Simian Mandrill Malaria
Simian malaria is a parasitic blood disease that affects non-human primates, including mandrills. It is caused by parasites of the Plasmodium genus, close to those responsible for human malaria but generally specific to monkeys. The disease...
What is it?
Simian malaria is a parasitic blood disease that affects non-human primates, including mandrills. It is caused by parasites of the Plasmodium genus, close to those responsible for human malaria but generally specific to monkeys. The disease is transmitted by mosquito bite and causes destruction of red blood cells, leading to fever and anemia. Although documented mainly in species of African primates living in the wild or in captivity in mosquito areas, it remains a condition to monitor in mandrills in zoos or sanctuaries.
Key point
Severe forms with significant anemia can be life-threatening, particularly in young mandrills or already weakened animals.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Clinical signs are often subtle at first, making the disease difficult to spot without a blood test. A variable fever, general depression and decreased appetite are typically observed. In the event of a more marked infection, the animal may present pallor of the mucous membranes linked to anemia, weakness and progressive weight loss. Some infected animals remain carriers without visible signs for long periods.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
Simian malaria is caused by microscopic parasites of the genus Plasmodium, specific to non-human primates. These parasites invade and destroy the red blood cells of the infected animal. In the mandrill, as in other African primates, several species of Plasmodium specific to monkeys may be involved. The parasite is transmitted by the bite of mosquitoes, mainly of the Anopheles genus, which act as vectors by injecting the infectious form during the blood meal.
Mandrills living in geographic areas where Anopheles mosquitoes are abundant, particularly in the rainy season, are most at risk. Young animals, weakened, stressed or immunocompromised individuals present an increased risk of severe disease. Proximity to stagnant water points around enclosures or in the natural habitat also favors the presence of mosquito vectors.
Transmission
Transmission occurs exclusively through the bite of a vector mosquito of the Anopheles genus having previously bitten an infected animal. There is no direct transmission from one mandrill to another by simple contact; the mosquito is an obligatory link in the cycle. Accidental contamination by direct exposure to infected blood remains theoretically possible but is exceptional.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian specializing in primates first relies on the clinical history of the animal and the signs observed (fever, depression, pallor). The definitive diagnosis is based on an examination of blood under a microscope, which makes it possible to identify the parasite responsible in the red blood cells. Additional analyzes (blood count, search for anemia, general assessment) help to assess the severity and guide treatment. In some centers, more in-depth molecular testing can confirm the exact species of parasite involved.
Treatment
The treatment is based on antimalarial molecules belonging to families used in primate medicine, chosen and adapted by the veterinarian according to the suspected Plasmodium species and the condition of the animal. Supportive treatment (rehydration, management of anemia) may be associated in more severe forms. No protocol should be applied without veterinary supervision, the choice and duration of treatment depending on a precise clinical assessment.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Prevention is essentially based on the fight against mosquito vectors: mosquito nets on enclosures, elimination of stagnant water conducive to insect reproduction, and use of repellents adapted to the animals' living areas. In zoological parks, regular health monitoring and structured vector control around enclosures significantly reduce the risk of exposure. There is no vaccine available for this disease in mandrills.
Vaccination
No vaccine is currently available to prevent simian malaria in mandrills.
Possible complications
An untreated severe infection can cause profound anemia through massive destruction of red blood cells. In weakened, young or immunocompromised animals, the attack can be complicated by coagulation disorders, damage to internal organs (spleen, liver) and, in severe forms, a state of shock which can be life-threatening. Relapses are possible with certain species of Plasmodium which persist in dormant form in the liver.
When to see a veterinarian
Persistent or recurrent fever in mandrills
Marked depression or refusal to eat
Visible pallor of the mucous membranes (gums, lips)
Weakness or gradual weight loss with no other obvious cause
Any unusual behavior after exposure to mosquitoes in a risk area
Prognosis
The prognosis is most often favorable when the disease is detected early and treated quickly, particularly in an adult animal in good general condition. Severe forms with marked anemia or multi-organ complications darken the prognosis, especially in young people or otherwise weakened animals. Follow-up after treatment is useful to monitor possible relapses.
Frequently asked questions
Can monkey mandrill malaria be transmitted to humans?
Plasmodium species that naturally infect African monkeys are generally specific to non-human primates. The risk of transmission to humans is considered very low, but it is not completely excluded for certain species of Plasmodium simiens documented elsewhere in the world. As a precaution, any contact with blood from an infected animal should be avoided.
How can a mandrill in captivity get malaria?
The animal must be bitten by a mosquito of the Anopheles genus carrying the parasite. The risk exists especially in parks and sanctuaries located in areas where these mosquitoes are present and active, particularly in the hot and humid season.
Is monkey malaria still serious in mandrills?
No. Many infections remain subtle or moderate, especially in a healthy adult animal. The severity depends on the species of Plasmodium involved, the parasite load and the general condition of the animal, including its age and immune status.
Can a cured mandrill get sick again?
Yes, some forms of Plasmodium can persist dormantly in the liver and cause a relapse months after apparent recovery. Regular veterinary monitoring is recommended after an episode of monkey malaria.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
CDC — Centers for Disease Control and Prevention
Content reviewed by the TunisieVet editorial team · Updated 22 September 2026
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