Since 1992 an effective malaria eradication program in Oman has reduced the incidence of autochthonous malaria from 8.30 per 10,000 to 0.28 per 10,000. This success exposed a previously unrecognized problem of drug resistant Plasmodium falciparum in Omanis returning from areas of Zanzibar and East Africa settled by Omanis. In order to prevent severe malaria and to safeguard Oman from introduced transmission all air passengers arriving in Oman from East Africa are first examined in the airport with a thick blood film (TBF) and followed with active case detection (ACD) involving weekly TBF for four weeks. We evaluated the cost-effectiveness of the current program and of replacing the TBF with a new rapid test, the Immunochromotographic Test (ICT).
Methodology
We computed incidence rates for East African falciparum malaria (EAFM) from malaria surveillance data including airport screening from 1995 to 1997. We computed the costs of screening, malaria treatment, and outbreak containment from the Ministry of Health perspective. From a decision tree we estimated costs for the current program, cost for replacement of the TBF with ICT, and costs for no program.
Results
Under the current program 1026 (3.4%) of 30,390 arrivals had EAFM. These included 612 detected in the airport, 54 from weekly ACD and 360 more through passive case detection (PCD) at hospitals and clinics. Three patients died and three more initiated local malaria outbreaks. The existing screening program gave a total cost of $784,000 including treatment and outbreak costs. Compared with no program the average cost per severe (required intensive care) case averted was $33,580 and per outbreak averted was $80,590. Substituting the ICT yielded estimates of $655,800 for total cost with $22,000 per severe case averted and $57,500 per outbreak averted. Screening with ICT without ACD gave a total cost of $365,900 with an average savings of $ 2,151 per severe case averted and $6,430 per outbreak averted. Elimination of ACD would add only 3 severe cases and 1 outbreak when compared to the current program.
Conclusion
The current screening program with either TBF or ICT is an expensive alternative to PCD with hospital treatment and outbreak containment. However, using the ICT at the airport without ACD follow-up provides a cost savings with only a minor decrease in the effectiveness relative to the current program.