This is the time of year when we reflect on the event of the past year and prepare for what might be coming over the horizon. 2011 was a year of steady progress in the field of infectious diseases, with notable milestones in all of the big three and some game-changing developments for other infections.

The MicroGnome has picked a handful of achievements for this 2011 MicroGnome review that should inspire anyone with an interest in infection. If you have been living under a stone all year, maybe you should try the coffee zone for a less demanding read.

• Malaria: progress made on a malaria vaccine that works

Reporting the preliminary results of a phase three trials of the RTS,S vaccine candidate in neonates and infant groups from seven African countries over 14 months, the authors of a November paper in the New England Journal of Medicine reported a halving of malaria, and a 45% reduction in severe malaria cases. While these effects are far less than routinely used childhood vaccines, they raise hopes for development of a mortality-reducing malaria vaccine.

• Tuberculosis: working out rapid molecular tests for TB in low income countries

Promising early performance studies prompted the World Health Organisation and other donor agencies to equip clinical laboratories in resource-poor countries with rapid molecular screening tests for pulmonary tuberculosis. In a useful review of this application of molecular microbiology, Carlton Evans explains the need for caution in the introduction of this technology to low and middle income countries.

• HIV/AIDS: antiretroviral therapy has a primary preventive effect

There is a growing awareness of the potential for antiretroviral agents in a preventive role. In a mathematical model of the cost effectiveness and impact of different strategies, an international group showed that effective preventive pre-exposure prophylaxis of the uninfected partner could be more effective than commencing ART earlier in the infected partner.

• Septicaemia: MALDI-TOF speeds up bacterial identification in septicaemia

The application of mass spec-based methods for identifying the contents of blood cultures has been gathering pace in Europe for several years, and has started to spread to other parts of the world. While some clinical laboratory directors might have their heads stuck in the sand, there are plenty of pathologists who would give an arm and a leg for equipment that can trim around 24hr or more off the time to identification of bacterial causes of septicaemia. Klein and colleagues are one of many groups working out how to implement this emerging technology in a busy clinical laboratory service.

Influenza: working out why the vaccine had adverse effects

the adverse effects of Australian produced vaccine are thought to have been due to suboptimal virus splitting by a deoxycholate-based procedure. Benefits of vaccination still outweigh the risk of adverse effect.

• Dengue fever: vaccine trials promise improvements in dengue control

A phase three trial of a tetravalent live attenuated vaccine against dengue virus is now under way. Once industrial production of this promising candidate has been established, its efficacy confirmed and administration optimised, it will be of considerable interest to many parts of the tropics where dengue is a substantial burden on the public health.

So what’s in store for 2012, apart from more of the same?

At a guess, it looks like we’re going to drill deeper into severe sepsis, see an expanding series of field studies and continue our peripatetic investigation of tropical infectious diseases. The language of infection series is set for significant expansion in support of teaching and training activities. One outcome of our 2011 MicroGnome Review was to recognise the need for an expanded writing team. The group sends you their best for 2012, and will now pause briefly to welcome in the New Year.

Trouble in paradise

Once again, Bali has been in the news for the wrong reasons. A favoured holiday destination for so many Australians, Bali has now added a sinister new hazard to its growing list of health risks with notification of HIV infection contracted as a result of a holiday visit to a tattoo artist. Australian public health physicians have urged anyone who has recently got a tattoo while on holiday in Bali to have their HIV status checked: trouble in paradise.

The list of recently documented infection risks associated with travel to Bali and neighbouring Indonesian islands includes:

• Dengue, a common and potentially serious viral infection transmitted by mosquito bites. Cases here have almost doubled every year for five years and are mostly associated with international travel, particularly to Bali. There is currently no vaccine and no effective treatment. Control relies on avoiding mosquito bites where the disease is present.
• Gastrointestinal infections due to Salmonella, Campylobacter and E.coli. Around one third of Salmonella cases originate overseas, mostly in Bali where Salmonella Enteritidis is common.
• HIV/AIDS, and other blood borne viruses from contaminated tattoos, but can also arise from unprotected intercourse, recreational injecting drug use and other exposure to contaminated blood or body fluids. Evidence in recent case may point to tattoo but other routes of infection are possible. In recent case causal contribution of tattoo is debatable.
• Legionnaires’ disease connected with hotel air conditioning, spa baths and warm water systems. Recent cases in people staying in Kuta hotel.
• Rabies, from dog and monkey bites. More than 130 local rabies deaths in recent years. Most districts affected. A control programme has caused a fall in numbers of cases, but has not eliminated the disease. Regular reports of tourists unable to obtain or complete post-exposure vaccination in Bali due to inadequate supply. [Read Geographical Magazine's article on the Bali rabies eradication programme]
• Other infections: Japanese encephalitis can occur following mosquito bites in rural areas. Chikungunya is another mosquito-borne viral infection with an unpronounceable name. Leptospirosis can arise following exposure to contaminated inland water. Sexually transmitted infections are common when holiday-makers let their guard down, throw caution to the wind and engage in behaviour they may come to regret soon afterwards.

The current (as of 26-DEC-11) official recommendation is to reconsider travel to Indonesia, but this doesn’t seem to stop large numbers of Australian holiday makers travelling without taking professional advice or specific health precautions. General practitioners and travel medicine specialists have to pick up the pieces when holiday-makers fail to respect the hazards of mass tourism in a developing country. The risks are not the same as those of holiday travel at home. A naive she’ll-be-right approach to international travel in our region is irresponsibly dangerous.

5 key points on fever in international travellers (clinical problem)

• a travel history should be obtained from anyone with a febrile illness
• malaria should be excluded in anyone with a fever who has been in a malaria-endemic area recently
• then consider dengue & other arbovirus infections if there has been mosquito exposure
• do not forget the neglected bacterial tropical infections: enteric fever, leptospirosis, scrub typhus & melioidosis
• do not forget to ask about potential risk for sexually-transmitted infections & HIV/AIDS

Dengue: 5 point summary of highlights, further details in arbovirus module of Tropical Medicine teaching series

• viral infection of humans spread via Culicine mosquitoes
• in rare cases may prove fatal
• clinical features may not distinguish dengue from other infections
• dengue can be acquired in tropical Australia
• no antiviral treatment is effective against dengue

No. Just for once this isn’t about mapping a microbial genome. This is where you can find some disease distribution maps for the infections we’ve already covered on the road to the FACTM pt 1 exam.

Try these out for size, making note of your answers as you go.

Download (PDF, 581.04KB)

The correct answers can be found via these links:

• neglected bacterial infections
• arbovirus infections

Happy hunting.

No, this post has nothing to do with deception, mendacity or plain lying.

This is about the group of mosquitoes that includes Aedes aegypti; that carrier of yellow fever and dengue. A. aegypti has lyre-shaped markings on the upper surface of its thorax, black and white legs and is one of the most successful Culicine mosquitoes. Its close relative, Aedes albopictus, sometimes known as the “Asian tiger mosquito”, has a silver stripe along the length of its thorax. Both are featured in the lecture notes on Culicine mosquitoes, which form a part of the FACTM pt 1 Arbovirus infections.

So there you have it: ‘borne lyre’ is a helpful little mnemonic that links the arthropod borne (arbo-) viruses with the Aedes group, and A.aegypti, in particular.

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It’s time for a bit of variety. Sadly, we need to move on from malaria to deal with other arthropod-borne diseases. Next, it’s the turn of the arbovirus infections, with particular emphasis on the ones that we encounter more often in our own region. Next Tuesday (11th May, 2010) we’re running the arbovirus infection unit in our Clinical Tropical Medicine series. There will be two mini-lectures, the first of which is reproduced here for wider educational use. The second will be  a Medical Entomology module on the arthropod vectors of arbovirus infection.

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