published on 20 September 2005 in life
The disasters epidemiology
The modality study and the death entity (mortality rate), wounded entity (morbidity) and disease presented in a population hit by a catastrophic event from a natural origin which is called epidemiology disaster. It is necessary to considerate how many people suffered from traumas such as breaches, bruises, injuries or scalds.
Generally it is not possible to define rules on medical consequences when earthquakes, seaquakes and floods happen. It is possible to evaluate that on a world wild level scale floods cause more victims than other catastrophes and the values are increasing, even if in industrialized world, the risk reduction lowered the cyclone, hurricane and tornado victims.
More or less the total number of the traumatic wounds are higher than death ciphers in a few cases such as earthquakes, hurricanes and tornadoes, whilst there are more dead than wounded people in many disasters such as landslides, avalanche, volcano eruptions, floods and seaquakes.
In most of these disastrous events there are vulnerable groups of people such as ancient, handicaps and kids. The instantaneous major medical needs expect procurement of food and lodgements for those who don’t have a place to stay, to oversee the affected population movements, to monitor and control transmittable disease and dead burials.
Medical emergency and diseases
The medical emergency phases
The emergency schedules the immediate utilization of all the amenable resources and foresees the deficiency of sedatives and analgesics, anaesthetics, antibiotics, vaccines, syringe and hypodermic needles, antiseptics, bandages, sticks to immobilize fractures and substances for water sterilization. These are transported very quickly by helicopters to hospitals that need them and beyond this, doctors come from the outer part that hasn’t been affected. The camp hospitals are organized 24 or more hours later a catastrophe and they are necessary for medical assistance in a second phase of emergency management.
The disease problem
The transmission of infective and contagious diseases could increase after a disaster because there could be a hydraulic net contamination following a sewerage damage, overcrowding and consequent hygienic loss on the camps where the evacuated population lives. Besides many programmes are interrupted by the disease superintendence and this gives problems to places where the endemic diseases were under control.
Epidemic or endemic disease?
A disease can be epidemic, endemic or sporadic.
An epidemic disease (epidemic or epizootic) affects a superior number of people that we can imagine in that zone and in a determined period of time (the rabies outbreak in Italy for example). If there is a big outbreak in a large geographic zone and it affects many people it is called pandemic.
An endemic disease instead (endemic or enzootic) is constantly present in a certain geographic zone or in a population with many or less cases, it is a morbid disease such as malaria in the tropical areas for example.
A disease can be sporadic because it shows up in an irregular and unforeseeable way on the territory and in time. It verifies in not many cases and with low frequencies such as some leucosis forms that affects bovines.
Cholera and affinities
Many months might pass before having potable water in New Orleans and in the meantime the flood caused 5 dead between evacuees that entered in contact with putrefied water. This news was published on the 7th of September and the victim total count will be completed within a few weeks. The deceases are caused by Vibrio vulnificus, a cholera’s “cousin” germ. Usually it contaminates food not conserved very well but it can penetrate in open lacerations and when it gets in contact with blood, it causes death in 50% of the cases. Besides on the 9th of September some info that came from medical sources from the United States counted up to 160 gastrointestinal infection cases probably caused by a Vibrio too.
Let’s see which human diseases are caused by bacteria that belong to the Vibrio specie since the environmental conditions of a territory following a hurricane and a flood (putrefied and stagnant waters) are ideal for the growth of these pathogens. The Vibrio genus has different species, some cause infections that could be seriouse. The Vibrio cholerae infection causes Cholera, a very dangerous disease that disappeared in the occident industrialized countries but widespread in the hot zones of the Third World. The microorganism responsible for Cholera seems like a curved stick, it is defined as Gram-negative for the colour it assumes if put on a slide and seen on a microscope. As a convention the bacteria are divided into two groups according to the holding and gathering capacity of some colorants. This method has been invented in 1884 by a Danish doctor Christian Gram. The Gram-positive bacteria become violet , whilst Gram-negative such as V. cholerae become red.
The V. cholerae is mobile, facultative anaerobe and a weak halophile. The facultative anaerobe microorganisms can live without atmospheric oxygen but if there is oxygen they grow faster and stronger. Besides the V. cholerae is a bit halophile which means it stands salty concentrations where it lives (water) up to 8% maximum.
It is possible to be infected if you drink contaminated water and it is very contagious so it is easily transmitted from ill people. There are two infection types: cholera and an gastrointestinal infection form which is lighter.
Cholera has an incubation period that goes from 6 hours to 5 days and initially it starts off with an abdominal ach, diarrhea and inappetency. In very little time these symptoms degenerate into a dehydration serious form that can bring to death if not taken care of.
The gastroenteritis causes very similar problems to Cholera but less serious and generally it is possible to recover within three weeks according to the affected person.
The Nile Fever
In the New Orleans zone 16 new cases of Nile Fever appeared ten days later Hurricane Katrina’s arrival. It is called Nile Fever but it isn’t a typical disease that affects only the population around the African river. According to data communicated in the year 2002, it is a morbid that affected Europe, Africa, Middle East and United States. The pathogen is an organism who causes the disease, it is a virus transmitted by mosquitoes when they bite their victims. Mosquitoes can assume virus lethal doses biting many times infected birds, such as pigeons. Since pigeons are normal city habitants they can be affected by the Nile Fever too, it is simple to intuit an epidemic spread danger in the centre of a city infested by mosquito carriers of this virus. It is presumed that this virus is part of the Togaviridae family, more precisely it is a flavivirus. The disease generally causes indisposition, very similar to a common flu but in some conditions it can attack the central nervous system provoking dangerous cerebral infections. The flavivirus is generally found in Africa, in the west part of Asia and in the Middle East. Clinical data show it has been commonly found in human beings, birds and other vertebrates. Between 1999 and 2002, 18 deaths caused by the West Nile virus were registered in the United States, unfortunately the mosquito who transports it is the Culex genus and survives at cold temperatures in the adult stadium. The temperature increasing in the Occidental hemisphere of the planet might have helped the Culex mosquito survival which being alive transporters of virus facilitate its resistance and diffusion.
The Vibrio vulnificus infection
These vibrios have been discovered at first in 1976 by analysing a blood sample that came from an infected human being. These are capable to invade and destroy soft tissues, penetrate in wounds and cause septicaemia (bacteria that replicate themselves actively in blood) and death in the most sensitive victims.
In the septicaemia infection type there are epidermal lesions that develop on legs and arms that could be eczemas, blisters and ulcers. Unfortunately when V. vulnificus hits with a septicaemia form it can cause death from 40 – 60% cases.
There is an entericus kind that makes people sick following raw oysters indigestion. Adults generally aren’t exposed to this kind of risk but there are some exceptions such as old people, fellows that have hepatic problems and immune depressed (sick of AIDS). There haven’t been cases infected by V. vulnificus in Italy.
Leptospirosis is an infection that has a bacterial origin and affects humans and animals, it is caused by a microorganism family of the Leptospira genus. The family is called Spirochetaceae, bacteria with an itsy-bitsy and thready body that live in water and in humid environments. Normally they can live as mice, rats, pigs, coypus and other mammals guests. These animals, introduce the Spirochetaceae in the environment (water, mud) through urine.
How can man be infected?
These microorganisms penetrate through the skin if wounds or lacerations are presented. The environmental characteristics that help the Leptospiras survival and the disease transmission are similar to the ones verified in New Orleans following the water invasion: an elevated humidity grade, an environmental temperature between 20 and 30 °C, a humus presence, rubbish and organic substances, water and stagnant mud presence and zones not directly illuminated by the sunlight.
Bacteria can attack our organism by the consumption of very contaminated water and aliments (perhaps by the urine of animals that aren’t abundantly ill but casual carriers) even if the gastric juice of our stomach should defend us in an efficacious way from the infection. In alternative the Leptospiras can penetrate in our body through the eyes and nose mucosa. The incubation is from two day to four weeks long. The infection symptoms are: sudden high fever following shivers, headaches, muscle aching, vomits, diarrhea. The victim can get better in short time but he could have a serious relapse with kidney or meningitis complications. If the disease is taken care properly it can persist from a few days to 3 weeks, but if it isn’t cured it can take many months to overcome it completely.
Leptospirosis statistic data, show that sanitary emergencies following most of all floods, the main infection victims are civil guards because they have to clean up houses from the water, take away mud and debris or work on the bank adjustment.
Sceneries and rescues
Following Katrina’s passage
The zones hit by hurricanes during their entire evolutions are numerous and includes Florida, Mississippi, Alabama, the occidental Panhandle Florida, the occidental part of Georgia, the Tennessee and Ohio valleys, a part of the big Lakes region, the Appalachian chain and in particular Louisiana with huge and serious damages to New Orleans and adjacent areas. To understand better the inundation seriousness it is sufficient to remember that both dams of the city didn’t resist the wind power and the water mass covered up 80-90% of the territory from 7 to 8 metres high. The victim number is sadly distributed in every State that has been hit, but surely New Orleans had the highest death and destruction concentration.
The rescues were operative a bit before Katrina’s arrival in Louisiana, the Federal Emergency Management Agency called immediately a trained staff for emergencies and logistic equipments. Many mobilize such as the National Guard, the United States Marine, the Coast Guard and the Army, the American Red Cross (ars), and many other organisations that don’t have anything to do with militaries and governments. They tried to send many types of rescue means as possible to New Orleans such as ambulances, camp hospitals, tents, food and water supplies, clothes, blankets, camp morgues, transport means with mortuary rooms.
Hospital patients and old people in sanitarians were the most affected because they had bigger evacuation problems than healthy adult citizens. The immediate sanitary emergency is represented by wounded people that need to be rescued and to be transported in improvised hospital structures that were up to one-hundred more or less.
Following a natural catastrophe with a deep impact, a city remains completely paralyzed, and it isn’t easy to manage the rescues and the public order. The survivors, desperate and under choc, were homeless and without food. There have been despoilments in a few urban zones that haven’t been submersed, burglary in stores and supermarkets. The police forces tried to keep under control the social situation carrying out difficult and complicated assignments. Numerous unharmed inhabitants refused to leave their houses exposing themselves this way to dangers and falls, accidents and healthy problems.
Ten days later the hurricane’s disaster more or less, New Orleans is still under water despite the aspiration job done by enormous pumps to dry the city. The news on the 8th of September said that there are alligators swimming around the flooded part of the city looking for food such as dead animals and human bodies; this dangerous predator invasion caused panic and annoyance to those who were barricaded in their houses and to the rescuers.
This situation brought up to a public sanitary emergency estate proclamation for the entire zone afflicted by the catastrophe, within a week 40 sanitary structures more or less have been instituted to face the disaster and improve the population rescue quality. On the 23rd of September the ascertained number of the victims was more than a thousand and 800 dead were counted in Louisiana.
Written by Eliana Marchisio