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Incubation period of malaria disease: CDC – Malaria – About Malaria

A 4-Day Incubation Period of Plasmodium falciparum Infection in a Nonimmune Patient in Ghana: A Case Report

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Open Forum Infect Dis. 2019 Jan; 6(1): ofy169.

Published online 2019 Jan 17. doi: 10.1093/ofid/ofy169

,1,2,3,4,4,4 and 5,6

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Plasmodium falciparum can cause severe infection and has the shortest incubation period compared with all the other Plasmodium species. Incubation periods of 9–14 days for the immune and 6–14 days for the nonimmune have been reported for P. falciparum. However, an incubation period of less than 5 days has not been reported, as of yet. This report presents a case of a 23-year-old nonimmune female who presented with signs and symptoms 4 days after being bitten by mosquitoes while visiting Ghana. The patient was successfully treated with a 1-day course of parenteral artesunate, followed by a 3-day course of oral artemisinin combination therapy.

Keywords: artesunate, Ghana, incubation period, Malaria, nonimmune, Plasmodium falciparum, West Africa

Plasmodium falciparum is one of the prominent Plasmodium species, transmitted by malaria-causing vectors, in Ghana [1, 2]. This Plasmodium species is responsible for the majority of the uncomplicated and severe malaria cases that are reported in clinics and hospitals throughout Ghana [3]. Among the 5 species of Plasmodium that cause human infection, P. falciparum causes the most severe form of malaria [4]. Like the other species, P. falciparum is transmitted by the bite of an infected female Anopheles mosquito; however, it has a relatively shorter incubation period than the others [5]. The incubation period for P. falciparum is 9–14 days, whereas those of P. vivax and P. malariae are 12–17 days and 18–40 days, respectively [5]. Though a shorter incubation period of 6 days for P. falciparum has been reported, especially in the nonimmune [4], an incubation period of less than 5 days has not been reported in literature. Presented here is a case of a 4-day incubation period of P. falciparum infection in a nonimmune patient in Ghana.

A 23-year-old female medical student from the United Kingdom presented to a local hospital 5 days after arriving in Ghana, with a 24-hour history of fever, chills, bodily pains, vomiting, and diarrhea. She reported a recent incident of several mosquito bites while she was sitting outside the first night she arrived in the country. The patient had never visited Africa before this trip. She had been taking 250 mg of mefloquine once a week for malaria prophylaxis but admitted to not being compliant with her medication. The patient admitted to being a cigarette smoker and to smoking about 3 packs per week. Since the onset of her symptoms, she had vomited twice and passed loose, nonbloody stool 4 times. Upon examination, the patient exhibited several insect bite marks bilaterally on the legs and a temperature of 37.8°C; she was not dehydrated, pale, or in respiratory distress. She had a flat abdomen but reported mild epigastric tenderness. Breath sounds were clear bilaterally; in addition, heart sounds were clear, with no rubs, murmurs, or gallops. The patient was conscious and oriented to time, place, and person. Her full blood count investigation revealed a hemoglobin level (Hb) of 12.3 g/dL; white blood cell count (WBC) of 8.2 × 109 µL with differentials (neutrophils 50%, lymphocytes 30%, monocytes 20%, and basophils 0%) and platelets of 158 × 109 uL. A rapid diagnostic test (RDT) was positive for malaria parasites, and malaria parasites were also seen on blood film microscopy, with a parasitemia level of 2+. Urine pregnancy test was negative, and urinalysis showed no signs of infection. The patient was diagnosed with malaria and was immediately started on artesunate injection, 160 mg Q12H. The patient was also placed on 500 mL 5% dextrose normal saline infusion, alternating with 500 mL ringers lactate infusion, for 24 hours. The patient’s fever, vomiting, and diarrhea subsided 24 hours after commencing treatment. The patient was subsequently placed on oral, adult-course artemether lumefantrine (80/480 mg, repeated every 8 hours for the first day, then twice daily for the next 2 days) and paracetamol (acetaminophen) 1 g every 8 hours for 3 days. The patient’s condition improved, and she was discharged 3 days after. The patient was re-examined a week later and found to be recovering well, with resolution of her symptoms. Before leaving Ghana, 6 weeks post–hospital admission, there was no parasite observed in her blood film microscopy, and RDT was negative.

Our patient had not visited Africa or any other malaria-endemic region of the world. Therefore, she had no form of immunity against malaria. She manifested febrile symptoms 4 days after the mosquito bites, which infected her with the malaria parasite, as evidenced by the positive P. falciparum–specific RDT.

The virulence of P. falciparum is seen in the severity of the disease [4, 6]. It has also been reported to have a short incubation period and life cycle [4, 6]. The life cycle begins with the bite from an infected female Anopheles mosquito. The sporozoites’ journey through the liver to the red blood cells which is marked by 2 important periods in the life cycle: the prepatent period (from sporozoite entry to parasite detection in the blood) and the incubation period (sporozoites to the manifestation of symptoms) [4]. The duration of these periods, especially the incubation period, is usually influenced by the level of immunity of the infected patient, antimalarial prophylaxis, and previous malaria treatment [4, 7]. The nonimmune state of our patient would have been responsible for the unusually short incubation period noted in this case [4]. Though she was on mefloquine prophylaxis, which is specific to P. falciparum [8], she was not consistent in taking the course. Though the patient had a short incubation period, her symptoms were not severe, probably because she reported to the hospital as soon as the symptoms began. She presented with the typical malarial symptoms of fever, chills, vomiting, and diarrhea [9]. The physical findings were also not remarkable, which is not uncommon, even in nonimmune patients [4]. The laboratory results also reflect the unremarkable nature of this infection, as all blood cells (leukocytes, red cells, and platelets) were within normal reference range. Usually, more severe infections, especially in the nonimmune, present with thrombocytopenia, anemia, and neutrophilia with band formation [10]. RDT was used as a diagnostic tool to diagnose malaria in this patient, and the positive RDT was confirmed with microscopy, which is indeed the best practice in laboratory diagnosis of malaria [11–13]. Though the patient did not present with severe malaria and, as per the World Health Organization guidelines, being nonimmune is not a criterion for treatment with intravenous artesunate [14], the decision to start the patient on parenteral antimalarial was because of the vomiting, as she might not have been able to tolerate oral medication. Artesunate was the parenteral antimalarial drug of choice for this patient. It is a very efficacious drug, whose rapid parasite clearance, lack of or minimal clinical side effects, and an easy administration made it a better option than quinine [15, 16].

P. falciparum malaria typically manifests within 2 months of exposure to mosquito bites and generally presents clinically in travelers after their return from an endemic region [17]. Unlike the typical incubation period, this case highlights the successful management of P. falciparum infection occurring in a nonimmune patient 4 days after being bitten by mosquitoes. The patient was successfully treated with a 1-day course of parenteral artesunate, followed by a 3-day course of oral antimalarial artemisinin combination therapy.

Potential conflicts of interest. All authors: no reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

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    WHAT YOU NEED TO KNOW ABOUT MALARIA!

    MALARIA is a severe parasitic disease widespread in countries with a tropical and subtropical climate (Asia Minor and Southeast, Africa, South America) and neighboring countries (Azerbaijan, Armenia, Uzbekistan, Tajikistan, Georgia). Malaria is characterized by attacks of fever (fever), anemia, enlargement of the liver and spleen .

    Infection occurs when bitten by malarial mosquitoes. There are 4 types of malaria: tropical, three-day, four-day and oval malaria. The most severe is the tropical form, common in African countries.

    According to the World Health Organization, currently 82 countries of the world are highly endemic for malaria and are in the process of combating it, and only 16 countries have achieved the elimination of malaria in their territories through anti-epidemic (preventive) measures, and 27 countries have received the status of “malaria-free”, confirmed by the WHO certificate. Russia is represented in the group of countries directing efforts to prevent local transmission of malaria.

    Malaria is transmitted from a sick person to a healthy person through the bites of female mosquitoes. In addition, there are two more ways of infection – through blood transfusion and intrauterine, when a woman with malaria infects her unborn child. Entered into the human body during the bite of malarial mosquitoes, the parasites circulate in the blood, and then are carried to the liver, in the cells of which they begin their development.

    The incubation period (the period from the moment of infection to the onset of the first clinical symptoms) ranges from 7 days to 1 month (in case of a tropical form of malaria, the incubation period can last up to 3 years).

    Signs of the disease – the disease begins acutely: weakness, severe headache, chills appear. Then recurring attacks of fever begin, in which the body temperature rises to 40 ° and above, and lasts for several hours. The fever is accompanied by severe chills; at the end of the attack marked sweating. Attacks are repeated regularly – after a certain time (every other day, two or three days later). When such attacks occur, you should immediately seek medical help.

    Tropical malaria the most severe form of malaria. The incubation period most often ranges from 8 to 16 days. Headache, fatigue, nausea, loss of appetite may occur 3-4 days before the development of the first clinical signs. The initial stages of the disease are characterized by severe chills, a feeling of heat, severe headache. In the absence of timely treatment, a fatal outcome occurs. Recovery depends on the correct selection of antimalarial drugs and the equipment of the clinic.

    Malaria parasites are found in the blood of a sick person and can only be detected by examining the blood under a microscope. Treatment of this dangerous disease is carried out taking into account the type of pathogen and its sensitivity to chemotherapy drugs.

    Prevention of malaria.

    All travelers to tropical countries in Africa, Southeast Asia, Central and South America are recommended to carry out specific prophylaxis of malaria by taking antimalarial chemicals. More detailed advice on dosages and regimens for taking antimalarial drugs can be obtained from the offices of infectious diseases in polyclinics at the place of residence.

    It must be remembered that during a stay in a malaria-prone country and within 3 years after returning home, in case of any increase in temperature, you should immediately contact a medical institution, informing the doctor about the fact of staying in tropical countries endemic for malaria.

    In addition to taking antimalarial drugs, it is necessary to remember about personal non-specific prevention of malaria: the use of repellents (mosquito repellents), in the absence of air conditioning in places of accommodation, windows and doors should be blocked, electric fumigators should be used to kill mosquitoes.
    People living in areas endemic for malaria should observe the following recommendations during their stay in the outbreak:

    • dress in tight, as close as possible, light-colored clothing when leaving the house after sunset;
    • apply repellents to exposed areas of the body;
    • sleep in rooms that exclude the penetration of blood-sucking insects;
    • before going to bed, treat the room with an insecticidal spray or use fumigators;
    • in the presence of a large number of mosquitoes and the impossibility of screening the windows, organize sleep under a canopy made of gauze and treated with insecticide.

    Remember! Only early detection of malaria patients will help them recover and prevent the spread of infection among the surrounding population!

    Follow all the rules for malaria prevention! Take care of yourself!

    The material was prepared by
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    Malaria

    Malaria is a protozoal disease characterized by fever, chills, enlargement of the spleen and liver, and anemia. The causative agent is malarial Plasmodium transmitted by female mosquitoes of the genus Anopheles.

    In Russia, in the humid subtropics (for example, Sochi), malaria was a big problem at the beginning of the 20th century until S. Yu. Sokolov took measures to drain wetlands, oil reservoirs and carry out other measures that eventually led to the destruction of breeding sites for malarial mosquitoes in the resort area. In Russia and the USSR, until the early 1950s, the incidence of malaria was massive, not only in the Caucasus, Transcaucasia and Central Asia, but also in the middle zone of the European part (the Volga region and other regions). Subsequently, malaria was practically eliminated in the USSR by 1960, but isolated cases (several dozen per year) happened.

    Epidemiology

    Malaria is one of the most common parasitic diseases. Plasmodium is carried by various species (over 50) of mosquitoes from the genus Anopheles. Infection of a person occurs when a person is bitten by an infected mosquito, as well as during a blood transfusion of a patient with malaria. Possible intrauterine infection of the fetus. A person becomes contagious when sexual forms appear in his blood.

    Symptoms and course

    Three-day malaria.

    Three-day malaria is characterized by a long benign course. Repeated attacks (distant relapses) occur after a latent period of several months (3-6-14) and even 3-4 years. In some cases, malaria can be severe and fatal.

    In first-time patients, the disease begins with malaise, weakness, headache, ache in the back, limbs. In most cases, typical attacks of malaria are preceded by a 2-3-day increase in body temperature to 38-39°C. In the future, attacks of malaria are clinically clearly defined, occur at regular intervals and more often at the same time of the day (between 11 and 15 hours). In moderate and severe course of the disease during chills, the patient has severe weakness, a sharp headache, aching pain in large joints and lower back, rapid breathing, repeated vomiting. Patients feel a tremendous chill, cold. The face turns pale. Body temperature quickly reaches 38-40°C. After the chill comes the fever. The face turns red, the skin of the body becomes hot. Patients complain of headache, thirst, nausea, tachycardia increases. Blood pressure drops to 105/50-90/40 mmHg Art. Almost all patients have moderate bloating, loose stools. An increase in the liver and spleen can be detected already in the first week of the disease. Anemia develops gradually. In the natural course of the disease, febrile attacks last 4-5 weeks. Early relapses usually occur after 6-8 weeks. after the end of the initial fever and begin with regularly alternating paroxysms, prodromal phenomena are not characteristic of them. Complications from three-day malaria are rare. In underweight individuals with overheating and dehydration, a severe course of malaria can be complicated by endotoxic shock. Combinations of malaria with severe forms of other infections or diseases can be fatal.

    Tropical malaria.

    The incubation period is about 10 days, with fluctuations from 8 to 16 days. Tropical malaria in non-immune individuals is characterized by the greatest severity and often acquires a malignant course. Without giving antimalarial drugs, death can occur in the first days of the disease. In some people who first fell ill with malaria, prodromal phenomena are noted – general malaise, increased sweating, loss of appetite, nausea, loosening of stools, a two-three-day increase in body temperature up to 38 ° C. In most cases, the onset of the disease is sudden and is characterized by moderate chills, high fever, agitation of patients, severe headache, aching muscles and joints. In the first 3-8 days, the fever is of a constant type, then it takes on a stable intermittent character. At the height of the disease, attacks of fever have some features. There is no strict frequency of onset of fever attacks. They can begin at any time of the day, but most often occur in the morning. The decrease in body temperature is not accompanied by sudden sweating. Fever attacks last more than a day (about 30 hours). During periods of chill and heat, the skin is dry. Characterized by tachycardia and a significant decrease in blood pressure to 90/50-80/40 mmHg Art. The respiratory rate increases, dry cough, dry and wet rales appear, indicating the development of bronchitis or bronchopneumonia. Dyspeptic phenomena often develop: anorexia, nausea, vomiting, diffuse epigastric pain, enteritis, enterocolitis. The spleen increases from the first days of the disease, which is manifested by soreness in the left hypochondrium, aggravated by deep inspiration. By the 8-10th day of illness, it is easily palpable, its edge is dense, smooth, painful. Toxic hepatitis often develops, but liver function is slightly impaired. From the first days of illness, anemia is detected. In the peripheral blood from the first days, plasmodia are found in the ring stage.

    Four-day malaria.

    The incubation period in cases of natural infection is 21-40 days, in cases of intravenous infection with schizonts – from several days to several months. Tissue schizogony is observed only in the incubation period. A distinctive feature of the causative agent of four-day malaria is the ability to remain in the human body for a long time (tens of years) after the illness. Prodromal symptoms are relatively rare and resemble the prodrome of three-day malaria. Characterized by typical paroxysms of fever, lasting about 13 hours, followed by their correct alternation every fourth day. The spleen enlarges slowly and is palpated only 2 weeks after the onset of the disease. Anemia in this form of malaria develops gradually and does not reach the level characteristic of three-day and tropical malaria, which is explained by the relatively low level of parasitemia. The duration of clinical manifestations of untreated four-day malaria is several months, until spontaneous recovery occurs.

    Malaria ovale.

    Endemic to West Africa. The incubation period is from 11 to 16 days. This form of malaria is characterized by a benign course and frequent spontaneous recovery after a series of attacks of primary malaria. According to clinical manifestations, oval malaria is similar to three-day malaria. A distinctive feature is the onset of seizures in the evening and at night. The duration of the disease is about 2 years, however, relapses of the disease that occur after 3-4 years are described.

    Treatment : strictly in a hospital.

    Prevention

    Methods used to prevent the spread of disease or to protect in areas endemic for malaria include preventive medicines, mosquito killers, and mosquito bite prevention products.