Dictionary of Tropical Medicine

Haemorrhage

Bleeding; blood loss.

Hair jellyfish

The Australian colloquial term for Cyanea - also known as Lion's Mane in many other countries.

Halofantrine

US Army discovered antimalarial related to mefloquine, used to kill blood parasites, especially in the treatment of severe malaria due to Plasmodium falciparum.

Hantavirus

Also known as Four Corners virus. A rodent virus from the white-footed deer mouse of the USA. Causes severe respiratory disease of humans.

Heat

An effective analgesic for some deeply-injected envenomations including stonefish, stingray and other venomous-spined fish.

Helminths

Round worms, tapeworms and flukes.

Hendra virus

Virus of Flying Foxes (Fruit Bats) in Australia. Can infect horses and humans. Also known as the Equine morbillivirus.

Hepatitis

Inflammation of the liver

Hepatitis viruses

The most common causes of viral hepatitis are those caused by the Hepatitis A, B, C, D, E and G viruses. Hepatitis F virus has been described but is a doubtful entity. Other viruses which can cause hepatitis include the Epstein-Barr Virus, cytomegalovirus, and the Yellow Fever virus.

Herd immunity

A level of immunity found in a community of animals/humans and related to a particular infection to which the community has been exposed.

Herpes simplex virus

Causative virus of genital herpes and herpes labalis or cold sores.

Herpes zoster virus

Causative virus of chicken pox and shingles.

Heterophil antibody

Antibody which reacts with an antigen which has not stimulated its production (i.e. a cross-reacting antibody).

Hexacanth

A larval stage of the tapeworm having six hooks.

Histoplasmosis

A mycotic disease caused by the dimorphic fungi Histoplasma capsulatum and H. duboisei. The former primarily affects the lungs and is acquired by inhalation of spores in bat droppings (often in caves) and the latter affects the skin and is restricted to West Africa.

HIV (Human immunodeficiency virus)

The name of the causative agent of AIDS.

Holoendemic

Perennial transmission of a high degree resulting in a significant immune response in all age groups, particularly in adults.

Hookworm

A parasitic nematode found in the intestines of humans and animals. They are usually transmitted by infection with the third stage filariform larva orally or through the skin. Examples include Ancyclostoma duodenale and Necator americanus. See also associated diseases such as eosinophilic enteritis and cutaneous larva migrans.

Hormone

A chemical produced in the body by endocrine glands and carried in the blood to other organs where the hormone causes processes to change in the target organ. A chemical messenger.

Host

A human or other living animal, including arthropods, affording under natural conditions subsistence or lodgement to an infectious agent. Some protozoa and helminths pass through successive stages in alternate hosts of different species. Hosts in which the parasite attains maturity or passes its sexual stage are primary or definitive hosts; those in which the parasite is in a larval or asexual state are secondary or intermediate hosts

Host preference

The preference of a mosquito (or other parasite or micropredator) for a particular type of host, human or animal. (To be distinguished from simple readiness to feed on a given type of host when no other is available).

Host range

Array of hosts susceptible to infection with an agent.

Hydatid

Larval stage of Echinococcus, generally containing daughter cysts with a large number of protoscolices.

Hydatid sand

Free protoscolices lying inside a hydatid.

Hydroid

A plant-like member of the class Hydrozoa.

Hydrophiidae

The Family name of sea snakes (but not the kraits).

Hydrozoa

The taxonomic class including the plume-like hydroids, hard stinging "corals", small jellyfish with bells (i.e. bell-shaped bodies), and members of the order Siphonophora which may be buoyed up by gaseous floats.

Hyperendemic

Intense, seasonal transmission where the immunity is insufficient to prevent the effect of diseases on all age groups.

Hypersensitivity

Extreme sensitivity to any protein, over and above its normal effect. It usually occurs in certain sensitive people after more than one exposure to the offending protein.

Hypertension

High blood pressure - usually above 150/95mm Hg.

Hypnozoite

The latent liver forms in Plasmodium vivax and P.ovale which give rise to clinical relapses of malaria by invasion of the circulating erythrocytes.The hypnozoites are not eliminated by the usual chemotherapeutic drugs used in the treatment of malaria (chloroquine, quinine etc) and to achieve a radical cure in these relapsing malarias an antirelapse drug must be added to the treatment regime (e.g. primaquine or etaquine/Tefanoquine).

Hypoendemic

Little transmission, effect on general population not important.

Hypotension

Low blood pressure - usually with the diastolic (the lower level) below 60 mm Hg., and sufficient to cause symptoms (eg. dizziness/collapse).

Hypoxia

Low oxygen saturation (levels) in the body.