Which of the following is an example of a toxoid vaccine?

The correct answer is B, bacteria. Typhoid is caused by the bacterium Salmonella Typhi, which spreads through food and water contaminated with human waste, and it is prevented both by sanitation and by the typhoid conjugate vaccine. Option A is wrong; the viral diseases of this group are polio, measles, hepatitis, dengue and influenza, not typhoid, and candidates choose it because typhoid produces a long fever much like a viral one. Option C is wrong because fungi cause surface infections such as ringworm and athlete foot rather than a systemic fever of this kind. Option D is wrong; the protozoan diseases are malaria, kala azar and amoebic dysentery. The safest way to hold this group is to memorise the bacterial list as typhoid, tuberculosis, cholera, tetanus, diphtheria, leprosy and plague, since that list answers several questions at once.

The correct answer is C, protozoa. Malaria is caused by the protozoan Plasmodium and carried by the female Anopheles mosquito, and kala azar, also called visceral leishmaniasis, is caused by the protozoan Leishmania donovani and carried by the sandfly. Both are handled by the national centre for vector borne diseases, which is why they appear together in papers. Option A is wrong because the bacterial group holds typhoid, tuberculosis, cholera and plague. Option B is wrong; fungal infections are of the skin, hair and nails and none of them is spread by a mosquito or a sandfly. Option D is wrong although it is the commonest error, since dengue, chikungunya and Japanese encephalitis are indeed viral and are also spread by insects, so candidates assume every insect borne disease is a virus. Fix malaria and kala azar firmly on the protozoan side.

The correct answer is B, swine flu. Swine flu is an influenza infection of the type first recognised in pigs, and the name itself records the animal in which the virus circulates before it passes to people; once it is in a human population it spreads from person to person by droplets. Option A is wrong because Nipah virus infection is linked to fruit bats, which contaminate date palm sap and fruit, although pigs did act as intermediate hosts in an early outbreak in South East Asia. Option C is wrong; Zika is a virus carried by Aedes mosquitoes, the same group that carries dengue and chikungunya. Option D is wrong because plague is a bacterial disease carried by the flea of the rat. Learn the animal attached to each name, since the paper may ask for the animal, the vector or the kind of germ.

The correct answer is B, Edward Jenner, against smallpox. In 1796 Jenner used material from cowpox, a mild disease of cattle, to protect a boy against smallpox, and the word vaccine itself comes from vacca, the Latin for cow. Option A is wrong in its order rather than in its facts: Louis Pasteur did make a rabies vaccine, but in 1885, almost ninety years later, and he named the method vaccination in honour of Jenner. Option C is wrong because Robert Koch identified the tuberculosis bacterium in 1882 and did not make its vaccine; the BCG vaccine was developed later by Calmette and Guerin, whose names it carries. Option D is wrong; Alexander Fleming discovered penicillin, an antibiotic and not a vaccine, in 1928. Keep the triple of Jenner with 1796, Pasteur with 1885 and Fleming with 1928.

The correct answer is A, tuberculosis. BCG stands for Bacillus Calmette Guerin, a live attenuated strain of a bovine tuberculosis bacterium, and it is given at or soon after birth under the Universal Immunization Programme to guard against severe forms of childhood tuberculosis. Option B is wrong because tetanus is prevented by a toxoid, a toxin made harmless, given in the childhood series and again after a wound. Option C is wrong; hepatitis B is prevented by a recombinant subunit vaccine that carries only one surface protein of the virus, and a birth dose of it is also part of the programme, which is why it is a strong distractor. Option D is wrong because measles is prevented by a live attenuated viral vaccine given later in infancy, usually combined with rubella. Learn each vaccine with its type as well as its disease.