MCQs in Travel Medicine by Colbert Dom;

Author:Colbert, Dom;
Language: eng
Format: epub
Publisher: Oxford University Press, Incorporated
Published: 2013-08-15T00:00:00+00:00

chapter 10

SPECIAL ACTIVITIES

ANSWERS

Swimming

1. A. Approximately 75% of drownings occur in fresh water and 25% in the sea. Freshwater drowning can occur in a few minutes. In these cases the blood volume may increase by as much as 50% in 3 minutes due to the osmotic passage of water across the pulmonary alveolar/capillary membrane. Pulmonary oedema occurs in saltwater drowning and death is slower. In both cases hypoxaemia, acidosis, and unconsciousness ensue.

Dry asphyxia occurs in up to 20% of cases, with laryngeal spasm preventing the entry of water into the bronchial tree. Up to 25% of those resuscitated immediately after near-drowning die within 24 hours, so-called ‘secondary drowning’.

Drowning is an added danger for the holidaymaker who swims in an unknown or isolated location where currents, alcohol, inexperience, and lack of help become major contributory factors. Drowning is the third most common cause of death in children in the USA after road traffic accidents and burns. Note: hypothermia is an important factor in drowning at sea.

2. C. Climb-resistant pool fencing and self-closing gates have been proved to reduce the danger of drowning in children.

Pool covers and alarms are often out of order, usually children drown silently, often when the supervisor is momentarily distracted. Immediate CPR is of help but the outcome is not improved after transfer to an ICU. Neither personal flotation devices nor inflatable life vests appear to reduce the incidence of drowning in those <14 years of age.

3. D. It is said that conjunctival suffusion and myalgia are pathognomonic of Leptospirosis, both of which were present in the above case. Leptospires are highly motile spirochetes harboured in the kidneys of many wild and domestic animals. They are shed continually in the urine. Humans are infected through skin abrasions or mucus membranes contacting infected freshwater. The disease is on the increase and is often reported in travellers who take part in water sports.

Icteric leptospirosis (Weil’s disease) occurs in 5-10% of all cases. This has a high mortality if untreated. However, leptospirosis is mostly asymptomatic. Inexplicably it appears to be a milder condition in women.

Malaria is more or less confined to south-west China, especially Hainan, where P. falciparum occurs. Otherwise any malaria found is the ‘benign form’. Dengue fever is common in China and must be excluded despite the fact that he says he got no bites.

Legionnaire’s disease is a possibility but pulmonary symptoms are usually prominent.

4. A. N. fowleri is a free-living thermophilic amoeba-type organism found globally in warm fresh waters such as hot springs, spas, untreated swimming pools, ponds, lakes, and sewage. It is found in three forms: as a cyst, as a trophozoite (amoeboid), and as a biflagellate.

The trophozoites thrive between 30 and 46°C and enter the cranium via the cribriform plate. This ensures that the trophozoites are more likely to affect children in whom the cribriform plate is thinner than in adults. When the temperature falls the trophozoites revert to thick-walled cysts, which are still infective as a dust aerosol. These inactive cysts revert to infective trophozoites once the temperature rises again.

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