Evans Travel Health

Click here to edit subtitle

Blog

view:  full / summary

Lest we forget...

Posted on 10 June, 2020 at 10:50 Comments comments (3)


Whilst the world is focussed on the covid 19 virus and the impact on society; little has been discussed regarding other virus infections which we already know more about. Last year we were all aware of the issue of dengue infection, the poor performance of the Denvaxia vaccine and the increasing number of areas reporting raised levels of infection despite increasing public health responses.

 

Coming forward 12 months from the traditional rainy season in SE Asia we have reports of Aedes infections bringing with them the traditional infections of dengue, chikungunya and zika. Even countries such as Singapore with high healthcare standards are reporting high levels of dengue with 9000 cases so far this year and a weekly reporting of over 700 cases. Other countries such as Thailand are reporting infections from all 77 provinces with a country total so far of +14000 cases.

 

So why are we seeing the continued rise. One of the possible answers comes from scientists in India who have identified that the Aedes mosquito has adapted its egg laying to the sides of water containers.

 

Originally mosquito eggs were considered to be laid in a raft on the water surface before maturing and some such as Anopheles and Culex continue to do so. The Indian discovery was that Aedes now lays its eggs on the side of the water containers so they can mature in wet or dry conditions as the water levels adjust up and down, surviving for up to 9 months in dry conditions.

 

The virus itself enters the eggs and develops inside these cells during the lean period so they are available to be released at day 1 of the maturation.

 

If this research is confirmed then it may require new guidance to be issued, this will include the wiping and cleaning out of water containers every 2-3 days and not just emptying them.

Common mosquito borne viruses- should they all be considered in pregnancy?

Posted on 5 March, 2020 at 0:40 Comments comments (0)


 

In 2015-2016 the world was awakened to the affects of the Zika virus in pregnant women and the devastating risk of microcephaly. Since that time the world has evolved into discussing the risks associated with mosquito transmitted Zika virus with pregnant travellers visiting high risk countries. The levels of risk in some countries has fallen as the attention to bite avoidance and counter-measures has increased. Now in 2020 the attention is currently on coronavirus and what are implications for global public health, yet does the risk from other mosquito borne infections remain consistent?

 

At the time of writing the global number of infections due to coronavirus is calculated around 80,000; yet in one country last year 30,000 cases of dengue were reported last year. The levels of Aedes borne infections (dengue, chikungunya) are increasingly being reported and appear to be rising, although this has to be balanced against a case for improved health reporting.

 

With the risk of these virus infections being spread pregnant women in high risk areas a recent paper has reflected on the levels of risk for dengue and chikungunya infections as well as Zika ( Dengue, Zika and chikungunya during pregnancy: pre- and post-travel advice and clinical management- Journal of Travel Medicine, 2019, 1–13).

 

In this paper the researchers have reviewed the pre and post travel advice of the 3 infections. Their main findings are that dengue may be associated with complications due to its infection risk of post-partum haemorrhage. Zika continues to be teratogenic and chikungunya although of lower risk during pregnancy carries a risk of infection at the time of labour. Therefore the risks from Zika continue and the risks associated with dengue may not be realised fully as the impact of risk from haemorrhage are not fully realised.

 

This impacts on the travel health professional in the advice they provide. Countries reporting a risk of dengue need to be highlighted to pregnant traveller due to the associated risks of potential haemorrhage. Whilst Zika, more importantly, highlights the teratological risks. All viruses have documented evidence of foetal transmission during pregnancy.

 

Therefore, although coronavirus is capturing the headlines currently, there is a need to be increasingly aware of mosquito borne viruses which have higher reported levels and their infection in pregnancy.

WHO- Neglected Tropical Diseases

Posted on 4 February, 2020 at 8:10 Comments comments (0)


In the current climate a lot of attention is focussing on the recent coronavirus outbreak form Wuhan, China. Whereas the global community is focussing on the rapid change necessary to control the spread of this infection, there is a need to retain the wider view of Neglected Tropical Diseases (NTD).

 

In January the WHO day for NTD went un-noticed by a lot of the media; however the 20 plus listed diseases/conditions remain a greater threat to the global community than the coronavirus outbreak.

 

The current NTD list covers infections that include:

Bacteria- trachoma, leprosy, Burundi ulcer,

Helminths- hookworm, ascariasis, filariasis, schistosomiasis, taeniasis

Protozoa- leishmaniasis, trypansomiasis

Viruses- dengue, chikungunya

Snake bite envenomation

 

It is estimated that 10% of the global population are suffering from one of the above infections and the all are in countries below the World Bank poverty line ($1.90/day).

 

These infections require substantial a international investment before eradication. The Gates Foundation has placed over $300million into a reduction of some of these and currently we are approaching the elimination of trypansomiasis in Africa and leishmaniasis on the Indian sub-continent.

 

Moving forward is the need to consider that financial investment into vaccines is the only method for reduction and final elimination. It is becoming evident of the need to combine other disease reduction streams such as the issuing of insect prevention bed nets and improved education on sanitation, washing and hygiene. These are supported by many other agencies who tackle the principles of adjusting the local cultures and beliefs to improve their own communities. Fundamental to these changes are the wish of the local communities to want to change; management of the change involving adjustments to existing cultures and the correct utilisation of products issued for disease reduction and control (eg bed nets).

 

Whilst the funding streams remain fragile due to economic pressures then the delivery of vaccines and chemotherapy will continue to suffer. Therefore a combined funded strategy has a place within the strategy for sustained delivery and progress in making changes utilising a global health pathway.

 

Ref

1. World Neglected Tropical Diseases day https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0007999

2. What constitutes a Neglected Tropical Disease https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0008001

 

 

Updates to European insect vectors and disease risks.

Posted on 4 December, 2019 at 14:20 Comments comments (0)


 

Recently announcements from Public Health England have highlighted the emergence of tick borne encephalitis cases in the UK and ECDC have raised the awareness of Zika virus in Europe.

 

The impact of global warming has been widely linked with increased temperatures and northern movement of insect vectors as these latitudes increasingly become warmer. The ECDC vector distribution analysis indicates that the mosquito species Aedes albopictus appears to survive better in cooler climates than its cousin A aegyptii. Although not considered as pathogenic as aegyptii, albopictus can still be linked to the provision of diseases such as dengue, chikungunya and zika.

 

The A albopictus distribution highlights a detection in Southern European countries (1), although this not correlate with reported levels of infections. A comparison between the reports of January and August 2019 appear to show very little difference in distribution, indicating that the vector presence may not be seasonal and now is annual.

 

Taking forward the same principle and comparing other insect vectors such as Ixodes, A aegyptii and Phelbotomus then the distribution characteristics can again be shown with a generalised northern movement (2). Again it must be stressed that although the vector is present does not mean that the disease is present and in the absence of vaccinations the protection measures must be the usual insect repellents.

 

One point that travel health practitioners must now need to consider is the pregnant traveller who changes her travel itinerary away from a high risk vector area and decides to travel to a considered potential safer area in Southern Europe?1. https://www.ecdc.europa.eu/en/all-topics-z/disease-vectors/prevention-and-control/vector-distribution-modelling

2. https://www.ecdc.europa.eu/en/search?s=Aedes+albopictus+distribution

 

Should Dengue vaccine be licensed for travellers from the UK?

Posted on 11 October, 2019 at 0:55 Comments comments (0)



The spread of the dengue virus is highly reported as rapidly increasing in many Asian countries in particular. Last week Bangladesh and Pakistan reported high levels of outbreaks exceeding the number of beds and medical facilities available to treat these patients. These countries are in addition to those reporting earlier in the year such as Philippines, Indonesia, Taiwan and India.


In  an article published last week there are references from France and Spain of patients returning home after contracting dengue abroad and a call for a rapid risk assessment process in case autochthonous cases develop.


Although currently the levels of the transmitting mosquito, Aedes albopictus, are low in Southern Europe, the impact of global warming and the climate is indicating a potential of this mosquito moving further north in the forthcoming years. In the USA for example the last 2 years have had reports of dengue in Florida and this year is the same with CDC recording watch levels on the infection.


So what about the vaccine. We know about the suspended vaccinations in the Philippines where it was concluded that the vaccine could only be given to patients with a laboratory confirmed result of previous infection. With the disease having 4 serotypes and no cross protection (ie contraction of type does not give protection against types 2,3 and 4) then for full protection a patient would need to contract dengue up to 4 times. With the disease showing that it can also produce 2 further conditions of dengue haemorrhaging fever and severe dengue. This is unlike other viruses of the same family such as zika and chikungunya.


With increasingly low air fare costs to infected countries and the only protective advice is the daytime use of insect repellents, is there the risk of a UK traveller returning with dengue increasing?


With the EU licensing the use of dengue vaccine for clinically assessed patients, should the MHRA now be considering the introduction of the vaccine for use in travellers resident in the UK and travelling to endemic areas, such that we have an established set of trial data that will be available should the infection ever mutate and survive in the UK weather conditions.

 

References

1. https//www.ecdc.europa.eu/sites/default/files/documents/RRA-dengue-in-Spain-France_1Oct2019.pdf

2. https//economictimes.indiatimes.com/news/science/dengue-virus-is-becoming-resistant-to-vaccines-and-treatment-study/articleshow/71253957.cms

3. https//wwwnc.cdc.gov/travel/notices/watch/dengue-americas




Rugby World Cup- Japan- conflicting reports.

Posted on 18 September, 2019 at 0:40 Comments comments (0)

With the imminent start of the RWC and the masses of supporters attending Japan I have followed the reports of safe travel measures over the last few weeks.


Whereas we understand the risks from highly contagious diseases such as measles there have been several conflicting reports made contrary to the UK guidance. A former international player was indicating in Wales that Japanese Encephalitis was a disease of risk and vaccinations were available. Whilst encephalitis is a severe medical condition this was comment was made in support of a charity supporting awareness of the condition.

Recently a report on the ISTM page by a Japanese based travel medicine and quarantine doctor again suggested Japanese Encephalitis was indeed a risk and vaccinations should be considered.


As all travel medicine practitioners know an accurate risk assessment is the most credible method of determining the needs of the travellers. So by considering the life style of the average supporter and the disease vector it can be determined that the mosquito will be flying at night when there are no matches and many supporters will be in groups in the local bars and restaurants.


The NaTHNaC factsheet for the disease indicates that predominantly the mosquitoes are found in rural areas, close to standing water and occasionally in cities. They recommend vaccination for travelers in risk areas staying for longer than 4 weeks. This is reflected again in the Green Book. Similar advice is given by the CDC in their Yellow Book, that minimal risk is found in stays of less than a month is urban areas.


Hence confusion stands as media and conflicting medical reports are made. The key message here is that despite the opinions made, the underlying use of insect repellents and physical barriers such as long sleeved clothing and trousers and bed nets.


Rugby World Cup- Japan- conflicting reports.

Posted on 18 September, 2019 at 0:35 Comments comments (0)


 

With the imminent start of the RWC and the masses of supporters attending Japan I have followed the reports of safe travel measures over the last few weeks.

 

Whereas we understand the risks from highly contagious diseases such as measles there have been several conflicting reports made contrary to the UK guidance. A former international player was indicating in Wales that Japanese Encephalitis was a disease of risk and vaccinations were available. Whilst encephalitis is a severe medical condition this was comment was made in support of a charity supporting awareness of the condition.

Recently a report on the ISTM page by a Japanese based travel medicine and quarantine doctor again suggested Japanese Encephalitis was indeed a risk and vaccinations should be considered.

 

As all travel medicine practitioners know an accurate risk assessment is the most credible method of determining the needs of the travellers. So by considering the life style of the average supporter and the disease vector it can be determined that the mosquito will be flying at night when there are no matches and many supporters will be in groups in the local bars and restaurants.

 

The NaTHNaC factsheet for the disease indicates that predominantly the mosquitoes are found in rural areas, close to standing water and occasionally in cities. They recommend vaccination for travelers in risk areas staying for longer than 4 weeks. This is reflected again in the Green Book. Similar advice is given by the CDC in their Yellow Book, that minimal risk is found in stays of less than a month is urban areas.

 

Hence confusion stands as media and conflicting medical reports are made. The key message here is that despite the opinions made, the underlying use of insect repellents and physical barriers such as long sleeved clothing and trousers and bed nets.

Evaluation of remerging infectious diseases- Measles

Posted on 13 April, 2019 at 0:55 Comments comments (0)

The WHO manages and monitors the universal health coverage and over the past year raised concerns with the increasing numbers of outbreaks of diseases once thought to be eradicated in high income countries, re-appearing.


One of the most frequently seen are the reappearance of measles. In the US there have been 387 cases of measles reported up to the end of March and 140 in the UK. The difference to the number of cases and the rapid spread comes from a complex set of issues, but clearly with improved travel opportunities the transmission of infection can be spread far wider than last in the last century and isolated pockets of non-vaccinated travellers in the community then the risk becomes greater.


Already the Australian authorities are reporting measles in children who are too young (8 and 11 months) to receive the protective vaccination course and this is a major concern to practitioners in this very vulnerable group. This is a further reason to support the endorsement of herd immunity within a community than are old enough and able enough to receive the vaccine; protection of those unable to receive it through age or medical condition.


So is measles really as bad as some people make out? A recent publication from Ottawa, Canada is quite clear with the facts. About 1 in 4 people who contract measles will be hospitalised. About 1 in 1000 will develop brain swelling (encephalitis) that may cause brain damage. One or two in 1000 will dies from measles, even with the best care. The text books will list that the incubation period is 10-12 days with the “rash’ appearing after 2-4 days and the patient being infectious 4 days before and after the appearance of the rash.


Therefore in public health terms this is a serious disease from which US reported numbers this year (2019) have already exceeded the total from 2018. Similar data comes from the UK where in 2018the total number of reported cases was 2599, an increase from the previous year of 906 (53.5%).


In the US the level of concern is now so high that one local authorities ban non-vaccinated children from public areas, and the question has to be asked of the psychological impact to an infant or junior school child not being allowed to mix with children of a similar age and their understanding of the parents choice towards non-vaccination.

 

Much has be discussed about vaccine hesitancy and the impact of the mis-information. This will take generations to be removed from the considerations and thinking of many parents. In order to reduce the amount of “choice” some US states and other countries such as Italy have removed the parental right for non-vaccination due to religious or philosophical grounds. The question that some parents raise is how effective this legislation will be? Another study from Baltimore, US has shown that removal of non-medical vaccine exemptions has improved herd immunity.

 

Therefore the conclusion at this point has to be for an improved public health outcome the freedom of right of choice of the individual needs to be removed or least reduced to improve the protection of the community and this is is unlikely to come from parental persuasion but from legal enforcement.

 

Rabies- non-medically trained advice on the Internet

Posted on 1 February, 2019 at 10:20 Comments comments (1)


With the current shortage of supply of rabies vaccine and the recent death in the UK brings around the annual question why do so few travellers consider this as a risk when travelling outside of Europe.


A quick review of online advice provides a wide range of opinions. The true clinicians warn of the dangers and the national guidelines suggest a course of pre-travel exposure vaccinations.


Looking deeper at the sites that many of the younger travellers review produces comments from travel bloggers who suggest in some cases that rabies is not necessary or of a lower risk. They appear to base their claims on the fact that a) they never had it for travelling; b) they never saw any rabies c) the locals informed them there was no rabies or d) the treatment was available within 72hours. On the basis of this limited and biased information they suggest that rabies remains optional and if exposed then local treatment is available. 


The main point of their mis-understanding is that as untrained in clinical advice, they are unaware of the difference in post-exposure treatment (PET) pathways and also the level of risk.


Looking at the level of risk the ISTM produced a paper which looks at the level of risks of diseases. An animal bite with rabies risk is calculated around 1:100 incidence; comparing this to typhoid (1:2800) and hepA (1:9000) puts the level of risk into a different perspective.

Considering the cost of treatment for PET

Pre-travel vaccination course completed - 2 doses of rabies IM, 3 days apart, ave price $30/vial. Total cost $60.


No pre-travel vaccination course- 4 doses of rabies IM, over 21 days, total cost £120. If dog bite (WHO indicates that 90% of cases are from dogs) then RIG is required at an average cost $500 per vial, an average male may require 2 vials. Availability of RIG is commonly questioned and some areas e.g. Bali may require to import this from another country or send the patient to another destination.

 

To answer the points above, just because they have not seen rabies, did not receive it themselves is not a guide to the level of risk at a location. Neither is the advice from the local guides as they may have commercial reasons for tourism. Finally treatment is a global health concern and may not be readily available - causing increased travel costs and itinerary changes.


In conclusion, there needs to be a foil to some of the travel blog sites and bloggers that their interpretation of the risk towards rabies is flawed and a balanced understanding should be suggested.

 

Reference

Steffen R et al. Vaccine-preventable travel health risks: what is the evidence-what are the gaps? Journal of Travel Medicine 2015; volume 22 (issue 1) 1-12.


WHAT IS THE DIFFERENCE BETWEEN PRE AND PROBIOTICS USE IN REDUCTION OF THE INCIDENCE OF TRAVELLERS DIARRHOEA (TD).

Posted on 13 November, 2018 at 9:15 Comments comments (0)

Yet another study crossed my desk the other week discussing the values and virtues of the use of pre and probiotics in the reduction of travellers diarrhoea. As expected there is no further trial or study information available since the last report that changes the view point of the leaders in travel medicine. There remains insufficient study evidence to recommend if this group of products can be effective in the reduction of travellers diarrhoea.


Upon reading these studies and also the ISTM expert opinion I note that pre and probiotics are always reviewed together in the same group. Undertaking a little more work it became clear that pre and pro ad different types of products and therefore should they be considered separately rather than together.


Prebiotics are formed from long chain oligosaccharides that are produced to stimulate the body’s own gut bacteria (microbiota) to produce higher levels of its own protective bacteria. Probiotics formed from external bacterial cultures work by introducing additional bacteria into the human body.


The evidence to support both groups falls short of large scale trials with meta-analysis and therefore neither group can demonstrate a high evidence based benefit. That being said the prebiotic group does have a lead in the development of evidence. There is one particular product which provides a standardised product. This product is the only second generation one and in smaller scale trials has shown to provide a benefit in the reduction of TD when commenced 7 days before travel. This was first evaluate in a trial in 2010 and supported by another one in 2017. However as we know 2 good trials does not constitute enough evidence for a meta-analysis study.


Turning to the probiotics side my paper published earlier this year confirmed the comments that manufacturer claims of added value do not get off the starting blocks as the comparative data does not list the specific names of the bacteria used, and appears to have some bias in the test methods. The former points were raised and considered by the profession body for the industry as needing attention.


In conclusion there is a good reason to judge these 2 groups separately and accept that at least one of them has stronger clinical evidence towards reducing the incidence of TD. However full acceptance can only occur with larger amounts of study data. Therefore he suggestion is that we need to discuss these 2 groups separately as they do not work in the same manner and the prebiotic group seem to have a superior scientific focus in the manner they approach the issue.


Rss_feed