COLLECTIONS IN MALAYA 
19 
secondary vegetation. There were signs of terracing in places, with occasional etiolated 
pineapple plants hidden in the bracken. The soil on the hillslopes was poor, shallow, and 
lateritised. Geologically, the estate was on mesozoic granites and allied rocks, which tend 
to give an acid soil on weathering. In a few places, some lalang was to be found. 
There had been no record of scrub-typhus from this particular estate, but there had been 
a few post-war cases from the neighbourhood of Kota Tinggi ( ? neglected estates). 
Investigations — Attempts were made to collect potential hosts and estimate their numbers 
and distribution, to collect vector mites from the soil at representative sites, as well as from 
trapped hosts, and, in the event of positive findings, to compare the mite infestation in the 
Estate with that in the forest fringe, and to attempt to recover infection from the mites. 
The following animals were either trapped or recorded by such evidence as droppings, 
footmarks, and noises : elephant ; wild-pig ; tiger ; the darkhanded gibbon ; one Echinosorex 
gymnurus, mconrat ; Suncus murinus , house shrew ; two Rattus exulans , little house-rat ; three 
R. rattus diardii, the Malayan house-rat ; two R. rajah , a spiny rat. 
Hosts : 40 cage-traps, 9 non-return treadle traps, and 50 break-back traps were used for 
a total of 542 trap-nights. The total result was 7 rats and one moonrat ; a trapping rate of 
little over 1 per cent. A total 4I hours of night prowling produced no mammals whatever. 
It was clear that, at the time, the population of small mammals in the area was surprisingly 
low — so low that the rat population may recently have had a violent reduction (“crashed”) 
which would account for the lack of lesser predators also. 
Mites : no trombiculids were found on the 7 rats and the moonrat trapped. There had 
been ample rain — we had indeed been stranded by floods for five days en route to the estate. 
Soil samples, taken from 6 representative sites, were examined by flotation. From over 100 
samples, each approximately a square foot, 3 inches deep, a few trombidiid and bdellid mites, 
and two cyphophthalmids were found, all these being predatory. No trombiculids were found. 
The absence of trombiculids of any species from this large number of selected samples is 
sufficiently unusual to demand explanation. The scarcity of mammal hosts also appeared to 
be remarkable. Had this scarcity obtained throughout the history of the Estate, this would 
suffice to explain the absence of mite colonies in the areas examined, except for the lalang 
patches near habitations. Other factors may have contributed : (1) Lack of introduction of 
mites such as the vector which thrive in the open, because the Estate is somewhat cut off from 
extensive tracts of scrub ; (2) the bracken may have offered very little attraction to small 
mammals ; (3) there may have been undetermined factors in the soil discouraging trombiculid 
nymphs and adults (e.g. high pH, general poverty of soil fauna, number of arthropod predators, 
possible inimical fungi). 
Although it could not be assumed that no foci of scrub-typhus existed on the Estate, it 
was assumed that the risk was so small that no particular preventive steps need be taken. 
Further attempts to trap rodents and shrews during the early days of occupation of this area 
would enable this impression to be strengthened or revised, and this action was recom- 
mended. No cases have been recorded from this estate up to date. 
Reserve near Port Dickson, Negri Sembilan 
(October-November, 1949) 
Description. — The HQ of the Malay Regiment is off the coast road south of Port Dickson, 
Negri Sembilan. There have been cases of scrub-typhus in this area both before and since 
the war. A large military campsite was selected in 1949, covering about 1 square mile, and 
a mile directly inland behind the Malay Regiment HQ and including part of the Sungei Menyala 
Forest Reserve, sections of old rubber plantation, and secondary vegetation. 
MALA YA, No. 26, 1953 
