The common cold has evaded medical sciences advances for two primary reasons:
(i) The first issue is that the colds are most often caused by a rhinoviruses-a large family of viruses with hundreds of variants. This makes vaccination an impossibility and gives our immune system a challenging task.
(ii) Secondly, these viruses evolve rapidly so even if we could produce vaccines to cover the full spectrum of rhinoviruses, they would quickly become resistant.

(i) Mild tremors to convulsions.
(ii) Severe agitation and fits.
(iii) Depressed mood.
(iv) Anxiety.
(v) Nervousness.
(vi) Restlessness.
(vii) Irritability.
(viii) Insomnia.
(ix) Dryness of throat.

(i) "Wuchereria bancrofti".
(ii) Chronic inflammation of the lymph nodes. Obstruction of lymph in the vessels of the lower limb.
(iii) Transmitted through an agent/vector called Female Culex mosquito.

Blood cells (RBC) get infected :
(i) Atoxin hemozoin and eiythrocytic debris into the blood stream resulting in malarial paroxysms-shivering chills, high fever followed by sweating.
(ii) Fever and chills are caused partly by malarial toxins that induce macrophages to release tumour necrosis factor (TNF\(\alpha\)) and interleukin.

(i) For Diphtheria:
Causal agent: Corynebacterium diphtheria.
Mode of Transmission: Droplet infection through breathing.
Symptoms: Fever, sore throat, hoarseness and difficulty in breathing
(ii) For Typhoid: 
Causal agent: Salmonella typhi
Mode of Transmission: Through contaminated food and water
Symptoms: Headache, abdominal discomfort, fever and diarrhea.

(i) Certain types of leukocytes (WBCs), such as polymorphonuclear leucocytes (PMNL), neutrophils, monocytes, and natural killer cells [NK cells] (a type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes
(ii) Besides the phagocytes there are natural killer cells (NK cells) in the body which kills virus infected and some tumor cells.
(iii) These cells are categorized under the cellular barriers.

In the 1950s, experiments conducted by Porter and Edelman revealed the basic structure of the immunoglobulin.
An antibody molecule is Y shaped structure that comprises of four polypeptide chains, two identical light chains (L) of molecular weight 25,000 Da (approximately 214 amino acids) and two identical heavy chains (H) of molecular weight 50,000 Da (approximately 450 amino acids). The polypeptide chains are linked together by di-sulphide (S-S) bonds. One light chain is attached to each heavy chain and two heavy chains are attached to each other to form a Y shaped structure. Hence, an antibody is represented by H₂L₂.
The heavy chains have a flexible hinge region at their approximate middles.
Each chain (L and H) has two terminals. They are C - terminal (Carboxyl) (or) -COOH and amino or N-terminal (or NH₂). Each chain (L and H) has two regions and they have variable (V) region at one end and a much larger constant (C) region at the other end.
Antibodies responding to different antigens have very different (V) regions but their (C) regions are the same in all antibodies.
In each arm of the monomer antibody, the (V) : regions of the heavy and light chains combine to form an antigen - binding site shaped to 'fit' a specific antigenic determinant.
Consequently each antibody monomer has two such antigen - binding regions.
The (C) regions that forms the stem of the antibody class and serve common functions in all antibodies.
The functions of immunoglobulin are agglutination, precipitation, opsonisation neutralization etc.

(i) The types of barriers which involve macrophages are phagocytic barriers
(ii) It is also known as cellular barriers.
(iii) Certain types of leucocytes (WBCs), such as polymerase nuclear leukocytes (PMNL) : neutrophils, monocytes and natural killer cells (a type of lymphocytes) in the blood as well as macrophages in tissues can phagocytose and destroy microbes.