626 RESEARCH IN PROGRESS

The association between M. perstans and a higher CD4 + T lymphocyte count is unexpected.

[This poster presentation was highly commended.]

Ret inopathy in G a m b i a n chi ldren a d m i t t e d to hospi ta l wi th malar ia

M. J. Burton 1'2, O. Nyong 'o ~, K. J. Bur ton 1, W. John 1, E. I n k o o m 1, M. P inder 1, T. Corrah 1, G. J. Johnson 4 and R. L. Bailey 1'2 1Medical Research Council Laboratories, Fajara, P.O. Box 273, The Gambia; 2London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; 3University of Califor- nia, San Francisco, USA; 4International Centre for Eye Health, Institute of Ophthalmology, London, UK

A retinopathy characterized by retinal haemorrhages, whitening, vascular abnormalities, and papilloedema has previously been described in African children with established cerebral malaria. In this study the preva- lence, pattern, clinical significance, and accessibility to clinical examination of this retinopathy are described in 106 Gambian children admitted consecutively to hospi- tal with severe malaria, including 6 with established cerebral malaria. Retinopathy was found in 4/6 (66%) of children with cerebral malaria and in 7/82 (8.5%) of those with severe, non-cerebral malaria. Both retinal haemorrhages and whitening were observed. The pre- valence of retinopathy increased with decreasing admis- sion Blantyre Coma Score. Children with retinopathy had an increased risk of convulsions during the subse- quent 2 d (relative r i sk= 4.84, 95% CI 1.25-18.7, P = 0.047), and such convulsions occurred more com- monly with lower admission Blantyre Coma Scores. Analysis suggested, but did not definitively establish, the independent predictive value of retinopathy for subsequent convulsions. Direct ophthalmoscopy by an ophthalmologist following pupil dilation identified 72% of eyes in which retinopathy was demonstrated by indirect ophthalmoscopy. The admitting doctors cor- rectly identified retinopathy in 37% of the abnormal eyes they examined. Retinopathy can be detected with a direct ophthalmoscope by doctors without formal ophthalmological training, particularly if the pupils are dilated first.

Molecu lar studies o f spec iat ion in the Anopheles g a m b l a e c o m p l e x

Kwang Shik Choi Liverpool School of Tropical Medi- cine, Pembroke Place, Liverpool L3 5QA, UK

Many important malaria vector species belong to species complexes, the identification of which is based increasingly on DNA sequence differences. This study focuses on sequence divergence at loci on the X chromosome. Using the Anopheles gambiae genome database, potentially divergent regions have been iden- tified and selected loci sequenced, and, for microsatel- lite loci, allele frequencies calculated. Genetic differences between the molecular M and S forms of A. gambiae have been demonstrated at X-linked loci. Al- lele frequencies in M and S forms from Angola and Mozambique were not different at 2 microsatellite loci, AGXH81 and AGXH71 l/w, within the Xag inversion. However, AGXH678, outside the Xag inversion,

s h o w e d significantly different allele frequencies be- tween the M and S forms from Angola and frequencies were different in the S form from Angola and Mozam- bique. There was one fixed nucleotide difference in the D3 region of the rDNA 28S gene between A. arabiensis and A. gambiae but none between the M and S forms of A. gambiae. Similar techniques are being used to look at population subdivision in A. arabiensis. These studies of molecular imprints of the speciation process should

result in sensitive new tools to investigate speciation in anopheline vectors.

Bit ing t i m e s o f malar ia vectors in C a m b o d i a

Mary Cooke and Sok Vanne London School of Hygiene and Tropical Medicine, Keppel Street, London [VICE 7HT, UK

The province of Mondulkiri in eastern Cambodia suffers from a high transmission of Plasmodium falcipar- um and P. vivax compared with that of other lowland regions, despite a national insecticide-treated bednet (ITN) campaign. CDC light traps set beside occupied untreated bednets were used to collect Anopheles mos- quitoes. The traps were visited 4 times during the night so that the catch in the hours after dusk and before dawn, when many people are out of bed, could be distinguished from the middle quarters of the night when nearly everyone would be in bed and protected by an ITN. The mosquitoes caught in the monsoon season were predominantly of the A. minimus group, with some of the A. dirus complex, A. maculatus, A. actonius, and A. philippinensis. All have been previously identified as malaria vectors in the region. The catch declined progressively from the first to the fourth quar- ter of the night and 40-60% of those malaria vectors caught were at times when many people are out of bed. Assuming that the time of trapping mosquitoes corre- sponds with when they would have bitten, these data suggest that ITNs cannot be relied on to offer efficient protection from this vector population.

Indoor air pol lut ion due to b i o m a s s fuels in north India

Mukesh Dheran i Department of EPH, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK

A cross-sectional study was conducted to estimate the indoor air pollution caused mainly by biomass fuels in 110 randomly selected households from 11 villages in north India.

The majority of the households (82%) have a com- pletely open kitchen. Cattle dung (mean use 4 + 2 kg) is almost invariably (99%) used as a fuel by households. The most common stove type is mud stone without a chimney (95%). Nearly 40% of households have liquid petroleum gas stoves which are infrequently used. The average particulate matter (PMs) in the cooking area was 4800 -4- 3200 ~g/m 3 (geometric mean = 3800 [lg/m 3) during cooking. The living room PM5 was 450 -t- 280 [l,g/m 3 (geometric mean = 390 ~g/m 3) measured for 24 h. Linear regression suggests that each fuel (dung, wood and crop residues) is strongly asso- ciated with air pollution. Health hazards are known to be associated with indoor air pollution and their levels in north India are far higher than those reported in south India. The main reason could be the use of cattle dung which is ubiquitous in north India. Cleaner fuels and stoves are available in many houses but their utility is very limited. The limitations on the usage of cleaner fuels needs investigation.

Dis tr ibut ion o f the m o l e c u l a r forms o f Anopheles gambiae and pyrethro id res i s tance in southern Ghana

A. Egy ir -Yawson 1, P. J. McCalP , M. D. Wi l son z and M. J. Donne l ly 1 1Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; 2Noguchi Memorial Institute for Medical Research, Univer- sity of Ghana, Legon, Ghana

Following the Roll Back Malaria (RBM) initiative,