Q: A patient is going to West Africa with work for several weeks. Can he take atovaquone plus proguanil for more than 28 days as prophylaxis? And what would you recommend as emergency treatment?
A: Atovaquone plus proguanil is currently licensed for use as malaria prophylaxis for 28 days only because there is not yet enough data on long-term use. However, after obtaining specialist advice, it is probably reasonable to prescribe it for up to three months in healthy individuals.
Atovaquone plus proguanil is of particular value to travellers exposed to the risk of malaria for a short period. It should be taken for one or two days before going into a malarious area, continued throughout the visit, and then taken for seven days after leaving the area.
West Africa is an area with chloroquine resistance, therefore the most appropriate emergency treatment would be quinine with doxycycline. This is administered as two 300mg tablets of quinine three times a day for three days, and one tablet of doxycycline 100mg daily for seven days.
Other drugs that could be considered for use include mefloquine and co-artemether.
Quinine can be given IV if the person is seriously ill and unable to take tablets.
Atovaquone plus proguanil is the first line of emergency treatment, followed by co-artemether which is followed by quinine and doxcycline.
- Dr Jane Zuckerman, director of the Academic Centre for Travel Medicine and Vaccines
Q: When doing investigations to check the LFTs on patients on statins there are often rises in GGT but not other abnormalities. At what level in asymptomatic patients should we investigate further and what tests should be done?
A: The general advice on statins and the liver concern the behaviour of the transaminases, ALT and AST.
If these rise to greater than three times the upper limit of normal for your laboratory, then the statin should be withdrawn. It seems that LFTs almost invariably return to normal thereafter.
Smaller rises in transaminases appearing shortly after the initiation of treatment often return to normal with continuing statin use.
Thus, if you find an isolated elevation in GGT with other LFTs being normal, then no action is required. Always consider other possible causes of a raised GGT, such as a hectic social life. Statins should be used cautiously in patients with a history of excessive alcohol consumption.
Dr Andrew L Clark, reader and honorary consultant cardiologist, Castle Hill Hospital, Cottingham
Q: What evidence is there on the pros and cons of the available antenatal tests for Down's syndrome? Which are most sensitive, and what are the possible problems?
A: The only definitive test for Down's syndrome is a karyotype, taken after an invasive procedure such as amniocentesis (which has a 1 per cent fetal loss rate, or chorionic villous sampling (2 per cent loss rate).
If a woman cannot cope with uncertainty, has a particular fear or past history, or has a high risk from screening and she does not mind the complications, she should consider invasive testing.
Most units offer some type of screening programme before invasive testing is done. This minimises unnecessary testing and fetal loss, and maximises the diagnosis of Down's syndrome so that parents can prepare for the birth or consider termination. Traditionally maternal age alone as an indicator was used for screening, but this picked up only 30 per cent of cases.
Women are now usually offered a screening test (which takes age into consideration). Many units offer a second-trimester serum screen (with a variety of numbers of analytes) which picks up about 70 per cent of cases. As long as there is a dating scan, serum screening is reliable and cheap, although it is difficult to administer.
Increasingly, nuchal scanning is offered, where the translucent area at the back of the fetal neck is measured. Risk is then calculated using a formula that includes maternal age. This can pick up 80 per cent of Down's syndrome cases, as well as other non-viable trisomies and cardiac anomalies.
Further refinements of the tests are being included, and include combinations of serum and nuchal, integration of first- and second-trimester results.
Purported benefits of first-trimester screening include earlier termination or reassurance. However, there are concerns that screening might be picking up inevitable losses rather than reducing Down's syndrome births, and that an early focus on abnormality might distort the positive experience of pregnancy.
Finally, anomaly scanning at 18-20 weeks can pick up very minor findings that change the background likelihood of a chromosome anomaly (for example renal pelvic dilatation, choroids plexus cyst, or echogenic foci in the heart). These can cause anxiety for women.
More research is needed on genuine risks and benefits of all the tests, and there is still no national agreed consensus on the best method of screening.
Women should be advised not to have multiple screens as this increases the false-positive rate without corresponding benefit. They should also be clear about the purpose of screening, and be counselled in advance about the chance of a positive test, and how they might react.
Women who do not wish to have screening and would not consider termination in any circumstance should have their views respected, but still be offered scans for the purposes of dating, growth and placental localisation.
- Dr Susan Bewley, consultant in obstetrics/maternal-fetal medicine at Guy's and St Thomas' NHS Foundation Trust, London.