Top 5 Serious Diseases Affecting Children Under Five and What Parents Should Know

Author: Azuka Chinweokwu Ezeike, MBBS, FWACS (Obstetrics and Gynaecology), FMCOG, MSc (Public Health)

 Highlights

• Children under five are highly vulnerable to infections due to their immature immune systems, making early recognition of illness critical.
  
  
• Malaria, pneumonia, diarrhoea, HIV, and tuberculosis remain the leading causes of preventable deaths in young children worldwide.
  
  
• Delayed care, self-medication, and poor access to healthcare increase the risk of fatal outcomes.
  
  
• High fever, difficulty breathing, convulsions, refusal to feed, and extreme weakness are danger signs that require urgent medical attention.
  
  
• Most childhood deaths can be prevented through timely treatment, vaccination, good nutrition, and improved hygiene practices.
  
  
• Caregivers play a vital role in child survival by recognising symptoms early and seeking prompt medical care.

Introduction

Mrs M’s vibrant three-year-old left for school full of energy. By midday, she received a call from the teacher saying the child was unwell. She went to pick him up and noticed he had a high fever. Assuming it was related to teething, she gave him paracetamol.By nightfall, the fever worsened, and the child became very weak. She decided to take him to the hospital in the morning when her husband returned from his night duty post. However, the child seemed better as the fever had gone down, although he could not return to school because he was still weak. She shelved her planned hospital visit.Sadly, by the following night, the fever returned with greater intensity, and the child began to convulse. They rushed him to the hospital, but unfortunately, he died before they arrived.

Children under the age of five are more prone to illnesses because their immune systems are not yet fully developed. Every year, many children in this age group die from preventable and treatable childhood diseases. These deaths often result from a lack of treatment, delayed care, or the absence of preventive measures.

When the seriousness of a child’s illness is not recognised early, it can lead to inappropriate home treatment or delays in seeking medical care. In Mrs M’s case, she assumed her child’s illness was not serious, which contributed to a delay in hospital care. 

Sadly, such situations can have fatal consequences.Unfortunately, deaths from childhood illnesses are more common in low-resource settings, where access to timely and quality healthcare may be limited.

This article highlights the top five diseases responsible for childhood deaths worldwide, along with their treatment and preventive measures.

Common Causes of Death in Young Children

Reports from the World Health Organisation (WHO) show that diseases such as pneumonia, malaria, diarrhoea, and sepsis account for most deaths among children between one month and nine years of age.

 According to the United Nations Children’s Fund (UNICEF), the top five diseases responsible for deaths in children under five years include:

• Malaria
  
  
• Pneumonia
  
  
• Diarrhoea
  
  
• Human Immunodeficiency Virus (HIV) 
  
  
• Tuberculosis
  
  

1. Malaria in Children

Malaria is a disease caused by a microorganism called Plasmodium. It is transmitted through the bite of an infected female Anopheles mosquito. Five species of Plasmodium cause malaria in humans, but the most common and most severe form is caused by Plasmodium falciparum.

Who is affected by Malaria?

The highest burden of malaria is in the African region, which accounts for about 95󠀥％ of malaria cases and deaths worldwide. Children under five years of age are the most affected and make up nearly 75％ of malaria-related deaths. Malaria is more common among children from low-income households, in subsaharan Africa and those living in rural areas.

Symptoms of malaria in children under five

Malaria can be uncomplicated (simple) or severe (complicated).If your child develops any of the symptoms below, malaria is a possible cause: [1]

• Fever, often worse in the evening
  
  
• Chills or shivering
  
  
• Loss of appetite/refusal of feeds
  
  
• Vomiting
  
  
• Extreme weakness
  
  
• Diarrhoea or abdominal pain
  
  

High fever in a child should always be taken seriously.Signs of severe malariaIn severe cases, a child may develop:

• Severe weakness
  
  
• Anaemia (pale look)
  
  
• Convulsions
  
  
• Coma or loss of consciousness
  
  

Severe malaria is a medical emergency and requires urgent hospital care.

Treatment of malaria in children under five

Treatment of malaria in children is similar to that in adults, but doses are adjusted according to the child’s weight [2].

If your child has symptoms suggestive of malaria, it is best to visit a health facility promptly.

Treatment of uncomplicated malaria

For uncomplicated malaria, doctors usually prescribe artemisinin-based combination therapies. The most common combination is artemether–lumefantrine. This is given orally (through the mouth) as syrup, dispersible tablets, or tablets, depending on your child’s age.

If malaria medicines are available over the counter in your country and a hospital is not immediately accessible, you may purchase them. Ensure the correct dose is given for the child’s weight and age. If symptoms do not improve within 24 hours or the child’s condition worsens, seek medical care immediately.

Treatment of complicated (severe) malaria

For severe malaria, artesunate is given intravenously (through the vein) in the hospital. If artesunate is not available, other medicines such as artemether may be used. Treatment may also include supportive care such as blood transfusion.

Prevention of malaria

Malaria can be prevented in your child  through several measures:

• Use of sulfadoxine–pyrimethamine during pregnancy to reduce malaria infection in the mother and placenta, thereby lowering the risk of congenital malaria
  
  
• Sleeping under insecticide-treated nets
  
  
• Indoor residual spraying with insecticides
  
  
• Chemoprevention with sulfadoxine–pyrimethamine for children at high risk (only when prescribed by a doctor)
  
  
• Malaria vaccination starting from five months of age, given in four doses
  
  

2. Pneumonia in Children

Pneumonia is an acute infection of the lungs. It can be caused by microorganisms such as bacteria, viruses, and fungi. Pneumonia leads to the collection of fluid and pus in the air sacs of the lungs, making breathing difficult and reducing the amount of oxygen that reaches the body.

The most common bacterial cause of pneumonia is Streptococcus pneumoniae, while respiratory syncytial virus (RSV) is the most common viral cause, especially in children.

Who Is Affected by Pneumonia?

According to the World Health Organization, pneumonia causes death in up to 14 out of every 100 children under the age of five.Children who are malnourished, living with HIV, or exposed to cigarette smoke at home are at a higher risk of developing pneumonia.

How is Pneumonia Contracted?

Your child can get pneumonia when disease-causing microorganisms enter the lungs. This can happen through: [3]

• Breathing in droplets from the coughs or sneezes of an infected person
  
  
• Close contact with someone who has a respiratory infection
  
  
• Spread of infection from the nose or throat down into the lungs
  
  
• Spread of infection through the bloodstream from another part of the body.
  
  

Children with weak immune systems are more likely to develop pneumonia after exposure.

Symptoms of Pneumonia in a Child

• Fever
  
  
• Fast or difficult breathing
  
  
• Cough
  
  
• Loss of appetite or refusal to feed
  
  

In severe cases, convulsions or coma may occur.

Treatment of Pneumonia

Treatment depends on the cause of pneumonia [3]. Antibiotics are the most common treatment for bacterial pneumonia.. 

• Mild cases are usually treated with oral antibiotics.
  
  
• Severe cases may require hospital admission and intravenous antibiotics, as recommended by your doctor.

Viral pneumonia often resolves on its own, so only supportive treatment is needed

When to See a Doctor

Take your child to the doctor immediately if your child has:

• Fast or difficult breathing
  
  
• High or persistent fever
  
  
• Refusal to feed or drink
  
  
• Extreme weakness, drowsiness, or convulsions

Prevention of Pneumonia in Children

• Good personal and environmental hygiene
  
  
• Avoiding overcrowding
  
  
• Reducing indoor air pollution, including exposure to cigarette smoke
  
  
• Good nutrition to strengthen the immune system
  
  
• Immunisation against infections such as pneumococcal disease, Haemophilus influenzae, and measles

3. Diarrhoeal Disease in Children

Diarrhoea means passing three or more loose or watery stools in a day, or passing stool more frequently than is normal for your child [4]. In children aged 0–59 months, diarrhoea is most commonly caused by an infection in the gut.

Causes of Diarrhoea in Children Under Five

Diarrhoea in your child can be caused by:

• Bacteria, such as Escherichia coli
  
  
• Viruses, such as rotavirus
  
  
• Parasites, such as Entamoeba species
  
  

Your baby can get these microorganisms through contaminated food or water, or through person-to-person contact.The major danger of diarrhoea is loss of water (dehydration) and essential electrolytes that the body needs to function properly. When this happens, some organs may not work well, and if diarrhoea is not treated promptly, it can lead to death.

Who Is Affected by Diarrhoea?

Diarrhoeal disease is the third leading cause of death in children under five years of age. It affects about 1.7 billion children worldwide and causes the death of more than 400,000 children every year.Your child is at higher risk if they are malnourished or live in a developing country.

Symptoms of Diarrhoeal Disease

If your child has diarrhoea, you may notice one or more of the following:

• Passing loose stools more than three times a day
  
  
• Stool that may be blood-stained (dysentery)
  
  

In moderate to severe cases, your child may also have:

• Increased thirst
  
  
• Sunken eyes
  
  
• Extreme weakness or reduced activity (lethargy)
  
  

Treatment of Diarrhoea in Children Under Five

The most important part of treatment is replacing the lost fluids.This is done using:

• Oral Rehydration Salt (ORS) solution is a mixture of water, salt, and sugar. You can buy ORS from a pharmacy or prepare it at home as advised by a health worker.
  
  
• In moderate or severe cases, your child may need intravenous fluids (a drip) at the hospital.
  
  

Other treatments may include:

• Zinc supplements to reduce the severity and duration of diarrhoea
  
  
• Continued and adequate feeding to support recovery and prevent malnutrition
  
  
• Antibiotics if dysentery is suspected
  
  

When to See a Doctor

Diarrhoea can be life-threatening. You should take your child to see a doctor immediately if your child has:

• Signs of dehydration (increased thirst, sunken eyes, extreme weakness)
  
  
• Blood-stained stool
  
  
• Diarrhoea that does not stop or keeps coming back
  
  

Prevention of Diarrhoea in Children Under Five

You can help prevent diarrhoea by:

• Practising exclusive breastfeeding
  
  
• Washing your hands and your child’s hands regularly
  
  
• Using safe and clean drinking water
  
  
• Improving sanitation and the proper disposal of waste
  
  
• Ensuring your child receives the rotavirus vaccine

4. Human Immunodeficiency Virus (HIV) Infection in Children

What is HIV?

HIV, or Human Immunodeficiency Virus, is an infection that attacks your child’s immune system, making it harder for their body to fight infections. In children under 5, HIV is usually passed from mother to child during pregnancy, childbirth, or breastfeeding. Your child is at risk if you are HIV positive or unsure of your status.

How is HIV Diagnosed?

You can know if your child has HIV through specialised tests:

• Polymerase Chain Reaction (PCR) test: This test can detect HIV in your child as early as 6 weeks old by looking for the virus’s RNA and DNA.
  
  
• Antibody tests: For children older than 18 months, tests that detect HIV antibodies can be used.
  
  

Who is affected by HIV?

Globally, about 120,000 children under 5 were newly infected with HIV in 2024, according to UNICEF. The risk is higher in developing countries and is worse in children who are malnourished. HIV can affect your child more severely if they are undernourished, and the risk of death is higher in children under 5 compared to older children or adults [5]. 

What Are the Symptoms of HIV?

If HIV is not treated, it can progress to AIDS, which can make your child develop other illnesses. Symptoms to look out for:

• White patches in the mouth (oral thrush)
  
  
• Swollen lymph nodes in parts of the body
  
  
• Slowed growth or poor weight gain
  
  
• Recurring chest infections
  
  
• Frequent diarrhea
  
  

How is HIV Treated?

If your child is diagnosed with HIV, starting treatment immediately is important. Here’s what you need to know:

• Antiretroviral treatment (ART) reduces the amount of virus in your child’s body.
  
  
• ART is a combination of drugs that your child will need to take daily for life.
  
  
• Your role is crucial: help your child take their medication as prescribed.
  
  
• Attend all follow-up appointments so the doctor can monitor your child’s health.
  
  
• Additional medicines, such as clotrimazole, may be given to prevent lung infections.
  
  

How Can You Prevent HIV in Children?

Preventing HIV in children mainly focuses on stopping mother-to-child transmission, also known as PMTCT (prevention of mother-to-child transmission of HIV). Prevention should begin before pregnancy and continue throughout pregnancy and delivery.You can reduce the risk by:

• Practising safe sexual practices such as abstinence, being faithful to one uninfected partner, and using condoms correctly and consistently to prevent HIV infection before pregnancy.
  
  
• Knowing your HIV status before and during pregnancy by getting tested.
  
  
• Taking antiretroviral medicines during pregnancy and delivery if you are living with HIV. These medicines lower the amount of virus in your blood and reduce the chance of passing HIV to your baby.
  
  
• Registering early for antenatal care and attending your clinic visits regularly, so your healthcare provider can monitor you and guide you appropriately.

5. Tuberculosis in Children

Tuberculosis (TB) is a serious disease caused by bacteria called Mycobacterium, with Mycobacterium tuberculosis being the most common. [6]. The disease occurs when a person breathes in bacteria released by someone with active TB. In children under 5, TB can also be transmitted:

• During pregnancy and delivery, if the mother is infected. This is called congenital tuberculosis, though it is rare.
  
  
• During breastfeeding, though the risk is low if proper care is taken.
  
  

Types of Tuberculosis

• Pulmonary TB – affects the lungs and is the most common form in children [6].
  
  
• Extrapulmonary TB – affects other parts of the body outside the lungs.
  
  

Who is at Risk of Tuberculosis?

• About 1.2 million children are affected by TB each year, with the highest burden in Africa and Asia [7].
  
  
• Children living with HIV are at higher risk due to reduced immunity.
  
  
• Young children are more likely than adults to develop severe TB or TB affecting multiple organs.
  
  

Symptoms of Tuberculosis in Children

TB can sometimes mimic other illnesses and may not show obvious symptoms in its early stages. Common symptoms include:

• Persistent low-grade fever
  
  
• Cough
  
  
• Difficulty breathing
  
  
• Night sweats
  
  
• Weight loss

How is Tuberculosis Diagnosed?If TB is suspected in your child, your doctor may perform tests such as:

• TB skin test
  
  
• TB blood test
  
  
• Chest X-ray
  
  

When to See a Doctor

Take your child to a doctor immediately if they show:

• Persistent cough lasting more than 3 weeks
  
  
• Difficulty breathing or fast breathing
  
  
• Fever that does not improve
  
  
• Unexplained weight loss or poor growth
  
  
• Swelling of the neck, armpits, or other areas (possible signs of extrapulmonary TB)
  
  

Treatment of Tuberculosis

The treatment for TB in children involves a combination of anti-TB medications, just like in adults.

• Medication is given even if the disease is inactive.
  
  
• Doses are adjusted according to your child’s body weight.
  
  
• Following the treatment plan carefully is essential to cure TB and prevent drug resistance.
  
  

Prevention of Tuberculosis

You can help prevent TB in  your child by:

• BCG (Bacillus Calmette-Guérin) vaccination at birth
  
  
• Isoniazid preventive therapy for six months for your child, if you are infected with TB during pregnancy, delivery and breastfeeding period. This should be prescribed by your doctor 
  
  
• Taking your child to the hospital for  TB screening if they are in close contact with TB patients or living with HIV

Conclusion

Deaths among children under five remain a major public health challenge, especially in low-resource settings. Yet, many of these deaths are preventable. Malaria, pneumonia, diarrhoea, HIV, and tuberculosis can be effectively managed when identified early and treated promptly.

Simple actions such as timely hospital visits, complete immunisation, good nutrition, clean water, and proper hygiene can make the difference between life and death.

Refrences

1. Kafai NM, Odom John AR. Malaria in children. Infect Dis Clin North Am [Internet]. 2018 Mar [cited 2026 Jan 17];32(1):189–200. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6051527/
2. WHO guidelines for malaria [Internet]. [cited 2026 Jan 17]. Available from: https://www.who.int/publications/i/item/guidelines-for-malaria
3. Ebeledike C, Ahmad T. Pediatric pneumonia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 [cited 2026 Jan 21]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK536940/
4. Manetu WM, M’masi S, Recha CW. Diarrhea disease among children under 5 years of age: a global systematic review. Open Journal of Epidemiology [Internet]. 2021 June 28 [cited 2026 Jan 20];11(3):207–21. Available from: https://www.scirp.org/journal/paperinformation?paperid=110128
5. Chapman KS, Luhanga M, Mtonga G, Agathis N, Kayira D, Hrapcak S, et al. Mortality among children under five years of age living with hiv on antiretroviral treatment from hiv case surveillance data, Malawi, 2022. Pediatr Infect Dis J [Internet]. 2024 Dec 1 [cited 2026 Jan 20];43(12):1168–70. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11862962/ 
6. Tristram D, Tobin EH. Tuberculosis in children. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 [cited 2026 Jan 20]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK610681/
7. Fronteira I, Pacheco M, Vilichane I, Ricardo E, Aguiar P, Duarte R, et al. Tuberculosis in children under 5 years of age in a low-burden setting: sociodemographic and epidemiological characteristics and healthcare utilization over a 10-year period (2010–2021). Eur J Pediatr [Internet]. 2026 [cited 2026 Jan 20];185(1):49. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12764675

Disclaimer:
The information provided on this website is for general educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

Published January 22, 2026