TABLE 10-1 Burden of Infectious and Parasitic Disease in Males and Females, Worldwide and in Sub-Saharan Africa, by Cause, 1990 (in hundreds of thousands of DALYs lost)

 

Sub-Saharan Africa

Worldwide

Disease

 

M

F

M

F

Malaria

''Tropical cluster"a

Schistosomiasis

Trypanosomiasis

Onchocerciasis

Trachoma

Leishmaniasis

Leprosy

Lymphatic filariasis

161.0

39.0

23.1

9.0

3.7

2.1

1.9

1.2

1.3

154.

25.8

11.8

8.8

2.7

6.9

2.0

1.1

0.5

182.3

75.0

29.9

9.0

3.7

9.3

12.0

5.1

5.6

175.0

51.0

15.4

8.8

2.7

23.7

8.6

5.1

2.9

a Defined as including: trypanosomiasis, Chagas' disease, schistosomiasis, leishmaniasis, lymphatic filariasis, and onchocerciasis (Murray and Lopez, 1994). Malaria, leprosy, and trachoma are addressed separately in the Global Burden of Disease categorization.

SOURCE: Murray and Lope, 1994.

African trypanosomiasis, onchocerciasis, and leishmaniasis. Even when episodes of these diseases do not proceed to mortality, they tend to generate considerable morbidity. This is also true for the other four, nonlethal, diseases addressed in this chapter. Thus, it is morbidity, or disability, that has the greatest weight in the total burden of these diseases as a group. Tables 10-3 and 10-4 desegregate that burden, first in mortality, and second in disability (morbidity).

Finally, Table 10-5 summarizes the gender burden of the tropical infectious diseases in the same fashion as other topics have been presented in each of the chapters of this report: that is, subcategorized by the degree to which the burden of each disease is distinctive for females. Contemplated as a group, the tables indicate that, with little exception, males in Sub-Saharan Africa have higher overall burdens of tropical disease, with higher rates of both mortality and disability, than females experience in the region, although there is significant internal variation.

This general conclusion coincides with several perspectives in the literature that have become almost standard. The first is that the overall worldwide burden of premature mortality and morbidity is higher in males than it is in females, and male life expectancy is correspondingly lower.

The second perspective is that the only noteworthy distinctions between males and females in disease susceptibility and expression lie in their relationship with female reproductive function. One consequence of this viewpoint is that biomedical research on sex differences in infectious disease has focused mainly on that relationship, with emphasis on pregnancy and pregnancy outcomes, placental transmission, and maternally induced protection. Because of these emphases, research into the longitudinal impact of infectious diseases across the female life span, as well as the simultaneous and progressive interactions of those diseases with other maladies and conditions, has been deficient (Feldmeier and Krantz, 1992; Feldmeier et al., 1992; Vlassoff and Bonita, 1994). Table 10-6, which present a detailed analysis of the sequelae of the tropical infectious diseases across the female life span, makes it abundantly clear that such a narrow focus does not fit the facts.

The third perspective is that, with the exception of the role of the reproductive factor, any other differences in male/female mortality and disability rates are caused by variations in the nature and degree of exposure and in the social, economic, cultural, and personal factors that influence both exposure and the impact of a given disease (Brain and Brain, 1992; Bunny and Medley, 1992).

The present state of the scientific literature offers little justification for disagreeing with any of these perspectives, nor has it offered much basis for expecting either sex to be genetically more predisposed to communicable disease infection. Nevertheless, there is reason begin questioning this assumption. Analysis of the influence of



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