The Contribution of Human Mobility to Malaria Transmission in a Malaria Elimination Context in lusaka District

Abstract

Malaria is a major public health problem globally with an estimated 214 million cases and 438,000 deaths of which 90% occurred in sub Saharan Africa in 2015. Over 4 million cases were confirmed and 3000 deaths were reported in Zambia in 2013. Efforts to reduce the incidence of the disease are often undermined by a number of factors such as human mobility which may lead to introduction of imported infections. This study sought to determine the prevalence of imported cases in Lusaka district, identify risk groups, and investigate the association between mobility and malaria transmission by identifying factors associated with malaria importation. Using a cross sectional study, data was collected from 260 patients who presented with malaria and whose status was confirmed by rapid diagnostic test (RDT) or microscopy. Five health centers within Lusaka district were randomly sampled. Each confirmed malaria case was interviewed using a structured questionnaire to establish their demographic characteristics, travel history and preventive measures. Data was entered and analyzed using Stata software version 12. Of the 260 malaria positive cases investigated, 245 (94.23%) were classified as imported cases while 15 (5.77%) as local cases based on travel history. Age distribution ranged from 0 to 68 with a median age of 15 years (IQR 8 - 27). Imported cases came from all the provinces with Copperbelt province as the highest contributor (40.93%). Age group 0 to 14 was the most affected among the cases with a travel history (62.45%). A logistic regression analysis showed that factors associated with malaria importation by residence include use of prophylaxis AOR = 0.22 (95% CI: 0.60; 0.78), duration of stay AOR = 1.07 (95% CI: 1.03; 1.12) and frequency of travel AOR = 3.95 (95% CI: 1.35; 11.55). Mobility has influenced malaria transmission in Lusaka district by importing malaria leading to onward transmission and posing a challenge to malaria elimination and control. Taking of prophylaxis before travelling to a highly endemic region was protective. Residents who took anti-malarial drugs prior to travel were less likely to import. Children were more susceptible due to their weaker immunity. For every increase in the duration of stay in an endemic area there was an 8% chance of importing malaria.