
Vol. 17, No. 4	December 1996

MALARIA IN THE AMERICAS

In 1995 the population of the Region of the Americas was estimated at 774 million, of which 248 million (32.0%) lived in areas where ecological conditions were propitious for the transmission of malaria.

In order to obtain a more accurate picture of the distribution of the disease, the countries of the Americas have redefined their malarious areas on the basis of different levels of risk of exposure to transmission (low, medium and high). Approximately 36 millon people live in the medium risk areas and around 42 millon in high risk areas. Exposure risk is the result of factors related to population movement, social stability, and adoption of individual attitudes and behaviors which facilitates contact between humans and vectors. These attitudes and behaviors are further influenced by limited access to appropriate diagnosis and treatment.

In 1995, 1,30 million cases of malaria have been reported, an increase of 14,6% in relation to 1994 when 1,11 millon cases occurred. (See Epidemiological Bulletin, Vol. 16, No. 3, September 1995). The increase in the number of cases could be partially due to the steady increase in infections caused by P. falciparum, especially in Bolivia, Colombia and Perú.

The malaria morbidity rates increased on the basis of the total population of the Americas, from 145.9 per 100,000 in 1994 to 168.16 per 100,000 in 1995. Morbidity rates for the population inhabiting areas ecologically propitious for transmission increased from 481.6 to 523.26 per 100,000 in the same period.

Brazil reported the greatest absolute number of malaria cases in the region, 565,727 cases (44.2%), followed by the Andean Area with 461,121 cases (35.9%). However, the greatest risk of transmission is seen in the subregion which includes Guyana, French Guiana, and Suriname with an Annual Parasite Index (API) of 228.0/1,000, followed by Belize, API of 44.6/1,000 and Brazil with 29.8/1,000. The greatest increases of transmission intensity during 1995 were reported by Belize, Bolivia, Colombia, Peru and Nicaragua.

Table 1 presents the distribution of cases, the respective API and the parasites found in 21 countries with active malaria control program in the Region.

The coverage of epidemiological surveillance activities continues to increase in areas of high and medium risk, 14% and 8% respectively in relation to 1994. This comes together with a steady supply of blood smears in areas of low and no risk.

TABLE 1 Epidemiological Status of 21 Countries with Malaria Programs, 1995

		Blood Slides			Parasite Species
Countries by Geographic Subregion	Population Malarious Areas *	Examined	Positive	API	falciparum & mixed	vivax	malariae
Mexico	47,505	1,977,691	7,316	0.15	73	7,243	0
Belize	211	37,266	9,413	44.61	475	8,938	-
Costa Rica	1,103	143,407	4,515	4.09	16	4,499	-
El Salvador	5,400	169,267	3,362	0.62	6	3,362	-
Guatemala	4,202	135,095	24,178	5.75	671	23,490	17
Honduras	4,740	324,234	59,446	12.54	1,124	58,322	-
Nicaragua	4,147	493,399	69,444	16.75	4,103	65,322	-
Panama	2,165	222,498	730	0.34	18	712	-
Sub-total	21,968	1,525,166	171,088	7.79	6,413	164,645	17
Haiti**	5,500	54,973	23,140	4.21	23,140	-	-
Dominican Rep.	7,505	380,143	1,808	0.24	1,807	1	0
Sub-total	13,005	435,116	24,948	1.92	24,947	1	0
French Guiana	49	52,521	4,711	96.14	4,137	545	29
Guyana	132	296,370	59,311	449.33	29,652	29,335	-
Suriname	42	38,613	6,606	157.29	6,270	256	80
Sub-total	223	259,261	50,883	228.17	32,910	17,786	109
Brazil	19,010	2,582,017	565,727	29.76	203,402	361,560	765
Bolivia	3,122	152,748	46,911	15.03	3,374	43,537	-
Colombia	24,655	667,473	187,082	7.59	62,687	124,354	41
Ecuador	6,205	253,714	18,128	2.92	4,738	13,390	-
Peru	18,507	833,614	192,629	10.41	37,591	152,868	62
Venezuela	17,419	166,533	16,371	0.94	2,678	13,672	21
Sub-total	69,908	2,074,082	461,121	6.60	111,068	347,821	124
Argentina	5,610	12,986	1,065	0.19	-	1,065	-
Paraguay	1,382	86,664	898	0.65	35	862	1
Sub-total	6,992	99,650	1,963	0.28	35	1,927	1
T O T A L	178,611	9,076,226	1,302,791		385,997	913,333	1,016

* Population by thousands
** No 1995 data available, 1994 data used

In recent years the epidemiological stratification of malaria in the Americas has been accompanied by the integration of case finding, diagnosis, and immediate treatment into the local health services. In 1995, 19 of 21 countries that had been reported cases, 8,3 million laboratory tests have been performed in persons with suspected cases of malaria. The diagnostic efficiency of the local health services was 16.9%, in 3,299,216 tests performed whereas active surveillance continues to show a low diagnostic efficiency and high operational cost, confirming only 2.42% of "recent fever" cases, in 1,974,625 examinations.

In recent years the epidemiological redefinition of areas of risk has lead to the concentration of efforts in high priority areas and the improvement in the availability of treatment per diagnosed case. In the Americas until 1990 only 40 complete treatments were available for every 1,000 people exposed to the risk of contracting malaria. The introduction of epidemiological stratification in the national control programs as well as the further implementation of the "Global Malaria Control Strategy," which calls for an emphasis on clinical management of the disease have progressively improved the availability of treatment which is now 61,5 per 1,000 people.

Vector control activities continue to be applied by the countries as a means to prevent transmission. A clear shift away from the organochlorine and organophosphorus products, such as DDT, towards greater use of the synthetic pyrethroids such as malathion and fenithrotion has been observed.

Table 2 presents the geopolitical location and demographics of high risk areas, the causes of exposure, and the measures used for control. From the characterization of the factors that lead to persistence of transmission, various control measures can be identified. There is still a need for intersectoral coordination in order to ensure the sustainability of these measures.

TABLE 2 Malarious Areas at High Risk of Transmission, and Control Priorities, 1995

Countries	Population	km2	Reported Cases	Control Measures Applied in Different Areas	Main Vectors
MEXICO: Campeche Chiapas Guerrero Michoacan Oaxaca Quintana Roo Sinaloa Tabasco	645,608 3,288,845 2,950,337 2,799,278 3,043,770 923,653 2,381,142 1,709,246	51,833 72,002 62,718 57,309 87,922 50,350 58,092 24,661	62 2,351 193 567 1,137 245 1,284 130	House, larvacide and aerial spraying; individual and mass radical treatments; entomological studies; and promotion of environmental management.	A. albimanus A. vestitipennis A. pseudopunct
Sub-total	17,741,879	464,887	5,969
BELIZE: Corozal Orange Walk Belize Cayo Stann Creek Toledo	30,809 33,207 61,733 40,800 19,575 18,877	1,390 1,256 701 3,585 1,289 2,190	673 621 503 3,742 1,701 2,174	Spraying and drug therapy.	A. albimanus
Sub-total	205,001	10,411	9,414
COSTA RICA: Canton Los Chiles Canton Limon Canton Talamanca Canton Matina	20,794 76,032 27,047 23,324	1,358 1,766 2,810 773	401 1160 424 795	Radical treatment, focal spraying and aerial spraying.	A. albimanus
Sub-total	147,197	6,707	2,780
EL SALVADOR: Costa Pacifico area hiperendem.	1,233,133	4,754	2,782	Spraying, drug therapy, larvicides, structural works, mosquito bednets.	A. albimanus
GUATEMALA: El Peten Huehuetenango Alta Verapaz Escuintla Ixcan Izabul San Marcos	310,008 816,376 379,318 428,073 36,958 370,859 122,851	351,854 ... 5,992 4,102 ... 7,491 702	7,708 1,923 3,612 2,674 4,682 710 1,720	Non-coordinated house spraying; low diagnositic and treatment coverage.	A. albimanus
Sub-total	2,464,443	370,141	23,029
HONDURAS: Health Region II Health Region III Health Region VI Health Region VII Health Region VIII	565,209 1,504,379 604,354 356,810 43,582	... ... ... ... ...	9,370 9,330 15,290 14,065 3,214	Integrated measures implemented; drug treatment; different spraying methods for physical and larval control; and community participation.	A. albimanus A. darlingi
Sub-total	3,074,334	...	51,269
NICARAGUA: Chinandega Leon Jinotega Matagalpa Nueva Segovia R.A.A.N. Granada Managua Chontales	348,971 330,070 214,070 364,790 151,324 175,405 153,183 1,056,702 296,561	4,926 5,107 9,755 8,523 3,123 32,159 929 3,672 6,378	8,000 14,611 4,708 8,537 2,496 2,749 2,159 16,812 3,014	...	A. albimanus A. pseudopunct.
Sub-total	3,091,076	74,572	63,086
PANAMA: Bocas del Toro Changuinola Chiriqui Grande Chepigana Donoso Renacimiento San Blas Tole	22,622 67,517 14,400 30,280 11,525 10,382 37,011 30,021	2,123 2,281 2,628 7,700 1,048 2,878 2,823 3,203	213 133 69 47 32 41 62 32	...	...
Sub-total	223,758	24,684	629
HAITI:	...	...	...	...	...
DOMINICAN REPUBLIC: Pepillo Salcedo	8,735	...	116	Prophylactic treatment of immigrants, medicinal barriers, spraying in house and surrounding areas, cleanup of canals, fish farming, Bti treatment of breeding sites.	A. albimanus
Sub-total	8,735	...	116
FRENCH GUIANA: Camopi/T-Sauts Bas Oyapock Moroni	746 1,605 6,793	1,003 340 2,512	91 161 3,996	API= 464.6/1.000 AFI= 452.1/1.000	A. darlingi
Sub-total	9,144	3,855	4,248
GUYANA:	132	...	59,311	API= 449.3/1.000 AFI= 224.6/1.000	A. darlingi
BRAZIL: Acre Amapa Amazonas Maranhao Mato Grosso Para Rondonia Roraima Tocantins	484,400 324,841 889,549 863,580 615,693 2,022,048 874,870 262,201 62,018	... ... ... ... ... ... ... ... ...	35,732 17,028 40,732 26,320 57,126 176,118 132,236 39,574 1,792	API = 82.3/1.000 AFI = 29.6/1.000	A. darlingi
Sub-total	6,399,200		526,658
BOLIVIA: Depart.:BENI Rebiralta Guayaramerin Depart.:PANDO Provincias Puerto Rico/Conquista Depart.: SANTA CRUZ Andrez Ibanez Depart.: TARIJA Yaccuben, Benneijo Entre Rios, Villamen Dept.:CHUQUISACA Monteagudo/Huacoreta	45,000 24,000 4,400 300,000 151,000 76,000	34,000 22,000 18,000 86,000 38,000 24,900	1,725 870 1,421 6,300 11,549 5,250	Supervised case findingand treatment, chemical control, physical control of breeding sites through petroleumapplications. Health education on prevention and control.	A. darlingi A. pseudopunct.
Sub-total	600,400	222,900	27,115
COLOMBIA: 1. Bajo Cauca-Uraba 2. Orinoquia 3. Pacifico 4. Amazonia	971,686 578,234 959,419 490,758	55,000 90,063 80,000 110,000	106,773 37,158 22,001 12,594	House spraying, physical control. Impregnated bednets, topical repellents. API = 59.5/1.000 AFI = 20.5/1.000	A. albimanus A.nuneztovari A. darlingi A. puntimacula
Sub-total	3,000,097	335,063	178,526
ECUADOR: Esmeralda El Oro Los Rios Manabi Canar Cotopaxi Loja Sucumbios Pastaza Guayas Napo	394,485 425,503 564,372 1,093,830 37,047 37,924 195,281 81,275 14,208 2,702,074 112,860	14,597 302 1,992 4,015 349 233 610 2,049 24,160 ... 542	6,079 1,099 2,068 2,536 793 230 368 739 228 2,145 512	House spraying. API = 3.0/1.000 AFI = 0.5/1.000	A. albimanus
Sub-total	5,658,859	48,849	16,797
PERU: Piura L. Castillo Tumbes Loreto Jaen-Bagua Junin San Martin Ucayali Madre de Dios Pasco	823,315 672,291 164,730 701,513 501,359 1,176,478 574,450 321,819 66,684 238,807	24,858 15,238 4,657 368,851 40,563 44,409 51,253 102,410 53,385 8,745	12,301 25,508 1,899 37,871 18,858 38,941 15,514 5,331 2,026 3,951	Diagnosis and treatment through general health services. Very limited residual spraying, aerial spray, environmental sanitation. API = 30.9/1000 AFI = 10.2/1000 only for the population of Piura, L. Castillo, Tumbes, Jaen and San Martin.	A. pseudopunct. A.benarrochi
Sub-total	5,241,446	714,369	162,200
VENEZUELA: Amazonas Bolivar Sucre Tachira Apure (S.C.) Delta Amacuro	64,512 151,452 46,454 17,601 17,988 32,311		1,941 7,286 2,475 410 918 591	Spraying and fogging, use of larvicides. API = 41.2/1000 AFI = 7.2/1000	A. darlingi A. aquasalis A.nuneztovari
Sub-total	330,318		13,621
ARGENTINA: Fase De Ataque	24,741	11,275	858	Epidemiological surveillance and spraying.	A. pseudopunc.
PARAGUAY Caaguazu Alto Parana Aambay Canindeyu	418,136 439,964 108,058 112,306	11,474 14,895 12,933 14,667	592 142 36 99	Case detection and treatment, house spraying.	A. darlingi
Sub-total	1,078,464	53,969	869

... Information not available

By and large, the control programs are undergoing a drastic reduction in budgetary funding and, therefore, each year are obtaining more of their financing through external loans and grants from outside the health sector budget. Table 3 indicates further reductions in the regular budgets as compared to 1994, both in the total amount of money and in relation to the population exposed to medium and high risk.

TABLE 3 National Budget and Non-Budgetary Contribution to Malaria Control Programs in the Americas 1992-1995 (in U.S. Dollars)

	National Malaria Budget	Contributed Funds, Loans Other	National Malaria Budged	Contributed Funds, Loans Other	National Malaria Budget	Contributed Funds, Loans Other
Countries	1993		1994		1995
Argentina Bolivia Brazil Colombia Costa Rica Cuba Dominican Republic Ecuador El Salvador Guatemala Haiti Honduras Mexico Nicaragua Panama Paraguay Peru Venezuela	1,826,000 187,066 97,124,000 13,542,381 1,714,017 ... 599,334 4,963,244 1,220,930 2,434,719 20,00 2,016,013 28,441,613 ... 3,719,976 6,405,522 ... 6,976,914	- - 5,500,000 - 344,310 ... 517,815 - 1,023,255 166,985 250,000 283,072 - 301,647 71,000 - - 4,600,000	3,000,000 619,430 12,117,647 14,614,045 138,000 ... 667,171 5,253,888 1,314,286 ... 50,000 1,611,927 30,297,000 ... 3,633,545 1,030,831 3,062,696 24,233,445	- 20,000 24,400,000 - 393,308 ... ... - 682,571 288,703 ... 576,382 - 386,004 124,224 - - 25,319,792	510,900 871,749 35,294,157 2,518,694 1,527,035 ... 758,525 6,057,590 1,321,838 ... ... 956,146 16,944,000 ... 3,742,203 1,362,444 2,865,431 ...	- ... 35,633,326 - 1,065,088 ... 113,717 - 402,299 41,000 ... 40,000 - 250,000 145,683 - - ...
Sub-total	171,191,729	13,058,084	101,643,911	52,190,984	74,730,712	37,691,113
Guyana Belice Dominica French Guiana Granada Guadeloupe Island Jamaica Panamá (C.Z.) Saint Lucia Suriname Trinidad and Tobago	538,535 477,919 ... 91,973 ... ... ... ... ... ... ...	- 100,000 ... - ... ... ... ... ... ... ...	295,483 617,462 ... ... ... ... ... ... ... 5,494 ...	- 79,407 ... - ... ... ... ... ... ... ...	... - ... - ... ... ... ... ... 49,000 ...	... 760,819 ... 328,048 ... ... ... ... ... 758,525 ...
Sub-total	1,108,427	100,000	918,439	1,847,392	49,000	1,847,392
Total	172,300,156	13,158,084	102,562,350	54,083,376	74,779,712	39,538,505
Grand Total	185,458,240		156,600,726		114,318,217
Funds/person in malarious area	$0.64		$0.68		$0.47

Note: Funds/person only from reported data.

The complete report of the Malaria Situation in the Americas, 1995, is available in english and spanish. Requests of it should be made to: Communicable Diseases Program, Division of Diseases Prevention and Control; Pan American Health Organization, 525 23rd Street, N.W., Washington DC, 20037-2895, USA;
Fax: (202) 862-8483.

Source: Communicable Disease Program, Division of Disease Prevention and Control (HCP/HCT), PAHO/WHO.

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MALARIA IN THE AMERICAS