Age-dependent sex bias in clinical malarial disease in hypoendemic regions

• Published in: PloS one 2012-04, Vol.7 (4), p.e35592-e35592
• Main Authors: Pathak, Sulabha, Rege, Mayuri, Gogtay, Nithya J, Aigal, Umesh, Sharma, Surya Kant, Valecha, Neena, Bhanot, Gyan, Kshirsagar, Nilima A, Sharma, Shobhona
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Age Factors; Anemia; Animal models; Animals; Anopheles - physiology; Aquatic insects; Behavior, Animal - physiology; Bias; Biology; Child; Child, Preschool; Children; Datasets; Disease Vectors; Endemic Diseases; Exposure; Female; Females; Gender; Health care access; Hormones; Hospitals; Humans; India - epidemiology; Infections; Infectious diseases; Malaria; Malaria, Falciparum - epidemiology; Malaria, Falciparum - parasitology; Malaria, Vivax - epidemiology; Malaria, Vivax - parasitology; Male; Males; Medicine; Middle Aged; Mosquitoes; Parasites; Phylogeography; Plasmodium falciparum; Plasmodium falciparum - physiology; Plasmodium vivax - physiology; Population Surveillance; Puberty; Retrospective Studies; Sex; Sex discrimination; Sex Factors; Sex hormones; Sexism; Sexual dimorphism; Statistical analysis; Statistical tests; Studies; Surveillance; Trends; Tropical diseases; Vector-borne diseases; Worms
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0035592

Experimental models show a male bias in murine malaria; however, extant literature on biases in human clinical malaria is inconclusive. Studies in hyperendemic areas document an absence of sexual dimorphism in clinical malaria. Data on sex bias in clinical malaria in hypoendemic areas is ambiguous--some reports note a male bias but do not investigate the role of differential mosquito exposure in that bias. Moreover, these studies do not examine whether the bias is age related. This study investigates whether clinical malaria in hypoendemic regions exhibits a sex bias and whether this bias is age-dependent. We also consider the role of vector exposure in this bias. Retrospective passive clinical malaria datasets (2002-2007) and active surveillance datasets (2000-2009) were captured for the hypoendemic Mumbai region in Western India. To validate findings, passive retrospective data was captured from a primary malaria clinic (2006-2007) in hypoendemic Rourkela (Eastern India). Data was normalized by determining percent slide-positivity rates (SPRs) for males and females, and parasite-positivity distributions were established across age groups. The Mann-Whitney test, Wilcoxon Signed Rank test, and Chi-square analysis were used to determine statistical significances. In both the Mumbai and Rourkela regions, clinical malaria exhibited an adult male bias (p