Malaria control with residual fenitrothion in Central Java, Indonesia: an operational-scale trial using both full and selective coverage treatments.

An operational-scale trial, using residual fenitrothion, for control of malaria was carried out in Central Java, Indonesia, from 1980 to 1982. Two areas, each comprising about 70 km(2) and a population of about 50 000, were treated with fenitrothion (40% water dispersible powder) at a target dosage of 2 g/m(2) for 3 cycles at 6-monthly intervals. One area was treated with full coverage (i.e., the interiors of houses and cattle shelters were sprayed to a height of 3 m) for 2 cycles, followed by a third cycle with selective coverage (i.e., the interiors of houses were sprayed with one 75 cm horizontal swath between 10 cm and 85 cm from the floor while the cattle shelters were sprayed to a height of 3 m). The other area was treated for 3 cycles with only selective coverage. While both treatment methods reduced malaria rates and vector populations to very low levels, the full coverage treatment was more rapidly effective and also reduced the Plasmodium falciparum index. However, the selective coverage treatment was 68% less expensive than full coverage and greatly reduced the degree of cholinesterase depressions among the spraymen. The trial also showed that a dosage of 1 g/m(2) with full coverage was nearly as effective as the 2 g/m(2) dosage.

Rodent and scrub typhus survey in a ricefield at Kramat Tunngak area, Tanjung Priok, Jakarta, Indonesia.

Trapping of small mammals in a ricefield at Kramat Tunggak around Tanjung Priok in Jakarta city, was carried out from July 1977 through June 1978. Of three species of rodents, R.argentiventer was found to be the predominant species in the ricefield. R.r.diardii was an intermittent resident, and the presence of R.norvegicus was interesting observation. S.murinus, a house shrew, was also present. R.argentiventer was the dominant species during the periods when the rice grains were available as a source of food. Infestation with Gamasid mites and non-vector chiggers was found common in all rodent species examined. R. argentiventer was the only species found infested with the classical scrub typhus vector (L. (L.) deliense). The density and mean chigger-load of the scrub typhus vector chiggers were found to be high in stages 4 and 5 of the ricefields when the micro-habitats were favourable. The oriental rat flea (X. cheopis) was found infesting all species of rodents.

Susceptibility to DDT, malathion, fenitrothion and dieldrin of three flea species in the boyolali plague endemic area, Central Java, Indonesia.

Insecticide susceptibility tests with 4% DDT, 0.5% and 5.0% malathion, 1% fenitrothion, and 0.2% dieldrin impregnated papers were carried out with fleas spp. from the Boyolali plague zone. The field flea (Stivalius cognatus) which was highly susceptible to malathion before, has now been found to be resistant to the insecticide, but was found susceptible to the other three insecticides. The oriental rat flea (X. cheopis) which found previously highly resistant to DDT, was now found to be less resistant, and susceptible to other insecticides tested. From preliminary tests with DDT to another field flea (Neopsylla sondiacus), it was found to be susceptible to the insecticide.

A study of small mammals in the Ciloto field station area, West Java, Indonesia, with special reference to vectors of plague and scrub typhus.

From June 1977 to June 1978 a study of smal mammals was carried out in the Ciloto field station area, West Java, Indonesia by the WHO Vector Biology and Control Research Unit-II. The objectives of the investigations were to determine the diversity and density of rodent species, to find potential plague and scrub typhus vectors and to study their host-parasite relationships. In the 13 month period a total of 6 species of murids were identified; two species of campestral rats (R. tiomanicus and R. argentiventer), one species of peri-domestic (R. exulans), one species of domestic (R.r. diardii), and two species of forest rats (R. bartelsii and R. bukit). In addition, three species of insectivores (Suncus murinus, Hylomys suillus and Crocidura monticola), and one species of carnivore were found. Of the three habitats studies (mixed, ricefield and lalang), 10 species of small mammals were found in the mixed while four species of commensal murids were found in both the ricefield and the lalang. Of the four commensal murid species R. exulans had the highest density. R. tiomanicus was common but not abundant, and least common was R. argentiventer. R.r. diardii was occasionally found in the field. The mean litter size of gravid R. tiomanicus was 7.1, R. exulans 4.3, R. argentiventer 7.5 and R.r. diardii 9. Male R. tiomanicus, R. argentiventer and R.r. diardii with spermatozoa present in animals over 55 gm. Animals of less than 50 gm had no sperm. In R. exulans spermatozoa were present in specimens weighing 24-66 gm. No sperm were detected in those below 20 gm. The flea index of Xenopsylla cheopis and Stivalius cognatus as determined for R. tiomanicus was 0.3 and 2.3;l for R.r. diardii 2.2 and 1.7; for R. exulans 0.3 and 0.5; and for R. argentiventer 0.4 and 1.7 respectively. S. cognatus had a significantly higher density than X. cheopis among the campestral and peridomestic rats, but the density of X. cheopis was significantly in the domestic rat. Overall infestation rates were equally high in both mixed and lalang habitats, but low in the ricefield. Flea indices were highest in the mixed habitat, lower in lalang, and lowest in ricefield. The putative vector of scrub typhus (Leptotrombidium (L.) deliense) was quite prevalent on campestral rats, less so on domestic ones and least on peridomestic. Overall infestation rates were equally high in both mixed and lalang habitats and low in the ricefield. Chiggers load per animal was significantly higher in the mixed habitat, lower in lalang and lowest in the ricefield.