Table 1 Quantitative assessment of imported malaria from mainland Tanzania (Five Zantel regions: Arusha, Dar es Salam, Dodoma, Mbeya and Mwanza) to Zanzibar (Pemba and Unguja).δr and δv respectively represents the total number of imported infections brought to Zanzibar by residents or visitors infected on mainland Tanzania (importation rate) with Tr the median time spent by residents on mainland Tanzania and Tv the median time spent by visitors on Zanzibar; Nv represents the total number of visitors travelling monthly to Zanzibar; representzs visitor net importation rate, the number of infected visitors weighed by the duration of the trip, Tv , relatively to the duration of infection. The risk of infection is calculated with risk estimates from the main city or from the rest of the region of origin on mainland Tanzania.

From: Travel risk, malaria importation and malaria transmission in Zanzibar

  Regions Residents Visitors Ratio Residents Visitors
   δr (region) δr (city) Tr(days) Nv (ferry) δv (region) δv (city) (city) (region) Tv (days) (region) (city)
Imported malaria per month (absolute number) Arusha 0.2 0.1 8 232 4.2 2.1 0.3 0.2 12 0.7 0.5
  Dar es Salaam 479 48.2 6 13990 648.1 592.3 47.8 66.4 13 10.0 0.7
  Dodoma 6.8 3.9 6 301 49.5 63.5 3.2 6 13 2.1 0.7
  Mbeya 8 2.5 8 70 12.5 19.1 0.9 1.5 11 8.0 1.7
  Mwanza 2.9 2.7 10 78 17.1 31.7 1.2 3.3 21 2.4 0.8
  Mainland Tanzania 496.9 57.4 6 14671 731.4 708.7 53.4 77.4 13 9.3 0.7
Imported malaria per year per 1,000 Mainland Tanzania 5.96 0.69    8.78 8.50 0.64 0.93   9.3 0.7