Area: 1,001 km² (Sao Tome: 836 km² ; Principe: 119 km²) 
Population: 134,785 inhabitants (1998 estimation) 
Capital: Sao Tome
Currency: Dobra 
Official Language: Portuguese 
Surrounding regions: Sao Tome and Principe are two islands, in the Gulf Of Guinea situated off the coast of Cameroon, Equatorial Guinea and Gabon. 

Out of 192 countries, Sao Tome and Principe ranks 108th for life expectancy, 80th for infant mortality, 176th for GNP, 163rd for daily calorie intake, 147th for literacy, 130th for the percentage of children in full-time education (source: Atlas Encyclopédique Mondial, Nathan Ed., Paris 1996, pp.118-119).

Sao Tome and Principe rest on the equator and so the climate is hot and humid. There is however a relative dry season in July and August, whilst the average temperature oscillates between 20 °C (July - August) and 30 °C (January to April).

The oldest facts on malaria in Sao Tome and Principe are no more than twenty years old. 

According to Gérard Martet et al., "Malaria has existed for a very long time on the archipelago. It is characterized by a permanent transmission with seasonal outbreaks that correspond with the end of the rainy season and the start of the dry one (April-May) Another slightly smaller peak occurs from November–December. Transmission decreases with altitude: above 300m of altitude the bio-ecology of the main vector (Anopheles gambiae) and the drop in the density of the human population cause the transmission to decline" (1).

From the 10th to the17th May 1990, a number of tests were run in Sao Tome on 780 children aged from 2 to 9 years old: the prevalence rate of splenomegalies was at 24% and that of hematozoon carriers 41%; this means that Sao Tome can be classified as a meso-endemic zone

Of the 318 positive slides, Plasmodium falciparum was present in 87.4% of cases, Plasmodium  ovale in 11%, Plasmodium  malariae in 1.3% and Plasmodium  vivax only once (0.3%)(1). These figures were not confirmed in 1996 by L.F. Loureiro et al.: who listed 87.2% of infections from Plasmodium  falciparum only, 4.5% from Plasmodium  malariae, 3.5% from Plasmodium  vivax and 4.5% of mixed infection. Plasmodium ovale was not found (3).

According to the “Direction du Plan du Ministère de la Santé”, malaria is the leading cause or morbidity: in effect, 12,413 cases of malaria were reported in 1991, 15,112 in 1992 and 12,514 in 1993, far greater than diarrhea and acute respiratory infections (5). In 1988, 67,162 cases were reported, an incidence rate of 60% (1). Malaria represents 25% of all reported deaths (5).

1. Resistance to chloroquine: 

in vivo:

- The first case of chloroquine failure was reported in 1984 (CEITA J.G.V., in Proceedings of the Conference on Malaria in Africa. Practical Considerations on Malaria Vaccines and Clinical Trials, ed. Buck, A 142-156, Washington DC, U.S.A.I.D.).

- In 1990, a WHO test over 7 days on 58 children showed a chloroquine-resistance rate of 23% (RI: 9% ; RII: 14%) (1).

- The National Anti-Malaria Program for Sao Tome and Principe showed chloroquine to be 75% to 90% effective in vivo (simplified WHO test) in 1995, 75% to 87.5% effective in 1996 and 75% effective in 1997, without however giving any further precision as to the group tested (V. Gil, comm. pers.) 

in vitro: 

Three studies have been published: in 1990, out of 10 strains successfully tested, 9 were chloroquine resistant and one of these at a very high level (1). In 1992-1993, 14 out of 29 isolates (48.3%) were chloroquine resistant (8). In 1994, more than 90% of the 53 isolates tested were chloroquine-resistant (3). 

2. Resistance to other antimalarial drugs:

No resistance to quinine, mefloquine or halofantrine has yet been proved.(1, 3, 8). 

Sao Tome and Principe’s National Anti-Malaria Program showed the sulfadoxine-pyrimethamine combination to be 90% to 99% effective in vivo (Simplified WHO test) in the years 1995, 1996 and 1997, without stating any more information concerning the test group (V. Gil, comm. pers.).

3. Recommendations of the National Anti Malaria Program : 

Since 25th february 2005, the NAMP recommends the artesunate + amodiaquine association as first line treatment and the coartem as second line treatment.

According to J.L. Baptista et al., a mass chemoprophylaxis campaign based upon free handouts of chloroquine was started in 1947. During the 80’s, anti-malaria action consisting in the use of insect sprays and the screening and treating of patients, lead to a significant drop in malaria caused morbidity and also the loss of malaria immunity by the population. It is believed that clinical cases totally disappeared between 1980 and 1983, which lead to the termination of anti-malaria actions in 1984 , and consequently an epidemic revival in 1985-1986 (8).

Today, an active Anti Malaria program exists thanks to the ‘Centre National des Grandes Endémies’. The program employs 21 people and is well equipped. The action plan is built upon the correct treatment of cases, the distribution of treated mosquito nets (less than 1% of the population used them in 1996; 27,000 were installed in 1998), and a chemoprophylaxis for pregnant women and non immune people (V. Gil, comm. pers.).

According to the B.E.H. « Bulletin épidémiologique hebdomadaire » n°24-25 of 14th june 2005, Sao Tome and Principe is classified under chemoresistance group III which implies that travelers to the region should take Mefloquine (Lariam®) or Atovaquone-Proguanil combined treatment.

Individual measures of protection against insect bites should also be taken

(only the first author is mentioned) 

1. MARTET G. et Coll. - Le paludisme en République de Sao tomé et Principe. Evaluation épidémiologique et chimiorésistance de Plasmodium  falciparum. Bull. Soc. Path. Exot. 1991 ; 84: 273-280. 

2. CAMBOURNAC F.J. - Contribution to the history of malaria epidemiology and control in Portugal and some other places. Parassitologia 1994 ; 36: 215-222. 

3. LOUREIRO L.F. et Coll. - Malaria in Sao Tomé and Principe: prevalence and drug-susceptibility. Ann. Trop. Med. Parasitol. 1996 ; 90: 223-224. 

4. RIPERT C. et Coll. - Epidémiologie de certaines endémies parasitaires dans la ville de Guadalupe (République de Sao Tomé et Principe). II. Autres endémies parasitaires. Bull. Soc. Path. Exot. 1996 ; 89: 259-261. 

5. COCHET P., LOUIS F.J. - Sao Tomé e Principe, à la dérive du continent africain. Med. Trop. 1996 ; 56: 21-24. 

6. BAPTISTA J.L. - The history of malaria in Sao Tomé. Considerations on an epidemic. Acta Med. Port. 1996 ; 9: 259-265. 

7. BAPTISTA J.L. et Coll. - Variations dans les taux de lipides plasmatiques en fonction de l'infection à Plasmodium  falciparum à Sao Tomé. Parasite 1996 ; 4: 335-340. 

8. BAPTISTA J.L. et Coll. - Plasmodium  falciparum chloroquine and quinine sensitivity in asymptomatic and symptomatic children in Sao Tomé Island. Trop. Med. Int. Health 1997 ; 2: 582-588. 

9. BAPTISTA J.L. et Coll. - Cytokine levels during mild and cerebral falciparum malaria in children living in a mesoendemic area. Trop. Med. Int. Health 1997 ; 2: 673-679.

10. SNOUNOU G. et Coll. - Non immune patients in the Democratic Republic of Sao Tomé e Principe reveal a high level of transmission of Plasmodium  ovale and Plasmodium  vivax despite low frequency in immune patients. Acta Trop. 1998 ; 70: 197-203.

11. KASSANKOGNO Y. - Aperçu sur le programme de lutte contre le paludisme africain pour la période 1996-1997. Malaria and Infectious Diseases in Africa 1999 ; n°9bis: 52-61