zika virus
zika virus
Zika Virus :
Zika virus has emerged from its origins in central Africa and has rapidly spread to the South Pacific and western hemisphere. A Flavivirus related to West Nile, Yellow Fever, St Louis and the equine encephalitides, Zika was first discovered in macaque monkeys in 1947 in the Zika Forest region of Uganda. Since its discovery in 2014 off the coast of South America, Zika cases have been found in 35 countries in the Americas.  As of 28 April, 2016, there have been 426 reported cases of Zika virus due to travel to endemic areas. However, local transmission within the continental United States has, as yet, not been reported. In US Territories in the Caribbean, a total of 599 cases have been reported, with 596 being locally acquired, primarily in Puerto Rico and the US Virgin Islands. Although in rare cases Zika can be spread through sexual contact with an infected person, it is usually transmitted through the bit of an infected Aedes agypti or Aedes albopictus mosquito. The illness is usually quite mild, with fever, rash, conjunctivitis and joint pain lasting a few days to several weeks or months. Often patients are not sick enough to seek medical treatment so a great many cases are not reported. It is thought that one attack confers immunity. However, cases of microcephaly, a congenital defect of cranium and brain size resulting in profound neurological defects in newborns usually resulting in death have been been positively identified as being caused by Zika infection. An autoimmune condition called Guillain-Barré syndrome, causing damage to nerve cells resulting in muscle weakness and, on occasion, paralysis and death has been linked to Zika infection. The mosquito vectors of Zika virus are peridomestic, preferring to lay their eggs above the waterline of containers, treeholes, creases in tarpaulins and other vessels that may contain water. Aedes aegypti, in particular, will lay eggs in a series of containers after feeding. Both Aedes agypti and Aedes albopictus will feed day or night when a potential host comes within their limited flight ranges. Aedes agypti has more of a tendency to enter and stay within houses if conditions are proper. This species is exceedingly skittish, often leaving its host prior to taking a full blood meal when the host moves. Both mosquitoes also seem to prefer feeding on the host’s lower extremities. Traditional outdoor ULV sprays are ineffective against Aedes agypti, it being difficult to obtain contact with the spray droplets in flight due to its cryptic habits. Some success with ULV sprays has been obtained against Aedes albopictus in urban areas, while suburban areas remain refractory. The primary means of controlling both species is to eliminate their oviposition habitats by removing water bearing containers or emptying them and scrubbing the insides to remove eggs deposited above the waterline. Personal protective measures such as application of EPA-registered repellents and wearing of long-sleeved shirts and long pants are also effective measures.  When traveling to areas endemic for Zika in the Caribbean, it is also recommended to stay in hotels with air conditioning and window and door screens to keep mosquitoes outside. If available, it is advised to sleep under mosquito bed nets.

Malaria

Malaria is an ancient disease. In all likelihood originating in Africa, it has been described by the Chinese as far back as 2700BC and the Sumerians from 1700 BC. The malaria parasite (plasmodium) is transmitted by female Anopheles mosquitoes. The term malaria is attributed to Horace Walpole in a letter from Italy in 1740 and is derived from the Italian 'mal-aria" or "bad air" because it was thought to come on the wind from swamps and rivers. Scientists conducted much research on the disease during the 1880s and early 1900s. Approximately 40% of the world's population is susceptible to malaria, mostly in the tropical and sub-tropical areas of the world. It was by and large eradicated in the temperate area of the world during the 20th century with the advent of DDT and other organochlorine and organophosphate mosquito control insecticides. An elevated standard of living, including the use of air conditioners and window screens, along with public health interventions have largely remanded malaria transmission to tropical areas. Nonetheless, it can still be found in northern Europe.

More than one million deaths and 300 - 500 million cases are still reported annually in the world. It is reported that malaria kills one child every 40 seconds. In the United States malaria affected colonization along the eastern shore and wasn't effectively controlled until the 1940s when mosquito control organization instituted Anopheles control programs. A resurgence occurred during the 1960s and early 70s in the United States due to returning military personnel from Vietnam. Minor outbreaks of locally-acquired malaria occur sporadically in the United States, but have been quickly controlled by aggressive mosquito control measures. The influx of illegal immigrants in addition to returning tourists may provide for infrequent outbreaks in the future.

Anopheles quadrimaculatus and Anopheles freeborni have been the primary vector of the Plasmodium vivax (protozoa) in the United States (Foote and Cook 1959).

Antimalarial drugs have been available for more than 50 years and recently scientists in Britain and the United States have cracked the code of the malaria parasite genome, a step that may help boost the campaign against the disease. In the meantime, active case detection

Chikungunya 

Chikungunya virus is a pathogen transmitted by mosquitoes, and has established itself in the Caribbean (approximately 350,000 suspected cases in the Western Hemisphere since December 2013). It has now resulted in 2 cases of locally-transmitted Chikungunya virus in Florida in July of 2014. As of July 22, 2014, 497 travel-related cases have been found in 35 states, Puerto Rico and the U.S. Virgin Islands. The occurrence of locally-transmitted cases causes public health officials fear to its spread and establishment in states bordering the Caribbean. The name “Chikungunya” is attributed to the Kimakonde (a Mozambique dialect) word meaning “that which bends up”, which describes the primary symptom – excruciating joint pain. Although rarely fatal, the symptoms are debilitating and may persist for several weeks. There is no vaccine and primary treatment is limited to pain medication.

The mosquito species that transmit this disease are the Asian Tiger Mosquito (Aedes albopictus) and the Yellow Fever Mosquito (Aedes aegypti). Genetically, it appears that viral strain currently spreading throughout the Americas is more easily transmitted by aegypti. Both species lay their eggs in containers such as cans, discarded tires and other items that hold water close to human habitation, but  aegypti is more geographically confined to the southeastern United States. Traditional mosquito methods of truck-mounted and aerial sprays are ineffective in controlling these mosquitoes. Removal of water-bearing containers and sanitation are key preventive strategies.