The London School of Hygiene & Tropical Medicine features a striking Art Deco frieze of gilded bronze animal figures sculpted into its iron balconies, each symbolizing a threat to human health.
These ten animals—mostly insects and arthropods like fleas, mosquitoes, and ticks—are known for living close to humans and thriving on the food and shelter we provide. Eight of them are disease vectors, earning the nickname “gilded vectors of disease,” though the cobra and bedbug are exceptions. The building, opened in 1929 and now Grade II listed, was designed by Verner Owen Rees and Percy Richard Morley Horder, with the frieze attributed to Morley Horder. The sculptures are stylized yet scientifically identifiable, with insects enlarged for visibility and the cobra scaled down. Despite public health campaigns since World War I, these pests remain prevalent today, making LSHTM’s decorative frieze both artistically unique and symbolically enduring.
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THE BODY LOUSE
The body louse (*Pediculus humanus*) is a small, greyish, wingless insect that clings to clothing and bedding using clawed legs, and thrives in overcrowded, unhygienic environments. It feeds on human blood and can transmit serious diseases like typhus, trench fever, and relapsing fever through infected faeces that enter the skin via scratching. Its life cycle includes three developmental stages before reaching adulthood, and it spreads through direct contact or contaminated items. Head lice (*Pediculus capitis*), nearly identical in appearance, live on scalp hair and cause irritation but do not carry disease; their white egg cases, or nits, are often seen during combing.
THE BEDBUG
Bedbugs, classified under the genus *Cimex*, include two species that affect humans: *Cimex lectularius*, found worldwide, and *C. hemipterus*, common in tropical regions. These small, wingless insects are pale brown and turn chestnut after feeding on blood, which they extract using specialized piercing mouthparts. They hide in crevices of beds and furniture during the day and emerge at night to feed, completing their multi-stage life cycle in these habitats. Bedbugs spread through infested second-hand items like mattresses and luggage, causing skin irritation and sometimes severe allergic reactions. Though once believed to transmit disease, it is now known they are not vectors. Despite their nuisance, their presence remains widespread and persistent.
THE TSETSE-FLY
Tsetse-flies, belonging to the genus *Glossina*, include 23 species, with *G. morsitans* and *G. palpalis* known to transmit sleeping sickness. These large, brown-black flies (6–14 mm) have six legs and a prominent forward-pointing proboscis used to pierce skin and suck blood. Both sexes feed exclusively on mammals, locating them through sight and smell, and typically inhabit vegetation in tropical sub-Saharan Africa. Their life cycle is distinctive, producing live larvae that pupate before becoming adults. Tsetse-flies rest with wings folded over their bodies, though the LSHTM sculpture depicts them with wings spread. They are key vectors of *Trypanosoma*, a parasite responsible for human and animal trypanosomiasis.
THE TICK
Ticks of the genus *Ixodes*, part of the hard-bodied tick family Ixodidae, are small arachnids measuring 2–4 mm with flattened bodies and piercing mouthparts designed for blood feeding. They have eight legs and range in color from greyish to red-brown, occurring globally in areas where wild animals serve as hosts. Humans often acquire ticks accidentally while moving through infested habitats, and once attached, ticks embed their mouthparts into the skin for prolonged feeding. Female ticks lay thousands of eggs that develop through a three-stage life cycle before reaching adulthood. Bites from *Ixodes* ticks cause irritation and may transmit pathogens like *Borrelia*, which causes Lyme disease. Other tick species also pose health risks by spreading various infectious diseases.
THE HOUSEFLY
Houseflies (*Musca domestica*), the most common of 70 species in the genus *Musca*, are small grey insects measuring 6–9 mm with a single pair of wings that partially cover their bodies when at rest. Their legs end in sticky pads, allowing them to cling to smooth surfaces like glass and ceilings. Found worldwide, houseflies live closely with humans and feed only on semi-liquid substances, including food, waste, and decaying matter, using specialized mouthparts. Their life cycle includes several stages, with the maggot phase often seen in decomposing food before maturing into flying adults. Flies are hard to catch due to their large, sensitive eyes that detect movement quickly. They pose health risks by mechanically transferring pathogens onto food, often leading to gastrointestinal illnesses such as vomiting and diarrhoea.
THE FLEA
Fleas, classified under the order *Siphonaptera*, are small, brown, wingless insects with narrow bodies and powerful legs that allow them to jump long distances. Of the 2200 known species and subspecies across 220 genera, most live on mammals, while a small percentage inhabit birds. Human-affecting fleas, such as *Pulex irritans*, are typically found in bedding and clothing and feed on blood using sharp mouthparts that pierce the skin. Their life cycle includes multiple developmental stages before adulthood, all occurring within the host’s environment. While flea bites mainly cause irritation, some species like *Xenopsylla cheopis*, the rat flea, are vectors of serious diseases including bubonic plague and murine typhus. Historically, the rat flea played a major role in the Great Plague of London, contributing to widespread fatalities.
THE MOSQUITO, Anopheles
Mosquitoes of the subfamily *Anophelinae*, particularly the genus *Anopheles*, are medically significant due to their role in transmitting malaria, with *Anopheles gambiae* being one of the most dangerous species in Africa. These small, slender insects (3–6 mm) have long legs, narrow wings, and elongated mouthparts; while both sexes feed on sugar, only females suck blood and pose health risks. Mosquitoes are found worldwide and require still water to complete their multi-stage life cycle, with females often active at dawn or dusk, signaled by their distinctive whine. *Anopheles* mosquitoes rest with their bodies angled upward at 45 degrees, a trait depicted in the LSHTM sculpture. When feeding, infected females inject *Plasmodium* parasites into the bloodstream, causing malaria—a deadly disease prevalent in tropical and subtropical regions. Some *Anopheles* species also transmit filariasis, another serious parasitic illness.
THE MOSQUITO, Culex, Aedes
Culicine mosquitoes, classified under the subfamily *Culicinae*, include 38 genera and 2,750 species, with *Aedes* and *Culex* being the most important disease vectors. These small, slender insects (3–6 mm) have elongated mouthparts, narrow wings, and long legs, with only females of certain species feeding on blood. Most Culicinae mosquitoes, though not major vectors, are widespread in northern Europe, Asia, and America and require freshwater for their multi-stage development. Females emit a distinctive whining sound and are quick to escape danger thanks to their keen sensory organs. At rest, they typically hold their bodies parallel to the surface, unlike *Anopheles* mosquitoes. *Aedes* species transmit arboviruses such as dengue, zika, yellow fever, and chikungunya, while *Culex* mosquitoes spread West Nile virus, Japanese encephalitis, and filariasis.
THE RAT
Rats of the genus *Rattus*, including the Black Rat (*Rattus rattus*) and the Brown Rat (*Rattus norvegicus*), are small mammals commonly found near human dwellings. They are nocturnal, highly adaptable, and capable of gnawing through tough materials with their continuously growing incisors. Their rapid reproductive cycle allows females to produce multiple litters annually, often in synchrony within groups, leading to large populations. Historically, rats introduced from Asia caused widespread damage and disease in Europe, notably contributing to plague outbreaks via the rat flea *Xenopsylla cheopis*. Today, they remain significant pests and can transmit diseases like Weil’s disease through contaminated urine. Their proximity to humans continues to pose serious health and sanitation risks.
THE SNAKE
The cobra depicted in the frieze belongs to the genus *Naja*, specifically *Naja naja*, the Indian cobra, a venomous snake native to the Indian subcontinent and parts of Africa. When threatened, it famously raises its head and expands a hood, a defensive posture captured in the sculpture. Adult cobras grow to 1–1.5 meters and inhabit diverse environments such as forests, rice fields, and villages, laying eggs in rat holes with hatchlings ready for independent life. They prey on frogs, rats, and small birds, playing a vital role in controlling rodent populations that damage grain stores. Though highly dangerous due to their potent venom, cobras hold cultural and symbolic significance, especially in India and Africa, where they are both feared and revered. The snake’s association with healing is reflected in the rod of Asclepius, a symbol of medicine still used today by institutions like the WHO, BMA, and LSHTM.
