Table 1. Characteristics of intervention sites and potential determinants of epidemics*.
| Characteristic/ determinant | Kisii/Gucha, Kenya | Kayanza, Burundi | Aweil East, southern Sudan | Gutten, Ethiopia | Damot Gale, Ethiopia |
|---|---|---|---|---|---|
| Epidemic period (no. weeks) | May–August 1999 (15) | September 2000–May 2001 (36) | June–November 2003 (22) | July 2003–February 2004 (33) | July 2003–January 2004 (30) |
| Population | 956,000 | 578,000 | 307,000 | 44,000 | 287,000 |
| Altitude (m) | 1,200–2,200 | 1,400–1,750 | 430 | 1,700 | 1,600–2,100 |
| Malaria vectors | Anopheles funestus (constant), A. gambiae sensu lato (seasonal) | A. arabiensis (95%), A. funestus (5%) | Not available (A. gambiae sensu lato presumed) | A. arabiensis | A. arabiensis |
| Malaria species (nonepidemic months) | Plasmodium falciparum (>90%) | P. falciparum (>90%) | P. falciparum (>95%) | P. falciparum (≈25%), P. vivax (≈75%) | P. falciparum (≈60%), P. vivax (≈40%) |
| Temperature anomalies | Above average in 3 preepidemic months | None apparent | Maximum LST strongly below average during epidemic | None apparent | None apparent |
| Rainfall anomalies | Heavy rainfall in preepidemic rainy season after drought in previous rainy season | Heavy rainfall 5 and 3 months before epidemic, drought 2 years before epidemic but not in preepidemic year | Below average rainfall in 3 preepidemic years, above average in 2 preepidemic months | Below average rainfall in 2 preepidemic and epidemic years but heavy rainfall in preepidemic month | Below average rainfall in 2 preepidemic and epidemic years but heavy rainfall in 3 preepidemic months |
| Land pattern changes | None reported | Creation of rice paddies and fish ponds | Widespread flooding | Creation of water ponds | None reported |
| Political instability | None | Armed conflict | Tenuous ceasefire | Inactive insurgency | Inactive insurgency |
| Population movement | None | Forced relocation | Seminomadic, returnees from north Sudan | Government resettlement schemes | Government resettlement schemes |
| Global acute malnutrition† | Not available | 10%–15% | 25% | Not available (probably >5%) | 28% |
| Drug resistance (in vivo failure rates) | CQ 24%–87% (neighboring districts), SP 10% (13) | CQ 100%, SP 54.2%, CQ+SP 42.0% (9) | CQ 63%, SP 3% (14)‡ | SP 78.0% (15) | SP 68.1% (neighboring zone) (15) |
*LST, land surface temperature; CQ, chloroquine; SP, sulfadoxine-pyrimethamine. †Among children <5 y of age; malnutrition rates >15% denote a serious situation; values are provided for 2 months before the epidemic. ‡Percentages refer to the frequency of single Pfcrt mutations and triple Dhfr mutations in the P. falciparum genome of outpatients sampled in Aweil East. These mutations are predictive of in vivo CQ and SP failure rates, respectively.