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Public Health Challenges with Sub-Saharan African Informal Settlements
Published in Igor Vojnovic, Amber L. Pearson, Gershim Asiki, Geoffrey DeVerteuil, Adriana Allen, Handbook of Global Urban Health, 2019
Yaoundé, the capital city of Cameroon, a country located in Central Africa, has an estimated population of 2.44 million inhabitants (Cameroon National Institute of Statistics 2011). Like many SSA cities of medium size, Yaoundé is experiencing a rapid urbanization process. The urbanization rate is currently estimated at 6.8% (Rotich et al. 2006) for Yaoundé against 3.3% for the whole country; 58% of the country is urbanized, and that percentage continues to grow annually (World Bank 2018). Our personal inquiries estimate that 49% of the city’s population is living in informal settlements (Ngom 2010). The city belongs to a holoendemic malaria zone, and shows an overlap of rural and urban settings.
Increased Number of Infections with Plasmodium Spp During a Period of Sociopolitical Instability
Published in Meera Chand, John Holton, Case Studies in Infection Control, 2018
Geraldine A O’Hara, Peter L Chiodini
Constant, year-round infection is termed stable transmission, generally occurring in areas with EIRs of ≥50 per year; in such areas, most malaria infections in adults are asymptomatic because frequent exposure throughout life enables development of protective immunity against disease although not against infection (Figure 17.1). Development of immunity to malaria is often referred to as premunition—the ability of the immune system to respond to parasites without eliminating the infection entirely. Premunition involves both B and T cells responding to frequent antigen exposure from infective bites. It is acquired relatively rapidly, is only partially effective, and is short-lived. However, it is highly effective at preventing severe disease and occurs in hyper- and holoendemic areas. In areas where transmission is low, highly seasonal, or focal, immunity is not acquired or only partially acquired, and symptomatic disease occurs at all ages; this is termed unstable transmission. Malaria behaves like an epidemic disease in areas with unstable transmission. Even in areas with stable transmission, epidemics may develop; climactic instability such as heavy rains following a period of drought, migration of refugees from a nonmalarious region to an area of high transmission, and disruption in malaria control and treatment will alter the epidemiological picture.
The epidemiology of malaria
Published in David A Warrell, Herbert M Gilles, Essential Malariology, 2017
Robert W Snow, Herbert M Gilles
During the 1950s, the WHO derived a classification of endemicity based upon the spleen rate (another proxy marker of malaria endemicity). This classification was later revised by Metselaar and Van Thiel in relation to the parasite rate. These definitions of hypoendemic, mesoendemic, hyperendemic and holoendemic malaria are described in Table 5.2. The cut-offs of either spleen or parasite rates are arbitrary and do not capture the seasonal nature in transmission, and thus the annual changes in spleen or parasite rates. More importantly, they do not distinguish between areas that may experience 20 new infections per person per annum compared to those where over 200 new infections are received by the population each year, both potentially classified as holoendemic on the basis of a cross-sectional parasitological survey. Some common terms used in malaria epidemiology are given in Table 5.3.
Overcoming challenges in the diagnosis and treatment of parasitic infectious diseases in migrants
Published in Expert Review of Anti-infective Therapy, 2020
Francesca F. Norman, Belen Comeche, Sandra Chamorro, Rogelio López-Vélez
The clinical manifestations of malaria depend on the acquired immunity that the individual has developed during life. Across sub-Saharan Africa where the disease is holoendemic, most people are frequently infected by P. falciparum, and the majority of infected adults rarely experience overt disease. This Natural acquired immunity (NAI) is compromised in pregnant women, especially primigravidae, and adults leaving endemic areas appear to lose NAI, at least temporarily [17]. Recently arrived migrants thus often have milder symptoms and lower parasite loads due to their semi-immunity [18]. Submicroscopic malaria (SMM), defined as low-density Plasmodium infection detected only by molecular methods, only occasionally causes acute disease but can infect mosquitoes and contribute to transmission [19]. A possible association between concomitant filarial infection and presenting submicroscopic malaria has been described and also in association with hemoglobinopathies [19]. Helminthoses, such as filariasis, might exert some protective effect against malaria, leading to lower parasitic loads, which might translate into clinical protection against severe malaria [20].
Global variation in diurnal cortisol rhythms: evidence from Garisakang forager-horticulturalists of lowland Papua New Guinea
Published in Stress, 2018
Samuel S. Urlacher, Melissa A. Liebert, Martina Konečná
Detailed background information for the Garisakang is provided elsewhere (Konečná & Urlacher, 2017). Briefly, the Garisakang are a subsistence-based indigenous group of ≍ 500 individuals inhabiting the remote Middle Ramu River Valley of Madang Province, PNG. Similar to many other Oceanic populations (Sahlins, 1963), Garisakang social structure is patrilineal with mixed-polygyny and established big men exercising dominant political influence. Since 1995, a large portion of the Garisakang has resided in a single community – Wanang – with a current population of ≍ 200 individuals. The Wanang region is characterized by dense evergreen tropical forest, mean daytime temperature of 26 °C, and heavy rainfall totaling ≍ 3500 mm annually (Anderson‐Teixeira et al., 2015). Government infrastructure and access to markets or modern healthcare is limited; Wanang possesses no electricity, running water, clinic, or reliable road access. To obtain basic services, community members must walk or attempt to hitchhike on a seasonal dirt logging road to Madang town located ≍ 80 km away. This combination of isolation and tropical conditions results in high rates of infectious and parasitic disease, including holoendemic malaria, as is typical of lowland PNG (Müller, Bockarie, Alpers, & Smith, 2003; Shaw, 1984). The Garisakang remain reliant on slash-and-burn horticulture, foraging, bow hunting, and fishing to supply their diet. Consumption of market foods to supplement overall nutritional constraint is uncommon, with residents in 2015 reporting eating, on average, fewer than two market items (e.g. rice, noodles, biscuits) per month. Engagement in a mixed forager-horticulturalist lifestyle fosters high levels of habitual physical activity, particularly among women who are responsible for the bulk of household domestic and gardening activities.