1. Dengue Fever in Australia is undoubtedly an introduced disease. It has been existent from time to time in epidemic form since 1885.
2. The clinical description of the disease agrees with that of the Dengue described in text-books, the only departure noted being the distinct tendency to a relatively, and sometimes absolutely, slow pulse rate as compared with the temperature.
3. It is possible that under the single term “Dengue” more than one disease is at present included.
4. Epidemic Dengue in Australia is approximately co-extensive with the known distribution of Stegomyia fasciata. It does not extend beyond the area in which this mosquito is prevalent.
5. Stegomyia fasciata mosquitoes caught in a dengue infected district in the surroundings of cases of the disease, and some of them known to have fed on a dengue patient on the first and second days of his illness, transported to a non-dengue district, reproduced the disease in four out of seven persons on whom biting experiments were conducted.
6. Blood taken from three of these four cases reproduced the disease when injected into further persons. The blood of one case was not tested.
7. The incubation period of the four cases was found to be possibly between five and nine and a half days, probably between six and a half and nine and a half days, counting from the bitings to the definite onsets.
8. No known case of contagion occurred from any of the above four cases.
9. No evidence was obtained from two cases, one of which was heavily and repeatedly bitten with Culex fatigans, that Culex fatigans is capable of acting as a transmitter of dengue fever.
10. The blood of patients suffering from an attack of dengue can reproduce the disease when inoculated subcutaneously into healthy persons.
11. The disease thus inoculated is typical in every way of dengue fever naturally contracted. The inoculated disease may or may not shew marked skin rashes and double phases in the temperature charts, and presents a relatively and sometimes absolutely slow pulse; such variations occur in the natural disease. The incubation period of the inoculated disease varies from five to nine days corresponding with the incubation period of the mosquito-transmitted disease.
12. Results of the inoculations shew that:
(a) The virus of dengue is present in the blood as a whole.
(b) The serum of clotted infective blood may contain the virus.
(c) With washed corpuscles one apparently positive result was obtained out of three experiments.
(d) The fluid part of citrated infective blood may contain the virus.
(e) With Pasteur-Chamberland filtrates of infected serum and corpuscles, one positive result was obtained out of five experiments.
In considering these results failure to convey tne disease must not necessarily be interpreted as meaning that the menstruum employed never does contain the virus, as in some of the cases the blood may no longer have been infective at the time at which it was withdrawn.
(f) The presence of the virus in the blood has been demonstrated on the second and third days of the disease. Two experiments made may possibly be interpreted as shewing that infective material may still be present on the eighth day of the disease.
(g) One experiment appears to indicate that the virus is no longer present in the blood on the fourteenth day from' the beginning of the illness.
(h) Immunity to the inoculation of infective blood appears to be complete twenty-four days after recovery from a typical attack of dengue.
(i) Infected blood may maintain its infectivity outside the body if kept in a cool place for seven days at least.
(j) In two instances two individuals inoculated with the same material on the same day exhibited incubation periods practically identical in duration.
(k) The infection of dengue can be conveyed by sub-inoculations from individual to individual at least to the fourth generation without the resultant disease departing from the type of the natural disease.
(I) The disease has not been conveyed by the application of infective serum to a scarified area; nor apparently has it been conveyed by the application of infective material by swabbing to the nostrils.
(m) A very doubtful and probably negative result followed the gargling of the throat with infective material followed by swallowing of the same.
(n) Dengue fever has close analogies with yellow fever.