Medical Microbiology

616 11 Arthropods

Bugs(Heteroptera)

Cimexlectularius(familyCimicidae),thebedbug,occursworldwide.Nowrareincen-

tralEurope,itisthereforeoftennotconsideredwhendiagnosingskinlesions.Bed-

bugsliveonhumanblood.Especiallyinrepeatedinfestations,theirbitesinduce

hemorrhagicorurticarial-papulousreactions,oftenvisibleaslesionsarrangedin

groupsorrows.Thebugsareabout 3 – 4 mmlong,withdorsoventrallyflattened

bodies,greatlyreducedwingsandabloodsuckingproboscisthatcanbefolded

backventrally.Developmentfromtheeggthroughfivelarvalstagestotheadults

takesaboutoneandahalfmonthsundersuitableconditions,butcanbeextended

toaslongasoneyear.Bedbugsrequireseveralbloodmealsduringdevelopment

andeggproduction.Theirabilitytostarveforaslongasayearmeanstheycan

persistforlongperiodsinrooms,hidingbyday(undermattresses,behindfurniture,

incracksinthewalls,etc.)andemergingatnightquestingforabloodmeal.Diag-

nosis:skinlesionsanddetectionofbugsinthevicinity.Therapy:symptomatic.Con-

trolbymeansofroomdecontamination.Otherbugsdoattimesbitehumans,e.g.,

theswallowbug(Oeciacushirundinis),whichsometimesleavebirds’neststoinvade

humandwellings.BugsofthefamilyReduviidae(generaTriatoma,Rhodnius,etc.)

transmitChagasdisease(seep. 49 1).

MosquitoesandFlies

(Diptera:NematoceraandBrachycera)

&Manydipteranspeciesactasvectorsofpathogens.Theirbitesalsocause

localreactions,andflymaggotsmayevenpenetrateintoandcolonizethe

skin,wounds,ornaturalorifices,therebycausingconsiderabletissuedam-

age. &

Roleasvectors.ManyspeciesofNematoceraaresignificantvectorsofpatho-

gens,e.g.,Anophelesmosquitoestransmittingthemalariaparasites,Aedes

aegyptiwhichistheprincipalvectoroftheDenguevirus,orPhlebotomus

sandflies(Fig. 11 .1e)transmittingthecausative agentsofleishmanioses

(seeChapter9).Nematocera alsotransmitmanyotherpathogens—not

onlyinthetropics,butincentralEuropeaswell.

Thesameappliestonumerousflyspeciese.g.,Glossinaflies,thevectorsof

thesleepingsicknessagents.Fliescanalsodisseminatevariouspathogens

mechanically(e.g.,bacteria,parasites).

Bitereactions.ThebitesofNematoceraandfliescancausemoreorlesspro-

nouncedprimarydermalreactions(e.g.,mosquitoesofthegenusAedesor

blackfliesofthefamilySimuliidae)orallergicskinreactions.

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Kayser, Medical Microbiology © 2005 Thieme