RABIES ILLNESS
| Incubation: | Several days – 19 yrs | |
| Avg: | First 90d (75%) | |
| < 30d (25%) | ||
| 30 – 90d (50%) | ||
| 90d – 12mo. (20%) | ||
| > 1yr (5%) | ||
| Initial Symptoms: | ||
| Systemic: | As with other viral infections: | Fever |
| (4 – 10 days) | H/A | |
| Malaise | ||
| Upper respiratory/GI sx’s | ||
| Myoedema (mounding of part of muscle after | ||
| reflex hammer strike, extincting in seconds) | ||
| Neuro: | Personality/Cognitive Changes | |||||
| Pain/Paresthesias – exposure site | ||||||
| 2 – 14 days to coma | ||||||
| “Furious” Rabies (80% of cases): | Hydrophobia | |||||
| Aerophobia | ||||||
| Delirium | ||||||
| Agitation | ||||||
| Hydrophobia: exaggerated irritant reflex of the respiratory tract (? Nucleus ambiguous) | ||||||
| Description by Sir William Gowers (excerpts), | ||||||
| Discomfort about throat | ||||||
| Choking sensation | ||||||
| Liquid dysphagia (pharynx spasm spreading to muscles) | ||||||
| Short, quick inspiration; a “catch in the breath” | ||||||
| Strong inspiratory effort with accessory respiratory muscles and mouth | ||||||
| angles outward and shoulders raised | ||||||
| Increasing respiratory/pharynx spasm severity and sensitivity (to provoke); | ||||||
| brought on by mere water contact on lips or a draught of air on hyperesthetic skin | ||||||
| Inability to swallow saliva, abundant and viscid (hanging on mouth) | ||||||
| Vomiting common | ||||||
| Attacks very distressing to patient – increasing attacks, such that even | ||||||
| sight of water causes attack | ||||||
| Strong light or visual image (mirror reflection) provoking attacks | ||||||
| Sufferer’s horror/dread of attack becomes intense | ||||||
| Disordered swallowing causes mental disturbance and other extensive | ||||||
| muscle spasms | ||||||
| Spasms first only with muscles of deglutition and respiration, then to other | ||||||
| muscles and finally spasmodic paroxysms (convulsive) at first respiratory, | ||||||
| then general (tetanoid rigidity/opisthotonus) | ||||||
| Delusions/Wild Delirium – mental derangement, worst during paroxysms, | ||||||
| and frenzied patient spits saliva at others and attempts to bite; strange | ||||||
| dog-like barking | ||||||
| Other Episodic Neuro Phenomena: | Hyperactivity | |||||
| Seizures | ||||||
| Aerophobia | ||||||
| Hyperventilation, then periodic/ataxic | ||||||
| breathing, then apnea | ||||||
| SIADH (Syndrome of Inappropriate Anti Diuretic Hormone) | ||||||
| Apnea | ||||||
| Other: | Cardiac arrhythmias | |||||
| Autonomic dysfunction | ||||||
| – piloerection | ||||||
| – sweats | ||||||
| – pupillary dysfunction | ||||||
| – increased salivation | ||||||
| – priapism/ejaculation | ||||||
| Death: Within 1-2 weeks of coma FR, with strong medical support, passes through PR phase | ||||||
| Paralytic(Dumb) Rabies (PR) | ||
| – No hydrophobia, aerophobia, hyperactivity, or seizures | ||
| Initial: | Ascending paralysis (like Guillain-Barré syndrome) or symmetric quadriparesis | |
| Weakness may be most severe in bitten limb. | ||
| Later: | Meningeal signs (sometimes prominent) | |
| Confusion | ||
| Coma | ||
| Death usually due to myocarditis with arrhythmias or CHF | ||
| Total time to death from illness onset averages 0 – 14 days | ||