As at 1st March, 2023, there are 14 confirmed cases in Ghana with 1 death. Lassa fever is an animal-borne, or zoonotic, acute viral illness spread by the common African rat. It is endemic in parts of West Africa including Sierra Leone, Liberia, Guinea and Nigeria. Neighboring countries are also at risk because the animal vector lives throughout the region.
The first documented case occurred in 1969. Lassa fever is named after the town in Nigeria where the first cases occurred.
About 100,000 to 300,000 infections of Lassa fever occur annually, with about 5,000 deaths. Surveillance for Lassa fever varies between locations so these estimates are crude. In some areas of Sierra Leone and Liberia, about 10-16% of people admitted to hospitals annually have Lassa fever. This shows the serious impact the disease has on the region.
Lassa fever is a significant public health concern in Ghana, a West African country that shares borders with Togo, Burkina Faso, and Cote d’Ivoire. The first confirmed case of Lassa fever in Ghana was reported in 2011, and since then, several outbreaks have occurred, with the most recent outbreak occurring in 2020.
Like in other countries in West Africa, the primary mode of transmission of Lassa fever in Ghana is through contact with the urine or feces of infected multimammate rats. These rats are common in Ghana and are often found in homes and other buildings. People can also contract the virus through direct contact with an infected person’s bodily fluids, including blood, urine, saliva, and semen.
The symptoms of Lassa fever in Ghana are similar to those in other countries and can range from mild to severe. They include fever, headache, muscle aches, sore throat, cough, nausea, vomiting, diarrhea, and abdominal pain. In severe cases, the virus can cause hemorrhagic fever, which is characterized by bleeding from the mouth, nose, or other areas of the body. The mortality rate of Lassa fever in Ghana is estimated to be around 10%.
The Ghana Health Service has taken several measures to prevent and control the spread of Lassa fever in the country. These measures include conducting surveillance for suspected cases, providing laboratory testing for diagnosis, and providing treatment and supportive care for patients. The Ghana Health Service has also engaged in public education campaigns to raise awareness about the virus and how to prevent its transmission.
Preventing Lassa fever in Ghana involves taking steps to avoid contact with infected rodents and their bodily fluids. This includes keeping homes and other buildings clean and free of food debris and waste, as well as storing food in rodent-proof containers. People should also avoid handling dead rats or other rodents and should wear protective clothing when cleaning areas where rodents may have been present. In addition, healthcare workers should take precautions when treating patients with suspected or confirmed Lassa fever, including wearing protective clothing and following strict infection control procedures.
Transmission of Lassa Fever
The reservoir, or host, of Lassa virus is a rodent known as the “multimammate rat” (Mastomys natalensis). Once infected, this rodent is able to excrete virus in urine for an extended time period, maybe for the rest of its life. Mastomysrodents breed frequently, produce large numbers of offspring, and are numerous in the savannas and forests of west, central, and east Africa. In addition, Mastomys readily colonize human homes and areas where food is stored. All of these factors contribute to the relatively efficient spread of Lassa virus from infected rodents to humans.
Transmission of Lassa virus to humans occurs most commonly through ingestion or inhalation. Mastomys rodents shed the virus in urine and droppings and direct contact with these materials, through touching soiled objects, eating contaminated food, or exposure to open cuts or sores, can lead to infection.
Because Mastomys rodents often live in and around homes and scavenge on leftover human food items or poorly stored food, direct contact transmission is common. Mastomys rodents are sometimes consumed as a food source and infection may occur when rodents are caught and prepared. Contact with the virus may also occur when a person inhales tiny particles in the air contaminated with infected rodent excretions. This aerosol or airborne transmission may occur during cleaning activities, such as sweeping.
Direct contact with infected rodents is not the only way in which people are infected; person-to-person transmission may occur after exposure to virus in the blood, tissue, secretions, or excretions of a Lassa virus-infected individual. Casual contact (including skin-to-skin contact without exchange of body fluids) does not spread Lassa virus. Person-to-person transmission is common in health care settings (called nosocomial transmission) where proper personal protective equipment (PPE) is not available or not used. Lassa virus may be spread in contaminated medical equipment, such as reused needles.
Signs and Symptoms of Lassa Fever
Signs and symptoms of Lassa fever typically occur 1-3 weeks after the patient comes into contact with the virus. For the majority of Lassa fever virus infections (approximately 80%), symptoms are mild and are undiagnosed. Mild symptoms include slight fever, general malaise and weakness, and headache. In 20% of infected individuals, however, disease may progress to more serious symptoms including hemorrhaging (in gums, eyes, or nose, as examples), respiratory distress, repeated vomiting, facial swelling, pain in the chest, back, and abdomen, and shock. Neurological problems have also been described, including hearing loss, tremors, and encephalitis. Death may occur within two weeks after symptom onset due to multi-organ failure.
The most common complication of Lassa fever is deafness. Various degrees of deafness occur in approximately one-third of infections, and in many cases hearing loss is permanent. As far as is known, severity of the disease does not affect this complication: deafness may develop in mild as well as in severe cases.
Approximately 15%-20% of patients hospitalized for Lassa fever die from the illness. However, only 1% of all Lassa virus infections result in death. The death rates for women in the third trimester of pregnancy are particularly high. Spontaneous abortion is a serious complication of infection with an estimated 95% mortality in fetuses of infected pregnant mothers.
Because the symptoms of Lassa fever are so varied and nonspecific, clinical diagnosis is often difficult. Lassa fever is also associated with occasional epidemics, during which the case-fatality rate can reach 50% in hospitalized patients.
Prevention of Lassa Fever
Primary transmission of the Lassa virus from its host to humans can be prevented by avoiding contact with Mastomys rodents, especially in the geographic regions where outbreaks occur. Putting food away in rodent-proof containers and keeping the home clean help to discourage rodents from entering homes. Using these rodents as a food source is not recommended. Trapping in and around homes can help reduce rodent populations; however, the wide distribution of Mastomys in Africa makes complete control of this rodent reservoir impractical.
When caring for patients with Lassa fever, further transmission of the disease through person-to-person contact or nosocomial routes can be avoided by taking preventive precautions against contact with patient secretions (called VHF isolation precautions or barrier nursing methods). Such precautions include wearing protective clothing, such as masks, gloves, gowns, and goggles; using infection control measures, such as complete equipment sterilization; and isolating infected patients from contact with unprotected persons until the disease has run its course.
Further, educating people in high-risk areas about ways to decrease rodent populations in their homes will aid in the control and prevention of Lassa fever. Other challenges include developing more rapid diagnostic tests and increasing the availability of the only known drug treatment, ribavirin. Research is presently under way to develop a vaccine for Lassa fever
In conclusion, Lassa fever is a significant public health concern in Ghana, and the Ghana Health Service is taking measures to prevent and control its spread. Prevention measures, including rodent control and infection control procedures in healthcare settings, are crucial for reducing the spread of Lassa fever in Ghana. Early diagnosis and treatment are also essential for improving the chances of survival for patients with the illness.
Source: CDC
