H.—3l.

APPENDIX.

INVESTIGATION INTO CASES OF TYPHOID FEVER IN HAWKE'S BAY CAUSED THROUGH CONSUMPTION OF POLLUTED SHELL-FISH. By Dr. F. S. Maclean, Medical Officer of Health. The reported cases of typhoid in Hawke's Bay for the last four years are as follow : — 1929 (22 cases) .. 12 Europeans. 1931 (20 cases) .. 4 Europeans. 9 Maoris. 16 Maoris. 1 Tonga n. 1930 (8 cases) .. 2 Europeans. 1932 (14 cases) .. 3 Europeans. 6 Maoris. |. 11 Maoris. Of the twenty-seven Maori cases in 1931 and 1932, twenty-six occurred between February, 1931, and July, 1932. The history of several of the eases suggested the possibility of infection arising from the consumption of polluted shell-fish from Westshore, and during the year the matter was fully investigated with important results. Statistically, the evidence tracing the infection to polluted shell-fish might be discounted by the suggestion that most Maoris in Hawke's Bay were in the habit of eating shell-fish, and that therefore I he majority of those contracting typhoid fever would almost certainly have done so in the same way that they would have eaten bread or potatoes. If, however, one could prove that the shell-fish were polluted with sewage, and could quote specific cases in which mussels or pipis were eaten within the period of incubation, one would seem to be on more certain ground. Before the earthquake of February, 1931, mussels and pipis were taken from different places within the inner harbour, which was then tidal, anil the bulk of the Napier sewage was discharged at the harbour entrance and carried well out to sea on the outgoing tide. The amount of tidal water available to carry the sewage out to sea was very considerable. It is probable that even then there was some pollution of shell-fish, and possibly some of the enteric fever was caused in this way. A case in point is that of T. R., of Waimarama, a Maori, who ate mussels on 9th January, 1930, and became ill with typhoid fever on 20th January. J. T., of Moteo Pa, who became ill the following month, also gave a history of having eaten mussels from the inner harbour. In November, 1927, ten Maoris suffering from typhoid fever were admitted to King George V Hospital, Rotorua. The outbreak was traced to a tangi held about a month previously at Oruanui at which there had been consumed a lorry load of mussels brought from Westshore. The mussels were gathered from the vicinity of the old bridge and were eaten raw or partially cooked. Those eating them felt sick after the feast, and became ill with typhoid fever two weeks later. The earthquake so raised the floor of the lagoon that tidal water ceased to enter it, and the water remaining gradually became first brackish and then fresh. The result of this was two-fold ; there was no great body of tidal water to carry away the sewage, and most of the pipis and mussels inside the harbour entrance died out. A few pipis survived just inside the entrance, but they were buried in silt during a flood in May, 1932. At the present time the only shell-fish remaining in this locality are the mussels on a reef in the open sea a few chains to the west of the western mole, and about a quarter of a mile from the sewer outfall. There may be others on the rocks along the foreshore, but those mentioned are the ones from which the supply has mainly been taken since the earthquake. To any one looking over the harbour from the hills there is visual evidence that sewage remains round the harbour entrance, and discolours the water in the vicinity. In May, 1932, a number of mussels were obtained from this reef and examined bacteriologically. Five mussels were opened and the liquor from shell and body extracted. Five others were " cooked " in the Maori fashion by heating in water until the shells opened. Their liquor was likewise examined with the following results : — In each case five McConkey tubes were inoculated with 1 c.c. of liquor, five with 0-1 c.c, and five with 0-01 c.c. In the case of the raw mussels four tubes out of five showed the presence of B. coli in 0-01 c.c. of the liquor, while in the case of the " cooked " mussels three tubes out of five showed the presence of B. coli in 0-01 c.c. The evidence is fairly conclusive, therefore, that shell-fish from this locality may be heavily polluted, and any one eating three or four raw mussels at a sitting might easily consume also a large number of feecal organisms. Maoris commonly eat mussels and pipis in one of four ways : raw, scalded, fried, or cooked thoroughly, and pickled ; and infection from raw or scalded shell-fish would appear to be probable. In the following cases evidence of infection in this manner is forthcoming : — March, 1932, Mrs. D. (European) living at Westshore ate some mussels and was taken ill within three weeks. March, 1932, Mr. N. and Mrs. N. (Maoris) attended at wedding feast at Tahoraiti Pa, Dannevirke, on 15th February, and ate raw mussels obtained from Westshore. Mr. N. became ill on 2nd March and his wife on 3rd March. Other guests at the feast ate the mussels cooked.

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