Question 1

Disease that transmited from one person to another person are called?

Accepted Answer

Answer reason: Diseases that spread from one person to another are communicable and are caused by infectious agents, hence termed infectious diseases. Venereal diseases are a subset of infectious diseases limited to sexual transmission, so they are not the general term. Hereditary diseases are genetic and not transmitted via person-to-person contact. Therefore, the best single answer is infectious disease.

Question 2

Which of the following diseases usually spreads through air?

Accepted Answer

Answer reason: Tuberculosis is transmitted via airborne droplet nuclei that can remain suspended and be inhaled, requiring airborne precautions. Typhoid and cholera are primarily spread by the fecal–oral route through contaminated food and water. Plague typically spreads via flea vectors or contact with infected animals; only pneumonic plague can be airborne but is not the usual route. Therefore, tuberculosis is the correct choice.

Question 3

Which one is not a Viral Disease?

Accepted Answer

Answer reason: Typhoid is caused by the bacterium Salmonella enterica serotype Typhi, transmitted via the fecal–oral route. In contrast, dengue is caused by dengue virus (a flavivirus), AIDS is caused by HIV (a retrovirus), and influenza is caused by influenza viruses (orthomyxoviruses). Therefore, typhoid is not a viral disease.

Question 4

Disease is caused by dog bite ...?

Accepted Answer

Answer reason: Rabies is caused by a neurotropic RNA virus transmitted through the saliva of infected animals, most commonly via dog bites. After inoculation, the virus travels along peripheral nerves to the central nervous system, leading to encephalitis and classic symptoms such as hydrophobia and aerophobia. Scurvy is due to vitamin C deficiency, colorblindness is a genetic condition, and 'madness' is not a specific infectious disease.

Question 5

A specimen for anaerobic culture is place in an anaerobic holding jar in order to?

Accepted Answer

Answer reason: Anaerobic organisms are inhibited or killed by oxygen, so specimens must be kept in an oxygen-free environment to preserve viability. An anaerobic holding jar maintains reduced conditions using gas-generating systems and catalysts until culture processing. It is not used to promote spore formation, speed growth, or protect from UV light.

Question 6

Which disease has been completely eradicated globally?

Accepted Answer

Answer reason: Smallpox, caused by the variola virus, is the only human disease certified by the WHO as eradicated (1980) after a successful global vaccination campaign. Chickenpox (varicella), mumps, and diphtheria still occur worldwide, though vaccines have greatly reduced their incidence. No natural cases of smallpox have occurred since eradication, with remaining virus stocks limited to secure laboratories.

Question 7

The mumps virus is transmitted through?

Accepted Answer

Answer reason: Mumps, caused by a paramyxovirus, spreads person-to-person via respiratory droplets and direct contact with saliva from an infected individual. It is not vector-borne, so mosquito transmission does not occur. Blood transfusion and fecal–oral routes are not recognized modes of transmission. Therefore droplet spread is the correct route.

Question 8

Malaria parasites multiply inside which cells?

Accepted Answer

Answer reason: Plasmodium species undergo asexual replication in erythrocytes during the blood stage of malaria. Merozoites invade red blood cells and multiply as trophozoites and schizonts, leading to RBC rupture and cyclical fevers. White blood cells, platelets, and plasma cells are not sites of Plasmodium replication.

Question 9

HBsAg positivity more than 6 months indicates?

Accepted Answer

Answer reason: HBsAg indicates the presence of hepatitis B surface antigen, reflecting active HBV infection. Persistence of HBsAg for more than 6 months defines chronic hepatitis B and the chronic carrier state. Immunity (from recovery or vaccination) is indicated by anti-HBs, not persistent HBsAg. Acute infection is typically under 6 months and associated with IgM anti-HBc.

Question 10

Following is the marker of HIV infection in blood?

Accepted Answer

Answer reason: HIV is a retrovirus whose hallmark enzyme is reverse transcriptase, which synthesizes DNA from viral RNA. Detection of reverse transcriptase activity in blood has historically been used as a marker of retroviral infection. DNA and RNA polymerases are cellular enzymes and are not specific to HIV. Therefore, reverse transcriptase best indicates HIV infection.

Question 11

Asexual reproduction in Penicillium fungus usually takes place through?

Accepted Answer

Answer reason: Penicillium reproduces asexually by forming conidia on specialized aerial hyphae called conidiophores, which disperse and germinate into new mycelia. Budding and fission are typical of yeasts (e.g., Saccharomyces for budding, Schizosaccharomyces for fission), not filamentous molds like Penicillium. Gemmules are resistant reproductive structures of some sponges, not fungi. Therefore, conidia is the correct mechanism.

Question 12

Yellow fever is an infectious disease usually transmitted by?

Accepted Answer

Answer reason: Yellow fever is caused by a flavivirus transmitted to humans primarily by Aedes aegypti mosquitoes, and in jungle cycles by Haemagogus and Sabethes mosquitoes. These vectors acquire the virus from infected primates and pass it to humans via bites. Honeybees and rats are not vectors for yellow fever, and 'files/flies' are not implicated in its transmission.

Question 13

Which hepatitis spread through oral fecal route-?

Accepted Answer

Answer reason: Hepatitis A virus is classically transmitted via the fecal–oral route, often through contaminated food or water or close contact. In contrast, hepatitis B and C are primarily bloodborne and sexually/perinatally transmitted. Although hepatitis E can also spread fecal–orally, the prototypical and most commonly tested fecal–oral hepatitis is HAV, making it the single best answer here.

Question 14

People should be taught to avoid food products in bulged cans because they might contain?

Accepted Answer

Answer reason: Bulging cans indicate gas production under anaerobic conditions, classically due to Clostridium botulinum growth and toxin formation in improperly canned foods. C. botulinum spores survive inadequate heating and germinate in low-oxygen environments of sealed cans. C. tetani is associated with wound contamination, not canned food. E. coli and Salmonella can contaminate foods but are not the typical cause of gas-swollen cans or botulism risk.

Question 15

A typical rash that appear on the skin of a typhoid patient is called ...?

Accepted Answer

Answer reason: Typhoid fever (Salmonella typhi) classically presents with rose spots—faint, salmon-colored macules on the trunk, appearing around the second week of illness. Koplik’s spots are enanthem seen on the buccal mucosa in measles, not typhoid. Ryle’s refers to a type of nasogastric tube, and “Leyman’s spot” is not associated with typhoid. Therefore, the characteristic rash is the rose spot.

Question 16

Which infectious disease can result in severe birth defects if contracted by a pregnant woman during the first trimester?

Accepted Answer

Answer reason: Rubella infection in early pregnancy can cross the placenta and cause congenital rubella syndrome, with a very high risk of severe anomalies if exposure occurs in the first trimester. Classic defects include sensorineural deafness, cataracts, and congenital heart disease (e.g., PDA). Measles (rubeola) and roseola are not typically associated with congenital malformations. Varicella can cause congenital varicella syndrome, but rubella is the prototypical and most strongly teratogenic viral infection in the first trimester.

Question 17

Dog bite causes which Disease?

Accepted Answer

Answer reason: Dog bites can transmit the rabies virus through infected saliva, leading to an almost uniformly fatal encephalitis if untreated. Ringworm is a fungal skin infection acquired by contact, not typically by a bite. Cancer and heart attack are unrelated to dog bites. Immediate wound cleansing and post-exposure prophylaxis are indicated for suspected rabies exposures.

Question 18

What type of virus is HIV?

Accepted Answer

Answer reason: HIV is a retrovirus (genus Lentivirus) with a single-stranded, positive-sense RNA genome. It carries reverse transcriptase, which converts its RNA into DNA after entering the host cell. The viral DNA then integrates into the host genome as a provirus. Thus, it is classified as an RNA virus.

Question 19

Yeast is a ...?

Accepted Answer

Answer reason: Yeasts are unicellular eukaryotic organisms classified within the kingdom Fungi. They reproduce asexually by budding or fission and include species such as Saccharomyces and Candida. They are not bacteria (prokaryotes), viruses (acellular), or algae (photosynthetic protists).

Question 20

An agent which kills pathogenic bacteria called?

Accepted Answer

Answer reason: A disinfectant is a chemical agent that destroys pathogenic microorganisms on inanimate objects and surfaces. Asepsis refers to the state of being free from disease-causing organisms, not an agent. A fomite is an object that can transmit infection. A bacteriostat inhibits bacterial growth but does not kill bacteria.

Question 21

Recent influenza Pandemic was due to?

Accepted Answer

Answer reason: The 2009 global influenza pandemic was caused by the novel Influenza A(H1N1)pdm09 virus, a reassortant of swine, avian, and human strains that spread efficiently person-to-person worldwide. H5N1 and H7N7 are avian influenza viruses that have caused sporadic zoonotic outbreaks but no sustained human transmission leading to a pandemic. H3N2 commonly contributes to seasonal influenza but was not responsible for the most recent pandemic. Therefore, H1N1 is the correct choice.

Question 22

Which of the following causative organism responsible for Syphilis?

Accepted Answer

Answer reason: Syphilis is caused by Treponema pallidum, a motile spirochete transmitted primarily through sexual contact and capable of causing primary, secondary, latent, and tertiary disease. HIV is a retrovirus that causes AIDS, not syphilis. Sarcoptes scabiei is a mite responsible for scabies. Neisseria gonorrhea causes gonorrhea, a different sexually transmitted infection.

Question 23

Mumps affects mainly which gland?

Accepted Answer

Answer reason: Mumps virus (a paramyxovirus) has a predilection for the salivary glands, especially the parotid glands, leading to painful parotitis and swelling near the jaw. While mumps can involve other organs such as the testes and pancreas, the classic and primary site of involvement is the parotid gland. Therefore, the best answer is the parotid.

Question 24

Common cold is mainly caused by?

Accepted Answer

Answer reason: The common cold is most often caused by viruses, particularly rhinoviruses, with contributions from coronaviruses and others. These pathogens infect the upper respiratory tract and are self-limiting in immunocompetent hosts. Bacteria, fungi, and protozoa are not typical etiologies of uncomplicated common cold, which is why antibiotics are ineffective for routine cases.

Question 25

Chickenpox mainly spreads through?

Accepted Answer

Answer reason: Varicella-zoster virus (chickenpox) is primarily transmitted via airborne droplet nuclei and aerosols from respiratory secretions, especially 1–2 days before rash onset until lesions crust. Direct contact with vesicle fluid can also spread it, but the main mode is airborne. It is not vector-borne, waterborne, or transmitted via blood transfusion.

Question 26

Mad cow disease affects?

Accepted Answer

Answer reason: Mad cow disease is bovine spongiform encephalopathy (BSE), a prion disease that primarily affects cattle. The prion can be transmitted to humans through consumption of contaminated beef products, causing variant Creutzfeldt–Jakob disease (vCJD). Thus it affects both cattle and humans, not birds, and not humans alone.

Question 27

Yellow fever is spread through?

Accepted Answer

Answer reason: Yellow fever virus is transmitted to humans by the bite of infected mosquitoes, primarily Aedes aegypti and Haemagogus species. It is not spread by ticks or fleas, and it is not waterborne. Prevention centers on mosquito control, bite avoidance, and vaccination.

Question 28

Zika virus is spread by?

Accepted Answer

Answer reason: Zika virus is primarily transmitted to humans through the bite of infected Aedes mosquitoes (A. aegypti and A. albopictus). It is not spread via water, food, or through airborne routes. Additional routes like sexual and vertical (mother-to-fetus) transmission exist, but the classic mode is mosquito bite.

Question 29

Schistosomiasis is a?

Accepted Answer

Answer reason: Schistosomiasis requires freshwater habitats with specific snail intermediate hosts; human infection occurs when cercariae penetrate the skin during water contact. This makes it a water-based disease dependent on an aquatic ecosystem, not ingestion. It is not water-borne (not transmitted by drinking water) and not water-washed (not primarily due to inadequate water for hygiene).

Question 30

A Widal test is done to diagnose the possibility of having ________?

Accepted Answer

Answer reason: The Widal test detects agglutinating antibodies (O and H antigens) against Salmonella Typhi and Paratyphi, which cause enteric (typhoid/paratyphoid) fever. It is not used to diagnose malaria, measles, or ear infections. Interpretation relies on a significant titer or a fourfold rise in paired sera due to limited specificity and cross-reactivity.

Question 31

The most common cause of UTI is ____?

Accepted Answer

Answer reason: Escherichia coli from the gastrointestinal tract is the predominant uropathogen causing community-acquired urinary tract infections via ascending infection through the urethra. Its fimbriae facilitate adhesion to uroepithelial cells, promoting colonization. Staphylococcus saprophyticus is a less common cause, mainly in young women, and Streptococcus and Salmonella are uncommon causes of UTI.

Question 32

Which test is commonly used for initial HIV screening?

Accepted Answer

Answer reason: Initial HIV screening is performed with a serologic antigen/antibody immunoassay, commonly an ELISA-based test (4th-generation Ag/Ab). Western blot was historically used as a confirmatory assay, not for screening. PCR (NAT) is used for early detection, confirmation of indeterminate results, or in infants. A CBC does not diagnose HIV infection.

Question 33

Koplik’s spots are seen in which disease?

Accepted Answer

Answer reason: Koplik spots are small bluish-white lesions on the buccal mucosa opposite the molars that appear 1–2 days before the measles exanthem and are considered pathognomonic for measles (rubeola). Tuberculosis and diphtheria do not produce these oral enanthem findings. Pertussis causes paroxysmal cough with inspiratory whoop, not Koplik spots.

Question 34

The measles virus is sensitive to?

Accepted Answer

Answer reason: Measles (rubeola) is an enveloped paramyxovirus that is environmentally labile. Ultraviolet radiation in sunlight rapidly inactivates the virus by damaging its nucleic acid and disrupting the fragile lipid envelope. This light sensitivity contributes to the virus’s short survival outside the host and the need for close-contact transmission.

Question 35

The infective form of malarial parasite for humans is?

Accepted Answer

Answer reason: In malaria transmission, the female Anopheles mosquito injects sporozoites into humans during a blood meal. Sporozoites invade hepatocytes to begin the liver stage of infection. Merozoites are produced in the liver and infect red blood cells, while gametocytes are the stage infective to mosquitoes. Trophozoites are an intraerythrocytic growth stage, not the infective form for humans.

Question 36

Measles belongs to which virus family?

Accepted Answer

Answer reason: Measles virus is an enveloped, negative-sense single-stranded RNA virus in the family Paramyxoviridae, genus Morbillivirus. Retroviruses include HIV, not measles. Herpesviruses are double-stranded DNA viruses like HSV and VZV, and poxviruses include variola. Therefore, the correct family is Paramyxovirus.

Question 37

Measles is also known as?

Accepted Answer

Answer reason: Measles is the common name for rubeola, caused by the measles virus (a Morbillivirus in the Paramyxoviridae family). Rubella is a different disease known as German measles caused by a togavirus. Chickenpox is caused by varicella-zoster virus, and smallpox by variola virus. Therefore, the correct synonym for measles is rubeola.

Question 38

The incubation period of measles is usually?

Accepted Answer

Answer reason: Measles (rubeola) has an incubation period that typically averages 10–12 days from exposure to onset of prodromal symptoms, with rash appearing around day 14. The commonly cited range is about 7–14 days, though it can rarely extend up to ~21 days. Therefore, among the options provided, 7–14 days is the correct usual incubation period.

Question 39

COVID-19 is caused by?

Accepted Answer

Answer reason: COVID-19 is the illness caused by the novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Influenza viruses cause seasonal flu, not COVID-19. HIV causes AIDS, and hepatitis viruses cause various forms of hepatitis. Therefore, the correct etiologic agent is SARS-CoV-2.

Question 40

Malaria is a type of?

Accepted Answer

Answer reason: Malaria is caused by Plasmodium parasites transmitted to humans through the bite of infected female Anopheles mosquitoes, which are biological vectors. It is not caused by fungi and is not spread via water or respiratory droplets. Therefore, it is classified as a vector-borne disease.

Question 41

Amoebic dysentery is caused by?

Accepted Answer

Answer reason: Amoebic dysentery is caused by the protozoan parasite Entamoeba histolytica, transmitted via the fecal–oral route. Trophozoites invade the colonic mucosa, producing flask-shaped ulcers and bloody, mucus-containing diarrhea. Shigella and certain E. coli cause bacillary dysentery, while Salmonella more commonly causes gastroenteritis or typhoid fever, not amoebic dysentery.

Question 42

Carrier state in Typhoid occurs due to bacteria persisting in?

Accepted Answer

Answer reason: Chronic typhoid carriage occurs when Salmonella Typhi persists in the gallbladder, often on gallstones and biliary epithelium where biofilms protect it from immune clearance. Organisms are shed intermittently via bile into the intestine, leading to prolonged fecal excretion. The liver, pancreas, and kidneys are not typical reservoirs for chronic carriage.

Question 43

Bacteria belong to which kingdom?

Accepted Answer

Answer reason: In the five-kingdom classification, all prokaryotic organisms lacking a true nucleus and membrane-bound organelles are placed in Kingdom Monera. Bacteria are prokaryotes, fitting this category. Protista, Fungi, and Plantae are eukaryotic kingdoms and therefore do not include bacteria.

Question 44

Chicken pox is caused by?

Accepted Answer

Answer reason: Chickenpox is caused by the varicella-zoster virus, a DNA herpesvirus. It presents with a pruritic vesicular rash, fever, and malaise, and spreads via respiratory droplets and direct contact with lesions. Bacteria, fungi, and parasites do not cause this characteristic illness.

Question 45

Widal test is used to detect?

Accepted Answer

Answer reason: The Widal test is a serologic tube agglutination test that detects antibodies (O and H agglutinins) against Salmonella enterica serovars Typhi and Paratyphi. A significant or fourfold rise in titer supports the diagnosis of typhoid fever, especially after the first week of illness. While cultures are definitive, Widal is used in resource-limited settings as supportive evidence. It is not used for malaria, tuberculosis, or cholera.

Question 46

Most common STD worldwide is?

Accepted Answer

Answer reason: Among common sexually transmitted infections, Chlamydia trachomatis accounts for the highest global prevalence of curable STIs. Many infections are asymptomatic, facilitating ongoing transmission and high case numbers. HIV and syphilis have lower prevalence compared with chlamydia, and gonorrhea is less common than chlamydia worldwide.

Question 47

The dengue mosquito bites?

Accepted Answer

Answer reason: The dengue vector Aedes aegypti is a day-biting mosquito. Its peak feeding occurs in the early morning and late afternoon, leading to most dengue transmission during daylight hours. It is not restricted to only morning or only evening and is less active at night.

Question 48

What is the usual incubation period of Hepatitis A?

Accepted Answer

Answer reason: Hepatitis A virus has an incubation period that averages about 28 days, with a commonly cited range of 15–50 days. This reflects the time from fecal–oral exposure to onset of symptoms such as jaundice and malaise. Shorter periods like 1–2 days are typical of many respiratory viruses, while the longer periods listed fit other hepatitides or chronic infections. Therefore, 15–50 days is the correct range.

Question 49

When are patients with acute viral coryza most contagious?

Accepted Answer

Answer reason: Acute viral coryza (common cold), commonly due to rhinoviruses and other respiratory viruses, has peak viral shedding at the onset of symptoms. Transmission efficiency is highest during the first 48–72 hours of illness and then declines as the immune response increases. Therefore, patients are most contagious in the first 2–3 days after symptoms appear.

Question 50

Which body fluid has highest concentration of HIV?

Accepted Answer

Answer reason: HIV viral load is highest in blood, making it the primary medium for transmission via percutaneous or mucosal exposures. Saliva, sweat, and tears contain very low levels of virus and have inhibitory factors (e.g., enzymes in saliva), so transmission through these fluids is extremely rare and not epidemiologically significant. Therefore, among the listed fluids, blood has the highest concentration of HIV.

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