Malaria Control in South America--Response to P.C. Matteson.

To the Editor: Dr. Matteson, whose letter relies heavily on unpublished information and nonrefereed publications, states that growing drug resistance has contributed to increasing malaria. While drug resistance is important, when DDT use declined below effective levels (1), the proportion of Plasmodium falciparum infections (including infections with resistant strains) compared with P. vivax infections (no resistance) did not progressively increase (12). Moreover, malaria has increased in Central America, where drug resistance is unknown (3-6). As for attributing increasing malaria to deteriorating public health systems, the changes imposed on developing countries (in organizational structures of malaria control programs and prohibiting DDT [1, 7]) correlate with increasing malaria rates (1).

Dr. Matteson states that large-scale migration explains why almost all Brazilian malaria cases occur in the Amazon Basin. However, DDT cleared malaria from the more populated and temperate southern, regions of the country (8, unpublished report: U.S. Agency for International Development review in 1973-74 of Brazil's malaria eradication program). When DDT was in full use (pre-1980), large increases in malaria did not accompany population movement (1). With the 1970s' colonization program of the Basin came malaria problems, but not large population-based malaria increases. DDT prevented that (1,9-11). However, since DDT has been eliminated, persistent urban malaria is again becoming a problem (12-16).

Other factors (biting behavior, housing conditions, and human behavior), which Dr. Matteson attributes to increasing malaria, have always thwarted interdiction of malaria transmission in the Amazon Basin (17; 18; an unpublished report: U.S. Agency for International Development review in 1973-74 of the malaria eradication program in Brazil) and are no more important today than they were before.

A UN-facilitated global negotiation process cited as a meaningful debate for malaria control is an effort to provide a legally binding agreement for global elimination of DDT and other persistent organic pollutants, not an open forum for debate of DDT use for malaria control.

Dr. Matteson claims that DDT is associated with reduced lactation. In the United States, where DDT has been banned for 26 years, mothers who stay home breast-feed for an average of 25.1 weeks--mothers who work parttime, for 22.5 weeks (19). In Belize, mothers in urban areas, where DDT is not used for malaria control, breast-feed less than 38.4 weeks--mothers in rural areas with lifetime exposures to DDT breast-feed more than 57.2 weeks (20).

The World Wildlife Fund's mass balance model of DDT sprayed in houses used to refute our assessment that DDT does not readily move away from sprayed houses also mentions that "There are few ... data against which to validate the results of this ... model, although actual data ... should not be difficult to obtain." (21). Studies of DDT use in agriculture show that most DDT settles where it is applied (22).

Studies have shown no meaningful population-based adverse health effects from DDT use, despite more than 50 years' exposure, and evidence argues forcefully that DDT does not cause breast cancer (23).

References

(1.) Roberts DR, Laughlin LL, Hsheih P, Legters LJ. DDT, global strategies, and a malaria control crisis in South America. Emerg Infect Dis 1997;3:295-302.

(2.) Brasil. Registro de casos de malaria--960 a 1997. Gerencia Tecnica de Malaria/FNS-Brasilia, Brasilia, Brasil.

(3.) Pan American Health Organization. Status of malaria programs in the Americas. XL report. Washington: The Organization; 1991. p. 145.

(4.) Pan American Health Organization. Status of malaria programs in the Americas. XLII report. Washington: The Organization; 1994. p. 116.

(5.) Pan American Health Organization. Status of malaria programs in the Americas. XLIII report. Washington: The Organization; 1995. p. 25.

(6.) Pan American Health Organization. Status of malaria programs in the Americas. XLIV report. Washington: The Organization; 1996. p. 23.

(7.) Roberts DR. Resurgent malaria: DDT and global control. Medicine 1998;34:36-8.

(8.) de Bustamante FM. Distribuicao geografica e periodicidade estacional da malaria no Brasil e sua relacao com os fatores climaticos. Situacao atual do problema. Revista Brasileira de Malariologia e Doencas Tropicais 1957;9:181-90.

(9.) Pinheiro FP, Bensabath G, Rosa APAT, Lainson R, Shaw JJ, Ward R, et al. Public health hazards among workers along the Trans-Amazon Highway. Journal of Occupational Medicine 1977;19:490-6.

(10.) Smith NJH. Colonization lessons from a tropical forest. Science 1982; 13:755.

(11.) Roberts DR. Health problems of colonists. Science 1982;217:484.

(12.) Sandoval JJF, Diniz R, Saraiva MGG, da Silva EB, Alecrim WD, Alecrim MGC, et al. Historico da malaria na cidade de Manaus e proposta de controle integrado. Rev Soc Bras Med Trop 1998;31, Suplemento 1:141.

(13.) Amaral JCOF, Machado RLD, Segura MNO, Oliveira GS, Povoa MM. Avaliacao longitudinal da infeccao causada por Plasmodium falciparum e/ou Plasmodium vivax na populacao de duas localidades de Icoaraci, Distrito de Belem, Para. Rev Soc Bras Med Trop 1998;31 Suplemento 1:16.

(14.) da Silva EB, Costa MF, Melo YFC, Alecrim MGC. Inquerito soroepidemiologico numa area urbana em fase de ocupacao, na cidade de Novo Aryao-Amazonas-Brasil. Rev Soc Bras Med Trop 1998;31 Suplemento 1:82.

(15.) Ventura AM, Pinto AY, Uchoa R, Calvosa V, Santos MA, Filho MS, et al. Malaria por Plasmodium vivax em criancas-I-aspectos epidemiologicos e clinicos. Rev Soc Bras Med Trop 1998;31 Suplemento 1:82.

(16.) Suarez MC, Fe NF, Alecrim WD. Estudo do processo de transmissao da malaria em uma area de invasao recente na cidade de Manaus Amazonas. Estudo entomologico. Rev Soc Bras Med Trop 1998;31 Suplemento 1:15-6.

(17.) Forattini OP. Entomologia medica: I volume parte Geral, Diptera, Anophelini. Sao Paulo (Brasil): Faculdade de Higiene e Saude Publica; 1962. p. 414.

(18.) Rachou RG. Some manifestations on behaviouristic resistance in Brazil. Semina Suscep. Insects to insecticides, Panama, Report.: WHO 1958:208-95.

(19.) Frank E. Breastfeeding and maternal employment: two rights don't make a wrong. Lancet 1998;352:1083-4.

(20.) Central Statistical Office, Belize. 1991 Belize family health survey, final report. Reprinted by U.S. Dept of Health and Human Services; 1992. p. 69.

(21.) Resolving the DDT dilemma: protecting biodiversity and human health. Toronto, Canada: World Wildlife Fund-Canada; 1998.

(22.) World Health Organization. DDT and its derivatives. Environmental health criteria 9. Geneva: The Organization; 1979. p. 194.

(23.) Safe, SH. Xenoestrogens and breast cancer. N Engl J Med 1997;337:1303-4.

Donald R. Roberts and Larry L. Laughlin The Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA