Factors that favor the spread of malaria Malaria is more commonly seen in rural areas in India. In these areas, hygienic conditions are not good. One invariably finds places which do not have proper drains to drain water, and that causes stagnation of water. The ill–ventilated and ill–lit houses provide ideal indoor resting places for mosquitoes. Malaria is acquired in most instances by mosquito bites within the houses.
Many of the people in rural areas sleep outdoors, not using mosquito nets makes them more prone to mosquito bites. The spraying of insecticides, if not undertaken on a regular basis, also favors the spread of malaria.
Influence of the environment on the occurrence of malaria Malaria is more commonly seen in the monsoon months. In most parts of India, the maximum prevalence is from July to November. Rain in general provides opportunities for the breeding of mosquitoes, and may give rise to epidemics of malaria. Rain increases atmospheric humidity which is necessary for the survival of mosquitoes. The atmospheric humidity has a direct effect on the length of the life of the mosquito. When the relative humidity is high, mosquitoes are more active, and they feed more voraciously. If humidity is low, mosquitoes do not live long. The majority of Indian mosquitoes bite at night.
Malaria can be transmitted by blood transfusion. Blood transfusion poses a problem because the parasites keep their infective activity for at least 14 days in blood bottles stored even at – 4°C. Care should be taken not to take blood from people with a recent history of fever. In addition, blood is tested for malaria. A pregnant women can be affected by malaria. The condition can be serious particularly if it is due to infection by the P.falciparum.
Malaria affects all age groups Malaria can be seen in all age groups. However, in some persons, the infection may not be seen. New born infants have considerable resistance to infection with Plasmodium falciparum. This has been attributed to the high concentration of fetal hemoglobin during the first few months of life, which suppresses the development of P.falciparum. The other group of individuals in whom it the infection, particularly P.falciparum may be mild are individuals with AS hemoglobin (sickle cell trait) have a milder illness with falciparum infection than do those with normal. Some of these genetic disorders are seen in areas where malaria is common and it may be nature’s way of protecting the individual from this deadly disease though at a cost.
Incubation period This period is usually not less than 10 days.