Acute Mountain Sickness

AMS is the most common type of altitude illness. While it is a relatively benign illness, it can cause major disruptions to travel plans. More importantly, the presence of AMS indicates that acclimatisation is incomplete and that the traveller is at risk of developing life-threatening altitude illness (HACE or HAPE) should they continue to ascend with symptoms. Rate of ascent and height attained are two of the most important risk factors for AMS. Approximately 25 of visitors who ascend rapidly...

Schistosomiasis

There are five species of schistosomes that are mainly responsible for human infection Schistosoma mansoni, S. haematobium, S. japonicum, S. intercalatum and S. mekongi. The areas in which these occur are illustrated in Figure 8.12. The life cycle of the schistosome is complex. Eggs of the parasite are excreted in the faeces or urine of the human host and hatch in fresh water. Emerging miracidia go on to infect species of fresh-water snails (the intermediate host), these species differing for...

Individual Susceptibility

There are wide differences between individuals in their susceptibility. It used to be thought that a person who is prone to sickness in one motion environment is also likely to suffer when exposed to other types of provocative motion, but, as already indicated, experience shows this not to be so. However, susceptibility does appear to be a relatively stable and enduring characteristic of the individual, even though it can be modified by environmental and experimental factors. An attempt was...

Receptivity Adaptability and Retentivity

Receptivity refers to the way in which the individual processes a stimulus within the nervous system. It is suggested that a person who has high receptivity transduces the sensory stimulus more effectively, and that it evokes a more powerful subjective experience than in a person of low receptivity. Hence, according to the mismatch theory, the receptive has a more intense mismatch signal and is therefore more likely to suffer from motion sickness than the nonreceptive when exposed to...

Clinical Features

The bends, more correctly termed decompression illness, are just one of a variety of diving-related disorders. Divers may also drown or suffer hypothermia, despite using breathing apparatus and wearing very effective thermal protection. Drowning and hypothermia are, however, hazards common to all water sports and as such will not be dealt with in this section. Diving-related disorders can be divided into two major categories conditions that do not require recompression therapy, and those that...

Shipboard Maladies

Although the types of illness and injury encountered aboard a cruise ship are similar to those seen at shore-side outpatient clinics, there are certain medical problems that many people associate with ocean travel or that pose particular diagnostic and therapeutic dilemmas when they arise on board a ship. It is important for the ship's medical staff to be familiar with the common illnesses and injuries that that are seen aboard ship and be prepared to treat and stabilize patients with...

Spider Bites

As with scorpions and many snakes, the harmfulness of a spider cannot be judged from its appearance many of the large brown fearsome tarantula-like spiders are harmless to humans. Perhaps the most dangerous are the black widow spiders of the genus Latrodectus, which are found in most tropical and subtropical countries including North America, Argentina, the Mediterranean region, Middle East, southern Russia, Arabia, Ethiopia, southern and eastern Africa, Madagascar, south and Southeast Asia and...

Alcohol

It is known that alcohol induces nystagmus. Positional alcohol nystagmus appears in two phases. The first appears within 30 min of alcohol intake and shows nystagmus, with the fast component beating to the right if the subject is in the right lateral position and vice versa. This phase lasts about 3-4 h and is followed by an intermediate period in which no nystagmus is observed. The second phase begins 5-6 h after the consumption of alcohol and the direction of movement is reversed, in that the...

Trapped Gas Dysbarism

The body cavities that contain gas are as follows Middle ear. Many air travellers are familiar with what happens when they cannot clear their ears as a result of a common cold. The mechanism of this disturbance, known as otic barotrauma, may be explained as follows. The eustachian tube connects the middle-ear cavity with the nose. It permits the passage of air in and out of the middle-ear cavity, thus preventing distortion of the eardrum during changes in ambient pressure. The normal state of...