Malaria - Basics
- Malaria is a potentially life threatening parasitic disease. It is caused by parasites known as Plasmodium vivax (P.vivax), Plasmodium falciparum (P.falciparum), Plasmodium malariae (P.malariae) and Plasmodium ovale (P.ovale)
- It is transmitted by the infective bite of Anopheles mosquito
- Man develops disease after 10 to 14 days of being bitten by an infective mosquito
- There are two types of parasites of human malaria, Plasmodium vivax, P. falciparum, which are commonly reported from India.
- Inside the human host, the parasite undergoes a series of changes as part of its complex life cycle. (Plasmodium is a protozoan parasite)
- The parasite completes life cycle in liver cells (pre-erythrocytic schizogony) and red blood cells (erythrocytic schizogony)
- Infection with P.falciparum is the most deadly form of malaria.
Symptoms of Malaria
- Typically, malaria produces fever, headache, vomiting and other flu-like symptoms.
- The parasite infects and destroys red blood cells resulting in easy fatigue-ability due to anemia, fits/convulsions and loss of consciousness.
- Parasites are carried by blood to the brain (cerebral malaria) and to other vital organs.
- Malaria in pregnancy poses a substantial risk to the mother, the fetus and the newborn infant. Pregnant women are less capable of coping with and clearing malaria infections, adversely affecting the unborn fetus.
Symptoms of severe and complicated Malaria
The priority requirement is the early recognition of signs and symptoms of severe malaria that should lead to prompt emergency care of patient. The signs and symptoms that can be used are non-specific and may be due to any severe febrile disease, which may be severe malaria, other severe febrile disease or concomitant malaria and severe bacterial infection.
The symptoms are a history of high fever, plus at least one of the following:-
- Prostration (inability to sit), altered consciousness lethargy or coma
- Breathing difficulties
- Severe anaemia
- Generalized convulsions/fits
- Inability to drink/vomiting
- Dark and/or limited production of urine
Patients with prostration and/or breathing difficulties should, if at all possible, be treated with parenteral antimalarials and antibiotics (injections or infusions). Oral treatment should be substituted as soon as reliably possible. Frequent monitoring of laboratory parameters is essential – blood sugar, blood urine, fluid balance, associated infection, etc. Drugs that increase gastro intestinal bleeding should be avoided.
Risk for severe complications
- In areas of low transmission – all age groups are vulnerable but adults develop more severe and multiple complications. The transmission pattern in most parts of India is usually low, but intense transmission is seen in north-eastern states and large areas of Orissa, Chattisgarh, Jharkhand and Madhya Pradesh.
- In areas of high transmission – children below 5 years, visitors, migratory labour.
- Association of pregnancy- Pregnant women are less capable of coping with and clearing malaria infections, adversely affecting the unborn fetus.
Vectors of Malaria
- There are many vectors of malaria
- Anopheles culicifacies is the main vector of malaria
- It is a small to medium sized mosquito with Culex like sitting posture
1. Feeding habits
- It is a zoophilic species
- When high densities build up relatively large numbers feed on men
2. Resting habits
- Rests during daytime in human dwellings and cattlesheds
3. Breeding places
- Breeds in rainwater pools and puddles, borrowpits, river bed pools, irrigation channels, seepages, rice fields, wells, pond margins, sluggish streams with sandy margins.
- Extensive breeding is generally encountered following monsoon rains.
4. Biting time
- Biting time of each vector species is determined by its generic character, but can be readily influenced by environmental conditions.
- Most of the vectors, including Anopheles culicifacies, start biting soon after dusk. Therefore, biting starts much earlier in winter than in summer but the peak time varies from species to species.
Malarial incidence in Indian states
Malaria in India is mainly caused by two major malaria parasites namely Plasmodium falciparum and Plasmodium vivax (though cases of malaria from Plasmodium ovale and Plasmodium malariae have also been reported from some parts of the country). P. falciparum (Pf ) and P. vivax (Pv) are the most common species causing malaria in the country. While P. vivax is more prevalent in the plains, P. falciparum predominates in forested and peripheral areas. The disease is transmitted by nine Anopheline species out of which the six primary vectors are Anopheles culicifacies, Anopheles stephensi, Anopheles dirus, Anopheles fluviatilis, Anopheles minimus and Anopheles epiroticus (previously known as Anopheles sundaicus ).
Key characteristics of these vectors are summarized below.
- An. culicifacies is widespread in peninsular India. It is the main vector of malaria in rural plains areas and peri-urban areas. It is found in a variety of natural and man-made breeding sites. It is highly zoophilic as a result of which the presence of a high density of cattle relative to that of humans limits its vectorial capacity.
- An. stephensi, which often shares breeding sites with An. culicifacies has developed a strong propensity for artificial containers, and is responsible for malaria in urban and industrial areas.
- An. fluviatilis is the main vector of malaria occurring in hilly areas, forests and forest fringe areas in many states, especially in the eastern part of the country.
- An. minimus is the vector responsible for malaria occurring in foothills of north-eastern states of the country.
- An. dirus, an important forest vector in the North-East, is well known for its exophilic behaviour.
- An. epiroticus, a brackish-water breeder, is restricted to causing malaria in the UT of Andaman & Nicobar Islands.
At present, malaria affects all population groups in the country, regardless of gender or age, although children and pregnant women are at higher risk. The majority of malaria in India is reported from the eastern and central part of the country and from states which have large forest, hilly and tribal areas. These states include Odisha, Chhattisgarh, Jharkhand, Madhya Pradesh, Maharashtra and some north-eastern states like Tripura, Meghalaya and Mizoram. These states have more or less perennial transmission of malaria due to a number of factors, such as presence of large conflict-affected, hilly and forest areas with poor access and inadequate health infrastructure. Additionally, there is low community awareness on malaria prevention and control among the tribal population in these areas which makes the task of transmission reduction even more challenging.
During the months from June to September, the country experiences the monsoon season characterized by heavy rains across different states of the country. It is during these months that maximum transmission of malaria takes place. In the immediate post-monsoon period from October to December, collection of rainwater in pits and puddles promotes mosquito breeding and subsequently the transmission of malaria.
Source: National Vector Borne Diseases Control Program, Ministry of Health & Family Welfare
- Operational Manual for Malaria Elimination in India
- Training Module for ASHAs on Malariology
- Guidelines for diagnosis and treatment of malaria in India
- Malaria Handbook for NGOs
- Corporate guidelines to confront Malaria
- National Framework for Malaria Elimination (NFME) in India 2016 – 2030
- National Drug Policy for Malaria