Yeah, the topic, filariasis, will be presented in three parts. We shall start with introduction, and then lymphatic filariasis. And then lastly, onchocerciasis. Let's look at the history. Lymphatic filariasis, has been known for the past 4,000 years. The first record of filariasis, was made by Samhita of Susruta, in the sixth century BC, who speculated that filariasis was transmitted by mosquitos. But, of course, the mode of transmission which he postulated was quite different. He put forth a theory, that mosquitos would acquire the would lay eggs in water. And by drinking that water then people would get infected. This continued to be believed for quite a long time. Until 1876, when Bancroft discovered adult form of the in human. This was followed by Manson, who afters several years of study was able to demonstrate the lifecycle, indicating that mosquitoes were involved. And that hydroceles and elephantiasis, which initial were believed to be due to unknown reasons, were attributed to filariasis. 1926, Robies, finally described the development, and the transmission of onchocerciasis in blackflies. And this was followed by oblong lifecycles of insects. [INAUDIBLE] said that Manson is the one who was able to demonstrate that, to ensure that there was an connection between insects and human parasitic diseases. How about filariasis, this is a friction by parasitic nematodes, which involves vertebrate definitive host, and arthropod vectors as intermediate hosts. Characteristic feature of the parasite is the microfilaria larvae, which is common to all these species here. The main parasitic species are the vectors, include wuchereria bacrofti, which is transmitted by mosquito species, brugia malayi by mosquitos, onchocerca volvulus transmitted by simulium species, loa loa by chrysops, mansonelle species by culicoides species, and dracunculus medinesis by copepods. This is a rough sketch of the lifecycle of the filarial parasite. We starting from the period of ingestion here, where by the vector, we normally check the microfilaria during blood feeding. The microfilaria would enter the gut, from where then would penetrate the gut of peritrophic membrane, to enter the thoracic muscles. After going through a process of metamorphosis, which you will change in form, they will then become the first stage larvae, which as you can see looks like a sausage. So this is sometimes called the sausage stage. This ultimately morphs, into second larva stage, and finally into third larva stage, which is also the infective stage. During the next biting period, this is passed to the human, through the wound, caused by the biting. In this case, the microfilaria, the infective stage, crawls and enter the body through the wound. And once in the human body then, then it goes through a maturation for about a year, which involves two months. The others, finally settle, depending on the species, for. That settle in the lymphatics. When in case of they settle in the cutaneous tissue. Settle in the cavities, the cavities from the sites. Then after some time, these two mate, this is the female and this the male. The male is usually half the size of the female. These will then mate. And, the female adult, then, will produce eggs, which will develop in the uterus. And from that they leave that as microfilaria, which will then enter the bloodstream, and again ready for uptake by the diptera host.