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Derek Evans

Welcome to Evans Travel Health

Blog     posted on Wednesday 4th August 2021

       How to prepare for Travel Medicine post-Covid

"We are all aware of that the impact of Covid infections has had on travel and continues to do. With the advent of vaccination programs and sophisticated testing and recording systems in place travel is starting to increase.

However the types of travel such as short haul continues to expand according to the determination of national governments whilst long haul remains dormant. The traveller groups have changed and the emphasis on routine vaccinations being sought by first time travellers going to exotic destinations has shifted to business and essential workers.

With this in mind the marketing of any specific travel medicine services will need to understand these changes. Following lockdowns and extended restrictions many travellers are now attempting to visit families and friends (VFRs) who they have only seen through video links. These VFRs will be a key target group during the revival of travel medicine demands and services.

A key part of the practitioners will be the flexibility to react to short time departures and supply necessary vaccines and medication where required. This parallels with the quick turn around that Covid tests are required for entry into another country before departure from the UK. It seems that a mix of PCR and rapid antigen tests are required within a range of departure times from 24 to 96 hours before departure.

The underlying point here is that this increased cost needs to be allowed for during any travel consultation and also the returning costs of testing and/or isolation. It is unlikely that these costs will be removed in the short term and certainly Covid will become another disease to be routinely covered during a travel medicine risk assessment."


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Infectious disease reporting- malaria on the rise again

Posted on October 26, 2016 at 5:35 AM Comments comments (676)


The recent publication for week 42 of the NOIDS (Notification of Infectious Diseases) report, highlights all diseases that should be reported by GP practices to public health authorities.

When diseases directly related to travel are extracted from this report, then facts such as acute meningitis are down compared to last year, as is typhoid fever (presumed contracted abroad), food poisoning, tetanus and tuberculosis. The only disease that bucks this trend is malaria with a 13.6% increase on last year.

With a reduction in the number of areas reported as requiring malaria prophylaxis in the world, then this raises the questions regarding the accuracy of information from these areas or indeed if a mis-perception is occurring in high risk areas that malaria is reducing?

The national report for malaria in returning patients rose in 2015 when compared to 2014 and the highest geographic risk area was from western and central Africa. These countries have not changed their advice on malaria prevention during this time and therefore the change is either by an increased volume of visitors or in the understanding of prevention.

With the emphasis on Zika prevention in the Americas; the focus on dengue and chikunguya in SE Asia is it possible we have taken our eye off the ball when considering malaria in Africa? In this day and age with large sums of money invested in malaria reduction to local populations; the continuing trend of rising reports could be due to larger numbers of visitors or improved reporting?

Whatever the reason further investigation needs to be undertaken to explain the rising number of malaria reports against a trend of reduction in other disease reporting.

Water purification - The Fourth Vaccine?

Posted on September 27, 2016 at 12:35 AM Comments comments (172)

Water purification - The Fourth Vaccine?


Much has been written and taught about the need to avoid water borne infections and also of the requirement to adequately re-hydrate when travelling abroad. When researching material for articles that I have written on this subject earlier then it became apparent that as travel health professionals we know but do not appreciate the detailed differences between all of the methods of water purification, and the claims that manufacturers have on specific products.


In the last month on the ISTM information site there have been comments given by specialists to use iodine (a chemical banned several years ago) to continue to purify water. Other evidence given was based on personal opinion of the user, often through the ease of use of product but very little was provided in the way of scientific assessment and evaluation. Can we therefore expect travellers to have the same level of understanding of their water needs as vaccinations if the travel health professional cannot provide the scientifically based detail regarding water purification methods and products.


For example, we know that boiling water can be highly successful in providing safe water, but also we know that it does not remove tastes or debris in the water. Like wise the use of chlorine based products is restricted if levels of debris appear or low temperatures and may not remove some organisms. The use of ultra-violet sources is again limited by the turbidity of the water and the need to carry spare batteries or recharge a solar cell (no much good at night or under a jungle canopy). Filtration appears to be a better method of providing safe water but here again many products claim to remove bacteria and Protozoa but stop short at viruses. There is only one single product on the market that meets and exceeds the Environmental Protection Agency (EPA) standards on water purification and that stands alone as the Aquapure Traveller, which I have written about before.


With the increasing amount of evidence of fake, counterfeit water now being sold; how can we as travel health professionals allow travellers to continue to travel under the illusion that bottled water is as safe as at home, especially when they are unable to identify the counterfeit. Is now the time to raise the discussion about water safety as part of the travel health assessment? The sale of a reputable product that purifies water at source becomes as important, as does the discussion about vaccine prevention of a single disease. A water purifier is able to cover prevention of far more diseases than a single specific vaccination and now could be termed the fourth vaccine.


It was interesting to note that at a recent presentation given at the Faculty of Travel Medicine, Glasgow a very highly respected member of the travel health professions quoted " After clean water, vaccination is the most important public health measure", indicating the importance of water discussion within the consultation.


Now is the time to start changing the attitudes and beliefs of travellers, that bottled water cannot be relied upon to be always safe, cannot be assumed this is of the same standard that is in their home country and difficult to identify. Therefore they need to consider water purification at the same level as vaccination.


Malaria imported into the UK 2015- Public Health England, July 2016

Posted on July 25, 2016 at 10:55 AM Comments comments (1173)

The recent publication by Public Health England (PHE) has indicated a decrease in the number of confirmed cases of malaria reported in the UK, but with 6 deaths from malaria in the past year.

This may be interpreted by some as an assumption we are getting better at preventing the disease and others will highlight the reduction in some countries of the world of the risk levels of malaria as seen in Vietnam and Cambodia earlier this year.


Whereas it is always welcome to see a reduction in the national picture of a notifiable disease there remains some details that should not be overlooked. At face value it might be considered that the increase in the number of deaths to 6 last year was a negative but when viewed over a period of time this is inline with the average trend for that period.

Importantly is that the surveillance system estimates it captured only 56% of the information and of these only 15% were correctly reported.


From a clinical perspective the largest proportion of reports indicated falciparum malaria, which accounted for all 6 deaths, coming from the region of West Africa. Children under the age of 18 years accounted for 11% of reported cases (160).

From the reporting over 80% of travellers had visited family or relatives and almost two thirds were from the African continent. The scary facts are that 93% were non-White British VFR travellers, with up to 85% not having taken any prophylactic treatment.


Sadly this highlights the ongoing need for all travel health practitioners to maintain their vigilance with all travellers going to malarial areas and their intentions to prevent infection. From my own personal experience in clinic, I continue to see families booking last minute holidays, turning up at clinics with enough money for yellow fever vaccinations but unable to purchase other vaccinations or antimalarials that would be advised. When talking with the parents it often appear that they are travelling in the next few days; families at the destinations have advised them on their local protocols for malaria control leading to misinformation and increased risk.


This is not a new problem, the issue with VFR travellers as been raised and addressed many times before; however we do not appear to have made progress into the education of the travellers. The traditional methods of information are currently reliant on the traveller making an initial contact with a health care professional. With the introduction of online booking of air fares etc this reduces the opportunity for an intervention for travel advice. Perhaps now is time to turn our attention to working with colleagues in the airlines or operating with professional associations such as ABTA to assist in highlighting the risk, as they are the first contact point and with such booking suggesting a referral to a travel health professional for further advice. This is already covered in the ABTA Code of Conduct to all of its members but would benefit from a a designed list of contacts (national and local) which can be issued at each booking, created and maintained by travel health profession, that can be given to any traveller.

Water- Travellers assumption of safety

Posted on June 22, 2016 at 8:40 AM Comments comments (0)

Much has been written, published, and spoken, about the need to inform travellers of the safe use of water and access whilst abroad. This is usually a final piece of information after the discussion of vaccines, antimalarials, and bite prevention, but is equally important, as evidenced by the need to discuss water borne diseases, typhoid and HepA, early in the consultation.

Following the responses from travellers seen as patients, the attitude to water appears to be:

. Tap water is unsafe and should be avoided

. Bottled water is safe as an alternative

. Water purification is too costly/time consuming/complicated

. Bottled water is safe as an alternative

. Hydration may need to be increased above the levels of the U.K.

. Bottled water is safe to use


This reliance and dependence on bottled water took me to research this further and I now conclude that there is bottled water and water that is bottled and these are often far apart. The assumption that bottled water is safe comes from the marketing and branding within the UK ,that is strictly controlled along with the regulation of the supply. These standards are not always the same in other countries, where we are all aware of the scams of counterfeit water and hence my term of water that is bottled. Last year a study in Pakistan found that 11% of bottled water was microbiologically or chemically contaminated and there were several arrests of traders exploiting the bottled water, by producing water in bottles from unlicensed sources.


The point of this is that apart from the global green issue (most developing countries do not have plastic re-cycling plants) is that travellers dependency on bottled water is flawed, as the standards can be no better than local tap water and there is no way to establish the authenticity.


This leads to the question what should we be advising? The obvious first point of call is to challenge the assumption on safe bottled water and then recommend alternative water purification techniques, which are often regulated by the additional cost. Cost effectiveness appears to be a filtration system with water bottle. There are several of these on the market, however FitForTravel and the NHS indicate that those with MAD technology have a superiority in the levels of organism removal.


The impact to travellers of aircraft mosquito control

Posted on May 19, 2016 at 11:15 AM Comments comments (0)


Recently I undertook a flight from an island off the north west African coast, which remains a dependency of an EU country. Upon closing the cabin doors the entire cabin, including passengers, was sprayed by the aircrew following an announcement that this was a measure required by the International Health Regulations (IHR).


Further investigation reveals that in February 2016, following the emergence of the Zika virus threat, the IHR Emergency Committee met and directed that the standard WHO recommendations of disinsection of aircrafts was implemented in order to attempt to control the Aedes species of mosquito. The process of spraying safely (called disinsection) was to be done to WHO Pesticide Evaluation Scheme standards.


So, imagining the unsuspecting travellers, perhaps with young families sitting on a return journey from a potential Zika area. The questions raised will normally be what are they using and is it harmful to humans, before understanding the reasoning why.


The WHO recommends the following products for disinsection:

. D-Phenothrin technical grade

. 1R-trans-phenothrin technical grade

. Permethrin technical grade


The first 2 products are man made insecticides of the pyrethrums family that kill by direct contact. They are considered to be less toxic to mammals due to higher body temperature, body size, and a lower sensitivity to the chemicals. The US Enironmental Protection Agency (EPA) classifies phenothrin as not likely to be a human carcinogen by all routes of exposure. ( The WHO hazard classification of d-phenothrin is "unlikely to present an acute hazard in normal use" (


Permethrin is a long established contact insecticide widely used for its contact ability on clothing and camping products. Like other pyrethroids, less than 1% of permethrin is absorbed through the skin, and although there were no specific lung absorption test results, the greatest amounts of eaten permethrin is found after 3-4 hours and is excreted mainly in the urine ( The US EPA classifies permethrin as "likely to be carcinogenic to humans" if it was eaten. This result is based on a reproduced study from rats but has not been determined in humans. There have been no published studies on inhaled aerosol formulations.


For travel heath professionals the key points that can be taken from this experience are:

1. Travellers returning from areas with Zika transmission should expect aircraft to be disinsected before take off. This may be a new measure, not seen before, and the traveller needs to understand the reason to control the mosquito vector.

2. The products used should be from the WHO approved list which are indicated to not to provide a greater risk if used in the aerosol form in the normal use patterns.

3. People at risk of respiratory diseases should be advised of cabin disinsection and the need to take appropriate precautions before spraying commences.





Posted on April 20, 2016 at 10:40 AM Comments comments (142)

The current outbreak of Yellow Fever (YF) in Angola and the subsequent transmission by travellers to other countries (travellers reported in China) raises questions to the the global spread of diseases around the world. This is not a new topic and we can refer back recently to the SARS and Avian flu situations; however the problem remains with the speed of travel against the detection, diagnosis and announcements of infectious disease conditions by the home country.


With the Aedes mosquito also being the lead vector in dengue and Zika virus infections then the same principles appear again. The host country will wish to protect its infrastructure from loss of travellers dollars/pounds/euros at the same time maintaining it's agreed status of reporting of infectious diseases to the WHO. This may explain the so-called rapid spread of Zika in the currently reporting areas but it also raises the question of reporting the presence of Aedes aegyptii in other modern first world countries.


Closer to home this mosquito species is reportedly found in the southern areas of France, Italy and Greece but without the Zika virus. The reported Zika cases of in these countries are coming from travellers who have been to exposed in countries where the virus already exists. At a recent conference in Nepal, an expert speaker indicated that there were 2 different strains of the Zika virus, these being the African one and the Asian one, the latter being that which is currently infecting Central and South America. Therefore a transmission has occurred form one geographical zone to another. The transmission timing is unknown but was considered to be before the recent FIFA World Cup.


Drawing parallels would be considered as inaccurate due to other varying factors. But from a epidemiological point of view there is a risk that Zika could appear in the Southern European zone in the next few years and therefore what would be the impact of travellers to these areas who traditionally have not used insect bite prevention measures.

Bite prevention and awareness has always been and will remain a valuable message to any traveller. In light of the ability of the vectors to move swiftly around the world, now is the correct time to raise the awareness of applications of DEET and Picaridin; use room control measures at night and wear appropriate clothing during the feeding times of the mosquito.




High Altitude medicine workshop in Kathmandu

Posted on March 17, 2016 at 3:25 AM Comments comments (1424)

Derek has recently returned from attending a High Altitude medicine workshop in Kathmandu, Nepal shorted by the world famous CIWEC Hospital and Travel Medicine Center. Here is his feedback on the workshop and thoughts.


Kathmandu at 1400 metres above sea level poses no threat of Acute Mountain Sickness (AMS) to travellers even though small differences in the exertion rates are noticed by travellers from the UK where Ben Nevis at 1344m and Snowdon at 1085m are considered to be at “altitude” and the general population live below 500metres.

The effects of moving to higher altitudes create physiological changes in the body which are widely documented and management of these come under either the prevention or treatment of 3 main conditions, AMS, HACE (High Altitude Cerebral Oedema) and HAPE (High Altitude Pulmonary Oedema).

Acclimatisation can be linked to the changes in the molecular switch of the Hypoxia Inductible Factor; improved oxygen transport and improved hypoxia tolerance. This academic style of presentation in reality covers the physiological changes in the body and its associated organs when presented by an oxygen debt.

AMS is considered to occur with an onset at 6 hours post arrival, peaking at 24 hours and then starting to reduce at 48 hours. Clearly this will have a significant impact on the traveller following a planned trek or expedition and being left behind for another group or waiting for the return of their group.

By contrast HAPE peaks between 18-96 hours and HACE 24-96 hours. With so much overlap there is a growing concern how to identify the difference between all 3 conditions and the treatment that may be required for each.

As with all recommended publications the gold standard treatment for all altitude related conditions is the reduction in height to improve acclimatisation and raise the oxygen saturation levels. As in all good pre-travel dialogues prevention is widely discussed with the use of acetazolamide published in many articles. Wisely this workshop also considered some of the alternative preventative treatments such as dexamthasone, ibuprofen, inhaled budesonide and sildenafil.

A guest speaker from the CIWEC clinic in Kathmandu applied some direction and reason to the range of treatments that are currently used for the above conditions. The most common cause of death relating to these conditions is the mis-diagnosis of the early symptoms and the realisation that at altitude not everything is altitude illness and that differential diagnosis needs to be understood between the conditions. The local treatment regime involved the sustained release preparations of nifedipine; dexamthasone; and sildenafil; but contra-indicated the use of diuretics and inhaled salmeterol.

With the new opportunities opening up for travelling so the range of people wishing to climb and ascend also increases. With this comes an increasing number of high risk patients that may include elderly and sick pilgrims; people with a history of blood conditions such as anaemia, DVT; people with severe asthma or COPD and hypertension and pregnant women all wanting to make an attempt to remain at altitude.

These bring with them extended circumstances of monitoring symptoms and the need for a consistent pathway of treatment if conditions take their toll on the physicality of the traveller. New strategies are being developed constantly for pre-acclimatisation and the encouragement should be to trial the use simulation of “fake altitude” by using tents that create hypoxic conditions whilst a home and before departure.

The final speakers concluded with the review of frostbite casualties seen at the CIWEC clinic and the understanding that this can b presented by continual heat production and heat conversion. The discussion over treatments for frostbite touched on the new idea of using iv prostaglandin with aspirin. As a specific non-Himalyan reference to altitude illness came from a speaker discussing the climb of Kilimanjaro (5895m) and the attempt to realise that this climb is completed in 5-6 days whereas by comparison an ascent to Everest base camp (5280m) is completed in 8-12 days. As expected the number of cases of AMS were in the range of 50-77%; a study found that as Kilmanjaro was in a National Park the Kenyan authorities charged a day rate for each traveller in the park to the tour guide. Further studies by the Wilderness Medical Group highlighted that 50% of the tour companies do not carry medicines to treat or prevent AMS and that staff are in sufficiently qualified to operate or use equipment such as oxygen. The conclusion for Kilimanjaro was that all travellers should carry there own suppl of acetazolamide, a medical kit and know how to use it and that the fast rate is driven by economic concerns and not beneficial to the traveller.

For further information on the details of this workshop and recommended doses for treatment and prevention contact Derek by email: [email protected]

Mosquito viruses - is this an opportunity to review our advice on insect repellents?

Posted on February 29, 2016 at 9:45 AM Comments comments (104)

Much has been written in the media about the incidence of Zika virus and its potential link to other neurological conditions, as highlighted in my blog of November last year.


As medical researchers investigate the claims of the links to these conditions we are no further forward in a treatment and unlikely to be for some months. Therefore travellers already booked and paid to travel to infected areas are seeking more information about bite avoidance which in itself is a good awareness, as this will also help to protect against other mosquito borne diseases such as malaria, dengue, yellow fever, Japanese encephalitis etc.


The down side however, is that the go to preparation has always been a DEET repellent and new travellers to this are becoming concerned about using a product on the skin that can damage synthetic material and has a strong odour. In the USA they appear to be more advanced with offering alternatives and in particular picaridin or icaridin in this country. Several systems sell this product and a recent Public Health England publication states that a 20% concentration is equivalent to efficacy with DEET. A further look at the research material available shows that picaridin has a superior effect to DEET when used to prevent arthropod bites as confirmed by the US military study.


However all the medical advice will fail if the patient/traveller does not use the product properly. Evidence suggests that picaridin is more user friendly on sensitive skin and by implication this would make it a better product for children and when used with sunscreen then another study shows it is superior to DEET in the protection against bites.


Although not a new product, picaridin seems to be coming out of closet and showing its rival that it is as good and in some cases superior; but ultimately those people travelling to the mosquito infected countries now have an alternative to consider when choosing their bite avoidance strategies.

Zika virus the risk and recent clinical updates

Posted on January 25, 2016 at 11:05 AM Comments comments (94)

As more countries in South and Central America report the incidence and detection of the Zika virus in mosquitoes, the need to know the detail of this infection is becoming more important. Recently reports have appeared on major news channels and daily newspapers indicating the possible link to microcephaly and highlighting the need of avoidance in these countries of women who are pregnant.


With the 2016 Olympics being held in Brazil later this year, then high levels of travellers will entering the country and possibly the infected areas that will increase with the risks of infection. Travel health professionals will be and are currently being asked about the risks and advice regarding the safety of travel. From early reports it appears that although the infection initially comes from the bite of the Aedes (sp) mosquito, there is also evidence that this infection can be passed inter-humanly.

A French specialist reports that the risk of transplacental transmission to the foetus is during viremia (when viruses enter and circulate within the bloodstream) is short (5-7 days) after the beginning of symptoms or 12 days after the mosquito bite. Therefore if the patient wishes to become pregnant a month after her return the specialist's comment is that there is a very low risk to the foetus. Tips would be extended if they used the advice of the ACMP to allow 3 months after leaving the infected area before conception.



With regards to cross infection, it is thought that urine is probably not infective, breast milk is not contra-indicated, however saliva and sperm have tested positive. These findings are published in papers on the CDC and in the Eurosurveillance websites.



Zika virus- is this something different to other mosquito viruses?

Posted on December 18, 2015 at 10:50 AM Comments comments (2)


With the introduction of the Zika virus into countries within Central and South America warnings have been placed by the CDC about protection against mosquito bites and rightly supporting the existing advice that is given against malaria, dengue and Chikungunya infections. Many will consider that Zika is yet another infection which coming from the Flavivirus genus and spread by the Aedes mosquito, would be expected to show similar characteristics.

More recently published data by WHO indicates an epidemiological alert for neurological syndrome, congenital malformations and Zika virus. As this warning continues, it suggests to prepare specialised care facilities and strengthen antenatal care. At the end of November the Ministry of Health Brazil reported 3 deaths associated with Zika virus and is investigating a link to increased congenital anomalies.

A search of WHO reports linked to dengue and Chikungunya fevers shows no reference to congenital malformations, indicating that this disease may differ from its cousins. More detailed work is required to determine if this an unique differentiating point for Zika and pregnant travellers in particular should be advised when travelling to the identified areas of this difference.




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