Welcome to this presentation on ticks and mites. My name is Mramba Nyindo, I prepared this presentation with the we're at the Kilimanjaro Christian Medical University College in Moshi, Tanzania. Ticks and mites are described as ectoparasites. Ticks transmit Lyme disease and that is one of their importance. Lyme disease is found in Europe, Asia and the USA. What about mites? They cause scabies. This is an important disease in sub-Saharan Africa, scabies. What are ticks and what are mites, one might ask? Arcarology is the science that is concerned with the ticks and mites. The term acaricides, which are chemicals which kill ticks is derived from acarology. Note that ticks, they are not insects. But the ticks are typical arachnids. There are two families of ticks, hard and soft ticks. They are related to scorpions, spiders, and mites. The main features of ticks, they have eight legs, the body is unsegmented and the anterior part has a structure termed gnathosome or capitulum. There is scutum which is hard chitinous covering on the dorsal surface of ticks. In the female hard tick, the scutum covers only about one third of the dorsal surface area. Ticks feed on blood. A tick lacerates host skin epidermis, it will secrete saliva and it will insert its mouth parts at the site it has lacerated. It will spit saliva. Tick saliva is both cytolytic and anticoagulant. The anticoagulant provides an uninterrupted flow of blood for the tick to imbibe. The tick will burrow its mouth parts further into the skin, and it will secrete cement material and this is used to anchor the tick onto the host. It is anchored there. It is very, very difficult to pull a tick out of the skin where it has penetrated. It is cemented there. These are three types of ticks, actually forms of ticks. This is the female with a scutum, about one third layer. This is the male, where the scutum covers the entire body, and this is the larva or nymph stage. These are eight-legged organisms, hard ticks, Ixodid species, diagrammatical error presented. This is a tick which has not fed. This is a tick that has imbibed to capacity, engorged to capacity, this is as big as they can get. Tick bites can also cause paralysis. This paralysis is due to neuro-toxin, which leads to weakness of lower limbs, incoordination, falling down, muscle weakness, dysphagia and respiratory failure and death. Ioxdes ticks will transmit Lyme disease, which is caused by Borrelia burgdorferi. Borrelia burgdorferi is transmitted to humans by the hard ixodid ticks. Lyme disease takes different disease manifestations, as will be described on the clinical manifestation of Lyme disease. What about soft ticks? They transmits borreliosis. Borrelia, what are they? They are gram-negative, irregularly coiled helical spirochetes. Borrelia duttoni causes endemic relapsing fever and is transmitted by the soft tick Ornithorodorus moubata. Very common in Tanzania, for that matter. You should note that lice transmit Borrelia recurrentice. This is Orinthodorus moubata ventral surface, the legs are visible there. This is the dorsal side, there is no scutum on this as it happens with hard ticks. Borrelia duttoni is represented here in human blood film from a Tanzania patient. Spirochete and these are blood cells. As I said, this causes endemic relapsing fever which is a cosmopolitan disease caused by Borrelia duttoni. It occurs in rodents and humans. It was first described in Africa. It also occurs in the Middle East, the Mediterranean, and so on and so forth. Mites are not insects either. They are members of the order Acarina in the class Arachnida. Mites cause phenomenon skin problems, mainly characterized by severe itch as the main disease manifestation. They itch. The body of mites is unsegmented, just as is the case with the ticks. The Tegument consists of chitin, which may be sclerotized or it could consist of rigid plates. The body has numerous hairs or setae. There are four pairs of legs, similar to what we find in ticks. Scabies, we're talking about sarcoptes scabiei varieta hominis, which causes scabies. This mite is also known as the itch mite or scabies mite. Mites cause severe itch and widespread eruptions. They each may be mild to intolerably severe, particularly at night. During the day, there may be no itch, or very little itch, for that matter. Sarcoptes mite burrow is made by the adult male and female mite in the horny layer of the epidermis, and presents clinically as a straight or serpentine line. It is greyish and it measures 5-10 millimeters long. What you are talking here is that the burrow is the housing for the Sarcoptes mite, it must make a tunnel into the skin of the human being in the horny layer of the epidermis. This burrow occurs on buttocks, you can say, you'll find it on penis, elbows, knees, hands and nipples. After copulation in the tunnel, the male and the female mate there in the tunnel, the female enlarges and starts to lay eggs, 40 to 50 eggs per female in a month or more. In the tunnel, the mite will excrete feces and other waste products and these and other products cause the severe itch. Epidemiologically speaking, risk factors for scabies include overcrowding which is commonly found in schools and prisons. Take note that poverty and unhygienic practices augment the possibility of the spread of scabies. Other mites will be mentioned here Demodex folliculorum, a very small mite 0.1 to 0.4 millimeter long. These lives in the hair follicles of humans. It affects mainly eyelids and nose. The chiggers, the trombiculid mite must also be mentioned here. Severe irritation, intense severe pruritis after the larvae have fed for a period of about a week. After feeding, they drop off to the ground, they creep into the surface soil and emerge as nymphs one month later as adults. These are the so-called Trombiculid mites. The last one is Demodex folliculorum and Demodex brevis. They are found close to hair follicles on the head, nose and nasal area, folds, and ears. The larvae of these mites feed on tissue fluids. Mites and ticks are important. Lyme disease is important. Scabies is important. These are conditions which you would say are brought about by ectoparasites. Thank you very much for listening and bye bye.
