Dictionary of Tropical Medicine

Salivary glands

The glands that produce the saliva injected when a mosquito or other ectoparasite bites, which prevent blood from clotting while the mosquito feeds.

Salpingitis

Inflammation of the fallopian tubes.

Sarcoma

A cancer of connective tissue, bone, cartilage, fat, muscle, nerve sheath, blood vessels or lymph system.

Scabies

A parasitic skin diseases caused by the mite, Sarcoptes scabiei, presenting often as intensely itchy papules, vesicles, or tiny linear burrows containing scabies mites and their eggs. Lesions are often found around finger webs, skin folds and flexures, the abdominal region and external genitalia (especially in men). Often associated with a rash on the body, but usually sparing the face.

Schistosomiasis

A disease caused by parasites of the genus Schistosoma, also known as bilharzia, which has an aquatic snail intermediate host.

Schizonts

Stage in the life cycle of opicomplexan protozoa in which there is multiple asexual divisions (e.g. in malarial parasites).

Scolex

The anterior organ of a tapeworm used for attachment to host tissues. Also known as the holdfast.

Scorpaenidae

Family name for a group of fish (including the stonefish) having venomous spines which may cause severe local pain. Heat is usually an effective analgesic for this more deeply-seated pain.

Scorpionfish

See Scorpaenidae.

Scrub typhus

A febrile illness caused by Orientia tsutsugamushi, transmitted through the larval stage of several species of infected trombiculid mites, often called chiggers. The endemic region is a roughly triangular area bounded by Japan in the north, Pakistan in the west and with Queensland, Vanuatu and the Solomon Islands in the South.

SCUBA

Self-contained underwater breathing apparatus.

Scurvey

A diseases resulting from vitamin C deficiency.

Scyphozoa

The taxonomic Class for most jellyfish except the cubozoans.

Sea lice

A colloquial term used for any creature, or anything present in sea water causing a mild irritation of the skin, either with or without a rash. There is no single creature responsible for this stinging effect.

Sea nettle

Colloquial term for the north American jellyfish Chrysaora quinquecirrha.

Sea snakes

Marine, air breathing reptiles with a potent neurotoxic and myotoxic venom responsible for many deaths world-wide - although there are no documented deaths in Australia. They are usually found close to shore, or on coral reefs. They are easily distinguished from land snakes by their wide, flattened tail which is used for swimming, and from eels by their lack of gills. Fortunately, despite having a potent venom, when they bite they inject venom in only some 20% of cases.

Sea urchins

Creatures with needle-sharp spines that are present on rocks or reefs. They cause simple, but painful puncture wounds with spines frequently breaking off in the wounds which leads to infection. Some species also produce toxins that may cause severe localised pain or other systemic symptoms.

Seasonal prevalence

The number of cases of infection in relation to the unit of population in which they occur (a static measure) at different times of the year.

Secondary attack

A measure of the occurrence of a contagious disease among known (or presumed) susceptible persons following exposure to a primary case.

Secondary cancer

A cancer that originally started somewhere else in the body, but is now growing at another site. A metastasis.

Semaeostomeae

The taxonomic order of scalloped jellyfish.

Semelparous

Giving birth only once.

Seminal receptacle

A dilated organ in the female genital tract of cestodes which stores sperms.

Seminal vesicle

The dilated lower part of the vas deferens of cestodes which opens into cirrus.

Sensitivity

The probability that the test will be positive when infection is present.

Septicaemia

The presence of multiplying bacteria in the bllod associated with severe clinical symptoms.

Serpinigerous

A lesion which takes on a winding tunnel-like appearance (eg in cutaneous larva migrans and the larva currens rash).

Serum sickness

A complex systemic reaction that may become evident any time up to 14 days after antivenom or antitoxin use. Symptoms are fever, generalised lymphadenopathy and an urticarial rash. Severe cases of serum sickness may have to be treated with oral steroids. The incidence of serum sickness is often related to the amount of antivenom used.

Shock

Collapse of the circulation resulting in inadequate tissue perfusion to the body cells.

Side effects

Unwanted effects of a drug or treatment.

Sign

An indication of the existence of something; any objective evidence of a disease.

Simuliid

A family of biting flies commonly called blackflies including the important Simulium, sometimes vectors of onchocerciasis.

Siphonaptera

(Aphaniptera) Order of jumping and blood-sucking, wingless (apterous) insects known as fleas.

Siphonophora

The taxonomic group of hydroids that are not single animals, but colonies of animals. They may be either free swimming or floating, with or without a float. The genus of dominating medical importance is Physalia.

Sleeping Sickness

A disease caused by haemoflagellate protozoa and transmitted by blood-feeding tsetse flies of the genus Glossina. East African (Rhodesian) Sleeping Sickness is the more severe zoonotic form caused by Trypanosoma brucei rhodesiense found on the game-rich savannahs of East Central Africa while West African (Gambian) Sleeping Sickness is the more chronic form found in riverine areas of West Central Africa and which has a significant human reservoir although animals such as pigs may also be involved as reservoirs.

Slow virus

See prion.

Smallpox

Variola. A human viral disease characterised by vesicular skin lesions covering the whole body but being particularly heavy at the extremeties including the face. Caused by a pox virus. The disease can be prevented through regular smallpox vaccinations. Variola has now been officially declared eradicated by the WHO.

Snottie

A colloquial term for Cyanea. Also known as the Lion's mane and Hair jellyfish.

Somatic

Of the body.

Source of infection

The person, animal, object or substance from which an infectious agent passes immediately to a host. Source of infection should be clearly distinguished from source of contamination, such as overflow of septic tank contaminating a water supply, or an infected cook contaminating a salad.

Species

A fairly well-defined, interbreeding group of plants or animals. The lowest taxonomic grouping of closely-related varieties - below a Genus. See Taxonomy.

Specificity

The probability that the test will be negative when the infection is not present.

Spicule

A male accessory reproductive organ in nematodes helping to attach the male to the female during copulation. There may be one or two or it may be absent in some nematodes.

Spiruroid

A two-parted oesophagus - anterior muscular and posterior glandular structure as in most of Spiruroidea and Filarioidea.

Sporozoite rate

The proportion of female mosquitoes that have sporozoites in the salivary gland.

Sporozoites

The final stage of development of Plasmodium in the mosquito; this is the infective form of the malarial parasite; occurring either in a mature oocyst before its rupture or in the salivary gland of a mosquito.

SPR

Slide Positivity Rate is obtained by dividing positive blood slides by total slides examined.

Spread

The way a neoplasm increases in size or invades the body.

Squamous Cell Carcinoma

Malignant tumour of squamous epithelium of skin, which generally spreads and metastasises.

Stage

Estimate of the extent of spread of a cancer; usually expressed in as a number, often with subdivisions. The prognosis of a particular cancer varies with the staging.

Statocyst

A jellyfish balance organ, usually consisting of a calcium or magnesium carbonate crystal, the movement of which against surrounding cilia enables the medusa to determine its position in the water.

Stichosome

A long, slender oesophagus embedded in rows of emboidal oesophageal gland cells as in Trichinelloidea.

Sting

The painful injection of a venom through skin or mucous membranes of a victim. Cf. bite and envenomation.

Stingers

A colloquial term to be avoided. In tropical Australia the term usually refers to the lethal box-jellyfish Chironex fleckeri, whereas in the rest of Australia it may refer to any stinging jellyfish which are non-lethal.

Stingose

20% aluminium sulphate solution - useful for itching caused by some insect stings, but less effective (or ineffective) for the skin pain of jellyfish envenomations.

Stingray

A group of fish with flattened fins making it look saucer-shaped. It has a long tail with at least 1 and up to 7 venomous spines. When stimulated the tail may flick across, either embedding the barb in the victim, or causing a severe laceration. Eight deaths (2 in Australia) have occurred world-wide, either from blood loss, venom effects or tetanus.

Stomolophus

Usually an innocuous genus of jellyfish represented by Stomolophus meleagris world-wide. However, in areas of East China around Behoe, on the East China Sea, there have now been 8 reported deaths from a rare species called S. numerai.

Stonefish

Synanceja sp. - a fish which can camouflage itself, changing its colour to match the background. It remains motionless on the bottom where the unwary victim can tread on it. There are 13 venomous dorsal spines on its back which can penetrate even thin-soled shoes, injecting a venom that causes severe localised pain. The pain is best relieved by the application of heat. No deaths have occurred in Australia; 2 poorly-documented deaths have occurred in other countries.

Strobila

The body of a tapeworm.

Strobilisation

The process of producing or growing new segments (proglottids). This happens near the neck region. A form of asexual reproduction in some cubozoan jellyfish by which miniature medusa-like structures are formed, often one on top of the other, resembling stacked dinner plates.

Strongyliform

A short buccal muscular structure with waist found in nematodes, such as Ancylostomatidae.

Subclinical infection

Without clinical manifestations: said of the early stages of, or slight degree of, an infection.

Subumbrella

The area of a jellyfish under the bell.

Surveillance

The monitoring of changes in the numbers of mosquitoes or disease cases over a period of time.

Surveillance of disease

As distinct from surveillance of persons, surveillance of disease is the continuing scrutiny of all aspects of occurrences and spread of a disease that are pertinent to effective control. Included are the systematic collection and evaluation of:1. morbidity and mortality reports;2. special reports of field investigations, of epidemics and of individual cases;3. isolation and identification of infectious agents by laboratories;4. data concerning the availability and use of vaccines and toxoids, immunoglobulin, insecticides, and other substances used in control;5. information regarding immunity levels in segments of the population; and6. other relevant epidemiological data.

Susceptible

Prone to infection by parasites and pathogens. A person or animal presumably not possessing sufficient resistance against a particular pathogenic agent and for that reason liable to contact a disease if or when exposed to the disease agent.

Swollen Belly Syndrome

A condition seen in very young children in Papua New Guinea infected with a Strongyloides flleborni-like species of intestinal nematode.

Symbiotic

A close relationship between two species which usually works to the advantage of both.

Symptom

Any functional evidence or disease or of a patient's condition; a change in a patient's condition indicative of some bodily or mental state.

Syndrome

A pattern of symptoms and signs, appearing one by one or simultaneously, that together characterise a particular disease or disorder.

Syphilis

A sexually transmitted disease caused by Treponema pallidum. A non-venereal, form, known as treponarid (or by such local names a bejel or Njovera) is caused by T. endemicum and is clinically very similar to yaws.

Systemic

Involving the whole body or organism, and not just individual parts.