Discuss the diseases caused by other vectors

Discuss the diseases caused by other vectors.

Other vectors of concern in displaced population camps those can cause diseases are:

1. Lice : among the species of lice, only body lice are vectors of diseases that can Cause epidemics. Migrating populations easily transport body lice from their places of origin. Body lice are common where a large number of people live in unclean, crowded conditions and they can transmit pathogens for the following disease:

a. Epidemic typhus is a highly contagious disease, which can be transmitted by contaminated lice faeces penetrating the skin while scratching

b. Relapsing fever can be transmitted by crushed lice penetrating the skin while scratching.

c. Bites of body lice can cause skin irritation leading to various skin infections.

2. Mites : mites commonly cause scabies and other skin infections in displaced populations, particularly children. Overcrowding and poor personal hygiene favour the spread of mites within a refugee population.

3. Ticks : ticks are usually not a problem in camp settings. But they can transmit several diseases, (e.g., Q-fever, hemorrhaegic fever, and tick-borne relapsing fever)

4. Bedbugs: bedbugs can become a great nuisance after displaced population camps have been established for several months. Bedbug bites cause significant discomfort and loss of sleep. In heavily infested areas, young children may show signs of anemia.

Discuss the diseases caused by other vectors
                                   Discuss the diseases caused by other vectors

5. Cockroaches : cockroaches contaminate unprotected food and may transmit various pathogens including poliomyelitis virus, amoebae and intestinal viruses.

6. Snails : snails are intermediary hosts for the schistosoma flukes that cause urinary schistosomiasis and intestinal schistosomiasis.

Discuss the factors that make displaced populations more susceptible to vector borne diseases.

Displaced populations often have an increased risk of vector-borne diseases, even for diseases that may not have been present in the area before they arrived. Therefore, just because there has been no history of a particular disease outbreak in the area does not mean that it can never occur. Factors that make displaced populations more susceptible to vector-borne diseases include the following:

1. Immunity and Disease Status: Stress, lack of good nutrition, and lack of previous exposure to the disease will lower a population’s immunity to vector-borne diseases. This is especially true for malaria when a non-immune population has moved from urban or highland areas to lowland areas that are warmer or wetter.

In urban or highland areas there may be very little exposure to malaria, whereas in warmer climates, there is an increased chance for the disease to be transmitted. When the weather is wetter than where the non-immune population came from, the vector populations increase rapidly.

Displaced populations may also transfer certain parasites and diseases from their former homes to new locations where they multiply and spread. This makes the vectors and humans at the new location susceptible to diseases they would not normally be subjected to.

Vector Borne Diseases

2. Increased Exposure to Vectors: Displaced populations may be more exposed to vectors because of the following reasons:

1. Overcrowding makes it easier for lice and mites to spread from person to person. It also increases the chance that there is an infectious human (e.g., a person with lating yellow fever virus, and a nonimmune susceptible host, both living within the 50 meter flight range of the mosquito vector, Aedes aegypti).

2. Poor housing results in closer contact with sandfly vectors of leishmaniasis, flea vectors of rodent borne diseases, or tick-borne relapsing fever.

3. Increased Number of Breeding Sites

a. Mosquito populations can multiply in great numbers in poorly drained water distribution points. There may be an increased number of breeding sites, either due to more pools of water or more domestic water containers. This can
significantly increase the incidence of mosquito-borne diseases, as follows:

(i). More water-storage containers increase breeding of the dengue fever vector Aedes aegypti.

(ii). More water-filled pit latrines increase breeding of the encephalitis vector Culex quinquefasciatus.

(ii). More groundwater pits, ponds, and footprints increase breeding of the malaria vector Anopheles gambiae.

b. While evacuation sites and newly established camps may have severe problems with flies, lice, and mosquitoes, problems with rodent populations usually takes some time to build up. Poor storage or disposal of food will increase the rodent population. These rodents bring fleas and possibly diseases.

c. Flies are attracted to areas with food and wastewater disposal problems, especially around feeding centres. Fly problems are often severe at the very beginning of the camp, before sanitation systems can be established.

d. Natural disasters (e.g., El-Nino floods and hurricanes in 1997-98) may change the environment and increase the breeding sites of other vectors of less urgent concern, eg. ticks, tsetse flies, etc., resulting in less common disease
outbreaks including viral haemorrhagic fevers.

4. Temporary Nature of the Camp Site and Reduced Peri-Domestic Hygiene:
The temporary nature of a refugee camp means that it is not intended to be “home” for long. Displaced populations may not care as much to protect themselves or their household from vectors or pests as they normally would. They may be tooworried about stresses of their situation, such as lack of resources, to beconcerned about a few mosquito bites or accumulation of refuse. With the disturbed community structure and huge numbers of new neighbours, it may be difficult to develop a “community responsibility for sanitation.

5. Interruption of Vector Control Measures: In emergencies, vector control programs may lack resources to support the control measures (chemicals may be too costly). As a result, epidemics of vector-borne diseases may occur once routine vector control measures (e.g. insecticide spraying) and health careservices are disrupted.

6. Access to Basic Treatment: Epidemics can occur amongst vulnerable displaced and host populations in complex emergencies due to poor access to effectivetreatment. In complex emergencies, a general break down of the health infrastructure is common, possibly compounded by gradual deterioration over many years. In the case of displaced populations, health services often becomeoverwhelmed and many cases simply go undetected and untreated.

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