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Epidemiological Bulletin
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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