The disease has an incubation period of 3-15 days followed by a fever with depression and loss of apettite and increased heart rate. The animal becomes congested with large quantities of mucus, saliva and mucus secretion from the eyes. There is necrosis in and around the mouth. In the final stages, bloody diarrhea, dehydration, and abdominal pain develop followed by collapse and death.

As with many other highly infectious disease of animals, slaughter and destruction of carcasses and strict quarantine are the primary responses.

A highly effective vaccine is available.

The disease first presents itself with fever, headache, vomiting and conjunctivitis. It progresses to neurological symptoms (confusion, disorientation etc.) and muscle weakness. About one-third of cases enter a coma and a third of them die. Survivors show neurological and psychological after effects (sequelae) in about 20% of cases.

The disease is transmitted by mosquitoes and was found in sentinel mice and in local wild birds that seem to be the natural host and reservoir.

The disease is of concern because it is rapidly developing, disabling, killing, and poorly characterized.

The virus is one of those that Iraq is believed to have looked into as a weapon. This is quite ingenious as it is widespread, easily caught, disabling without being lethal and highly deniable. It would be particularly effective against troops in the field away from safe water supplies and on tight water budgets. Diarrhea is also a genuine public health problem in the Middle East and it could be studied without comment.

• Gastroenteritis
• Paratyphoid
• Paratyphoid fever

• Bacterium prodigiosus
• Chromobacterium prodigiosum
• Micrococcus prodigiosus
• SM

There are two broad classes of S. marcescens: those that grow well at low temperatures and that produce a red pigment (prodigiosin) and those that grow at 37°C and that do not produce pigment. The pigmented strains are not pathogenic and one of these was used as a simulant because it can be easily spotted on plate cultures and identified by a number of simple tests.

There were a number of outbreaks of Serratia infection in and around areas where tests were conducted and a number of investigations were made into a possible link. The strain used had been very well characterized by standard procedures (serology and bacteriophage typing) and it was never recovered from any of the suspect cases. There was a great of not entirely undeserved criticism for continuing to use the agent after concerns had been raised.

• Goat pox virus
• Monkeypox
• Variola(smallpox)

Animals that survive the disease also become resistant to Goat pox virus.

• Japanese encephalitis virus
• Murray Valley encephalitis virus
• West Nile virus

In clinically significant cases, the fever and headache are more severe and the victim may experience a stiff neck, stupor, disorientation, tremors, convulsion, coma and spastic paralysis (typified by loss of control and muscle spasms.)

Fatality rate is 3% in young adults and can reach 30% in the aged. There is no vaccine or specific treatment. Mosquito control is the primary response.

Biochemical regulator

Click on thethumbnail to see a structure diagram for substance P

Biologically, substance P is a member of a class of peptides called tachykinins that play a role in converting a nerve impulse into a biological event. Tachykinins act in may systems so exposure to relatively high concentrations can throw a victim into disarray.

Substance P has two major activities that would be incapacitating:

Vasodilation

Substance P stimulates the opening of blood vessels and on a whole body level this can lead to a drop in blood pressure resulting in dizziness or collapse.

Bronchoconstriction

Substance P stimulates constriction of the airways leading to a shortness of breath or even asphyxiation.