Entomology

Fleas, Lice, Mites, Mosquitoes, Ticks

Looking for lice A daily business …

Courtesy CDC

Pediculus spp.

Rickettsia prowazekii: epidemic typhusBartonella quintana: trench fever

Borrelia recurrentis: epidemic relapsing fever

Sam R. Telford III. 2007. In ASM Manual of C.M.

Evidence for Louse-transmitted diseases in soldiers of Napoleon’s Grand Army in Vilnius (Lithuania)

PCR of dental pulp from the remains and lice in earth from the grave revealed DNA of Bartonella quintana and Rickettsiaprowazekii in nearly one third of the buried soldiers.

Raoult D. et al. 2006. JID. 193:112-120.

Rickettsia prowazekii• The Polish Partisan Alec Ossowski

was a prisoner in Auschwitz. • …• There was a Hungarian Jew who

was ill with typhoid, so he scooped the lice from under his arm and put them inside the coat of the nasty SS-doctor. The doctor got the disease and died.

De Standaard. 27 januari 2005.

Pediculus sp. Nit of head louse attached to hair shaft.

Pediculus humanus var. corporis Human body louse. Nymphal-staged lice and adults.

Courtesy CDC

Pediculus capitis Head of the head louse.

Phthirus pubis Crab louse from pubic hair.

Jigger (chigger) flea Typical lesion on a toe caused by the female flea

Tunga penetrans.

Courtesy Peters & Gilles H.M.

Tunga penetrans Small flea, present in tropical areas.

Tunga penetrans Large egg seen in a skin lesion.

Xenopsylla cheopis (right)The oriental rat flea is the primary vector of the

agent of plague, Yersinia pestis.

Courtesy CDC

Sarcoptes scabiei The adult itch mite is very small.

Norwegian scabies

Norwegian scabies is an extremely infectious condition, since tens of thousands of mites are present in the hyperkeratotic skin and squames of the patients. Early diagnosis of Norwegian scabies is thus crucial for therapeutic and infection control purposes.

Wong S. et al. 2005. JCM 43:2542-2544.

Demodex folliculorumFound in the follicles of simple hairs.

Courtesy K-State

Dermatobia hominis This myasis is acquired in a curious manner. The eggs

are transported by various bloodsucking insects (such as mosquitoes).

Courtesy Goddard JCourtesy Goddard J

Dermatobia hominis The human bot fly is widely distributed in Central and

South America, and in parts of Mexico. The larva occurs in diverse animals.

Courtesy Goddard JCourtesy Goddard J

Dermatobia hominis Second stage larva with a curious appearance known

as ver macaque (macaw worm, tropical warble fly).

Dermatobia hominis Third stage larva called torcel or berne.

Dermatobia hominis

Courtesy Mehrany M.

Cordylobia anthropophaga Produces a furuncular type of myasis in Tropical Africa. Children are commonly affected. The lesions

occur on areas normally covered with clothing.

Courtesy Goddard JCourtesy Goddard J

Tsetse fly: Glossina spp.

• Male and female are haematophagous.

• Feed on man and animals (pig, antelope...)

Courtesy Tulane

Glossina spp. Tse-tse

Ixodes

Borrelia burgdorferi: Lyme diseaseEhrlichia chaffeensis: human monocytic

ehrlichiosisAnaplasma phagocytophilum: anaplasmosis

Rickettsia conorii: boutonneuse feverBabesia spp.: babesiosis

Sam R. Telford III. 2007. In ASM Manual of C.M.

Amblyomma americanum The American lone star tick.

Courtesy Iowa State University EntomologyCourtesy Iowa State University Entomology

Ixodes ricinus Thicks are obligate, blood-sucking ectoparasites of

many animals and man. This species is the vector of Lyme-disease in Europe.

1 cm

Ixodes ricinus Female thick with four pairs of legs.

Triatoma infestans South American “kissing bug” vector for

Trypanosoma cruzi, the agent of Chagas disease.

Courtesy CDCCourtesy CDC

Phlebotomus sp. Female sandfly, a vector of the parasite responsible for

Leishmaniasis.

Courtesy CDCCourtesy CDC

Sand fly

• Tiny (3mm long).• Live in caves, cavities,

tree holes …• Female: blood feeder.• Active at night (little

or no wind).• Phlebotomus spp.

Courtesy CDC

Occasional presence of Phlebotomus sp. in the Belgian Ardennes.

Ripert C. 2007. Epidémiologiedes maladies parasitaires 4.

Mosquitoes: basic biologyMosquitoes: basic biology

• Larvae and pupae always found in water.• Adult mosquitoes of both sexes feed on

nectar.• Females of most species need a blood meal

for egg development.• In temperate climate: diapause (adults in

dormant state) or produce dormant eggs.

Mosquitoes: basic biology II

• Three major breeding groups:

– Permanent water breeders: Anopheles and many Culex in swamps, ponds, lakes, and ditches.

– Floodwater breeders: salt marsh, inland flood water, and rice field mosquitoes.

– Artificial container/tree hole breeders: Aedes aegypti and Aedes albopictus.

Courtesy US Navy Medical Department

Courtesy US Navy Medical Department

Mosquitoes as vectors

• Aedes: filaria, viruses (e.g. Aedes aegypti for dengue and yellow fever).

• Anopheles: malaria, filaria (Wuchereria bancrofti) , viruses.

• Culex: filaria, viruses (e.g. Culex pipiens for SLE).

Aedes aegypti• Worldwide within the

20°C isotherms.

• Vector of yellow fever and dengue.

• Urban mosquito.

• Daytime biting mosquito.

Courtesy CDC

Courtesy Goddard J. 2003.

Aedes aegypti• Worldwide within the

20°C isotherms.

• Vector of yellow fever and dengue.

• Urban mosquito.

• Daytime biting mosquito.

Recorded in Funchal, Recorded in Funchal, Madeira in 2004Madeira in 2004--2005.2005.Eurosurveillance, 20.11.2007Eurosurveillance, 20.11.2007

Courtesy Goddard J. 2003.

Courtesy CDC

Aedes albopictus

• Asian Tiger Mosquito.• Agressive, daytime

biting mosquito.• Associated with used

automobile tires.• Vector of yellow

fever, dengue and Lacrosse encephalitis virus.

Goddard J. 2003. CRC PressCourtesy Goddard J. 2003. CRC Press

Aedes albopictus

• Asian Tiger Mosquito.• Agressive, daytime

biting mosquito.• Associated with used

automobile tires.

Courtesy Goddard J. 2003. CRC Press

Aedes albopictus

• Asian Tiger Mosquito.• Agressive, daytime

biting mosquito.• Chikungunya outbreak

in Réunion, a French “overseas département”.

• Arboviral disease.• Fever and arthralgias.

Eurosurveillance. 2006. Volume 11. Issue 1, at http://www.eurosurveillance.org/

Courtesy Goddard J.

Aedes albopictus• Chikungunya fever in the

province of Ravenna, Italy: A. albopictus is the most likely vector …

• A. albopictus in … Belgium, the Netherlands, …

Eurosurveillance. 2007. Volume 12. Issue 9, at http://www.eurosurveillance.org/

• A. albopictus in NL: via “lucky bamboo” from SE-China.

Ned Tijdschr Geneeskd. 2007. 151:1333-1338.

Courtesy Goddard J.

Aedes albopictus

Chikungunya virus in Aedes albopictus, Italy.

2008. Emerging Infectious Diseases

14:852-854.

Courtesy Goddard J.

Anopheles labranchiae atroparvus

• Ziet gij muggen lang van poot? Aarzelt niet, maar slaat ze dood.

• Main malaria vector in the Low Countries.

• Lives in pig stables and attics.

• The larvae are found in brackish water along the coast from the southern Baltic to Spain.

Pictures by courtesy of Walter Reed.

CourtesyCourtesy

Anopheles freeborniAnopheles freeborni

Anopheles gambiae

• Most important vector in Africa.

• < 1000 m• 2 (7) km• 0 – 4 h maximal

activity.• Endophilic species.

Courtesy CDC

Anopheles gambiae

• 1930: Brazil.• 1937-1938: large fatal

epidemics associated with A. gambiae in Brazil.

• 1939-1941: eradicated from Brazil.

• 1943-1945: eradicated from Egypt.

The Lancet Infectious Diseases. 2002. 2:618-627.

UK NEQAS Parasitology on the web

Approximately 60 different species of Anopheles mosquitoes can transmit

malaria.

Malaria transmission

Mosquito to man

Blood transfusion

Mother to child

Alphonse Laveran(1845-1922)

• Physician of the French

Army.

• 1880: Constantine,

Algeria, The malaria

parasite: Laveriana,

Plasmodium.

• Nobel Prize in 1907.

Sir Ronald Ross (1857-1932)20 August 1897: mosquito day

• Surgeon-Major in the British Indian Medical Service wrote to his wife: “I know that this little thing a million men will save”.

• Studied bird malaria.• Nobel Prize in 1902.

Battista Grassi

• 1899• Only female

mosquitoes are able to transmit malaria.

• Blood is necessary for oogenesis.

Courtesy CDC

Courtesy

Plasmodium falciparumlimited to (sub-) tropical areas (summer isotherm of 20°C, altitude < 2000 m).

Sporogony in the mosquito

• Plasmodium falciparum– 8 days at 30°C– between 20 (18) and 33°C

• Plasmodium vivax– development occurs at 16°C

M. Wéry, 1995.

Developmental period in mosquito

• Plasmodium falciparum: 22 days at 20°C, 10 days at 27°C (minimal temperature (18) 2O°C)

• Plasmodium malariae: 30-35 days at 20°C, 25 days at 24°C (minimal temperature 16°C)

Beaver et al. 1984.

Developmental period in mosquito

• Plasmodium ovale: 16 days at 25°C, 14 days at 27°C (minimal temperature (18) 2O°C)

• Plasmodium vivax: 30+ days at 16°C, 16 days at 20°C, 10 days at 30°C (minimal temperature 16°C)

Beaver et al. 1984.

Malaria: Vector Control

• Source reduction (larval control)– Historically most effective campaign in Brazil

and Egypt (1930s and 1940s).– Bacillus thurigiensis var. israelensis (Bti

toxins).– Mosquito fish (Gambusia affinis): larger bodies

of water.

CDC, www.cdc.gov/malaria/

New strategy against Aedes aegyptiin Vietnam

Kay B., Nam V. 2005. Lancet: 365:613-617.• Major sources of A. aegypti are large water

storage containers.• 1998-2003: Elimination from 32 of 37

communes with Mesocyclops spp. (cyclopoid copepods) (309730 people).

• No dengue cases since 2002.

New strategy against Aedes aegyptiin Vietnam

Kay B., Nam V. 2005. Lancet: 365:613-617.• Mesocyclops spp. (cyclopoid copepods)• WHO: only in countries free of Guinea

worm (Mesocyclops spp. are intermediate host)

• Gnathostoma and Diphyllobothrium ?

Malaria: Vector Control

• Indoor residual spraying– DDT, dieldrin– more expensive insecticides– failure of eradication (1955-1969)– environmental concerns

• Insecticide-treated bed nets– pyrethroid insecticides– nets retreated at 6-12 months

CDC, www.cdc.gov/malaria/

DDT

• Dichloro-diphenyl-trichloroethane.

• 1874: German chemist: Othmer Zeidler.

• 1939: Paul Hermann Müller (1899-1965) in Switzerland (J.R. Geigy A.G., Basle).

• WWII: louse-borne typhus, malaria.

• 1948: Nobel Prize Medicine.

Courtesy Gentilini M. & Duflo B.

The disaster of the ban of DDT

The Lancet. 2000. 356: 265 and 1189.

2001: indoor residual spraying with DDT resumed in S. Africa and malaria cases fell. The Lancet. 2007. 369:1922.

Eradication of malaria

1934: Hans Andersag at Bayer discovers chloroquine1939: Paul Müller at Geigy discovers DDT1951: Sardinia malaria free1955: WHA (WHAssembly): goal of global eradication1955-1969: WHO uses DDT and chloroquine5050’’s: DDTs: DDT--resistanceresistance1962-1970: chloroquine-R1955-1965: expenditure of $ 1.4 billion1969: WHO back to malaria control1975: Europe free of malaria for

first time in history

Courtesy of C.D.C