Parasitology, Entomology and Bacteriology Question & Answers | MCQ Quiz | OmpathStudy Kenya

Question 1

Which one of the following genera is ODD one out in terms of pathogen transmission?

Accepted Answer

Bulinus — Bulinus is a genus of freshwater snails that serves as an intermediate host for schistosomes (trematodes), not an insect vector. Fannia, Musca, and Blatta are all insects (flies and cockroaches) that mechanically transmit pathogens. Bulinus transmits disease through a completely different mechanism involving parasitic life cycles rather than arthropod-mediated transmission. ---

Question 2

Which of the following diseases can be effectively controlled by the use of acaricides?

Accepted Answer

Q-fever — Q-fever is caused by Coxiella burnetii , which is transmitted by ticks (arachnids). Acaricides are chemicals that kill ticks and mites. Leishmaniasis is transmitted by sandflies, amoebiasis is spread through contaminated water/food, Katayama fever is caused by schistosomes (snail-transmitted), and sleeping sickness is transmitted by tsetse flies. Only Q-fever has a tick vector that can be controlled with acaricides. ---

Question 3

Which one of the following genera is a biological vector of scrub typhus pathogens?

Accepted Answer

Leptotrombidium — Leptotrombidium (formerly Trombicula ) mites are the biological vectors of Orientia tsutsugamushi , which causes scrub typhus. The mite larvae (chiggers) transmit the pathogen through their bite. Glossina transmits trypanosomes, Blatta is a cockroach (mechanical vector), Simulium transmits onchocerciasis, and Dermacentor transmits Rocky Mountain spotted fever and other tick-borne diseases. ---

Question 4

Which of the following pathogen can be transovarial transmitted by its biological vector?

Accepted Answer

Orientia tsutsugamushi — Orientia tsutsugamushi (scrub typhus agent) is transmitted transovarially in Leptotrombidium mites, meaning the pathogen passes from infected female mites to their offspring through eggs. This maintains the infection in mite populations without requiring infected hosts. Entamoeba is not vector-borne, while Onchocerca , Loa loa , and Wuchereria are filarial nematodes that require cyclical development in their vectors without transovarial transmission. ---

Question 5

Which of the following is the BEST treatment for scabies?

Accepted Answer

Benzyl benzoate — Benzyl benzoate is a topical scabicide used to treat Sarcoptes scabiei (scabies mite) infestations. It kills the mites and their eggs. Metronidazole treats protozoal infections, amphotericin B treats fungal infections, sodium stibogluconate treats leishmaniasis, and praziquantel treats helminthic infections. Permethrin cream is another common scabies treatment. ---

Question 6

Which of the following reagents can be used in the diagnosis of mites infection?

Accepted Answer

Liquid Iodine — Liquid iodine can be applied to skin to help visualize scabies burrows and mite tunnels, making them more visible for diagnosis. The iodine stains the burrows, helping identify the location of mites. Skin scrapings can then be examined microscopically. Crystal violet and safranin are bacterial stains, tetracycline is an antibiotic, and blood agar is a culture medium - none are specifically used for mite diagnosis. ---

Question 7

Indoor residual spraying is BEST effective against insects vectors of pathogens.

Accepted Answer

Endophilic — Indoor Residual Spraying (IRS) involves applying insecticides to interior walls and surfaces where vectors rest. It is most effective against endophilic insects that prefer to rest indoors after feeding. Exophagic insects feed outdoors, endophagic insects feed indoors but may rest outdoors, and exophilic insects rest outdoors - all reducing IRS effectiveness. Endophilic behavior maximizes contact with treated indoor surfaces. ---

Question 8

Which one of the following genera belongs to the family Argasidae?

Accepted Answer

Ornithodoros — Ornithodoros belongs to the family Argasidae (soft ticks), which lack a hard scutum and have mouthparts not visible from above. The other genera (Hyalomma, Amblyomma, Rhipicephalus, Boophilus) belong to Ixodidae (hard ticks), which have a hard dorsal shield and visible mouthparts. Argasid ticks typically feed rapidly and live in host burrows or nests. ---

Question 9

Which one of the following vectors utilizes one host in its life cycle and pathogen transmission?

Accepted Answer

Boophilus — Boophilus ticks are one-host ticks, completing their entire life cycle (larva, nymph, adult) on a single host animal. All feeding stages occur on the same host before the engorged female drops off to lay eggs. Haemaphysalis and Amblyomma are typically three-host ticks, Hyalomma can be two or three-host, and Ornithodoros (soft tick) is a multi-host feeder. ---

Question 10

Which one of the following vectors of pathogen is BEST controlled by using boric acid powder e.g. borax?

Accepted Answer

Periplanetta species — Periplanetta (American cockroach) and other cockroaches are effectively controlled using boric acid powder (borax), which acts as a stomach poison when ingested during grooming. It damages the insect's digestive system and exoskeleton. Pediculus (body louse), Pthirus (crab louse), Ixodes (tick), and Tunga (jigger flea) require different control methods such as topical insecticides or acaricides. ---

Question 11

Which of the following vectors is commonly found in central and southern America?

Accepted Answer

Lutzomyia species — Lutzomyia sandflies are the New World (Americas) vectors of leishmaniasis, commonly found in Central and South America. Phlebotomus sandflies transmit leishmaniasis in the Old World (Africa, Asia, Europe). Chrysops (deer flies) and Simulium (black flies) have wider distributions. The geographic distribution of sandfly genera is an important epidemiological distinction. ---

Question 12

The disease pathogen transmitted by Triatoma species is BEST treated using?

Accepted Answer

Nifurtimox — Triatoma (kissing bugs/reduviid bugs) transmit Trypanosoma cruzi , which causes Chagas disease (American trypanosomiasis). Nifurtimox and benznidazole are the primary treatments for acute Chagas disease. Melarsoprol, pentamidine, and eflornithine treat African trypanosomiasis (sleeping sickness), while metriphonate treats schistosomiasis. ---

Question 13

Which one of the following has NOT resulted into increase of Cimex geographical dispersion?

Accepted Answer

None of the above — All the listed factors (A-D) have contributed to the increased geographical dispersion and resurgence of Cimex (bedbugs). Global travel spreads bedbugs between locations, insecticide resistance allows populations to survive control efforts, warmer houses provide optimal breeding conditions, and increased human population density provides more hosts and harborage sites. Therefore, none of the listed options has NOT contributed (all have contributed). ---

Question 14

Petroleum jelly will be important in the management of?

Accepted Answer

Pthirus pubis — Petroleum jelly (Vaseline) can be used to treat Pthirus pubis (pubic lice/crab lice) infestations by smothering the lice and creating an occlusive barrier. While it can also provide some benefit for other lice species, it is particularly recommended for pubic lice due to the sensitive nature of the affected area. However, "E) All of the above" could be argued as petroleum jelly can help manage all these ectoparasites through mechanical suffocation. ---

Question 15

Which one of the following vectors predisposes humans to plague?

Accepted Answer

Pulex species — Pulex irritans (human flea) and Xenopsylla cheopis (rat flea) are the primary flea vectors of Yersinia pestis , which causes plague. Fleas transmit the bacteria from infected rodents to humans through their bite. Musca and Fannia are flies (mechanical vectors of various pathogens), Glossina transmits trypanosomiasis, and Simulium transmits onchocerciasis. ---

Question 16

Which of the following are vectors of typhoid pathogens?

Accepted Answer

True flies — True flies (Order Diptera), particularly Musca domestica (housefly), are mechanical vectors of Salmonella typhi and S. paratyphi (typhoid pathogens). Flies contaminate food and water after contact with feces containing the bacteria. Haemagogus and Sabethes are mosquito genera that transmit yellow fever, Fannia flies can mechanically transmit various pathogens, and Stomoxys (stable fly) is a biting fly. ---

Question 17

Arboviruses are mainly transmitted by…

Accepted Answer

All of the above — Arboviruses (arthropod-borne viruses) are transmitted by multiple arthropod vectors. Aedes mosquitoes transmit dengue, yellow fever, Zika, and chikungunya. Culex mosquitoes transmit West Nile virus and Japanese encephalitis. Culicoides (biting midges) transmit various arboviruses affecting livestock and occasionally humans. While Cimex (bedbugs) are not typically major arbovirus vectors, some arboviruses can be transmitted by multiple arthropod groups. ---

Question 18

Anthropophilic vectors prefer?

Accepted Answer

Human hosts — Anthropophilic vectors show a feeding preference for human hosts. "Anthropo-" refers to humans, and "-philic" means loving or preferring. This host preference is epidemiologically important as it increases disease transmission to humans. Examples include Anopheles gambiae (highly anthropophilic malaria vector) and Aedes aegypti (dengue vector). Zoophilic vectors prefer animals, and ornithophilic vectors prefer birds. ---

Question 19

Exophagic insects prefer?

Accepted Answer

Feeding outdoors — Exophagic insects prefer to feed outdoors on hosts. "Exo-" means outside, and "-phagic" refers to feeding behavior. This is distinguished from endophagic (feeding indoors), exophilic (resting outdoors), and endophilic (resting indoors). Exophagic behavior reduces the effectiveness of indoor interventions like IRS (Indoor Residual Spraying) and bed nets. ---

Question 20

Presence of chrysops in the environment predisposes the community to…infections?

Accepted Answer

Conjunctivitis — Chrysops (deer flies) can transmit Loa loa (eye worm), which causes loiasis. The adult worms can migrate across the conjunctiva of the eye, causing conjunctivitis and "calabar swellings." While Chrysops is also associated with the transmission of the parasite that can cause eye irritation, conjunctivitis is the direct result of the worm's presence. River blindness is transmitted by Simulium , and trachoma is caused by Chlamydia trachomatis . ---

Question 21

Which stage of filarial nematodes will you find in the chest muscles of their vectors?

Accepted Answer

Larval stage 3 — In the filarial nematode life cycle, microfilariae are ingested by the arthropod vector during a blood meal. Inside the vector, they develop through L1 and L2 stages in the midgut, then migrate to the thoracic (chest) muscles where they develop into the infective L3 (third larval stage). The L3 larvae then migrate to the mouthparts and are transmitted to a new host during the next blood meal. ---

Question 22

Pediculosis can be best treated with?

Accepted Answer

Insecticides — Pediculosis (lice infestation) is best treated with topical insecticides such as permethrin, malathion, or pyrethrin-based products. These pediculicides kill both adult lice and nits (eggs). While fine-toothed combs (nit combs) are important adjunct tools for physically removing lice and eggs, insecticides provide the most effective treatment. Antibiotics don't kill lice, bed nets don't prevent lice, and Vaseline is less effective than proper pediculicides. ---

Question 23

Which of the following arthropods is most likely to be monophagous?

Accepted Answer

Louse — Monophagous organisms feed on only one type of food source or host. Lice are highly host-specific, with each species typically feeding on only one host species (e.g., Pediculus humanus on humans only). Fleas, mosquitoes (Culex, Anopheles), and ticks are generally more polyphagous, feeding on multiple host species, though they may show preferences. ---

Question 24

Aedes albopictus is mainly found in?

Accepted Answer

Asia — Aedes albopictus (Asian tiger mosquito) is native to Southeast Asia and was originally mainly found in Asia. However, it has become invasive worldwide, spreading to Africa, Europe, the Americas, and other regions through global trade (especially used tire shipments). While now found globally, Asia remains its primary native region and area of highest prevalence. ---

Question 25

Mosquito life cycle has larval instars.

Accepted Answer

Four — Mosquitoes undergo complete metamorphosis with four larval instars (developmental stages between molts): L1, L2, L3, and L4. After the fourth instar, the larva molts into a pupa, which then emerges as an adult mosquito. Each larval instar is progressively larger, with the fourth instar being the largest before pupation. ---

Question 26

Which one of the following is a repellant?

Accepted Answer

DEET — DEET (N,N-diethyl-meta-toluamide) is the most effective and widely used insect repellent, applied to skin to prevent insect bites. DDT is an organochlorine insecticide (now banned in many countries), permethrin is a pyrethroid insecticide, and bendiocarb is a carbamate insecticide. These are insecticides that kill insects rather than repel them, though permethrin can also have some repellent properties when applied to clothing. ---

Question 27

Which one has the GABA site as its target?

Accepted Answer

Bendiocarb — Bendiocarb is a carbamate insecticide that targets the GABA (gamma-aminobutyric acid) receptor-chloride channel complex in insects, causing hyperexcitation. DDT and permethrin target voltage-gated sodium channels, DEET is a repellent (not an insecticide), and malathion is an organophosphate that inhibits acetylcholinesterase. Carbamates and organochlorines like lindane target GABA receptors. ---

Question 28

Presence of anthills could predispose the population to?

Accepted Answer

Leishmaniasis — Anthills and rodent burrows provide breeding sites for sandflies ( Phlebotomus and Lutzomyia species), which are vectors of leishmaniasis. Sandflies rest and breed in dark, humid environments like animal burrows, termite mounds, and anthills. The presence of these structures near human habitation increases sandfly populations and leishmaniasis transmission risk. ---

Question 29

People living in forested areas like Arabuko Sokoke are at a risk of?

Accepted Answer

Sleeping sickness — Arabuko Sokoke is a forest in Kenya where tsetse flies ( Glossina species) thrive in wooded and forested areas. These flies transmit Trypanosoma parasites causing African trypanosomiasis (sleeping sickness). Forest-dwelling Glossina species from the fusca group are particularly associated with forested habitats. While malaria can also occur in such areas, the specific mention of forested habitat strongly suggests sleeping sickness. ---

Question 30

Which of the following vectors transmit Trypanosome parasites in Latin America?

Accepted Answer

Triatomine bugs — Triatomine bugs (kissing bugs, family Reduviidae) transmit Trypanosoma cruzi , causing Chagas disease (American trypanosomiasis) in Latin America. They defecate while feeding, and the parasite enters through the bite wound or mucous membranes. Glossina (tsetse flies) transmit African trypanosomiasis in Africa. Cimex (bedbugs), Chrysops (deer flies), and Simulium (black flies) transmit different pathogens. ---

Question 31

Pruritis can be best diagnosed for?

Accepted Answer

Sarcoptes scabiei — Pruritus (intense itching) is the hallmark symptom of scabies, caused by Sarcoptes scabiei mites burrowing in the skin. The itching is caused by an allergic reaction to the mites, their eggs, and feces. While lice (Pediculus, Pthirus) and Leptotrombidium (chiggers) also cause itching, scabies produces the most intense and persistent pruritus, particularly at night. Blattella (cockroaches) don't typically cause pruritus. ---

Question 32

If you found lice eggs (nits) in someone's clothing, what species would they most likely be from?

Accepted Answer

Pediculus humanus — Pediculus humanus corporis (body louse) is the only louse species that lives and lays eggs (nits) in clothing seams and fabric rather than directly on the body. Pediculus capitis (head louse) attaches nits to hair shafts on the head, and Pthirus pubis (crab louse/pubic louse) attaches eggs to pubic and body hair. Finding nits in clothing is diagnostic of body lice. ---

Question 33

Snails are both first and second intermediate hosts of?

Accepted Answer

Echinostoma ilocanum — Echinostoma ilocanum uses snails as both first and second intermediate hosts - the miracidium penetrates a snail (first intermediate host), develops through sporocyst and redia stages, then cercariae emerge and encyst in the same or different snail species (second intermediate host). Fasciola and Fasciolopsis use snails as first intermediate hosts only, Hymenolepis nana can complete its cycle without intermediate hosts, and Paragonimus uses snails then crustaceans. ---

Question 34

How can some millipedes cause medical problems?

Accepted Answer

Spraying defensive secretions — Some millipedes defend themselves by secreting or spraying toxic chemicals (benzoquinones, hydrogen cyanide) from their defensive glands. These secretions can cause skin irritation, burns, blistering, and eye damage in humans. Millipedes don't sting (no stinger), don't transmit diseases as vectors, and don't lay eggs in human tissue. This is a chemical defense mechanism rather than a bite or sting. ---

Question 35

Holometabolous insects have?

Accepted Answer

4 life stages — Holometabolous insects undergo complete metamorphosis with four distinct life stages: egg, larva, pupa, and adult. Examples include mosquitoes, flies, fleas, and beetles. This is contrasted with hemimetabolous (incomplete metamorphosis) insects that have three stages: egg, nymph, and adult, without a pupal stage. The pupal stage is the defining characteristic of holometabolous development. ---

Question 36

Rift valley fever is mainly transmitted by?

Accepted Answer

Aedes species — Rift Valley fever virus is primarily transmitted by Aedes mosquitoes, particularly Aedes mcintoshi and other floodwater Aedes species. The virus is associated with heavy rainfall and flooding that creates breeding sites for these mosquitoes. While Culex and other mosquitoes can transmit RVF to some degree, Aedes species are the principal vectors. Toxorhynchitinae don't feed on blood and aren't disease vectors. ---

Question 37

Autogenous insects are?

Accepted Answer

None of the above — Autogenous insects (specifically mosquitoes) can develop their first batch of eggs without taking a blood meal, using nutritional reserves from the larval stage. This is different from anautogenous species that require blood for egg development. The question options don't correctly define autogeny - it's about egg development without blood feeding, not about mating. Option A describes parthenogenesis, not autogeny. ---

Question 38

Parthenogenesis is a type of?

Accepted Answer

Asexual reproduction in which offspring develops from unfertilized eggs — Parthenogenesis is a form of asexual reproduction where embryos develop from unfertilized eggs without fertilization by sperm. This occurs in some aphids, bees (producing drones), and other arthropods. Since no genetic contribution from a male is required, it's classified as asexual reproduction. Options B and C involve fertilized eggs (sexual reproduction), and option D is contradictory. ---

Question 39

The best mode of malaria control is?

Accepted Answer

Integrated vector management — Integrated Vector Management (IVM) is the best approach as it combines multiple control strategies: larval control, insecticide-treated bed nets, indoor residual spraying, environmental management, biological control, and case management. While bed nets, prompt treatment, and larval control are all important, IVM's comprehensive multi-intervention approach is most effective for sustainable malaria control. Single interventions are less effective than integrated strategies. ---

Question 40

Which insects are included in the order Blattaria?

Accepted Answer

Cockroaches — Order Blattaria (or Blattodea) includes cockroaches only. Lice belong to Order Phthiraptera, true flies belong to Order Diptera, and beetles belong to Order Coleoptera. Each insect order represents a distinct taxonomic group with characteristic features. Cockroaches are characterized by flattened bodies, long antennae, and incomplete metamorphosis. ---

Question 41

Which of the following insects is included in the order diptera?

Accepted Answer

True flies — Order Diptera includes all true flies (mosquitoes, house flies, midges, black flies, sandflies, etc.). "Diptera" means "two wings," referring to their single pair of functional wings with the hind wings modified into halteres for balance. Cockroaches are Order Blattodea, lice are Order Phthiraptera, and fleas are Order Siphonaptera. ---

Question 42

Which of the following insects transmits cholera pathogens?

Accepted Answer

True flies — True flies, particularly Musca domestica (housefly) and cockroaches, mechanically transmit Vibrio cholerae (cholera pathogen) by contaminating food and water after contact with infected feces. The table in the document shows both Blatta orientalis and Musca domestica as vectors. Haemagogus and Sabethes transmit yellow fever, Fannia can transmit various pathogens but is not a primary cholera vector, and Stomoxys is a biting fly. ---

Question 43

What kinds of roaches might you expect to encounter in Athens?

Accepted Answer

All of the above — In Athens (presumably Athens, Georgia, USA, given the context), all three cockroach species commonly occur. German cockroaches ( Blattella germanica ) are common indoor pests, American cockroaches ( Periplaneta americana ) inhabit sewers and basements, and smoky brown cockroaches ( Periplaneta fuliginosa ) are common in the southeastern United States. Urban and suburban environments typically harbor multiple cockroach species. ---

Question 44

What is the main advantage of using larval control against mosquitoes?

Accepted Answer

Larvae are restricted to confined aquatic habitats that can be treated — The main advantage of larval control is that mosquito larvae are confined to specific, identifiable aquatic breeding sites that can be targeted with larvicides or environmental management. This is more efficient than trying to control widely dispersed flying adults. Larval habitats can be drained, treated with biological agents (Bti, fish), or chemically treated. However, option C is incorrect as larval habitats do support other organisms. ---

Question 45

What are effective non-pesticide ways to control problems from cockroaches?

Accepted Answer

All of the above — Integrated pest management (IPM) for cockroaches includes multiple non-chemical approaches. Storing food in sealed containers eliminates food sources, regular cleaning removes crumbs and food debris that attract roaches, and sealing entry points (cracks, gaps around pipes) prevents cockroach entry and eliminates harborage sites. All three methods work synergistically to create an environment unfavorable for cockroach infestation without using pesticides. ---

Question 46

The pupal stage is found in:

Accepted Answer

Complete metamorphosis — The pupal stage is the defining characteristic of complete (holometabolous) metamorphosis, which includes four life stages: egg, larva, pupa, and adult. During the pupal stage, dramatic reorganization occurs as larval tissues break down and adult structures form. Incomplete (hemimetabolous) metamorphosis has only three stages: egg, nymph, and adult, with no pupal stage. Insects like mosquitoes, flies, and beetles undergo complete metamorphosis. ---

Question 47

What is simulotoxicosis?

Accepted Answer

A negative reaction to the saliva of black flies — Simulotoxicosis is a toxic reaction caused by the saliva of black flies ( Simulium species) injected during blood feeding. In livestock and occasionally humans, massive black fly attacks can cause severe reactions including swelling, hemorrhage, fever, and even death due to the toxic and allergenic components in the saliva. This is distinct from the parasitic diseases (onchocerciasis) that black flies transmit. It's not related to pesticides or viruses. ---

Question 48

How does insecticide resistance develop?

Accepted Answer

B and C — Insecticide resistance develops through selection pressure when insecticides are used. Low doses allow insects with partial resistance genes to surviv

Parasitology, Entomology and Bacteriology Question &amp; Answers | MCQ Quiz | OmpathStudy Kenya

Questions, Answers & Explanations

Parasitology, Entomology and Bacteriology Question & Answers | MCQ Quiz | OmpathStudy Kenya