have these developed skills and requires more advice and support in the correct attitude towards survival at altitude. These specialist tour operators need to be aware of the responsibility under the ABTA Code of Conduct to indicate a referral to travel health specialists.


(Reference:

http://www.dailymail.co.uk/travel/travel_news/article-4390132/Now-pop-Everest-BREAKFAST.html )


Reasons for not having Vaccines

Posted on 6 February, 2017 at 11:00 Comments comments (0)


 

This is an age old problem in travel health, in that the traveller gives reasons for not having vaccines and many opinions have been postulated why. It is a story that continues and recently in the Journal of Travel Medicine and Infectious Diseases(1), a report of a 10 member French family returning from Algeria where they had all been in contact with a rabid dog and received poor post exposure care.

 

A article published in the Journal of Travel Medicine(2) has recently looked at this situation again to try and establish the underlying reasons, rather than opinions for not having vaccines prior to travel. To provide some form of standardised approach traveller's were asked to reply to their refusal using one of 3 reasons; these being cost concerns, safety concerns, not concerned with the illness.

 

The cohort size of the study was around 24,500 patients and most commonly related to typhoid, hepA and influenza vaccines which were advised for their destination. Whereas we may have expected refusal to primarily being made due to financial considerations, the results showed that this was not the case and patients were more likely not to be concerned with with the risk of illness. In a further analysis it was determined that VFRs in low or medium human development countries were less likely to accept all of the recommended vaccines compared to non-VFR travellers.

 

So what can we conclude from these 2 studies. Firstly, the concern regarding the safety of vaccines does not appear to raise a concern. Following this is an excellent article in PLOS titled "Why Vaccines Don't Cause Autism" (3) which provides scientifically researched reasons with up to date articles. Secondly, both articles feature VFRs as having higher risks from non-vaccinations. Finally, the most common was a lack of concern relating to the illness reflecting that more information needs to be made available of diseases related to travel.

 

The solution to disease awareness in the UK is about developing a culture that when booking a foreign holiday, disease prevention is as high as a consideration as the purchase of sun block. Often this level of decision making can be initiated at the booking process and it is interesting to read the travel agents ABTA Code of Conduct Guidance which says in paragraph 2F

"Make sure that your clients are made aware of compulsory vaccinations etc. You should also advise clients to seek advice on recommended vaccinations and precautions from a health professional - either a GP, a practice nurse, a pharmacist or a travel health clinic - ideally at least eight weeks before departure "

Perhaps we can look at working with travel agents to improve the levels of advice.



References

1. Antwi S et al, 9th January 2017. Familial cluster of exposure to a confirmed rabid dog in travellers to Algeria. PMID 28089844

2. Lammert S et al, 2016. Refusal of recommended travel-related vaccines among US international travellers in Global TravEpi Net. Journal of Travel Medicine, doi 10.1093/jtm/taw075

3. Hoetz P, 2017, Why Vaccines Don't Cause Autism. http://blogs.plos.org/speakingofmedicine/2017/01/20/the-why-vaccines-dont-cause-autism-papers/

4. ABTA Code of Conduct Guidance. https://c0e31a7ad92e875f8eaa-5facf23e658215b1771a91c2df41e9fe.ssl.cf3.rackcdn.com/general/ABTA_Code_of_Conduct_Guidance_12082016.pdf

 

Mosquito vectored diseases- what have we learnt this year for 2017?

Posted on 21 December, 2016 at 4:40 Comments comments (0)


 

This year we have seen the rise and lately the fall of the incidence of zika reported infections; the rise in the frequency of reported dengue and chikungunya along with lesser known diseases such as West Nile fever appearing more frequently.

 

The appearance of these diseases is not unknown nor was undetected before. However; with zika appearing in Florida, rising dengue reports from India then the question must be, is this improved reporting or an entomological rise? Theories and reports  abound regarding the reasons for these and no empirical evidence as been produced either way.

 

What can be learnt is that is a genuine concern about increasing levels of mosquito borne infections are being noted and treated. The recent article in the Times of India asks the questions of the government and political members about who has the liability for these increases?

 

As health care professionals we can review what is known as fact. Part of the factual evidence is recording what has been successful and replicating that elsewhere. In September this year, WHO determined Sri Lanka as a malaria free country. Yet little has been highlighted how they achieved this notable status in adjacent countries.

 

Looking forward to 2017, in an attempt to support its residents, then other countries with rising levels of mosquitoes, could consider an approach such as the mapping of infected areas, especially those prone to the collection of water. The quick reporting of an outbreak, associated testing laboratories are all essential for the response to any infection, along with the early release of medical supplies.

 

All the clinical delivery will be undone without the parallel support of public health education of residents to remove stagnant water, continuing with the interior room spraying and where issued, the use of mosquito nets. The timing of this needs to happen in the drier seasons and if the politicians/healthcare teams wish to follow the lead in reduction of infection, timing could be the forum for delivery.

 

As many countries move into 2017 with a history of rising mosquito borne infections, a reflective review needs to occur. Public health education focuses on acting sooner rather than later and sharing experiences from other countries that have been successful. By making politicians/managers/healthcare teams accountable to deliver strategies, does this underpin the way to contain and reduce such infections?

 

DEET 100% - time for a change

Posted on 24 November, 2016 at 13:00 Comments comments (0)


 

For some considerable time the use of DEET in concentrations above 50% has been a concern for healthcare professionals when applied directly to the skin. This has followed some reports indicating that there may be an increased risk of systemic toxicity with dermal absorption.

 

Despite this evidence, manufacturers have continued to formulate products with claims of up to 100% DEET and indicated in packaging of its superior protection. When reviewing the activity of insect repellents, often the questions asked by travellers are how much is needed to achieve protection and how frequently does it need to be applied.

 

Like many drug pharmacokinetics there is a linear log dose concentration-dependent relationship between the dose of repellent applied and the percentage protection achieved which follows a standard log dose-response curve. Here the important point is the rate of loss of repellent from the skin which follows an exponential curve (as in first order kinetics). Following mathematical interpretations, in normal use, this would mean strengths of DEET above 50% do not offer a significant increase in protection time and that 30-50% will provide acceptable levels of protection for al least 4 hours, depending on amounts initially applied. (Ref: Goodyer L, 2004. Travel Medicine for Health Professionals. Pp142-149. London. Pharmaceutical Press).

 

From 1st January 2017 the EU Biocidal Products Regulations come into force which restrict the maximum concentration of DEET to 50%. Therefore all products with strengths greater than this will need to be removed from sale before this date. Products containing lemon eucalyptus and picaridin are unaffected by the regulations and remain for sale. The Advisory Council on Malaria Protection in their 2015 report highlight; lemon eucalyptus is equivalent to around 15% of DEET and that picaridin is reported as equivalent to DEET.

 

What of the future for DEET? To continue its use and provide a longer level of of protection, manufacturers are considering new techniques to extend the period of time between applications and ideas such as micro-encapsulation are now being being used in products.

 

Users or requests of higher (>50%) of DEET will now have to be advised that these strengths of DEET can no longer be supplied. The use of 50% applied correctly will give protection for up to 4 hours. The new formulations will give longer time protection whilst the alternative products may provide less dermal absorption.



 


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