Friday, January 19, 2007
Dusk till Dawn
Dr Dork is planning an overseas jaunt, hopefully in the not too distant future. He is re-acquainting himself with what little he vaguely recalls in the realm of tropical medicine and travel health. The below will likely be part of an ongoing series and is not intended to be definitive, comprehensive or suitable for personal medical advice. To reiterate...real, living patients with real health issues or concerns...should see real, living doctors.
Remember - Dr Dork is wholly a figment of your imagination...
There are around 400 million infections worldwide, annually, as a ballpark estimate.
Between 1 and 2 million estimated deaths annually. That's 3 or so deaths per minute.
Most deaths are in young children.
There has been increasing resistance to antimalarial medications in recent times. Nonetheless, malaria is not only preventable, but eminently treatable.
Risk is greatest in Sub-Saharan Africa. 90% of malarial infections occur here. Mostly, deaths are in young children.
The risk of contracting malaria in SubSaharan Africa is around 1/50 per month of stay for a traveller, if no chemoprophylaxis is taken.
1 in 4000 travellers to high risk areas will die without prophylaxis.
In Australia, there are about 750 cases per year, with an incidence rate of 1.5/1000.
About 10,000 international travellers fall ill with malaria after returning home each year.
This is a drop in the ocean, in regards to the overall public health impact.
There are four different protozoan species causing malaria:
Plasmodium Falciparum (the nasty one that likes to eat your brain)
The latter two like to set up camp in your liver but generally don't kill you.
P.Falciparum is most common on the African continent, P.Vivax in the Americas and Asia.
Transmission is, in essence, via infected blood.
Usually by the bite of an infected female Anopheles mosquito. Dr Dork has no idea why it is only females. This critter is found in most countries in the tropics and subtropics and loves to feed at night - hence "dusk to dawn".
The first step in malarial precautions is trying to stop the blighted little buzzing b*****s from biting you. Repellent with DEET (N,N-diethylmetatoluamide) is most effective, and at 35% strength gives around 10 hours protection. Clothing and bed linen/nets can be impregnated with a contact insecticide such as permethrin. A good spray of an aerosol insecticide before retiring is advisable, especially if rooms aren't adequately screened.
Longsleeved light clothing is preferable - mozzies are attracted to dark colours. Also to strong perfume and cologne. *What's the deal with safari suits, then ?
In summation -
1. Dress like Michael Bolton
2. Lather yourself with a neurotoxic chemical
3. Develop a noisome aroma
There is no vaccine. Not exactly a "Big Pharma" priority.
And, of course, the chemoprophylaxis - ie. preventative antibiotics. Dr Dork doesn't like taking antibiotics if he can avoid it - he tends to be rather prone to side effects, and recalls having a decidedly unpleasant anaphylactic reaction to penicillin when given it as a teenager.
No antibiotic provides 100 % cover.
Taken from a couple of days before entering the malarious area, until 4 weeks after leaving. One 100mg tablet, once a day. Dr Dork likes that aspect - easy to remember. Not an option if up the duff (Dr Dork estimates his gut at 3 months gestation, oh dear) or prone to peptic ulceration or similar problems. About 1 in 25 get oesophagitis, and candidiasis is common. Interestingly, a small proportion develop an alarming propensity to photosensitivity and sunburn. Dr Dork is already ruling out this one for himself - he took doxycycline once before in the middle of summer. The result was amusing for all and sundry.
This is the one that seems to have all the horror stories. The good news is that it is just one 250mg tablet, once a week, for a couple of weeks prior to entering the risk area and for a month after leaving. The bad news is the contraindication in psychiatric illness and cardiac conduction abnormalities. Pretty much rules that out - the Dork is well and truly bonkers, and has a questionable ticker to boot.
Apparently the risk of seizures/psychosis/major depression is generally low (1:10 000) but is potentially much higher in those of us with a history of psychiatric illness. Even those with their heads screwed on correctly have a 10% incidence of minor "neuropsychiatric" sequelae such as insomnia, mild agitation, and weird dreams.
That's two down for Dr Dork...
Bit on the expensive side, but only one 25omg/100mg tablet once a day as with doxycycline. Also need to start only a day or two prior, but can stop just one week after leaving the malarious area. No good in the gestating, but after auscultating his gut throughout this posting Dr Dork is sure no fetal heartbeat is audible. That kicking must have just been last nights souvlaki...
This one needs good kidney function, and Dr Dork got such a good price for one he is pretty confident about the other. Generally pretty well tolerated, apparently, the odd headache or upset gastrointestinal tract. Dr Dork considers his persnickety bowel emotionally labile at the best of times so this won't be a new problem.
A quadruple dose of malarone also serves as emergency self-treatment for a few days if unable to obtain suitable medical care and one becomes unwell with suspected malaria. The Dorkbowel might be miffed if it comes to that, though.
The reason for the continuing antiobiotic use after leaving the area is referred to as terminal prophylaxis, as some malarial strains (especially P.Vivax, P.Ovale) tend to have dormant liver stages.
Furthermore, one needs to keep potential exposure in mind for a year or two after returning from a risk area, it seems - a pyrexia of unknown origin should generally be considered malaria until proven otherwise if you've recently been to a risk area.
What is it like if you actually have malaria? Dr Dork doesn't know. He has never seen a patient with acute malaria. Part of the reason for the death rate in travellers seems to be the vague nature of malarial presentation, and the tremendous potential for variability in incubation.
In extremis, especially with P. Falciparum, there is often anaemia, jaundice, neurological effects...but especially with milder strains it is described as generally a "flu-like" presentation.
Great. Dr Dork will be panicking over every sore throat for a year.
Risk assessment for the Dork itinerary has a lot to do with location and accomodation, it seems. This is to do with the distribution of various strains, which also varies with the time of year, and with regards to the expected degree of exposure to the mosquito culprit - such as whether you're sleeping in a plush hotel with screened windows or on the beach.
Dr Dork is one of those whom, for reasons unknown, seems especially tasty to mosquitos. There are all sorts of theories to do with blood type, various hormonal levels and whatnot - but no hard evidence as to why some have tastier blood according to mosquito connoisseurs.
Maybe Dr Dork should wear one of these.
Posted by Dr Dork