PAE511 — Specific Infectious Diseases: Lecture Note

About this lecture note

This is the complete lecture note for PAE511 Specific Infectious Diseases. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.

Preview: opening of the note

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Course code: PAE 511 Course title: Specific Infectious Diseases Course credit load: 2 Units Series 1: Malaria in Children • Part 1.1: Introduction, Epidemiology, and Types of Malaria o Sub Part 1.1.1: Introduction to malaria o Sub Part 1.1.2: Species and types of malaria o Sub Part 1.1.3: Epidemiology of malaria in children • Part 1.2: Pathophysiology of Malaria o Sub Part 1.2.1: The malaria life cycle o Sub Part 1.2.2: Mechanisms of illness in uncomplicated malaria o Sub Part 1.2.3: Pathophysiology of severe malaria • Part 1.3: Clinical Features and Diagnosis of Malaria o Sub Part 1.3.1: Clinical features of uncomplicated malaria o Sub Part 1.3.2: Clinical features of severe malaria o Sub Part 1.3.3: Diagnosis and investigation of malaria • Part 1.4: Management, Prevention, and Control of Malaria o Sub Part 1.4.1: Management of uncomplicated malaria o Sub Part 1.4.2: Management of severe malaria o Sub Part 1.4.3: Prevention and control of malaria Introduction Picture a three year old brought to a rural clinic with three days of fever, chills, and vomiting, in a region where malaria transmission occurs year round. This presentation, one of the most common reasons a child is brought to a health facility across much of sub-Saharan Africa, opens the PAE 511 course, since malaria remains one of the leading causes of childhood illness and death in Nigeria and the wider region despite being both preventable and treatable when recognised promptly.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS The aim of this Series is to equip you with the knowledge required to understand the epidemiology and pathophysiology of malaria, recognise its clinical features, including the features of severe disease, and diagnose, manage, and prevent malaria in children. This Series begins with an introduction to the epidemiology and types of malaria, before turning to its pathophysiology. Next, we examine the clinical features and diagnosis of malaria, including severe malaria, before concluding with its management, prevention, and control. Series Learning Outcomes At the end of this Series, you should be able to: • SLO 1.1: describe the epidemiology of malaria in children, • SLO 1.2: list the species of malaria parasite and distinguish uncomplicated from severe malaria, • SLO 1.3: describe the pathophysiology of malaria, • SLO 1.4: describe the clinical features of uncomplicated malaria, • SLO 1.5: describe the clinical features and diagnostic criteria for severe malaria, • SLO 1.6: describe the diagnosis and investigation of malaria, • SLO 1.7: describe the management of uncomplicated and severe malaria, and • SLO 1.8: describe the prevention and control of malaria. 1.1 Introduction, Epidemiology, and Types of Malaria 1.1.1 introduction to malaria A single mosquito bite begins the whole process Malaria is a parasitic infection transmitted to humans through the bite of an infected female Anopheles mosquito, and remains one of the leading causes of childhood morbidity and mortality in sub-Saharan Africa, including Nigeria, where transmission is frequently year-round in many regions rather than confined to a specific season, meaning malaria must be actively considered in the differential diagnosis of almost any febrile child presenting from an endemic area. The disease is caused by parasites of the genus *Plasmodium*, with five species known to infect humans, and, while all can cause clinically significant illness, one species in particular is responsible for the overwhelming majority of severe disease and death, discussed further in the

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS next sub-Part, making accurate species identification, where possible, clinically relevant to anticipating disease severity and appropriate management. Fill in the blank: Malaria is transmitted to humans through the bite of an infected female ________ mosquito. 1.1.2 species and types of malaria The five species of *Plasmodium* that infect humans are Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi, with Plasmodium falciparum responsible for the great majority of severe disease and death in sub-Saharan Africa, reflecting both its predominance in the region and its distinct capacity to cause the severe complications discussed later in this Series. Clinically, malaria is broadly classified into uncomplicated malaria, in which the child is generally systemically well aside from fever and related symptoms, and severe malaria, in which one or more specific, serious clinical or laboratory features are present, a distinction of central importance since it directly determines the urgency and setting of required treatment, discussed in detail later in this Series. Fill in the blank: Plasmodium falciparum is responsible for the great majority of ________ disease and death in sub-Saharan Africa. 1.1.3 epidemiology of malaria in children Malaria disproportionately affects young children, particularly those under five years of age, who lack the partial immunity that develops gradually with repeated exposure in malaria-endemic regions, meaning this age group bears a substantial share of both malaria illness episodes and malaria-related deaths despite representing a smaller proportion of the overall population in affected areas. Transmission intensity varies considerably between regions and seasons, generally correlating with rainfall and temperature patterns that favour mosquito breeding, and children living in areas of high transmission intensity typically experience their most severe disease episodes earlier in life, before partial immunity has had the opportunity to develop, in contrast to children in lower transmission settings, who may experience severe disease at a somewhat older age. Fill in the blank: Malaria disproportionately affects children under ________ years of age.

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Figure 1.1: An Anopheles mosquito feeding, the vector responsible for malaria transmission. Pilot questions 1.1 1. Describe how malaria is transmitted to humans. (Linked to SLO 1.1) 2. List the five species of Plasmodium that infect humans. (Linked to SLO 1.2) 3. Name the species responsible for the majority of severe malaria in sub-Saharan Africa. (Linked to SLO 1.2) 4. Distinguish uncomplicated from severe malaria. (Linked to SLO 1.2) 5. Explain why children under five years bear a disproportionate burden of malaria. (Linked to SLO 1.3) 1.2 Pathophysiology of Malaria 1.2.1 the malaria life cycle Two hosts, two very different phases The malaria parasite has a complex life cycle involving both the human host and the Anopheles mosquito vector. Following an infected mosquito bite, sporozoites are injected into the bloodstream and travel to the liver, where they invade hepatocytes and undergo asexual

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS multiplication during the liver, or hepatic, stage, which is clinically silent, producing no symptoms during this initial phase of infection. After several days, the liver stage parasites rupture and release merozoites into the bloodstream, initiating the blood stage of infection, in which merozoites invade red blood cells, multiply, and cause the cells to rupture, releasing further merozoites to invade additional red cells in a repeating cycle, and it is this blood stage that is directly responsible for the clinical symptoms of malaria, discussed further in the next Part of this Series. Fill in the blank: Following an infected mosquito bite, sporozoites travel to the ________, where they undergo asexual multiplication. 1.2.2 mechanisms of illness in uncomplicated malaria The cyclical rupture of infected red blood cells releases parasite antigens and cellular debris into the circulation, triggering a host immune and inflammatory response, including release of pyrogenic cytokines, which is directly responsible for the characteristic fever, and often periodic fever pattern, together with the associated symptoms of headache, myalgia, and general malaise experienced by a child with uncomplicated malaria. The destruction of red blood cells during the blood stage also contributes to the development of anaemia, both through direct destruction of infected cells and, to a lesser extent, through increased splenic clearance of both infected and uninfected red cells, with the degree of anaemia generally related to the duration and intensity of infection. Fill in the blank: The cyclical rupture of infected red blood cells triggers release of ________ cytokines, causing fever. 1.2.3 pathophysiology of severe malaria Severe malaria, almost exclusively caused by Plasmodium falciparum, results from additional pathophysiological mechanisms beyond those seen in uncomplicated disease, most importantly cytoadherence, in which infected red blood cells develop surface changes that cause them to adhere to the walls of small blood vessels, particularly in the brain and other vital organs, a process that obstructs normal microvascular blood flow and contributes to the organ dysfunction characteristic of severe disease. This microvascular obstruction, combined with the inflammatory response and resulting metabolic derangement, including hypoglycaemia and lactic acidosis, underlies the specific severe manifestations of falciparum malaria, including cerebral malaria, in which

la-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS cytoadherence and inflammation within the cerebral microvasculature produce impaired consciousness and, often, seizures, discussed further in the next Part of this Series. Fill in the blank: Cytoadherence describes infected red blood cells adhering to the walls of small ________ vessels. Figure 1.2: A blood film showing red blood cells infected with malaria parasites. Pilot

This is the opening of the note. Read the full note or download the PDF to continue.