History of filariasis

Lymphatic filariasis is a neglected tropical disease caused by infection with the mosquito-borne, thread-like, parasitic filarial worms Wuchereria bancrofti, Brugia malayi and B. timori.

In Egypt, nocturnally periodic bancroftian filariasis has been endemic since Pharaonic times. The first written documents of filariasis come from the ancient Greek and Roman writers who could differentiate between the similar symptoms of leprosy and filariasis.

Jan Huygen Linschoten during his trip to Goa between 1588 and 1592 first documented the disease symptoms and wrote that inhabitants ‘‘all born with one of their legs and one foot from the knee downwards as thick as an elephant’s leg.’’

Filariasis was the first human disease described in which transmission through the skin was cause by the bites of arthropods. Doctor O. Wucherer (1868) found the embryonic filarial worms in the urine of a patient in Bahia, Brazil. T. R. Lewis (1872), working in India, observed the embryos in the urine and also in the blood, and Joseph Bancroft (1878) in Brisbane, Australia first described the adult worm. The parasite has been designated Wuchereria bancrofti.

The momentous discovery of the role of the mosquito in transmitting the disease was made by the Scotsman Patrick Mansion (1877) while he was practicing medicine in the Far East with the Chinese Imperial Maritime Customs. He became interested in the disease that confronted him, including filariasis. In that disease he recognized the parasites in peripheral blood films and also in postmortems material.

Patrick Mansion noted the nocturnal appearance of the parasites in the peripheral blood and postulated that a blood sucking insect might be responsible for transmitting the infection. Manson proved the presence of the microfilaria in the mosquito Culex fatigans, thus supplying the missing link in the life cycle of the disease.
History of filariasis

Anopheles mosquitoes

Malaria is caused by a Protozoan parasites transmitted by female anopheline mosquitoes of the genus Anopheles, as they are the blood-feeders.

There are approximately 422 species of Anopheles mosquitoes throughout the world. Of these, approximately 75 are considered to be important vectors of malaria.

Malaria is primarily transmitted in tropical or subtropical regions by the bite of an infected Anopheles mosquito. As insects are night-active, in general, the bite takes place between sundown and sunrise, specifically inside houses or other kinds of living spaces.

Anopheles can be distinguish from other adult mosquitoes by the way that the female, when taking a blood feed, inclines her whole body at an angle to her victim, whole in the other, culicine mosquitoes, the body is parallel to the skin surface.
Anopheles mosquitoes

Basic information about Zika fever

Zika is spread mostly by the bite of an infected Aedes species mosquito (Aedes aegypti and Aedes albopictus). The Zika virus, first identified in Uganda 1947, is transmitted by the same type of mosquito that carries dengue fever, yellow fever and chikungunya virus.

The viral disease has spread by outbreaks to many different countries, with an ongoing outbreak in Brazil and Puerto Rico; the first diagnosis of Zika virus in the U.S. occurred in Harris County (Houston), Texas, in January 2016.

A mosquito bites an infected person and then passes those virus to other people it bites. These mosquitoes are aggressive daytime biters. They can also bite at night. Zika can be passed from a pregnant woman to her fetus. Infection during pregnancy can cause certain birth defects.

Aedes aegypti

For most people it is a very mild infection and isn't harmful. However, it may be more serious for pregnant women, as there's evidence it causes birth defects – in particular, abnormally small heads (microcephaly). There is no vaccine or medicine for Zika.

Many people infected with Zika virus won’t have symptoms or will only have mild symptoms. The most common symptoms of Zika are: fever, rash, joint pain (with possible swelling, mainly in the smaller joints of the hands and feet), conjunctivitis (red eyes), itching all over the body. Other symptoms include: muscle pain, headache.

 The virus causes born defects in babies born to some infected pregnant women. The CDC has confirmed Zika can spread through sex, usually after a person traveled to an area where Zika has broken out, got the virus, and gave the virus to a sex partner who did not travel. Infected women and men can both pass the virus to sex partners -- even if they haven’t shown symptoms of infection
Basic information about Zika fever

Reference
https://www.cdc.gov/zika/about/index.html 
http://www.webmd.com/a-to-z-guides/zika-virus-symptoms-prevention#1 
http://www.nhs.uk/Conditions/zika-virus/Pages/Introduction.aspx 
http://www.medicinenet.com/zika_virus/article.htm

Dengue fever

Dengue fever outbreaks have been documented on every continent except Antarctica. Dengue fever is transmitted to humans by the being of an infected mosquito.

Transmission means the virus is being passed or spread to someone else. Dengue virus (DEN) is a small single-stranded RNA virus comprising four distinct serotypes (DEN-1 to -4).

These closely related serotypes of the dengue virus belong to the genus Flavivirus, family Flaviviridae. There are three major illness caused by Flaviviridae: tick-borne encephalitis virus, Japanese encephalitis and dengue fever.

The various serotypes of the dengue virus are transmitted to humans through the bites of infected Aedes mosquitoes, principally Ae, aegypti.

This mosquito is a tropical and subtropical species widely distributed around the world mostly between latitudes 35 °N and 35 °S.

Dengue hemorrhagic fever is a severe often fatal, febrile disease caused by dengue viruses characterized by abnormalities of hemostasis and capillary permeability that leads, in severe cases, to a protein-losing shock syndrome.

A person can get dengue fever four times in his or her lifetime, although a person never gets the same dengue infection twice.
Dengue fever

What are the symptoms of malaria?

Malaria is an important cause of death and illness in children and adults, especially in tropical countries. 

Malaria is caused by infection of red blood cells with protozoan parasites of the genus Plasmodium. There are four species of plasmodium protozoa involved: vivax, falciparum, malariae, and ovale.

The parasites are inoculated into the human host by a feeding female anopheline mosquito.

The signs and symptoms of malaria might be vague, but fever is generally present. The first symptoms of malaria are non-specific and similar to the symptoms of a minor systemic viral illness.

Fever is the most prominent symptom which is often accompanied by headache, lassitude, fatique, back pain and muscle and joint aches, usually followed by chills, perspiration, anorexia, vomiting, diarrhea, nausea, increased sweating, and worsening malaise.

Cough and shortness of breath are common. When synchronous infections develop, each species of Plasmodium causes a characteristics pattern of periodic fever.

In addition to these symptoms of uncomplicated malaria, other manifestations may develop that signal severe malaria, which is almost due to Plasmodium falciparum.

These include confusion or drowsiness with prostration, together with severe manifestation such as cerebral malaria, severe anemia and others.

Untreated Plasmodium falciparum infection can lead to coma, renal failure, pulmonary edema and death. The other three forms of malaria (vivax, ovale and malariae) are rarely life threatening.
What are the symptoms of malaria?

Filariasis*

Filariasis
Filariasis is a helminthic infection found principally in tropical and subtropical areas in Africa, and in the South Pacific regions. The disease is transmitted from man through several genera and species of mosquitoes. The acute disease is manifested by recurrent chills and fever and by visible swelling or nodules of the lymphatics and redness of the overlaying skin due to parasitic involvement.

The illness usually subsides gradually with or without therapy. But in those who have been repeatedly infected and are chronically ill, the inflammatory reaction and scarring of the tissues surrounding the vessels may impede the flow of lymph and blood, and mammoth enlargement (“elephantiasis”) of the arms, legs, scrotum and breasts can occur. During World War II approximately fifteen thousand American military personnel became infected, but prompted withdrawal of these patients from the endemic zones prevented chronic disease and elephantiasis.

Filariasis was the first human disease described in which transmission through the skin was cause by the bites of arthropods. Doctor O. Wucherer (1868) found the embryonic filarial worms in the urine of a patient in Bahia, Brazil. T. R. Lewis (1872), working in India, observed the embryos in the urine and also in the blood, and Joseph Bancroft (1878) in Brisbane, Australia first described the adult worm. The parasite has been designated Wuchereria bancrofti.

The momentous discovery of the role of the mosquito in transmitting the disease was made by the Scotsman Patrick Mansion (1877) while he was practicing medicine in the Far East with the Chinese Imperial Maritime Customs. He became interested in the disease that confronted him, including filariasis. In that disease he recognized the parasites in peripheral blood films and also in postmortems material.

He noted the nocturnal appearance of the parasites in the peripheral blood and postulated that a blood sucking insect might be responsible for transmitting the infection. Manson proved the presence of the microfilaria in the mosquito Culex fatigans, thus supplying the missing link in the life cycle of the disease.
Filariasis

Malaria - Infectious disease

Malaria - Infectious disease
Malaria kills three people every minute. Each year, it is thought that as many as 2.7 million people die from malaria and between 300 and 500 million suffer potentially fatal cases. The disease threatens 2.5 billion people, almost half the world’s population.

African countries south of the Sahara desert account for 90% of all clinical cases and nearly 90% of deaths caused by malaria. Children are most vulnerable to this major killer. In rural, tropical African areas, one child in 20 dies from malaria before he or she reaches the age of five years.

What is Malaria?
Malaria is a disease, caused by any of four species of parasite that is carried from person to person by a mosquito and transmitted by the bite of an infected female Anopheles mosquito.

Malaria is primarily a disease of the blood cells and small blood vessels. By causing the cells to become ‘sticky’ and eventually to burst, it causes blockages of the small blood vessels in the major organs of the body. This can cause severe disease and death – in case of the infection with the P. falciparum species of malaria, this can occur within 24 hrs of the disease first becoming evident.

Malaria caused by the other three parasite, namely Plasmodium vivax, P. ovale and P. malariae, is much milder and does not cause death, although they cause recurrent malaria than in itself is a debilitating disease.

The malaria parasite is found mostly in the tropical and subtropical regions of the world. Mosquito breeding is severely hampered in temperatures below 20 degree C. Optimal conditions for breeding are at temperatures around 30 degree C together with humidity levels of over 60%. Consequently, temperature and humidity largely dictate whether a country is likely to experience year-round malaria, seasonal malaria or localized break through.

The severity of malaria and its incidence is governed also by the immunity levels of the host, man. Immunity depends on constant exposure to the malaria-infected mosquito. Hence war and civil disturbances leading to an influx of non-immune workers, as well as tourism, all lead to the exposure of non immune to the malaria parasite.
Malaria - Infectious disease