[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Arthropod vectors](https://durgical.com/en/microbiology/groups/arthropod-vectors/) › Culex and Mansonia

# Culex and Mansonia

- Parasite
- Exam priority: medium

Brown night-biting mosquitoes. Culex breeds in dirty standing water and carries West Nile virus and filariasis; Mansonia breeds among water plants.

Updated Nov 13, 2026

Also called: house mosquito (Culex quinquefasciatus), southern house mosquito, zancudo

## Quick facts

**Type**
Parasite · [Arthropod vectors](https://durgical.com/en/microbiology/groups/arthropod-vectors/)

**Gram / shape**
Plain brown mosquito that rests

**Spread**
Only the female bites · West Nile and similar viruses

**Causes**
Lymphatic filariasis · West Nile virus disease

**Treatment**
Does not apply to the insect

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Life cycle
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Culex: egg rafts, polluted standing water, bites from dusk to dawn.
- Culex quinquefasciatus: main urban vector of Wuchereria bancrofti.
- West Nile: bird reservoir, Culex vector, humans and horses are dead-end hosts.
- Mansonia larvae breathe from water-plant roots; carries Brugia.
- Control: sanitation and removing standing water, plus nets.

## At a glance

**Shape**
Plain brown mosquito that rests with its body parallel to the surface; Mansonia has speckled wing scales and banded legs

**Family**
Culicidae, subfamily Culicinae

**Type**
Blood-feeding dipteran insects (biological vectors)

**Size**
Adult a few millimetres long

## Morphology

- Culex eggs are stuck together in floating rafts; Mansonia eggs are laid in clusters under floating leaves.
- Culex larvae hang from the surface by a long breathing siphon.
- Mansonia larvae and pupae pierce the roots and stems of water plants with a saw-like siphon to take air, so they rarely surface.

## Transmission

- Only the female bites; Culex is most active from dusk to dawn, inside and outside houses.
- West Nile and similar viruses: the mosquito is infected by biting birds, then bites people and horses (dead-end hosts).
- Filariasis: microfilariae taken in a blood meal become infective L3 larvae in the mosquito and enter the skin at a later bite.
- Mansonia bites aggressively at dusk near swamps and lakes with floating vegetation.

**Reservoir:** Birds (West Nile and related encephalitis viruses); Humans with circulating microfilariae (Wuchereria bancrofti); Wild rodents and other animals for some encephalitis viruses

**Vector:** Culex quinquefasciatus is the main urban vector of Wuchereria bancrofti worldwide and, with other Culex, of West Nile and Japanese encephalitis viruses; Mansonia carries Brugia filariasis in Asia and also W. bancrofti.

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- Culex females lay rafts of 100–300 eggs on still water; Mansonia lays egg clusters under floating plants.
- Culex breeds in ponds, drains, septic tanks, latrines, unused pools and containers, including polluted water.
- Larvae (wigglers) feed in the water and moult four times.
- The non-feeding pupa lives just below the surface (or attached to plants in Mansonia); the adult emerges from it.
- Egg to adult takes about one to two weeks in warm weather.
- Adults rest by day in cool, dark, humid places and usually fly short distances.

## Virulence factors

- Breeding in polluted water makes Culex thrive in poor urban sanitation.
- Culex feeds on both birds and mammals, bridging bird viruses to people and horses.
- Night biting overlaps with sleep, so nets and screens help.
- Resistance to insecticides is common in Culex quinquefasciatus.

## Diseases it causes

- Lymphatic filariasis (Wuchereria bancrofti; Brugia with Mansonia) [Lymphatic filariasis →](https://durgical.com/en/conditions/lymphatic-filariasis/)
- West Nile virus disease and other mosquito-borne encephalitis (Japanese, St Louis) [Viral encephalitis (herpes simplex encephalitis) →](https://durgical.com/en/conditions/viral-encephalitis/)
- Nuisance bites and papular urticaria

## Clinical picture

- Itchy night-time bites; in children, papular urticaria.
- West Nile: most infections cause no symptoms; a few cause fever and a small number meningitis or encephalitis.
- Lymphatic filariasis: lymphoedema, hydrocele and elephantiasis years after infection.

## Diagnosis

- Entomology: larvae by siphon and body hairs, adults by wing scales and resting posture.
- Testing mosquito pools for West Nile virus as an early warning of human cases.
- Patient: filarial antigen tests or night blood smears for W. bancrofti; IgM antibodies in serum or cerebrospinal fluid for West Nile.

## Treatment

Does not apply to the insect. West Nile has no specific antiviral (supportive care); filariasis is treated and prevented with albendazole, diethylcarbamazine and ivermectin in mass drug administration.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Albendazole](https://durgical.com/en/pharmacology/albendazole/)
- [Diethylcarbamazine](https://durgical.com/en/pharmacology/diethylcarbamazine/)
- [Ivermectin](https://durgical.com/en/pharmacology/ivermectin/)

## Prevention

- Drain, fill or treat standing water: blocked drains, septic tanks, latrines and unused pools.
- Bed nets, window screens and repellents from dusk to dawn.
- Removing floating water plants from ponds and channels to control Mansonia.
- Mosquito and bird surveillance for West Nile; mass drug administration against filariasis.

## Memory aid

Culex likes the dirty drain and the night shift; Mansonia hides under the water lily and breathes through its roots.

## Test yourself

Think of the answer, then tap the question to see it.

## Where does Culex quinquefasciatus prefer to breed?

In still, often polluted water: drains, septic tanks, latrines, ponds and neglected pools.

## Why are humans called dead-end hosts of West Nile virus?

Because the virus does not reach high enough levels in human blood to infect new mosquitoes; birds maintain the cycle.

## How do Mansonia larvae breathe?

They insert their siphon into the roots or stems of water plants and take air from them, so they rarely come to the surface.

## Which filarial worm does Culex quinquefasciatus transmit in cities?

Wuchereria bancrofti, the main cause of lymphatic filariasis.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/culex-and-mansonia/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 6

- [Wuchereria bancrofti / Brugia malayi](https://durgical.com/en/microbiology/wuchereria-bancrofti-brugia-malayi/)
- [West Nile virus](https://durgical.com/en/microbiology/west-nile-virus/)
- [Japanese, St. Louis and tick-borne encephalitis viruses](https://durgical.com/en/microbiology/japanese-st-louis-and-tick-borne-encephalitis-viruses/)
- [Equine encephalitis viruses and Mayaro virus](https://durgical.com/en/microbiology/equine-encephalitis-viruses-and-mayaro-virus/)
- [Aedes aegypti and Aedes albopictus](https://durgical.com/en/microbiology/aedes-aegypti-and-aedes-albopictus/)
- [Anopheles](https://durgical.com/en/microbiology/anopheles/)

## Related conditions 2

- [Lymphatic filariasis](https://durgical.com/en/conditions/lymphatic-filariasis/)
- [Viral encephalitis (herpes simplex encephalitis)](https://durgical.com/en/conditions/viral-encephalitis/)

[← Back to the group: Arthropod vectors](https://durgical.com/en/microbiology/groups/arthropod-vectors/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [About Culex Mosquitoes | Mosquitoes | CDC](https://www.cdc.gov/mosquitoes/about/life-cycle-of-culex-mosquitoes.html) (CDC, 2024); [About West Nile | West Nile Virus | CDC](https://www.cdc.gov/west-nile-virus/about/index.html) (CDC, 2025); [CDC - DPDx - Lymphatic Filariasis](https://www.cdc.gov/dpdx/lymphaticfilariasis/index.html) (CDC, 2024); [Lymphatic filariasis](https://www.who.int/news-room/fact-sheets/detail/lymphatic-filariasis) (WHO, 2025).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/culex-and-mansonia/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/culex-and-mansonia/