No. To
[ 22 ]
Appendix No. 6.
HONGKONG, 17th November, 1900.
SIR, We have the honour to report for the information of His Excellency the Governor that in accordance with His Excellency's instructions we proceeded to Táipó on the afternoon of Monday, 12th instant, for the purpose of enquiring into the causation of the marked prevalence of Malarial Fever there recently; and returned to Hongkong on Wednesday evening.
2. We desire to acknowledge the courteous assistance rendered to us by Mr. MESSER, Mr. WOOD, Dr. Ho Nai Hor and the police, enabling us to make the most of the short time at our disposal.
3. We already had before us the following statistics as to the prevalence of mosquitoes at Tái- pó during the preceding months :-
Date.
Mosquitoes caught Anopheles.
Culex.
""
September 4, 19,
50
49
11
7
>>
24,
62
23
. 39
October
50
5
45
17,
37
33
"
29
21,
44
27
November 12,
55
33
22
42
17
Total,
309
126
183
i.e., Anopheles.....40 %
Culex 60%
By special request there had been no selection of specimens, all those caught on the various dates named being sent for examination and classification; so that during the period between 4th September and the date of our visit 40% may be taken as the actual average prevalence of the Anopheles among all mosquitoes found. The species is a larger one than that most common iù Hongkong, and we identify it as Anopheles Sinensis.
4. From police records placed at our disposal we ascertained that the cases of Fever among the police during the last twelve months have becu as follows:-
وو
November, 1899, December, January, 1900, February, March, April, May
5
1
©2-22ONORGE.
وو
2 Europeans, 7 Indians.
"
"
"
15
"
J
""
"
"
"}
17
>>
"
""
"
June,
5
"}
"
July,
13
3 Europeans, 22 Indians.
August,
27
""
"}
**
September,
28
35
"
"
October, November,
17
>"
»
"J
1
14 13
It is noteworthy, on comparison of this with the preceding table, that while the enumeration of Anopheles rises to 60% of all mosquitoes found at the date of our arrival at Táipó, Malarial Fever had almost disappeared. We attribute this rapid fall in the number of cases of fever during the period of the cutting of the second rice-crop, which we found in progress, and during which the previous experience of the police would have led to the expectation of an increased number of cases of Malaria, chiefly to the recent adoption of vigorous prophylactic medication with Quinine on two days successively at intervals of seven days.
5. We made careful search in all directions around the Government buildings and matsheds for breeding-places of Anopheles, our investigation extending over the adjoining paddy-fields as far as the river to the north, to the villages on the west, and across the river and up certain of the ravines beyond it on the south side.
*
We show the results of our search on the accompanying rough sketch-map, the places where Anopheles larvæ were found being indicated with red ink. We believe that the negative results in the paddy-fields and in the whole river valley to the south were probably chiefly due to the washing away of larvæ by the rain-storm which accompanied the typhoon three days before our visit. The positions in which larva were actually found abundantly were in the narrow ditches around the uppermost paddy-fields, where the rain-washing would be least marked, and in a marshy sluggish stream, into which the paddy fields drain, to the north-west of the Government buildings, where also the disturbance by the storm would be at a minimum.
-
We direct special attention to two important points: (1) that the breeding-pools that proved most resistant to the severe strain of the recent rain-storm, and which even at this late date in the year contain abundant larvae, are within 80 yards from the Police Station and 40 yards from the matshed occupied by the Civil Staff; and (2) that the marshy stream above referred to is a perma nent and prolific breeding-ground.
*Not printed.