Dictionary of Tropical Medicine

Diphyllobothrium latum

The broad or fish tapeworm of humans and other fish-eating mammals. Also called Dibothriocephalus latum. Infection acquired by eating fish containing the infective plerocercoid (sparganum) larva. May be associated in humans with a megaloblastic (macrocytic) anaemia due to competition for Vitamin B12.

DALY

Disability adjusted life years.

Daughter cyst

A cyst formed by endogenous or exogenous budding from the germinal layer of a hydatid.

Decompression illness (DCI)

An illness suffered by divers when diving too deep, or too long and characterised by nitrogen bubbles forming in the tissues of the body. This may cause a multitude of symptoms although joint pains are those most-commonly encountered. Confusion may be caused in divers that have suffered an Irukandji sting as the symptoms have some similarities. See also, cerebral gas embolism.

DEET

Diethyltoluamide. An effective insect repellant used on the skin.

Definitive or final host

An animal wherein the adult stage of the parasite resides.

Dengue fever

(Syn. Breakbone fever) A flavivirus, dengue virus types 1-4. Transmitted by infected specific Aedes spp mosquitoes. Sudden abrupt onset of high fever, headache, retrobulbar pain and lumbosacral pain. Fever lasts 6-7 days and may be 'saddleback'. Initial symptoms followed by generalised myalgia, bone pain, anorexia, nausea, vomiting and weakness. A transient mottled rash may appear on 1st/2nd day and a second rash appears with resolution of fever - at first on trunk, spreading outward. WCC and platelet count depressed. Mild haemorrhagic phenomena in a few.

Dengue haemorrhagic fever

Usually a second infection with a different serotype of the dengue virus (see dengue fever). A primary infection at a young age is common finding. Age of patient with DHF is often less than 5 years, but young adults may be affected. Severe illness with abnormal vascular permeability, hypovolaemia and abnormal clotting mechanisms. Bleeding into skin or internally. Dengue shock syndrome may also be a complication.

Dermatophyte

Mould fungi belonging to the genera Microsporum, Trichophyton or Epidermophyton. Cause tinea or ringworm.

Diarrhoea

Usually defined as the passage of three or more liquid motions within 24 hours. However, for exclusively breast-fed infants this may not be satisfactory and the definition is usually based upon what the mother considers to be diarrhoea.

Diarrhoeal episode

Conventionally defined as beginning with the first 24-hour period that meets the definition of diarrhoea and ending with the last diarrhoeal day that is followed by at least two consecutive days that do not meet the definition of diarrhoea.

Dick Test

Skin test used to determine the immune status to scarlet fever.

Differentiation

The process of natural change in a cell from simple to complex and performing a particular function.

Dinoflagellates

Tiny organisms related to coral reefs that are responsible for a number of toxins including saxitoxin (paralytic shellfish poisoning) and ciguatoxin (tropical fish poisoning), and also causing red tides or "reef spawn" in tropical waters.

Diphtheria

Disease caused by the exotoxin released by toxigenic strains of Corynebaterium diphtheriae. May present as cutaneous diphtheria (veld sore), nasal diphtheria, or the more severe pharyngeal or laryngeal diphtheria.

Diphtheroids

Non-pathogenic members of the bacterial genus, Corynebacterium. Comprise part of the normal flora of humans and may be occasional opportunistic pathogens.

Dipylidium caninum

The Dog or double-pored tapeworm. Cosmopolitan in dogs. Occasionally infects humans by accidental ingestion of the intermediate host, the dog flea.

Disease

State of dysfunction, subjectively or objectively apparent.

Disinfection

Killing of infectious agents outside the body by chemical or physical means directly applied.1. Concurrent disinfection is the application of disinfective measures as soon as possible after the discharge of infectious material from the body of an infected person, or after the soiling of articles with such infectious discharges. All personal contact with such discharges or articles being prevented prior to such disinfection.2. Terminal disinfection is application of disinfective measures after the patient has been removed by death or to a hospital, or has ceased to be a source of infection, or after isolation practices have been discontinued. Terminal disinfection is rarely practised; terminal cleaning generally suffices along with airing and sunning of rooms, furniture and bedding. It is necessary only for diseases spread by indirect contact; steam sterilisation of bedding was considered desirable after smallpox (now eradicated).

Disseminated

Spread of the disease throughout the body, usually through the blood.

Distal

Description of part of the body that is furthest from the heart.

DNA

Deoxyribonucleic acid. A type of nucleic acid that preserves the information needed by the cell to tell it how to grow and its role in the scheme of things. Genes are made from DNA.

Donovan bodies

Diagnostic stages of granuloma inguinale (Donovanosis).

Donovanosis

Also known as granuloma inguinale. A tropical sexually transmitted disease caused by Calymmatobacterium granulomatis.

Doxycycline

An antibiotic of the tetracycline class also used to suppress malarial parasites and has variable effects against the liver stages of Plasmodium falciparum.

Drop net

A large net on a rigid frame, which is dropped over vegetation to collect specimens of outdoor-resting mosquitoes.

Dwarf tapeworm

Hymenolepis nana, a small cestode of rodents and humans.

Dysentery

Bloody diarrhoea. The classical manifestations are fever, crampy abdominal pain, tenesmus with mucous bloody stool. All of the enteropathogens that have the facility to invade or destroy the intestinal mucosa, especially the colonic mucosa, will have clinical presentation of dysentery. The common organisms are Shigella spp, Salmonella spp, Campylobacter jejuni, Yersinia enterocolitica, Enteroinvasive Escherichia coli (E.I.E.C.), Enterohaemorrhagic Esch. Coli (E.H.E.C.) Entamoeba histolytica.

Dysplasia

Abnormal atypical cellular proliferation, but not yet advanced enough to be called neoplasia. Usually a forerunner to neoplasia.