Biology

Arthropods are the most abundant ecological specie in the world. They are diverse groups, with varying sizes and unique characteristics. Arthropods are invertebrates with a distinct exoskeleton, segmented body and numerous appendages. They are covered in cuticles that are made up of mineralized calcium carbonate and alpha-chitin which is a glucose derivative inhibiting growth. This in turn is replaced via molting or shedding. They have paired ventral nerve cords forming a ganglion. The heads are formed by fusion of segments while the brain is by fusion of ganglia which encircles the esophagus. Excretion and Respiration depends on the species subphylum. Circulatory system and other vital internal organs are housed in a hemocoele. Reproduction is via indirect transfer of sperm using an appendage or in the ground. Arthropods lay eggs except for scorpions.

Arthropods are mainly beneficial to man because of their role in food industry. Bees produce honey. Crustaceans are part of diverse ethnic cuisine. In some countries, insects can be eaten and has been proven to be rich in proteins and minerals. A Central American insect makes red dye cochineal that was important to the Mayans and Aztecs. Limulus Amebocyte Lysate, a clotting agent is used medically to detect cancer and spinal meningitis. It is derived from the blood of a horseshoe crab. Insects are also recognized in forensic medicine to determine the place and cause of death. Pollination, a process in which plants reproduce is probably the most important contribution of arthropods in civilization.

On the contrary, they can also infect man by carrying multiple diseases and cause serious conditions. Their bites can cause anaphylactic reaction which can be life threatening.
Worldwide

Fleas
Bubonic plague wiped out one forth of the population of Europe in the 14th century. Outbreaks were also noted in China and India, killing almost 10 million people.

Yersinia pestis, the etiologic agent is usually isolated in rodents, squirrels and dogs. The bacteria reside in their host and are thus carried from rodent to rodent by an infected flea. It can cause disease if the bacteria get in contact with the skin directly or by a bite of an arthropod.

Patient often presented with headache and fever. Black discoloration of the skin is attributed due to hemorrhage. Death can ensue in days without treatment.

Ticks and Deerflies
Tularemia, a disease like Bubonic plague can be transmitted through a bite of ticks and deerflies or by handling rabbits.

Franciscella tularensis is an extremely virulent bacteria that can cause pneumonia and ulceroglandular diseases.

Mosquito
Encephalitis ( Western Equine Encephalitis, Eastern Equine Encephalitis, Venezuelan Equine Encephalitis)

Alpha viruses belong to the family of togaviridae. These viruses are mosquito-borne. When a person is bitten by an infected mosquito, the virus travels into the blood stream then to the brain causing headache, fever, altered level of conciousness and neurologic diseases.

Yellow fever
Flavivirus is usually transmitted to canal workers by a bit of a mosquito. The patient will develop jaundice, fever, nausea and vomiting a week after a bite.

Dengue Fever
This is also known as painful fever. The patient usually complains of joint pains and severe headache. This is more commonly found in tropic areas. Dengue Hemorrhagic Fever is a newer, more aggressive variant of DF. Patients die of shock due to bleeding episodes.

Malaria
This is a febrile disease caused by different species of Plasmodium. The Plasmodium specie undergoes sexual division in the anopheles mosquito. Once the sporozoites are introduced into the human the life cycle of the protozoa continues.

The patient typically presents with chills and high fever that are episodic in nature. Depending on the type of Plasmodia, the timing of the spikes occurs.
Sand flies

Leishmaniasis
Leishmania is zoonotic and is usually carried by rodents, dogs and foxes. The transmission to human is usually by a bite of an infected sand fly. It can cause Cutaneous Leishmaniasis or oriental sore. Visceral Leishmaniasis typically presents as severe abdominal pain, weight loss and fever. Liver failure may ensue then death.

TseTse Fly
African Sleeping Sickness
Trypanosoma gambiense or Trypanosoma rhodesiense are usually transmitted by a bite of a tsetse fly. The trypomastigote spreads into the blood stream to the lymph nodes then to the brain.

South Texas

Mosquito
Since South Texas is subtropic, mosquitoes are usually the primary vectors of diseases in that area. Encephalitis had been one of the most recognized illnesses in the entire Texan region. Culex quinquuefasciatus and Culex tarsalis are known to be vectors for West Nile, St Louis encephalitis and western equine. The tree-hole mosquito is the vector for La crosse virus.

Sanitation, control, public awareness and education are important means to prevent spread of viral and bacterial diseases. Arthropods life cycle and diversity make it almost impossible to eradicate totally the possibility of insect-borne diseases. All means should be exercised to protect our selves from being bitten of infected.

The government should also provide adequate health measures such as vaccinations and antibiotics to protect the people. This will minimize epidemics and catastrophic events that can hurt the country.